Building Models in ADAMS

Building Models in ADAMS/View

About This Guide 3

About Parts 5

Creating Parts 17

Modifying Parts 79

About Constraining Your Model 125

Working with Joints 139

Applying Motion 177

Applying Forces to Your Model 195

Working with Contacts 271

Storing and Accessing Data 315

Using System Elements to Add Equations 365

Editing Modeling Objects 391

Positioning and Rotating Objects 439

2 Building Models in ADAMS/View Copyright

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Part number: 110VIEWBM-01


About This Guide3

About This Guide

Welcome to ADAMS/View

ADAMS/View is a powerful modeling and simulating environment that lets you build, simulate, and refine models of mechanical systems.

This guide explains how build models in ADAMS/View. It assumes you know the basics of using ADAMS/View. For an introduction to ADAMS/View, see the guide, Getting Started Using ADAMS/View.


About This Guide4

1 About Parts

OverviewParts define the objects in your model that can have mass and inertia properties and can move. All forces and constraints that you define in your model act on these parts during a simulation. This chapter explains how to create and modify parts. It contains the following sections:

■ Overview of ADAMS/View Parts, 6

■ Before You Begin Creating Parts, 9

■ About Rigid Bodies, 10


About Parts6

Overview of ADAMS/View PartsADAMS/View provides a complete library of parts that you can create. The following sections explains more about ADAMS/View parts.

■ Types of Parts, 6

■ About the Ground Part, 7

■ Local Coordinate Systems, 7

■ Degrees of Freedom for Parts, 8

■ Part Naming Conventions, 8

Types of Parts

ADAMS/View provides you with three different types of parts that you can create:

■ Rigid Bodies - Parts in your model that have mass and inertia properties. They cannot deform.

■ Flexible Bodies - Parts that have mass and inertia properties and can bend when forces are applied to them. Basic ADAMS/View provides you with the ability to create discrete flexible links. For more functionality, you can purchase ADAMS/Flex. For information on purchasing ADAMS/Flex, see your MDI sales representative, and for information on using ADAMS/Flex, refer to the guide, Using ADAMS/Flex.

■ Point Masses - Parts that have only mass. They have no extent and, therefore, no inertia properties.

In addition, ADAMS/View provides a ground part that is already created for you.


About Parts7

About the Ground Part

The ground part is the only part in your model that must remain stationary at all times. ADAMS/View creates the ground part automatically when you create a model. The ground part does not have mass properties or initial velocities and does not add degrees of freedom into your model. (For more on degrees of freedom, see Constraints and Degrees of Freedom on page 128.)

The ground part acts as the global coordinate system that defines the global origin (0,0,0) and axes about which you create your model. You cannot specify its position. You can add geometry to the ground part.

In addition, by default, the ground part also acts as the inertial reference frame with respect to which all of the part velocities and accelerations are calculated. You can also select another part as the inertial reference frame. You can select another part through the Command Navigator.

Note that although the ground part is the only part in your model that must remain stationary at all times, you can move the geometry and constraints attached to the ground part. Since geometry and constraints are tied to markers, you can use the Select List Manager to select all the markers on ground and then translate and rotate the ground entities with the rest of your model. For information on selecting objects, see Selecting and Deselecting Objects on page 392, and for information on moving objects, see Positioning and Rotating Objects on page 439.

Local Coordinate Systems

As you create parts, ADAMS/View assigns a coordinate system to each part, known as its local coordinate system. A part’s local coordinate system moves with the part and its original position defaults to that of the global coordinate system.

The local coordinate system is a convenient way to define the position and location of objects. ADAMS/View also returns simulation results, such as the position of a part, as the displacement of a part’s local coordinate system with respect to the global coordinate system. It returns object results, however, as the displacement of a part’s center of mass relative to the global coordinate system.


About Parts8

Degrees of Freedom for Parts

Each rigid body that you create can move within all degrees of freedom; a point mass can move within three translational degrees of freedom. You can constrain the movement of parts by:

■ Adding them to the ground part, which means they are fixed to the ground and cannot move in any direction. Each time you create geometry, ADAMS/View gives you the option to add it to ground, create a new part, or add it to an existing part.

■ Adding constraints, such as joints, to define how the parts are attached and how they move relative to each other. For more on adding constraints and limiting the movement of parts, see Working with Joints on page 139.

Part Naming Conventions

As you create parts, ADAMS/View automatically generates names for them based on their type and the number of objects of that type in your model. For example, when you create a point mass, ADAMS/View names it POINT_MASS_1. For all rigid bodies, except points and coordinate system markers, ADAMS/View uses the name PART regardless of the type of geometry. For example, if you create a box, ADAMS/View names it PART_1. When you create a second box, ADAMS/View names it PART_2, and so on. You can rename your parts. For more information, see Renaming Objects on page 425.


About Parts9

Before You Begin Creating PartsBefore you begin creating the parts of your model, you might want to take some time to set up your modeling environment and learn some drawing and placement techniques. To help you place parts accurately, do the following, which are outlined in the guide, Learning ADAMS/View Basics:

■ Turn on the working grid so that the points snap to a grid. In addition, ADAMS/View draws objects parallel to the current working grid so by displaying it you can better see how your objects are being drawn. For information on displaying the working grid, see Setting Up the Working Grid on page 127.

■ Display the coordinate window so that you can view the coordinate values as you place points. For more information, see Working with the Coordinate Window on page 124.

■ Be sure to set the current units to those required for your model. See Specifying the Type of Coordinate System on page 30.

■ Review the different tools for drawing and placing objects in Techniques for Creating and Placing Objects on page 191.


About Parts10

About Rigid BodiesThe most common type of part in your model is a rigid body. Rigid bodies are parts that cannot deform. They are physical objects in which the distance between any two points within the body remains constant. The rigid body can move relative to other parts and can be used as a reference frame to measure another part’ s velocity or acceleration. ADAMS/View provides a library of geometry that you can use to create rigid bodies.

In ADAMS/View, you create rigid bodies by drawing the geometric objects that represent them. A part can be made up of many different geometric objects. ADAMS/View calculates the mass and inertia of the rigid body based on its solid geometry and its material type, which is steel by default. You can modify the default properties for the part and change how ADAMS/View calculates the mass and inertia of a solid rigid body. For more information, see Modifying Parts on page 79.

The next sections explain more about creating rigid bodies:

■ Ways to Create Rigid Bodies, 11

■ Building Parameterization into Your Model as You Create Parts, 11

■ Types of Rigid Body Geometry, 13

■ Accessing the Geometric Modeling Tools, 14


About Parts11

Ways to Create Rigid Bodies

Each time you create geometry, you can select to do one of the following:

■ Create a new part containing the geometry.

■ Add the geometry to an existing part.

■ Add the geometry to ground. You add geometry to ground if the geometry does not move or influence the simulation of your model. For example, if you are simulating a car driving around a race track, the geometry that defines the race track can be added to ground. (You can also fix parts temporarily to ground using a fixed joint. For more information, see Working with Simple Idealized Joints on page 141.)

In addition, you specify the location of the geometry in space. You can select to define the location of the geometry:

■ Graphically, by picking locations on the screen or by selecting an object on the screen that is at the desired location.

■ Precisely, by entering coordinate locations.

For more tips on techniques for placing objects, see Techniques for Creating and Placing Objects on page 191 of the guide, Learning ADAMS/View Basics.

Building Parameterization into Your Model as You Create Parts

As you create rigid bodies in your model, you can define them so that the location or orientation of one object affects the location or orientation of another body. This is called parameterizing your model.

Parameterizing your model simplifies changes to your model because it helps you automatically size, relocate, and orient objects. For example, if you parameterize the geometry of two links to the location of a point, when you move the point, the link geometry changes accordingly, as shown in Figure 1.


About Parts12

Figure 1. Example of Parameterizing Locations

The ways in which you can build parameterization into your model while creating rigid bodies include the following:

■ Attach objects to points so that when you change the location of the points, the body locations and orientations update accordingly.

As you create a point, ADAMS/View gives you the option to attach other nearby objects to the point. The sections in this chapter that explain how to create points also explain how to attach objects to them.

■ Define design variables to represent values of your rigid body geometry, such as the length or width of a link. You can create design variables for any values you specify for a rigid body. Design variables are needed when you run tests on your model, such as design studies. For more information on design variables, see Using Design Variables on page 27 of the guide, Refining Model Designs in ADAMS/View.

■ Create expressions that calculate the values of your rigid bodies, such as the length or width of a box. You can specify expressions for any values you specify for a rigid body geometry. For more information on creating expressions, see the guide, Using the ADAMS/View Function Builder.

You can also parameterize your model after you build it. For more information on parameterization, see Automating Design Changes Using Parameterization on page 13 of the guide, Refining Model Designs in ADAMS/View.

Dragging POINT_1 upward ... Reshapes the links, accordingly

POINT_1

POINT_1


About Parts13

Types of Rigid Body Geometry

There are two types of geometry that you can use to create rigid bodies.

■ Construction geometry - These are primitive objects that have no mass. They include points and markers as well as wire geometry, such as lines, arcs, and splines. You can use construction geometry to define other geometry. For example, you use points to define locations about which you orient other objects.

■ Solid geometry - ADAMS/View comes with a set of predefined solid geometry, including boxes, cylinders, and links. You can also create solid geometry from construction geometry by extruding it.


About Parts14

Accessing the Geometric Modeling ToolsYou can create rigid body geometry using the tools on the Geometric Modeling palette or the Geometric Modeling tool stack on the Main toolbox. The palette and tool stack contain the same tools so you can choose whichever one you are most comfortable using. The Geometric Modeling palette and tool stack are shown below. For more on tool stacks and palettes, see the section, Using Toolboxes and Toolbars on page 47 of the guide, Learning ADAMS/View Basics.

Figure 2. Geometric Modeling Palette and Tool Stack

Geometric Modeling palette Geometric Modeling toolstack on Main toolbox

Settingscontainer


About Parts15

As you create geometry, ADAMS/View provides settings that you can control when drawing the geometry. It provides the settings in a container at the bottom of the palette or Main toolbox. The settings change depending on the type of geometry that you are creating. For example, Figure 2 shows the length, width, and depth values associated with creating link geometry.

You can use the settings to control how you want ADAMS/View to draw the geometry. For example, when you create a link, ADAMS/View lets you specify its width, length, and height before drawing. Then, as you create the link, these dimensions are set regardless of how you move the mouse. You can also define design variables or expressions for these setting values.

To display the Geometric Modeling palette:

■ From the Build menu, select Bodies/Geometry.

To display the contents of the Geometric Modeling tool stack:

■ From the Main toolbox, right-click the Geometric Modeling tool stack. By

default, the Link tool appears at the top of the tool stack.


About Parts16

2 Creating Parts

OverviewIn this chapter, you’ ll learn how to create the different types of parts. It contains the sections:

■ Creating Construction Geometry, 18

■ Creating Solid Geometry, 31

■ Creating Complex Geometry, 49

■ Merging Geometry, 62

■ Working with Flexible Links, 63

■ Working with Point Masses, 73

■ Creating a Spline from a Trace, 75

Building Models Using ADAMS/View

Creating Parts18

Creating Construction GeometryYou can create several types of construction geometry. You draw construction geometry normal to the screen or the working grid, if you turned it on.

The next sections explain how to create construction geometry.

■ Defining Points, 18

■ Defining Coordinate System Markers, 21

■ Creating Lines and Polylines, 23

■ Creating Arcs and Circles, 25

■ Creating Splines, 28

Defining Points

Points define locations in three-dimensional space upon which you can build your model. They allow you to build parameterization between objects, as well as position objects. For example, you can attach a link to points so that each time you move the points, the link’s geometry changes accordingly (For an example, see Figure 1). You can also use points to define the location where modeling objects connect, such as the point where a joint connects two parts. Points do not define an orientation, only a location.

As you create a point, you define whether ADAMS/View should add it to ground or to another part. In addition, you specify whether other parts near the same location should be attached (parameterized) to the point. If you attach other bodies to the point, then the location of those bodies is tied to the location of that point. As you change the location of the point, the location of all attached bodies change accordingly.

Note: You should not attach a part’ s center of mass marker to a point, however. If you attach a center of mass marker, ADAMS/View removes the parameterization whenever it recomputes the center of a part, unless you defined mass properties for the part.


Creating Parts19

For more information on attaching points, see Building Parameterization into Your Model as You Create Parts on page 11. For more information on parameterizing your model, see the guide, Refining Model Designs in ADAMS/View.

ADAMS/View assigns the point a default name. The default name is POINT followed by a number representing the point (for example, POINT_1, POINT_2, and so on.).

After creating the point, you can modify its name and set its location using the Table Editor. For more information on editing objects using the Table Editor, see Editing Objects Using the Table Editor on page 401.

To quickly access the Table Editor:

1 From the Geometric Modeling tool stack, select the Point tool .

2 From the settings container, select Point Table.


Creating Parts20

To create a point:

1 From the Geometric Modeling tool stack or palette, select the Point tool .

2 In the settings container, specify the following:

■ Whether you want the point added to ground or to another part in your model.

■ Whether you want to attach nearby objects to the point. For information on attaching objects, see Building Parameterization into Your Model as You Create Parts on page 11.

3 If you selected to add the point to another part in your model, select the part.

4 Place the cursor where you want the point to be located and click the mouse button.

Tips: If you want to place the point at the location of another object, right-click near the object. ADAMS/View displays a list of objects near the cursor. Select the object at whose location you want to place the point. ADAMS/View creates the point at that location.

If you want to specify precise coordinates, right-click away from the object. A dialog box for entering the location of the point appears. For information on using the dialog box, see Entering Precise Location Coordinates on page 194 of the guide, Learning ADAMS/View Basics.


Creating Parts21

Defining Coordinate System Markers

You can create a marker defining a local coordinate system on any part in your model or ground. The marker has a location (the origin of the coordinate system) and an orientation. ADAMS/View automatically creates markers at the center of mass of all solid geometry and at anchor points on geometry that define the location of the object in space. For example, a link has three markers: two at its endpoints and one at its center of mass. ADAMS/View also creates markers automatically for you when you constrain objects, such as add a joint between parts.

ADAMS/View displays markers as triads. Figure 3 shows how markers appear for boxes and links.

Figure 3. Marker Screen Icons

You create markers by specifying their location and orientation. You can align the orientation of the marker with the global coordinate system, the current view coordinate system, or a coordinate system that you define. When you define a coordinate system, you specify one or two of its axes and ADAMS/View calculates the other axes accordingly.

ADAMS/View assigns the marker a default name. The default name is MARKER followed by a number representing the marker (for example, MARKER_1, MARKER_2, and so on).

Note: You can parameterize the locations and orientations of other objects to that of markers. For example, you can align the location of a part to be the same as a marker regardless of how the marker moves. Unlike points, whose parameterization is automatic, you must set up relationship of markers to other objects. For more information on establishing parameteric relationships, see the guide, Refining Model Designs in ADAMS/View.

y

zx

y

zx

y

z xy

z x

Marker Icony

zx


Creating Parts22

To create a marker:

1 From the Geometric Modeling tool stack or palette, select the Marker tool .


■ Whether you want the marker added to ground or to another part in your model.

■ How you want to orient the marker. From the Orientation option menu, select an orientation method.

3 If you selected to add the marker to a part, select the part to which you want to add the marker.

4 Place the cursor where you want the marker to be located and click.

5 If you selected to orient the marker to anything other than the global or view coordinate system, select the directions along which you want to align the marker’s axes. Do this for each axis that you selected to specify.

ADAMS/View draws the marker aligning its axes as specified.


Creating Parts23

Creating Lines and Polylines

You can create both single- and multi-line segments (polylines). In addition, you can create open or closed polylines (polygons). Figure 4 shows examples of lines, polylines, and closed polylines that you can create in ADAMS/View.

Figure 4. Examples of Lines and Polylines

Before drawing lines or polylines, you can specify the length of the line or lines to be created so you can quickly create perfectly sized lines and polylines. When creating a single line, you can also specify the angle of the line. The angle you specify is relative to the x-axis of the global coordinate system or the working grid, if it is turned on.

When you create line geometry, you can select to create a new part consisting of the line geometry or add the line geometry to an existing part. If you create a new part, it has no mass since it is composed of only wire geometry. You can extrude the lines into solid geometry that has mass. For more information, see Creating Complex Geometry on page 49.

ADAMS/View places hotpoints at the endpoint of each line segment after you draw the objects. The hotpoints let you reshape the lines. If you create a closed polyline, ADAMS/View maintains it as a closed polyline regardless of how you move the hotpoints. For more information on modifying geometry using hotpoints, see Using Hotpoints to Graphically Modify Geometry on page 80.

You can also use the line or polyline modify dialog box to more accurately place the points that make up the line or polyline. You can also read in location points from a file. For more information, see Using Dialog Boxes to Precisely Modify Geometry on page 81, and Editing Locations Using the Location Table on page 102.

Line Open polyline Closed polyline(polygon)


Creating Parts24

To draw a single line:

1 From the Geometric Modeling tool stack or palette, select the Polyline tool .

2 In the settings container, do the following:

■ Specify whether you want to create a new part composed of the geometry or add the geometry to an existing part or ground.

■ Set the type of line to be drawn to One Line.

■ If desired, set the length and angle of the line.

3 Position the cursor where you want the line to begin and click.

4 Move the cursor in the direction you want to draw the line.

5 When the line is the desired length and orientation, click again to end the line.

To draw an open or closed polyline:

1 From the Geometric Modeling tool stack or palette, select the Polyline tool .



■ Set the type of line to be drawn to Polyline.

■ If desired, set the length of the line segments.

■ Select whether you want a closed polyline (polygon) by selecting Closed.

3 Position the cursor where you want the polyline to begin and click.

4 To create the first line segment, drag the cursor and click to select its endpoint.

5 To add line segments to the polyline, continue dragging the cursor and clicking.


Creating Parts25

6 To stop drawing and create the open or closed polyline, right-click. If you selected to create a closed polyline, ADAMS/View automatically draws a line segment between the last and first points to close the polyline. Note that clicking the right mouse button does not create another point.

Tip: While creating the polyline, you can remove the last line segment that you created by clicking its endpoint. You can continue removing line segments in the reverse order that you created them.

Creating Arcs and Circles

You can create arcs and circles centered about a location. You begin drawing an arc by specifying its starting and ending angles. You then indicate its center location and set its radius and the orientation of its x axis. You can also specify the arc’s radius before you draw it. ADAMS/View draws the angle starting from the x-axis that you specify and moving counterclockwise (right-hand rule).

Figure 5 shows the elements of an arc that you specify as you create the arc. This example shows a 60-degree angle with a starting angle of 15 degrees and an ending angle of 75 degrees.

Figure 5. Elements of an Arc

Center location

180°

90°

0°

75°

360°

15°

60°

Starting angle

Endingangle

Radius


Creating Parts26

Before you create arc geometry, you can select to create a new part consisting of the arc geometry or add the arc geometry to an existing part or ground. If you create a new part, it has no mass since it is composed of only wire geometry. You can extrude a circle into solid geometry that has mass. For more information, see Creating Complex Geometry on page 49.

To draw an arc:

1 From the Geometric Modeling tool stack or palette, select the Arc tool .


■ Specify whether you want to create a new part composed of the geometry or add the geometry to an existing part or ground. By default, ADAMS/View creates a new part.

■ If desired, set the radius of the arc.

■ Specify the starting and ending angles of the arc. The default is to create a 90-degree arc from a starting angle of 0 degrees.

3 Click where you want the center of the arc and then drag the mouse to define the radius of the arc and the orientation of the x-axis. ADAMS/View displays a line on the screen to indicate the x-axis. If you specified the radius of the arc in the settings container, ADAMS/View maintains that radius regardless of how you drag the mouse.

4 When the radius is the desired size, click.


Creating Parts27

To draw a circle:

1 From the Geometric Modeling tool stack or palette, select the Arc tool .


■ Specify whether you want to create a new part or add the geometry to an existing part. By default, ADAMS/View creates a new part.

■ If desired, set the radius of the circle.

■ Select Circle.

3 Click where you want the center of the circle and then drag the mouse to define the radius of the circle. If you specified the radius of the circle in the settings container, ADAMS/View maintains that radius regardless of how you drag the mouse.

4 When the radius is the desired size, click.


Creating Parts28

Creating Splines

A spline is a smooth curve that a set of location coordinates define. You create splines by defining the locations of the coordinates that define the curve or by selecting an existing geometric curve and specifying the number of points to be used to define the spline. ADAMS/View produces a smooth curve through the points. You can also close the spline or leave it open. A closed spline must be composed of at least eight points; an open spline must be composed of at least four points. Examples of closed and open splines are shown in Figure 6.

Figure 6. Examples of Splines

When you create spline geometry, you can select to create a new part consisting of the spline geometry or add the spline geometry to an existing part or ground. If you create a new part, it has no mass since it is composed of only wire geometry. You can extrude a closed spline into solid geometry that has mass. For more information, see Creating Complex Geometry on page 49.

ADAMS/View places hotpoints at locations on the spline as you draw it. The hotpoints let you reshape the splines. For more information on modifying geometry using hotpoints, see Modifying Rigid Body Geometry on page 80.

You can also modify the spline by editing the point locations directly or by changing the curve and matrix data elements that ADAMS/View creates to support the spline. In addition, you can change the number of segments that ADAMS/View creates through the spline. For more information on modifying splines, see Using Dialog Boxes to Precisely Modify Geometry on page 81.

Note: You can also create a spline in the following ways:

■ Creating a Spline from a Trace, 75

■ Creating Data Element Splines, 332

Closed spline Open spline

y

z x

y

z x


Creating Parts29

To create a spline by selecting points on the screen:

1 From the Geometric Modeling tool stack or palette, select the Spline tool .



■ Select whether you want the spline to be closed or open.

3 Place the cursor where you want to begin drawing the spline and click.

4 Click the locations where you want the spline to pass through. You must specify at least eight locations for a closed spline and four locations for an open spline.

Tip: If you make a mistake, click the last location you defined. You can continue removing locations by clicking on each location in the reverse order that you defined them.

5 To stop drawing the spline, right-click.


Creating Parts30

To create a spline by selecting an existing curve:

1 From the Geometric Modeling tool stack or palette, select the Spline tool .



■ Select whether you want the spline to be closed or open.

■ Select to create a spline by selecting a curve.

■ In the # Points text box, set how many points you want used to define the curve or clear the selection of Spread Points and let ADAMS/View calculate the number of points needed.

3 Select the curve.


Creating Parts31

Creating Solid GeometrySolid geometries are three-dimensional objects. You can create solid geometry from ADAMS/View library of solids or extrude closed wire geometry into a solid. In addition, you can combine solid geometry into more complex geometry or modify the geometry by adding features, such as fillets or chamfers.

The following sections explain how to create solids from ADAMS/View library of solids. For information on creating more complex geometry, see Creating Complex Geometry on page 49.

■ Creating a Box, 32

■ Creating Two-Dimensional Plane, 34

■ Creating a Cylinder, 35

■ Creating a Sphere, 36

■ Creating a Frustum, 37

■ Creating a Torus, 38

■ Creating a Link, 40

■ Creating a Plate, 41

■ Creating an Extrusion, 43

■ Creating a Revolution, 47


Creating Parts32

Creating a Box

A box is a three-dimensional solid block. You draw the box’s length and width in the plane of the screen or the working grid, if it is turned on. ADAMS/View creates a solid box with a depth that is twice that of the shortest dimension of the box (d = 2 * min(l,h)). You can also specify the length, height, or depth of the box before you draw it.

The box dimensions are in screen coordinates with the height up, length to the left, and depth out of the screen or grid. Figure 7 below shows the dimensions of a box.

Figure 7. Example of a Box

One hotpoint appears after you draw the box. It lets you modify the length, height, and depth of the box. For more information on modifying geometry using hotpoints, see Using Hotpoints to Graphically Modify Geometry on page 80.

LengthDepth

Height


Creating Parts33

To create a box:

1 From the Geometric Modeling tool stack or palette, select the Box tool .



■ If desired, set any of length, height, or depth dimensions of the box.

3 Place the cursor where you want a corner of the box and click and hold down the left mouse button.

4 Drag the mouse to define the size of the box. If you specified any of the length, height, or depth dimensions of the box in the settings container, ADAMS/View maintains those dimensions regardless of how you drag the mouse.

5 Release the mouse button when the box is the desired size.


Creating Parts34

Creating Two-Dimensional Plane

A plane is a two-dimensional box. You can draw a plane’ s length and width in the plane of the screen or the working grid, if it is turned on. You will find planes most useful when you are creating contact forces between objects, as explained in Working with Contact Forces on page 290.

Figure 8. Example of a Plane

When you create a plane, you can select to create a new part consisting of the plane geometry or add the plane geometry to an existing part or ground. If you create a new part, it has no mass since it is composed of only wire geometry.

One hotpoint appears after you draw the plane. It lets you modify the length and height of the plane. For more information on modifying geometry using hotpoints, see Using Hotpoints to Graphically Modify Geometry on page 80.

To create a plane:

1 From the Geometric Modeling tool stack or palette, select the Plane tool .

2 In the settings container, specify whether you want to create a new part composed of the geometry or add the geometry to an existing part or ground.

3 Place the cursor where you want a corner of the box and click and hold down the left mouse button.

4 Drag the mouse to define the size of the box.

5 Release the mouse button when the box is the desired size.


Creating Parts35

Creating a Cylinder

A cylinder is a solid with a circular base. You draw the cylinder’s center line and ADAMS/View creates the cylinder with a radius 25% of the length of the center line. Before you draw a cylinder, you can also specify its length and radius. ADAMS/View draws the center line of the cylinder in the plane of the screen or the working grid, if you have it turned on.

Figure 9. Example of a Cylinder

Two hotpoints appear after you draw a cylinder. One lets you modify the length of the cylinder and one lets you set its radius. For more information on modifying geometry using hotpoints, see Using Hotpoints to Graphically Modify Geometry on page 80.

To create a cylinder:

1 From the Geometric Modeling tool stack or palette, select the Cylinder tool .



■ If desired, set the length or radius dimensions of the cylinder in the settings container.

3 Click where you want to begin drawing the cylinder.

4 Drag the mouse to size the cylinder. If you specified any of the length and radius dimensions of the cylinder in the settings container, ADAMS/View maintains those dimensions regardless of how you drag the mouse.

5 When the cylinder is the desired size, click.

Length

Radius

Centerpoint


Creating Parts36

Creating a Sphere

A sphere is a solid ellipsoid whose three radii are of equal length. You draw the sphere by indicating its center point and the radius for the three radii. Before you draw the sphere, you can also specify the radius value for the three radii. The following figure shows an example of a sphere and its three radii.

Figure 10. Example of a Sphere

After you draw the sphere, three hotpoints appear on it that let you reshape the radii of the sphere. For example, you can elongate the sphere into an ellipsoidal shape. For more information on modifying geometry using hotpoints, see Using Dialog Boxes to Precisely Modify Geometry on page 81.

To create a sphere:

1 From the Geometric Modeling tool stack or palette, select the Sphere tool .



■ If desired, set the radius of the sphere.

3 Click where you want the center of the sphere.

4 Drag the mouse to size the sphere. If you specified a radius dimension for the sphere in the settings container, ADAMS/View maintains that dimension regardless of how you drag the mouse.

5 When the sphere is the desired size, click.

RadiiCenterpoint


Creating Parts37

Creating a Frustum

A frustum is a cone, the top of which has been cut off. You create a frustum by drawing its length. ADAMS/View makes the bottom radius 12.5% of the length and makes the top radius of the frustum 50% of the radius of the base radius. Before drawing, you can also specify its length and the radii of its bottom and top.

Figure 11. Example of a Frustum

Three hotpoints appear on a frustrum after you draw it. One controls the length of the frustum, one controls its top radius, and the other controls the bottom radius. For more information on modifying geometry using hotpoints, see Using Hotpoints to Graphically Modify Geometry on page 80.

To create a frustum:

1 From the Geometric Modeling tool stack or palette, select the Frustum tool .



■ If desired, set the length or radii of the frustum.

3 Click where you want to begin drawing the frustum.

4 Drag the mouse to size the frustum. If you specified the length or radii of the frustum in the settings container, ADAMS/View maintains those dimensions regardless of how you drag the mouse.

5 When the frustum is the desired size, click.

Top

Bottom

Radius

Radius

Length


Creating Parts38

Creating a Torus

A torus is a solid circular ring. You draw the ring from the center outward. By default, ADAMS/View makes the radius of outer ring (minor radius) 25% of the inner ring (major radius). You can also specify the minor and major radii before you draw.

Figure 12. Example of a Torus

Two hotpoints appear on a torus after you draw it. One controls the centerline of the torus’ circular shape and the other controls the radius of the circular cross section. For more information on modifying geometry using hotpoints, see Using Hotpoints to Graphically Modify Geometry on page 80.

Minor radius

Center point

Major radius


Creating Parts39

To create a torus:

1 From the Geometric Modeling tool stack or palette, select the Torus tool .



■ If desired, set the inner and outer radii of the torus.

3 Place the cursor where you want the center of the torus and click.

4 Drag the mouse to define the radius of the torus. If you specified the radii of the torus in the settings container, ADAMS/View maintains those dimensions regardless of how you drag the mouse.

5 When the torus is the desired size, click.


Creating Parts40

Creating a Link

You create a link by drawing a line indicating the link’s length. By default, ADAMS/View creates the link with a width that is 10% of the indicated length and a depth that is 5% of the length. The radius of the ends of the link is equal to half the width. Before drawing, you can also define the length, width, and depth of the link.

Figure 13. Example of a Link

Two hotpoints appear after you draw the link: one hotpoint lets you modify the length of the link and the other hotpoint lets you modify the depth, width, and height. For more information on modifying geometry using hotpoints, see Using Hotpoints to Graphically Modify Geometry on page 80.

To create a link:

1 From the Geometric Modeling tool stack or palette, select the Link tool .



■ If desired, set any of the length, width, or depth dimensions of the link.

3 Place the cursor where you want to begin drawing the link and click.

4 Drag the mouse until the link is the desired size and then release the mouse button. If you specified the length, width, and depth of the link in the settings container, ADAMS/View maintains those dimensions regardless of how you drag the mouse.

Length

Width

DepthXX


Creating Parts41

Creating a Plate

A plate is an extruded polygon solid with rounded corners. You create a plate by indicating the location of its corners. You must select at least three locations. The first location you select acts as an anchor point defining the position and orientation of the plate in space. ADAMS/View creates coordinate system markers at each location. The marker at the anchor point is called the reference marker.

After you indicate the locations, ADAMS/View creates a polygon with the specified number of sides and extrudes it. By default, ADAMS/View creates the plate with a depth that is 1 and has corners with radii of 1 in current length units. Before drawing, you can also specify the thickness and radius of the corners of the plate.

Figure 14. Example of a Plate

After you draw a plate, a hotpoint appears at the reference marker. It lets you change the depth of the plate. For more information on modifying geometry using hotpoints, see Using Hotpoints to Graphically Modify Geometry on page 80.

You can also use the Geometry Modify Plate dialog box to change the markers used to define the plate, the thickness of the plate, and the radius of the corners of the plate. For more information, see Modifying Rigid Body Geometry on page 80.

Profile

Length

Radius

Thickness


Creating Parts42

Note: The reference marker of the plate determines the plate orientation and defines the plane of the plate to its x and y axes. ADAMS/View defines the x and y axes of the reference marker using the working grid, if it is turned on, or the view screen. ADAMS/View defines the plate vertices as the component of distance from the reference marker to the vertex marker as defined along the reference marker’s y-axis. Therefore, if you choose a plate vertex marker that is out-of-plane from the xy plane of the reference marker, the vertex marker is not the actual plate vertex.

To create a plate:

1 From the Geometric Modeling tool stack or palette, select the Plate tool .



■ If desired, set the thickness or radius of the corners of the plate.

3 Place the cursor where you want the first corner of the plate and click the mouse button.

4 Click at each corner of the plate. You must specify at least three locations.

5 Continue selecting locations or right-click to close the plate.

Note: If the distance between any two adjacent points is less than two times the radius of the corner, ADAMS/View cannot create the plate.


Creating Parts43

Creating an Extrusion

An extrusion is a three-dimensional object defined by its profile and depth. To create an extrusion, you draw a polyline that defines the extrusion’s profile. ADAMS/View extrudes the profile centered along the z-axis of the screen or working grid, if it is turned on. You can also specify the direction along the z-axis that ADAMS/View extrudes the profile.

Figure 15. Example of an Extrusion

Before you draw an extrusion, you can specify the following:

■ Whether you want a closed or open profile. If you close the profile, ADAMS/View creates a solid shape. If you leave the profile open, ADAMS/View creates a skin that has no mass properties.

■ Depth of the extrusion (referred to as its length).

■ Direction you want the profile to be extruded relative to the global coordinate system or working grid if you have it turned on. You can set the direction to one of the following:

■ Forward - Extrude the profile along the +z-axis.

■ About Center - Extrude the profile half the depth in both the +z and -z directions.

■ Backward - Extrude the profile along the -z-axis.

Figure 16 on page 44 shows the three different directions in which you can extrude a profile.

Note: You can also select Along Path, which lets you use the Extrusion tool to extrude wire geometry, such as a polyline. For more information, see Creating Complex Geometry.

Length

Drawing this profile ... Creates this extrusion


Creating Parts44

Figure 16. Example of Extrusion Directions

After you draw the extrusion, hotpoints appear at every vertex in the profile and at the point directly opposite from where you began drawing the profile. Use the vertex hotpoints to modify the profile of the extrusion and the opposite hotpoint to control the depth of the extrusion. For more information on modifying geometry using hotpoints, see Using Hotpoints to Graphically Modify Geometry on page 80.

You can also use the extrusion modify dialog box to more accurately place the points that make up the profile. You can also read in location points from a file. For more information, see Using Dialog Boxes to Precisely Modify Geometry on page 81, and Editing Locations Using the Location Table on page 102.

Note: You can only select to extrude a profile whose extrusion would have the following properties:

■ Same dimensions. For example, you cannot extrude a profile that would have mixed dimensions. See Figure 17 on page 45 for an example of an object with mixed dimensions.

■ Edge or face shared by only one face.

■ No intersecting lines.

Edge of working grid rotated about the y axis

Forward

About Center

Backward


Creating Parts45

Objects with these properties are called manifold. If the object extruded did not have these properties, it would be non-manifold. Some examples of non-manifold objects are shown in Figures 17 and 18. The figures show the dots of the profile that would create the extrusion.

If the result of an extrusion is an object that is non-manifold, you receive the following error message when you try to create the extrusion:

! ERROR: Creation of the feature failed! ERROR: The body created is non manifold.

Remake the profile so that it does not result in a non-manifold extrusion.

Figure 17. Example of Object with Mixed Dimensions

Figure 18. Objects with Shared Edges And Faces


Creating Parts46

To create an extrusion:

1 From the Geometric Modeling tool stack or palette, select the Extrusion tool .



■ Specify whether or not you want to create a closed extrusion.

■ If desired, set the length of the extrusion.

■ Specify the direction you want the profile to be extruded from the current working grid. See the beginning of this section on page 43 for an explanation of the different options.

3 Place the cursor where you want to begin drawing the profile of the extrusion and click.

4 Click at each vertex in the profile; then right-click to finish drawing the profile.


Creating Parts47

Creating a Revolution

A revolution is solid geometry created by revolving a profile. You specify the profile and the axis about which ADAMS/View revolves the profile. You cannot use existing construction geometry as the profile. ADAMS/View revolves the profile around the axis in a counterclockwise direction (right-hand rule).

Figure 19. Example of a Revolution

You can create an open or closed revolution. If you create a closed revolution, ADAMS/View closes the profile by drawing a line segment between the profile’ s first and last points and creates a solid revolution from this profile. If you leave the revolution open, ADAMS/View creates a skin that has no mass properties.

After you draw a revolution, hotpoints appear at the vertexes of the profile. They let you resize and reshape the revolution. For more information on modifying geometry using hotpoints, see Using Hotpoints to Graphically Modify Geometry on page 80.

You can also use the revolution modify dialog box to more accurately place the vertexes of the profile and read in location points from a file. For more information, see Using Dialog Boxes to Precisely Modify Geometry on page 81, and Editing Locations Using the Location Table on page 102.

Profile Linedefiningaxis

Drawing this profile ... Creates this revolution

Directionof revolution


Creating Parts48

To create a revolution:

1 From the Geometric Modeling tool stack or palette, select the Revolution tool .


■ Specify whether you want to create a new part or add the geometry to an existing part or ground.

■ Specify whether or not you want to create a closed extrusion.

3 Click at two points that define the axis about which ADAMS/View revolves the profile.

4 Click at the location of each vertex in the profile; then right-click to finish drawing the profile.

Note: Be sure to draw the profile so that it does not intersect the line you drew defining the axis of revolution.


Creating Parts49

Creating Complex GeometryADAMS/View provides you with many ways in which you can take simple geometry and create complex geometry from it. You can create solid geometry that has mass from wire geometry or create complex, open geometry that has no mass. The following sections explain how to create complex, solid geometry.

■ Chaining Wire Construction Geometry, 49

■ Extruding Construction Geometry, 50

■ Combining Geometry, 52

Chaining Wire Construction Geometry

You can link together wire construction geometry to create a complex profile, which you can then extrude. The geometry to be chained together must touch at one endpoint and cannot be closed geometry. ADAMS/View adds the final chained geometry to the part that owns the first geometry that you selected.

Note: If you want to use the chained geometry with a pin-in-slot or curve-to-curve constraint, you must turn the geometry into a spline, as explained in Creating Splines on page 28.

To chain wire geometry together:

1 If necessary, create the wire geometry as explained in Creating Construction Geometry on page 18.

2 From the Geometric Modeling tool stack or palette, select the Chain tool .

3 Click each piece of the wire geometry to be chained. The Dynamic Model Navigator highlights those objects in your model that can be chained as you move the cursor around the main window.

4 After selecting the geometry to be chained, right-click to create the chained geometry.


Creating Parts50

Extruding Construction Geometry

You can add thickness to wire geometry by extruding it to create three-dimensional geometry. You can extrude lines, polylines, polygons, and wire geometry that you have chained together. You cannot extrude points. If the geometry you extrude is closed, ADAMS/View creates solid geometry that has mass. ADAMS/View centers the extruded geometry about the z-axis of the view screen or working grid, if it is turned on.

When you extrude geometry, you select the geometry that you want to extrude, called the profile geometry, and then you select the wire geometry that defines the path along which you want to extrude the profile. The following shows a polygon extruded along the path of a line.

Figure 20. Example of Extruding Construction Geometry

The geometry you extrude can be a new part or belong to another part, which you specify when you extrude the geometry.

Refer also to the note on creating extrusions on page 44.

creates this partExtruding this geometry ...

Path along whichit is to be extruded

Profile to be extruded


Creating Parts51

To extrude wire geometry:

1 If necessary, create the wire geometry as explained in Creating Construction Geometry on page 18.

2 From the Geometric Modeling tool stack or palette, select the Extrude tool .

3 In the settings container, specify the following. You can ignore all other settings:

■ Specify whether you want to create a new part composed of the extruded geometry or add the geometry to an existing part or ground.

■ Select Along Path.

4 Select the wire geometry to be extruded.

5 Select the wire geometry defining the path along which you want to extrude the geometry.


Creating Parts52

Combining Geometry

Once you have created individual parts of solid geometry, you can combine them into one part to create complex, solid geometry, referred to as constructive, solid geometry or CSG. ADAMS/View creates the solid geometry using Boolean operations, such as union and intersection. The next sections explain how to combine geometry:

■ Creating One Part from the Union of Two Solids, 53

■ Creating One Part from the Intersection of Two Solids, 54

■ Cutting a Solid from Another Solid, 55

■ Splitting a Solid, 56


Creating Parts53

Creating One Part from the Union of Two Solids

ADAMS/View lets you create complex geometry by joining two intersecting solids. ADAMS/View merges the second part you select into the first part resulting in a single part. The union has a mass computed from the volume of the new solid. Any overlapping volume is only counted once.

Figure 21. Example of the Union of Solids

To create a part from the union of two solids:

1 From the Geometric Modeling tool stack or palette, select the Union tool .

2 Select the solid geometry to be combined. As you move the cursor, the Dynamic Model Navigator highlights those objects that can be combined. The second part you select is combined into the first part.

Combining these solids ... creates one part


Creating Parts54

Creating One Part from the Intersection of Two Solids

ADAMS/View lets you intersect the geometry belonging to two solids to create a single part made up of only the intersecting geometries. ADAMS/View merges the second part that you select with the geometry of the first part that you select and forms one rigid body from the two geometries.

Figure 22. Example of the Intersection of Solids

To create a part from the intersection of two overlapping solids:

1 From the Geometric Modeling tool stack or palette, select the Intersect tool .

2 Select the solid geometry to be combined. As you move the cursor, the Dynamic Model Navigator highlights those objects that can be combined. The second part you select is combined into the first part.

Intersecting these solids ... creates this part


Creating Parts55

Cutting a Solid from Another Solid

ADAMS/View lets you remove the volume where one solid intersects another solid to create a new solid. ADAMS/View subtracts the geometry of the second part that you select from the geometry of the first part. The remaining geometry belongs to the second part that you selected.

Figure 23. Example of Cutting a Solid

You cannot cut the geometry so that the remaining geometry is split into two solids. For example, you cannot cut a block from the center of a cylinder so that two cylinders remain after the cut as shown below.

Figure 24. Example of Cutting a Solid into Two Solids

If a part completely envelopes another part, you cannot cut that part from the enveloped part because no geometry would result. For example, if a box completely envelopes a sphere, you cannot cut the box from the sphere and leave a zero mass part.

Cutting common volume ... creates this geometry

Common volume to be removed

Result of this split would be two solids

Box to becut from cylinder


Creating Parts56

Figure 25. Example of Cutting a Solid into a Zero-Mass Part

To create a part from the difference of two solids:

1 From the Geometric Modeling tool stack or palette, select the Cut tool .

2 Select the solid geometry to be cut. As you move the cursor, the Dynamic Model Navigator highlights those objects that can be cut. The second part you select is cut from the first part.

Splitting a Solid

After you’ve created a complex solid, often referred to as a CSG, using the Boolean operations explained in the previous sections, you can split the complex solid back into its primitive solids. ADAMS/View creates a part for each solid resulting from the split operation.

To split a complex solid:

1 From the Geometric Modeling tool stack or palette, select the Split tool .

2 Select the solid geometry to be split. The Dynamic Model Navigator highlights those objects in your model that can be split.

Result of this split would be a solid with zero mass

Box to becut from sphere


Creating Parts57

Adding Features to Geometry

You can add features to the solid geometry that you create, including chamfering the edges of the geometry, adding holes and bosses, and hollowing out solids. The next sections explain how to add features to solid geometry:

■ Chamfering and Filleting Objects, 57

■ Adding Holes and Bosses to Objects, 59

■ Hollowing Out a Solid, 60

Chamfering and Filleting Objects

You can create different types of edges and corners on your solids. These include beveled (chamfered) edges and corners and rounded (filleted) edges and corners. You can think of creating filleted edges as rolling a ball over the edges or corners of the geometry to round them. The example below shows chamfered and filleted edges and corners.

Figure 26. Chamfered and Filleted Edges and Corners

When chamfering an edge or corner, you can set the width of the beveling. When filleting an edge or corner, you can specify a start and an end radius for the fillet to create a variable fillet. ADAMS/View begins creating the variable fillet using the start radius and then slowly increases or decreases the size of the fillet until it reaches the end radius. Using the ball analogy again, ADAMS/View starts rounding edges and corners using one size ball and finishes using a different size.

Chamfered Filleted edgesedges and

corner and corner


Creating Parts58

Figure 27 shows a variable fillet. The end radius is three times larger than the start radius.

Figure 27. Variable Radius Fillet Edge

Note: You will get different results when you chamfer or fillet one edge at a time than when you chamfer or fillet all edges at once. Also, you may not be able to chamfer or fillet an edge if an adjoining edge has already been chamfered or filleted. It depends on the complexity of the filleting or chamfering.

To create a chamfered or fillet edge:

1 From the Geometric Modeling tool stack or palette, select either of the following tools:

■ To create a chamfered edge or corner, select the Chamfer tool .

■ To create a fillet edge or corner, select the Fillet tool .

2 In the settings container, do one of the following:

■ If desired, for chamfers, specify the width of the bevel.

■ If desired, for fillets, specify the radius. To create a variable fillet, also select End Radius and enter the end radius. ADAMS/View uses the value you enter for radius as the starting radius of the variable fillet.

3 Select the edges or vertices to be chamfered or filleted. The edges and vertices must be on the same rigid body.

4 Right-click.

Startradius

End radius


Creating Parts59

Adding Holes and Bosses to Objects

You can create circular holes in solid objects and create circular protrusions or bosses on the face of solid objects. Examples of a hole and boss on a link are shown below.

Figure 28. Examples of Holes and Bosses

As you create a hole, you can specify its radius and depth. As you create a boss, you can specify its radius and height.

To create a hole or boss:

1 From the Geometric Modeling tool stack or palette, select either of the following tools:

■ To create a hole, select the Hole tool .

■ To create a knob, select the Boss tool .

2 In the settings container, do one of the following:

■ If desired, for holes, specify the radius and depth of the hole.

Note: You cannot specify the radius and depth of a hole so that it splits the current geometry into two separate geometries.

■ If desired, for bosses, specify the radius and height.

3 Select the face of the body on which you want to create the hole or boss.

4 Click the location where you want to center the hole or boss.

Tip: To create a hole or boss at a specific location, create a temporary marker at the desired location for the hole or boss, and select it in Step 4.

Link with hole Link with boss


Creating Parts60

Hollowing Out a Solid

You can hollow out one or more faces of a solid object to create a shell. As you hollow an object, you can specify the thickness of the remaining shell and the faces to be hollowed. You can also specify that ADAMS/View add material to the outside of the object. In this case, ADAMS/View uses the original object as a mold. ADAMS/View adds material of the specified thickness to the original object and then takes the original object away leaving a shell.

The following shows two hollowed boxes. One box was hollowed from the inside; the other box was hollowed by adding material to the outside.

Figure 29. Examples of Hollowed Boxes

The resulting dimensions of the boxes are shown Figure 30.

Box hollowed from inside Box with material added to outside


Creating Parts61

Figure 30. Hollowed Box Dimensions

Note: You can hollow any object that has a face. You cannot hollow spheres, revolutions, or wire construction geometry.

To hollow an object:

1 From the Geometric Modeling tool stack or palette, select the Hollow tool .


■ If desired, specify the thickness of the remaining shell after you hollow the object.

■ If you want to add the shell to the outside of the object, clear the check box Inside.

3 Select the solid body that you want to hollow.

4 Select the faces of the body that you want to hollow. The Dynamic Model Navigator highlights those faces in your body that can be selected.

5 Click the right mouse button to hollow the selected faces.

Original boxdimensions

Box hollowedfrom inside

Box hollowedwith material

t = thicknessh = heightw = width

added to outside

w

h h

w

h - 2t

l - 2t

w + 2t

w

h + 2t h

Key:


Creating Parts62

Merging GeometryADAMS/View lets you merge two non-intersecting rigid body geometry into one without performing any Boolean operations on the geometry. The geometry can contain any type of geometry, solid, wire, or complex. The geometry can also belong to the same part. If the geometry belongs to the different parts, ADAMS/View merges the parts into one.

Since ADAMS/View does not perform any Boolean operations on the merged geometries, overlapping volumes produce double-density mass in the part and change the results of the mass property calculations. Therefore, you should use this operation

only for non-intersecting rigid bodies that the Union tool cannot combine.

ADAMS/View merges the second geometry that you select into the first geometry you select.

To merge two rigid body geometry:

1 From the Geometric Modeling tool stack or palette, select the Merge tool .

2 Select the geometry to be merged. The Dynamic Model Navigator highlights those objects in your model that can be merged as you move the cursor around the modeling window. The second geometry that you select is combined into the first.

ADAMS/View combines the selected geometry and deletes the second.


Creating Parts63

Working with Flexible LinksA discrete flexible link consists of two or more rigid bodies connected by beam force elements. You indicate the following and ADAMS/View creates the appropriate parts, geometry, forces, and constraints at the endpoints:

■ Endpoints of the link

■ Number of parts and the material type

■ Properties of the beam

■ Types of endpoint attachments (flexible, rigid, or free)

Figure 31 shows a flexible link composed of rigid bodies whose cross-section geometry is rectangular.

Figure 31. Discrete Flexible Link

For more information on beam force elements, see Adding a Massless Beam on page 244. Also note the caution about the asymmetry of beams explained in that section.

The following sections explain more about discrete flexible links and how you create and modify them.

■ Types of Flexible Link Geometry, 64

■ Positioning Flexible Links, 65

■ Creating a Flexible Link, 67

■ Modifying Flexible Links, 73

Part A

Part B

Fixed attachment

Flexible

Parts

attachment

Beams


Creating Parts64

Types of Flexible Link Geometry

To make it convenient to create discrete flexible links, ADAMS/View provides a set of geometry you can select for the cross-section of the link. If the pre-defined geometry does not meet your needs, you can also define your own cross-section based on area and inertia properties that you enter. If you enter area and inertia properties yourself, ADAMS/View creates short angular geometry to represent the link.

The pre-defined cross-section geometry that you can select includes:

■ Solid rectangular

■ Solid circular

■ Hollow rectangular

■ Hollow circular

■ I-beam

ADAMS/View uses the cross-section geometry to calculate the following:

■ Area and area moments of inertia (Ixx, Iyy, Izz) for the beams.

■ Mass, mass moments of inertia (Ixx, Iyy, Izz), and center-of-mass markers for the rigid bodies.

Note that ADAMS/View does not directly use the geometry to account for stress on the beam. Therefore, any stress values are based on the area and area moments.


Creating Parts65

Positioning Flexible Links

You use two or three markers to define the locations and orientation of a discrete flexible link: Markers 1 and 2 and an orientation marker, which is required for only certain types of cross-section geometry.

Figure 32 shows how Marker 1, Marker 2, and the orientation marker are used to position the part geometry and the beam forces.

Figure 32. Orientation Marker Used to Orient Non-Axisymmetric Cross-Sections

As you can see from the figure, Markers 1 and 2 define the total length of the flexible link and the x (longitudinal) direction of the associated beam forces. ADAMS/View creates new markers on top of Markers 1 and 2, as well as at the centers-of-mass of the geometry associated with the discrete flexible link. For the resulting beams, the vector from Marker 1 to Marker 2 defines the x-axis while the vector from Marker 1 to the orientation marker defines the xz-plane. The global axes are not relevant to the orientation of the beam forces unless you erroneously specify three co-linear markers.

Orientationmarker

If you input: The result is:

Number of segments: 2Section: Solid rectangularBase: 50 (along yJ)Height: 10 (along zJ)Ends: free-freeMarkers as shown below:

Marker 1

Marker 2

zG

xGyG

10

50

yG xG

zG

y

xz

y

xz

J Marker

I Marker


Creating Parts66

Table 1 shows how the number of beams that get created for your flexible link depends on the number of segments and the types of endpoint attachments.

For links with axisymmetric cross-sections, such as solid and hollow circular sections, the orientation of the cross section is not critical and so ADAMS/View does not require the use of an orientation marker.

Table 1. Relationship Between Beams, Segments, and Endpoint-Attachment Types

Types of endpoint attachments: Number of beams created:

Free-Free Number of segments − 1

Rigid-Rigid Number of segments − 1

Free-Rigid or Rigid-Free

Number of segments − 1

Flexible-Free or Free- Flexible

Number of segments

Flexible-Rigid or Rigid-Flexible Number of segments

Flexible-Flexible Number of segments + 1


Creating Parts67

Creating a Flexible Link

To create a flexible link:

1 From the Build menu, point to Flexible Bodies, and then select Discrete Flexible Link.

The Discrete Flexible Link dialog box appears.

2 Define the overall properties of the flexible link as explained in Table 2.

Table 2. Overall Flexible Link Property Options

To specify: Do the following:

Name for parts, constraints, forces, and markers

In the Name text box, enter a text string of alphanumeric characters. ADAMS/View prepends the text string you specify to the name of each object it creates. For example, if you specify the string LINK, the first rigid body is LINK_1, the first marker is LINK_MARKER_1, and so on.

Type of material

In the Material text box, enter the type of material to be used for the rigid bodies and beam properties.

To browse for a material type in the Database Navigator or create a new material, right-click the Material text box, and then select the appropriate command. For more information on material types, see Setting Up Materials on page 118.

Number of segments

Enter the number of rigid bodies that you want in the link.

Damping ratio In the Damping Ratio text box, enter the ratio of viscous damping to stiffness for the beam forces.

Color In the Color text box, enter the color to be used for the geometry in the flexible link.

To browse for a color in the Database Navigator or create a new color, right-click the Color text box, and then select the appropriate command.


Creating Parts68

3 Define the length of the link and its flexibility at its ends as explained in Table 3.

Table 3. Length and Flexibility Options

To specify: Do the following:

Ends of the link Enter the markers that define the endpoints of the link in the Marker 1 and Marker 2 text boxes. Marker 1 defines the start of the link and Marker 2 defines the end of the link. Marker 1 and Marker 2 are also used to calculate the orientation of the link. See Positioning Flexible Links on page 65 for more information.

Flexibility at the ends of the link

Select how to define the ends of the link from the Attachment option menus. You can select the following for each end of the link:

■ free - The end is unconnected.

■ rigid - A fixed joint is created between the parent of Marker 1 and the first part of the discrete flexible link or between the parent of Marker 2 and the last part of the discrete flexible link.

■ flexible - The link has discrete flexibility all the way to the endpoint. To create this flexibility, ADAMS/View creates an additional beam force between the first or last segment of the link and the parent part of Marker 1 or Marker 2. The length of the beam is one half of the segment length.


Creating Parts69

4 Select and define the geometry of the link or specify the area and area moments of inertia of the flexible link as explained in Table 4 and select OK.

Table 4. Flexible Link Cross-Section Geometry Options

To create: Specify the following: Example:

Solid rectangle

■ Orient Marker - The marker that defines the orientation (z-axis) of link. See Positioning Flexible Links on page 65 for information on setting the orientation of the geometry.

■ Base - The width of the rectangle (dimension in local y direction).

■ Height - The height of the rectangle (dimension in local z direction).

Solid circle Diameter - Diameter of the circular cross-section.

Hollow rectangle

■ Orient Marker - The marker that defines the orientation (z-axis) of the link. See Positioning Flexible Links on page 65 for information on setting the orientation of the geometry.

■ Base - The outer width of the rectangular shell.

■ Height - The height of the outer rectangular shell.

■ Thickness - Uniform width of the wall of the rectangular shell.

Height

Base

z

y

Diameter

Base

Height

Thickness z

y


Creating Parts70

Hollow circle

■ Diameter - Outer diameter of the circular shell.

■ Thickness - Width of the wall of the circular shell.

I-beam ■ Orient Marker - The marker that defines the orientation of the link. See Positioning Flexible Links on page 65 for information on setting the orientation of the geometry.

■ Base - Enter the width of the I-beam.

■ Height - Enter the height of I-beam.

■ Flange - Enter the width of the flange of the I-beam.

■ Web - Enter the width of the web of the beam.

Table 4. Flexible Link Cross-Section Geometry Options (continued)


Diameter

Thickness

Height

Base

Web

Flangez

y


Creating Parts71

Your own custom-shaped cross-section

■ Orient Marker - The marker that defines the orientation (z-axis) of the link. For information on setting the orientation of the link, see Positioning Flexible Links on page 65.

■ X Section Area - Specify the uniform area of the beam cross section. The centroidal axis must be orthogonal to this cross section.

■ Link Mass - Enter the total mass of all the link segments combined.

Note: The example of an elliptical cross-section is only one example of many cross-sections that you can create using the Properties option.



Area = πab

a

Ixx = 1/4πab(a2 + b2)

Iyy = 1/4πab3

Izz = 1/4πa3b

b

z

y


Creating Parts72

Properties (continued)

■ Link Segment Inertias - Specify the area moments of inertia for the link.

❖ Ixx - Enter the torsional constant, also referred to as torsional shape factor or torsional stiffness coefficient. It is expressed as unit length to the fourth power. For a solid circular section, Ixx is identical to the polar moment of inertia

J=(πr4/2). For thin-walled sections, open sections, and noncircular sections, consult a handbook.

❖ Iyy, Izz - Enter the area moments of inertia about the neutral axes of the beam-cross sectional areas (y-y and z-z). These are sometimes referred to as the second moments of area about a given axis. They are expressed as unit length to the fourth power. For a solid circular section, Iyy=Izz=

(πr4/4). For thin-walled sections, open sections, and noncircular sections, consult a handbook.




Creating Parts73

Modifying Flexible Links

Once you create a link, you must modify each object separately, such as each beam and rigid body. Therefore, you might find it easier to delete the beam and create it again instead of modifying each object individually.

If you find that link does not bend enough, investigate your cross-section and material properties and possibly increase the number of segments in the link.

Working with Point MassesPoint masses are points that have mass but no inertia properties or angular velocities. They are computationally more efficient when rotational effects are not important.

For example, you could use point masses to represent the concentrated masses in a net. You could then represent the ropes between the masses as forces or springs. Figure 33 shows a model of a net with point masses.

Figure 33. Point Mass Net Example


Creating Parts74

To create or modify a point mass:

1 From the Build menu, point to Point Mass, and then select either New or Modify.

2 If you selected Modify, the Database Navigator appears. Select a point mass to modify. For more information on the Database Navigator, see Navigating Through a Modeling Database on page 147 of the guide, Learning ADAMS/View Basics.

The Create or Modify Point Mass dialog box appears. Both dialog boxes contain the same options.

3 If you are creating a point mass, enter a name for the point mass.

4 Set the mass of the point mass in the dialog box and adjust its location as desired. By default, ADAMS/View places the point mass in the center of the main window with a mass of 1 in current units.

5 Select the Comments tool on the dialog box and enter any comments you want associated with the point mass. For more information on entering comments, see Adding Comments to Objects on page 183 of the guide, Learning ADAMS/View Basics.

6 Select OK.


Creating Parts75

Creating a Spline from a TraceTraces follow the motion of a point or part (circle or cylinder) as it moves relative to a second part. From these traces, ADAMS/View can create two- or three-dimensional splines depending on the geometry of the parts that you select to be traced. Traces can be helpful when you know the movement that a part should follow and, from this, you want to determine the geometry of the part.

The following sections tell you more about creating spline geometry from traces:

■ Example of Creating Spline Geometry, 75

■ Types of Spline Geometry Created from Trace, 76

■ Creating Spline Geometry, 77

Example of Creating Spline Geometry

For example, if you want to create a surface on a cam that makes a follower part move in a particular way relative to each other, you can create the necessary surface geometry by following the movement of the two parts with a trace that ADAMS/View turns into spline geometry.

You start creating the spline geometry by first making the follower and cam move the way you want them to relative to each other. You place a motion on the cam joint that rotates the cam once per second. Next, you place a motion on the follower joint that moves it up and down once each second.

After simulating the motion, you then request ADAMS/View to trace the motion of the follower circle relative to the cam circle and create spline geometry based on that geometry. Figure 34 shows the cam and follower geometry and the trace that ADAMS/View creates.


Creating Parts76

Figure 34. Follower and Cam with Trace Geometry

Types of Spline Geometry Created from Trace

You can create two- or three-dimensional splines from traces. A trace that follows a point creates a three-dimensional spline. The point can move in any direction relative to the part on which the trace was created.

A trace that follows a circle or cylinder creates a two-dimensional spline. ADAMS/View creates the curve in the xy plane of the base marker (the marker on the part on which the trace was created). ADAMS/View assumes the circle is parallel to the plane or the cylinder is perpendicular to the plane, and that the motion is in this plane.

When you create the trace, ADAMS/View creates a base marker that is oriented properly with respect to the circle or cylinder you selected. Therefore, the curve will be in the plane of the circle in its initial position. You have to make sure that the motion is in the plane of the circle or you will get unexpected results. Therefore, be sure to think of the circle trace as occurring in the plane of the circle. It can be any plane, not necessarily the global xy plane.

Follower Trace

Cam


Creating Parts77

Creating Spline Geometry

To create a spline from a trace:

1 Set up your model so that it creates the desired motion after which you want the spline to be fashioned.

2 Run a simulation of your model as explained in Performing an Interactive Simulation on page 86 of the guide, Simulating Models in ADAMS/View.

3 Reset the simulation by selecting the Simulation Reset tool from either the Simulation container on the Main toolbox or the Simulation palette.

Note: Be sure to reset your model. You cannot easily select objects when the screen is in simulation mode.

4 From the Review menu, select Create Trace Spline.

5 Select a point, marker, circle, or cylinder with which to trace and then select the part on which to trace.

You can trace on ground or any other part. For a point trace, select anywhere on the point or part. For a circle or cylinder, however, be careful where you select because where you select on the circle and the part determines the resulting trace geometry. There are usually two possible traces, one on each side of the circle or cylinder.

6 Replay the simulation to see the selected object follow the trace curve.


Creating Parts78

Tips: The following are some tips on creating splines from traces:

■ When you trace an object, the point/circle should move in a smooth, even path or the trace ends up looking like scribbles on the screen.

■ If the path is closed, you should simulate for one cycle only.

■ If the trace is uneven or complex, you can get a strange looking curve as a result. As an alternative to the Create Trace Spline menu command, you can use the Command Navigator to execute the command: geometry create curve point_trace. It lets you create a polyline instead of a spline, which works better if the trace is uneven or complex. In that case, the motion of the cam or slot is transferred through the traced curve and gives the desired follower motion.

3 Modifying Parts

OverviewParts define the objects in your model that can have mass and inertia properties and can move. All forces and constraints that you define in your model act on these parts during a simulation. This chapter explains how to create and modify parts. It contains the following sections:

■ Modifying Rigid Body Geometry, 80

■ Calculating Aggregate Mass of Parts, 120

■ Measuring Distances Between Markers, 122


Modifying Parts80

Modifying Rigid Body GeometryYou can modify the geometry of a rigid body using:

■ Hotpoints that appear on the geometry when you select it. Hotpoints let you graphically change the shape of the geometry.

■ A dialog box to enter information about the geometry, such as the location of anchor points, its width, or its depth. In addition, some dialog boxes let you easily edit profile point locations through a Location Editor.

The next sections explain how to modify geometry.

■ Using Hotpoints to Graphically Modify Geometry, 80

■ Using Dialog Boxes to Precisely Modify Geometry, 81

■ Editing Locations Using the Location Table, 102

Using Hotpoints to Graphically Modify Geometry

You can use hotpoints to resize and reshape the geometry of a rigid body. The hotpoints appear at various locations on the geometry depending on the type of geometry. Figure 35 shows examples of hotpoints on common types of geometry. Refer to the sections on creating geometry to see where ADAMS/View places hotpoints on the different types of geometry.

Figure 35. Examples of Hot Points

To display hotpoints on geometry:

■ Click the geometry using the left mouse button.


Modifying Parts81

To use the hotpoints to resize and reshape geometry:

■ Drag the hotpoint to the desired location and release the mouse button.

Figure 36. Examples of Resizing and Reshaping Geometry

Using Dialog Boxes to Precisely Modify Geometry

You can precisely control the size, location, and shape of rigid body geometry using modify dialog boxes. In addition, you can change the name of the geometry as you modify it.

To modify a point, you use the Table Editor since a point only consists of a location. For more information on editing objects using the Table Editor, see Editing Objects Using the Table Editor on page 401. In addition, for lines, polylines, extrusions, and revolutions, there is a Location Editor that lets you edit the locations of profile points. For more information, see Editing Locations Using the Location Table on page 102.

Dragging this hotpoint ... resizes this box

Dragging this hotpoint ... reshapes this polygon


Modifying Parts82

To see all the different types of geometry that make up a part:

■ Place the cursor on a part and hold down the right mouse button.

ADAMS/View displays the names of the geometry near the cursor location. If it is a very complex part, you may need to move the cursor to different locations on the part to see all the different types of geometry.

Tip: You can also use the Info command to view the geometry that belongs to a part. For more information, see Viewing Modeling Information on page 171 of the guide, Learning ADAMS/View Basics.

To display a modify dialog box for geometry and modify geometry:

1 Place the cursor over the part containing the geometry and hold down the right mouse button.

2 Point to the name of the geometry that you want to modify and then select Modify.

The modify dialog box for the geometry appears.

3 Change the name of the geometry, if desired, and assign a unique ID number to the geometry, if appropriate. The ID is an integer used to identify the element in the ADAMS/Solver dataset (.adm) file. You only need to specify an ID number if you are exporting the model to an ADAMS/Solver dataset, and you want to control the numbering scheme used in the file.

Enter a positive integer or enter 0 to have ADAMS set the ID for you.

Lists geometry in the part


Modifying Parts83

4 Add any comments about the geometry that you want to enter to help you manage and identify the geometry. You can enter any alphanumeric characters. The comments that you create appear in the information window when you select to display information about the object, in the ADAMS/View log file, and in a command or dataset file when you export your model to these types of files.

To enter comments for extrusions, revolutions, lines, and polylines, select the

Comments tool at the bottom of the dialog box. The Comments dialog box

appears. For more information, see Adding Comments to Objects on page 183 of the guide, Learning ADAMS/View Basics.

5 Enter the values for the geometry as explained in Tables 5, 6, and 7 and select OK.


Modifying Parts84

Table 5. Elements You Can Modify for Construction Geometry

To modify: Enter values for:

Markers ■ Location or Node Id - Specify either:

■ Location of the marker. ADAMS/View applies your location coordinates in the coordinate system in the Relative To text box.

■ Node ID on a flexible body that ADAMS/View uses to determine the location at which it will place a marker. The value must be an integer that is a valid node ID from your flexible part.

Note that you can only create markers on flexible bodies at the node locations, so use the Node ID parameter to ensure a valid location.

■ Orientation, Along Axis Orientation, or In Plane Orientation - Specify either of three orientation methods and their appropriate values as explained in the next items.

■ Orientation - Orientation of marker using three rotation angles. ADAMS/View orients the marker starting from the initial coordinate system and applying three successive rotations.

Depending on the convention you select, the rotations occur about space-fixed or body-fixed axes in any combination of the x, y, and z axes. By default, you supply body 313 (body-fixed z, x, z) angles. You can change this convention as explained in Specifying the Type of Coordinate System on page 30 of the guide, Learning ADAMS/View Basics.

ADAMS/View applies your orientation angles with respect to the coordinate system in the Orientation Relative To text box.


Modifying Parts85

Markers (continued)

■ Along Axis Orientation - Orientation of a marker by directing one of its axes. ADAMS/View assigns an arbitrary rotation about the axis.

Two points are needed to define an axis but you can enter either one or two points to direct the axis. If you enter two points, the axis points from the first location to the second. If you enter one point, ADAMS/View uses the location you specified in the Location text box as the first point and the new location as the second point.

Figure 37. Along Axis Orientation

ADAMS/View applies the location coordinates in the coordinate system you identify using the Location Relative To parameter.

Note that this does not completely dictate the orientation of the coordinate system. ADAMS/View positions the coordinate system with an arbitrary rotation about the axis. If you must completely control the coordinate system orientation, select Orientation or In Plane Orientation.

By default, you direct the z-axis of the coordinate system. You can use the DEFAULTS ORIENT_AXIS_AND_PLANE AXIS_AND_PLANE_SETTING command to change this convention. For example, selecting either X_AXIS_XY_PLANE or X_AXIS_XZ_PLANE directs the x-axis. The plane-convention setting does not affect this parameter.

You can also direct the axis graphically using the marker’ s position handle. Simply point the appropriate axis on the marker in the desired direction. For more information, see Translating and Rotating Objects Using Position Handle on page 443.

Table 5. Elements You Can Modify for Construction Geometry (continued)


Point 1

Point 2

Axis


Modifying Parts86

Markers (continued)

■ In Plane Orientation - Orientation of the marker by directing one of the axes and locating one of the coordinate planes.

Figure 38. In Plane Orientation

To define an axis and a plane, you need three points. You can enter either two or three locations, however. If you enter three locations, the axis points from the first location to the second and the plane is parallel to the plane defined by the three locations. If you enter only two locations, ADAMS/View uses the location you specified in the Location text box as the first point and the other two locations as the second and third points.

ADAMS/View applies the location coordinates in the coordinate system in the Relative To text box.

By default, you direct the z-axis of the coordinate system marker and locate the zx plane. You can use the DEFAULTS ORIENT_AXIS_AND_PLANE AXIS_AND_PLANE_SETTING command to change this convention. For example, selecting X_AXIS_XY_PLANE directs the x-axis and orients the xy plane.

■ Location Relative To - The coordinate system in which you specify the location and orientation coordinates. If you do not specify this parameter, ADAMS/View uses the default coordinate system.



Point 1

Point 2Axis

Point 3

Plane


Modifying Parts87

Lines/Polylines

■ Relative To - The coordinate system in which you specify the location and orientation coordinates. If you do not specify a coordinate system, ADAMS/View uses the default coordinate system.

■ From the option menu, select Location or Path Curve and then specify either:

■ Locations to be used to define the polyline. By default, you supply Cartesian (x, y, z) coordinates. ADAMS/View applies the location coordinates in the coordinate system you identify using the Relative To parameter.

To easily edit the locations, select the More button to display the Location Table. For more information on using the Location Table, see Editing Locations Using the Location Table on page 102.

■ A geometry object whose path defines the polyline. You can select arcs, circles, spline curves, polylines, and outlines. ADAMS/View extracts the values of the vertices of the path curve and uses them to create the polyline.

■ Close - Select either:

■ yes - Creates a closed polyline. If closed, the polyline can be filled (shaded). The endpoints of the polyline do not need to be coincident for you to close it; the two endpoints will be connected with a line segment.

■ no - Creates a polyline that appears as a segmented curve. ADAMS/View creates the polyline by connecting the locations you specified in the Location text box together with straight line segments in the order in which you specified them.




Modifying Parts88

Arcs and circles

■ Center Marker - Marker at the center of the arc or circle. Orient the center marker so that its z-axis is normal to the plane of the circle or arc.

■ Angle Extent (arcs only) - Extended angle measured positive (according to the right-hand rule) about the z-axis of the center marker of an arc. The angle starts at the positive x-axis of the center marker and extends the arc.

Figure 39. Angle Extent

■ Radius or Ref Radius By Marker - Enter either the radius of the arc or circle or enter a radius marker. If you specify a radius marker, ADAMS/View calculates the radius of the arc or circle as the distance from the center marker origin to the radius marker origin. ADAMS/View stores the radius value, not the marker name. If you later move the marker, the radius does not change.

■ Segment Count - Number of straight line segments ADAMS/View uses to draw the circle or arc.



θ

y

x

z

Angle Extent


Modifying Parts89

Arcs and circles (continued)

■ Close - For an arc, select either:

■ Chord - Closes the arc from the starting point to the ending point.

■ Sector - Closes the arc so that it creates a pie-shaped arc.

■ No - Creates an open arc.

■ Yes - Closes the arc from the starting point to the ending point.

Figure 40. Close Options



x

y

Chordx

Sectorx

Nox

Yes

Start

EndEndEnd End

StartStart Start

y yy


Modifying Parts90

Splines ■ Closed - Whether or not the spline is closed (yes) or open (no).

■ Segment Count - Specifies the number of segments ADAMS/View uses to graphically display the fitting of the points in the curve. To have ADAMS/View calculate the number of default number of segments

automatically, select the Calculate button.

For an open curve, ADAMS/View defaults to a segment count that is five times the number of curve points that you have provided. Specifying fewer segments results in a coarser curve. For a closed curve, ADAMS/View defaults to a segment count that is five times the number of points plus one. In mathematical terms:

5 * ( #pts + 1 )

For both closed and open curves, there are no limits to how many and how few segments you use (other than hardware limitations), but for every curve there is a plateau, beyond which increasing the number of segments does not enhance the graphics of your spline.

■ Values - Locations of the points that define the spline. The points are relative to the reference marker.To edit the locations of the points, select the More button to display the Location Table. For more information on using the Location Table, see Editing Locations Using the Location Table on page 102.




Modifying Parts91

Spline (continued)

■ Reference Marker - Marker that defines the location and orientation of the spline. The marker acts as a reference coordinate system for the coordinate values used to define the reference curve points.

■ Reference Curve - Existing data element curve that is used to mathematically define the spline. When you define the points that make up the spline, ADAMS/View creates a curve fit through the points.

■ Reference Matrix - A data element matrix that contains all the spline point coordinates. For more information on data element matrixes, see Using the General Method on page 347.




Modifying Parts92

Table 6. Elements You Can Modify for Solid Geometry

To modify: Specify:

Boxes ■ Corner Marker - A marker used to define the anchor point for the box.

■ Diag Corner Coords - Location of the diagonal corner from the marker measured in the coordinate system of the corner marker.

Figure 41. Box Modify Options

Planes ■ Ref Marker Name - Reference marker used to locate and orient the plane.

■ X Minimum, Y Minimum - The location of one corner of the plane in coordinates relative to the reference marker. If all values are positive, the values indicate the lower left corner of the plane. For example, the values of X Minimum = 10 and Y Minimum = 20, place the lower left corner at 10,20 in the reference marker’s coordinate system.

■ X Maximum, Y Maximum - The location of the opposite corner of the plane in coordinates relative to the reference marker. If all values are positive, the values indicate the upper right corner of the plane.

Cornermarker

Diagonal cornercoordinates


Modifying Parts93

Cylinders The options for modifying a cylinder as explained below. The options are also shown in the Figure 42.

Figure 42. Cylinder Options

■ Center Marker - Center marker that defines the center of base of the cylinder.

■ Angle Extent - Extended angle measured positive (according to the right-hand rule) about the z-axis of the center marker. The angle starts at the positive x-axis of the center marker and extends the arc of the cylinder.

■ Length - Length of the cylinder. ADAMS/View uses the value of length to specify the z distance between the two circles. A positive value specifies a cylinder along the positive z-axis of the center marker.

Table 6. Elements You Can Modify for Solid Geometry (continued)

To modify: Specify:

Length

Radius

z

y

x Center marker


Modifying Parts94

Cylinders (continued)

■ Radius or Ref Radius By Marker - Radius of circles at top and bottom of cylinder or a radius marker. If you enter a radius marker, ADAMS/View calculates the radius of the cylinder as the distance from the center marker z-axis to the radius marker. ADAMS/View stores the radius value, not the marker name. If you later move this marker, the radius does not change.

■ Side Count For Body - Number of flat sides ADAMS/View draws on the side of the cylinder. The number of sides you specify affects the calculations ADAMS/View uses to determine a part’s mass and inertia. See Modifying Mass and Inertia for Rigid Bodies on page 108.

■ Segment Count For Ends - Number of straight line segments ADAMS/View uses to draw the circles at the ends of the cylinder.

Spheres ■ Center Marker - Center marker that defines the center of the ellipsoid.

■ X Scale Factor, Y Scale Factor, Z Scale Factor - Radial dimensions along the center marker’s x-, y-, and z-axes.


To modify: Specify:


Modifying Parts95

Frustums The options for modifying a frustum as explained below. The options are also shown in the Figure 43.

Figure 43. Frustum Options

■ Center Marker - Marker at the center of the bottom of a frustum. Orient the center marker so that its z-axis is normal to the bottom of the frustum and points towards the top of the frustum.

■ Angle Extent - Extended angle measured positive (according to the right-hand rule) about the z-axis of the center marker. The angle starts at the positive x-axis of the center marker and extends the arc of the frustum.

■ Length - Height of the frustum. ADAMS/View uses the length value to specify the z distance between the two circles. A positive value specifies a frustum along the positive z-axis of the center marker.

■ Side Count For Body - Number of flat sides ADAMS/View draws on the side of the frustum. The number of sides you specify affects the calculations ADAMS/View uses to determine a part’s mass and inertia. See Modifying Mass and Inertia for Rigid Bodies on page 108.


To modify: Specify:

z

y

x

Radius

θ

Length

Top

BottomRadius

θ = Angle of Extent


Modifying Parts96

Frustums (continued)

■ Top Radius - Radius at the top of a frustum. The top is perpendicular to the center marker z-axis.

■ Bottom Radius - Radius at the bottom of the frustum. The bottom is perpendicular to the center marker z-axis, and the center of the bottom is at the center marker origin.

■ Segment Count For Ends - Number of segments ADAMS/View uses to draw the circles at the ends of the frustum.

Torus ■ Center Marker - Marker at the center of the torus.

■ Angle Extent - Extended angle measured positive (according to the right-hand rule) about the z-axis of the center marker. The angle starts at the positive x-axis of the center marker and subtends the arc of the torus.

■ Major Radius - Radius of the circular spine of the torus.

■ Minor Radius - Radius of the circular cross-sections of the torus.

■ Side Count for Perimeter - Number of circular cross-section to create along the spine of the torus. The number of sides you specify affects the calculations ADAMS/View uses to determine a part’s mass and inertia. See Modifying Mass and Inertia for Rigid Bodies on page 108.

■ Segment Count - Number of sides for each of the circular cross-sections of the torus.


To modify: Specify:


Modifying Parts97

Links The options for modifying a link as explained below. The options are also shown in the Figure 44.

Figure 44. Link Options

■ I Marker - Marker at one end of the link. ADAMS/View calculates the length of the link as the distance between the I marker and the J marker.

■ J Marker - The J marker must lie along the I marker’s x-axis.

■ Width - Width of the link. The width of the link also controls the radius of the semicircular ends (the radius is equal to one half of the link’s width).

■ Depth - Depth of the link.


To modify: Specify:

WidthDepth

I marker J marker


Modifying Parts98

Plates The following options for a plate. Refer to Figure 14 on page 41 for an illustration of the width and radius options for a plate.

■ Marker Name - The markers used to define the vertices of the plate. The first marker listed is the anchor point for the plate. It is the first point that you specified when you created the plate.

■ Width - Thickness of the plate measured along the z-axis of the corner marker.

■ Radius - Radius of the corners of the plate.

Note: To change the corner locations of a plate, modify the markers that define the corner locations.

Extrusions ■ Reference Marker - Marker used to locate and orient the extrusion.

■ Relative To - The coordinate system in which the location and orientation coordinates are specified. If you do not specify this parameter, ADAMS/View uses the default coordinate system.

■ Profile Points or Profile Curve - Enter either:

■ Profile Points - Locations of the points that define the profile. The points are relative to the reference marker.

To edit the locations of the points, select the More button to display the Location Table. For more information on using Location Table, see Editing Locations Using the Location Table on page 102.

■ Profile Curve - Object used to define the profile of the extrusion. You can specify an arc, circle, spline curve, polyline, chain, or outline as the profile curve. The object should be in the xy plane of the reference marker.


To modify: Specify:


Modifying Parts99

Extrusions (continued)

■ Path Points, Path Curve, or Length along Z - Enter either:

■ Path Points - Points used to define the path of the extrusion. The points are relative to the reference marker. The points defines the path along which the profile curve will be extended.

To edit the locations of the points, select the More button to display the Location Table. For more information on using the Location Table, see Editing Locations Using the Location Table on page 102.

■ Path Curve - Object used to define the path of the extrusion. You can specify an arc, circle, spline curve, polyline, chain, or outline. The object defines the path along which the profile curve is extended.

■ Length along Z - Z-axis of the reference marker defining the straight line along which the profile curve will be extruded. Enter a positive length to extrude along the +z-axis.


To modify: Specify:


Modifying Parts100

Revolutions ■ Reference Marker - Marker used to locate and orient a revolution.

■ Relative To - The coordinate system in which the location and orientation coordinates are specified. If you do not specify this parameter, ADAMS/View uses the default coordinate system.

■ Angle Extent - Extended angle measured positive (according to the right-hand rule) about the z-axis of the reference marker. The angle starts at the x-axis of the reference marker and extends the arc of the revolution.

■ Number of Sides - Number of flat sides ADAMS/View draws on a revolution. The number of sides you specify affects the calculations ADAMS/View uses to determine a part’s mass and inertia. See Modifying Mass and Inertia for Rigid Bodies on page 108.

■ Profile Points or Profile Curve - Enter either:

■ Profile Points - Points used to define the profile of the revolution. The points are relative to the revolution’s reference marker. The profile defined by the points is swept around the reference marker’s z-axis.

To edit the locations of the points, select the More button to display the Location Table. For more information on using Location Table, see Editing Locations Using the Location Table on page 102.

■ Profile Curve - Object used to define the profile of the revolution. You can specify an arc, circle, spline curve, polyline, chain, or outline.


To modify: Specify:


Modifying Parts101

Table 7. Elements You Can Modify for Features

To modify: Specify:

Holes and Bosses

■ Center - Location of the center of the hole or boss.

■ Radius - Radius of the hole or boss.

■ Depth - Depth of the hole or boss.

Hollows and Shells

■ Thickness - Depth of the remaining shell after you hollow the object.

Chamfers and Fillets

■ Radius1 - Width of the chamfer bevel or radius of the fillet.

■ Radius2 - Ending radius of the fillet. You specify the end radius if you are creating a variable blend fillet. For more information, see Chamfering and Filleting Objects on page 57.


Modifying Parts102

Editing Locations Using the Location Table

To specify the location of points in lines, polylines, splines, extrusions, and revolutions, you can use the Location Table. The Location Table lets you view the points in the geometry and edit them. You can also save the location information to a file or read in location information from a file. The Location Table is shown below.

Figure 45. Location Table

The next sections explain more about using the Location Table:

■ Displaying the Location Table, 103

■ Entering Text in Cells, 103

■ Resizing Columns, 103

■ Working with Rows, 104

■ Reading and Writing Location Information, 105

■ Resetting Values, 105

For general information on using tables in ADAMS/View, see Using Tables to Enter Values on page 77 in the guide, Learning ADAMS/View Basics.


Modifying Parts103

Displaying the Location Table

To display the Location Table:

■ From a polyline, extrusion, spline, or revolution modify dialog box, select

the More button .

Entering Text in Cells

To enter values in a cell:

1 Click the cell.

The text cursor appears in the cell.

2 Type the values in the selected cell.

To insert text into multiple cells:

1 In the Set Selected text box, enter the text that you want to insert.

2 Select the cells in which you want to insert the text.

3 Select Set Selected.

Resizing Columns

You can change the size of columns displayed in the Location table. You can also resize all columns equally.

To resize a column:

1 Point to the right border of the column heading that you want to resize. The cursor changes to a double-sided arrow.

2 Drag the cursor until the column is the desired size.

3 Release the mouse button.

To resize all columns equally in the Location table:

■ Select either the Widen or Narrow tool .


Modifying Parts104

Working with Rows

In the Location Table, you can add and delete rows.

To insert a row before a row:

1 Select the row above which you want to insert a new row.

2 Select Insert.

To insert a row after a row:

1 Select the row below which you want to insert a new row.

2 Select Append.

To delete a row:

1 Select the row or rows you want to delete.

2 Select Delete.


Modifying Parts105

Reading and Writing Location Information

You can save the current location information in the Location Table in ASCII format. ADAMS/View places spaces between each cell.

You can also read in location information from an ASCII file to be used as the location of points in the associated geometry. The information must be in the same format as numeric data that you input into ADAMS/View using the Import command. For more information, see Importing Test Data on page 40 in the guide, Exchanging Data in ADAMS.

Note that ADAMS/View reads the location information starting at the first line that has numerical information. If there are headers in the file, ADAMS/View reads the header information when you first read in the file and changes the headers in the Location Table accordingly. It resets the headers to the default headers (X, Y, and Z), however, the next time you open the Location Table.

To read or write in location information:

1 Select Write or Read from the Location Table.

The File Selection dialog box appears.

2 Double-click the directory that contains the file.

3 In the File Name text box, type the file name you want to open, or highlight the file in the list.

4 Select OK.

Resetting Values

If you have made changes to values in a table that you would like to clear out and reset to the current values of the object, you can reset the table.

To reset the Location Table:

■ Select Reset.


Modifying Parts106

Modifying Part PropertiesEach moving part in ADAMS/View can have the following properties in addition to having geometry:

■ Mass and inertia

■ Initial velocities

■ Initial location and orientation

ADAMS/View automatically calculates the total mass of the part and its inertia based on the part’ s volume and density. It also automatically calculates the initial velocity and position for the part based on any other initial conditions and connections in your model. You can set how you want ADAMS/View to calculate these properties as well as define these properties yourself as explained in the next sections.

■ About the Part Modify Dialog Boxes, 106

■ Modifying Mass and Inertia for Rigid Bodies, 108

■ Modifying Initial Velocities, 113

■ Modifying Initial Location and Orientation, 116

Note: You can also modify part properties using the Table Editor. For information on using the Table Editor, see Editing Objects Using the Table Editor on page 401.

About the Part Modify Dialog Boxes

To change the part properties for a rigid body or point mass, you use the Modify Rigid Body dialog box or the Modify Point Mass dialog box, respectively. The part modify dialog boxes are shown in Figures 46 and 47.

Follow the instructions in Accessing Modify Dialog Boxes on page 420 to display the appropriate modify dialog box and follow the instructions in the next sections to modify part properties using the dialog box.


Modifying Parts107

Figure 46. Modify Rigid Body Dialog Box

Figure 47. Point Mass Dialog Box

Sets mass properties

Set velocitySet position initial conditions initial conditions

Set velocity initial conditions

Set position initial conditions


Modifying Parts108

Modifying Mass and Inertia for Rigid Bodies

By default, ADAMS/View calculates the mass and inertia for a part based on the part’s geometry and material type. The geometry defines the volume and the material type defines the density. The default material type for rigid bodies is steel.

You can change the material type used to calculate mass and inertia or simply specify the density of the part. If you do not want ADAMS/View to calculate mass and inertia using a part’s geometry, material type, or density, you can enter your own mass and moments of inertia. (For information on creating a material type, see Setting Up Materials on page 118.)

It is possible to assign zero mass to a part whose six degrees of motion you constrain with respect to parts that do have mass. You should not assign a part zero mass, however. Any part that has zero mass and translation degrees of freedom can causes simulation failure (since a = F/m). Therefore, we recommend that you assign finite masses and inertias to all parts. In addition, a part without mass cannot have mass moments of inertia.

The next sections explain how to modify mass and inertia:

■ Modifying Mass and Inertia, 110

■ About Entering Mass Moments of Inertia, 112

■ Displaying Calculated Mass Moments of Inertia, 113


Modifying Parts109

Note: ADAMS/View uses two different methods to calculate mass properties. If you modify the number of sides ADAMS/View uses to define a part’s geometry, such as cylinder, frustum, or torus, ADAMS/View may use a different method to calculate the part’s mass properties depending on the number of sides as explained below.

■ If the number of sides is greater than or equal to the default number of sides (usually 20), ADAMS/View calculates the mass using an analytical equation for the geometry volume. It uses a true solid that the name of the part indicates.

■ If the number of sides is less than the default, ADAMS/View uses a prismatic solid, which you actually see on the screen and uses it to calculate mass properties. This method is slower but gives more accurate results. For example, if you change the number of side of a cylinder from 20 to 3, the geometry on the screen is of a triangular solid. This solid’s mass properties will be significantly different that a cylinder’s mass properties.


Modifying Parts110

Modifying Mass and Inertia

To modify mass and inertia:

1 If you haven’ t already done so, display the Modify Rigid Body dialog box as explained in Accessing Modify Dialog Boxes on page 420.

2 From the option menu, select how you want ADAMS/View to calculate mass and inertia, enter the appropriate values, and select OK. Refer to Table 8 for assistance.

Table 8. Options for Mass and Inertia Properties

From the option menu, select: And enter:

Geometry and Material Type

In the Material Type text box, the type of material for the part. ADAMS/View displays the material’s composition below the text box. ADAMS/View uses the density associated with the material type and volume of the geometry of the part to calculate the part’s mass and inertia.

To select a material type from the Database Navigator or create a new material type, right-click the text box, and then select the appropriate command. For more information on material types, see Setting Up Materials on page 118.

Geometry and Density

In the Density text box, the density of the part. ADAMS/View uses the part’s density and the volume of the geometry to calculate its mass and inertia.


Modifying Parts111

User Input ■ Mass - In the Mass text box, enter the mass of the part.

■ Moments of inertia - Enter the mass moments of inertia. See About Entering Mass Moments of Inertia on page 112 for more information.

■ Center-of-mass marker - In the Center of Mass Marker text box, enter the marker that is to be used to define the center-of-mass (CM) for the part.

■ Inertia marker - In the Inertia Reference Marker text box, specify the marker that defines the axes for the inertia properties. If you do not enter an inertia marker, ADAMS/View uses the part CM marker for inertia properties.

Table 8. Options for Mass and Inertia Properties (continued)

From the option menu, select: And enter:


Modifying Parts112

About Entering Mass Moments of Inertia

ADAMS/View automatically calculates the inertia of a part based on the part’s volume and density. In the Rigid Body Modify dialog box, you can also specify the mass-inertia tensor matrix by selecting User Input from the Mass & Inertia defined by option menu.

The inertia matrix is defined as follows:

The inertia matrix is a symmetrical, positive-definite matrix. You compute the individual terms in the matrix as follows:

■ Ixx = ∫ (y**2 + z**2) dm

■ Iyy = ∫ (x**2 + z**2) dm

■ Izz = ∫ (x**2 + y**2) dm

■ Ixy = ∫ xy dm

■ Ixz = ∫ xz dm

■ Iyz = ∫ yz dm

In the above formula, x, y, and z are the components of the displacement of an infinitesimal mass particle of mass dm, measured from the origin of the inertia marker in the coordinate system of the inertia marker. The integral is performed over the entire mass of the body. If you do not specify the inertia marker, ADAMS/View uses the CM marker. In that case, you compute these quantities about the origin of the CM marker in the coordinate system of the CM marker.

Note: ADAMS/View defines Ixy, Ixz, and Iyz as positive integrals, as shown. Some references define these terms as the negative of these integrals. You should be sure to compute these values as shown above.

In the Rigid Body Modify dialog box, you can enter either just the principal mass moments of inertia (Ixx, Iyy, Izz) or enter the cross products of inertia (Ixy, Ixz, and Iyz). You will want to enter the mass products of inertia if the inertia marker or CM marker

Ixx Ixy IxzIxy Iyy IyzIxz Iyz Izz


Modifying Parts113

is not at the center of mass of the part and not aligned with the principal axes. To enter cross products of inertia, clear the check box Off-Diagonal Terms. The Modify Rigid Body dialog box displays text boxes for entering the cross products of inertia.

Displaying Calculated Mass Moments of Inertia

If you select to have ADAMS/View calculate the mass moments of inertia of a part based on the part’s geometry and material type or density, you can view the mass-inertia tensor matrix that ADAMS/View calculates.

To view the matrix:

■ In the Modify Rigid Body dialog box, select Show calculated inertia.

Modifying Initial Velocities

You can specify initial velocities for rigid bodies and point masses. ADAMS/View uses the initial velocity during the assemble model operation, which it runs before it runs a simulation of your model.

You can specify translational and angular velocities for rigid bodies and only translational velocity for point masses.

■ Translational velocity defines the time rate of change of a part’ s center of mass with respect to ground or another marker in your model. You can specify translational velocity for each vector component of the marker.

■ Angular velocity defines the time rate of change of a part’s rotational position with respect to the CM marker of the part or another marker in your model. You can specify angular velocity for each vector component of the marker.

If you specify initial velocities, ADAMS/View uses them as the initial velocity of the part during assemble model operations regardless of any other forces acting on the part. You can also leave some or all of the velocities unset. Leaving a velocity unset lets ADAMS/View calculate the velocity of the part during an assemble operation depending on the other forces and constraints acting on the part. Note that it is not the same as setting the initial velocity to zero. Setting an initial velocity to zero means that the part will not be moving in the specified direction when the simulation starts regardless of any forces and constraints acting upon it.


Modifying Parts114

To modify initial velocities:

1 If the Display the Modify Rigid Body or Modify Point Mass dialog box is not already displayed, display it as explained in Accessing Modify Dialog Boxes on page 420.

2 Select Velocity ICs.

The Settings dialog box appears with its option menu set to Velocity ICs. If you selected Velocity ICs from the Modify Point Mass dialog box, the Settings dialog box only displays options for setting translational velocity. The Settings dialog box is shown below for rigid bodies.

Set angular

Set translationalvelocity

velocity


Modifying Parts115

3 Set the translational and angular velocity as explained in Table 9 and select Apply.

Table 9. Options for Translational and Angular Velocity

To: Do the following:

Select the coordinate system along or about whose axes the translational or angular velocity vector components will be specified.

Select the following:

■ For translational velocity, select Ground or select Marker and enter a marker in your model in the text box that appears.

■ For angular velocity, select Part CM to select the part’s center-of-mass (CM) marker or select Marker and enter a marker in your model.

To search for or select a marker from the screen, right-click the text box that appears when you select Marker, and then select the appropriate command.

Set the velocity along or about an axis

Select the axes along or about which you want to define velocity and enter the velocity in the text box that appears next to the axes check boxes. Remember, leaving a velocity unset lets ADAMS/View calculate the velocity of the part during an assemble model operation depending on the other forces and constraints acting on the part. It is not the same as setting the initial velocity to zero.


Modifying Parts116

Modifying Initial Location and Orientation

In addition to specifying initial velocities, you can also control the initial position for a part’ s location and orientation. You should specify the initial position when you do not want ADAMS/View to reposition the part. ADAMS/Solver uses the initial position during an assemble model operation, which it runs before it runs a simulation of your model.

You can control initial locations and orientations for rigid bodies and only initial locations for point masses.

■ Location fixes any of the current translational coordinates (x, y, or z) of the part as the initial location.

■ Orientation fixes any of the current body-fixed 313 rotational coordinates (psi, theta, or phi angles) as the initial orientation. These rotation angles are those associated with a body-fixed 313 rotation sequence regardless of which sequence you set as the default for the modeling database. (For more on setting default rotation methods, see About Orientation Angles and Rotations on page 34 of the guide, Learning ADAMS/View Basics.)

If ADAMS/Solver has to alter part positions to obtain consistent initial conditions during an assemble model operation, it does not vary the coordinates you specify unless it must vary them to satisfy the initial conditions you specify for a joint or for a motion.

Note: If you fix the initial positions of too many parts, the assemble model operation can fail. Use initial positions sparingly.


Modifying Parts117

To modify initial position and orientation:

1 Display the Modify Rigid Body or Modify Point Mass dialog box as explained in Accessing Modify Dialog Boxes on page 420.

2 Select Position ICs.

The Settings dialog box appears with its option menu set to Position ICs. If you selected Position ICs from the Modify Point Mass dialog box, the Settings dialog box only displays options for setting location conditions. The Settings dialog box is shown below for rigid bodies.

3 Select the coordinates or angles that you want fixed during assemble model operation and select Apply.

Control initial

Control initial

orientation

locationcoordinates

coordinates


Modifying Parts118

Setting Up MaterialsParts have material properties, defined by their composition, such as restitution coefficient, Young's modulus, Poisson’s ratio, and mass density. Part material properties are important in determining the mass moments of inertia of a part. You can select or modify a part material from the ADAMS/View’s library of materials or you can set up your own material type.

Table 10 shows the material properties for the standard material types in ADAMS/View. All material types in ADAMS/View are assumed to be linearly elastic. ADAMS/View automatically calculates the material’ s Shear Modulus (G) from the Young’s Modulus (E) and Poisson’ s Ratio (ν) according to the equation:

Table 10. Standard Material Types in ADAMS/View

The material:Young’s Modulus value(Newton/meter2):

Poisson’s Ratio: Density (kg/meter3):

Aluminum 7.1705E+ 10 0.33 2740.0

Cast iron 1.0E+11 0.211 7080.0

Steel 2.07E+11 0.29 7801.0

Stainless steel 1.9E+11 0.305 7750.0

Magnesium 4.48E+10 0.35 1795.0

Nickel 2.07E+11 0.291 7750.0

Glass 4.62E+10 0.245 2595.0

Brass 1.06E+11 0.324 8545.0

Copper 1.19E+11 0.326 8906.0

Lead 3.65E+10 0.425 11370

GE

2 1 υ+( )---------------------=


Modifying Parts119

To create or modify a material type:

1 From the Build menu, point to Materials, and then select either New or Modify.

2 If you selected Modify, the Database Navigator appears. Select a material type to modify and select OK. For more information on the Database Navigator, see Navigating Through a Modeling Database on page 147 of the guide, Learning ADAMS/View Basics.

The Create or Modify Material dialog box appears.

3 Change the default name assigned to the new material type, if desired.

4 Enter the values for Young’ s Modulus, Poisson’s Ratio, and mass density.

5 Select the Comments tool on the dialog box and enter any comments you want associated with the material type. For more information on entering comments, see Adding Comments to Objects on page 183 of the guide, Learning ADAMS/View Basics.

6 Select OK.

Titanium 1.0204E+11 0.3 4850.0

Tungsten 3.447E+11 0.28 19222

Wood 1.1E+10 0.33 438.0

Table 10. Standard Material Types in ADAMS/View (continued)

The material:Young’s Modulus value(Newton/meter2):

Poisson’s Ratio: Density (kg/meter3):


Modifying Parts120

Calculating Aggregate Mass of PartsYou can have ADAMS/View calculate the total mass and inertia of a part or parts in your model. ADAMS/View returns the information in the information window or in a specified file. It ignores the ground part or any part that has no mass.

By default, ADAMS/View calculates all location coordinates and orientation angles in the current global coordinate system. You can select a different coordinate system or reference frame relative to which you would like the coordinates and angles returned.

To calculate aggregate mass:

1 From the Tools menu, select Aggregate Mass.

The Aggregate Mass dialog box appears.

2 From the option menu, select one of the following:

■ All Bodies in current model to calculate the aggregate mass of all bodies in your model.

■ Specified Bodies in current model to select only certain parts.

3 If you selected to calculate the aggregate mass of only a selected set of parts, select Select. A list of parts in your model appears. Select the desired parts.

■ To select a single part, click the part.

■ To use the mouse to select a continuous set of parts, drag the mouse over the parts that you want to select or click on one part, hold down the Shift key, and click the last part in the set. All part between the two selected parts are highlighted.

■ To use the up and down arrow keys to select a continuous set of parts, click on the first part, hold down the Shift key, and then use the up or down arrow to select a block of parts.

■ To select a noncontinuous set of parts, click on a part, hold down the Ctrl key, and click on the individual parts that you want.

■ To clear any part in the selected list, hold down the Ctrl key and then click the selected part to clear its selection.


Modifying Parts121

4 In the Relative to text box, if desired, enter another coordinate system, with respect to which you’d like calculations to be relative. By default the calculations are relative to the global coordinate system.

5 Select how you want the output displayed. You can display it in the information window and to a file. (Note that currently, Brief Output has no impact on the type of information displayed.)

If you want to save the results to a file, in the File Name text box, enter the name of the file in which you want to save the information. If you want the information written to a directory other than the one from which you are running ADAMS/View, enter the path.

6 Select OK.


Modifying Parts122

Measuring Distances Between MarkersYou can quickly have ADAMS/View calculate the relative distance and orientation between two coordinate system markers or a marker and ground. It’s a quick way to check the relationship between two markers without creating a measure or request. You will find it helpful to check if two markers in your model are at the proper distance or orientation.

ADAMS/View calculates the following distance information:

■ Magnitude

■ x, y, and z component

■ Angular displacement

You can also select that ADAMS/View calculate the results relative to a reference marker. When you select a reference marker, ADAMS/View calculates the distance information in the coordinate system of the reference marker. If you do not specify a reference marker, ADAMS/View calculates the distance relative to the ground part.

You can select to measure the distance at the model’s initial configuration (how you built it) or at particular simulation step. You can specify a time, frame number, or a configuration of the model. For the model configuration, you can select:

■ Model input - The model configuration that was input to ADAMS/Solver, the analysis engine, before it ran a simulation.

■ Initial conditions - The model configuration after initial conditions were met.

■ Equilibrium - The configuration after an equilibrium simulation.

■ Forward - One frame forward from the currently displayed frame.

■ Backward - One frame backward from the currently displayed frame.

You can view the results in an information window or have ADAMS/View store the results in a file.


Modifying Parts123

To calculate the distance between markers:

1 From the Tools menu, select Measure Distance.

The Measure Distance dialog box appears.

2 Enter the marker or markers whose distance you want to calculate in the first three text boxes.

■ First Marker Name - Enter the marker from which you want to measure the distance.

■ Second Marker Name - Enter the marker to which you want measure the distance.

■ Ref Marker Name - Enter the marker to be used as the reference marker.

3 Select how you want the distance information displayed. You can select all of the following:

■ On the screen in an information window - Select Display Results.

■ In a file - In the Write Result to File Name text box, enter the name of the file in which you want to save the distance information. If you want the information written to a directory other than the one from which you are running ADAMS/View, include the path.

4 Select either:

■ Model Name if you want to calculate the distance based on the current configuration of a model.

■ Analysis Name if you’d like to calculate the distance based on a configuration, frame, or simulation time from a particular simulation.

The elements in the dialog box change depending on your selection.


Modifying Parts124

5 Enter the options in the dialog box as explained in the table below and select OK. As you set options, remember that you can use the pop-up menu that appears when you hold down the right mouse button in a text box to select an object from the screen or a list

Table 11. Model and Analysis Options

If you selected: Do the following:

Model Name In the Model Name text box, enter the name of the model. If you want to measure distances in the current model, you do not need to enter a model name.

Analysis Name 1 Enter the name of a simulation. 2 Select to use a particular time, frame, or

configuration stored in the selected simulation.

4 About Constraining Your Model

OverviewAfter you’ve created the parts for your model, you need to define how they are attached to one another and how they move relative to each other. You use constraints to specify part attachments and movement. This chapter explains the different types of constraints and how to add them to your model. It contains the following sections:

■ About Constraints, 126

■ Accessing the Constraint Creation Tools, 134

■ Tips on Constraining Your Model, 136


About Constraining Your Model126

About ConstraintsConstraints define how parts (rigid bodies, flexible bodies, and point masses) are attached to one another and how they are allowed to move relative to each other. Constraints restrict relative movement between parts and represent idealized connections. The next sections explain more about constraints.

■ Types of Constraints, 127

■ Constraints and Degrees of Freedom, 128

■ Connecting Constraints to Parts, 132

■ Orienting Constraints, 133

■ Constraint Naming Conventions, 133



Types of Constraints

ADAMS/View provides a library of constraints including:

■ Idealized joints - Have a physical counterpart, such as a revolute (hinge) or translational (sliding dovetail) joint.

■ Joint primitives - Place a restriction on relative motion, such as the restriction that one part must always move parallel to another part.

■ Motions generators - Drive your model.

Figure 48 shows some of the different types of idealized joints that ADAMS/View supports.

Figure 48. Different Types of Constraints

Planar Joint

Convel Joint

Fixed Joint

Cylindrical JointConstant Velocity Cylindrical

Fixed Planar



Constraints and Degrees of Freedom

Degrees of freedom (DOF) are a measure of how parts can move relative to one another in a model. A body free in space has six DOF in which it can move: three translational and three rotational. Each DOF corresponds to at least one equation of motion. When you add a constraint, such as a revolute joint, between two parts, you remove DOF between the parts, causing them to remain positioned with respect to one another regardless of any motion or force in the model. Each constraint in ADAMS/View removes different DOF.

For example, a revolute joint removes all three translational DOF and two of the rotational DOF between two parts. If each part had a point on the joint that was on the centerline of the revolute pin, then the two points would always remain coincident. They would only rotate with respect to one another about one axis: the centerline of the revolute joint.

The total number of DOF in a model is equal to the difference between the number of allowed part motions and the number of active constraints in the model. When you run a simulation of your model, ADAMS/Solver calculates the number of DOF in your model as it determines the algebraic equations of motion to be solved in your model. You can also calculate the DOF in your model before running a simulation as explained in Verifying Your Model on page 92.

For a list of the DOF that the different constraints in ADAMS/View remove, see Tables 12, 13, 14, and 15. The content of each table is explained below.

■ Table 12 lists all of the idealized joints except screw, gear, and coupler joints. It does not contain screw joints because they couple one rotational and one translational DOF and cannot be placed in any one of the categories in the table. The table does not contain gears and couplers because they connect joints rather than parts.

■ Table 13 lists all of the joint primitives. It also shows the DOF that the joint primitives remove when used alone or in combination with other primitives.

■ Table 14 lists the DOF that contacts remove.



■ Table 15 lists motions that can be applied to the axes of parts. It places the general point motion in all fields of the table because a general point motion can apply motion to none, any, or all axes of a part.

Table 12. DOF Removed by Idealized Joints

Rotational DOF Removed

0 1 2 3

Tran

slat

ion

al D

OF

Rem

ove

d 0 (Part)

1 Planar

2 Cylindrical Translational

3 SphericalHooke/UniversalConstant Velocity

Revolute Fixed



Table 13. DOF Removed by Joint Primitives


0 1 2 3

Tran

slat

ion

al D

OF

Rem

ove

d 0 (Part) Perpendicular Parallel Axes Orientation

1In Plane In Plane +

PerpendicularIn Plane + Parallel Axes

In Plane + Orientation

2In Line In Line +

PerpendicularIn Line + Parallel Axes

In Line + Orientation

3 (Spherical) (Spherical) + Perpendicular

(Spherical) + Parallel Axes

(Spherical) + Orientation

Table 14. DOF Removed by Contacts


0 1 2 3

Tran

slat

ion

al D

OF

Rem

ove

d 0 (Part)

1

2 Cams

3



Table 15. DOF Removed by Motions


0 1 2 3

Tran

slat

ion

al D

OF

Rem

ove

d 0 (Part) Point Motion Point Motion Point Motion

1Point Motion Point Motion Point Motion Rotational

Joint Motion

2 Point Motion Point Motion Point Motion Point Motion

3

Point Motion Point Motion Translational Joint Motion

Point Motion



Connecting Constraints to Parts

ADAMS/View uses the convention that the first part that you select when you create a constraint is the part that moves relative to the second part that you select. For example, if you join a door and a door frame with a joint, the first part that you select is the door so that it moves relative to the door frame.

ADAMS/View always applies forces at the location of the constraint. For example, for a revolute joint, ADAMS/View applies any forces at the center of the joint. For joints that allow translational movement, such as a screw joint connecting a nut and bolt, the location of the joint changes over time as the first part moves relative to the second part and, therefore, the locations of the forces change. For the nut and bolt, as the nut moves along the bolt, the location of the joint changes and the reaction forces also change relative to the bolt.

When you create many of the constraints in ADAMS/View, including most idealized joints, primitive joints, and some types of motion, ADAMS/View provides you with shortcuts for specifying the parts that the constraints are to connect or to which the motion is to be applied. As you create a constraint, you can:

■ Let ADAMS/View connect the constraint to the parts nearest to the constraint location. If there is only one part, ADAMS/View assumes the second part is ground. Note that letting ADAMS/View select the parts is only appropriate when two parts are located near one another and when it does not matter which part ADAMS/View considers the first or second part.

There are some constraints, such as revolute, translational, and cylindrical, to which you can apply motions. If you think that you will apply a joint motion, you should explicitly select the two parts when creating the constraints.

There are other constraints, such as Hooke/universal, inline, and perpendicular, which are very sensitive to which part is the first part and which part is the second part. When you create these constraints, you should explicitly select the parts to be connected.

■ Explicitly select the parts to be connected. The first part that you select moves relative to the second part that you select.



■ If you created your model in exploded view, which lets you create individual parts and then assemble them together into a model, you can specify the parts to be connected by the constraint and then select a different location for the constraint on each part. When you assemble the parts into a model, ADAMS/View joins the parts together at the location on the first part that you selected.

When you create a constraint, ADAMS/View creates markers at the specified location on both parts. ADAMS/View orients the markers in the direction of the axis along which the parts can move with respect to each other. The marker on the first part is often called the I marker and the marker on the second part is called the J marker.

Orienting Constraints

You can orient a constraint to the global coordinate system or the working grid if it is turned on. You can also select a direction vector along which you want the constraint oriented.

Constraint Naming Conventions

As you create constraints, ADAMS/View automatically generates names for them based on their type and the number of objects of that type in your model.

■ When you create an idealized joint, ADAMS/View assigns it the name JOINT followed by an underscore (_) and its number (for example, JOINT_1).

■ When you create a joint primitive, ADAMS/View assigns it the name JPRIM followed by an underscore and its number (for example, JPRIM_1).

The numbers are ADAMS IDs used to identify the element in the ADAMS/Solver dataset (.adm) file.

You can rename your constraints as desired. See Renaming Objects on page 425 for more information.



Accessing the Constraint Creation ToolsYou can create constraints using the tools on the Joint palette or the tools on the Joint and Motion tool stacks on the Main toolbox. The palette contains the entire library of constraints while the tool stacks contain only subsets of the most commonly used constraints. The palette and tool stacks for creating constraints are shown below. For more on tool stacks and palettes, see Using Toolboxes and Toolbars on page 47 of the guide, Learning ADAMS/View Basics.

Figure 49. Constraint Palette and Tool Stacks

Joint palette

Joint tool stackon Main toolbox

Settingscontainer

Motion tool stackon Main toolbox



As you create constraints, ADAMS/View provides settings that you can control when specifying the constraints. It provides the settings in a container at the bottom of the palette or Main toolbox. The settings change depending on the type of constraint that you are creating. For example, Figure 49 shows the attachment and alignment values associated with creating a revolute joint that appear in the settings container.

You can use the settings to control how you want ADAMS/View to create the constraints. For example, when you create a rotational motion, ADAMS/View lets you specify its speed before creation. You can also define design variables or expressions for these setting values.

To display the Joint palette:

■ From the Build menu, select Joints.

To display the contents of the Joint or Motion tool stack:

■ From the Main toolbox, right-click the Joint or Motion tool stack.

By default, the Revolute tool appears at the top of the Joint tool stack and

the Rotational Motion tool appears at the top of the Motion tool stack.



Tips on Constraining Your ModelThe following are some tips to help you constrain your model correctly.

■ Build your model by adding constraints to a few parts and testing the constraint connections frequently. By building your model, you can more easily pinpoint the cause of any simulation problems.

■ Be sure that you connect the right parts and that you correctly define which part should move relative to another part.

As explained in Connecting Constraints to Parts on page 132, be sure that you connect the right parts and that you explicitly select which part is to move relative to another part if the constraint allows translational motion.

■ Be sure to orient the constraint correctly.

If you do not define constraint directions correctly, you might not remove DOF from the model that you intended to and, in fact, you might remove DOF that you did not intend to.

For example, if you have a slider-crank model and you direct a translational joint between the slider and ground so that it is out of the plane of desired motion, the model locks up immediately when you run a simulation.

■ Be sure to select the correct type of constraint.

■ Try to find only one constraint that removes all the DOF that you need to remove. If you define more than one constraint between two parts, you get the union of the DOF that each constraint removes, which may not be what you expected.

For example, if you have two concentric, cylindrical parts that you want to allow to rotate and translate with respect to each other, and you use one translational and one revolute joint between the parts, you lock the parts together. They lock together because the translational joint allows no relative rotational movement and the revolute joint allows no relative translational movement. In this case, instead of using the two joints, you should use a single cylindrical joint.

■ Check the DOF in your system periodically.



Use the Verify command to check the DOF in your model to make sure you have the correct number of parts and constraints. For more information on the Verify command, see Verifying Your Model on page 92 of the guide, Simulating Models in ADAMS/View.

■ Run a kinematic simulation to test your model without forces.

If possible, run a kinematic simulation before performing a dynamic simulation. By running a kinematic simulation, you can ensure that connections are correct before you add forces to your model. You may have to add temporary constraints to your model to run a kinematic simulation. For more on performing simulations of your model, see the guide, Simulating Models in ADAMS/View.

■ Remove redundant constraints from your model even if a simulation of your model runs correctly. For more on redundant constraints, see More on Redundant Constraint Checking on page 97 in the guide, Simulating Models in ADAMS/View.



5 Working with Joints

OverviewThis chapter explains how to work with the two types of joints in ADAMS/View:

■ Working with Idealized Joints, 140

■ Working with Joint Primitives, 172


Working with Joints140

Working with Idealized JointsIdealized joints are mathematical representations of joints that have physical counterparts, such as a revolute (hinge) or translational joint (sliding dovetail). ADAMS/View provides a variety of idealized joints from which you can choose. The next sections explain the different types of joints and how to create and modify them.

■ About Idealized Joints, 140

■ Working with Simple Idealized Joints, 141

■ Working with Complex Idealized Joints, 163

About Idealized Joints

Idealized joints connect two parts. The parts can be rigid bodies, flexible bodies, or point masses. You can place idealized joints anywhere in your model.

ADAMS/View supports two types of idealized joints: simple and complex. Simple joints directly connect bodies and include the following:

■ Revolute Joints

■ Translational Joints

■ Cylindrical Joints

■ Spherical Joints

■ Planar Joints

■ Constant-Velocity Joints

■ Screw Joints

■ Fixed Joints

■ Hooke/Universal Joint

Complex joints indirectly connect parts by coupling simple joints. They include:

■ Couplers

■ Couplers

The next sections explain each type of joint.



Working with Simple Idealized Joints

The next sections explain each idealized joint in the ADAMS/View joint library and how to create and modify the joints in ADAMS/View. For a listing of the DOF that the simple idealized joints allow, see Table 12 on page 129.

■ Revolute Joints, 142

■ Translational Joints, 143

■ Cylindrical Joints, 144

■ Spherical Joints, 145

■ Planar Joints, 146

■ Constant-Velocity Joints, 147

■ Screw Joints, 148

■ Fixed Joints, 149

■ Hooke/Universal Joint, 151

■ Creating a Simple Idealized Joint, 153

■ Modifying a Simple Idealized Joint, 155



Revolute Joints

A revolute joint (shown in Figure 50) allows the rotation of one part with respect to another part about a common axis. The revolute joint can be located anywhere along the axis about which the joint’s parts can rotate with respect to each other.

The orientation of the revolute joint defines the direction of the axis about which the joint’s parts can rotate with respect to each other. The rotational axis of the revolute joint is parallel to the orientation vector and passes through the location.

You can also add friction to a revolute joint as explained in Adding Friction to Joints on page 162.

Figure 50. Revolute Joint

First part

Axis ofrotation

Second part

Location



Translational Joints

A translational joint (shown in Figure 51) allows one part to translate along a vector with respect to a another part. The parts can only translate, not rotate, with respect to each other.

When you create a translational joint, you specify its location and orientation. The location of a translational joint does not affect the motion of the joint. It simply determines where ADAMS/View places the joint. The orientation of the translational joint, however, determines the direction of the axis along which the parts can slide with respect to each other. The direction of the motion of the translation joint is parallel to the orientation vector and passes through the location.

You can also add friction to a translational joint as explained in Adding Friction to Joints on page 162.

Figure 51. Translational Joint

Firstpart

Secondpart

Axis oftranslation



Cylindrical Joints

A cylindrical joint (shown in Figure 52) allows both relative rotation as well as relative translation of one part with respect to another part. A cylindrical joint can be located anywhere along the axis about which the parts can rotate or slide with respect to each other.

The orientation of the cylindrical joint defines the direction of the axis about which the parts can rotate or slide along with respect to each other. The rotational axis of the cylindrical joint is parallel to the orientation vector and passes through the location.

You can also add friction to a cylindrical joint as explained in Adding Friction to Joints on page 162.

Figure 52. Cylindrical Joint

Second part

First partAxis oftranslationand rotation



Spherical Joints

A spherical joint (shown in Figure 53) allows the free rotation about a common point of one part with respect to another part. The location of the spherical joint determines the point about which the joint’s parts can pivot freely with respect to each other.

You can also add friction to a spherical joint as explained in Adding Friction to Joints on page 162.

Figure 53. Spherical Joint

Second part

First part

Location



Planar Joints

A planar joint (shown in Figure 54) allows a plane on one part to slide and rotate in the plane of another part. The location of the planar joint determines a point in space through which the joint’s plane of motion passes.

The orientation vector of the planar joint is perpendicular to the joint’s plane of motion. The rotational axis of the planar joint, which is normal to the joint’s plane of motion, is parallel to the orientation vector.

Figure 54. Planar Joint

Normal axis

Location

Second part

First part



Constant-Velocity Joints

A constant-velocity joint (shown in Figure 55) allows two rotations on one part with respect to another part, while remaining coincident and maintaining a constant velocity through the spin axis.

You can also add friction to a constance-velocity joint as explained in Adding Friction to Joints on page 162.

Figure 55. Constant-velocity Joint

Location

θ

θ

Second part axisof rotationFirst part axis

of rotation



Screw Joints

A screw joint specifies the rotation of one part about an axis, as the part translates along the axis with respect to a second part.

The screw joint does not require that the two parts remain parallel with respect to the axis of rotation and translation. However, the z-axis of the coordinate system marker on the first part and the z-axis of the coordinate system marker on the second part must always be parallel and co-directed. Although the screw joint does not enforce this parallelism, the chain of parts and joints that connects the two markers should.

After you create a screw joint, you need to specify the pitch value. The pitch value is the distance from one peak on a thread of the screw to the next thread. It defines the amount of translational displacement of the first part for every rotation of the second part about the axis of rotation. By default, ADAMS/View sets the pitch value to 1. The pitch value is in length units. A positive pitch creates a right-hand thread, and a negative pitch creates a left-hand thread.

Figure 56. Screw Joint

Axis of Translationand Rotation

FirstRigidBody

SecondRigidBody

zi

xj

φ

xi

zj

Axis oftranslationand rotation

Firstpart

Secondpart

Pitch



Fixed Joints

A fixed joint locks two parts together so they cannot move with respect to each other. The effect is similar to defining two parts as a single part. If you want to have the two parts move relative to each other in a future analysis, simply delete the fixed joint and use another type of joint.

Figure 57. Fixed Joint

For a fixed joint, the location and orientation of the joint often do not affect the outcome of the simulation. In these cases, you can place the joint at a location where the graphic icon is easily visible. However, occasionally the placement of the fixed joint can allow force moments to become quite large depending on where you place the joint as shown in Figure 58. In this type of case, be sure to place it where you get the results that you want.

First Rigid Body

Second Rigid Body

Firstpart

Secondpart



Figure 58. Location of Fixed Joint on Beam

Force

Force

Large torque generated here

No or small torque generated at joint



Hooke/Universal Joint

A hooke/universal joint (shown in Figures 59 and 60) allows the rotation of one rigid body to be transferred to the rotation of another rigid body. This joint is particularly useful when transferring rotational motion around corners, when you need to simulate the non-constant velocity of a physical universal joint, or when transferring rotational motion between two connected shafts that are permitted to bend at the connection point (such as the drive shaft on an automobile).

The location point of the universal joint represents the connection point of the two parts. For a hooke joint, two shaft axes leading to the cross bars identify the axes about which the two parts are permitted to rotate with respect to each other. Note that ADAMS/View uses rotational axes that are parallel to the rotational axes you identify but that pass through the location point for the hooke joint. For a universal joint, the cross bars identify the axes about which the two parts are permitted to rotate with respect to each other.

You can also add friction to a hooke/universal joint as explained in Adding Friction to Joints on page 162.



Figure 59. Hooke Joint

Figure 60. Universal Joint

Firstpart

Location

Secondpart

First axis

Second axis

First

Location

Secondpart

First axis

part

Second axis



Creating a Simple Idealized Joint

The following procedure explains how to create a simple joint. Note that this procedure only sets the location and orientation of the joint. If you want to set the friction of a joint, change the pitch of a screw joint, or set initial conditions for joints, modify the joint as explained in Modifying a Simple Idealized Joint on page 155.

To create a simple idealized joint:

1 From the Joint tool stack or palette, select the joint tool representing the idealized joint that you want to create.


■ How you want the joint connected to parts. You can select the following:

■ 1 location (Bodies Implicit) - Lets you select the location of the joint and have ADAMS/View determine the two parts that should be connected. ADAMS/View selects the parts closest to the joint location. If there is only one part near the joint, ADAMS/View connects the joint to that part and ground.

■ 2 Bodies - 1 Location - Lets you explicitly select the two parts to be connected by the joint and the location of the joint. The joint remains fixed on the first part and moves relative to the second part.

■ 2 Bodies - 2 Locations - Lets you explicitly select the two parts to be connected by the joint and the location of the joint on each part. You should use this option if you are working in exploded view. For more on exploded view, see Assembling Your Model on page 102 of the guide, Simulating Models in ADAMS/View.

For more on the effects of these options, see Connecting Constraints to Parts on page 132.

■ How you want the joint oriented. You can select:

■ Normal to Grid - Lets you orient the joint along the current working grid, if it is displayed, or normal to the screen.

■ Pick Feature - Lets you orient the joint along a direction vector on a feature in your model, such as the face of a part.



3 Select the first part to be connected using the left mouse button. If you selected to explicitly select the parts to be connected, select the second part in your model using the left mouse button.

4 Place the cursor where you want the joint to be located, and click the left mouse button. If you selected to specify its location on each part, place the cursor on the second location, and click the left mouse button.

5 If you selected to orient the joint along a direction vector on a feature, move the cursor around in your model to display an arrow representing the direction along a feature where you want the joint oriented. When the direction vector represents the correct orientation, click the left mouse button.



Modifying a Simple Idealized Joint

You can change several properties about a simple idealized joint after you create it. The properties include:

■ Basic properties, such as the parts that the joint connects and the joint’s type.

■ Initial conditions, such as a joint’s translational displacement and velocity. Initial conditions apply to only certain types of simple idealized joints.

■ Point motion that is applied to the joint.

■ Friction that is applied to joints.

The next sections explain how to modify a simple idealized joint.

■ About the Modify Joint Dialog Box, 156

■ Modifying Basic Properties, 157

■ Setting Initial Conditions, 159

■ Imposing Point Motion on a Joint, 161

■ Adding Friction to Joints, 162

Note: You can also modify joint properties using the Table Editor. For more information on editing objects using the Table Editor, see Editing Objects Using the Table Editor on page 401.



About the Modify Joint Dialog Box

To change the properties for a simple idealized joint, you use the Modify Joint dialog box shown in Figure 61.

Follow the instructions in Accessing Modify Dialog Boxes on page 420 to display the Modify Joint dialog box and follow the instructions in the next sections to modify joint properties using the dialog box.

Figure 61. Modify Joint Dialog Box

Set basic properties

Set initial

Apply motion

Apply friction

conditions

to joint



Modifying Basic Properties

You can change several basic properties about a joint. These include:

■ Parts that the joint connects. You can also switch which part moves relative to another part.

■ What type of joint it is. For example, you can change a revolute joint to a translational joint. The following are exceptions to changing a joint’ s type:

■ You can only change a simple idealized joint to another type of simple idealized joint or to a joint primitive.

■ You cannot change a joint’s type if motion is applied to the joint. In addition, if a joint has friction and you change the joint type, ADAMS/View removes the friction.

■ You cannot change a screw joint’s type nor can you change another joint to a screw joint.

■ Whether or not forces that are applied to the parts connected by the joint appear graphically on the screen during an animation. You can select to display force graphics for either part that the joint connects. Force graphics display an arrow in the direction of the force. The length of the arrow is proportional to the magnitude of the force. By default, ADAMS/View turns off all force graphics for joints. For information on setting preferences for force graphics, see Setting Up Force Graphics on page 201 of the guide, Simulating Models in ADAMS/View.

■ For a screw joint, you can also set the pitch of the threads of the screw. For more on the pitch value, see Screw Joints on page 148.



To change basic properties for a joint:

1 If you haven’ t already done so, display the Modify Joint dialog box as explained in Accessing Modify Dialog Boxes on page 420.

2 If desired, in the First Body and Second Body text boxes, change the parts that the joint connects. The part that you enter as the first body moves relative to the part you enter as the second body.

3 From the Type option menu, select the type of joint to which you want to change the current joint.

4 Select whether you want to display force graphics for one of the parts that the joint connects.

5 For a screw joint, enter its pitch value.

6 Select OK, or select Apply to apply the changes but keep the dialog box displayed so that you can change other joint properties as explained in the next sections.



Setting Initial Conditions

You can specify initial conditions for revolute, translational, and cylindrical joints. ADAMS/View uses the initial conditions during an assemble model operation, which it runs before it runs a simulation of your model.

You can specify the following initial conditions for revolute, translational, and cylindrical joints:

■ Translational or rotational displacements that define the translation of the location of the joint on the first part (I marker) with respect to its location on the second part (J marker) in units of length. You can set translational displacement on a translational and cylindrical joint and you can set rotational displacements on a revolute and cylindrical joint.

ADAMS/View measures the translational displacement at the origin of the I marker along the common z-axis of the I and J markers and with respect to the J marker. It measures the rotational displacement of the x-axis of the I marker about the common z-axis of the I and J markers with respect to the x-axis of the J marker.

■ Translational or rotational velocity that define the velocity of the location of the joint on the first part (I marker) with respect to its location on the second part (J marker) in units of length per unit of time.

ADAMS/View measures the translational velocity of the I marker along the common z-axis of I and J and with respect to the J marker. It measures the rotational velocity of the x-axis of the I marker about the common z-axis of the I and J markers with respect to the x-axis of the J marker.

If you specify initial conditions, ADAMS/View uses them as the initial velocity of the joint during an assemble model operation regardless of any other forces acting on the joint. You can also leave some or all of the initial conditions unset. Leaving an initial condition unset lets ADAMS/View calculate the conditions of the part during an assemble model operation depending on the other forces acting on the joint. Note that it is not the same as setting an initial condition to zero. Setting an initial condition to zero means that the joint will not be moving in the specified direction or will not be displaced when the model is assembled, regardless of any forces acting on it.



If you impose initial conditions on the joint that are inconsistent with those on a part that the joint connects, the initial conditions on the joint have precedence over those on the part. If, however, you impose initial conditions on the joint that are inconsistent with imparted motions on the joint, the initial conditions as specified by the motion generator take precedence over those on the joint.

To modify initial conditions:

1 If it is not already displayed, display the Modify Joint dialog box as explained in Accessing Modify Dialog Boxes on page 420.

2 Select Initial Conditions.

The Joint Initial Conditions dialog box appears. Some options in the Joint Initial Conditions dialog box are not available (ghosted) depending on the type of joint for which you are setting initial conditions.

3 Set the translational or rotational displacement or velocity and select OK.

Tip: If the initial rotational displacement of a revolute or cylindrical joint varies by anywhere from 5 to 60 degrees from the actual location of the joint, ADAMS/View issues a warning message and continues execution. If the variation is greater than 60 degrees, ADAMS/View issues an error message and stops execution.



Imposing Point Motion on a Joint

You can impose a motion on any of the axes (DOF) of the joint that are free to move. For example, for a translational joint, you can apply translational motion along the z-axis. For more on point motions, see Imposing Point Motion on page 186.

Note: For translational, revolute, and cylindrical joints, you might find it easier to use the joint motion tools to impose motion. For more information, see Imposing Joint Motion on page 181.

To impose motion on a joint:

1 If the Modify Joint dialog box is not already displayed, display it as explained in Accessing Modify Dialog Boxes on page 420.

2 Select Impose Motion.

The Impose Motion dialog box appears. Some options in the Impose Motion dialog box are not available (ghosted) depending on the type of joint on which you are imposing motion.

3 Enter a name for the motion. ADAMS/View assigns a default name to the motion.

4 Enter the values for the motion as explained in Table 18 on page 193, and select OK.



Adding Friction to Joints

You can model both static (Coulomb) and dynamic (viscous) friction in revolute, translational, cylindrical, hooke/universal, and spherical joints.

To add friction to a joint:

1 If the Modify Joint dialog box is not already displayed, display it as explained in Accessing Modify Dialog Boxes on page 420.

2 From the Modify Joint dialog box, select the Friction tool .

The Joint Friction dialog box appears. The options in the dialog box change depending on the type of joint for which you are adding friction.

3 Enter the values in the dialog box and select OK. For more information on the values to be entered in the dialog box, see the FRICTION statement in the guide, Using ADAMS/Solver.



Working with Complex Idealized Joints

A complex idealized joint is a joint that connects parts indirectly by connecting simple idealized joints. ADAMS/View provides you with two types of complex idealized joints: gear joints and coupler joints. The following sections explain how to create each type of complex joint:

■ Working with Gears, 163

■ Working with Coupler Joints, 168

Working with Gears

You can use a gear joint to relate the motion of parts and joints. The following sections explain more about gears:

■ About Gears, 163

■ Creating and Modifying a Gear, 166

About Gears

A gear joint (shown in Figure 62) creates a gear pair that relates the motion of three parts and two joints using a coordinate system marker, called the common velocity marker, to determine the point of contact. It connects two of the parts, which are called the geared parts, by coupling together the allowable degrees of freedom in two joints. The coupled joints are attached to the third part, called the carrier part. The joints can be translational, revolute, or cylindrical joints. Using different combinations of joint types and orientations, you can model many different physical gears, including spur, helical, planetary, bevel, and rack-and-pinion.



Figure 62. Gear Joint

When you create the joints to be geared together, you must create them so the first part you select is a geared part and the second part is the carrier part. Therefore, the I marker parameters of the joints must belong to the geared parts and the J marker parameters must belong to the carrier part. In addition, the common velocity marker must belong to the carrier part.

The gear uses the location of the common velocity marker to determine the point of contact or mesh of the two geared parts. The direction of the z-axis of the common velocity marker points in the direction of the common motion of the geared parts. This is also the direction in which the gear teeth forces act.

The location of the common velocity marker is constant with respect to the carrier part. Its location does not change when the direction of power flow through the gear changes.

Carrier partJoint 1

Joint 2

Commonvelocity marker

Part A Part B

■ Joint 1 connects Part A to carrier part

■ Joint 2 connects Part B to carrier part

■ Common velocity marker is fixed in carrier part so its z-axis points along the direction of common movement for the geared parts.

θA

θB

(on carrier)

Z



The algebraic equation that the gear joint adds to your model, in general, looks like the following:

S1q1 + S2q2 = 0

where:

■ q1 and q2 are the rotational or translation displacement variables defined by the allowable DOF in the geared joints.

■ S1 and S2 represent scalar multipliers that act to couple these displacements together. S1 and S2 are defined indirectly by the spatial relationship between the locations of the joints with respect to the common velocity marker.

You do not explicitly define the scalar multipliers (gear ratio) when creating a gear. Instead, ADAMS/View automatically determines the gear ratio as the distance between the origin of the common velocity marker and the origins of the coupled joints. The gear ratio is shown in Figure 63.

Figure 63 also shows a specific case of creating a spur gear. For this gear, the general equation is:

a . θA = b . θB

or, to write it in the general form:

a . θA - b . θB = 0

Note: An ADAMS gear joint does not model backlash.



Figure 63. Spur Gear with Gear Ratio Illustrated

Creating and Modifying a Gear

When you create or modify a gear, you specify or change the two translational, revolute, or cylindrical joints located on the carrier part and the coordinate system marker defining the point of contact between the geared parts.

To create or modify a gear:

1 Do one of the following depending on whether you are creating or modifying a gear:

■ To create a gear, select the Gear tool on the Joint tool stack or palette.

The Constraint Create Complex Joint Gear dialog box appears.

■ To modify a gear, display the Constraint Modify Complex Joint Gear dialog box as explained in Accessing Modify Dialog Boxes on page 420.

Both the gear create and modify dialog boxes contain the same set of options.

2 In the Gear Name text box, enter or change the name for the gear. If you are creating a gear, ADAMS/View assigns a default name to the gear.

Joint,θA

Joint,θBZ

Commonvelocity marker

a bGear ratio = a/b



3 In the Adams Id text box, assign a unique ID number to the gear. The ID is an integer number used to identify the gear in the ADAMS/Solver dataset. You only need to specify an ADAMS ID if you are exporting the model to an ADAMS/Solver dataset, and you want to control the numbering scheme used in the file.

Enter a positive integer for the ID or enter 0 to let ADAMS set the ID for you.

4 In the Comments text box, add or change any comments about the gear to help you manage and identify the gear. You can enter any alphanumeric characters. The comments appear in the information window when you select to display information about the gear, in the ADAMS/View log file, and in a command or dataset file when you export your model to these types of files.

5 In the Joint Name text box, enter or change the two translational, revolute, or cylindrical joints to be geared together. ADAMS/View automatically separates the joint names with a comma (,).

6 In the Common Velocity Marker text box, enter or change the marker defining the point of contact between the geared parts. You need to make sure the z-axis of the common velocity marker points in the direction of motion of the gear teeth that are in contact. In Figure 62 on page 164, the z-axis of the common velocity marker is tangent to the pitch circle of the spur gears.

To create a marker, right-click the Common Velocity Marker text box, and then select Create.

Tip: If you encounter a warning message that the gear has a suspicious configuration, the z-axis of the CV marker is probably oriented incorrectly.

7 Select OK.



Working with Coupler Joints

A coupler joint lets you couple two or three joints together. The following sections explain more about couplers and how to create and modify them.

■ About Coupler Joints, 168

■ Creating a Coupler Joint, 169

■ Modifying a Coupler Joint, 169

About Coupler Joints

A coupler joint (shown in Figure 64) creates a coupler between two or three joints. It relates the translational and/or rotational motion of the joints through a linear scaling of the relative motions or through non-linear relationships that you define by entering parameters to be passed to a user-written subroutine that is linked into ADAMS/View. Couplers are useful if your model uses belts and pulleys or chains and sprockets to transfer motion and energy.

Figure 64. Coupler Joint

Although you can couple only two or three joints, more than one coupler can come from the same joint, as shown in Figure 64.

Joint

Joint

Coupler 2Coupler 1

Joint used intwo couplers



Creating a Coupler Joint

When you create a coupler, you can only create a two-joint coupler. You select the driver joint, the joint to which the second joint is coupled, and the coupled joint, the joint that follows the driver joint. To specify the relationship between the driver and the coupled joint or to create a three-joint coupler, you modify the coupler.

To create a coupler:

1 From the Joint tool stack or palette, select the Coupler tool .

2 Select the driver joint to which the second joint is coupled.

3 Select the coupled joint that follows the driver joint.

Modifying a Coupler Joint

When you modify a joint, you can:

■ Set the number of joints being coupled together.

■ Change the joints being coupled together.

■ Select which joint is the driver joint and which are the coupled joints.

■ Specify the relationship between the joints as linear or nonlinear.

■ If you specify a linear relationship, enter scales for the coupled joints.

■ If you specify a nonlinear relationship, enter the parameters to be passed to a user-written subroutine. For more on user-written subroutines, see the guide, Using ADAMS/Solver Subroutines.

Note: You can also modify coupler properties using the Table Editor. For more information on editing objects using the Table Editor, see Editing Objects Using the Table Editor on page 401.



To modify a coupler joint:

1 Display the Modify Coupler dialog box as explained in Accessing Modify Dialog Boxes on page 420.

The Modify Coupler dialog box appears as shown in Figure 65. The options in the dialog box change depending on whether the coupler joint couples two or three joints and whether or not it is linear or nonlinear. The dialog box shown in Figure 65 shows the options for a linear, three-joint coupler.

Figure 65. Modify Coupler Dialog Box

2 If desired, in the Name text box, change the name of the coupler.

3 Select whether or not you want a three-joint coupler or a two-joint coupler and the relationship between the joints (either linear or nonlinear).

4 If desired, in the Driver and Coupled text boxes, change the joints to be coupled and, from the Freedom Type option menu, select their type.

5 If you have any cylindrical joints, you can specify either translational or rotational displacement. Translational joints always have translational displacements. Revolute joints always have rotational displacements.



6 Do the following depending on the relationship set up for the coupler:

■ If the coupler is linear, enter a scale for the second and third coupled joints. The scales are r2 and r3 in the following equation:

delta1 + r2 * delta2 + r3 * delta3 =0

If the joint displacement is rotational, its corresponding delta in the equation above is in radians.

■ If the coupler is nonlinear, specify the user parameters to be passed to a user-written subroutine. For more on user-written subroutines, see the guide, Using ADAMS/Solver Subroutines.



Working with Joint PrimitivesA joint primitive places a restriction on relative motion, such as restricting one part to always move parallel to another part. The joint primitives do not have physical counterparts as the idealized joints do. You can, however, combine joint primitives to define a complex constraint that cannot be modeled using the idealized joints. In fact, you can use the joint primitives to create any of the idealized joints listed in Working with Idealized Joints on page 140.

Table 16 lists the different types of joint primitives that are available in ADAMS/View. In the figures in the table, a solid circle indicates the first part that the joint connects and a hollow circle indicates the second part that the joint connects. The first part is constrained relative to the second part. For a listing of the DOF that the joint primitives allow, see Table 13 on page 130.

Note that joint primitives are only available from the Joint palette, not the Joint tool stack on the Main toolbox.

After you create a joint primitive as explained in the next procedure, you can modify it. You modify it just as you would modify a simple idealized joint. For more information, see Modifying a Simple Idealized Joint on page 155.



Table 16. Joint Primitives

The primitive: Constrains the following: An example:

Inline One part so that it can only move along a straight line defined on a second part. The location of the inline joint on the first part must remain on the z-axis of the second part.

Inplane One part so that it can only move in a plane of a second part. The origin of the inplane joint on the first part must remain in the xy plane of the second part.

Orientation The coordinate system of one part so that it cannot rotate with respect to a second part. The axes of the coordinate systems must maintain the same orientation. The location of the origins of the coordinate systems does not matter.

Second part

First part

z

Second First partpart

y

x

zy

x

Second part

First part

zy

x



Parallel axes The z-axis of the coordinate system of one part so that it remains parallel to the z-axis of the coordinate system of a second part. The coordinate system of the first part can only rotate about one axis with respect to the coordinate system of the second part.

Perpendicular axes

The coordinate system of one part so that it remains perpendicular to the z-axis of a second part. The coordinate system of the first part can rotate about two axes with respect to the second part.

Table 16. Joint Primitives (continued)

The primitive: Constrains the following: An example:

z

Second part

First zpart

z

z

Second part

First part



To create a joint primitive:

1 From the Joint palette, select the joint primitive tool representing the joint that you want to create.


■ How you want the joint connected to parts. You can select the following:

■ 1 Location - Bodies implicit - Lets you select the location of the joint and have ADAMS/View determine the two parts that should be connected. ADAMS/View selects the parts closest to the joint location. If there is only one part near the joint, ADAMS/View connects the joint to that part and ground.

■ 2 Bodies - 1 Location - Lets you explicitly select the two parts to be connected by the joint and the location of the joint.

■ 2 Bodies - 2 Locations - Lets you explicitly select the two parts to be connected by the joint and the location of the joint on each part. You should use this option if you are working in exploded view. For more on exploded view, see Assembling Your Model on page 102 of the guide, Simulating Models in ADAMS/View.


■ How you want the joint oriented. You can select:

■ Normal to Grid - Lets you orient the joint along the current working grid, if it is displayed, or normal to the screen.

■ Pick Geometry Feature - Lets you orient the joint along a direction vector on a feature in your model, such as the face of a part.

3 If you selected to explicitly select the parts to be connected, select each part in your model using the left mouse button.

4 Place the cursor where you want the joint to be located, and click the left mouse button. If you selected to specify its location on each part, place the cursor on the second location and click the left mouse button.



5 If you selected to orient the joint along a direction vector on a feature, move the cursor around in your model to display an arrow representing the direction along a feature where you want the joint oriented. When the direction vector represents the correct orientation, click the left mouse button.

ADAMS/View creates the joint at the specified location.

6 Applying Motion

OverviewA motion generator dictates the movement of a part as a function of time. It supplies whatever force is required to make the part satisfy the motion. For example, a translational joint motion prescribes that a joint on a part move at 10 mm/second in the z direction. You can apply the motion to either idealized joints or between a pair of parts.

The following sections explain more about motions and how to create and modify them.

■ Types of Motion, 178

■ Defining the Motion Magnitude, 179

■ Tips on Creating Motions, 180

■ Imposing Joint Motion, 181

■ Imposing Point Motion, 186


Applying Motion178

Types of MotionADAMS/View provides you with the following types of motion:

■ Joint Motion - Prescribes translational or rotational motion on a translational, revolute, or cylindrical joint. Each joint motion removes one DOF from your model. Joint motions are very easy to create, but they limit you to motions that are applied to the above listed joints and movements in only one direction or rotation.

■ Point Motion - Prescribes the movement between two parts. When you create a point motion, you specify the direction along which the motion occurs. You can impose a point motion on any type of idealized joint, such as a spherical or cylindrical. For more information on imposing point motion on a joint, see Imposing Point Motion on a Joint on page 161.

Point motions enable you to build complex movements into your model without having to add joints or invisible parts. For example, you can represent the movement along an arc, of a ship in the ocean, or a robot’s arm.

For a listing of the DOF that the motions remove, see Table 15 on page 131.


Applying Motion179

Defining the Motion MagnitudeYou can define motion as acceleration, displacement, or velocity over time. By default, ADAMS/View creates a motion that moves at a constant velocity over time. When you create a motion, you can define its magnitude by entering one of the following:

■ Translational or rotational speed - As you create a motion, you can specify the translational or rotational speed of the motion. By default, you enter the rotational speed in number of degrees per second and the translational speed in length units per time unit (for example, number of inches per second).

When ADAMS/View creates the motion, it uses the value you enter as the motion function. It also converts the rotational motion speed to radians. When you modify the motion, you can change the value or enter a function expression or a user-written subroutine as explained next.

■ Function expression - You can use ADAMS/View function expressions to specify the exact movement applied to a joint as a function of time. For example, using function expressions you can define a motion function that holds the joint in a fixed position, as well as one that moves the joint with the required force to produce a constant velocity.

The function expression for a motion must be a function of time. If you make your function a function of displacements, forces, or any other variables in your model, ADAMS/View issues an error message and stops execution.

To learn more about function expressions, see the guide, Using the ADAMS/View Function Builder.

■ Parameters to be passed to a user-written subroutine - You can create a much more complex motion by creating a MOTSUB user-written subroutine and entering the values to be passed to the subroutine to determine the motion. For more on creating subroutines and passing values to them, see the guide, Using ADAMS/Solver Subroutines.


Applying Motion180

Tips on Creating MotionsThe following are some tips for creating motions:

■ The motions that you assign determine the initial displacements and velocities of your model. For any joint that has a motion applied to it, do not specify initial conditions that act in the same direction as the motion. If you specify initial conditions for both the joint and the motion, ADAMS/Solver, the analysis engine, uses the motion conditions and ignores the initial conditions you specified for the joint.

■ You can define a zero motion with respect to time, which is the same as locking two parts together.

■ If any motion generates nonzero initial part accelerations, ADAMS/Solver may not produce reliable accelerations and velocities for the first two or three internal integration steps of a dynamic simulation. ADAMS/Solver automatically corrects for this so the values it returns at the first output step are accurate. A sensor, however, that depends on the accelerations or reaction forces due to this motion may trip unexpectedly before the first output step even though the solution appears correct when the sensor is removed. If this occurs, you should modify the initial conditions set for the motion so that the initial accelerations are zero.

■ If you defined the motion using velocity and acceleration, you cannot set a dynamic simulation so that it uses the ABAM integrator. For more on controlling your simulation, see Changing Solution Settings for Dynamic Simulations on page 147 in the guide, Simulating Models in ADAMS/View.

■ ADAMS/Solver cannot perform a kinematic simulation on a zero-DOF model containing motions whose function expressions are specified as velocity or acceleration. You’ ll need to perform a dynamic simulation instead.


Applying Motion181

Imposing Joint MotionYou can create two types of joint motion.

■ Translational - For a translational motion, ADAMS/View moves the first part that the joint connects along the z-axis of the second part.

■ Rotational - For a rotational motion, ADAMS/View rotates the first part that the joint connects about the z-axis of a second part. The right-hand rule determines the sign of the motion. The z-axis of the first part must be aligned with the z-axis of the second part at all times. The angle is zero when the x-axis of the first part is also aligned with the x-axis of the second part.

The next sections explain how to create and modify a joint motion.

■ Creating a Joint Motion, 182

■ Modifying a Joint Motion, 183


Applying Motion182

Creating a Joint Motion

When you create a joint motion, ADAMS/View creates a motion at the specified joint. It defines the motion as a constant velocity over time based on a speed value that you can enter. The speed value can be a numerical value, function expression, or user-written subroutine, as explained in Defining the Motion Magnitude on page 179.

To create a joint motion:

1 From the Motion tool stack or the Joint palette, select the joint motion tool representing the motion that you want to create. Select either:

■ to create a translational motion.

■ to create a rotational motion.

2 In the settings container, specify the speed of the motion in displacement units per second. By default, ADAMS/View creates a rotational motion with a speed of 30 degrees per second and a translational motion with a speed of 10 millimeters per second.

To enter a function expression or user-written subroutine, right-click the Speed text box, point to Parameterize, and then select Expression Builder to display the ADAMS/View Function Builder. For information on using the Function Builder, see the guide, Using the ADAMS/View Function Builder.

3 Use the left mouse button to select the joint on the screen to which the motion will be applied


Applying Motion183

Modifying a Joint Motion

You can change several properties about a joint motion after you create it. The properties include:

■ Joint to which the motion is applied.

■ Motion direction, either rotational or translational.

■ Motion definition, including how the motion magnitude is defined (displacement, velocity, or acceleration) and the function that defines its magnitude. You can enter a numerical value, function expression, or user-written subroutine for the magnitude.

■ Initial conditions for displacement and velocity. ADAMS/View uses the initial conditions during an assemble model operation, which it runs before it runs a simulation of your model. You can specify the following initial conditions:

■ Initial displacement that defines the translation of the first part in units of length or angles relative to the second part. You can set initial displacement on any joint motion whose magnitude is defined as velocity or acceleration.

■ Initial velocity that defines the velocity of the first part with respect to the second part in units of length or angles per unit of time. You can set initial velocity on any joint motion whose magnitude is defined as acceleration.

Note: You can also modify joint properties using the Table Editor. For more information on editing objects using the Table Editor, see Editing Objects Using the Table Editor on page 401.


Applying Motion184

To modify a joint motion:

1 Display the Impose Joint Motion dialog box as explained in Accessing Modify Dialog Boxes on page 420.

The Impose Joint Motion dialog box appears. The text boxes in the dialog box change depending on the type of motion you are modifying. The following shows the Impose Joint Motion when you are modifying a motion defined by its velocity.

2 Enter the values in the dialog box as explained in Table 17, and then select OK.

Table 17. Options for Impose Joint Motion Dialog Box


Change the joint to which the motion is applied

In the Joint text box, enter the new joint. The Joint Type text box automatically updates to the selected type of joint. To select the joint from the screen, browse for a joint, or create a new joint, right-click the text box, and then select the appropriate command.

Initial condition text boxeschange depending on thetype of motion selected.


Applying Motion185

Change the direction of the motion (rotational or translational)

From the Direction option menu, select the motion direction. You can select only translational motion for a translational or cylindrical joint. You can select only rotational motion for a revolute or cylindrical joint.

Set the type of motion From the Type option menu, select how you want to define the magnitude of the motion.

Change the motion function defining the magnitude of the motion

Enter the following in the F(time) text box:■ Numerical value (For rotational motion,

specify the magnitude in radians.)

■ Function expression

■ Parameters to be passed to a user-written subroutine

To enter a function expression or values for a subroutine, right-click the F(time) text box, and then select Function Builder to display the ADAMS/View Function Builder. For information on using the Function Builder, see the guide, Using the ADAMS/View Function Builder.

Enter an initial condition

In the IC Displacement or IC Velocity text boxes, enter the initial conditions for displacement or velocity. The text boxes that appear depend on how the magnitude of the motion is defined.

Table 17. Options for Impose Joint Motion Dialog Box (continued)



Applying Motion186

Imposing Point MotionThere are two types of point motion that you can create:

■ Single point motion - Prescribes the motion of two parts along or around one axis.

■ General point motion - Prescribes the motion of two parts along or around the three axes (six DOF).

When you create a point motion, you specify the parts to which the motion is to be applied and the location and orientation of the motion. ADAMS/View creates coordinate system markers on each part at the location of the motion. The marker that ADAMS/View creates on the first part you select is called the moving point. It moves or rotates relative to the marker on the second part, called the reference marker. The z-axis of the reference marker defines the positive direction using the right-hand rule.

The next sections explain how to create and modify a point motion.

■ Creating a Point Motion, 187

■ Modifying a Point Motion, 189


Applying Motion187

Creating a Point Motion

The following procedure creates a point motion at a specified location on a part. It does not create a point motion on a joint. For information on imposing a point motion on a joint, see Imposing Point Motion on a Joint on page 161.

When you create a point motion, ADAMS/View creates a motion at the specified location.

■ For a single point motion, ADAMS/View defines the motion as a constant velocity over time, based on a speed value that you can enter. The speed value can be a numerical value, function expression, or user-written subroutine, as explained in Defining the Motion Magnitude on page 179.

By default, ADAMS creates the point motion around or along the z-axis. You specify the direction of the z-axis when you create the single point motion. You can change the axis around or along which the motion is applied.

■ For a general point motion, ADAMS/View creates a motion around or along all six coordinates of the markers created on the selected parts. It does not define the magnitude of the motion. You’ ll need to modify the motion to define its magnitude.


Applying Motion188

To create a point motion:

1 From the Motion tool stack or the Joint palette, select the tool representing the type of point motion that you want to create. Select either:

■ to create a single point motion.

■ to create a general point motion.


■ How you want the motion applied to parts. You can select the following:

■ 1 Location - Lets you select the location of the motion and have ADAMS/View determine the two parts to which it should be applied. ADAMS/View selects the parts closest to the motion location. If there is only one part near the motion, ADAMS/View connects the motion to that part and ground.

■ 2 Bodies - 1 Location - Lets you explicitly select the two parts to which the motion is to be applied and the location of the motion.

■ 2 Bodies - 2 Locations - Lets you explicitly select the two parts to which the motion is to be applied and the location of the motion on each part. You should use this option if you are working in exploded view. For more on exploded view, see Assembling Your Model on page 102 of the guide, Simulating Models in ADAMS/View.


■ How you want the motion oriented. You can select:

■ Normal to Grid - Lets you orient the motion along the current working grid, if it is displayed, or normal to the screen.

■ Pick Geometry Feature - Lets you orient the motion along a direction vector on a feature in your model, such as the face of a part.

■ If you are creating a single point motion, specify the direction of the motion from the Characteristic option menu and enter the speed of the motion in the Speed text box.


Applying Motion189

3 If you selected to explicitly select the parts to which the motion is to be applied, select each part using the left mouse button.

4 Place the cursor where you want the motion to be located and click the left mouse button. If you selected to specify its location on each part, place the cursor on the second location, and click the left mouse button.

5 If you selected to orient the joint along a direction vector on a feature, move the cursor around in your model to display an arrow showing the direction you want the motion oriented. When the direction vector shows the correct orientation, click the left mouse button.

Modifying a Point Motion

You can change several properties about a point motion. These include:

■ Parts or joints on which the motion is applied. If the motion is defined between two parts, you can change the coordinate system markers that define the location and orientation of the motion. You can also switch which point is the moving point (moves relative to second point) and which is the reference point. If the point motion is applied to a joint, you can also change the joint to which it is applied.

■ Axes or DOF of the parts to which the motion is applied.

■ General motion properties, including the following:

■ How the magnitude of the motion is defined (displacement, velocity, or acceleration)

■ Motion function, either a numerical value, function expression, or parameters to a user-written subroutine.


Applying Motion190

■ Initial conditions for displacements and velocities. ADAMS/View uses the initial conditions during an assemble model operation, which it runs before it runs a simulation of your model. You can specify the following initial conditions:

■ Initial displacement that defines the translation of the first part in units of length relative to the second part. You can set displacements on any point motion whose magnitude is defined as velocity or acceleration.

■ Initial velocity that define the velocity of the first part with respect to the second part in units of length per unit of time. You can set initial velocity on any point motion whose magnitude is defined as acceleration.

The following procedure explains how to modify a single or general point motion defined between two parts. The options available for modifying a general point motion between two parts are also the same options available for creating a general point motion on a joint. For information on creating a general point motion on a joint, see Imposing Point Motion on a Joint on page 161. Also refer to Table 18 for information on the options that you can set.

Note: You can also modify point motion using the Table Editor. For more information on editing objects using the Table Editor, see Editing Objects Using the Table Editor on page 401.


Applying Motion191

To modify a point motion:

1 Display the appropriate modify motion dialog box as explained in Accessing Modify Dialog Boxes on page 420.

If you are modifying a single point motion, the Impose Joint Motion dialog box appears. If you are modifying a general point motion, the Impose Motion(s) dialog box appears. Each dialog box is shown below.

The Impose Point Motion has only one set of options, while the Impose Motion(s) dialog box displays a set of options for each of the six DOF. It displays an option menu next to a DOF if it is free and can have motion applied to it, and displays the label fixed if the DOF is constrained and cannot move.

Figure 66. Impose Point Motion Dialog Box

Initial condition text boxeschange depending on thetype of motion selected.


Applying Motion192

Figure 67. Impose Motion(s) Dialog Box

2 If desired, in the Moving Point and Reference Point text boxes, change the coordinate system markers that define the location and orientation of the motion on the parts.

To select a marker from the screen, browse for a marker in the Database Navigator, or create a marker, right-click the text box, and then select the appropriate command.

3 Enter the values in the dialog box for each DOF to which you want to apply motion to as explained in Table 18 on page 193, and then select OK.


Applying Motion193

Table 18. Options for Impose Motions Dialog Box


Set the type of motion From the Type option menu, select how you want to define the magnitude of motion.

Change the motion function defining the magnitude of the motion

Enter the following in the F(time) text box:■ Numerical value (For rotational motion,

specify the magnitude in radians.)



To enter a function expression or parameters for a subroutine, right-click the F(time) text box, and then select Function Builder to display the ADAMS/View Function Builder. For information on using the Function Builder, see the guide, Using the ADAMS/View Function Builder.

Enter an initial condition

In the IC Displacement or IC Velocity text boxes, enter the initial conditions for displacement or velocity. The text boxes that appear depend on how the magnitude of the motion is defined.


Applying Motion194

7 Applying Forces to Your Model

OverviewYou use forces to model elastic connections between parts, spring and damping elements, actuation and control forces, and many other part interactions. This chapter introduces forces and explains how to create and modify forces. It contains the sections:

■ About Forces, 196

■ Defining Forces in ADAMS/View, 197

■ Force Naming Conventions, 200

■ Accessing the Force Tools, 201

■ Constructing Applied Forces, 203

■ Constructing Flexible Connectors, 226

■ Working with Modal Forces in ADAMS/View, 265

■ Viewing Modal Preloads of Flexible Bodies, 270


Applying Forces to Your Model196

About ForcesForces define loads and compliances on parts. Forces do not absolutely prohibit or prescribe motion. Therefore, they do not add or remove degrees of freedom (DOF) from your model. Some forces can resist motion, such as spring-dampers, and some can try to induce motion.

ADAMS/View provides the following types of forces:

■ Applied forces - Applied forces are forces that define loads and compliances on parts. Applied forces are very general, but you must supply your own description of the force behavior by specifying a constant force value, ADAMS/View function expression, or parameters to a user-written subroutine that is linked into ADAMS/View.

■ Flexible connectors - Flexible connectors resist motion and are simpler and easier to use than applied forces because you only supply constant coefficients for the forces. The forces include beams, bushings, translational spring-dampers, and torsion springs that provide compliant force relationships.

■ Special forces - Special forces are forces that are commonly encountered, such as tire and gravity forces. For more on gravity and setting gravity, see Specifying Gravitational Force on page 40 of the guide, Learning ADAMS/View Basics. For more information on defining tires, see the guide, Using ADAMS/Tire.

■ Contacts - Specify how parts react when they come in contact with each other when the model is in motion.



Defining Forces in ADAMS/ViewFor every force that you define in ADAMS/View, you specify the following information:

■ Whether the force is translational or rotational.

■ To which part or parts the force is applied.

■ At what point or points is the force applied (only applies to translational forces).

■ Magnitude and direction of the force.

The following two sections explain in more detail how to define forces in ADAMS/View:

■ Defining Force Magnitude, 198

■ Defining Force Directions, 199



Defining Force Magnitude

When defining a force’ s magnitude, you can either define it as one resultant magnitude along a direction, or you can resolve the resultant into as many as three components that are associated with the three mutually perpendicular axes of a particular coordinate system.

You can define force magnitudes in ADAMS/View in the following ways:

■ Enter values used to define stiffness and damping coefficients. In this case, ADAMS/View automatically makes the force magnitude proportional to the distance and velocity between two points. The coefficients represent the proportionality constants. You specify coefficients for flexible connectors, such as spring-dampers and beams. You can also specify these values for applied forces.

■ Enter a function expression using the ADAMS/View library of built-in functions. You can enter expressions for all types of applied forces. Built-in functions include the types listed below. For more information on using expressions and available functions, see the guide, Using the ADAMS/View Function Builder.

■ Displacement, velocity, and acceleration functions that allow the force to be related to the movement of points or bodies in the system. Examples include springs and viscous dampers.

■ Force functions that allow the force to depend on other forces in the system. An example would be a Coulomb friction force that is proportional to the normal force between two bodies.

■ Mathematical functions such as sine and cosine, series, polynomials, steps, and more.

■ Spline functions that allow the force to depend on data stored in lookup tables. Examples of these include motors using torque-speed curves or nonlinear bushings whose stiffness is not entirely linear.

■ Impact functions that make the force act like a compression-only spring-damper that turns on and off as bodies intermittently contact one another.



■ Enter parameters that are passed to user-written subroutines that are linked to ADAMS/View. You can enter parameters for all types of applied forces. You can also enter parameters to a subroutine for the field flexible connector to create a nonlinear force between two parts. For more information on how to use subroutines to define your force magnitudes, see the guide, Using ADAMS/Solver Subroutines.

Defining Force Directions

You can define force directions in ADAMS/View in one of two ways:

■ Along one or more of the axes of a coordinate system marker.

■ Along the line-of-sight between two points.

If your force direction remains fixed with respect to some part in your model, either a moving part or the ground part, then you can define the force using one vector component and specify only one magnitude and direction.

If you have two or more forces whose directions always remain perpendicular to one another (such as a normal force and a friction force), you can either define multiple single-component forces whose directions are perpendicular or you can use a multiple-component force element. You must define several expressions, one for each of the force magnitudes you need.

If the direction along which you want the force applied is defined by the line between two points in your model and is constantly changing throughout the simulation, you only need to define one component of force along this direction and one expression for the corresponding force magnitude.

As you define forces, ADAMS/View gives you shortcuts for defining the force application. These shortcuts allow you to let ADAMS/View automatically create the force definition using only a few clicks of the mouse. For example, as you create a bushing, you can simply specify one location. ADAMS/View automatically determines the parts which should be included. You can also specify that the force be aligned to the coordinates of the working grid or screen or a feature of a part. Each section of the guide that describes the force also describes how to use the shortcuts.



Force Naming ConventionsAs you create forces, ADAMS/View automatically generates names for them based on their type and the number of objects of that type in your model. For example, when you create a single-component force, ADAMS/View assigns it the name SFORCE followed by an underscore and its number (for example, SFORCE_1).

You can rename your forces as desired. For more information, see Renaming Objects on page 425.



Accessing the Force ToolsYou can create forces using the tools on the Create Forces palette or the Create Forces tool stack on the Main toolbox. Note that the palette contains more tools for creating contacts. The Create Forces palette and tool stack are shown below. For more on palettes and tool stacks, see Using Toolboxes and Toolbars on page 47 of the guide, Learning ADAMS/View Basics.

Figure 68. Create Forces Palette and Tool Stack

Create Forces tool stackon Main toolbox

Settingscontainer

Create Forces palette



As you create forces, ADAMS/View provides basic settings that you can control. It provides the settings in a container at the bottom of the palette or Main toolbox. The settings change depending on the type of force that you are creating. For example, Figure 68 shows the stiffness and damping coefficients for creating a translational spring-damper.

You can use the settings to control how you want ADAMS/View to create forces. You can also define design variables or expressions for these setting values.

To display the Create Forces palette:

■ From the Build menu, select Forces.

To display the contents of the Create Forces tool stack:

■ From the Main toolbox, right-click the Create Forces tool stack. By default,

the Translational Spring-Damper tool appears at the top of the tool stack.



Constructing Applied ForcesApplied forces are forces that define loads and compliances on parts so they move in certain ways. ADAMS/View provides a library of applied forces that you can use. Applied forces give you a great deal of flexibility, but they require work to model simple forces. Instead of using applied forces, you may want to consider using the flexible connectors, which model several commonly used force elements, or special forces, which provide environmental and complex forces.

The next sections explain more about applied forces:

■ About Applied Forces, 203

■ Constructing Single-Component Forces, 205

■ Constructing Multi-Component Forces, 216

About Applied Forces

Applied forces can have one, three, or six components (three translational and three rotational) that define the resultant force. For example, a single-component force or torque defines the force using a single component, while a multi-component force or torque defines the force using three or more components. The following figure shows all six possible force components associated with a particular coordinate system’ s x-, y-, and z-axis.

Figure 69. Possible Components of an Applied Force

TyFy

Tx,

,

TzFz

Fx

,

zy

x



As you create applied forces, you specify:

■ Parts to which the force is applied and its direction - You can apply the force to two parts or to one part and ground. ADAMS/View creates a marker on each part. The first part you select is the action body and receives the force action. The second part you select is the reaction body and receives the force reaction. If you specify one part and ground, the reaction force is on the ground part, and, thus, has no effect on your model.

■ Characteristic, which defines the magnitude of the force. You can specify:

■ Constant force - You enter a constant force value. When ADAMS/View creates the force, it uses the value you enter as the force function. When you modify the force, you can change the value or enter a function expression or parameters to a user-written subroutine as explained for the Custom option below.

■ Bushing- or spring-like - ADAMS/View creates a function expression defining the linear stiffness and damping forces based on the stiffness and damping coefficients that you specify.

■ Custom - You define the magnitude of the force as a function of any combination of displacements, velocities, other applied forces, user-defined variables, and time. You can write a function expression or enter parameters to be passed to a user-written subroutine (for example, SFOSUB or VFOSUB) that is linked into ADAMS/View. You define the constitutive equation for the force applied to the action body. ADAMS/View evaluates the reaction forces on the reaction body.

ADAMS/View evaluates the signed magnitude of the force and applies it to the selected body or bodies.



Constructing Single-Component Forces

ADAMS/View provides two forces that are defined as a single component: single-component force and single-component torque. The following sections explain more about these single-component forces and how to create and edit them:

■ Single-component Force, 206

■ Single-Component Torque, 207

■ Specifying Force Direction, 208

■ Creating a Single-Component Force, 210

■ Modifying a Single-Component Force, 212



Single-component Force

A single-component force applies a translational force in one of two ways:

■ To one movable part - You select the part, the location of the point of application, and the direction. ADAMS/View automatically applies the force to ground.

■ To two parts - You select the parts and the locations of the point of application on each part. ADAMS/View automatically defines the direction based on the line of sight between the two locations. The direction is continuously updated during simulation.

Figure 70 shows an example of a single-component force applied to a part.

Figure 70. Example of a Single-component Force

Note: You cannot use the line-of-sight method if the two points that define the force will become coincident during a simulation because the force direction becomes undefined. When running a simulation, ADAMS/Solver warns you when the points become nearly coincident. The following shows an example of a warning:

WARNING: The direction cosines for SFORCE model_1.FORCE_1 are invalid. This is usually caused by a (nearly) zero length SFORCE or SPRINGDAMPER.

You can ignore the warning only if the computed force is zero when the points are coincident (for example, when you are using a BISTOP function that is inactive when its markers are coincident). Otherwise, having coincident points is a modeling error with unpredictable results.

FAPoint of application*

Action Body

Ground



Single-Component Torque

A single-component torque applies a rotational force to either one part or two about a specified axis. You specify the point of application and the direction. Figure 71 shows an example of a single-component torque applied to one part.

Figure 71. Example of Single-Component Torque

Point of Application

TA

*

Action Body



Specifying Force Direction

When you create a single-component force, you have three options for specifying the number of parts affected and the direction of the force:

■ Space fixed - Applies the single-component force to one part, or action body, that you select. ADAMS/View automatically applies the reaction force to ground. You specify a direction for the force. The direction never changes. It remains fixed in space during the simulation, even if the action body moves because the coordinate system marker used to define the force direction is attached to the ground part.

Figure 72. Example of Space Fixed**

*

F1

F1

F1



■ Body moving - Applies the single-component force to one part, or action body, that you select. ADAMS/View automatically applies the reaction force to ground. You specify a direction for the force. The direction can change during the simulation because the coordinate system marker used to define the force direction is attached to the action body. You can attach the direction marker to a different part when you modify the force.

Figure 73. Example of Body Fixed

■ Two bodies - Applies the single-component force to two parts that you select, at two locations that you select. ADAMS/View defines the direction based on the line of sight between the two locations you selected.

Figure 74. Example of Two Bodies

*

**

F1

F1

F1

**

F2

F1



Creating a Single-Component Force

To create a single-component force:

1 From the Create Forces tool stack or palette, select either:

■ to create a single-component force.

■ to create a single-component torque.


■ The number of parts and the nature of the force direction. You can select the following:

■ Space Fixed

■ Body Moving

■ Two Bodies

For more on the effects of these options, see Specifying Force Direction on page 208.

■ How you want the force oriented. You can select:

■ Normal to Grid - Lets you orient the force normal to the current working grid, if it is displayed, or normal to the screen.

■ Pick Feature - Lets you orient the force along a direction vector on a feature in your model, such as along an edge or normal to the face of a part.



■ The characteristics of the force. You can select the following:

■ Constant force/torque - Enter a constant force or torque value or let ADAMS/View use a default value.

■ Spring-Damper - Enter stiffness and damping coefficients and let ADAMS/View create a function expression for damping and stiffness based on the coefficient values. (Not available when you are using the Main toolbar to access the force tool.)

■ Custom - ADAMS/View does not set any values for you, which, in effect, creates a force with zero magnitude. After you create the force, you modify it by entering a function expression or parameters to a user-written subroutine that is linked to ADAMS/View.

3 Do one of the following depending on whether you are creating a single-component force or torque:

■ For a single-component force, select the action body. If you selected to create a torque between two parts, select the reaction body and then select the points of application on the two bodies. Be sure to select the point of application on the action body first.

■ For a single-component torque, select the action body. If you selected to create a torque between two parts, select the reaction body and then select the points of application on the two bodies. Be sure to select the point of application on the action body first.

4 If you selected to orient the force along a direction vector on a feature, move the cursor around in your model to display an arrow representing the direction along a feature where you want the force oriented. When the direction vector represents the desired orientation, click.



Modifying a Single-Component Force

You can modify the following for a single-component force or torque:

■ Force direction, if only one part is affected.

■ Action body to which the force is applied. If you created the force between two parts, you can also change the reaction body. You cannot change a force created on one part and ground to a force created between two parts because the direction methods are not compatible. You’ ll have to delete the force and create it again.

■ Force magnitude, either a constant force value, function expression, or parameters to a user-written subroutine.

■ Whether or not force graphics are displayed during an animation. Force graphics display an arrow in the direction of the force. The length of the arrow is proportional to the magnitude of the force. By default, ADAMS/View turns on all single-component force graphics. For information on setting preferences for force graphics, see Setting Up Force Graphics on page 201 of the guide, Simulating Models in ADAMS/View.



To modify a single-component force:

1 Display the Modify a Force or Modify a Torque dialog box as explained in Accessing Modify Dialog Boxes on page 420.

The dialog box appears. The options available in the dialog box change depending on the direction of the force. The following shows the Modify a Force dialog box when the force was defined as applied to one part with the direction of the force moving with a direction body.

2 Enter the values in the dialog box as explained in Table 19 and select OK.



Table 19. Options for Modifying a Single-Component Force


Set the number of parts affected and the direction of the force

From the Direction option menu, select how you want to define the direction of the force. The options in the dialog box change depending on your selection. ■ On One Body, Fixed in Space - Sets the force direction so it

is applied to a part. The force direction is fixed on ground.

■ On One Body, Moving with Body - Sets the force so it is applied to a part. The part defines the direction of the force.

■ On One Body, Moving with Another Body - Sets the force so it is applied to a part. A second part (the direction part) defines the direction of the force.

■ Between Two Bodies - Creates a force between two parts. One of the parts can be ground. You cannot change a force on one part to a force defined between two parts or the reverse. You can, however, change a torque on one part to a torque on two parts or the reverse.



Set the bodies used in defining the force

Change the values in the following text boxes as necessary. The text boxes available depend on how you defined the direction of the force. ■ Body - Change the action body to which the force is

applied.

■ Reaction Body - Change the body that receives the reaction forces.

■ Direction Body - Change the body that defines the direction of the force if you selected the direction option, On One Body, Moving with Another Body.

To select a part from the screen or browse for a part in the Database Navigator, right-click the text box, and then select the appropriate command.

Change the force function defining the magnitude of the force

Enter the following in the F(time, ...) text box:■ Constant force value



To enter a function expression or parameters for a subroutine, right-click the F(time, ...) text box, and then select Function Builder to display the ADAMS/View Function Builder. For information on using the Function Builder, see the guide, Using the ADAMS/View Function Builder.

Set force graphics From the Force Display option menu, select whether you want to display force graphics for one of the parts, both, or none. By default, ADAMS/View displays the force graphic on the action body for single-component forces.

Table 19. Options for Modifying a Single-Component Force (continued)




Constructing Multi-Component Forces

ADAMS/View provides three forces that are defined as three or more components. The following sections explain more about these multi-component forces and how to create and edit them:

■ About Multi-Component Forces, 216

■ Calculating Total Force Magnitudes, 218

■ Applying Multi-Component Forces to Parts, 220

■ Creating a Multi-Component Force, 221

■ Modifying a Multi-Component Force, 223

About Multi-Component Forces

To define more complex forces, you can use multi-component forces. Multi-component forces apply translational and/or rotational force between two parts in your model using three or more orthogonal components. The following lists the different types of multi-component forces:

■ Three-component force

■ Three-component torque

■ Six-component general force

A multi-component force applies an action force to the first part you select, which is called the action body. ADAMS/View automatically applies a corresponding reaction force to the second part you select, which is called the reaction body. If you define the force characteristics as bushing-like, ADAMS/View generates equations to represent a linear spring-damper in the specified component directions.

To define the points of application of the multi-component force, ADAMS/View creates a coordinate system marker for each part. The marker belonging to the action body is the action marker, and the marker belonging to the reaction body is the reaction marker. ADAMS/View keeps the reaction marker coincident with the action



marker at all times. The reaction marker is often referred to as a floating marker because its location is not fixed relative to the body to which it belongs. Action and reaction markers are also referred to as I and J markers.

ADAMS/View also creates a third coordinate system marker called a reference (R) marker that indicates the direction of the force. You define the orientation of the reference marker when you create a multi-component force. You can align the marker to the working grid, if it is turned on, or to the global coordinate system. You can also orient the marker using any feature in your model, such as along an edge of a part.

Figure 75 illustrates the movement of reaction forces and the placement of the reference marker. The figure shows a ball bouncing on a board. As the ball bounces, its location changes relative to the board. The reaction forces applied to the board also change location because the reaction (J) marker moves with the ball. The reaction forces applied to the board do not change direction because the reference (R) marker belongs to the stationary board.

Figure 75. Example of Action and Reaction Force Movement

Tip: You can use the Info command to see the markers that ADAMS/View creates for a multi-component force. You can also see the markers when you modify the force. For more information on the Info command, see Viewing Modeling Information on page 171 of the guide, Learning ADAMS/View Basics.

Reactionbody

Fr (applied to reaction body)

Action

to action body)Fa (applied

Action andreaction markerscoincident

Referencemarker

body



Calculating Total Force Magnitudes

The following sections explain how ADAMS/View calculates the total force and/or torque of a multi-component force:

■ Total Force Equations, 218

■ Total Torque Equations, 219

Total Force Equations

For a six-component general force and a three-component force, the total force that ADAMS/Solver, the analysis engine, supplies is the vector sum of the individual force components that you specify. Its magnitude is the square root of the sum of the squares of the three mutually-orthogonal force components:

a = FX rm + FY rm + FZ rm

where:

■ a is the action applied to the action body.

■ FX is the user-defined function defining the magnitude and sign of the x-component.

■ FY is the user-defined function defining the magnitude and sign of the y-component.

■ FZ is the user-defined function defining the magnitude and sign of the z component.

■ rm is a unit vector along the + x direction of the reference marker.

■ rm is a unit vector along the + y direction of the reference marker.

■ rm is a unit vector along the + z direction of the reference marker.

The values of the reaction forces are:

r = - a

where r is the reaction force applied to the reaction body. If you apply the force to a part and ground, ADAMS/Solver does not calculate the reaction forces.

F x y z

F

x

y

z

F F

F



Total Torque Equations

For a six-component general force and a three-component torque, the magnitude of the torque is the square root of the sum of the squares of the magnitudes of the three mutually orthogonal torque components, such that:

a = TX rm + TY rm + TZ rm

where:

■ a is the action applied to the action body.

■ TX is the user-defined function defining the magnitude and sign of the x component according to the right-hand rule.

■ TY is the user-defined function defining the magnitude and sign of the y component according to the right-hand rule.

■ TZ is the user-defined function defining the magnitude and sign of the z component according to the right-hand rule.

■ rm is a unit vector along the + x direction of the reference marker.

■ rm is a unit vector along the + y direction of the reference marker.

■ rm is a unit vector along the + z direction of the reference marker.

The reaction torque applied to the reaction body is:

r = - a

where r is the reaction torque applied to the reaction body. If you apply the torque to a part and ground, ADAMS/Solver does not calculate the reaction torques.

T x y z

T

x

y

z

T T

T



Applying Multi-Component Forces to Parts

When you create multi-component forces, ADAMS/View provides you with shortcuts for specifying the parts to which the force is to be applied. As you create a multi-component force, you can select one of the methods listed below. These methods also apply to bushings, fields, and torsion springs.

■ 1 Location - Lets you select the location of the force and have ADAMS/View determine the two parts to which it should be applied. ADAMS/View selects the parts closest to the point of application. If there is only one part near the point, ADAMS/View applies the force to that part and ground. Note that letting ADAMS/View select the parts is only appropriate when two parts are located near each other and when it does not matter which part is the action body and which is the reaction body.

■ 2 Bodies - 1 Location - Lets you select the two parts to which the force will be applied and the common point of application on each part. The first part you select is the action body; the second part is the reaction body.

■ 2 Bodies - 2 Locations - Lets you select the two parts to which the force is applied and a different location for the force on each part. If the markers defining the locations of the forces are not coincident and aligned, the forces may be non-zero at the beginning of the simulation.

Table 20 summarizes the bodies and locations you specify as you create a force.

Tip: To precisely orient your force, first orient the working grid so its x-, y-, and z-axes align with the desired force axes. Then, use the Normal To Grid orientation method when you create the force. For more information on the working grid, see Setting the Location and Orientation of the Working Grid on page 133 of the guide, Learning ADAMS/View Basics.

Table 20. Comparison of Methods

The method: Number of bodies: Number of points:

1 Location 0 1

2 Bodies - 1 Location 2 1

2 Bodies - 2 Locations 2 2



Creating a Multi-Component Force

To create a multi-component force:

1 From the Create Forces tool stack or palette, select the tool representing the multi-component force that you want to create. Select:

■ to create a three-component force.

■ to create a three-component torque.

■ to create a six-component general force.


■ The method you want to use to define the bodies and force-application points. You can select the following:

■ 1 location

■ 2 bodies - 1 location

■ 2 bodies - 2 locations

For more on the effects of these options, see Applying Multi-Component Forces to Parts on page 220.


■ Normal to Grid - Lets you orient the force using the x-, y-, and z-axes of the current working grid, if it is displayed, or using the x-, y-, and z-axes of the screen.

■ Pick Feature - Lets you orient the force along direction vectors on features in your model, such as the face of a part. The direction vectors you select define the x- and y-axes; ADAMS/view calculates the z-axis automatically.



■ The characteristics of the force. You can select the following:

■ Constant force/torque - Enter constant force or torque values or let ADAMS/View use default values.

■ Bushing-like - Enter stiffness and damping coefficients and let ADAMS/View create a function expression for damping and stiffness based on the coefficient values.

■ Custom - ADAMS/View does not set any values for you. After you create the force, you modify it to enter function expressions or parameters to a user-written subroutine that is linked to ADAMS/View.

3 Click the bodies.

4 Click one or two force-application points depending on the location method you selected.

5 If you selected to orient the force along direction vectors using features, move the cursor around in your model to display an arrow that shows the direction along a feature where you want the force oriented. Click when the direction vector shows the correct x-axis orientation and then click again for the y-axis orientation.



Modifying a Multi-Component Force

You can modify the following for a multi-component force or torque:

■ Action and reaction body to which the force is applied or the action and reaction markers.

■ Reference marker.

■ Force magnitude—either a constant force value, function expression, or parameters to a user-written subroutine.

■ Whether or not force graphics are displayed during an animation. Force graphics display an arrow in the direction of the force. The length of the arrow is proportional to the magnitude of the force. By default, ADAMS/View turns on force graphics for the action body. For information on setting preferences for force graphics, see Setting Up Force Graphics on page 201 of the guide, Simulating Models in ADAMS/View.



To modify a multi-component force:

1 Display a modify dialog box as explained in Accessing Modify Dialog Boxes on page 420.

The Modify General Force dialog box appears. The options available in the dialog box change depending on the type of multi-component force. The following shows the Modify General dialog box that appears for a six-component general force.

2 Enter the values in the dialog box as explained in Table 21, and then select OK.

Options availabledepend on numberand type of forcecomponents



Table 21. Options for Modifying a Force or Torque


Set the bodies or markers used in defining the force

From the option menus, select whether or not you want to define the force using bodies or markers. Then, enter values in the text boxes, as appropriate. The text boxes that are available depend on how you defined the direction of the force. ■ Action Part/Action Marker - Change the action body or

marker to which the force is applied.

■ Reaction Part/Reaction Marker - Change the reaction body or marker that receives the reaction forces.

To select an object from the screen or browse for an object in the Database Navigator, right-click the text box, and then select the appropriate command.

Change how the characteristics of the force are defined

Do one of the following:■ From the Define Using option menu, select Function and

enter either a constant force value or function expression for each component of the force.

■ From the Define Using option menu, select Subroutine and enter the parameters to be passed to the user-written subroutine.

To enter a function expression, right-click the component text box, and then select Function Builder to display the ADAMS/View Function Builder. For information on using the Function Builder, see the guide, Using the ADAMS/View Function Builder.

Set force graphics From the Force Display option menu, select whether you want to display force graphics for one of the parts, both, or none. By default, ADAMS/View displays force graphics for the action body.



Constructing Flexible ConnectorsFlexible connectors let you connect two bodies in a compliant way. In contrast to joints, which are rigid connectors, flexible connectors do not absolutely prohibit any part movement and, therefore, do not remove any degrees of freedom (DOF) from your model. Flexible connectors do typically resist movements between parts, however, by applying spring and damper forces to the connected bodies.These forces are proportional to the displacement and rate of change in displacement between two parts, respectively.

The following sections explain each of the types of flexible connectors.

■ Working with Bushings, 226

■ Working with Translational Spring-Dampers, 233

■ Adding a Torsion Spring, 238

■ Adding a Massless Beam, 244

■ Adding a Field Element, 255

Working with Bushings

A bushing is a linear force that represents the forces acting between two parts over a distance. The bushing applies a force and a torque. You define the force and torque using six components (Fx, Fy, Fz, Tx, Ty, Tz).

To define a bushing, you need to create two coordinate system markers, one for each part. The marker on the first part that you specify is called the I marker. The marker on the second part that you specify is called the J marker.

The next sections explain more about bushings:

■ Constitutive Equations for Bushings, 227

■ Creating a Bushing, 229

■ Modifying a Bushing, 231



Constitutive Equations for Bushings

The following constitutive equations define how ADAMS/View uses the data for a linear bushing to apply a force and a torque to the action body depending on the displacement and velocity of the I marker on the action body relative to the J marker on the reaction body.

Note: A bushing has the same constitutive relation form as a field element. The primary difference between the two forces is that nondiagonal coefficients (Kij and Cij, where i is not equal to j) are zero for a bushing. You only define the diagonal coefficients (Kii and Cii) when creating a bushing. For more on field elements, see Adding a Field Element on page 255.

Fx

Fy

Fz

Tx

Ty

Tz

K11 0 0 0 0 0

0 K22 0 0 0 0

0 0 K33 0 0 0

0 0 0 K44 0 0

0 0 0 0 K55 0

0 0 0 0 0 K66

x

y

z

a

b

c

–=

C11 0 0 0 0 0

0 C22 0 0 0 0

0 0 C33 0 0 0

0 0 0 C44 0 0

0 0 0 0 C55 0

0 0 0 0 0 C66

Vx

Vy

Vz

ωx

ωy

ωz

–

F1

F2

F3

T1

T2

T3

+



where:

■ Fx, Fy, and Fz are measure numbers of the translational force components in the coordinate system of the J marker.

■ x, y, and z are measure numbers of the bushing deformation vector in the coordinate system of the J marker.

■ Vx, Vy, and Vz are time derivatives of x, y, and z, respectively.

■ F1, F2, and F3 are measure numbers of any constant preload force components in the coordinate system of the J marker.

■ Tx, Ty, and Tz are rotational force components in the coordinate system of the J marker.

■ a, b, and c are projected, small-angle rotational displacements of the I marker with respect to the J marker.

■ ωx, ωy, and ωz are the measure numbers of the angular velocity of the I marker as seen by the J marker, expressed in the J marker coordinate system.

■ T1, T2, and T3 are measure numbers of any constant preload torque components in the coordinate system of the J marker.

The bushing element applies an equilibrating force and torque to the J marker in the following way:

Fj = - F

i

Tj = - T

i - δ Fi

δ is the instantaneous deformation vector from the J marker to the I marker. While the force at the J marker is equal and opposite to the force at the I marker, the torque at the J marker is usually not equal to the torque at the I marker because of the moment arm due to the deformation of the bushing element.

×



Note: For the rotational constitutive equations to be accurate, at least two of the rotations (a, b, c) must be small. That is, two of the three values must remain smaller than 10 degrees. In addition, if a becomes greater than 90 degrees, b becomes erratic. If b becomes greater than 90 degrees, a becomes erratic. Only c can become greater than 90 degrees without causing convergence problems. For these reasons, it is best to define your bushing such that angles a and b remain small (not a and c and not b and c).

Creating a Bushing

To create a bushing:

1 From the Create Forces tool stack or palette, select the Bushing tool .


■ How you want the force applied to parts. You can select the following:

■ 1 location






■ Pick Feature - Lets you orient the force along a direction vector on a feature in your model, such as the face of a part. The direction vector you select defines the z-axis for the force; ADAMS/View calculates the x- and y-axes automatically.

■ The translational and rotational stiffness and damping properties for the bushing.

3 Click the bodies.




5 If you selected to orient the force along a direction vector using a feature, move the cursor around in your model to display an arrow that shows the direction along a feature where you want the force oriented. Click when the direction vector shows the correct z-axis orientation.



Modifying a Bushing

You can modify the following for a bushing:

■ The two bodies to which the forces are applied.

■ Translational and rotational properties for stiffness, damping, and preload.

■ Whether or not force graphics are displayed during an animation. Force graphics display an arrow in the direction of the force. The length of the arrow is proportional to the magnitude of the force. By default, ADAMS/View turns on force graphics for the action body. For information on setting preferences for force graphics, see Setting Up Force Graphics on page 201 of the guide, Simulating Models in ADAMS/View.

To modify a bushing:

1 Display the Modify Bushing dialog box as explained in Accessing Modify Dialog Boxes on page 420.

2 Enter the values in the dialog box as explained in Table 22 and select OK.

Table 22. Options for Modifying Bushing


Set the bodies used in defining the force

Change the following as necessary in the following text boxes. The text boxes available depend on how you defined the direction of the force. ■ Action Body - Change the action body to which the force is

applied.

■ Reaction Body - Change the body that receives the reaction forces.

To select a part from the screen or browse for a part in the Database Navigator, right-click the text box, and then select the appropriate command.



Change the properties of the force

Do the following:■ For the translational force applied by the bushing, enter:

■ Three stiffness coefficients.

■ Three viscous damping coefficients. The force due to damping is zero when there are no relative translational velocities between the markers on the action and reaction bodies.

■ Three constant force (preload) values. Constant values indicate the magnitude of the force components along the x-, y-, and z-axis of the coordinate system marker of the reaction body (J marker) when both the relative translational displacement and velocity of the markers on the action and reaction bodies are zero.

■ For the rotational force (torque) applied by the bushing, enter the following:

■ Three stiffness coefficients.

■ Three viscous damping coefficients. The torque due to damping is zero when there are no relative rotational velocities between the markers on the action and reaction bodies.

■ Three constant torque (preload) values. Constant values indicate the magnitude of the torque components about the x-, y-, and z-axis of the coordinate system marker on the reaction body (J marker) when both the relative rotational displacement and velocity of the markers on the action and reaction bodies are zero.

Set force graphics

From the Force Display option menu, select whether you want to display force graphics for one of the parts, both, or none.

Table 22. Options for Modifying Bushing (continued)




Working with Translational Spring-Dampers

A spring-damper (shown in Figure 76) represents forces acting between two parts over a distance and along a particular direction. You specify the locations of the spring-damper on two parts. ADAMS/View calculates the spring and damping forces based on the distance between the locations on the two parts. It applies the action force to the first part you select, called the action body, and applies an equal and opposite reaction force along the line of sight to the second part you selected, called the reaction body.

Figure 76. Example of a Spring-Damper

You can specify the damping and stiffness values as coefficients or use a spline to define the relationship of damping to velocity or stiffness to displacement. You can also set the stiffness value to 0 to create a pure damper or set the damping value to 0 to create a pure spring.

You can also set the length of the spring-damper when it is in its preloaded state and any preload forces on the spring. By default, ADAMS/View uses the length of the spring-damper when you create it as its preload length.

The next sections explain more about creating and modifying spring-dampers.

■ Equations Defining the Force of a Spring-Damper, 234

■ Creating a Spring-Damper, 234

■ Modifying a Spring-Damper, 235

FR

*FA> 0

positive

FR = - FAAction

Reaction

Body

Body



Equations Defining the Force of a Spring-Damper

The magnitude of the translational force of a spring-damper is linearly dependent upon the relative displacement and velocity of the two locations that define the endpoints of the spring-damper. The following linear relation describes the force:

force = -C(dr/dt) - K(r - LENGTH) + FORCE

where:

■ r is the distance between the two locations that define the spring damper.

■ dr/dt is the relative velocity of the locations along the line-of-sight between them.

■ C is the viscous damping coefficient.

■ K is the spring stiffness coefficient.

■ FORCE (preload) defines the reference force of the spring.

■ LENGTH (displacement at preload) defines the reference length.

Creating a Spring-Damper

You add a translational spring-damper to your model by defining the locations on two parts between which the spring-damper acts. You define the action force that is applied to the first location, and ADAMS/Solver, the analysis engine, automatically applies the equal and opposite reaction force to the second location.

To create a spring-damper:

1 From the Create Forces palette or tool stack, select the Translational Spring-Damper

tool .

2 If desired, enter stiffness (K) and damping (C) coefficients in the Settings container.

3 Select a location for the spring-damper on the first part. This is the action body.

4 Select a location for the spring-damper on the second part. This is the reaction body.



Modifying a Spring-Damper

After you’ve created a spring-damper, you can modify:

■ Parts between which the spring-damper acts.

■ Stiffness and damping values, including specifying a spline that defines the relationship of stiffness to displacement. For more information on defining splines, see Creating Data Element Splines on page 332.

■ Preload values.

■ Whether or not spring, damper, and force graphics appear.

■ Spring and damper graphics - You can specify that spring and damper graphics are always on, always off, or on whenever you have defined a spring or damping coefficient.

■ Force graphics - You can select to display force graphics for either part to which the force is applied. Force graphics display an arrow in the direction of the force. The length of the arrow is proportional to the magnitude of the force. By default, ADAMS/View turns on force graphics for the action body. For information on setting preferences for force graphics, see Setting Up Force Graphics on page 201 of the guide, Simulating Models in ADAMS/View.

To modify a spring-damper:

1 Display the Modify a Spring Damper Force dialog box as explained in Accessing Modify Dialog Boxes on page 420.

2 In the Action Body and Reaction Body text boxes, change the parts to which the spring-damper force is applied, if desired.

3 Enter values for stiffness and damping as explained in Table 23 on page 236, and then select OK.



Table 23. Options for Stiffness and Damping

To set: Do the following:

Stiffness Select one of the following:■ Stiffness Coefficient and enter a stiffness

coefficient for the spring-damper.

■ No Stiffness to turn off all spring forces and create a pure damper.

■ Spline: F=f(defo) and enter a spline that defines the relationship of force to deformation. (For information on defining splines, see Creating Data Element Splines on page 332.)

To select a spline from the screen or browse for a spline in the Database Navigator, right-click the text box, and then select the appropriate command.

Damping Select one of the following:■ Damping Coefficient and enter a viscous damping

coefficient for the spring-damper.

■ No Damping to turn off all damping forces to create a pure spring.

■ Spline: F=f(velo) and enter a spline that defines the relationship of force to velocity. (For information on defining splines, see Creating Data Element Splines on page 332.)




Preload and length of spring

Do the following:■ In the Preload text box, enter the preload force

for the spring-damper. Preload force is the force of the spring-damper in its unloaded (preload) position.

■ Select one of the following:

■ Default Length to use the length of the spring-damper when you created it as its preload position.

■ Length at Preload and enter the length of the spring at its preload position.

Tip: If you set preload to zero, then displacement at preload is the same as the spring’ s free length. If the preload value is non-zero, then the displacement at preload is not the same as the spring’s free length.

Set graphics From the option menus, select whether you want spring, damper, or force graphics.

Table 23. Options for Stiffness and Damping (continued)




Adding a Torsion Spring

The next sections explain more about torsion springs and how to create and modify them:

■ About Torsion Springs, 238

■ Creating a Torsion Spring, 240

■ Modifying a Torsion Spring, 241

About Torsion Springs

A torsion spring force is a rotational spring-damper applied between two parts. It applies the action torque to the first part you select, called the action body, and applies an equal and opposite reaction torque to the second part you select, called the reaction body.

ADAMS/View creates a coordinate system marker at each location. The marker on the first location you specify is called the I marker. The marker on the second location that you specify is called the J marker. The right-hand rule defines a positive torque. ADAMS/View assumes that the z-axes of the I and J markers remain aligned at all times.

The following linear constitutive equation describes the torque applied at the first body:

torque = -CT*da/dt - KT*(a-ANGLE) + TORQUE



ADAMS/Solver automatically computes the terms da/dt and a. The term a is the angle between the x axes of the I and the J markers. ADAMS/Solver takes into account the total number of complete turns.

Figure 77. Rotational Displacement About Two Markers

You can specify the damping and stiffness values as coefficients or use a spline to define the relationship of damping to velocity or stiffness to displacement. You can also set the stiffness value to 0 to create a pure damper or set the damping values to 0 to create a pure spring. For more information on defining splines, see Creating Data Element Splines on page 332.

You can also set the rotation angle of the torsion spring when it is in its preload state and any preload forces on the spring. By default, ADAMS/View uses the rotation angle of the torsion spring when you create it as its preload angle.

Caution: By its definition a beam is asymmetric. Holding the J marker fixed and deflecting the I marker produces different results than holding the I marker fixed and deflecting the J marker by the same amount. This asymmetry occurs because the coordinate system frame that the deflection of the beam is measured in moves with the J marker.

Yj

a

Yi

Xi

Xj

Zi

Zj



Creating a Torsion Spring

To create a torsion spring:

1 From the Create Forces palette or tool stack, select the Torsion Spring tool .



■ 1 location




■ Normal to Grid - Lets you orient the force along the x-, y-, and z-axes of the current working grid, if it is displayed, or along the x-, y-, and z-axes of the screen.

■ Pick Feature - Lets you orient the force along a direction vector on a feature in your model, such as the face of a part. The direction vector you select defines the z-axis for the force; ADAMS/View automatically calculates the x- and y-axes.

■ If desired, enter torsional stiffness (KT) and torsional damping (CT) coefficients.

3 Click the bodies unless ADAMS/View is automatically selecting them (1 location method).


5 If you selected to orient the force along a direction vector using a feature, move the cursor around in your model to display an arrow that shows the direction along a feature where you want the force oriented. Click when the direction vector shows the correct z-axis orientation.



Modifying a Torsion Spring

After you’ve created a torsion spring, you can modify:

■ Parts between which the torque acts.

■ Stiffness and damping values, including specifying a spline that defines the relationship of stiffness to displacement. For more information on defining splines, see Creating Data Element Splines on page 332.

■ Preload values.

■ Whether or not force graphics appear. You can select to display force graphics for either part to which the force is applied. Force graphics display an arrow in the direction of the force. The length of the arrow is proportional to the magnitude of the force. By default, ADAMS/View turns on force graphics for the action body. For information on setting preferences for force graphics, see Setting Up Force Graphics on page 201 of the guide, Simulating Models in ADAMS/View.

To modify a torsion spring:

1 Display the Modify a Torsion Spring dialog box as explained in Accessing Modify Dialog Boxes on page 420.

2 In the Action Body and Reaction Body text boxes, change the parts to which the torsion spring is applied, if desired.

3 Enter values for stiffness and damping as explained in Table 24 on page 242, and then select OK.



Table 24. Options for Torsion Spring


Stiffness Select one of the following:■ Stiffness Coefficient and enter a stiffness

coefficient for the torsion spring.

■ No Stiffness to turn off all spring forces and create a pure damping force.

■ Spline: F=f(defo) and enter a spline that defines the relationship of stiffness to rotational deformation (radians). (For information on defining splines, see Creating Data Element Splines on page 332.)


Damping Select one of the following:■ Damping Coefficient and enter a viscous damping

coefficient for the torsion spring.

■ No Damping to turn off all damping forces to create a pure spring force.

■ Spline: F=f(velo) and enter a spline that defines the relationship of force to angular velocity (radians per second). (For information on defining splines, see Creating Data Element Splines on page 332.)




Preload force and angle of spring

Do the following:■ In the Preload text box, enter the preload force

for the torsion spring. Preload force is the force of the torsion spring in its preload position.

■ Select one of the following:

■ Default Angle to set the rotation angle of the spring when you created it as its preload position.

■ Angle at Preload and enter the angle of the spring at its preload position.

Set graphics From the Torque Display option menu, select whether you want to display force graphics for one of the parts, both, or none.

Table 24. Options for Torsion Spring (continued)




Adding a Massless Beam

You can create a massless beam with a uniform cross-section. You enter values of the beam’s physical properties, and ADAMS/Solver, the analysis engine, calculates the matrix entries defining the forces that the beam produces. The beam transmits forces and torques between the two parts in accordance with Timoshenko beam theory.

The following sections explain more about beams and how to create and edit them.

■ About Beams, 244

■ Constitutive Equations for Beams, 246

■ Creating a Beam, 248

■ Modifying a Beam, 249

About Beams

A beam creates a linear translational and rotational force between two locations that define the endpoints of the beam. It creates coordinate system markers at each endpoint. The marker on the action body, the first part you select, is the I marker. The marker on the reaction body, the second part you select, is the J marker. The forces the beam produces are linearly dependent on the relative displacements and velocities of the markers at the beam’ s endpoints.

Figure 78 shows the two markers (I and J) that define the endpoints of the beam and indicates the twelve forces (s1 to s12) it produces.



Figure 78. Massless Beam

The x-axis of the J marker defines the centroidal axis of the beam. The y-axis and z-axis of the J marker are the principal axes of the cross section. They are perpendicular to the x-axis and to each other. When the beam is in an undeflected position, the I marker has the same angular orientation as the J marker, and the I marker lies on the x-axis of the J marker. ADAMS/View applies the following forces in response to the translational and the rotational deflections of the I marker with respect to the J marker:

■ Axial forces (s1 and s7)

■ Bending moments about the y-axis and z-axis (s5, s6, s11, and s12)

■ Twisting moments about the x-axis (s4 and s10)

■ Shear forces (s2, s3, s8, and s9)

Note: You can use a field element instead of a beam to define a beam with characteristics unlike those that the beam assumes. For example, a field element can define a beam with a non-uniform cross section or a beam with nonlinear material characteristics. (For more information, see Adding a Field Element on page 255.)

z

x

J

s3s6s1

s4

y

s5

s2

y

x

z

I

s8

s11

s10

s12

s7

s9

L



Constitutive Equations for Beams

The following constitutive equations define how ADAMS/Solver uses the data for a linear field to apply a force and a torque to the I marker on the action body. The force and torque it applies depends on the displacement and velocity of the I marker relative to the J marker on the reaction body. The constitutive equations are analogous to those in the finite element method.

where:

■ Fx, Fy, and Fz are the measure numbers of the translational force components in the coordinate system of the J marker.

■ x, y, and z are the translational displacements of the I marker with respect to the J marker measured in the coordinate system of the J marker.

■ Vx, Vy, and Vz are the time derivatives of x, y, and z, respectively.

■ Tx, Ty, and Tz are the rotational force components in the coordinate system of the J marker.

Fx

Fy

Fz

Tx

Ty

Tz

K11 0 0 0 0 0

0 K22 0 0 0 K26

0 0 K33 0 K35 0

0 0 0 K44 0 0

0 0 K53 0 K55 0

0 K62 0 0 0 K66

x L–

y

z

a

b

c

–=

C11 C21 C31 C41 C51 C61C21 C22 C32 C42 C52 C62C31 C32 C33 C43 C53 C63C41 C42 C43 C44 C54 C64C51 C52 C53 C54 C55 C65C61 C62 C63 C64 C65 C66

Vx

Vy

Vz

ωx

ωy

ωz

–



■ a, b, and c are the relative rotational displacements of the I marker with respect to the J marker as expressed in the x-, y-, and z-axis, respectively, of the J marker.


Note that both matrixes, Cij and Kij, are symmetric, that is, Cij=Cji and Kij=Kji. You define the twenty-one unique damping coefficients when you modify the beam.

ADAMS/Solver defines each Kij in the following way:

K11 = E A / L

K22 = 12 E Izz /[L3 (1+Py)]

K26

= -6 E Izz /[L2 (1+Py)]

K33

= 12 E Iyy /[L3 (1+Pz)]

K35

= 6 E Iyy /[L2 (1+Pz)]

K44

= G Ixx / L

K55

= (4+Pz) E Iyy /[L (1+Pz)]

K66

= (4+Py) E Izz /[L (1+Py)]

where:

■ E = Young’s modulus of elasticity for the beam material.

■ A = Uniform area of the beam cross section.

■ L = Undeformed length of the beam along the x-axis.

■ Py = 12 E Izz ASY/(G A L2)

■ Pz = 12 E Iyy ASZ/(G A L2)

■ ASY = Correction factor (shear area ratio) for shear deflection in the y direction for Timoshenko beams.

■ ASZ = Shear area ratio for shear deflection in the z direction for Timoshenko beams.



ADAMS/Solver applies an equilibrating force and torque at the J marker on the reaction body, as defined by the following equations:

Fj = - Fi

Tj = - Ti - L Fi

L is the instantaneous displacement vector from the J marker to the I marker. While the force at the J marker is equal and opposite to the force at the I marker, the torque is usually not equal and opposite, because of the force transfer.

Creating a Beam

To create a beam:

1 From the Create Forces palette or tool stack, select the Massless Beam tool .

2 Select a location for the beam on the first part. This is the action body.

3 Select a location for the beam on the second part. This is the reaction body.

4 Select the direction in the upward (y) direction for the cross-section geometry.

×



Modifying a Beam

After you’ve created a beam, you can modify the following:

■ Coordinate systems between which the beam acts.

■ Stiffness and damping values.

■ Material properties of the beam, such as its length and area.

To modify a beam:

1 Display the Force Modify Element Like Beam dialog box as explained in Accessing Modify Dialog Boxes on page 420.

2 Change the name of the beam, if desired, and assign a unique ID number to the beam. The ID is an integer used to identify the element in the ADAMS/Solver dataset (.adm) file. You only need to specify an ID number if you are exporting the model to an ADAMS/Solver dataset, and you want to control the numbering scheme used in the file.

Enter a positive integer or enter 0 to have ADAMS set the ID number for you.

3 Enter any comments about the beam that might help you manage and identify the beam. You can enter any alphanumeric characters. The comments that you create appear in the information window when you select to display information about the object, in the ADAMS/View log file, and in a command or dataset file when you export your model to these types of files.

4 Enter values for the beam properties as explained in Table 25 on page 250, and then select OK.



Table 25. Options for Beams


Area moments of inertia

Enter the following:■ In the Ixx text box, enter the torsional constant.

The torsional constant is sometimes referred to as the torsional shape factor or torsional stiffness coefficient. It is expressed as unit length to the fourth power. For a solid circular section, Ixx is identical to the polar moment of inertia J=(πr4/2). For thin-walled sections, open sections, and non-circular sections, you should consult a handbook.

■ In the Iyy and Izz text boxes, enter the area moments of inertia about the neutral axes of the beam cross sectional areas (y-y and z-z). These are sometimes referred to as the second moment of area about a given axis. They are expressed as unit length to the fourth power. For a solid circular section, Iyy=Izz=(πr4/4). For thin-walled sections, open sections, and non-circular sections, you should consult a handbook.

Area of the beam cross section

In the Area of Cross Section text box, enter the uniform area of the beam cross-section geometry. The centroidal axis must be orthogonal to this cross section.



Shear area ratio In the Y Shear Area Ratio and Z Shear Area Ratio text boxes, specify the correction factor (the shear area ratio) for shear deflection in the y and z direction for Timoshenko beams. If you want to neglect the deflection due to shear, enter zero in the text boxes.■ For the y direction:

where:■ Qy is the first moment of cross-sectional area

to be sheared by a force in the z direction.

■ lz is the cross section dimension in the z direction.

■ For the z direction:

where:■ Qz is the first moment of cross-sectional area

to be sheared by a force in the y direction.

■ ly is the cross section dimension in the y direction.

Common values for shear area ratio based on the type of cross section are:

■ Solid rectangular - 6/5

■ Solid circular - 10/9

■ Thin wall hollow circular - 2

Table 25. Options for Beams (continued)


YA

I2----

Qy

lz------

2Ad

A∫=

y

ZA

I2----

Qz

ly------

2Ad

A∫=

z



Shear area ratio (continued)

Note: The K1 and K2 terms that are used by MSC/NASTRAN for defining the beam properties using PBEAM are the inverse of the y shear and z shear values that ADAMS/View uses.

Young’s and shear modulus of elasticity

In the Young’s Modulus and Shear Modulus text box, enter Young’s and shear modulus of elasticity for the beam material.

Length of beam Enter the undeformed length of the beam along the x axis of the J marker on the reaction body.





Damping ratio or damping matrix

Select one of the following from the option menu:■ Damping Ratio and enter a damping value to

establish a ratio for calculating the structural damping matrix for the beam. To obtain the damping matrix, ADAMS/Solver multiplies the stiffness matrix by the value you enter for damping ratio.

■ Damping Matrix and enter a a six-by-six structural damping matrix for the beam. Because this matrix is symmetric, you only need to specify one-half of the matrix. The following matrix shows the values to input:

Enter the elements by columns from top to bottom, then from left to right. The damping matrix defaults to a matrix with thirty-six zero entries; that is, r1 through r21 each default to zero.

The damping matrix should be positive semidefinite. This ensures that damping does not feed energy into the model. ADAMS/Solver does not warn you if the matrix is not positive semidefinite.



r01

r02 r07

r03 r08 r12

r04 r09 r13 r16

r05 r10 r14 r17 r19

r06 r11 r15 r18 r20 r21



Markers that define the beam

Specify the two markers between which to define a beam. The I marker is on the action body and the J marker is on the reaction body. The J marker establishes the direction of the force components.

By definition, the beam lies along the positive x-axis of the J marker. Therefore, the I marker must have a positive x displacement with respect to the J marker when viewed from the J marker. In its undeformed configuration, the orientation of the I and the J markers must be the same.

When the x -axes of the markers defining a beam are not collinear, the beam deflection and, consequently, the force corresponding to this deflection are calculated. To minimize the effect of such misalignments, perform a static equilibrium at the start of the simulation.

When the beam element angular deflections are small, the stiffness matrix provides a meaningful description of the beam behavior. When the angular deflections are large, they are not commutative; so the stiffness matrix that produces the translational and rotational force components may not correctly describe the beam behavior. ADAMS/Solver issues a warning message if the beam translational displacements exceed 10 percent of the undeformed length.





Adding a Field Element

A field element applies a translational and rotational action-reaction force between two locations. ADAMS/View creates coordinate system markers at each location. The marker on the first location you specify is called the I marker. The marker on the second location you specify is called the J marker. ADAMS/View applies the component translational and rotational forces for a field to the I marker and imposes reaction forces on the J marker.

The field element can apply either linear or nonlinear force, depending on the values that you specify after you create the field.

■ To specify a linear field, enter values that define a six-by-six stiffness matrix, translational and rotational preload values, and a six-by-six damping matrix. The stiffness and damping matrixes must be positive semidefinite, but need not be symmetric. You can also specify a damping ratio instead of specifying a damping matrix.

■ To specify a nonlinear field, use the user-written subroutine FIESUB to define the three force components and three torque components and to enter values to pass to FIESUB.

The following sections explain more about field elements and how to create and edit them.

■ Creating a Field Element, 258

■ Constitutive Equations for Field Element, 256

■ Creating a Field Element, 258

■ Modifying a Field Element, 259

■ Cautions for Using Field Elements, 264



Constitutive Equations for Field Element

The following constitutive equations define how ADAMS/Solver uses the data for a linear field to apply a force and a torque to the I marker depending on the displacement and velocity of the I marker relative to the J marker.

For a nonlinear field, the following constitutive equations are defined in the FIESUB subroutine:

Fx=f1(x,y,z,a,b,c,Vx,Vy,Vz, , , )

Fy=f2(x,y,z,a,b,c,Vx,Vy,Vz, , , )

Fz=f3(x,y,z,a,b,c,Vx,Vy,Vz, , , )

Tx=f4(x,y,z,a,b,c,Vx,Vy,Vz, , , )

Ty=f5(x,y,z,a,b,c,Vx,Vy,Vz, , , )

Tz=f6(x,y,z,a,b,c,Vx,Vy,Vz, , , )

Fx

Fy

Fz

Tx

Ty

Tz

K11 K12 K13 K14 K15 K16

K21 K22 K23 K24 K25 K26

K31 K32 K33 K34 K35 K36

K41 K42 K43 K44 K45 K46

K51 K52 K53 K54 K55 K56

K61 K62 K63 K64 K65 K66

x x0–

y y0–

z z0–

a a0–

b b0–

c c0–

–=

C11 C12 C13 C14 C15 C16

C21 C22 C23 C24 C25 C26

C31 C32 C33 C34 C35 C36

C41 C42 C43 C44 C45 C46

C51 C52 C53 C54 C55 C56

C61 C62 C63 C64 C65 C66

Vx

Vy

Vz

ωx

ωy

ωz

–

F1

F2

F3

T1

T2

T3

+

a· b· c·

a· b· c·

a· b· c·

a· b· c·

a· b· c·

a· b· c·



ADAMS/Solver applies the defined forces and torques at the I marker. In the linear and nonlinear equations:

■ Fx, Fy, and Fz are the three translational force measure numbers.

■ Tx, Ty, and Tz are the three rotational force measure numbers associated with unit vectors directed along the x-, y-, and z-axes of the J marker.

■ K is the stiffness matrix.

■ x0, y0, z0, a0, b0, and c0 are the free lengths.

■ x, y, z, a, b, and c are the translational and the rotational displacements of the I marker with respect to the J marker expressed in the coordinate system of the J marker.

■ Vx, Vy, and Vz are the scalar time derivatives of x, y, and z, respectively.


■ C is the damping matrix.

■ F1, F2, F3, T1, T2, and T3 are the translational and rotational pre-tensions.

ADAMS/Solver computes all variables and time derivatives in the J marker coordinate system.

ADAMS/Solver applies an equilibrating force and torque at the J marker, as defined by the following equations:

Fj = - Fi

Tj = - Ti - L Fi

L is the instantaneous displacement vector from the J marker to the I marker. While the force at the J marker is equal and opposite to the force at the I marker, the torque is usually not equal and opposite, because of the force transfer.

×



Creating a Field Element

When you create a field element, you define the location of the force element. ADAMS/View creates I and J markers defining the location and direction of the field. To define other properties of the field element, such as its damping values, you must modify the field.

To create a field:

1 From the Create Forces palette or tool stack, select the Field Element tool .



■ 1 Location

■ 2 Bodies - 1 Location

■ 2 Bodies - 2 Locations




■ Pick Feature - Lets you orient the force along a direction vector on a feature in your model, such as the face of a part. The direction vector you select defines the z-axis for the force; ADAMS/View calculates the x- and y-axes automatically.

3 Click the bodies unless ADAMS/View is automatically selecting them.


5 If you selected to orient the force along a direction vector on a feature, move the cursor around in your model to display an arrow that shows the direction along a feature where you want the force oriented. When the direction vector shows the correct z-axis orientation, click.



Modifying a Field Element

After you’ve created a field element, you can modify it to define a linear or nonlinear force.

To modify a field element:

1 Display the Force Modify Element Like Field dialog box as explained in Accessing Modify Dialog Boxes on page 420.

2 Change the name of the field element, if desired, and assign a unique ID number to the field. The ID is an integer used to identify the element in the ADAMS/Solver dataset (.adm) file. You only need to specify an ID number if you are exporting the model to an ADAMS/Solver dataset, and you want to control the numbering scheme used in the file.


3 Enter any comments about the field that might help you manage and identify the field. You can enter any alphanumeric characters. The comments that you create appear in the information window when you select to display information about the object, in the ADAMS/View log file, and in a command or dataset file when you export your model to these types of files.

4 Enter values for the field properties as explained in Table 26 on page 260, and then select OK.



Table 26. Options for Modifying Field Elements


Markers that define the field

In the I Marker Name and J Marker Name text boxes, specify the two markers between which the force and torque are to be exerted. ADAMS/View applies the component translational and rotational forces for a field to the I marker and imposes reaction forces on the J marker.

Translational and rotational preload of field

Enter the preload translational and rotational force for the field in the Preload text boxes. ■ Translation at Preload to define three reference

lengths. This is the nominal (x0, y0, z0) position of the I marker with respect to the J marker, resolved in the J marker coordinate system.

■ Rotation at Preload to define the reference rotational displacement of the axes of the I marker with respect to the J marker, resolved in the J marker axes (a0, b0, and c0) (specified in radians).

If the reference force is zero, then the preload is the same as the free length. Entering preload values is optional and defaults to a six zero entry.



Force preload or parameters to a user-written subroutine

Select one of the following:■ Define Using Standard Values and enter values for

the text boxes that appear in the dialog box as explained in the next cells of this table.

■ Define Using Subroutine and enter parameters to be passed to the user-written subroutine FIESUB to define a nonlinear field. Enter up to 30 values (r1[,...,r30]) that ADAMS/View is to pass to FIESUB. See the Using ADAMS/Solver Subroutines guide for more on the FIESUB subroutine and nonlinear fields.

Force and torque preload

In the Force Preload and Torque Preload text boxes, define three preload force components and three preload torque components transferred by the field element when the I and J markers are separated/misaligned by the values specified in the Translation at Preload and Rotation at Preload text boxes.

The terms are the force components along the x-, y-, and z-axis of the J marker and the torque components about the x-, y-, and z-axis of the J marker, respectively. Entering values for Force Preload and Torque Preload is optional and defaults to six zero entries.

Table 26. Options for Modifying Field Elements (continued)




Stiffness matrix In the Stiffness Matrix text box, define a six-by-six matrix of stiffness coefficients. The following matrix shows the values to input.

Enter the elements by columns from top to bottom, then from left to right. The units for the translational and rotational components of stiffness matrix should be force per unit displacement and torque per radian, respectively.

Tip: A finite element analysis program can give you the values for the stiffness matrix.



r1 r7 r13 r19 r25 r31

r2 r8 r14 r20 r26 r32

r3 r9 r15 r21 r27 r33

r4 r10 r16 r22 r28 r34

r5 r11 r17 r23 r29 r35

r6 r12 r18 r24 r30 r36



Damping coefficients

Enter either a matrix of damping terms or a damping ratio if you want to include damping coefficients in the calculation of the field forces as explained below. The damping matrix defaults to a matrix with thirty-six zero entries. ■ To define a six-by-six matrix of viscous

damping coefficients, select Matrix of Damping Terms and enter the elements. The following matrix shows the values to input.

Enter the elements by columns from top to bottom, then from left to right. The units for the translational and rotational components should be force-time per unit displacement and torque-time per radian, respectively.

■ To enter a damping ratio that defines the ratio of the damping matrix to the stiffness matrix, select Damping Ratio and enter the value. If you enter a damping ratio, ADAMS/Solver multiplies the stiffness matrix by the ratio to obtain the damping matrix. Do not enter a ratio without also entering a stiffness matrix.

Tip: A finite element analysis program can give you the values for the damping matrix.



r1 r7 r13 r19 r25 r31

r2 r8 r14 r20 r26 r32

r3 r9 r15 r21 r27 r33

r4 r10 r16 r22 r28 r34

r5 r11 r17 r23 r29 r35

r6 r12 r18 r24 r30 r36



Cautions for Using Field Elements

■ For the constitutive equations of a field element to be accurate, at least two of the rotations (a, b, c) must be small. That is, two of the three values must remain smaller than 10 degrees. In addition, if a becomes greater than 90 degrees, b becomes erratic. If b becomes greater than 90 degrees, a becomes erratic. Only c can become greater than 90 degrees without causing convergence problems. For these reasons, it is best to define your field such that angles a and b (not a and c and not b and c) remain small.

■ The three rotational displacements (a, b, and c) that define the field are not Euler angles. They are the projected angles of the I marker with respect to the J marker. ADAMS/Solver measures them about the x-, y-, and z-axis of the J marker.

■ The K and C matrixes must be positive semidefinite. In other words:

xt K x 0 for all displacements x

yt C y 0 for all velocities y

If this is not true, the stiffness matrix of the field may be removing energy from the model. Similarly, the damping matrix may be adding energy to the system. Both of these situations are uncommon. ADAMS/Solver does not warn you if the C matrix, K matrix, or both, are not positive semidefinite. While ADAMS/Solver does not require that these matrixes be symmetric, that is most realistic.

≥≥



Working with Modal Forces in ADAMS/ViewA modal force, or MFORCE, allows you to distribute a force to one or more, or all nodes of a flexible body. The magnitude of the force can vary in time or position, and can even be made dependent on a state variable. Examples of modal force applications are pressures on journal bearings, simulating magnetically induced fields, or the modeling of airfoil flutter. Modal forces are a special class of forces called distributed loads that can only be applied to flexible bodies.

For a detailed overview of distributed loads and a tutorial that steps you through an example of adding modal forces to your model, see Modeling Distributed Loads and Predeformed Flexible Bodies on page 95 in the guide, Using ADAMS/Flex.

Defining Modal Forces

ADAMS/View provides two options for defining MFORCES on flexible bodies. Both options require additional work outside of ADAMS/View to complete the definition and simulation of modal forces.

■ Reference and scale a load case defined in the flexible body’s modal load matrix. This option can only be used in ADAMS/View on flexible bodies that have been built with modal neutral file (MNF) that contains modal load case information. For more information on flexible bodies, their modal load matrix, and how to generate modal load case information in a modal neutral file, see Creating Load Case Files on page 175 in the guide, Using ADAMS/Flex.

■ Specify modal forces with a user-defined subroutine. This option provides much more capability in defining modal forces.To take advantage of this option, however, you need to develop a MFORSUB routine that is built into the ADAMS/Solver. For more information, see the guide, Using ADAMS/Solver Subroutines.

More than one modal forces can be defined on a flexible body. For each modal force defined on a flexible body a modal force icon appears at its local part reference frame. You can transfer modal forces from one flexible body to another.



Creating a Modal Force

To create a modal force:

1 From the Main toolbox, from the Create Forces tool stack, select the Modal Force

tool .

The Create Modal Force dialog box appears.

2 In the Create Modal Force dialog box, specify the following:

Table 27. Options in Create Modal Force Dialog Box


Assign a name to the MFORCE

In the Force Name text box, enter the name of the modal force to be created. ADAMS/View automatically assigns a default name of MFORCE followed by an underscore and a number to make the name unique (for example, MFORCE_1).

Specify the flexible body to which the MFORCE is applied

In the Flexible Body text box, enter the name of the flexible body. To select a flexible body or create a new body, right-click the text box, and then select the appropriate command.



Apply the reaction of the modal force resultant to a part

If desired, in the Reaction Part text box, enter the name of an existing part. If you enter a part name, ADAMS/View automatically creates a floating marker associated with this part when it creates the MFORCE. ADAMS/View keeps the marker coincident with the flexible body analysis coordinate system during the simulation. Therefore, the need for the point of reaction to be a floating marker.

In addition, because floating markers cannot be defined on flexible bodies, the reaction part is restricted to rigid bodies only.

Tip: You can use the Info command to see the floating marker that ADAMS/View creates when you reference a reaction part.

Table 27. Options in Create Modal Force Dialog Box (continued)




3 If you select to specify a flexible body with modal load case information, you also specify:

■ Load Case - Lets you select a modal load case label from a list. The list of modal load case labels is generated from the MNF.

■ Scale Function - Let’s you specify an expression for the scale factor to be applied to the modal load case.

4 Select OK.

Select how you want to define the modal force.

Select the following from the Define Using option menu:

■ Function - Lets you select the modal load case and scale function of the MFORCE. Note that you cannot select Function when defining an MFORCE on a flexible body that does not contain any modal load case information in its corresponding MNF.

■ Subroutine - Lets you specify one or more user parameters to be passed to the user-defined subroutine, MFOSUB, and lets you set an unique identification number for this particular modal force.

To use Subroutine, you need to build a version of the ADAMS/Solver that contains your version of the MFOSUB routine that quantifies the modal force. For more information, see the guide, Using ADAMS/Solver Subroutines.

Table 27. Options in Create Modal Force Dialog Box (continued)




Modifying a Modal Force

You can modify an existing MFORCE in the following ways:

■ The flexible body to which the modal forces is applied.

■ The part to which the reaction resultant of the modal force is applied.

■ The definition of the modal force.

To modify a MFORCE:

1 Display the Modify a Force or Modify a Torque dialog box as explained in Accessing Modify Dialog Boxes on page 420.

2 Follow the instructions in Creating a Modal Force on page 266.

3 Select OK.

Copying and Deleting a Modal Force

You can copy and delete MFORCEs just like you copy and delete other objects in ADAMS/View. See Copying Objects on page 421 and Deleting Objects on page 423.

Note: When you copy a MFORCE that has a reaction part specified or as a result, a floating marker referenced, ADAMS/View also creates a new floating marker.

In addition, when you delete a MFORCE that has a reaction part specified, ADAMS/View does not delete its referenced floating marker.



Viewing Modal Preloads of Flexible BodiesA special form of a modal load in a flexible body is a modal preload. Since modal preloads are an integral property of the flexible body, you do not have the ability to modify these loads in ADAMS/View. You can, however, inspect the values of these preloads for each mode. In ADAMS/View, there are two ways to review the modal preloads of a flexible body.

For a detailed overview of modal preloads and a tutorial that steps you through an example of modeling preloads, see Modeling Distributed Loads and Predeformed Flexible Bodies on page 95 in the guide, Using ADAMS/Flex.

To review the modal preloads using the Flexible Body Modify dialog box:

1 Double-click the flexible body to display the Flexible Body Modify dialog box.

2 From the Flexible Body Modify dialog box, select Modal ICs.

The Modify Modal ICs... dialog box appears. Preloads for the flexible body appear in the last column.

3 Review the preloads and select Close.

To obtain a listing of the preloads using the Info command:

1 Display information on the flexible body as explained in Viewing Object Information on page 174 in the guide, Learning ADAMS/View Basics.

2 In the information window, select Verbose, and then select Apply.

The modal preload values appear in the last column of the modal frequency table.

8 Working with Contacts

OverviewUsing contacts, you can go beyond just modeling how parts meet at points and model how points on parts follow curves or model how curves on one part follow curves on another part. In addition, you can model how solid bodies react when they come in contact with one another when the model is in motion.

The following sections explain more about contacts.

■ Working with Cams, 272

■ Working with Contact Forces, 290

■ Working with Forced-Based Contacts, 302

For a listing of the DOF that the contacts allow, see Table 14 on page 130.


Working with Contacts272

Working with CamsADAMS/View provides you with two types of cams: pin-in-slot and curve-on-curve. The next sections explain the two types of cams and how to create and modify them.

■ Pin-in-Slot Cams, 272

■ Curve-on-Curve Cams, 274

■ Creating a Cam, 275

■ Tips on Creating Cams, 276

■ Modifying a Cam, 278

Pin-in-Slot Cams

The pin-in-slot cam defines a point-to-curve constraint that restricts a fixed point defined on one part to lie on a curve defined on a second part. The first part is free to roll and slide on the curve that is fixed to a second part. The curve on the second part can be planar or spatial or open or closed. The first part cannot lift off the second part; it must always lie on the curve. A pin-in-slot contact removes two translational DOF from your model.

When you specify the location of the pin-in-slot on the first part, ADAMS/View creates a coordinate system marker at that location. The marker is called the I marker. The I marker can only translate in one direction relative to the curve. The I marker, however, is free to rotate in all three directions.

You can use the pin-in-slot cam to model a pin-in-slot mechanism (shown in Figure 79) or a simple cam follower mechanism (shown in Figure 80) where a lever arm is articulated by the profile of a revolving cam.

When modeling a pin-in-slot mechanism, the pin-in-slot contact keeps the center of the pin in the center of the slot, while allowing it to move freely along the slot and rotate in the slot.



Figure 79. Pin-in-slot Reciprocating Mechanism

Figure 80. Point-Follower Mechanism

Curve

Cam Rigid Body

Follower Rigid Body

Location Point

Cam part

Curve Location point

Follower part

Curve

Location Point

Cam Rigid Body

Follower Rigid Body

Cam part

Curve

Location point

Follower part



Curve-on-Curve Cams

A curve-on-curve cam (shown in Figure 81) restricts a curve defined on the first part to remain in contact with a second curve defined on a second part. The curve-on-curve cam is useful for modeling cams where the point of contact between two parts changes during the motion of the mechanism. The curve-on-curve cam removes three DOF from your model.

An example of a curve-on-curve cam is a valve lifter where a cam lifts a plate-like object. The point of contact between the plate and the cam change depending on the position and shape of the cam.

Figure 81. Curve-on-Curve Cam

The two curves of the cam, which you define by selecting edges in your model, must lie in the same plane. It is possible to initially select curves that are not in the same plane, but ADAMS/Solver moves the parts during simulation to ensure that the two curves are constrained to the same plane of motion with respect to each other. Both curves can be open or closed.

Cam

Followerpart

part



The curves always maintain contact, even when the dynamics of the model might actually lift one curve off the other. You can examine the constraint forces to determine if any lift-off should have occurred. If your results require an accurate simulation of intermittent contact, you should model the contact forces directly using a vector force.

The curve-on-curve cam models only one contact. Therefore, if the curves have contact at more than one point, you need to create a curve-on-curve cam for each contact, each with a initial condition displacement near the appropriate point. For more on initial conditions, see Modifying a Cam on page 278.

Note: Instead of defining a curve by selecting a curve on a part, you can also use a curve element that you create to define the curve. To specify a curve element, you can create geometry for the curve and select that geometry as you create the cam or modify the cam to reference the curve element. For more information, see Creating Data Element Curves on page 322.

Creating a Cam

Before creating a cam, read Tips on Creating Cams on page 276.

To create a pin-in-slot or curve-on-curve cam:

1 From the Joint palette, select the cam joint tool representing the cam that you want to create. Select:

■ to create a pin-in-slot cam.

■ to create a curve-on-curve cam.

2 Select either:

■ For a pin-in-slot cam, select a point on a part that will travel along a curve.

■ For a curve-on-curve cam, select a curve that will travel along a second curve.

3 Select the curve along which the point or first curve will travel. The curve can be closed or open. Note that when you select a closed curve, the Dynamic Model Navigator highlights only a portion of the curve. ADAMS/View will use the entire curve.



Tips on Creating Cams

The following are some tips for creating cams.

■ Specify a curve with a large number of curve points.

When you select a curve, be sure that it contains a sufficiently large number of points to achieve an acceptable fit.

■ Use closed curves whenever possible.

It is generally easier to select a closed curve, if possible. Open curves represent modeling difficulties when the point on the follower part approaches one of the end points of the open curve.

■ Define curves that cover the entire expected range of motion of the cam.

ADAMS/Solver stops a simulation if the contact point moves off the end of an open curve. Therefore, be sure that the curve you define covers the expected range of motion of the contact point.

■ Avoid defining an initial configuration with the initial point of contact near to one of the end points of the curve.

■ Avoid curve-on-curve cams that have more than one contact point.

ADAMS/Solver requires that your model contain a unique contact point during simulation. If there is more than one contact point, ADAMS/Solver may be unable to find the correct contact point or may even jump from one contact point to the next. It also may have difficulties finding the correct solution. One way to ensure that contact points are unique is to specify curve shapes that are convex. Figure 82 shows two curves, the first is convex and the second is nonconvex. Note that for a convex curve, any line segment connecting two arbitrary points on the curve lies in the domain of the curve (it does not intersect the curve). The same is not true for nonconvex curves.



Figure 82. Convex and Nonconvex Curves

■ You can create more than one contact using the same curve.

■ It is easy to over-constrain a model using the curve-to-curve cam. For example, in a cam-follower configuration, the cam should usually be rotating on a cylindrical joint, not a revolute joint. If the follower is held by a translational joint and the cam by a cylindrical joint, the curve-to-curve cam between the follower and cam prevents the cam from translating along the axis of rotation, which is the axis of the cylindrical joint. A revolute joint would add a redundant constraint in that direction.

Convex Curve Nonconvex Curve

Always a single contact Multiple contacts possible

Convex Curve Nonconvex Curve

Always a single contact Multiple contacts possible



Modifying a Cam

After you create a cam, you can change the curve and points used in defining the contact, as well as specify initial conditions for the cam. The next sections explain how to perform these operations:

■ About Cam Initial Conditions, 278

■ Accessing Modify Dialog Boxes, 280

■ Modifying a Cam and Setting Initial Conditions, 282

About Cam Initial Conditions

The initial conditions that you can set include:

■ Pin-in-slot - The initial conditions for a pin-in-slot include:

■ Velocity with which the point (I marker) moves along the curve. You specify the velocity in the coordinate system of the part containing the curve. Therefore, you specify the speed of the I marker from the standpoint of an observer on the part containing the curve. Thus, if the curve, not the I marker, moves globally then the velocity of the I marker is still nonzero.

■ Initial point of contact on the curve. If the point you specify is not exactly on the curve, ADAMS /View uses a point on the curve nearest to the point you specified. By default, you specify the initial point of contact in the coordinate system of the part containing the curve. If another coordinate system is more convenient, you can specify another initial conditions coordinate system marker and enter the initial point in its coordinates.

If you supply an initial point, ADAMS/View assembles the model with the I marker at the specified point on the curve, even if it must override part initial conditions to do so. If you do not supply an initial point, ADAMS/View assumes the initial contact is at the point on the curve closest to the I marker position. ADAMS/View may adjust that contact point to maintain other part or constraint initial conditions.



■ Curve-on-curve cam - The initial conditions for a curve-on-curve cam include:

■ Velocity with which the contact point on either or both curves is moving. You specify the velocity in the coordinate system of the part containing the second curve. If you do not supply an initial velocity, ADAMS/View assumes the initial velocity is zero, but may adjust that velocity to maintain other part or constraint initial conditions.

■ Initial point of contact on either or both curves. If the point you specify is not exactly on the curve, ADAMS/View uses a point on the curve nearest to the point you specify. By default, you specify the initial point of contact in the coordinate system of the part containing the curve. If another coordinate system is more convenient, you can specify another initial conditions coordinate system marker and enter the initial point in its coordinates.

If you supply an initial point, ADAMS/View assembles the model with the marker at the specified point on the curve, even if it must override part initial conditions to do so. If you do not supply an initial point, ADAMS/View assumes the initial contact is at the point on the curve closest to the first curve (I curve). ADAMS/View may adjust that con-tact point to maintain other part or constraint initial conditions.

The initial conditions are only active during an assemble model operation, which ADAMS/View runs before it runs a simulation of your model.

You can also leave some or all of the initial conditions unset. Leaving an initial condition unset lets ADAMS/View calculate the initial conditions of the cam during an assemble model operation depending on the other forces and constraints acting on the cam. Note that it is not the same as setting an initial condition to zero. Setting an initial condition to zero means that the cam will not be moving in the specified direction or from a specified point when the simulation starts, regardless of any forces and constraints acting upon it. For a kinematic simulation, the initial conditions are redundant. Therefore, for a model with zero DOF, you should always leave the initial conditions unset.



Accessing Modify Dialog Boxes

To change the basic properties and set initial conditions for a pin-in-slot or curve-on-curve, you use the Constraint Modify Higher Pair Contact Point Curve dialog box or the Constraint Modify Higher Pair Contact Curve Curve dialog box, respectively, shown in Figures 83 and 84. Follow the instructions in Accessing Modify Dialog Boxes on page 420 to display the appropriate cam modify dialog box and follow the instructions in the next section to modify basic properties and set initial conditions using the dialog box.

Note: You can also modify joint properties using the Table Editor. For more information on using the Table Editor, see Editing Objects Using the Table Editor on page 401.



Figure 83. Constraint Modify Higher Pair Contact Point Curve Dialog Box

Figure 84. Constraint Modify Higher Pair Contact Curve Curve Dialog Box

Set initial conditions

Change basicproperties

Set initial conditions

Change basicproperties



Modifying a Cam and Setting Initial Conditions

To modify a cam and set initial conditions:

1 Display the appropriate cam modify dialog box as explained in Accessing Modify Dialog Boxes on page 280.

2 Change the name of the cam, if desired, and assign a unique ID number to the cam. The ID is an integer used to identify the element in the ADAMS/Solver dataset (.adm) file. You only need to specify an ID if you are exporting the model to an ADAMS/Solver dataset, and you want to control the numbering scheme used in the file.


3 In the Comments text box, add any comments about the cam that you want to enter to help you manage and identify the cam. You can enter any alphanumeric characters. The comments that you create appear in the information window when you select to display information about the cam, in the ADAMS/View log file, and in a command or dataset file when you export your model to these types of files.

4 Set the basic properties as explained in Table 28 on page 283.

5 Set the initial conditions as explained in Table 29 on page 287, and then select OK. For more on initial conditions, see About Cam Initial Conditions on page 278.



Table 28. Options for Cam Basic Properties


Pin-in-slot ■ Curve Name - Curve that defines the shape on which the point can move. You can enter a curve on a part or a curve element. For more information on curve elements, see Creating Data Element Curves on page 322.

■ I Marker Name - Point that moves along the curve.

■ J Floating Marker Name - Coordinate system marker that is a floating marker. ADAMS/Solver positions the origin of the floating marker at the instantaneous point of contact on the curve. It orients the marker so that its x-axis is tangent to the curve at the contact point, its y-axis points outward from the curve’s center of curvature at the contact point, and its z-axis is along the binormal at the contact point.

Figure 85. Geometric Representation of Floating Marker Orientation

y (normal)

z (binormal)

j j

j

Center ofCurvature

x (ta

ngen

t)

J floating marker

Curve



Pin-in-slot (continued)

■ Ref Marker Name - Coordinate system marker that is fixed on the part containing the curve on which the point must move. ADAMS/Solver uses the reference marker to associate the shape defined by the curve to the part on which the reference marker lies. The curve coordinates are, therefore, specified in the coordinate system of the reference marker.

Table 28. Options for Cam Basic Properties (continued)




Curve-curve

■ I Curve Name - Curve that defines the shape of the curve that moves along the second curve (J curve). You can enter a curve on a part or a curve element. For more information on curve elements, see Creating Data Element Curves on page 322.

■ J Curve Name - Curve that defines the shape of the curve along which the first curve (I curve) moves. You can enter a curve on a part or a curve element. For more information on curve elements, see Creating Data Element Curves on page 322.

■ I Ref Marker Name - Coordinate system marker that is fixed on the part containing the first curve (I curve). ADAMS/View uses the reference marker to associate the shape defined by the curve to the part on which the reference marker lies. The curve coordinates are, therefore, specified in the coordinate system of the reference marker.

■ J Ref Marker Name - Coordinate system marker that is fixed on the part containing the second curve (J curve). ADAMS/View uses the reference marker to associate the shape defined by the curve to the part on which the reference marker lies. The curve coordinates are, therefore, specified in the coordinate system of the reference marker.





Curve-curve (continued)

■ I Floating Marker Name - Coordinate system marker that is a floating marker. ADAMS/View positions the origin of the floating marker at the instantaneous point of contact on the first curve, which is also the global position of the J floating marker on the second curve. ADAMS/View orients the marker so that its x-axis is along the tangent at the instantaneous contact point, its y-axis is along the instantaneous normal, and its z-axis is along the resultant binormal.

■ J Floating Marker Name - Coordinate system marker that is a floating marker. ADAMS/View positions the origin of the floating marker at the instantaneous point of contact on the second curve, which is also the position of the I floating marker on the first curve. ADAMS/View orients the marker so that its x-axis is along the tangent at the instantaneous contact point, its y-axis is along the instantaneous normal, and its z-axis is along the resultant binormal.





Table 29. Options for Cam Initial Conditions


Pin-in-slot ■ Displacement Ic or No Displacement Ic - Select either:

■ Displacement Ic - Enter the initial point of contact along the curve. If the point you specify is not exactly on the curve, ADAMS/View uses a point on the curve nearest to the point you specify. By default, you specify the initial point of contact in the coordinate system of the part containing the curve or specify it in the coordinate system of the marker you specify for Ic Ref Marker Name.

■ No Displacement Ic - Leaves the initial displacement unset.

■ Velocity Ic or No Velocity Ic - Select either:

■ Velocity Ic - Velocity with which the point (I marker) moves along the curve. You specify the velocity in the coordinate system of the part containing the curve.

■ No I Velocity Ic - Leaves the initial velocity unset.

■ Ic Ref Marker Name - If desired, enter the coordinate system marker with which the initial point of contact on the curve is specified. If you do not enter a marker, ADAMS/View uses the coordinate system of the part containing the curve.



Curve-curve ■ I Displacement Ic or No I Displacement Ic - Select either:

■ I Displacement Ic - Enter the initial point of contact along the first curve (I curve). If the point you specify is not exactly on the curve, ADAMS/View uses a point on the curve nearest to the point you specify. By default, you specify the initial point of contact in the coordinate system of the part containing the curve or specify it in the coordinate system of the marker you specify for I Ic Ref Marker Name.

■ No I Displacement Ic - Leaves the initial displacement unset.

■ J Displacement Ic or No J Displacement Ic - Select either:

■ J Displacement Ic - Enter the initial point of contact along the second curve (J curve). If the point you specify is not exactly on the curve, ADAMS/View uses a point on the curve nearest to the point you specify. By default, you specify the initial point of contact in the coordinate system of the part containing the curve or specify it in the coordinate system of the marker you specify for J Ic Ref Marker Name.

■ No J Displacement Ic - Leaves the initial displacement unset.

Table 29. Options for Cam Initial Conditions (continued)




Curve-curve (continued)

■ I Velocity Ic or No I Velocity Ic - Select either:

■ I Velocity - Enter the initial velocity of the contact point along the first curve (I curve). This is the speed at which the contact point is initially moving relative to the curve. The velocity is negative if the contact point is moving towards the start of the curve, positive if it is moving towards the end of the curve, and zero if it is stationary on the curve.

■ No I Velocity Ic - Leaves the initial velocity unset.

■ J Velocity Ic or No J Velocity Ic - Select either:

■ J Velocity - Enter the initial velocity of the contact point along the second curve (J curve). This is the speed at which the contact point is initially moving relative to the curve. The velocity is negative if the contact point is moving towards the start of the curve, positive if it is moving toward the end of the curve, and zero if it is stationary on the curve.

■ No J Velocity Ic - Leaves the initial velocity unset.

■ I Ic Ref Marker Name - If desired, enter the coordinate system marker with which the initial point of contact (displacement) on the first curve (I curve) is specified. If you do not enter a marker, ADAMS/View uses the coordinate system of the part containing the curve.

■ J Ic Ref Marker Name - If desired, enter the coordinate system marker with which the initial point of contact (displacement) on the second curve (J curve) is specified. If you do not enter a marker, ADAMS/View uses the coordinate system of the part containing the curve.

Table 29. Options for Cam Initial Conditions (continued)




Working with Contact ForcesContacts allow you to model how free-moving bodies interact with one another when they collide during a simulation.

Contacts are grouped into two categroies:

■ Two-dimensional contacts, which include the interaction between planar geometric elements (for example, circle, curve, and point).

■ Three-dimensional contacts, which include the interaction between solid geometry (for example, spheres, cylinders, enclosed shells, extrusions, and revolutions).

Note: You currently cannot model contact between a two-dimensional and a three-dimensional geometry, except for sphere-to-plane contact.

The next sections explain more about using and creating contact forces:

■ Contact Force Algorithms, 290

■ Supported Geometry in Contacts, 291

■ Creating Contact Forces, 293

For more on the theory behind contact forces, see the CONTACT statement in the guide, Using ADAMS/Solver.

Contact Force Algorithms

Contact forces use two distinct normal force algorithms:

■ Restitution-based contact - In this method, ADAMS/Solver, the analysis engine, computes the contact force from a penalty parameter and a coefficient of restitution. The penalty parameter enforces the unilateral constraint, and the coefficient of restitution controls the dissipation of energy at the contact.

■ IMPACT-Function-Based Contact - In this method, ADAMS/Solver computes the contact force from the IMPACT function available in the ADAMS function library. The force is essentially modeled as a nonlinear spring-damper.



Note: Contact defined between planar geometry (for example, circle to curve) must be constrained to lie in the same plane. You usually accomplish this using planar joints or an equivalent set of constraints that enforce the planarity.

Failure to enforce planarity will result in a run-time error when the bodies go out of plane during a simulation.

Supported Geometry in Contacts

ADAMS/View supports three-dimensional contact between the following solid geometry:

■ Sphere

■ Cylinder

■ Frustum

■ Box

■ Generic three-dimensional Parasolid geometry, including extrusion and revolution

■ Shell (enclosed-volume only)

It does not support non-solid, three-dimensional geometries, such as shells that do not represent an enclosed volume.

ADAMS/View supports two-dimensional contact between the following geometry:

■ Arc

■ Circle

■ Curve

■ Point

■ Plane

You can specify your own two-dimensional geometry as curves using the CURSUB user-written subroutine. Refer to Table 30 on page 292 for a listing of the supported geometry combinations.



Table 30. Supported Geometry Combinations

Arc

Circle

Cu

rve

Po

int

Plan

e

Bo

x

Cylin

der

Fru

stum

Ellip

oso

id

Paraso

lidg

eom

etry

Sh

ell (enclo

sedvo

lum

e)

Arc ■ ■ ■ ■ ■

Circle ■ ■ ■ ■ ■

Curve ■ ■ ■ ■ ■

Point ■ ■ ■ ■

Plane■ ■ ■ ■ ■

(Sphere only)

Box ■ ■ ■ ■ ■

Cylinder ■ ■ ■ ■ ■

Frustum ■ ■ ■ ■ ■

Elliposoid ■ ■ ■ ■ ■

Parasolid Geometry

■ ■ ■ ■ ■

Shell (enclosed volume)

■ ■ ■ ■ ■



Creating Contact Forces

To create a contact force:

1 From the Force tool stack or palette, select the Contact Force tool .

The Create Contact dialog box appears.

2 Enter values in the dialog box as explained in Table 31 and select OK.

Tip: You can change the direction of the force on some geometry (for example, circle, curve, and sphere) by selecting the Change Direction tool .

Table 31. Contact Force Options


Define type and geometry

To define the geometry that comes into contact: 1 Set Type to the type of geometry to come into contact.

The text boxes change depending on the type of contact force you selected.

2 In the text boxes, enter the name of the geometry objects. You can also select the object from the screen.

To select geometry from the screen or browse for geometry, right-click the text box, and then select the appropriate command.

Turn on the force display

Select Force Display.

Refine the normal force between two sets of rigid geometries that are in contact

Select Augmented Lagrangian.

When you select Augmented Lagrangian, ADAMS/View uses iterative refinement to ensure that penetration between the geometries is minimal. It also ensures that the normal force magnitude is relatively insensitive to the penalty or stiffness used to model the local material compliance effects.



Define a restitution-based contact

To define the normal force as restitution-based:1 Set Normal Force to Restitution. 2 Enter a penalty value to define the local stiffness

properties between the contacting material. A large penalty value ensures that the penetration of one geometry into another will be small. Large values, however, will cause numerical integration difficulties. A value of 1E6 is appropriate for systems modeled in Kg-mm-sec. For more information on how to specify this value, see the Extended Definition on page 44 for the CONTACT statement in the guide, Using ADAMS/Solver.

3 Enter the coefficient of restitution, which models the energy loss during contact. ❖ A value of zero specifies a perfectly plastic contact

between the two colliding bodies.

❖ A value of one specifies a perfectly elastic contact. There is no energy loss.

The coefficient of restitution is a function of the two materials that are coming into contact. For information on material types versus commonly used values of the coefficient of restitution, see Table 4 on pages 58 through 60 for the CONTACT statement in the guide, Using ADAMS/Solver.

Table 31. Contact Force Options (continued)




Define an impact contact

To define the normal force as based on an impact using the IMPACT function:1 Set Normal Force to Impact. 2 Enter values for the following:

❖ Stiffness - Specifies a material stiffness that is to be used to calculate the normal force for the impact model.In general, the higher the Stiffness, the more rigid or hard the bodies in contact are.

❖ Damping - Enter a value to define the damping properties of the contacting material. A good rule of thumb is that the damping coefficient is about one percent of the stiffness coefficient.

❖ Damping Penetration - Enter a value to define the penetration at which ADAMS/Solver turns on full damping. ADAMS/Solver uses a cubic STEP function to increase the damping coefficient from zero, at zero penetration, to full damping when the penetration reaches the damping penetration. A reasonable value for this parameter is 0.01 mm. For more information, refer to the IMPACT function on page 582 of the guide, Using ADAMS/Solver.

❖ Force Exponent - ADAMS/Solver models normal force as a nonlinear spring-damper. If the damping penetration, above, is the instantaneous penetration between the contacting geometry, ADAMS/Solver calculates the contribution of the material stiffness to the instantaneous normal forces as:

STIFFNESS * (PENALTY)**EXPONENT

For more information, see the IMPACT function on page 582 of the guide, Using ADAMS/Solver.





Model the friction effects at the contact locations using the Coulomb friction model

Select Friction Force.

Note: The friction model models dynamic friction but not stiction.

For more on friction in contacts, see Contact Friction Force Calculation on page 52 for the CONTACT statement in the guide, Using ADAMS/Solver





Example of Using Contact Forces

The following example demonstrates how to create a contact between a cam and follower on a cam valve. In the example, you import an ADAMS/View command file that builds the valve cam model for you. You then create a curve-to-curve contact force to define how the cam and follower come into contact. Finally, you run a simulation of the model to see the forces acting between the cam and follower. The model is shown in Figure 86.

Figure 86. Valve Cam Example

The command file that you’ ll use is in the directory install_dir/aview/examples/user_guide, where install_dir is the directory in which the ADAMS software is installed.

The example is divided into the following sections:

■ Importing the Command File, 298

■ Creating the Contact Force, 299

■ Simulating the Contact Force, 300

Placement ofcontact



Importing the Command File

To import the command file to create the valve cam:

1 Copy the command file valve.cmd to your local directory. It is located in the install_dir/aview/examples/user_guide directory, where install_dir is the directory in which the ADAMS software is installed.

2 Start ADAMS/View and import valve.cmd.

3 Zoom in on the location where the cam and follower meet so that your window looks similar to the one shown in Figure 87.

Figure 87. Zoomed Valve Cam Example

Follower (rod.Circle_1)

Cam (.cam.GCU173)



Creating the Contact Force

Now you’ ll create a contact force between the cam and follower. When modeling contacts, you will typically have several options for how you define the contact. In this example, you could define the contact between three-dimensional solid objects (for example, the cylinder on the follower and the extrusion representing the cam). You will, however, use two-dimensional elements to reduce the time it takes to solve the simulation.

To create the contact:

1 From the Force tool stack, select the Contact Force tool .

The Create Contact dialog box appears.

2 Set Type to Curve to Curve.

3 Right-click the First Curve text box, point to Contact_Curve, and then select Pick.

4 Select the follower geometry on the part Rod (Circle_1). For the location of Circle_1, see Figure 87.

5 Right-click the Second Curve text box, point to Contact_Curve, and then select Pick.

6 Select the cam geometry. It is a BSPLINE with the name .valve.cam.GCU173. For the location of .valve.cam.GCU173, see Figure 87.

ADAMS/View creates a contact force between the cam and follower. Notice that it places a white arrow on each curve to show the direction of the force. Figure 88 on page 300 shows the arrows. For this tutorial, you don’ t need to change direction. If you did need to change it, you’d select the Change Direction tool on the Create or Modify Contact dialog box.



Figure 88. Arrow Indicating Contact-Force Direction

7 Select OK.

Simulating the Contact Force

Now you’ ll simulate the model to see how the cam and follower come into contact now that you’ve added a contact force.

To run a simulation:

1 From the Main toolbox, select the Simulation tool .

2 Set the simulation to have an end time of 1.0 second and 100 output steps.

3 Select the Simulation Start tool .

Notice how the follower lifts off the cam during the simulation.

Arrows indicatingdirection



Viewing the Results of the Simulation

Now you’ ll review the results of the simulation.

To view results of the simulation:

1 From the Review menu, select PostProcessing.

2 Load the animation of the simulation.

3 To divide the window into two viewports, right-click the Page Layout tool

stack , and select the 2 Views - side by side tool.

4 Plot the results of the contact force in the right view.

5 Animate and observe the animation as the cam goes through three cycles. Notice the increased force as the lifter begins movement and the spline when it loads.



Working with Forced-Based ContactsForced-based contacts are special forces that act on parts. These forces are activated when specified part geometry comes into a predefined proximity with each other. ADAMS/Solver, the analysis engine, determines the values for these forces from a set of contact parameters identical to the parameters in the IMPACT function. (For information on the IMPACT function, see the guide, Using the ADAMS/View Function Builder.)

Note: Although we’ve provided force-based contacts, we strongly encourage you to transition to the contacts explained in Working with Contact Forces on page 290. We will discontinue force-based contacts in ADAMS 12.0.

The following sections provide more details about force-based contacts and provide a short tutorial demonstrating how you can create a contact:

■ Types of Force-Based Contacts, 303

■ Creating and Modifying Force-Based Contacts, 305

■ Creating and Modifying Contact Arrays, 308

■ Force-Based Contact Considerations, 311



Types of Force-Based Contacts

Using ADAMS/View, you can combine multiple contact forces to create complex contacts. ADAMS/View provides you with ten types of contact pairs as listed in Table 32. Also, Figure 89 on page 304 shows an example of a revolute joint that has an internal circle-to-circle contact force placed on it.

Table 32. Contact Pairs

Type:First Geometry:

Second Geometry:

Example Application:

Sphere-in-sphere Ellipsoid Ellipsoid Spherical joint with slop and friction

Sphere-to-sphere Ellipsoid Ellipsoid Three-dimensional point-to-point contact

Sphere-plane Ellipsoid Marker (z-axis)

Shell vertices to plane

Circle-plane Circle Marker (z-axis)

Coin or cylinder to plane

Circle-in-circle Circle Circle Revolute joint with slop and friction

Circle-to-circle Circle Circle Two-dimensional point-to-point contact

Point-to-curve Point Curve Knife-edge follower

Circle-to-curve Circle Curve Cam follower

Plane-to-curve Plane Curve Cam follower

Curve-to-curve Curve Curve Cam follower



Figure 89. Revolute Joint with Slop using Internal Circle-circle

Note: Both circle-in-circle and circle-to-circle contacts use the same detection method as sphere-sphere contacts. Circle-circle contacts, however, are used for two-dimensional applications. Therefore, if the circles come into contact when they are out of plane, they behave like spheres.



Creating and Modifying Force-Based Contacts

The next sections explain how to create and modify force-based contacts.

■ Creating Force-Based Contacts, 305

■ Modifying Force-Based Contacts, 307

Creating Force-Based Contacts

Before creating contact forces, you may want to read Force-Based Contact Considerations on page 311 for issues that you may want to look out for.

Tips: You can use the following types of curves for defining two-dimensional curve contacts:

■ Splines that you’ve created from a trace using the Create Trace Spline command on the Review menu. For more information, see Creating a Spline from a Trace on page 75.

■ Curves you’ve converted from polylines using the Spline tool on the Main toolbox. Using this method, you can specify the number of points to distribute in the curve. For more information, see Creating Splines on page 28.

To create a contact force:

1 From the Force tool stack or palette, select the Force-Based Contact tool .

The Create Contact Force dialog box appears.

2 Enter values in the dialog box as explained in Table 33 and select OK.

Tip: You can change the direction of the force on a curve by selecting the Change Direction tool .



Table 33. Contact Force Options


Define type and geometry

To define the geometry that comes into contact: 1 Set Type to the type of geometry to come into

contact. The text boxes change depending on the type of contact force you selected.

2 In the text boxes, enter the name of the geometry objects. You can also select the object from the screen.

To select geometry from the screen or browse for geometry, right-click a text box, and then select the appropriate command.

Note: If the second type you selected is a plane, the second object you select must be a coordinate system marker. The marker’ s z-axis defines the normal vector to plane.

Define the contact forces

Enter a contact array. For information on creating contact arrays, see Creating and Modifying Contact Arrays on page 308.

Set the force display

Set Force Display to the option you want to control the display of force graphics for the contact force.

You can choose not to display force graphics by selecting None, or you could choose to display force graphics on either one of the geometries or on both geometries by selecting First Part, Second Part, or Both.



Modifying Force-Based Contacts

You can modify force-based contacts using the Contact Force Modify Dialog box.

To modify a contact force:

1 Display the Contact Force Modify dialog box as explained in Accessing Modify Dialog Boxes on page 420.

2 Change the options in the dialog box as desired. The options for modifying a contact force are identical to the options for creating a contact force. For more information on the options, see Table 33.

Note: The contact force screen icon is identical to the general force icon.



Creating and Modifying Contact Arrays

Contact arrays define the characteristics of force-based contacts. You specify a contact array for each force-based contact. You can, however, use the same contact array with multiple contact forces.

The options for defining the normal force magnitudes for contact arrays are identical to the parameters in the IMPACT function For information on the IMPACT function, see the guide, Using the ADAMS/View Function Builder.

The following sections describe how to create and modify contact arrays:

■ Creating Contact Arrays, 308

■ Modifying Contact Arrays, 310

Creating Contact Arrays

You use the Create Contact Array dialog box to create a contact array.

To create a contact array:

1 In the Create Contact Force dialog box or the Modify Contact Force dialog box, right-click the Contact Array text box, point to Contact Array, and then select Create.

The Create Contact Array dialog box appears as shown next.

Normal force magnitude from the IMPACT function

Friction options (optional)



2 Enter values in the dialog box as explained in Table 34, and then select OK.

Table 34. Contact Array Options

In the text box: Enter the following:

Contact Array Name Name used to identify the contact array.

Stiffness Force generated for each unit of penetration depth.

Force Exponent Exponent of the force deformation characteristic.

Damping Maximum viscous damping coefficient.

Penetration Depth Penetration depth at which full damping is applied.

Static Friction Coefficient (µs)

Proportion of normal force applied in the opposite direction of relative motion from zero velocity to static threshold velocity.

Static Friction Slip Velocity (Vs)

Velocity at which full value of the static friction coefficient is applied.

Dynamic Friction Coefficient (µk)

Proportion of normal force applied in the opposite direction of relative motion, from slip velocity to dynamic transition velocity.

Dynamic Friction Transition Velocity (Vk)

Velocity at which the value of the dynamic friction coefficient has fully transitioned from the static friction coefficient.



Figure 90. Friction Coefficient Parameters

Modifying Contact Arrays

You modify contact arrays using either the Create Contact Force or Modify Contact Force dialog boxes.

To access the Modify Contact Array dialog box:

1 In the Create Contact Force Dialog box or the Modify Contact Force dialog box, right-click the Contact Array text box, point to the name of the contact array, and then select Modify.

The Modify Contact Array dialog box appears. The options for modifying a contact array are the same as the options for creating a contact array.

2 Change the parameters in the dialog box as explained in Table 34 on page 309.

Coefficient

Velocity

value



Force-Based Contact Considerations

Force-based contacts combine the detection and force generation of geometry or planes that come into physical contact. There are situations when the force-based contact methods require special consideration of the application and resulting numerical consequences. Table 35 explains some of the more common situations and provides suggestions, methods, and information on how to work with them.

Table 35. Contact Force Situations and Considerations

Situation: Considerations:

ADAMS finds a solution where the surfaces have penetrated too far during a converged integrator step. This causes an undue reaction force from the penetrated surface on the next step.

Increase the number of time steps or specify the maximum integrator step. For information on simulation settings, see Changing Solution Settings for Dynamic Simulations on page 147 of the guide, Simulating Models in ADAMS/View.

Penetration distance is not accounted for in the friction calculation. There is no mathematical foundation for including this effect.

In most cases, you can ignore this because the effect is minimal. If the effect causes validation issues, adjust the stiffness in the relevant contact array to reduce the penetration achieved during the simulation.

Planar geometry that markers define in contacts have infinite span. Although geometry coincident with the marker may be finite, the contact force continues to act in the entire mathematical plane.

Be aware of the infinite plane when building models with contact forces



Circles and spheres are considered infinitely solid. The material is either completely within the shape or extends infinitely out of the shape. Planar geometry defined by markers in contact have infinite depth.

Circles and spheres are considered infinitely solid to prohibit the possibility of finding a solution on the other side of the geometric boundary. Use the proper inside/outside contact pair for the modeling situation.

Contact is a numerically discontinuous event. Even though the implementation includes methods to gradually transition the contact forces, these transitions require considerable integrator work to find a solution.

Consider the transitional parameters in the contact array, such as force exponent and penetration depth, to ensure that discontinuities are reasonably defined. Perform simulations with more output steps or specify a smaller integrator maximum step size.

Friction is a numerically discontinuous phenomenon and requires additional integrator work to solve, especially at low velocities.

Consider the friction parameters in the contact array, such as the transitional velocities, to ensure that discontinuities have reasonably defined.

Special conditions, such as “sticking,” “ jamming,” or “wedging,” that complex friction cause are difficult to reproduce.

The friction used in the contact forces is simplified to enhance its robustness. Use joint friction when complex friction phenomena is expected or required.

Table 35. Contact Force Situations and Considerations (continued)




The geometry and markers defining a two-dimensional curve contact must remain in the same xy plane during a simulation

When ADAMS/View creates a curve contact, it creates a reference marker for each piece of geometry in the contact. The reference markers indicate the direction and orientation of the geometry and the contact force. It places the markers and geometry in the same xy plane and at the same z orientation. The geometry and markers must remain in this plane during simulations.

If you import geometry from a CAD package to be used in a contact, its markers and geometry may not be aligned correctly.

Therefore, make sure that the geometry that define a two-dimensional contact are in the same xy plane as the reference markers and remain in that plane during simulations. Use kinematic constraints, such as planar joints, to keep them in alignment.

Two-dimensional curves used in contact must be well defined for the mathematical methods to work.

Define curves in two dimensions only and ensure that the curves are smooth and continuous, with no loops, coincident points, or overlaps.

For two-dimensional contact forces, open curves are ill-defined at endpoints.

Use closed curves when possible and build open curves so that contact does not occur near the ends.

Table 35. Contact Force Situations and Considerations (continued)




9 Storing and Accessing Data

OverviewUsing data elements, you can create and manage the storage of alpha-numeric information used in your model. Data elements include arrays, curves, splines, matrices, and strings. After creating data elements, you can reference them in the definition of modeling objects.

Note that data elements by themselves do nothing. They simply hold supporting data for other ADAMS elements or for your user function expressions or subroutines. For example, you reference matrices in the definition of a linear state equation. In addition, a linear state equation uses arrays of variables to define input, output, and state characteristics. You can also use curves to create contact constraints.

The next sections explain each type of data element and how to create them.

■ Types of Data Elements and Their Uses, 316

■ Creating Data Element Arrays, 317

■ Creating Data Element Curves, 322

■ Creating Data Element Splines, 332

■ Creating Data Element Matrices, 352

■ Creating Data Element Strings, 364


Storing and Accessing Data316

Types of Data Elements and Their UsesThe data elements are listed in the table below:

Table 36. Data Elements

The element: Does the following: Can be used with:

Array Defines a list of input values, variables, or initial conditions.

Linear state equations, general state equations, transfer functions, and ARYVAL run-time function.

Curve Defines a three-dimensional parametric curve whose points you can specify directly or through a subroutine.

Curve-to-curve and point-to-curve constraints, B-spline curve geometry, and CURVE run-time function.

Spline Defines discrete data for interpolation.

AKISPL and CUBSPLrun-time functions.

Matrix Inputs a two-dimensional array of numerical values.

Linear state equations, curves, and multi-point forces.

String Defines a character string. Tires, TIRSUB user-written subroutine, and GTSRTG user-written subroutine utility.



Creating Data Element ArraysAn array defines a list of input variables, state variables, output variables, and initial conditions associated with system elements, such as general state equations, linear state equations, and transfer functions. You can also use general arrays to define lists of constants. You can access the values in function expressions or user-written subroutines. (For information on system elements, see Using System Elements to Add Equations on page 365.)

The next sections explain more about arrays:

■ Types of Arrays, 318

■ Determining Array Size, 319

■ Creating and Modifying an Array, 320



Types of Arrays

There are four types of arrays:

■ General/Initial Conditions - Define an array of constants used as initial conditions for a system element or user-written subroutine.

■ States (X) and Outputs (Y) - Designate the state or output variable arrays for a system element, such as a linear state equation, general state equation, or transfer function. ADAMS/Solver, the analysis engine, computes these values during a simulation.

To use the arrays, you reference them in function expressions. You can reference the array as the state or output variable array of only one system element in a model (for example, only one linear state equation or one general state equation).

For more information on system elements, see Using System Elements to Add Equations on page 365.

■ Inputs (U) - An array that groups together a set of variables used to define the inputs for a system element. ADAMS/View computes variable values from the specified variable data elements.

The inputs (U) and the initial conditions arrays can exist independently, and do not need to be referenced by another system element.

Both function expressions and user-written subroutines can access the array values. Function expressions use the function ARYVAL (ARRAY_NAME, COMPONENT) to access the values. ARRAY_NAME specifies the name of the array, and COMPONENT specifies the position of the desired value in the array definition.

You should note that you can only access states (X), outputs (Y), and inputs (U) arrays in functions because the initial condition array is not accessible in the model definition. You can access the initial condition array in a user-written subroutine. To access all the elements of an array, call the subroutine SYSARY. To access one element of an array in a subroutine, call the subroutine SYSFNC. For more information on subroutines, see the guide, Using ADAMS/Solver Subroutines.



Determining Array Size

For the states (X) and outputs (Y) arrays, the system element in which the arrays are referenced automatically determines the size of the array and checks it against the array size, if you specify one. For initial conditions and general arrays, ADAMS/View determines the actual size of the array during parsing, as it counts the number of values. When you provide an array size, ADAMS/View checks the count for consistency if you request size checking.

If you specify the size of an array, it should match the number of values or variables in the array or the size needed for the associated element. Table 37 lists the sizes for arrays used in different system element equations.

Table 37. Array Sizes

For arrays used in: The array size is:

Linear state equation (LSE)

■ States (X) array size must be the same size as the row dimension of the matrix used to define the state transition matrix for the linear system.

■ Outputs (Y) size must be the same size as the row dimension of the matrix used to define the output matrix for the linear system or the matrix used to define the feed forward matrix for the linear system.

Transfer functions (TFSISO)

■ States (X) size is determined by the transformation from polynomial ratio type to canonical state-space form, which is a set of coupled, linear, constant-coefficient differential equations and a single algebraic equation.

■ Outputs (Y) size is always 1.

General state equations (GSE)

■ States (X) size is the same as the number defined in the matching general state equation definition.

■ Outputs (Y) size is the same as the number of output equations, as defined in the same general state equation definition.



Creating and Modifying an Array

To create or modify an array data element:

1 From the Build menu, point to Data Elements, point to Array, and then select either New or Modify.

2 If you selected:

■ New, the Create /Solver Array dialog box appears, as shown below, and you should continue with Step 3.

■ Modify, the Database Navigator appears. Select a data element array to modify. For more information on the Database Navigator, see Navigating Through a Modeling Database on page 147 in the guide, Learning ADAMS/View Basics.

The Modify /Solver Array dialog box appears. It contains the same options as the Create /Solver Array dialog box shown below.

3 Accept the default name or assign a new name.

Tip: You might find it easier to track which array element goes with which system element if you name the array elements and the corresponding system elements with like names. For example, the states (X) array that goes with general state equation GSE_100 would be ARRAY_100; the inputs (U) array would be ARRAY_101; and the outputs (Y) array would be ARRAY_102.

Options changedepending on the type of array



4 Select the type of array that you want to define. Refer to Types of Arrays on page 318 for an explanation of the different array types. The dialog box changes depending on the selection you make.

5 Depending on the type of array you are creating or modifying, enter or change the values in the dialog box as explained in the next table, and then select OK.

Table 38. Dialog Box Options

To create/modify:

Do the following:

General and initial conditions array

1 In the Values text box, enter the values to be stored in the array.

2 If you want ADAMS/View to check the size of the array, select Check Array Size.

States (X) 1 In the Correct Size text box, enter the size of the array.


Outputs (Y) 1 In the Correct Size text box, enter the size of the array.


Inputs (U) 1 In the Variables text box, enter the variables to be stored. If the array is used as input to a transfer function, then you can only enter one variable.

2 In the Correct Size text box, enter the size of the array, and, if you want ADAMS/View to check the size of the array, select Check Array Size.



Creating Data Element CurvesA curve data element defines a three-dimensional parametric curve that you can reference when:

■ Creating a pin-in-slot or curve-on-curve cam

■ Creating a geometric element called a B-spline

■ Writing function expressions

You can define a curve using data points (curve points or control points) or a user-written subroutine:

■ Curve points - When you define a curve using curve points, ADAMS/View creates a uniform B-spline that fits the points that you specify. You define the data points in a matrix element.

■ Control points - When you define a curve using control points, ADAMS/View creates a uniform B-spline defined by the control points. The curve is attracted to the points, but does not hit the points. You define the curve points in a matrix element.

■ Subroutine - To use a different type of curve or to model an analytically defined curve, such as a helix, you can write a CURSUB user-written subroutine to compute the curve coordinates and derivatives.

The x, y, and z coordinates of a point on a parametric curve are functions of an independent parameter, alpha. As alpha varies from its minimum value to its maximum value, the functions x(alpha), y(alpha), and z(alpha) sweep out points on the curve. A simple example of a parametric curve is the helix defined by the following equations:

x = cos(alpha)y = sin(alpha)z = alpha



The next sections explain how to define and create a curve element:

■ Steps in Defining a Curve, 323

■ About Defining a Curve With Data Points, 325

■ About Defining a Curve With a Subroutine, 327

■ About Specifying Open or Closed Curves, 327

■ Using Curve Elements in Your Model, 328

■ Creating or Modifying a Curve Element, 329

Steps in Defining a Curve

To create a curve using curve or data points that are defined in a matrix element or using a user-written subroutine, you perform the steps listed in the figure below:

Figure 91. Curve Creation Steps

Create a Create a curveelement matrix element

Step 1: Step 2:

Create b-splinegeometry

Step 3:

or subroutine

Use thecurve in your

Step 4:

model

Optional



Each step is explained below.

■ Step 1: Create a matrix element or subroutine - The first step in creating a curve is to create a matrix element that defines the points that make up the curve or create a subroutine that computes the curve coordinates and derivatives.

■ Step 2: Create a curve element - Next, you create a curve element that defines how ADAMS/View should create the curve, such as define whether or not is open or closed and reference either a matrix element or subroutine.

■ Step 3: Create B-spline geometry - You can optionally create the necessary geometry for your curve so that you can view it on the screen. You create the B-spline geometry using the Command Navigator. The command sequence is:

Geometry → Create → B-spline

Note: If you create spline geometry through the ADAMS/View part library as explained in Creating Splines on page 28, ADAMS/View automatically creates the curve and matrix elements for you. You can substitute your curve values for the values ADAMS/View creates. For information on modifying a spline, see Modifying Rigid Body Geometry on page 80.

■ Step 4: Use the curve in your model - Once you’ve created a curve element, you can use it in your model.



About Defining a Curve With Data Points

When you create a curve, you define whether the data points stored in the matrix element are control or curve points. In addition, you specify whether or not the curve is open or closed and the way in which ADAMS/View fits the curve to the curve points. The next sections explain more about these options.

Specifying Control Points

When you define the points stored in a matrix element as control points, you define points through which ADAMS/View should form a uniform B-spline. The curve starts at the first control point and ends at the last. In between, it is attracted to, but does not necessarily hit, the intermediate control points.

ADAMS/View uses a uniform knot vector with quadruple multiplicity at both ends, ensuring that the curve passes through starting and ending points. ADAMS/View parameterizes a B-spline starting at -1 and ending at +1. The following figure shows a curve that was created from control points.

Figure 92. Curve from Control Points

Controls points



Specifying Curve Points

A more direct way to define the curve is to supply curve points. ADAMS/View computes a tensioned B-spline that fits the curve points. Again, ADAMS/View parameterizes the curve from -1 to +1. Closed curves always exactly fit the curve points. The tension factor indicates the degree of curviness desired in the interpolation. If the tension factor is 0, the result is a cubic spline. If the tension factor is large, the result is nearly a polygonal line. Figure 93 shows a set of curve points and several fitted curves with different values of tension.

Figure 93. Curve from Curve Points with Differing Tension Values

Tension = 0Tension = 5Tension = 100



About Defining a Curve With a Subroutine

You can define a user-written subroutine CURSUB that computes the curve coordinates and derivatives. For more information, see the guide, Using ADAMS/Solver Subroutines.

About Specifying Open or Closed Curves

A curve can be open or closed. A closed curve meets at the ends, connecting the curve at minimum and maximum parameter values. An open curve does not meet at the ends.

If you create an open curve, ADAMS/View does not allow a pin-in-slot or curve-on-curve contact point to move beyond the end of the curve. ADAMS/View, however, automatically moves a pin-in-slot or curve-on-curve contact point across the closure of a closed curve, if needed. For example, you can model a cam profile as a closed curve, and ADAMS/View allows the follower to move across the closure as the cam rotates.

ADAMS/View stops the simulation if a pin-in-slot or curve-on-curve contact point is prescribed to move off the end of the curve. You should ensure that the curve defined includes the expected range of contact.



Using Curve Elements in Your Model

Once you’ve created a curve element, you can use it to define a pin-in-slot or curve-on-curve cam, as geometry of a part, or in a function expression.

■ Cams - When you create or modify a cam, you can pick the geometric curves that you’ve created from the curve element or you can modify the cam to use a different curve. For more information on using the curve element in the definition of cams, see Working with Cams on page 272.

■ Geometry of a part - You can use the curve that you create in the definition of a part. For example, when you create a construction geometry spline using the geometric modeling tools as explained in Creating Splines on page 28, ADAMS/View automatically creates a curve element defining the spline. You could replace the default curve element with a curve element that you create. You could also create an empty part using the Table Editor, and modify it to contain a curve element.

■ Function expression - You can use the curve element as the input to a function, such as CURVE (B-Spline fitting method). For more information on using curves in a function expression, see Spline Functions on page 413 of the guide, Using the ADAMS/View Function Builder.



Creating or Modifying a Curve Element

To create or modify a curve data elemen

1 From the Build menu, point to Data Elements, point to Curve, and then select either New or Modify.

2 If you selected:

■ New, the Data Element Create Curve dialog box appears and you should continue with Step 3.

■ Modify, the Database Navigator appears. Select a data element curve to modify. For more information on the Database Navigator, see Navigating Through a Modeling Database on page 147 in the guide, Learning ADAMS/View Basics.

The Data Element Modify Curve dialog box appears. It contains the same options as the Data Element Create Curve dialog box.


4 Assign a unique ID number to the curve element, if desired. Enter a positive integer or enter 0 to have ADAMS/View set the ID for you.

The ID is an integer used to identify the element in the ADAMS/Solver dataset (.adm) file. You only need to specify an ID number if you are exporting the model to an ADAMS/Solver dataset, and you want to control the numbering scheme used in the file, or if you are using the subroutine CURSUB.

5 Add or change any comments about the curve element that you want to enter to help you manage and identify the element. You can enter any alphanumeric characters. The comments that you create appear in the information window when you select to display information about the object, in the ADAMS/View log file, and in a command or dataset file when you export your model to these types of files.

6 Set Closed to either no to create an open curve or yes to create a closed curve.

7 Set the option menu in the middle of the dialog box for how you want to define the curve (either from a matrix or a subroutine). The dialog box changes depending on the selection you made.



8 Depending on the type of curve you are creating, enter values in the dialog box as explained in the next two tables and select OK.

Table 39. Matrix Options


Matrix to be used In the Matrix Name text box, enter the matrix name. To browse for a matrix in the Database Navigator or select a matrix from a list, right-click the box, and then select the appropriate command.

How the curve is to be fit through the points contained in the matrix data element

From the Fit Type option menu, select either:❖ Control Points - The matrix contains control

points that define a uniform B-spline based on cubic polynomials. For more information, see Specifying Control Points on page 325.

❖ Curve Points - The matrix contains a row for each point and three columns containing the x, y, and z coordinates of the points. For more information, see Specifying Curve Points on page 326.

You must supply at least four control or curve points.

Tension In the Tension text box, enter the tension factor used with the tensioned B-spline fitting algorithm for curves defined with curve points. For more information, see About Specifying Open or Closed Curves on page 327.



Table 40. Subroutine Options


User-written subroutine to be used

In the User Function text box, enter the subroutine name. To browse for a subroutine in the Database Navigator or select a subroutine from a list, right-click the box, and then select the appropriate command.

Minimum and maximum curve parameters

Enter the following:❖ Minimum Parameter - Enter the minimum value of

the curve parameter for a user-written curve.

❖ Maximum Parameter - Enter the maximum value of the curve parameter for a user-written curve.



Creating Data Element SplinesA spline creates a continuous function from a set of data points. Splines are useful when you have test data or manufacturer specifications that specify the value of a function at several points. The spline can define a curve (two-dimensional, x, y) or a surface (three-dimensional, x, y, z).

You can use splines to create nonlinear functions for motions, forces, or other elements that use functions. In the case of a motion, the points define the displacement, velocity, or acceleration as a function of time, displacement, velocity, or another ADAMS quantity.

The ADAMS/View spline element contains the x, y or x, y, z data points that you want to interpolate. To use the spline element, you must write a function expression that includes ADAMS spline functions (such as AKISPL or CUBSPL) or create a user-written subroutine that calls one of the spline utility subroutines (AKISPL or CUBSPL subroutine). The functions or subroutines interpolate the discrete data.

The next sections explain more about using and creating splines in ADAMS/View:

■ Example of Using Splines, 333

■ Ways to Create Splines in ADAMS/View, 335

■ Curve-Fitting Techniques in ADAMS/View, 335

■ Using the Spline Editor, 336

■ Using the General Method, 347

■ Modifying Splines, 350

■ Tips and Cautions When Creating Splines, 351



Example of Using Splines

In this example, we use a spline to relate the force of a spring to its deformation. The values in Table 41 show the relation of a force in a spring to its deformation.

Using this table, you can determine the force when deflection equals -0.33, and the force when deflection equals -0.17. You cannot, however, determine the force when the deflection is -0.25. To determine the force at any deflection value, ADAMS/View creates a continuous function that relates deflection and force. The continuous approximation is then used to evaluate the value of the spring force at a deflection of -0.25. If you input two sets of values (x and y) using a spline data element, you can define the curve that the data represents.

You would then use the spline data element in a function or subroutine that uses cubic spline functions to fit a curve to the values. The curve allows ADAMS/View to interpolate a value of y for any value of x.

Table 41. Data Relating Spring Force to Spring Deflection Force

When the deflection is: The force is:

-0.33 -38.5

-0.17 -27.1

-0.09 -15.0

0.0 0.0

0.10 10.0

0.25 30.0

0.40 43.5

0.70 67.4



Briefly, the steps that you’d perform to use the spline data element to define the force deflections are:

1 Create the spline as explained in Using the Spline Editor on page 336 or Using the General Method on page 347.

2 Build a simple nonlinear spring-damper, and then modify it to use the spline. To use the spline in the spring-damper definition, under Stiffness and Damping in the Spring-Damper Modify dialog box, change the stiffness coefficient to Spline: F=f(defo). ADAMS/View builds a function expression for you, using AKISPL and modeled spring length as free length.

For more information on creating and modifying spring-dampers, see Working with Translational Spring-Dampers on page 233.

Note: You can also use a single- or multi-component force to define the force deflections. In this case, you would select Custom as you create the force, and then modify the force by entering a function expression, such as:

You can use the Function Builder for assistance in building the expression.

-akispl(dm(.model_1.PART_1.MAR_4,.model_1.ground.MAR_2) - 200.0, 0.0, .model_1.SPLINE_1)



Ways to Create Splines in ADAMS/View

You can enter spline data into ADAMS/View in several ways:

■ Use the Spline Editor to create a spline in ADAMS/View. The Spline Editor provides you with a table for inputting values and a plotting window for viewing the results and the effects of different curve-fitting techniques. For more information, see Using the Spline Editor on page 336.

■ Use the general method to define spline data points by referencing either a file containing a set of points or results from a simulation. You can also enter numerical values directly.

■ Import tabular data into ADAMS/View and save it as a spline. For information on how to import test data as splines, see Importing Test Data on page 40 of the guide, Exchanging Data in ADAMS.

■ Use the data from a plot and save it as a spline. For more information, see Creating Splines from Curves on page 96 of the guide, Using ADAMS/PostProcessor.

Curve-Fitting Techniques in ADAMS/View

ADAMS/View uses curve-fitting techniques to interpolate between data points to create a continuous function. If the spline data has one independent variable, ADAMS/View uses a cubic polynomial to interpolate between points. If the spline data has two independent variables, ADAMS/View first uses a cubic interpolation method to interpolate between points of the first independent variable and then uses a linear method to interpolate between curves of the second independent variable.

For information on the different spline functions that use these curve fitting techniques, see the definitions of the functions in the guide, Using the ADAMS/View Function Builder, and for a comparison of the different methods, refer to Spline Functions on page 413 in the same guide.



Using the Spline Editor

The Spline Editor provides a tabular or plot view of your spline data for editing and plotting. You can drag points on your spline plots and see the effect of different curve-fitting techniques on your spline. You can also select linear extrapolation and view its effect.

Using the Spline Editor, you can create a two- or three-dimensional splines. Note, however, that the Spline Editor does not display a three-dimensional spline in plot view.

The next sections explain how to work with the Spline Editor:

■ Displaying the Spline Editor, 337

■ Setting the View of the Spline Editor, 338

■ Specifying Two- or Three-Dimensional Splines, 339

■ Specifying Linear Extrapolation, 340

■ Plotting a Spline, 340

■ Editing a Spline in Tabular Format, 344



Displaying the Spline Editor

To display the Spline Editor:

1 From the Build menu, point to Data Elements, point to Spline, and then select New.

The Spline Editor appears.

Figure 94. Spline Editor in Tabular Format



Setting the View of the Spline Editor

You can choose to view your spline as a plot or as a table in tabular format:

■ Plot view - Viewing the spline as a plot lets you view the data in the spline as a curve and apply several operations on the curve, such as change the curve-fitting techniques being used to create the curve, view the results of linear extrapolation, or view the changes you made against the original spline values.

■ Tabular view - Viewing a spline in tabular view gives you the most accuracy for setting the location of the spline data points. It also lets you quickly add points by inserting rows of data.

To set the view of the Spline Editor:

■ Set View As to either Tabular Data or Plot.



Specifying Two- or Three-Dimensional Splines

You can select to create two- or three-dimensional splines. When you create a three-dimensional spline in tabular view, the Spline Editor displays a second column for adding z values. The following figure shows the additional column. Note that you cannot view the z dimension in plot view. You also need to recompute the spline in plot view to set a three-dimensional spline.

Figure 95. Spline Editor with Z Column

To set the type of spline:

1 Set Type to either:

■ y=f(x) (2D) to create or edit a two-dimensional, curve spline.

■ y=f(x,z) (3D) to create or edit a three-dimensional, surface spline.

2 Select Recompute if you are in plot view to see the effect of the changes. For more information on recomputing plots, see Changing Plotting Methods and Recomputing the Plot on page 343.

Z column



Specifying Linear Extrapolation

Linear extrapolation extends the curve created from the spline values by estimating the values that follow from the spline values.

To specify linear extrapolation:

■ Select Linear extrapolation.

To view the results of the linear extrapolation on the spline:

■ Change the Spline Editor to plot view and select Extrapolation Tails.

Plotting a Spline

You can plot a spline to view curves that would be generated from the curves. In plot view, you also have the options of:

■ Setting the View of the Spline Plot, 341

■ Editing Spline Data Points, 342

■ Changing Plotting Methods and Recomputing the Plot, 343

Note: You can change the spline plot properties, such as the color of a curve.



Setting the View of the Spline Plot

There are several ways you can change the view of the spline plot, including viewing the slope of the curve, turning off the display of the data points that make up the spline, and more. Be default, ADAMS/View displays a curve and hotpoints representing the spline data points.

To view the curve that ADAMS/View generates from the data points:

■ Select Spline Curve.

To view the slope (derivative) of a curve:

■ Select Slope Curves.

To view the spline data points:

■ Select Symbols.

Note: You can edit the data points. See Editing Spline Data Points on page 342.

To retain the original curve as you edit the data points:

■ Select Memory Curves.

To view the effect of linear extrapolation:

■ Select Extrapolation Tails.

For more on setting up linear extrapolation, see Specifying Linear Extrapolation on page 340.



Editing Spline Data Points

Hotpoints appear on the curve in the plot window at each data point in the spline. You can drag the hotpoints to change the data point locations. The hotpoints are shown in the figure below.

Figure 96. Hotpoints on a Spline

To edit data points:

1 Click the data point that you want to edit. Note that you must turn on the viewing of symbols.

Hotpoints appear at each data point.

2 Position the cursor on a hotpoint and drag the hotpoint to the desired location.

Hotpoints



Changing Plotting Methods and Recomputing the Plot

By default, ADAMS/View displays a curve from your spline data points using 50 curve points and the Akima curve-fitting method. You can change the number of points and the method used to calculate the curve. You must recompute the spline to see the effect of these changes. As you recompute the spline, you can select to use the values stored for the spline in the modeling database or use the values as you’ve edited them.

To change the number of points used to display a curve:

■ In the Points text box, enter the number of points.

Note: Changing the number of points only changes the display of the curve, making it smoother or more coarse. It does not change the number of data points in the curve.

To set the curve-fitting technique:

■ Set Spline Type to either AKISPL or CUBSPL.

To recompute the curve:

1 Select Recompute.

ADAMS/View asks you if you want to use the current values for the spline or the ones stored in the modeling database.

2 Select one of the following:

■ Yes to use the values in the database.

■ No to use the edited values.



Editing a Spline in Tabular Format

Editing a spline in tabular format gives you the most control over the location values. The following sections explain how to use the Spline Editor in tabular format:

■ Working with Cells, 344

■ Viewing Entire Contents of a Cell, 345

■ Resizing Columns, 346

■ Adding and Removing Rows, 346

Working with Cells

You can change any of the values in the cells of the Spline Editor tables.

To enter text in a cell:

1 Click the cell. The text cursor appears in the cell.

2 Type the text you want and press Enter.

To move to the next cell:

■ Press Tab.

To move to the previous cell:

■ Press Shift + Tab.

To move up to the previous row or down to the next row:

■ Select the up or down arrow keys.

To cut or copy text in cells:

1 Select the text in the cell that you want to cut or copy.

2 Right-click the cell containing the text to be cut or copied, and then select Copy or Cut.

To paste text:

■ Right-click the cell where you want to insert the text, and then select Paste.



Viewing Entire Contents of a Cell

Often, information displayed in a cell of the Spline Editor is longer than the width of the cell. When this happens, ADAMS/View displays the first portion of the information. In UNIX, it also displays an arrow next to the cell to indicate that there is more information than can fit in the cell. Figure 97 shows the Spline Editor as it appears in UNIX when cells contain more information than can be displayed at once.

Figure 97. Cells with Partial Information (UNIX Only)

To view the rest of the cell:

■ Click in the cell. ADAMS/View displays the last portion of the information in the cell.

Arrow indicatingmore information



Resizing Columns

You can change the size of any column displayed in the Spline Editor.

To resize a column:

1 Point to the right border of the column heading that you want to resize. The cursor changes to a double-sided arrow.

2 Drag the cursor until the column is the desired size.


Adding and Removing Rows

You can add rows to the X and Y table and to the Z table if you are creating a three-dimensional spline.

To add a row to the beginning of the X and Y table:

■ Select Append row to X & Y data.

To add a row to the end of the X and Y table:

■ Select Prepend row to X & Y data.

To add a row after a particular X and Y row:

■ Enter a row number in the Insert Row After text box and select Insert Row After.

To add a row to the end of the Z table:

■ Select Append Z Value.

To remove a row from either the X and Y or Z table:

■ Enter the row number in the Remove Row text box and select Remove Row.



Using the General Method

The general method of creating splines lets you define the data points of the spline using:

■ File - The file is in RPC III, DAC, or user-defined format. The file contains x, y, and, optionally, z values that define the spline data points. You can specify that ADAMS/View only use a particular named block or channel within the file. You can only enter time response data in RPC III and DAC files if you are using ADAMS/Durability. For more information on using splines in ADAMS/Durability, see the guide, Using ADAMS/Durability.

Entering a user-defined file causes ADAMS/Solver to call the user-written subroutine SPLINE_READ, which you must provide. For more on how to define a SPLINE using a user-defined file, see the example in SPLINE_READ on page 147 of the guide, Using ADAMS/Solver Subroutines.

■ Result of a simulation - You can also use the results of a simulation as input to a spline by referencing result set components. For more on result set components, see About Simulation Output on page 6 of the guide, Simulating Models in ADAMS/View.

■ Numerical values directly input in the dialog box - You can directly input x, y, and, optionally, z values in the dialog box.

To create a general spline:

1 From the Build menu, point to Data Elements, point to Spline, and then select General.


3 Assign a unique ID number to the spline, if appropriate. Enter a positive integer or enter 0 to have ADAMS/View set the ID for you.

The ID is an integer used to identify the element in the ADAMS/Solver dataset (.adm) file. You only need to specify an ID number if you are exporting the model to an ADAMS/Solver dataset, and you want to control the numbering scheme used in the file.



4 Add any comments about the spline that you want to enter to help you manage and identify it. You can enter any alphanumeric characters. The comments that you create appear in the information window when you select to display information about the object, in the ADAMS/View log file, and in a command or dataset file when you export your model to these types of files.

5 Set Linear Extrapolate to yes to extrapolate a spline by applying a linear function over the first or last two data points. By default, for user-defined files, ADAMS/Solver extrapolates a spline that exceeds a defined range by applying a parabolic function over the first or last three data points. For RPC III or DAC files, the default method of extrapolation is zero-order (constant).

6 Depending on how you are creating the spline, enter or change the values in the dialog box as explained in the next table and select OK.

Table 42. Dialog Box Options

To create a spline from:

Do the following:

File 1 Set the option menu to File.2 Enter the name of the file.3 If desired, enter the block within the file from

which you want ADAMS/View to take the data. The block must be specifically named in the file.

4 Set the channel from which to take the data. This option is for use with time response data in RPC III files only. For more information see the guide, Using ADAMS/Durability.

Result set components

1 Set the option menu to Result Set Component.2 Select the result set components to be used for the x

and y values.



Numerical input 1 Set the option menu to Numerical.2 Enter the x, y, and, optionally, z values in the text

boxes. Note the following:

■ Specify at least four x and y values. The maximum number of x values, n, depends on whether you specify a single curve or a family of curves.

■ Values must be constants; ADAMS/Solver does not allow expressions.

■ Values must be in increasing order:x1< x2 < x3, and so on.

Table 42. Dialog Box Options (continued)

To create a spline from:

Do the following:



Modifying Splines

The method you use to modify a spline (Spline Editor or general method) depends on the input to the spline.

■ Numerical values or result set components - If the input for the spline data points was numerical values or result set components, then when you select to modify the spline, ADAMS/View displays the Spline Editor because it provides the most convenient method for directly editing values.

■ File - If the method of input for the spline data points was a file, ADAMS/View displays the Data Element Modify Spline dialog box, for you to change the file or interpolation method using the general method.

Note that because you do not always modify splines using the same method that you used to create them, you cannot change the input to the spline data points without first deleting the spline and making it again. For example, if you created a spline using the result set component TIME as the x values, and you want to change the spline to reference the result set component that defines the force on a part, you would have to delete the spline and create it again referencing the new component. In addition, if you defined spline data points using direct numerical values and you want to instead reference a file, you must delete the spline and make it again using the general method.

To modify a spline:

1 From the Build menu, point to Data Elements, point to Spline, and then select Modify.

The Database Navigator appears.

2 Select a data element spline to modify. For more information on the Database Navigator, see Navigating Through a Modeling Database on page 147 in the guide, Learning ADAMS/View Basics.

The Spline Editor or Data Element Modify dialog box appears.

3 Follow the instructions in Using the Spline Editor on page 336 or Using the General Method on page 347, as appropriate.



Tips and Cautions When Creating Splines

When selecting points to represent a curve or surface:

■ Crowd points in regions with high rates of change.

■ Spread out points in regions with slow rates of change.

The x and z data must cover the anticipated range of values. However, the following situations sometimes cause ADAMS/Solver to evaluate a spline outside of its defined range:

■ ADAMS/Solver occasionally approximates partial derivatives using a finite differencing algorithm.

■ ADAMS/Solver occasionally attempts an iteration that moves the independent variable outside of its defined range. If this occurs, ADAMS/Solver issues a warning message and extrapolates the four closest spline points. If the extrapolation is poor, ADAMS/Solver can have difficulty reaching convergence, which may affect the results.

To avoid these problems, try to use real points, and extend spline values 10 percent beyond the total dynamic range.



Creating Data Element MatricesA data element matrix lets you input a two-dimensional array of numerical values. You use the matrix primarily to support other elements such as curves, linear state equations, multi-component forces, and more. You can assign the entries in a matrix directly or specify the name of a data file from which ADAMS/View should read the values. You can also use the results of a simulation as input to a matrix by referencing result set components.

The next sections explain more about matrices:

■ Matrix Format Types, 352

■ Creating or Modifying a Matrix, 353

■ About the Format for Matrix Data Files, 360

Matrix Format Types

A matrix data element is a general M N array that can be a rectangular or square two-dimensional matrix or a row or column matrix. You can enter the data in a full or sparse format if you do not specify an external file:

■ Full format - You list all the M N values.

■ Sparse format - You list the row position, column position, and value for only nonzero entry values.

If one-third or more of the entries in a matrix are nonzero, we recommend that you use full format since it takes less time to create. If the matrix is mostly empty and entering each nonzero entry’s row position, column position, and value takes less time than entering all of the values, you should use the sparse format.

×

×



Creating or Modifying a Matrix

As previously explained, you can create a matrix by entering the values in full or sparse format, by getting them from a result set component, or by specifying a data file that contains the matrix values. The next sections explain how to create or modify a matrix using any of these methods.

■ Defining Matrices Using Full Format, 354

■ Defining Matrices Using Sparse Format, 356

■ Defining Matrixes Using Result Set Components, 358

■ Defining Matrices Using Data Files, 359

Note: You must create additional matrix elements in your ADAMS/View model if multiple matrices are to be read from the same file.



Defining Matrices Using Full Format

When you create or modify a matrix using full format, you enter all the values in the matrix. For more information on formats for matrices, see Matrix Format Types on page 352.

To create or modify a matrix using full format:

1 From the Build menu, point to Data Elements, point to Matrix, and then select either New or Modify.

2 If you selected:

■ New, the Create Matrix dialog box appears, as shown in Figure 98, and you should continue with Step 3.

■ Modify, the Database Navigator appears. Select a data element matrix to modify. For more information on the Database Navigator, see Navigating Through a Modeling Database on page 147 in the guide, Learning ADAMS/View Basics.

The Modify Matrix dialog box appears. It contains the same options as the Create Matrix dialog box shown below.

Figure 98. Create Matrix Dialog Box

Options changedepending on how you inputthe values for the matrix



3 In the Matrix Name text box, accept the default name or enter a new name.

4 Select the units that you want assigned for values in your matrix. Select no_units if you do not want units associated with the values. If you set the units for your matrix values, ADAMS/View automatically performs any necessary unit conversions if you ever change your default modeling units.

5 Select Full Matrix to enter all the values for the M N array.

6 Select either of the following:

■ To list the values in column order, select Enter Input Ordered by Columns.

■ To list the values in row order, select Enter Input Ordered by Rows.

7 From the next option menu, select User Entered Numbers to enter the values yourself.

8 In the Row Count and Column Count text boxes, enter the number of rows and columns in the matrix.

9 In the Values text box, enter the values in the matrix in either row or column order depending on the order you selected in Step 6 above. You can separate the values using a comma or by pressing Enter after each value.

Example: If you want to enter the following matrix of values in full format

:

enter the following in the text boxes:

■ Row Count - 4

■ Column Count - 2

■ Values - 1.364, 0.000, 0.000, 0.000, -3.546, 4.008, 0.000, 0.7999

10 Select OK.

×

1.364 0.000

0.000 0.000

3.546– 4.008

0.000 0.7999



Defining Matrices Using Sparse Format

When you create or modify a matrix using sparse format, you enter only nonzero values. For more information on formats for matrices, see Matrix Format Types on page 352.

To create or modify a matrix using sparse format:


2 If you selected:

■ New, the Create Matrix dialog box appears, as shown in Figure 98 on page 354, and you should continue with Step 3.


The Modify Matrix dialog box appears. It contains the same options as the Create Matrix dialog box shown in Figure 98 on page 354.



5 Select Sparse Matrix to enter the row position, column position, and value for only nonzero values.



6 Enter the following:

■ Row Index - Enter the row numbers, separated by commas, in your matrix containing nonzero values. Enter the row number each time there is a value in the row.

■ Column Index - Enter the column numbers, separated by commas, containing nonzero values. Enter the column number each time there is a value in the column.

■ Values - Enter the nonzero values in your matrix starting with the first column. Separate each value with a comma.

Example: If you want to enter the following matrix of values in sparse format

enter the following in the text boxes:

■ Row Index - 1, 3, 3, 4

■ Column Index - 1, 1, 2, 2

■ Values - 1.364, -3.546, 4.008, 0.7999

7 Select OK.

1.364 0.000

0.000 0.000

3.546– 4.008

0.000 0.7999



Defining Matrixes Using Result Set Components

You can only use a result set component as matrix values using full format and entering all the values stored in the result set component. For more on result set components, see About Simulation Output on page 6 of the guide, Simulating Models in ADAMS/View.

To define a matrix using result set components:


2 If you selected:






5 Select either of the following:

■ To list the values in column order, select Enter Input Ordered by Columns.

■ To list the values in row order, select Enter Input Ordered by Rows.

6 To obtain the values from the results of a simulation, select Result Set Component.

7 In the Result Set Component Names text box, enter the name or names of the components.

8 Select OK.



Defining Matrices Using Data Files

You can define any size matrix using an external data file. You can also specify in the data file whether you are entering the matrix values in full or sparse format. For more information on the format of matrix data files, see About the Format for Matrix Data Files on page 360.

To create or modify a matrix using a data file:


2 If you selected:






5 Select From a File.

6 Enter the name of the file containing the matrix values and the name of the matrix in the file. The name of the matrix is necessary even if the file contains only one matrix. You will need to create additional matrices to read other matrices from the same file. For more information, refer to About the Format for Matrix Data Files on page 360.

7 Select OK.



About the Format for Matrix Data Files

You can use a data file to read large matrices into ADAMS/View. There is no limit to the size of an array read from the file. The data file can be in one of three formats:

■ ADAMS/Solver format - An ADAMSMAT or ADAMSMAT2 format file consists of variable-length records that must be laid out as described in the following paragraphs. Table 43 lists the file format details.

■ Standard FSAVE or the optional MATSAVE format supported by the MATRIXx software package - See the MATRIXx literature for a description of the FSAVE and MATSAVE formats.

Although no other formats are supported, the ADAMSMAT option is fairly general because the format for reading in the data is specified within the file, and should meet your requirements.

The first record in any file type contains an 80-character header that indicates the format of the file as listed in the table below. The remainder of the first record can be used as a title to identify the kind of data in the file.

Table 43. Header Characters and File Formats

If the characters are:

Then the file format is:

ADAMSMAT or ADAMSMAT2

ADAMS/Solver code format

MATRIXx FSAVE format of the MATRIXx software package

MATSAVE MATSAVE format of the MATRIXx software package



Note that the specifications for the format of the data file are case-sensitive. Uppercase letters and a lowercase x must be used to indicate MATRIXx.

The second record contains only an integer n right-justified within the first five spaces (the I5 FORTRAN format). It tells how many matrices are contained in the file. The next several records (one or more) contain the alphanumeric names (eight characters or less) of all of the matrices in the file. The names are listed sequentially, four to a line, in eight-character fields separated by ten blanks. That is, the FORTRAN format for the records containing the matrix names is A8, 10X, A8, 10X, A8, 10X, A8.

Sets of contiguous records define each matrix. Without any intervening blank lines, the blocks of records begin immediately after the last line of matrix names. The first record in each block contains the name of the matrix in the first eight characters of the line. The code searches through the file until it finds the block of records corresponding to the name of the matrix element.

The first record of the block contains the type of matrix (either FULL or SPARSE) within the second eight spaces on the record. If the type is FULL, the next eight spaces (from 17 through 24) contain the string CORDER or RORDER to indicate that the values are listed by column or by row, respectively. Otherwise, if the type is SPARSE, the space is left blank. (For more information on full or sparse formats, see Matrix Format Types on page 352.)

The numerical values specified on the first record of the block include the:

■ Number of rows M in the matrix.

■ Number of columns N.

■ Total number of entries to be assigned values from the file.

If the matrix type is SPARSE, then the total number of entries must be less than or equal to (generally much less than) M N. If the matrix is FULL, the total number must be equal to M N.

■ For a matrix in the ADAMSMAT format, the values for M, N, and the total number of entries must be right justified in the fields 25 to 29, 30 to 34, and 35 to 39, respectively.

■ For a matrix in the ADAMSMAT2 format, the values for M, N, and the total number of entries must be separated by spaces.

××



The final entry on the first line of the block of records defining each matrix is the format specification for the records containing the values of the matrix. Beginning in column 40, 41 spaces are allowed for the character string containing the FORTRAN format specification, which must include delimiting parentheses. The lines of data begin on the next record and continue with successive records until the code has read into storage either M N values if the matrix is full or the total number specified if the matrix is sparse.

Table 44. Specifications for ADAMSMAT Data File

Item:Number of records: Contents:

Argument/Symbol:

FORTRAN format:

1 1 Header for the file ADAMSMAT A

2 1 Number of matrices in the file n I5

3 (n+3)/4 Names of the n matrices NAME 4 (8A,10X)

4 1 ■ Name of the matrix {FULL or SPARSE}{CORDER or RORDER if FULL or blank if SPARSE}

■ Number of rows, columns

■ Total number of entries

■ FORTRAN format specification

NAME

M,N,

number

FORMAT

A8,A8,A8,

315,

A41

5 variable ■ All entries in the matrix if FULL.

■ The indexes and nonzero entries in the matrix if SPARSE

A(I,J)

orI,J, A(I,J)

FORMAT

FORMAT

Note: Items 4 and 5 have to be repeated n times, once for each matrix named in Item 3.

×



For a full matrix, the code simply reads matrix entries sequentially from the file. If the matrix is sparse, organize the data in triplets; ADAMS/View reads the row and column indexes followed by the corresponding entry in the matrix. One triplet follows another until ADAMS/View has read the specified total number of values into the storage arrays.

If the file contains another matrix, the block of records defining its structure and containing its values must follow immediately after the last line of data for the previous matrix.

Table 45. Specifications for the ADAMSMAT2 Matrix File

Item: Number of records:

Contents: Argument or symbol:

FORTRAN format:

1 1 Header for the file ADAMSMAT2 A

2 1 Number of matrices in the file n I5

3 (n+3)/4 Names of the n matrices NAME 4 (8A,10X)

4 1 Name of the matrix{FULL or SPARSE}{CORDER or RORDER if FULL or blank if SPARSE}Number of rows, columns, and total number of entries

FORTRAN format specification

NAME

M,N,number

FORMAT

A8,A8,A8,

Values separated by spacesA41

5 variable All entries in the matrix if FULLorThe indices and nonzero entries in the matrix if SPARSE

A(I,J)orI,J, A(I,J)

FORMAT

FORMAT

Note: Items 4 and 5 have to be repeated n times, once for each matrix named in Item 3.



Creating Data Element StringsA string element defines a character string that you can refer to later in the execution of ADAMS/View or ADAMS/Solver. The character string cannot be broken and continued on the next line. It can, however, be longer than a single line. You can use the GTSRTG subroutine to retrieve the character string in a user-written subroutine. For example, you could use a string element to pass a file name to a user-written subroutine.

To create or modify a string:

1 From the Build menu, point to Data Elements, point to String, and then select either New or Modify.

If you selected New, the Data Element Create String Element dialog box appears. If you selected Modify, the Database Navigator appears.

2 If you selected:

■ New, the Data Element Create String Element dialog box appears, and you should continue with Step 3.

■ Modify, the Database Navigator appears. Select a data element string to modify. For more information on the Database Navigator, see Navigating Through a Modeling Database on page 147 in the guide, Learning ADAMS/View Basics.

The Data Element Modify String Element dialog box appears. It contains the same options as the Data Element Create String Element dialog box.

3 In the Name text box, enter the name that you want assigned to the string.

4 In the String text box, enter the string values.

5 Select OK.

10 Using System Elements to Add Equations

OverviewSystem elements let you create one or more general differential and/or algebraic equation that enables you to model system components that are not as easily represented by standard ADAMS/View modeling objects, such as parts, constraints, and forces.

System elements are useful for modeling components or subsystems that have dynamics of their own. You can use system elements to represent a control system, for example, or to model the dynamics of an electro-mechanical, hydraulic, or pneumatic actuator. You can also use system elements to compute simulation output. For example, you might calculate the energy dissipated in a damper.

This chapter introduces you to system elements. It contains the sections:

■ About System Elements, 366

■ Defining State Variables, 371

■ Using Differential Equations, 374

■ Defining Linear State Equations, 377

■ Defining General State Equations, 381

■ Defining Transfer Functions, 386


Using System Elements to Add Equations366

About System ElementsSystem elements allow you to add your own algebraic and differential equations, and corresponding states, to your model. ADAMS/Solver, the analysis engine, solves your equations simultaneously with the equations it generates from other modeling elements.

Your user-defined equations can depend on any states in the model, such as time, part motions, forces, or other user-defined states. In turn, you can reference your states in forces, system elements, and other modeling elements.

The next sections give you an overview of using system elements:

■ Types of System Elements, 367

■ Example of Using System Elements, 368

■ Controlling Equilibrium Values when Using System Elements, 369

■ Using Arrays with System Elements, 369

■ Terminology Used in System Elements, 370



Types of System Elements

The system elements are listed in the table below.

Table 46. System Elements

The system element: Defines:

Differential Equation

Differential equation that describes a user-defined variable in terms of its time derivative.

General state equation

System of explicit differential and (optionally) algebraic equations in state-space form. You use array data elements to specify inputs, outputs, and statements.

Linear state equation

System of constant coefficient, explicit, differential, and algebraic equations in the classic state-space format when used with associated array and matrix data elements.

Transfer function

Single-input, single-output transfer function as a ratio of two polynomials in the Laplace domain when used with associated array data elements.

State variable Scalar algebraic equation for independent use or as part of the plant input, plant output, or array data elements.



Example of Using System Elements

We’ve provided a complete example of using system elements in a model in the examples directory of your ADAMS installation directory. The example contains the following elements:

■ State variables

■ Arrays

■ Matrices

■ Implicit and explicit differential equations

■ Linear state equations

■ Transfer functions

The files you use to run the example are:

■ system_tutorial.cmd - Contains an ADAMS/View command file that builds a model containing the elements listed about.

■ system_tutorial.txt - Describes the model and its construction.

The path to the files is /install_dir/aview/examples/user_guide, where install_dir is where the ADAMS software is installed.



Controlling Equilibrium Values when Using System Elements

During a static simulation, ADAMS/Solver finds equilibrium values for user-defined differential variables (differential equations, general state equations, linear state equations, and transfer functions), as well as for the displacement and force variables. The equilibrium values it finds change the initial conditions for subsequent simulations. To help you control the static simulation results, ADAMS/View provides an option that you can set to keep the values constant. This option is called static hold. Static hold retains the user-specified initial conditions as the static equilibrium values.

If you do not set static hold, ADAMS/Solver sets the time derivatives of the user-defined variables to zero during a static simulation, and uses the user-supplied initial-condition values only as initial guesses for the static solution. Generally, the final equilibrium values are not the same as the initial condition values. ADAMS/Solver then uses the equilibrium values of the user-defined variables as the initial values for any subsequent simulation, just as with the equilibrium displacement and force values.

If you do set static hold, ADAMS/Solver retains the user-specified initial conditions as the static equilibrium values. Therefore, the final equilibrium values are the same as the user-specified initial conditions. Note that this does not guarantee that the time derivatives of the user-defined variable are zero after a static simulation.

Using Arrays with System Elements

You use array elements to represent the system states and outputs for linear state equations, general state equations, and transfer functions. You use the run-time function ARYVAL to reference states and outputs for these elements, instead of using ADAMS functions or callable subroutines that are dedicated expressly to the equations. For more information on arrays, see Storing and Accessing Data on page 315. For more information on the ARYVAL function, see the guide, Using the ADAMS/View Function Builder.

The state variable and differential equation elements do not use arrays. You reference a state variable with the VARVAL function, and reference a differential equation with the DIF and DIF1 functions. Again, for more information on these functions, see the guide, Using the ADAMS/View Function Builder.



Terminology Used in System Elements

The terminology used in the dialog boxes for creating linear state equations, general state equations, and transfer function follows standard control systems terminology, where:

■ x is the state array

■ y is the output array

■ u is the input array

■ IC is the initial conditions array, x(t=0)

You define each of these arrays using an array data element stored in the current modeling database. All array sizes must be consistent with the definition of the system elements. Do not define arrays with zero-size and zero-valued partial-derivative matrices. ADAMS/Solver correctly formulates the system equations based on those arrays and derivatives that do exist.



Defining State VariablesYou create state variables to define scalar algebraic equations for independent use or as part of the plant input, plant output, or array elements. The computed value of the variable can depend on almost any ADAMS system variable. Note that you cannot access reaction forces from point-curve and curve-curve constraints.

You use state variables in the following ways:

■ In conjunction with plant input and plant output elements to identify inputs and output for an ADAMS/Linear solution. For information on using ADAMS Linear and plant inputs and plant outputs, see the guide, Using ADAMS/Solver.

■ With array elements to identify inputs to linear state equations, general state equations, and transfer functions. See the appropriate sections in this chapter for more information on linear state equations, general state equations, and transfer functions.

■ Independently to break up long function expressions into several parts or to compute common values that you need in several other function expressions. Using state variables to compute intermediate values can make complex expressions easier to read and modify. If you use the expression in many places, computing it once in a state variable can also be faster computationally.

The next section examples more about state variables:

■ Ways to Define State Variables, 372

■ Cautions When Using State Variables, 372

■ Creating and Modifying State Variables, 373



Ways to Define State Variables

You can define the computed value of a variable by either:

■ Writing a function expression in the model.

■ Calling a VARSUB user-written subroutine.

Function expressions and user-written subroutines can access the computed value of the variable using the ADAMS/View function VARVAL(variable_name) to represent the value, where variable_name specifies the name of the variable. User-written subroutines access a single variable by calling the subroutine SYSFNC.

For more information on functions, see the guide, Using the ADAMS/View Function Builder. For more information on subroutines, see the guide, Using ADAMS/Solver Subroutines.

Cautions When Using State Variables

You should use caution when defining variables that are dependent on other variables or on ADAMS/View elements that contain functions. It is possible to create equations that cannot be solved. If a defined system of equations does not have a stable solution, convergence can fail for the entire ADAMS model.

For example, if you define your state variable my_variable using the function expression:

F=varval(my_variable) + 1

You are defining the following algebraic equation that has no solution:

V = V + 1

When ADAMS/Solver tries to solve this equation using the Newton-Raphson iteration, the solution diverges and a message appears on the screen indicating that the solution has failed to converge.



Creating and Modifying State Variables

To create and modify a state variable:

1 From the Build menu, point to System Elements, point to State Variable, and then select either New or Modify.

2 If you selected Modify, the Database Navigator appears. Select a system element to modify. For more information on the Database Navigator, see Navigating Through a Modeling Database on page 147 in the guide, Learning ADAMS/View Basics.

The Modify or Create State Variable dialog box appears. Both dialog boxes contain the same options.

3 Change the name of the state variable element, if desired.

4 From the Definition option menu, select either of the following:

■ Run-Time Expression and enter the function expression that defines the variable.

■ User Written Subroutine and enter constants to the user-written subroutine VARSUB to define a variable.

5 If desired, select Guess for F(1, 0..) and specify an approximate initial value for the variable. ADAMS/Solver may adjust the value when it performs an initial condition simulation. Entering an accurate value for initial conditions can help ADAMS/Solver converge to the initial conditions solution.



Using Differential EquationsA differential equation creates a user-defined state variable and defines a first-order differential equation that describes it. The equation can be dependent on any ADAMS/Solver state variable available in a function expression except point-curve and curve-curve constraints. You can create systems of differential equations using more than one differential equation, linear state equation, or general state equation.

You describe the variable in a differential equation either by writing a function expression or user-written subroutine. Because it is easier to write function expressions than subroutines, you should use function expressions whenever possible to describe user-defined differential variables.

The next sections give you ways to use differential equations and how to create them in ADAMS/View:

■ Ways to Define Differential Equations, 374

■ Ways You Can Use Differential Equations, 375

■ Creating and Modifying Differential Equations, 375

Ways to Define Differential Equations

You can define the differential equation in either explicit or implicit form. The following equation defines the explicit form of a differential equation:

where:

■ is the time derivative of the user-defined state variable.

■ y is the user-defined state variable itself.

■ q is a vector of ADAMS/Solver-defined state variables.

You need to use the implicit form if the first derivative of the state variable cannot be isolated. The following equation defines the implicit form of a differential equation:

y· f y q q· t, , ,( )=

y·

0 F y y· q q· t, , , ,( )=



Ways You Can Use Differential Equations

Differential equations are best for creating single equations or small sets of equations. Although you can create sets of differential equations to represent higher-order equations or large systems of equations, other ADAMS/Solver elements, such as transfer functions, linear state equations, or general state equation, can be more convenient in these cases.

You can use the solution to the differential equation in function expressions that define a number of other elements in ADAMS, such as a force, or in user-written subroutines. Both function expressions and user-written subroutines can access the user-defined state variable and its derivative. Therefore, you can use ADAMS/Solver to solve an independent initial value problem, or you can fully couple the differential equations with the system of equations that governs the dynamics of the problem.

Function expressions access the state variable using the function DIF(i1) and the derivative using DIF1(i1). In each case, i1 specifies the name of the that differential equation that defines the variable. User-written subroutines access the value and derivative by calling the subroutine SYSFNC. For more information on functions, see the guide, Using the ADAMS/View Function Builder. For more information on subroutines, see the guide, Using ADAMS/Solver Subroutines.

Creating and Modifying Differential Equations

To create or modify differential equations:

1 From the Build menu, point to System Elements, point to Differential Equation, and then select either New or Modify.

2 If you selected Modify, the Database Navigator appears. Select a differential equation to modify. For more information on the Database Navigator, see Navigating Through a Modeling Database on page 147 in the guide, Learning ADAMS/View Basics.

The Modify or Create Differential Equation dialog box appears. Both dialog boxes contain the same options.

3 Change the name of the differential equation element, if desired.



4 From the Type option menu, select either Explicit or Implicit to indicate that the function expression or subroutine defines the explicit or implicit form of the equation. For more on the forms of differential equations, see Ways to Define Differential Equations on page 374.

5 Do either of the following:

■ From the Definition option menu, select Run-time Expression, and enter a function expression that ADAMS/Solver evaluates during a simulation. In the function expression, the system variable DIF(i) is the value of the dependent variable that the differential equation defines, and DIF1(j) is the first derivative of the dependent variable that the differential equation defines.

■ User Written Subroutine and enter parameters that are passed to a user-written subroutine.

6 In the Initial Conditions text box, specify:

■ The initial value of the user-defined variable at the start of the simulation.

■ Optionally, if you are defining an implicit equation, an approximate value of the initial time derivative of the user-defined variable at the start of the simulation. (You do not need to supply a second value when you enter a explicit equation because ADAMS/Solver can compute the initial time derivative directly from the equation.)

ADAMS/Solver might adjust the value of the time derivative when it performs an initial conditions simulation. Entering an initial value for the time derivative helps ADAMS/Solver converge to a desired initial conditions solution.

7 Select whether or not ADAMS should hold constant the value of the differential equation during static and quasi-static simulations. For more information on holding the values constant, see Controlling Equilibrium Values when Using System Elements on page 369.



Defining Linear State EquationsA linear state equation defines the following linear system of first-order, explicit differential equations and algebraic equations in classical state-space form:

You specify the state variables, x, the inputs, u, and the outputs, y, using array data elements. You use a matrix data element to define the coefficient matrices A, B, C, and D. A single linear state equation can have a maximum of 1,200 inputs, 1,200 states, and 1,200 outputs. You can develop the linear state equation, arrays, and matrices manually or using other software packages.

The next sections explain different ways in which you can use linear state equations and explains how to create and modify them in ADAMS/View:

■ Ways to Use Linear State Equations, 377

■ Cautions When Using Linear State Equations, 378

■ Creating and Modifying a Linear State Equation, 378

Ways to Use Linear State Equations

Linear state equations are most useful for adding feedback control systems to your model. You can derive the A, B, C and D matrices manually or import them directly from a control system design program such as MATRIXx or MATLAB. Normally, the mechanical portion of the model includes an actuator that depends on one or more of the linear state equation outputs or states.

You can also use linear state equations to replace systems of coupled differential equations and variable elements (for nonlinear equations, you should use a general state equation). Examples of possible, dynamic-system uses include unsteady aerodynamics and electrodynamics.

x· Ax Bu+=

y Cx Du+=



Cautions When Using Linear State Equations

■ Linear state equations provide a very general capability for defining a linear element. The ADAMS/Solver integrators, however, have been developed and refined for sparse systems of equations that arise from the modeling of mechanical systems. With a linear state equation, you can create very dense sets of equations. If these equations form a large portion of your completed model, ADAMS/Solver can perform more slowly than expected.

■ Note that, if the algebraic equations defined by the linear state equation have no solution or multiple solutions (this is possible because of the general nature of the input array), ADAMS/Solver most likely fails to converge or possibly converge to an unexpected answer. To avoid this possibility, you should not reference the states (X) or outputs (Y) arrays in the variables listed in the inputs (U) array.

Creating and Modifying a Linear State Equation

To create or modify a linear state equation:

1 From the Build menu, point to System Elements, point to Linear State Equation, and then select either New or Modify.

2 If you selected Modify, the Database Navigator appears. Select a linear state equation to modify. For more information on the Database Navigator, see Navigating Through a Modeling Database on page 147 of the guide, Learning ADAMS/View Basics.

The Part Modify or Create Equation Linear State Equation dialog box appears. Both dialog boxes contain the same options.

3 Change the name of the linear state equation element, if desired, and assign a unique ID number to it. The ID is an integer used to identify the element in the ADAMS/Solver dataset (.adm) file. You only need to specify an ID number if you are exporting the model to an ADAMS/Solver dataset, and you want to control the numbering scheme used in the file.

Enter a positive integer or enter 0 to have ADAMS/View set the ID for you.



4 Add or change any comments about the equation element that you want to enter to help you manage and identify the element. You can enter any alphanumeric characters. The comments that you create appear in the information window when you select to display information about the object, in the ADAMS/View log file, and in a command or dataset file when you export your model to these types of files.

5 Enter the arrays and matrices in the next text boxes as explained below.

■ X State Array Name - Enter the array element in the current modeling database that defines the state array for the linear system. The array must be a states (X) array. It cannot be used in any other linear state equation, general state equation, or transfer function.

■ U Input Array Name - Enter the array element in the current modeling database that defines the input (or control) array for the linear system. Entering an inputs (U) array is optional. The array must be an inputs (U) array. If you enter an inputs (U) array, you must also specify either a B input matrix, a D feedforward matrix, or both. The B and D matrices must have the same number of columns as there are elements in the inputs (U) array.

■ Y Output Array Name - Enter the array element in the current modeling database that defines the column matrix of output variables for the linear system. Entering an outputs (Y) array is optional. If you enter an outputs (Y) array, you must also specify a C output matrix or a D feedforward matrix. The corresponding matrix elements must have the same number of rows as there are elements in the outputs (Y) array. It also must be an outputs (Y) array, and it cannot be used in any other linear state equation, general state equation, or transfer function.

■ IC Array Name - Enter the array element in the current modeling database that defines the column matrix of initial conditions for the linear system. Entering the IC array is optional. The must have the same number of elements as the states (X) array (equal to the number of rows in the A state matrix). When you do not specify an IC array, ADAMS/Solver initializes all states to zero.



■ A State Matrix Name - Enter the matrix data element in the current modeling database that defines the state transition matrix for the linear system. The matrix must be a square matrix (same number of rows and columns), and it must have the same number of columns as the number of rows in the states (X) array.

■ B Input Matrix Name - Enter the matrix data element in the current modeling database that defines the control matrix for the linear system. The B input matrix must have the same number of rows as the A state matrix and the same number of columns as the number of elements in the inputs (U) array.

Entering a B input matrix is optional. If you enter a B input matrix, you must also include an inputs (U) array.

■ C Output Matrix Name - Enter the matrix data element in the current modeling database that defines the output matrix for the linear system. The C output matrix must have the same number of columns as the A state matrix and the same number of rows as the number of elements in the outputs (Y) array.

Entering a C output matrix is optional. If you enter a C output matrix, you must also include an outputs (Y) array name.

■ D Feedforward Matrix Name - Enter the matrix data element in the current modeling database that defines the feed forward matrix for the linear system. The D feedforward matrix must have the same number of rows as the number of elements in the Y output array and the same number of columns as the number of elements in the inputs (U) array.

When you enter a D feedforward matrix, you must also include both a Y output matrix and an inputs (U) array.

6 From the Static Hold options menu, select yes if you do not want the linear state equation states to change during static and quasi-static simulations; select no if they can change. For more information holding values constant, see Controlling Equilibrium Values when Using System Elements on page 369.

7 Select OK.



Defining General State EquationsA general state equation defines the following set of equations consisting of explicit, first order, ordinary differential equations and algebraic equations in state-space form:

The differential equations for , and the equations for the outputs, y, are user-defined

functions of:

■ Inputs, u

■ State variables, x

■ Time, t

You define the equations, differential and algebraic, using array data elements and user-written subroutines. Note that the general state equations for nonlinear systems are analogous to linear state equations for linear systems. A single general state equation can have a maximum of 1,200 inputs, 1,200 states, and 1,200 outputs.

Note that a system that a general state equation defines is restricted to explicit functions of the states and inputs. The state variables, however, included in the outputs (U) array can be completely general. You can write general state equations that depend on any available state variable.

The current values for the state derivatives and output arrays of the general state equation are computed in the user-supplied GSESUB subroutine, the same as for any other user-written subroutine. Additionally, you must provide GSEXX, GSEXU, GSEYX, and GSEYU subroutines to compute the necessary internal partial derivatives. For more information, see the guide, Using ADAMS/Solver Subroutines.

The next sections explain more about general state equations:

■ Ways to Use General State Equations, 382

■ Cautions When Using General State Equations, 382

■ Creating and Modifying General State Equations, 383

x· f x u t, ,( )=

y g x u t, ,( )=

x·



Ways to Use General State Equations

General state equations are most useful for adding nonlinear or time-varying feedback controls to a model as part of an overall control system design problem using such programs as MATRIXx or MATLAB. Normally, the mechanical portion of the model includes an actuator that depends on one or more of the general state equation outputs or states. Using the GSESUB subroutine, you can incorporate scheduled gains, parametric dependencies, or even adaptive algorithms.

You can also use general state equations to replace arbitrary systems of nonlinear or parametric, coupled differential equations and variables (for linear, time-invariant equations, you should use linear state equations instead). Note that apart from the convenience, general state equations have no computational advantage over the differential equations and variables. Examples of possible non-control system uses of general state equations include unsteady aerodynamics and hydrodynamics, elastomerics, hydraulics, power transmission, and electrodynamics.

Cautions When Using General State Equations

General state equations provide a very general capability for modeling nonlinear systems. However, the routines for solving the linear equations in ADAMS/Solver have been developed and refined to work particularly well with the sparse systems of equations that come from the assembly of mechanical models. With general state equations, you can create very dense sets of equations. If these equations form a large portion of the completed model, ADAMS/Solver can perform more slowly than expected.



Creating and Modifying General State Equations

To create or modify a general state equation:

1 From the Build menu, point to System Elements, point to General State Equation, and then select either New or Modify.

2 If you selected Modify, the Database Navigator appears. Select a system element to modify. For more information on the Database Navigator, see Navigating Through a Modeling Database on page 147 of the guide, Learning ADAMS/View Basics.

The Part Modify or Create Equation General State Equation dialog box appears. Both dialog boxes contain the same options.

3 Change the name of the general state equation element, if desired, and assign a unique ID to it. The ID is an integer number used to identify the element in the ADAMS/Solver dataset (.adm) file. You only need to specify an ID if you are exporting the model to an ADAMS/Solver dataset, and you want to control the numbering scheme used in the file.

Enter a positive integer or enter 0 to have ADAMS set the ID for you.

4 Add or change any comments about the equation element that you want to enter to help you manage and identify the element. You can enter any alphanumeric characters. The comments that you create appear in the information window when you select to display information about the object, in the ADAMS/View log file, and in a command or dataset file when you export your model to these types of files.

5 In the State Equation Count and Output Equation Count text boxes, enter the number of state equations (differential variables) that are used in the definition of

= f (x, u, t) and the number of output equations (algebraic variables) that

are used in the definition of y = g (x, u, t). There must be at least one state equation in your general state equation. If you specify an output equation count greater than 0, then you must specify an outputs (Y) array.

x·



6 Enter the arrays and matrices in the next text boxes as explained in the list below:

■ X State Array Name - Enter the array element in the current modeling database that defines the state variables for the general state equation. The array must be an state (X) array, and cannot be used in any other linear state equation, general state equation, or transfer function. If you specified the size of the array when you created it, you must make its size the same as the number of state equations you specified in the State Equation Count text box.

■ U Input Array Name - Enter the array element in the current modeling database that defines the input (or control) variables for the general state equation. Entering a inputs (U) array is optional. If you do not enter an inputs (U) array, there are no system inputs. The array must be an inputs (U) array, and you must also specify the Df Du Method or Dg Du Method, or both. ADAMS/Solver infers the number of inputs to the general state equation from the number of variables in the inputs (U) array.

■ Y Output Array Name - Enter the array element in the current modeling database that defines the output variables for the general state equation. You only need to enter an outputs (Y) array if the number of output equations is greater than 0. Otherwise, there are no outputs for the system.

If you enter an outputs (Y) array, the array must be an output (Y) array. It also cannot be used with any other linear state equation, general state equation, or transfer function. You must also set the Dg Dx Method or Dg Du Method, or both, to USER. If you specified the size of the array when you created it, its size must be the same as the number of output equations that you entered in the Output Equation Count text box.

■ IC Array Name - Designates the array data element in the current modeling database that defines the initial conditions array for this system element. Entering the initial conditions array is optional. If you enter an initial conditions array, it must be of an IC array, and it must have the same number of elements as the states (X) array. If you do not enter an IC array, ADAMS/Solver initializes all states to zero.



7 From the option menus, set how you want ADAMS to compute the matrices as explained below. For more information on subroutines, see the guide, Using ADAMS/Solver Subroutines.

■ Df Dx Method - Determines how to compute the matrix of partial derivatives of the state equations with respect to the states. The possible value for this flag is USER, meaning that you must provide a GSEXX subroutine to return the current values of these partial derivatives.

■ Df Du Method - Determines how to compute the matrix of partial derivatives of the state equations with respect to the inputs. The possible values for this flag are USER and NONE. USER means that you must provide a GSEXU subroutine to return the current values of these partial derivatives, and NONE means that the state equations do not depend on the inputs.

■ Dg Dx Method - Determines how to compute the matrix of partial derivatives of the output equations with respect to the states. The possible values for this flag are USER and NONE. USER means that you must provide a GSEYX subroutine to return the current values of these partial derivatives, and NONE means that the output equations do not depend on the states.

■ Dg Du Method - Determines how to compute the matrix of partial derivatives of the output equations with respect to the inputs. The possible values for this flag are USER and NONE. USER means that you must provide a GSEYU subroutine to return the current values of these partial derivatives, and NONE means that the output equations do not depend on the inputs.

8 From the Static Hold option menu, select yes to indicate that the general state equation states are not permitted to change during static and quasi-static simulations. Select no if they can change. For more information on static hold, see Controlling Equilibrium Values when Using System Elements on page 369.

9 In the User Function text box, enter parameters to a user-written subroutine. ADAMS/View passes these values to your user subroutines.

You can define up to thirty constants that are passed to the user-written GSESUB subroutine that determines the current values of the state derivatives and outputs forming this general state equation. They are also passed to the partial derivative evaluation subroutines, GSEXX, GSEXU, GSEYX, and GSEYU.

10 Select OK.



Defining Transfer FunctionsYou can use transfer functions to define an arbitrary set of constant-coefficient, differential and algebraic equations that can be expressed in the Laplace domain as the following where m ≤ k:

Transfer functions are especially useful for describing elements from control-system block diagrams. The characteristic equation for a single transfer function can be a polynomial of degree less than 30.

Internal to ADAMS/Solver, there is an algorithm to automatically convert the list of fixed numerator and denominator coefficients to the following elements:

■ Canonical state-space form.

■ Set of coupled, linear, constant-coefficient differential equations.

■ Single algebraic equation.

You define the arrays for a transfer function using array data elements. The arrays define the transfer function input and let you reference the states and output of the transfer function. Initial conditions for a transfer function are assumed to be identically zero.

The next sections explain more about transfer functions:

■ Understanding the Details of Transfer Functions, 387

■ Creating and Modifying Transfer Functions, 389

G s( ) y s( )u s( )----------

b0 b1s1 … bms

m+ + +

a0 a1s1 … aks

k+ + +

-------------------------------------------------------= =



Understanding the Details of Transfer Functions

When you reference only the output of the transfer function, the details of the internal equations are unimportant. In some cases, however, it may be useful to understand how ADAMS/Solver constructs the equations. When interpreting ADAMS/Linear output or examining the values in the states (X) array, for instance, it may be necessary to determine what the internal states represent.

ADAMS/Solver performs the conversion from transfer function to canonical state-space form in two steps. First, it normalizes the numerator and denominator by the coefficient of the largest power of s in the denominator.

where array p is of length k+1. Array q is also of length k+1, padded with zeros, if necessary. The entries in arrays p and q are labeled from 0 to k for the following analogous transfer function:

The equivalent state space realization of this transfer function is:

q b0 ak b1 ak … bm ak 0 … 0 0, , , ,⁄, ,⁄,⁄[ ]=

p a0 ak a1 ak … ak 1– ak 1,⁄, ,⁄,⁄[ ]=

G s( ) y s( )u s( )----------

q0 q1s1 … qks

k+ + +

p0 p1s1 … pks

k+ + +

----------------------------------------------------= =

xy

A BC D

xu{ } =

{ }



where:

Note that except in the specific case where the numerator and denominator are of equal orders, qk = 0.

A

p

p

p

p

B

q p q

q p q

=

−−

−−

=

−−

−

−

− −

− −

k

k

k k k

k k k

1

2

1

0

1 1

2 2

1 0 0 0

0 1 0 0

1

1

0 0 0 1

0 0 0 0

. . .

. . .

• . . . . . .

• . . . . . . .

• . . . . . .

. . .

. . .

•

••

•

. . .

q p q

q p q

C D q

1 1

0 0

1 0 0 0 0

−−

= [ ] = [ ]

k

k

k



Creating and Modifying Transfer Functions

To create or modify a transfer function:

1 From the Build menu, point to System Elements, point to Transfer Function, and then select either New or Modify.

2 If you selected Modify, the Database Navigator appears. Select a system element to modify. For more information on the Database Navigator, see Navigating Through a Modeling Database on page 147 of the guide, Learning ADAMS/View Basics.

The Modify or Create Transfer Function dialog box appears. Both dialog boxes contain the same options.

3 Change the name of the transfer function element, if desired.

4 Enter the arrays for the transfer function in the next three text boxes as explained below:

■ Input Array Name (U) - Enter the array that defines the input (or control) for the transfer function. The array must be an inputs (U) array. If you specified the size of the array when you created it, it must be one.

■ State Array Name (X) - Enter the array that defines the state variable array for the transfer function. The array must be a states (X) array, and it cannot be used in any other linear state equation, general state equation, or transfer function. If you specified the size of the array when you created it, it must be one less than the number of coefficients in the denominator.

■ Output Array (Y) - Enter the array that defines the output for the transfer function. The array must be an outputs (Y) array, and it cannot be used in any other linear state equation, general state equation, or transfer function. If you specify the size of the array when you created it, its size must be one.



5 In the Denominator Coefficients and Numerator Coefficients text boxes, specify the coefficients of the polynomial in the denominator and numerator of the transfer function. List the coefficients in order of ascending power of s, starting with s to the zero power, including any intermediate zero coefficients. The number of coefficients for the denominator must be greater than or equal to the number of coefficients for the numerator. The number of coefficients for the denominator must be greater than or equal to the number of coefficients for the numerator.

6 Select whether or not ADAMS/Solver should hold constant the states of the transfer function during static and quasi-static simulations. For more information on holding state values constant, see Controlling Equilibrium Values when Using System Elements on page 369.

7 Select OK.

11 Editing Modeling Objects

OverviewOnce you’ve created modeling objects, you can easily modify them. You modify all modeling objects using the same set of tools and commands. This chapter explains how to edit modeling objects. It contains the sections:

■ Selecting and Deselecting Objects, 392

■ Editing Objects Using the Table Editor, 401

■ Accessing Modify Dialog Boxes, 420

■ Copying Objects, 421

■ Deleting Objects, 423

■ Renaming Objects, 425

■ Activating and Deactivating Objects, 427

■ Grouping and Ungrouping Objects, 431

■ Setting Object Appearance, 433

■ Setting Object Colors, 436


Editing Modeling Objects392

Selecting and Deselecting ObjectsWhen you create a modeling object, such as a part or force, ADAMS/View automatically selects it so that you can edit it. When you create a rigid body, hotpoints and an object position handle appear on the body so that you can rotate and position the body’ s geometry. (For information on using hotpoints, see Modifying Rigid Body Geometry on page 80. For information on the object position handle, see Translating and Rotating Objects Using Position Handle on page 443.)

You can also select objects for editing. You can select one or more objects or select a group of objects based on their type, such as select all link geometry. The next sections explain how to select objects.

■ Selecting One Object, 393

■ Selecting Several Objects, 394

■ Selecting Objects from a Crowd, 395

■ Deselecting Objects, 395

■ Managing the List of Selected Objects, 396



Selecting One Object

You can select any modeling object, such as a part or force. Selecting the object deselects any currently selected object. If you select a rigid body, ADAMS/View selects the entire body including its geometry. You can select objects using the Select tool on the Main toolbox or using the pop-up menu that appears when you hold down the right mouse button over any object.

To select a single object using the Select tool:

1 From the Main toolbox, select the Select tool .

2 Click anywhere on the object.

The object appears with a thicker line width. If the object is a rigid body, its hotpoints and object position handle appear on the body so that you can rotate and position the body’s geometry.

To select a single object using the pop-up menu:

1 Place the cursor over the object that you want to select.

2 Click and hold down the right mouse button.

A pop-up menu appears.

3 Point to the object name and then select Select.

The object appears with a thicker line width. If the object is a rigid body, its hotpoints and object position handle appear on the body so that you can rotate and position the body’s geometry.



Selecting Several Objects

You can use a rectangular selection box to select more than one modeling object. ADAMS/View selects any object that the box completely or partially encloses. It deselects any currently selected objects.

To select objects using a selection box:

1 From the Main toolbox, select the Select tool .

2 Position the cursor on the screen where you want a corner of the selection box and drag the mouse to draw a rectangle that encloses or touches the objects that you want to select.


The selected objects appear with a thicker line width. If the object is a rigid body, its hotpoints and the object position handle appear on the body so that you can rotate and position the body’ s geometry.

Figure 99. Selecting Objects Using Selection Box

Drawing this selection box...

This object selected even though notentirely in box

Selects these objects

y

z xy

z x

y

zx

y

zx

y

zx

y

zx

y

zx

y

zx

y

z xy

z x



Selecting Objects from a Crowd

When you are performing an operation, such as setting an object’ s appearance, and you need to select an object from the screen but the object is obscured by other objects, you can display a list of all objects in that area and then select the desired object from the list. Note that this only works during a modeling operation.

To display a list of all objects in an area of the screen:

1 Press the Ctrl key and click the right mouse button when the cursor is the area of the screen containing the desired object.

A selection box of all the objects in the area appears.

2 Highlight the desired object from the list and select OK.

Deselecting Objects

To deselect objects:

■ To deselect an object, click when the cursor is anywhere on the background of the screen.



Managing the List of Selected Objects

You can use the Select List Manager to view objects you’ve selected using the procedures explained in the previous sections and add to and remove objects from the select list. You can add and remove objects based on their name, type, group, and parent.

The next sections explain how to use the Select List Manager:

■ Displaying the Select List Manager, 397

■ Adding a Single Object to the Select List, 397

■ Adding or Removing Objects, 398

■ Updating the Select List Display, 400



Displaying the Select List Manager

To display the Select List Manager:

■ From the Edit menu, select Select List. The Select List Manager appears.

The current objects in the select list appear in the Select List Manager window. Refer to the next sections for information on using the Select List Manager to manage the objects in the list.

Adding a Single Object to the Select List

To add a single object to the select list:

■ In the Object Name text box, enter the name of the object that you want to add, and then select the Add button next to the text box.

To search for or select an object from the screen, place the cursor in the Object Name text box and hold down the right mouse button. From the pop-up menu that appears, select Browse or Select.

Current objectsin select list



Adding or Removing Objects

You can add multiple objects to or remove multiple objects from the select list by selecting the desired objects or by setting up search criteria based on an object’s name, type, such as geometry, group, or parent. ADAMS/View gives you the flexibility to:

■ Broaden the search for objects to be included or removed by entering wildcards. You can specify, for example, to remove all objects that contain a particular character, such as an h. For more on wildcards, see Using Wildcards on page 161 of the guide, Learning ADAMS/View Basics.

■ Limit the scope of the objects to be added or removed to only objects that belong to a particular object in the modeling database. For example, you can tell ADAMS/View to limit the scope from all markers to only markers belonging to a PART_1.

To add or remove multiple objects to and from the select list based on search criteria:

1 In the Name Filter text box, enter the name of the objects that you want to add to or remove from the select list. Type any wildcards that you want included.

2 Set the Type Filter option menu to the type of object or objects that you want to add or remove. To display all the different object types, select Browse from the option menu.

3 In the Scope text box, limit the scope of objects to be added or removed to only objects belonging to a certain object by entering the name of the parent object.

To select an object on the screen or browse for an object in the Database Navigator, right-click the text box, and then select the appropriate command.

4 Select Add or Remove.



To remove selected objects from the list:

1 Select Remove Objects.

A list of currently selected objects appears.

2 Select the object or objects to remove as explained next.

■ To select a single object, click the object.

■ To use the mouse to select a continuous set of objects, drag the mouse over the objects that you want to select or click on one object, hold down the Shift key, and click the last object in the set. All objects between the two selected objects are highlighted.

■ To use the up and down arrow keys to select a continuous set of objects, click on the first object, hold down the Shift key, and then use the up or down arrow to select a block of objects.

■ To select a noncontinuous set of objects, click on an object, hold down the Ctrl key, and click on the individual objects that you want.

■ To clear any object in the selected list, hold down the Ctrl key and then click the selected object to clear its highlighting.

3 Select OK.

To quickly remove all objects from the list:

■ Select Clear All.



Updating the Select List Display

You can update the list of objects in the Select List Manager window so that it reflects any selections that you made using the mouse or pop-up menus as explained in the previous sections.

To update the select list display:

■ Select Refresh.

Selecting Objects in a Group

You can add to or remove objects in a group to the Select List Manager just as you would for any type of object as explained in Adding or Removing Objects on page 398. Before adding the object to the select list, you can set whether or not you want to list each object in the group in the Select List Manager or just list the name of the group.

To list all objects in a group in the Select List Manager:

■ Select Expand Groups.



Editing Objects Using the Table EditorThe Table Editor is a convenient way to manage the objects in your model. It displays the objects in your modeling database in table format so you can compare the objects and quickly update them. For example, you can update the x, y, and z locations of all parts in your model at once or parameterize the locations of parts to the locations of other parts. The information that you can view and update about an object depends on the type of object. The Table Editor also lets you create and delete objects.

The next sections explain how to work with the Table Editor.

■ Displaying the Table Editor, 402

■ Viewing Objects in the Table Editor, 403

■ Working with Objects, 411

■ Working with Cells, 414

■ Reloading Database Values, 418

■ Applying Changes, 418

■ Saving Table Editor Information, 419

For general information on using tables in ADAMS/View, see Using Tables to Enter Values on page 77 in the guide, Learning ADAMS/View Basics.



Displaying the Table Editor

To display the Table Editor:

■ From the Tools menu, select Table Editor.

The Table Editor appears, as shown below.

Figure 100. Table Editor

Input boxPerform operationson multiple cells

Set object display

Cell

Row

Column header

Lock

header

button



Viewing Objects in the Table Editor

By default, the Table Editor displays the x, y, and z location of parts in your model. You can change the type of object displayed, as well as set the categories of information displayed about the objects. For example, you can change the objects displayed to coordinate system markers and display the comments associated with the markers or their locations relative to ground. You can also sort the information, resize the columns so you can more easily view the information, and update the display of the Table Editor. The next sections explain how to view objects in the Table Editor:

■ Setting Types of Objects Displayed, 404

■ Setting Filters for Standard Objects, 407

■ Sorting Objects in the Table Editor, 410

■ Working with Objects, 411

■ Reloading Database Values, 418



Setting Types of Objects Displayed

You can display any type of object that is in your current modeling database through the Table Editor. For example, you can select to view all coordinate system markers or all motions. You can only view one type of object at a time.

ADAMS/View provides option buttons for selecting the most common modeling objects. The option buttons appear along the bottom of the Table Editor. You can also view non-standard modeling objects, such as splines or interface objects. As you select to view a non-standard object type, you can also narrow the display of objects based on the object’s name or parent.

Note: Be careful when you select a non-standard type of object because the object information may not be appropriate for editing in the Table Editor. For example, you can select to display information about the view layouts in your main window, which are not appropriate for editing in table format. You may receive error messages if you select to edit or create an object of a non-standard type through the Table Editor.

To set the type of objects displayed to a standard type:

■ Select a check box of the desired object type from along the bottom of the Table Editor.

ADAMS/View updates the Table Editor to display the selected type of object.

Tip: If you do not see any objects in the Table Editor, the filter may not be set correctly for the type of object you selected. For example, by default, the filter for joints is set to only display revolute joints. Therefore, if you have no revolute joints in your model, you will not see any joints displayed in the Table Editor when you select Joints as the type of object. For more information on setting filters, see Setting Filters for Standard Objects on page 407.



To set the type of objects displayed to a non-standard object:

1 Along the bottom of the Table Editor, select Anything.

2 Select Filters.

The Anything Table Editor Filters dialog box appears.

3 In the Scope text box, limit the scope of the search, if desired, to all objects beneath a particular object in the database hierarchy by entering the name of the object.

Tip: For more information on entering information in this text box, see Setting Filters for Standard Objects on page 407.

4 In the Name Filter text box, enter the name of the object or objects that you want to display. Type any wildcards that you want included. By default, ADAMS/View displays all objects that meet the search criteria regardless of their name. For more on wildcards, see Using Wildcards on page 161 of the guide, Learning ADAMS/View Basics.

Tip: For more information on entering information in this text box, see Setting Filters for Standard Objects on page 407.

5 In the Entity type text box, enter the type of object you want displayed in the Table Editor. To select a category of object from a list, select Select. You can only select one object category.

6 In the Object Fields text box, select the type of information you want displayed about the objects. To select information categories from a list, select Select. You can select more than one category.

7 Select OK.

Example: Figure 101 on page 406 shows an example of displaying information about beams, which are non-standard objects. In the example, you first select Anything and then Filters at the bottom of the Table Editor. When the Anything Table Editor Filters dialog box appears, you set the Entity type to Beam and then select four fields of information to display about beams. The result in the Table Editor is a listing of five beams.



Figure 101. Using the Anything Filter

1 At the bottom of the Table Editor, select Anything, and then Filters.

2 Enter values in the Anything Table Editor Filters dialog box.

Your results are:



Setting Filters for Standard Objects

You can filter the categories of information that the Table Editor displays about standard types of objects, such as markers. You can also select a type of joint or force about which you want to display information.

You can also narrow the display of objects based on an object’s name or parent, such as to display only markers that belong to PART_1, which is called setting the scope. You can also narrow the display based on the names of objects. For example, you can set the name filter to only display the names of objects that contain the number 2 (MARKER_20, MARKER_21, and so on). Using the scope and name filter together, you can focus on those objects of interest and filter out the rest.

Note: For non-standard object types, you filter the information categories displayed and narrow the number of objects displayed as you select the non-standard object type to be displayed. For information, see Setting Types of Objects Displayed on page 404.

The categories of information that you can display about an object depend on the type of object. For example, for parts, you can display their location, initial conditions, and attributes, such as whether they are visible or active in the current simulation. For markers, you can view their locations, as well as their locations relative to ground. For forces, you cannot change the information displayed, only the types of forces displayed. For joints, you can change the information displayed as well as the type of joints displayed.

To filter the information displayed in the Table Editor:

1 Set the type of object displayed to a standard object as explained in Setting Types of Objects Displayed on page 404.

2 Select Filters from the Table Editor.

A filters dialog box appears. The options in the dialog box depend on the type of object currently displayed.



3 In the Scope text box, limit the scope of the search, if desired, to all objects beneath a particular object in the database hierarchy by entering the name of the object. Note that you cannot enter wildcards in the Scope text box.

For example, enter .model_1 to display all objects under your entire model or enter .model_1.PART_3 to display objects belonging only to PART_3.

4 In the Name Filter text box, enter the name of the object or objects that you want to display. Type any wildcards that you want included. By default, ADAMS/View displays all objects that meet the scope entered in the previous step regardless of their name. For more on wildcards, see Using Wildcards on page 161 of the guide, Learning ADAMS/View Basics.

For example, enter the following to display all markers whose names start with MARKER_2 or MARKER_3 (MARKER_20, MARKER_30, MARKER_31, and so on).

MARKER_[23]*

5 Select the categories of information or set the type of object that you want displayed and select OK.

Example: Figure 102 on page 409 shows an example of displaying information about markers. In the example, you first select Markers from the bottom of the Table Editor. When the Markers Table Editor Filters dialog box appears, you set the types of information to display about markers. The result in the Table Editor is a listing of six markers.



Figure 102. Using the Marker Filter

1 At the bottom of the Table Editor, select Markers and then Filters.

2 Enter values in the Marker Table Editor Filters dialog box.

Your results are:



Sorting Objects in the Table Editor

After you’ve set up the type of objects and categories of information you want displayed, you can sort the information. You can sort the information by object name or by a particular column. You can also set the type of sorting. You can select:

■ Alphanumeric sorting, which sorts the information so that alphabetic characters are first followed by numeric characters.

■ Numeric sorting, which sorts objects based on their numeric value. It sorts any alphabetic characters as zeros.

Note: When you sort the Table Editor, ADAMS/View sets the values displayed in cells back to those stored in the modeling database. Therefore, you lose any changes that you made to cells and did not apply to your modeling database.

To sort objects in the Table Editor:

1 Select Sorting in the Table Editor.

The Sorting Settings dialog box appears.

2 Set the sorting options as explained in Table 47 and select OK.

Table 47. Sorting Options

To set: Select one of the following:

The category on which objects are sorted

■ No sorting - Objects appear in the Table Editor in the order they are stored in the modeling database.

■ Sort By Name - Sorts the objects by their name (by rows).

■ Sort By Column Labelled and enter the name of the column on which to sort the objects. To select a column name from a list, select Select.

Sort order ■ Alphabetic to sort alphabetic characters first.

■ Numeric to sort in numeric order. It sorts any alphabetic characters as zeros.



Working with Objects

Using the Table Editor, you can copy, create, and delete objects in your modeling database. The next sections explain how to work with objects using the Table Editor.

■ Copying Objects, 411

■ Creating Objects, 412

■ Deleting Objects, 413

Note: The operations you perform with the Table Editor are not stored in your modeling database until you apply them. For more information on applying changes, see Applying Changes on page 418.

Copying Objects

You can create a new object by copying an existing object. ADAMS/View assigns the new object a default name and displays its information in the last row of the Table Editor.

To copy an object:

1 Select the row containing the object you want to copy.

2 Right-click a cell in a row that is not selected. From the pop-up menu that appears, select Copy Object.

ADAMS/View creates a duplicate of the object. It places the object in the last row of the Table Editor.



Creating Objects

Using the Table Editor, you can create certain types of modeling objects. For most types of objects, you can only create an object if another object of that type already exists in the modeling database. For example, if the Table Editor is set to display forces but you currently have no forces in your modeling database, you cannot create a force through the Table Editor.

You can create parts, points, and coordinate system markers, however, regardless of whether or not an object of that type already exists in the modeling database. For example, you can create a new marker if the Table Editor is set to display coordinate system markers. You do not have to have an object of this type already in the database.

Note that you cannot create a joint through the Table Editor.

To create a part, marker, or point with default values:

1 Display parts, markers, or points in the Table Editor. For information on setting the type of object displayed in the Table Editor, see Viewing Objects in the Table Editor on page 403.

2 Select the Create button along the bottom of the Table Editor.

ADAMS/View creates an object with default values. It displays the object’s information in the last row of the Table Editor.

To create other types of objects:

1 Display the type of object you want to create in the Table Editor. For information on setting the type of object displayed in the Table Editor, see Viewing Objects in the Table Editor on page 403. An object of the type to be created must already exist in the database.

2 Right-click a cell that is not selected. From the pop-up menu that appears, select Create Object.

ADAMS/View displays a dialog box that helps you create the object.

3 Enter the values in the dialog box and select OK.



Deleting Objects

You can delete any object in the modeling database using the Table Editor. Be careful, however, when you delete non-standard objects, such as view layouts or interface objects. Deleting a non-standard object may have more consequences that you are not aware of.

To delete an object:

1 Select the row containing the object you want to delete.

2 Right-click a cell in the row. From the pop-up menu that appears, select Delete Object.

ADAMS/View deletes the object from the Table Editor.



Working with Cells

The cells of the Table Editor display information about the objects in your modeling database. You can modify the information displayed about objects to make changes to the objects in the modeling database. For example, you can move a point by changing its x location in the Table Editor from 50 inches to 60 inches. The next sections explain how to modify the information displayed in the cells of the Table Editor.

■ Entering Text in Cells, 415

■ Inserting Text into a Multiple Cells, 415

■ Entering Object and Information Names in Cells, 416

■ Modifying Cells Based on Their Current Contents, 417

Note: The operations you perform with the Table Editor are not stored in your modeling database until you apply them. For more information on applying changes, see Applying Changes on page 418.



Entering Text in Cells

While you can enter text directly into the cells of the Table Editor, you can also use the input box that appears at the top of the Table Editor. The input box lets you add text to more than one cell at a time and quickly update the values in the cell. For an illustration of the input box, see Figure 100 on page 402.

To enter text in a cell:

1 Click the cell. The text cursor appears in the cell.

2 Type the text you want.

To enter text through the input box:

1 Click the cell whose text you want to edit.

The text in the cell appears in the input box.

2 Place the cursor in the input box and type the text you want.

3 To insert the text in the input box into the cell, do either of the following:

■ Select the Lock tool .

■ Press Enter.

Inserting Text into a Multiple Cells

You can use the input box to insert the same text into multiple cells at once.

To insert text into multiple cells:

1 Select the cells in which you want to insert the text as explained in Selecting Cells and Rows on page 79 of the guide, Learning ADAMS/View Basics.

2 In the input box, enter the text that you want to insert as explained in Entering Text in Cells on page 415.

3 Select the Insert tool .



Entering Object and Information Names in Cells

When you create function expressions or parameterize your model, you often need to include the full name of a modeling object, which is the name of the object’ s parent followed by the object’ s name, and the name assigned to the information you want associated with the object as it appears in the modeling database. For example, when building a function for a force, you often refer to a marker’ s displacement in the x direction. In a function expression, you enter the following:

.model_1.PART_2.MAR_1.Loc_X

The Table Editor provides a shortcut for entering the object and field names so that you can build functions and parameterize your model quickly.

To quickly enter an object’s full name and information field into the input box:

1 Place the cursor in the input box where you want the object name to be inserted.

2 Select the Object Name & Field tool f(x) on the Table Editor.

3 Select any cell in the row containing the object whose name you want to input.

ADAMS/View inserts the object’s full name and field information into the cell.

For more information on building functions, see the guide, Using the ADAMS/View Function Builder. For information on parameterizing your model, see Automating Design Changes Using Parameterization on page 13 of the guide, Refining Model Designs in ADAMS/View.



Modifying Cells Based on Their Current Contents

Using the Table Editor, you can quickly update the current value in many cells at once. For example, you can update the x location of all markers to be that of their current location plus 3. The Table Editor creates a variable based on the current contents of a cell ($cell), which you can use to update the cells.

For a marker example, the Table Editor would create a text string in the input box that represents the current x location of all selected markers. You would then create an expression to add 3 to any current cell value. The input box would look like the following:

$cell + 3

When you insert the expression into the x location cell of a selected marker, the variable changes to the current value of the selected cell. For the marker example, the cell for MARKER_1 whose current value is 20, now looks like the following:

(20 + 3)

When you apply the changes to the modeling database, ADAMS/View stores the value as an expression (an expression in ADAMS/View always is enclosed in parenthesis ( )):

(20 + 3)

To have ADAMS/View evaluate the expression and store only a number, enter eval in front of the expression in the input box as shown below and then insert the expression to the cells:

eval($cell + 3)



To modify the cells based on their current contents:

1 Display the type of object you want to update in the Table Editor, if necessary. For information on setting the type of object displayed in the Table Editor, see Viewing Objects in the Table Editor on page 403.

2 Select the cells you want to update as explained in Selecting Cells and Rows on page 79 of the guide, Learning ADAMS/View Basics.

3 Enter how you want to update the cells in the input box as explained in

Entering Text in Cells on page 415. Select the Cell Variable tool to create a variable representing the current contents of the cells.

4 Select the Insert tool .

ADAMS/View updates the cells with the information in the input box.

Reloading Database Values

If you have made changes to values in a table that you would like to clear out and reset to the current values of the object, you can reload the table.

To reload the Table Editor:

■ Select Reload.

Applying Changes

You must apply any changes you make to objects in the Table Editor before ADAMS/View saves them in the modeling database.

To apply changes:

■ From the Table Editor, select Apply.



Saving Table Editor Information

You can save the current contents of the Table Editor in ASCII format. ADAMS/View places spaces between each cell.

To save the current contents:

1 From the Table Editor, select Write.

The File Selection dialog box appears.

2 In the Directories list box, select the directory in which you want the file located.

3 In the Selection text box, enter the file name.

4 Select OK.



Accessing Modify Dialog BoxesTo change the properties for an object in ADAMS/View, you use the modify dialog box associated with the object. For example, you modify a simple idealized joint using the Modify Joint dialog box. Follow the instructions below to learn how to display a modify dialog box and follow the instructions in the appropriate sections of this guide to learn how to modify a particular type of object using the dialog box.

To display a modify dialog box for an object on the screen:

■ Right-click the object whose properties you want to modify, point to the type of object, and then select Modify. For example, for a joint, the pop-up menu displays the word Joint. You would point to Joint, and then select Modify.

Tip: You can zoom in on the object on the screen to more easily place the cursor over just that object. For more on zooming objects, see Zooming the Model Display on page 107 of the guide, Learning ADAMS/View Basics.

The modify dialog box appears.

Shortcut: Double-click the object to display its modify dialog box or select the object and then enter Ctrl + e.

To use the Database Navigator to display a modify dialog box:

1 Double-click the background of the ADAMS/View main window to clear any selections.

2 From the Edit menu, select Modify.

The Database Navigator appears. It displays the models in your current database.

3 Select the object whose properties you want to modify. For information on selecting objects in the Database Navigator, see Navigating Through a Modeling Database on page 147 of the guide, Learning ADAMS/View Basics.

4 Select OK.

The modify dialog box appears.



Copying ObjectsYou can copy any selected objects within the same model. ADAMS/View creates an identical copy of the selected object. ADAMS/View assigns a default name to the duplicated object using the copied object name as the base name and appending _2 to the name. For example, if ADAMS/View copies a rigid body called PART_1, it assigns the new object the name PART_1_2.

To copy selected objects:

1 Select the objects that you want to copy. For information on selecting objects, see Selecting and Deselecting Objects on page 392.

2 Select one of the following:

■ From the Edit menu, select Copy.

■ From the Standard toolbar, select the Copy tool .

ADAMS/View creates a copy of the objects. It selects the copied objects so you can edit or move them.

Shortcut: Select Ctrl + C.



To copy an object on the screen using the pop-up menu:

1 Right-click the object you want to copy.


2 From the pop-up menu that appears, select Copy.

To copy objects using the Database Navigator:

1 To clear any selections, click the background of the ADAMS/View main window.

2 From the Edit menu, select Copy.

The Database Navigator appears with the current models in your modeling database listed.

3 Select the object you want to copy. For more on selecting objects from the Database Navigator, see the section, Navigating Through a Modeling Database on page 147 of the guide, Learning ADAMS/View Basics.

4 Select OK.



Deleting ObjectsYou can delete any object that you created in the current modeling database, including deleting a model. For more information on the effects of deleting a model, see Deleting a Model on page 170 of the guide, Learning ADAMS/View Basics.

You can delete any object that has a graphical representation on the screen, such as a rigid body or link, by selecting them first and then deleting them. You can also select objects that do not have graphical representations by searching for them through the Database Navigator and then deleting them.

To delete selected objects:

1 Select the objects that you want to delete. For information on selecting objects, see Selecting and Deselecting Objects on page 392.

2 From the Edit menu, select Delete.

3 ADAMS/View deletes the selected objects.

Shortcut: Select the Del. key.

To delete an object on the screen using the pop-up menu:

1 Right-click the object you want to delete.


2 From the pop-up menu that appears, select Delete.



To delete objects using the Database Navigator:


2 From the Edit menu, select Delete.


3 Select the object you want to delete from the Database Navigator. For more on selecting objects from the Database Navigator, see Working with Models on page 163 of the guide, Learning ADAMS/View Basics.

4 Select OK.



Renaming ObjectsAs you create objects in ADAMS/View, ADAMS/View automatically assigns names to them. The name consists of the type of object and a unique ID. For example, it names a joint JOINT_1 and a motion MOTION_1.

An object also has a full name, which is the name of the object’ s parent followed by the name of the object. A full name always begins with a “ .” (dot). For example, a part with the name PART_1 in the model SLA has the full name .SLA.PART_1.

Objects must have a unique name relative to other objects that belong to their parents. For example, you cannot have two points named PT1 on part PART_1, but you can have PT1 on more than one part because the full names of each point would be unique (.SLA.PART_1.PT1 and .SLA.PART_2.PT1.)

ADAMS/View allows you to change the default name assigned to any object but you cannot change its full name. ADAMS/View often shows you just the name of the object and not its full name to simplify the display of objects.

To rename a selected object:

1 Select the object that you want to rename. For information on selecting objects, see Selecting and Deselecting Objects on page 392.

2 From the Edit menu, select Rename.

The Rename Object dialog box appears.

3 In the New Name text box, enter the name you want to assign to the object.

4 Select OK.



To rename an object on the screen using the pop-up menu:

1 Right-click the object you want to rename.


2 From the pop-up menu that appears, select Rename.



4 Select OK.

To rename any object in the database:


2 From the Edit menu, select Rename. The Database Navigator appears.

3 Select the object that you want to rename from the Database Navigator. For more information on selecting objects from the Database Navigator, see Selecting Objects from the Database Navigator on page 150 of the guide, Learning ADAMS/View Basics.



5 Select OK.



Activating and Deactivating ObjectsObjects in ADAMS/View have two states during a simulation: active and inactive. When an object is active, the analysis engine, ADAMS/Solver, includes the object in any simulations that you run. If an object is inactive, ADAMS/Solver ignores the object. For example, if you constrain two parts using a fixed joint to temporarily keep them fixed, you can deactivate the fixed joint during the simulation. The two parts are then free to move relative to each other.

You may find activating and deactivating objects helpful in the following circumstances:

■ You have imported part graphics from a CAD program and you haven’ t constrained all of the parts yet. By deactivating some of them, you can keep them in your modeling database without having them affect the simulation. You can also test each constraint that you create individually.

■ You are debugging your model and you want to see which objects are causing problems. You can deactivate those you think are most likely to be generating errors.

■ You are studying design variations and you want to alternate between different variations. For example, you could create both a bushing and a joint between two parts in your model. During the first simulation, you could activate the bushing and deactivate the joint. During the second simulation, you could deactivate the bushing and activate the joint. Finally, during a third simulation, you could activate both.

Note: You can also create a scripted simulation to turn on and off the activation states of objects during a simulation. For example, to simulate the launching of a missile, you can fix the missile to the plane with a fixed joint and then deactivate the joint during the simulation to simulate the release of the missile. For more on scripted simulations, see Performing a Scripted Simulation on page 107 of the guide, Simulating Models in ADAMS/View.



You can set the activation status of the following objects. All objects are active by default.

■ Groups (You set the activation status of groups as you create them. For more information, see Grouping and Ungrouping Objects on page 431.)

■ Parts (rigid bodies, point masses, and flexible links)

■ Differential equations

■ Markers

■ Constraints

■ Forces

■ Data elements

■ Output controls

When you activate an object, it only becomes truly active if and when all of its ancestors are active. In addition, if you deactivate an object, you also deactivate all its children. For example, if you have a part (PART_1) with two markers (MARKER_1 and MARKER_2), you can only activate MARKER_1 if PART_1 is also active. Also, if you deactive PART_1, you also deactivate its markers. The following figure shows the possible activation states for PART_1 and its markers.

Figure 103. Activation and Deactivation States for Children

If PART_1 is active, thenyou can deactive its child.

If you deactive PART_1, you also deactive its children.

Part_1 Part_1

If you activate PART_1again, its children returnto their previous

Marker_2

activation states. In thiscase, MARKER_1 remains inactive.

Part_1

Marker_1 Marker_2Marker_1 Marker_2Marker_1



To activate or deactivate a selected object:

1 Select the object to be activated or deactivated as explained in Selecting and Deselecting Objects on page 392.

2 From the Edit menu, select either Activate or Deactivate.

If you deactivated an object, ADAMS/View changes its color to indicate it is not active.

To change the activation status of an object on the screen and its children:

1 Right-click the object you want to activate or deactivate.


2 From the pop-up menu that appears, select (De)activate.

The Deactivate/Activate Object dialog box appears.

3 Set the activation of the object and select whether or not you want the object’ s children to inherit the activation status of the parent.

4 Select OK.



To activate or deactivate an object using the Database Navigator:


2 From the Edit menu, select Activate or Deactivate.


3 Select the object you want to activate or deactivate from the Database Navigator. For more on selecting objects from the Database Navigator, see Navigating Through a Modeling Database on page 147 of the guide, Learning ADAMS/View Basics.

4 Select OK.

To determine the activation status of an object:

■ Display information about the object as explained in Viewing Modeling Information on page 171. Be sure that Verbose is selected in the information window so that the window displays all information about the object.



Grouping and Ungrouping ObjectsIf several objects make up a unit or subsystem of your model, you can group them so that you can work on them as a single object. For example, you could group all the objects that make up a suspension system or a handle of a latch. Once you’ve grouped the objects, you can add them to the select list all at once so that you can perform editing operations on them, such as move or copy them. You can also set up their activation and deactivation status during simulations. (For more on the activation and deactivation status of objects, see Activating and Deactivating Objects on page 427.)

When you create a group, you can specify the objects to be included or set up a filter to specify the objects in the group. You can also enter an expression that sets whether or not the objects are active or deactive during a simulation.

To create a group of objects:

1 From the Build menu, select Group.

The Group Create dialog box appears.

Note: The option menu Expand Groups is only present to provide backward compatibility. We recommend that you not use it.

2 Enter a name for the group of objects. ADAMS/View assigns a default name for you.

3 Add any comments about the group that you want to enter to help you manage and identify the group. You can enter any alphanumeric characters. The comments that you create appear in the information window when you select to display information about the group, in the ADAMS/View log file, and in a command or dataset file when you export your model to these types of files.

Do not use



4 Specify the objects to be included in the group as explained in Table 48.

5 Specify whether or not the group of objects is active during a simulation. You can enter an expression that evaluates to 0 (not active) or 1 (active) or enter 1 or 0. If you do not specify a value, ADAMS/View uses the activation status you set using the Activate and Deactivate commands as explained in Activating and Deactivating Objects on page 427.

6 Select OK.

To ungroup objects:

1 From the Build menu, select Ungroup.

The Group Delete dialog box appears.

2 Enter the name of the group of objects you want to ungroup.

To browse for a group in the Database Navigator, right-click the Group Name text box, and select Browse.

3 Select OK.

Table 48. Group Options


Explicitly specify the objects to be grouped

In the Objects in Group text box, enter the names of the objects. Separate each name with a comma (,). To select an object on the screen or browse for an object in the Database Navigator, right-click the Objects in Group text box, and then select the appropriate command.

If you select objects to group using the pop-up menu, ADAMS/View enters commas between the objects.

Set filters for specifying objects to be grouped

In the Objects in Group text box, enter a wildcard and then specify the type of objects in the Type Filter text box. For example, enter Parts to include only rigid bodies or Markers to include only coordinate system markers.



Setting Object AppearanceYou can set how individual objects or types of objects appear in ADAMS/View. You can set the following for any modeling object in your modeling database.

■ Visibility of the object and its name on the screen and how transparent or opaque the object is.

■ Color of the different elements of the object. For example, you can set the color of the object’ s outline or its name.

■ Size of the screen icons that represent the object in your model.

■ Level of detail in an object’s geometry to help improve animation speeds up to factor of 2 for very complex geometry. You will find this particularly helpful when you are using geometry from a CAD system (IDEAS, CATIA, Pro/Engineer, and so on). You can set the level of detail from the original geometry representation (100%) to a minimal representation (1). For example, the following figure shows the impact of reducing a geometry’s level of detail to 10%.

Figure 104. Geometry with Level of Detail Set to 10%

When you first set the level of detail, ADAMS/View must process the geometry. It stores a file for the object in a subdirectory called lod. Once ADAMS/View has processed an object, you can change the object’s level of detail, increasing or decreasing it, without incurring the processing time again.

Note: The lod subdirectory is not portable across platforms.

ADAMS/View supports level of complexity for polygons but the processing tessellates the polygons into triangles.

Original geometry Geometry with level of detail set to 10%



To set the appearance of an object:

1 If desired, select the object whose appearance you want to set as explained in Selecting and Deselecting Objects on page 392. If you do not select an object, you can use the Database Navigator to search for the object.

Shortcut: Right-click the object on the screen, point to the name of the object, and then select Appearance.

2 From the Edit menu, select Appearance.

If you did not select an object, the Database Navigator appears.

3 Select the desired object from the Database Navigator as explained in Navigating Through a Modeling Database on page 147 of the guide, Learning ADAMS/View Basics.

The Edit Appearance dialog box appears.

4 Change the object whose appearance you want to set or specify an entire type of object whose appearance you want to set as explained in Table 49.

Table 49. Object Appearance Options


Explicitly specify the object whose appearance you want to set

In the Entity Name text box, enter the name of the object. To select an object on the screen or browse for an object in the Database Navigator, right-click the Objects in Group text box, and then select the appropriate command. Once the name of the object is in the text box, press Enter to update the dialog box.

Set filters for specifying type of objects whose appearance you want to set

In the Entity Name text box, enter a wildcard and then specify the type of objects in the Entity Type Filter text box. For example, enter Parts to set the appearance of all rigid bodies or Markers to set the appearance of all coordinate system markers.



5 In the Icon Size text box, enter the size you want for the icons. Note that these changes take precedence over the size you specify globally for the modeling database as explained in Setting Screen Icon Display on page 134 of the guide, Learning ADAMS/View Basics.

6 From the Visibility option menu, select how you want to set the visibility of the selected object or object. You can select:

■ On - Turns on the display of the objects.

■ Off - Turns off the display of the objects.

■ Inherit - Lets the objects simply inherit the display settings from its parent. For example, a coordinate system marker inherits settings from its parent part.

7 From the Name Visibility option menu, select whether or not you want the name of the objects displayed in the view window. Refer to Step 6 for an explanation of the choices.

8 From the Color Scope option menu, enter the color you want used for the objects and set which elements of the objects should be affected by the selected color. You can select the following from the Color Scope menu:

■ Polygon Fill sets the color of those areas of a graphic that can be shaded (they include sides of a cylinders, frustums, boxes, and so on).

■ Edge sets the color of the lines making up the edges of the facets of a graphic that can be shaded.

■ Outline sets the color of the lines that make up those graphics that cannot be shaded or filled like the coil of a spring damper.

■ All sets the selected color for all elements of an object.

To browse for a color in the Database Navigator or create a new color, right-click the Color text box, and select Browse or Create.



9 Use the Transparency slider to set how transparent the object or objects are. The higher the value, the more transparent the object is, allowing other objects to show through. The lower the value, the more opaque the object is, covering other objects.

Tip: Setting the transparency of objects can have a negative impact on graphical performance if you are using a graphics card without hardware acceleration for OpenGL. Instead of setting an object’s transparency, consider setting the object’s render mode to wireframe.

10 Use the Level of Detail slider to reduce the complexity of an object’ s graphics to improve animation speed.

11 Select OK.

Setting Object ColorsBy default, ADAMS/View displays each of the objects you create in a different color using its palette of object colors. You can also change the color of any object. In addition, you can modify any of the colors in the palette or create a color of your own. The next sections explain how to work with object colors.

■ Changing an Object’s Color, 437

■ Modifying and Creating Object Colors, 438



Changing an Object’s Color

The Object Color tool stack on the Main toolbox contains 15 colors to which you can set the color of a object. The Object Color tool stack is shown in Figure 105.

Figure 105. Object Color Tool Stack

To change an object’s color:

1 Select the object or objects whose color you want to change as explained in Selecting and Deselecting Objects on page 392.

2 Select a color from the Object Color tool stack.

ObjectColors



Modifying and Creating Object Colors

You can change the colors that are available for displaying objects and create new colors. Note that the color changes are not reflected in the color tools on the Object Color tool stack. These are fixed and remain the same colors as the default colors. To set an object to new colors that you create, use the Object Appearance dialog box as explained in Setting Object Appearance on page 433.

To modify or create a color:

1 From the Settings menu in either the main or plotting window, select Colors. The Edit Color dialog box appears.

2 Do one of the following:

■ To modify a color, select the color that you want to modify from the Color option menu. The selected color appears in the Old color box. Its color values also appear in the Red, Green, and Blue color value sliders. ADAMS/View creates the color by mixing the red, green, and blue light as specified in the color value sliders.

■ To create a new color, select New Color. The New Color dialog box appears. Enter the name of the color and select OK.

3 Change the color values for the color in the Red, Green, and Blue color value sliders, as appropriate.

4 Select OK.

Displays Displays

new colorcurrent color

Set color values

12 Positioning and Rotating Objects

OverviewADAMS/View gives you many ways in which you can move and rotate objects in your model. You can simply select and drag the object to a new location or you can enter precise coordinate locations. You can also use a variety of graphical approaches to rotate and translate objects.

Note that if you move a part, its associated points, center of mass icon, and geometry move along with it. If you move a point, all parts attached to the point move accordingly.

The following sections explain how to position and rotate objects.

■ About the Move Tools, 440

■ Translating Objects Approximately by Dragging, 442

■ Translating and Rotating Objects Using Position Handle, 443

■ Translating and Rotating Objects By Increments, 448

■ Translating and Rotating Objects to an Exact Position, 451

■ Translating and Rotating Objects Graphically, 454

■ Using the Precision Move Dialog Box, 460


Positioning and Rotating Objects440

About the Move ToolsADAMS/View provides three different tools for moving objects:

■ Select tool that lets you select and drag an object.

■ Object position handle.

■ Move tools available from the Move tool stack on the Main toolbox.

The Select tool and Move tool stack are shown next. The object position handle is explained in Translating and Rotating Objects Using Position Handle on page 443.

Figure 106. Move Tool Stack

Move tool stackon Main toolbox

Selecttool



Four of the tools on the Move tool stack are not explained in this chapter because they are shortcuts to other operations or apply more to parameterization. Table 50 lists the tools that are not explained in this chapter and tells you where to find information about them.

As you move objects using the move tools, ADAMS/View provides settings that you can control. It provides the settings in a container at the bottom of the Main toolbox. The settings change depending on the move operation. For example, Figure 106 on page 440 shows the values associated with incrementally moving objects. For more on controlling settings, see Controlling Settings on page 54 of the guide, Learning ADAMS/View Basics.

To display the contents of the Move tool stack:

■ From the Main toolbox, right-click the Move tool stack. By default, the

Increment tool appears at the top of the tool stack.

Table 50. Move Tools Explained in Other Chapters

The tool: Is explained in the section or chapter:

Coordinate System tool Specifying the Type of Coordinate System on page 30 of the guide, Learning ADAMS/View Basics.

Working Grid tool Setting Up the Working Grid on page 127 of the guide, Learning ADAMS/View Basics.

Parameterization tools f(x) and f(θ)

Using the Parameterization Move Tools on page 18 of the guide, Refining Model Designs in ADAMS/View.



Translating Objects Approximately by DraggingYou can quickly translate objects by dragging them. To protect you from accidentally translating objects, you need to press Ctrl and Shift before you can translate the objects. You can translate objects in the working grid if it is turned on or about the global coordinate system.

To translate objects by selecting and dragging:

1 Select the objects that you want to translate as explained in Selecting and Deselecting Objects on page 392.

2 Hold down the Ctrl and Shift keys.

3 Click anywhere on the selected objects and hold down the mouse button.

4 Drag the selected objects to the desired location and release the mouse button.



Translating and Rotating Objects Using Position HandleThe object position handle is a powerful tool for translating and rotating various objects in your model. It translates an object along its axes and rotates the object about its axes. If the working grid is displayed, both the translation and the rotation are incremented using the set grid spacing. The object position handle is shown below.

Figure 107. Object Position Handle

The following sections explain how to use the position handle in more detail.

■ Displaying the Object Position Handle, 444

■ Translating an Object Along Its Axes, 445

■ Rotating an Object About Its Axes, 446

■ Rotating an Object By Increments About View Origin, 448

■ Translating an Object By Increments Along View Axes, 450

■ Creating a Global Position Handle, 447

X axisZ axis

Y axis

Ball

Stem



Displaying the Object Position Handle

The object position handle appears when you first create a modeling object, such as a link or force. You can also display the position handle at any time. The object position handle is shown in Figure 107.

To display the position handle on an object:

■ Select the object on which you want to display the handle. To see the handle, you can have only one object selected. See Selecting and Deselecting Objects on page 392 for more information.

The position handle appears. It appears over the first point of the geometry that you created or in the center of spherical geometry. The following shows the position handle as it appears on a box, sphere, and translational joint.

Figure 108. Examples of the Object Position Handle

cm



Translating an Object Along Its Axes

You can use the object position handle to translate an object along an axis of the object position handle.

To translate an object along its axes:

1 Display the position handle as explained in Displaying the Object Position Handle on page 444.

2 Click on any of the axis stems of the object position handle and drag the stem. The position handle moves the object in either direction along the selected axis.

Figure 109. Example of Translating an Object about Its Axis

Dragging the X axis stem... Moves the link parallel to its X axis

y

z

x

y

z

x

y

z

x

y

z xy

z x

y

z

x

y

z

x

y

z

xy

z xy

z x



Rotating an Object About Its Axes

You can use the object position handle to rotate an object about an axis of the object position handle.

To rotate the object about any of its three axes:

1 Display the position handle as explained in Displaying the Object Position Handle on page 444.

2 Click on the ball at the end of any of the axes of the handle and pivot the axis around the origin of the handle. Moving the x-axis ball rotates about the y-axis, moving the y-axis ball rotates about the z-axis, moving the z-axis ball rotates about the x-axis.

Note: You can also use the object position handle to rotate an object in the plane of the screen when one axis of the object is perpendicular to the screen.

Figure 110. Example of Rotating an Object About its Z-Axis

Tip: To gain more precise control on the rotation angles, move the mouse away from the center of the position handle as you rotate the object. The farther you move the mouse away from the position handle, the smaller ADAMS/View makes the angles of rotation.

Pivoting the Z axis... Rotates the link



Creating a Global Position Handle

You can create a global position handle with respect to the which you can translate and rotate selected objects. When you create a global position handle, ADAMS/View turns off the object position handle for individual objects.

Note: You can also locate the global position handle by entering precise locations as explained in Translating and Rotating Objects to an Exact Position on page 451. If other objects are also selected, ADAMS/View moves them to positions relative to the new position of the global position handle.

To set a global position handle:

1 Do either of the following:

■ From the Settings menu, select Object Position Handle.

■ From the Move tool stack, select Object Position Handle tool .

The Object Handle Settings dialog box appears.

2 Select Set Handle Location and click on the screen to indicate the location for the handle.

3 If desired, orient the axes of the handle as explained below. By default, the orientation of the position handle is set to that of the current working grid axes.

■ Select how you want to orient the handle from the Orientation Via option menu.

■ Select Orientation Via and define axes as necessary.

4 Select Close.

To turn off the global position handle:

■ Select Reset from the Object Handle Settings dialog box.

Note: You can also delete the global position handle just as you would any object in your modeling database as explained in Deleting Objects on page 413 of the guide, Learning ADAMS/View Basics.



Translating and Rotating Objects By IncrementsYou can position an object incrementally by specifying the angle of rotation or the translational distance. The next two sections explain how to translate and rotate objects by increments:

■ Rotating an Object By Increments About View Origin, 448

■ Translating an Object By Increments Along View Axes, 450

Rotating an Object By Increments About View Origin

You can select to rotate an object by increments about the center (origin) of the view window. As you rotate the object, you can select where the origin of the view window is.

Figure 111. Example of Rotating Object by Increments

Note: For another way in which to center the view, see Setting the Center of a View on page 106 of the guide, Learning ADAMS/View Basics.

Setting center of mass of box to viewcenter and incrementally rotating...

Rotates box about its centerof mass in the view plane



To incrementally rotate an object:

1 Select the object that you want to move as explained in Selecting and Deselecting Objects on page 392.

2 From the Move tool stack, select the By Increments tool .

The settings in the container on the Main toolbox change to those for incrementally positioning objects, as shown below.

Note: For information on setting the view orientation using the shortcuts, see Orienting a View Precisely on page 102 of the guide, Learning ADAMS/View Basics.

3 If desired, select a new view center about which to rotate the object. To select a new center:

■ Select the blank box in the center of rotation arrows.

■ Select a point on screen about which you want to rotate the object.

Rotates about the

Rotates about the

Rotates about z-axis of view

y-axis of viewSpecifies

x-axis of view

increment

Sets pivot

Shortcuts to settingview orientation

point



4 In the Angle text box, set the amount by which you want to incrementally rotate the object.

5 Select the appropriate rotation arrows to rotate the object. ADAMS/View rotates the object each time you select an arrow.

Translating an Object By Increments Along View Axes

To incrementally translate object along view coordinate system axes:

1 From the Move tool stack, select the By Increments tool .

The settings in the container on Main toolbox change to those for incrementally positioning objects, as shown below.

Note: For information on setting the view orientation using the shortcuts, see Orienting a View Precisely on page 102 of the guide, Learning ADAMS/View Basics.

2 In the Distance text box, set the amount by which you want to incrementally translate the object.

3 Select the appropriate translation arrows to translate the object along the x- or y- axis of the view coordinate system. ADAMS/View translates the object each time you select an arrow.

Translates along

Translates alongthe y-axis

Specifies increment

the x-axis

Shortcuts to settingview orientation



Translating and Rotating Objects to an Exact PositionYou can position an object precisely by specifying the translational coordinates and the rotational angles of the object’ s position handle relative to the working grid axes, global coordinate system, or any object on the screen. In addition, you can display the current position of an object’s position handle.

The following figure shows an example of entering the exact location of a box’ s object handle position so that the handle is in the same position as the handle of a second box.

Figure 112. Example of Setting Exact Position of an Object

If more than one object is selected or you’ve created a global position handle, ADAMS/View moves the first object you selected or the handle to the specified location and moves all other selected objects to positions relative to the first selected object or the handle. For information on creating a global position handle, see Creating a Global Position Handle on page 447.

To position an object precisely or get the location of an object:

1 Select the object or objects that you want to position or the object whose coordinate location you want to display as explained in Selecting and Deselecting Objects on page 392.

2 From the Move tool stack, select the Exact Position tool .

The settings in the container on the Main toolbox change to those for precisely positioning objects, as shown in Figure 113 on page 452.

Moves the lower box to the locationand orientation of the upper box

Setting the lower box position tothe position of the upper box...



Figure 113. Move Tool Stack for Exact Position

3 Do one or more of the following:

■ Select Get to obtain the coordinates of the selected object.

■ In the 1, 2, or 3 Location and Orientation text boxes, enter the locations and orientations to which you want to move the object.

The coordinate locations are in the current coordinate system. For example, if the coordinate system is set to Cartesian, then Location 1 is the x coordinate.

Orientation 1 is the first rotation angle, Orientation 2 is the second, and Orientation 3 is the third. The axis to which ADAMS/View applies these angles depend on the current rotation sequence. For example, if the rotation sequence is body-fixed 313, ADAMS/View applies Orientation 1 to the z-axis. For more on rotation sequences, see the section, About Orientation Angles and Rotations on page 34 of the guide, Learning ADAMS/View Basics.

Exact Position containeron Main toolbox



4 Select the object to which the locations and orientations are relative. The coordinates are relative to the location of the object’ s position handle. By default, the coordinates are relative to the working grid.

If you selected that the coordinates are relative to an object, enter the object in the lower text box. To browse for an object or select an object from a list, right-click the lower text box, and then select the appropriate command.

5 Select Set.



Translating and Rotating Objects GraphicallyThe move tools provide you with several ways to graphically move objects. For example, you can translate objects from one selected location to another or select faces of objects to mirror or align. The next sections explain how to graphically move objects:

■ Translating From Initial Location to Another, 454

■ Rotating Objects About or Aligning with Grid or Features, 456

■ Positioning Object By Aligning Faces, 459

Translating From Initial Location to Another

You can quickly and accurately move objects by translating them from an initial location to another. There are two ways to move an object from one location to another:

■ Pick two locations. The first location defines the location from which to move and the second location defines the point to which to move the selected object. The objects move relative to the selected locations.

■ Define a distance and a vector along which to translate the selected objects.

The following figures shows a link (LINK_2) being centered over a hole of LINK_1 by moving the link from position A to position B.

Figure 114. Example of Translating From One Location to Another

As you translate the objects you can rotate an object that you select during the translation operation or translate all objects currently selected. In addition, you can translate a copy of the selected objects instead of the actual objects.

Centers the two link holes

B

Translating a link from A to B...



To translate objects from one location to a another by defining two points:

1 From the Move tool stack, select the Point-to-Point tool .


■ If desired, select Selected to translate the currently selected objects.

■ If desired, select Copy to translate a copy of the selected object or objects.

■ Select From To from the option menu.

3 If you did not choose Selected in the settings container, select the object that you want to translate.

4 Select the first point on the screen from which to translate the object or objects.

5 Select the second point on the screen to which to translate the object.

To translate objects along a vector:

1 From the Move tool stack, select the Point-to-Point tool .


■ If desired, select Selected to translate the currently selected objects.

■ If desired, select Copy to translate a copy of the selected object or objects.

■ Select Direction Distance from the option menu and enter the distance to translate the object in the Distance text box.

3 Select the object that you want to translate if you did not select Selected in the settings container.

4 Select an axis or define the vector along which to translate the object by selecting two points on the screen.



Rotating Objects About or Aligning with Grid or Features

You can quickly and accurately rotate objects about an axis or align them with the axes of other objects. You can set the alignment in the following ways:

■ About - Rotates an object about the axis of another object.

■ Align - Rotates an object about its axis to align it with another object.

■ Align Same As - Aligns an object to the orientation of another object.

■ Align One Axis - Orients an axis of an object to be in the same direction as the axis of another object. This is useful if the axis of a joint or force is defined by a marker in your model.

■ Align Two Axis - Orients an object so it is the same direction as the axis of another object and rotates the object about that axis to place a second axis in the plane defined by the two directions.

You can rotate an object that you select during the rotate operation or rotate all objects currently selected. In addition, you can rotate a copy of the selected objects instead of the actual objects.

Figure 115. Example of Aligning Axes of Two Objects

Aligning the z axis of linkto the z axis of the cylinder...

Rotates the link about its axisso it aligns with the cylinder.



To rotate objects about an axis or axes:

1 From the Move toolstack, select the Align & Rotate tool .


■ To rotate the currently selected objects, select Selected.

■ To rotate a copy of the selected object or object, select Copy.

■ From the option menu, select the method you want to use to rotate or align objects. If you selected About, enter the amount to rotate the object in the Angle box.

3 If you did not choose Selected in the settings container, select the object or objects that you want to rotate.

4 Follow the prompts in the status bar to select the axis or axes about which to rotate or align the objects. Refer to Table 51 for assistance.

Table 51. Options for Rotating Objects


About ■ Select the axis about which to rotate the object or objects.

Align 1 Select the axis about which to rotate the object or objects.

2 Select the axis to move.

3 Select the axis with which to align the object.

Align Same As ■ Select the object to which you want to align the already selected objects.

Align One Axis 1 Select the axis of the object to align.

2 Select the object to which to align the axis.



Align Two Axis 1 Select the first axis of the object to control (x, y, or z).

2 Select the object to which to direct the first axis.

3 Select the second axis of the object to control.

4 Select the object towards which to direct the second object.

Note: ADAMS/View rotates the object so that the first axis points toward the first object, and the second axis points as closely as possible towards the second object.

Depending on the locations that you selected, it may not be possible for both axes to pass through the locations. ADAMS/View orients the object so that the first axis passes through the first location, and the plane defined by the two axes passes through the second location. This means that the second axis comes as close as possible to the second location, but may not pass through it.

Table 51. Options for Rotating Objects (continued)




Positioning Object By Aligning Faces

You can quickly position an object by mating one object face with another object face so they are in the same plane. The following figure shows two objects whose top and bottom faces were mated.

Note: The objects must be in shaded render mode to mate their faces. For more information, see Setting View Rendering on page 118 of the guide, Learning ADAMS/View Basics.

Figure 116. Example of Aligning Faces

To align an object’s face with another object’s face:

1 From the Move tool stack, select the Mate Faces tool .

2 Select the face of the object to be aligned.

3 Select the face with which to align the selected object’ s face.

Mating faces of geometry... Aligns the faces to the same plane

Faces to be mated



Using the Precision Move Dialog BoxADAMS/View provides a Precision Move dialog box to help you move objects:

■ By increments

■ To precise coordinates

You can select to move the objects relative to a specified object’s coordinate system, called the reference coordinate system. You can also select to move objects relative to the screen. In addition, you can use the Precision Move dialog box to view the coordinates of one object in relation to another. Figure 117 shows the Precision Move dialog box as it appears when you move objects relative to a model.

Figure 117. Precision Move Dialog Box

The Precision Move dialog box consolidates some operations that are available using the By Increments and Precise Coordinates tools and provides new functionality for rotating objects by increments relative to any object. (For more information on the other tools, see Translating and Rotating Objects By Increments on page 448 and Translating and Rotating Objects to an Exact Position on page 451.)

Rotate and translate objects by increments relative to the or about the Part to be

Coordinates to which object

relative to the or about the

Loads current coordinatesinto the C1 - C3 and A1 - A3 boxesmoved

should be moved

object’s coordinate system

object’s coordinate system



The next sections provide information on using the Precision Move dialog box:

■ Overall Procedure for Using the Precision Move Dialog Box, 461

■ Accessing the Precision Move Dialog Box, 462

■ Selecting the Objects to Move, 462

■ Selecting the Reference Coordinate System, 462

■ Moving Objects Relative to or About Coordinate System by Increments, 464

■ Viewing Locations of Objects Relative to Other Objects, 467

■ Moving Objects Relative to or About Coordinate System by Precise Coordinates, 468

■ Translating and Rotating Objects Using Screen Coordinates, 469

Overall Procedure for Using the Precision Move Dialog Box

The following provides general instructions for moving objects using the Precision Move dialog box. The next sections explain each of the steps in more detail.

To move objects using the Precision Move dialog box:

1 Select the objects to be moved.

2 If you want to move the objects along or about axes that another object in the model defines (the reference coordinate system), then select either Relative to the or About the, and enter the name of the object that is to define the reference coordinate system.

Note: If you do not enter a reference coordinate system, ADAMS/View moves the objects about the default coordinate system.

3 Then, either:

■ If you know the destination coordinates of the objects you are moving, enter the destination coordinates into the C1 through C3 (for translation) and A1 through A3 (for rotation) text boxes, and then select OK.

■ Use the Rotate and Translate dials to move the objects by incremental values.



Accessing the Precision Move Dialog Box

To display the Precision Move dialog box:

■ From the Move tool stack, select the Precision Move tool .

Selecting the Objects to Move

When you display the Precision Move dialog box, ADAMS/View places all selected objects in it so you can quickly move them. You can also change the objects to be moved.

To select an object to move:

1 Set Relocate the to the desired object type (for example, part or marker).

2 Enter the name or names of the objects to move. You can select the object on the screen, enter the name of the object, or browse for the object.

Selecting the Reference Coordinate System

By default, the Precision Move dialog box moves the selected objects relative to the default coordinate system. You can specify that ADAMS/View use a different coordinate system as the reference coordinate system. The rotational and translational coordinates you enter for the move or the incremental values you select are with respect to the origin and orientation of this coordinate system. You can select the following types of objects:

■ Model - Global coordinate system.

■ Part or marker - Part or marker in your model.

■ View - ADAMS/View defined view, such as front, right, or left. Use the Database Navigator to select the name of the view.

■ Entity - Any entity, including those that are not on the screen. Entities also include the working grid and gravity.

■ Screen - The plane of the screen. When you select to move objects relative to the screen, the Precision Move dialog box changes. For more information, see Translating and Rotating Objects Using Screen Coordinates on page 469.



You can specify two options for the reference coordinate system: Relative to the or About the:

■ If you specify the Relative to the option for rotations, objects rotate in place (their locations do not change) and their rotations are with respect to the coordinate system specified in the Relative to the text box.

■ If you specify the About the option for rotations, the objects rotate about the origin of the coordinate system specified (their locations change) and the rotations are with respect to the coordinate system specified in the About the text box.

■ Translations are with respect to the coordinate system defined as either Relative to the or the About the.

To set the reference coordinate system:

1 Set the second option to either Relative to the or About the.

2 In the text box to the right, enter the object whose coordinate system is to be used as the reference coordinate system.

Note: If you do not enter a reference coordinate system, the Precision Move dialog box moves the objects about the current default coordinate system.



Moving Objects Relative to or About Coordinate System by Increments

The Rotate and Translate dials on the left side of the Precision Move dialog box (Figure 117 on page 460) move an object with respect to a body-fixed or reference coordinate system in incremental amounts. You specify the reference coordinate system using the Relative to the and About the options (see Selecting the Reference Coordinate System on page 462).

Figure 118. Reference Coordinate System Options in Precision Move Dialog Box

To change the incremental value:

■ Enter new values for translation or rotation in the text boxes below the cubes, and then press Enter.

To change the direction of the move:

■ Click the + or -.

To move an object relative to or about another object:

1 Select the object to move.

2 Set the reference coordinate system.

3 Click a cube for the direction you want to translate or rotate the object.

Change direction

Clicking a cubemoves the object

Incremental value

of move

in the specified direction



Example One:

Rotate a marker (MAR2) 180 degrees relative to the y axis of the coordinate system that MAR1 defines:

1 Set Relocate the to marker, and then enter MAR2 in the text box to the right.

2 Set Relative to the, and then enter MAR1 in the text box to the right.

3 Set the increment value to 180.

4 Click the y cube on the Rotate dial.

Figure 119. Rotating Marker Relative to Another Marker

MAR2

MAR1

Rotating MAR2 180 degreesrelative to the y-axis of MAR2 ...

Results in the followingposition for MAR2.

MAR2

MAR1



Example Two:

Rotate a marker (MAR2) 45 degrees about the y axis of MAR1:


2 Set About the, and then enter MAR1 in the text box to the right.

3 Set the increment value to 45.

4 Click the y cube on the Rotate dial.

Figure 120. Rotating Marker About Another Marker

MAR2

MAR1

Rotating MAR2 45 degreesabout y-axis of the MAR1 ...


MAR2

MAR1



Viewing Locations of Objects Relative to Other Objects

You can use the Precision Move dialog box to view the current coordinates of an object with respect to the coordinate system of another object (reference coordinate system).

ADAMS/View displays the coordinates in the six position text boxes (C1 through C3 for translation and A1 through A3 for rotation) of the Precision Move dialog box (see Figure 117 on page 460).

For example, if you want to ensure that two markers, which you want to connect using an inplane joint, are in the same plane, you can set one marker as the object to be moved and the other object as the relative to object. You can then view the rotation coordinates of the first marker to ensure that they are (0, 0, 0).

To view current coordinates:



3 Select Load.

ADAMS/View loads the current coordinates relative to the reference coordinate system.



Moving Objects Relative to or About Coordinate System by Precise Coordinates

Using the Precision Move dialog box, you can move an object to precise coordinates relative to another object’s coordinate system (the reference coordinate system). You specify the reference coordinate system using the Relative to the and About the options (see Selecting the Reference Coordinate System on page 462). You enter the coordinates in the six position text boxes (C1 through C3 for translation and A1 through A3 for rotation) of the Precision Move dialog box (see Figure 117 on page 460).

To move an object to coordinates relative to a reference frame:



3 Change the values in the C1 through C3 and A1 through A3 text boxes.

4 Select OK.

Example:

Move a marker (MAR2) to (0, -4, -4) in another marker’s (MAR1) coordinate system.


2 Set Relative to the, and then enter MAR1 in the text box to the right.

3 In the C1 through C3 text boxes, enter:

■ C1: 0

■ C2: -40

■ C3: -40

4 Select OK.

Figure 121. Moving Marker Relative to Another Marker by Precise Coordinates

MAR2

MAR1

Moving MAR2 to the coordinates (0, -40, -40) ...


MAR2

MAR1



Translating and Rotating Objects Using Screen Coordinates

You move an object based on screen-fixed coordinates. The active view defines the screen-fixed coordinate system. Regardless of the object’s orientation in the active view, the move is relative to the screen coordinates.

When you select to move an object based on screen coordinates, the Precision Move dialog box changes the dials on the left to those shown in Figure 122. The dials translate and rotate the objects:

■ Think of the translation as pulling the object in the direction of the arrow. For example, when you select the small arrow that points up, you pull an object up along the vertical axis. The double arrows to the right translate an object along an axis that is normal to the screen (works only if the view is in perspective mode).

■ Think of the rotation as pushing on an object at that point. For example, if you select the arrow that points to the right, you are pushing the horizontal axis back, resulting in a positive rotation around the vertical axis.

Figure 122. Screen Options in Precision Move Dialog Box

Specifies increment

Clicking an arrowmoves objects in

Translates intoand out of axis

Rotates objects

normal to screenarrow direction

normal to screen



To move an object in screen coordinates:



3 Click an arrow for the direction you want to translate or rotate the object.

A - B

U - V

W - Z

C - D

E - F

G - H

I - J

K - L

S - T

Q - R

O - P

M - N


Index471

Index

A - BAccessing modify dialog boxes 420

Activate command, using 429

Activatingdetermining status of 430objects 427

ADAMS/View standard material types 118

ADAMSMAT format 360

Addingrows 104rows to Spline Editor 346

Aggregate mass, calculating 120

Aggregate Mass, using 120

Align & Rotate toolusing to align objects 457using to rotate objects 457

Aligning faces 459

Alphanumeric sorting 410

Animations, setting level of detail for 433

Appearance command, using 434

Appearance, setting object 433

Append row to X & Y data button, using 346

Append Z Value button, using 346

Applied forcesSee also Multi-component forcesSee also Single-component forcesdescribed 196, 203

A - B

U - V

W - Z

C - D

E - F

G - H

I - J

K - L

S - T

Q - R

O - P

M - N


Index472

Applying changes in Table Editor 418

Arcscreating 25modifying 88

Array command, using 320

Arrayscreating 320creating contact 308determining size of 319modifying 320modifying contact 310overview of 317types of 318using with system elements 369

Beamsconstitutive equations for 246creating 248described 244modifying 249

Bodies/Geometry command, using 15

Boolean operationdifference 55intersection 54union 53

Boss tool, using 59

Bossesadding to objects 59modifying 101

Box tool, using 33

Boxescreating 32modifying 92

A - B

U - V

W - Z

C - D

E - F

G - H

I - J

K - L

S - T

Q - R

O - P

M - N


Index473

Bushing tool, using 229

Bushingsabout 226constitutive equations for 227creating 229modifying 231

By Increments toolusing to rotate objects 449using to translate objects 450

C - DCalculating aggregate mass 120

Camscontact points on 276creating 275initial conditions for 278modifying 278tips on creating 276types of 272

Cautionsfor field elements 264for general state equations 382for linear state equations 378for state variables 372

Cellsediting text in 344entering object names into 416entering text in 344, 415inserting text into multiple 103, 415modifying current contents 417moving between 344viewing contents of 345

Chain tool, using 49

Chaining, wire geometry 49

Chamfer tool, using 58

A - B

U - V

W - Z

C - D

E - F

G - H

I - J

K - L

S - T

Q - R

O - P

M - N


Index474

Chamferingcreating 57modifying 101

Changes, applying in Table Editor 418

Circlescreating 25modifying 88

Closed curves, specifying 327

Colorscreating 438modifying 438setting object 437setting object element 433

Colors command, using 438

Columnsmoving between 344resizing 103, 346

Complex geometry, creating 49–56

Complex jointsSee also Coupler jointsSee also Gear jointsdescribed 140working with 163–171

Complexity, setting level of for geometry 433

Conditionssetting initial for motion 183setting initial for simple joint 159

Connectors, See Flexible connectors

Constant-velocity jointcreating 153described 147modifying 155

A - B

U - V

W - Z

C - D

E - F

G - H

I - J

K - L

S - T

Q - R

O - P

M - N


Index475

Constitutive equationsfor beams 246for bushings 227for field elements 256for torsion springs 238

ConstraintsSee also ContactsSee also Idealized jointsSee also Joint primitivesabout 126about connecting to parts 132accessing tools for creating 134how oriented 133naming 133tips on creating 136types of 127

Construction geometrychaining 49creating 18–30described 13extruding 50modifying using dialog boxes 81–101modifying using hotpoints 80

Contact arraysabout 308creating 308modifying 310

Contact Force tool, using 293

Contact forcesalgorithms used in 290creating 293example of 297more about 311supported geometry in 291with planar geometry 291

A - B

U - V

W - Z

C - D

E - F

G - H

I - J

K - L

S - T

Q - R

O - P

M - N


Index476

Contact pointabout 276specifying initial for curve-on-curve cam 279specifying initial for pin-in-slot cam 278

Contactsdegrees of freedom removed 130described 196See CamsSee Contact forcesSee Force-based contact

Control pointsdefined 322using to define curves 325

Conventionsconstraint naming 133force naming 200part naming 8

Convex curves on cams 276

Coordinate system marker, See Markers

Coordinate systemslocal 7moving objects relative to/about 464, 468

Copy command, using 421

Copy Object command, using 411

Copy tool, using 421

CopyingMFORCE 269objects 421objects in Table Editor 411text in cells 344

Cornerschamfering 57filleting 57

A - B

U - V

W - Z

C - D

E - F

G - H

I - J

K - L

S - T

Q - R

O - P

M - N


Index477

Coupler jointabout 168creating 169modifying 169

Coupler tool, using 169

Create Forces tool stackabout 201using 202

Create Trace Spline command, using 77

Creatingarcs and circles 25arrays 320beams 248boxes 32bushings 229complex joint 163contact arrays 308contact forces 293coupler joint 169curve data element 329cylinders 35differential equations 375extrusion 43field elements 258force-based contacts 305frustums 37gear joint 166general state equations 383global position handle 447joint motion 182joint primitives 172linear state equations 378lines and polylines 23links 40markers 21

A - B

U - V

W - Z

C - D

E - F

G - H

I - J

K - L

S - T

Q - R

O - P

M - N


Index478

matrixes 353–359MFORCE 266multi-component forces 221object colors 438objects in Table Editor 412planes 34plates 41point masses 73point motion 187points 18revolutions 47simple joint 153single-component forces 210spheres 36spline from trace 77splines 28spring-dampers 234state variables 373tips on, parts 9torsion springs 240torus 38transfer functions 389

Crowd, selecting objects in 395

CSG, defined 52

Curve command, using 329

Curve data elementscreating/modifying 329defining with controls points 325defining with curve points 326how used in model 328specifying open or closed 327steps in defining 323ways to define 322

A - B

U - V

W - Z

C - D

E - F

G - H

I - J

K - L

S - T

Q - R

O - P

M - N


Index479

Curve pointsdefined 322using to define curves 326

Curve-fitting techniquesin ADAMS/View 335setting in Spline Editor 343

Curve-on-curve camcreating 275described 274initial conditions for 279modifying 278tips on 276

Curve-on-curve tool, using 275

Curves, creating splines from 30

Cut tool, using 56

Cuttingsolid geometry 55text in cells 344

Cylinder tool, using 35

Cylinderscreating 35modifying 93

Cylindrical jointadding friction to 162creating 153described 144modifying 155setting initial conditions for 159

Damping coefficient, specifying for torsion spring 242

Damping matrixspecifying for beam 253specifying for field element 263

A - B

U - V

W - Z

C - D

E - F

G - H

I - J

K - L

S - T

Q - R

O - P

M - N


Index480

Damping ratio, specifying for beam 253

Data elementsarrays 317–321curves 322–331matrixes 352–363overview of 315splines 332–346strings 364types of 316

Data filesdefining matrix using 359format for matrixes 360

Data points, editing spline 342

(De)activate command, using 429

Deactivate command, using 429

Deactivatingdetermining status of 430objects 427

Definingforce direction 199magnitude of force 198

Degrees of freedomabout 128for parts 8that contacts remove 130that idealized joints remove 129that joint primitives remove 130that motions remove 131

Delete command, using 424

DeletingMFORCE 269objects 423objects using Table Editor 413rows 104

A - B

U - V

W - Z

C - D

E - F

G - H

I - J

K - L

S - T

Q - R

O - P

M - N


Index481

Determiningactivation status of objects 430array sizes 319

Dialog boxesabout part modify 106displaying modify 420using to modify geometry 81

Differential Equation command, using 375

Differential equationscreating/modifying 375overview of 374ways to define 374ways to use 375

Directionoverview of defining force 199specifying for single-component force 208

Discrete Flexible Links command, using 67

Displacements, specifying initial for motions 183

DisplayingLocation table 103modifying dialog boxes 420object position handle 444objects in Table Editor 404Select List Manager 397Spline Editor 337Table Editor 402

Distances, measuring between markers 122

DOF, See Degrees of freedom

Dragging objects 442

Dynamic friction, adding to joints 162

A - B

U - V

W - Z

C - D

E - F

G - H

I - J

K - L

S - T

Q - R

O - P

M - N


Index482

E - FEdges

chamfering 57filleting 57

ElementsSee Data elementsSee System elements

Entering mass moments of inertia for parts 112

Equationsconstitutive for bushings 227constitutive for field elements 256for beams 246for spring-dampers 234for torsion springs 238

Equilibrium, controlling using system elements 369

Exact Position tool, using 451

Examplesof contact forces 297of creating spline from trace 75of system elements 368of using spline 333

Expressions, with arrays 318

Extrude tool, using 51

Extruding geometry 50

Extrusion tool, using 46

Extrusionscreating 43limits of 44modifying 98

Faces, aligning 459

Features, moving objects along 456

A - B

U - V

W - Z

C - D

E - F

G - H

I - J

K - L

S - T

Q - R

O - P

M - N


Index483

Field Element tool, using 258

Field elementsabout specifying linear 255about specifying nonlinear 255cautions for 264constitutive equations for 256creating 258described 255modifying 259

Filesmatrix data 360reading in Location table information 105saving Location table information to 105saving Table Editor information to 419

Fillet tool, using 58

Filletingcreating 57modifying 101

Filtering, information in Table Editor 407

Fixed jointscreating 153described 149modifying 155

Flexible bodiesviewing preloads of 270

Flexible connectorsSee also BeamSee also BushingsSee also Field elementSee also Spring-dampersSee also Torsion springdescribed 196, 226

A - B

U - V

W - Z

C - D

E - F

G - H

I - J

K - L

S - T

Q - R

O - P

M - N


Index484

Flexible linksabout 63creating 67modifying 73positioning 65types of 64

Force graphicsdisplaying for bushing 231displaying for multi-component forces 223displaying for single-component forces 212displaying for spring-dampers 235displaying for torsion springs 241

Force magnitudeabout defining 198about defining for applied forces 204calculating for multi-component forces 218modifying for multi-component forces 223modifying for single-component force 212specifying characteristics for single-component force 211, 222

Force-Based Contact tool, using 305

Force-based contactsabout geometry for 311and simulation results 311contact arrays for 308creating 305friction with 312modifying 307modifying contact array for 310types of pairs 303

A - B

U - V

W - Z

C - D

E - F

G - H

I - J

K - L

S - T

Q - R

O - P

M - N


Index485

ForcesSee also Applied forcesSee also Flexible connectorsSee also Multi-component forcesSee also Single-component forcesaccessing tools for creating 201defining direction of 199defining magnitude of 198described 196naming convention 200specifying direction for single component 208

Forces command, using 202

Formatsfor matrices 352for matrix data files 360

Frictionabout using with force-based contacts 312adding to joints 162specifying for contact forces 309

Frustum tool, using 37

Frustumscreating 37modifying 95

FSAVE format, using with matrices 360

Full formatdefining matrix using 354described 352

Function Builder, See the guide Using the ADAMS/View FunctionBuilder 195

Function expressionsdefining for force 198defining for motion 179using with arrays 318

A - B

U - V

W - Z

C - D

E - F

G - H

I - J

K - L

S - T

Q - R

O - P

M - N


Index486

G - HGear joint

algebraic equation for 165creating 163creating and modifying 166ratio 165

Gear tool, using 166

General force vector, See Six-component general force vector

General point motioncreating 187described 186

General point motion tool, using 188

General State Equation command, using 383

General state equationscautions with 382creating/modifying 383overview of 381ways to use 382

General/initial conditions arrayscreating/modifying 320described 318determining size of 319

Geometric Modeling tool stack, about 14

Geometric Modeling tool stack, using 15

Geometryaccessing 14adding holes and bosses to 59chaining wire 49chamfering 57creating box 32creating cylinders 35creating extrusion 43creating from intersection 54creating from union of two 53

A - B

U - V

W - Z

C - D

E - F

G - H

I - J

K - L

S - T

Q - R

O - P

M - N


Index487

creating frustum 37creating link 40creating plane 34creating plate 41creating revolution 47creating sphere 36creating torus 38cutting one solid from another 55extruding 50filleting 57hollowing 60modifying using dialog boxes 81–101modifying with hotpoints 80setting level of detail of 433splitting solid 56supported in contacts 291types of 13types of spline 76

Global position handlecreating 447turning off 447

Graphically positioning objects 454

Ground partdescribed 7moving objects on it 7

Group command, using 431

Groupscreating for objects 431selecting 400

Hole tool, using 59

Holesadding to objects 59modifying 101

Hollow tool, using 61

A - B

U - V

W - Z

C - D

E - F

G - H

I - J

K - L

S - T

Q - R

O - P

M - N


Index488

Hollowing objectscreating 60modifying 101

Hooke jointadding friction to 162creating 153described 151modifying 155

Hotpointsusing to edit splines 342using to modify geometry 80

I - JIdealized joints

See also Complex jointsSee also Simple jointsabout 140degrees of freedom removed 129described 127

IMPACT-function-based contact, about 290

Increments, positioning objects by 448

Inertiaentering mass moments of for parts 112modifying part 108

Informationmodifying cell 417reading from file 105saving to file 105, 419setting in Table Editor 407

Initial conditionsfor cams 278modifying location and orientation for parts 116setting for simple joint 159setting velocities for parts 113specifying for motions 183

A - B

U - V

W - Z

C - D

E - F

G - H

I - J

K - L

S - T

Q - R

O - P

M - N


Index489

Initial displacements, specifying for motions 183

Initial location, positioning objects from 454

Initial point of contactfor curve-on-curve cams 279for pin-in-slot cams 278

Initial velocitiesmodifying for parts 113specifying for motions 183

Inline joint, creating 172

Inplane joint, creating 172

Input text boxentering text in 415using to insert text into multiple cells 415

Inputs (U) arrayscreating/modifying 320described 318

Insertingrows 104

Inserting text into multiple cells 103, 415

Intersect tool, using 54

Intersecting geometry 54

Joint motioncreating 182described 178modifying 183

Joint primitivescreating 172degrees of freedom removed 130described 127

Joint tool stackabout 134using 135

A - B

U - V

W - Z

C - D

E - F

G - H

I - J

K - L

S - T

Q - R

O - P

M - N


Index490

JointsSee also Idealized joints; Primitive jointsadding friction to 162

Joints command, using 135

K - LLevel of detail, setting for geometry 433

Limits for planar geometry in contacts 291

Linear extrapolation, selecting in Spline Editor 340

Linear forcesabout specifying field element as 255bushing 226defining field element as 259spring-damper 233torsion spring 238

Linear State Equation command, using 378

Linear state equationscautions for 378creating/modifying 378overview of 377

Linescreating 23modifying 87

Link tool, using 40

Linkscreating 40flexible, working with 63–73modifying 97

Local coordinate systems, described 7Location Table

adding rows 104inserting text into multiple cells of 103resetting 105resizing columns 103

A - B

U - V

W - Z

C - D

E - F

G - H

I - J

K - L

S - T

Q - R

O - P

M - N


Index491

Location tableabout 102displaying 103reading information from file 105saving information to file 105

Locationsmodifying initial for parts 116positioning objects at 454viewing object 467

M - NMagnitude

calculating for multi-component forces 218defining for motion 179defining force 198modifying for multi-component forces 223modifying for single-component force 212

Manifold, defined 44

Markerscreating 21creating in Table Editor 412measuring distance between 122

Masscalculating aggregate 120modifying part 108point, creating 73

Mass moments of inertia, entering for parts 112

Massless beam, See Beams

Mate Faces tool, using 459

Materialssetting for parts 118specifying for beams 249standard types 118

A - B

U - V

W - Z

C - D

E - F

G - H

I - J

K - L

S - T

Q - R

O - P

M - N


Index492

Materials command, using 119

Mating, faces 459

Matricesdefining using data format 359defining using full format 354defining using result set components 358defining using sparse format 356format of data files for 360types of formats 352

Matrix command, using 354

MATSAV format, using with matrices 360

Measuring distance between markers 122

Merge tool, using 62

Merging rigid body geometry 62

MFORCEabout 265copying 269creating 266deleting 269modifying 269ways to define 265

Modal Force tool, using 266

Modal forcesSee MFORCE 265

Modal preloads, viewing 270

Modeling databaseapplying changes to through Table Editor 418reloading values in table from 418

A - B

U - V

W - Z

C - D

E - F

G - H

I - J

K - L

S - T

Q - R

O - P

M - N


Index493

Modelscopying 421tips on constraining 136using curve data elements in 328

Modify command, using 420

Modify dialog boxes, accessing 420

Modifyingaccessing dialog boxes for 420arcs and circles 88arrays 320beam 249boxes 92bushings 231cell information 417chamfering 101contact arrays 310coupler joint 169curve data element 329curve-on-curve cam 278cylinders 93differential equations 375extrusions 98field elements 259filleting 101force-based contacts 307frustums 95gear joint 166general state equations 383geometry, using dialog boxes 81–101geometry, using hotpoints 80holes and bosses 101hollowed objects 101joint motion 183linear state equations 378lines and polylines 87links 97

A - B

U - V

W - Z

C - D

E - F

G - H

I - J

K - L

S - T

Q - R

O - P

M - N


Index494

mass and inertia for rigid bodies 108matrixes 353–359MFORCE 269multi-component force 223part properties 106–117pin-in-slot cam 278planes 92plates 98revolutions 100simple joint 155single-component forces 212spheres 94splines 90spring-damper 235state variables 373torsion springs 241torus 96transfer functions 389

Motiondefining magnitude of 179degrees of freedom removed 131described 127, 177imposing on simple joint 161imposing point 186tips on creating 180types of 178

Motion generators, See Motion

Motion tool stackabout 134using 135

Move tool stackabout 440displaying 441

A - B

U - V

W - Z

C - D

E - F

G - H

I - J

K - L

S - T

Q - R

O - P

M - N


Index495

Movingabout tools for 440between cells and columns 344by aligning faces 459objects along their axes 445objects based on grid or features 456objects by aligning faces 459objects by dragging 442objects by increments 448objects from point to point 454objects in screen coordinates 469objects relative to/about coordinate system 464, 468objects to exact position 451objects using Precision Move dialog box, overview 461objects, about 439selecting reference coordinate system for 462

Multi-component forcescreating 221described 216displaying force graphics for 223force equations for 218modifying 223shortcuts for applying to parts 220torque equations 219

Multiple cells, inserting text into 103, 415

Nameschanging 425entering complete in cells 416of constraints 133of forces 200of parts 8

Narrowing columns in Location table 103

Nonconvex curves on cams 276

A - B

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Index496

Nonlinear forceabout specifying field element as 255defining field element as 259

Non-manifold, defined 44

Numeric sorting 410

O - PObject axes

rotating objects about their 446translating along 445

Object Color tool stack, using 437

Object position handleabout 443creating global 447displaying 444turning off global 447

Objectsabout selecting 392accessing modify dialog boxes 420activating 427adding holes and bosses to 59adding multiple to select list 398adding single to select list 397chamfering 57copying 421copying in Table Editor 411creating in Table Editor 412deleting 423deleting using Table Editor 413determining activation status of 430entering name in cells 416filleting 57grouping 431hollowing 60moving along their axes 445

A - B

U - V

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Index497

moving ground 7moving in screen coordinates 469moving relative to/about coordinate system 464, 468positioning precisely 451removing from select list 399removing multiple from select list 398renaming 425rotating about their axes 446rotating by increments 448rotating in screen plane 446selecting from crowd 395selecting one 393selecting several 394setting appearance of 433setting color of 437setting type displayed in Table Editor 404sorting in Table Editor 410translating by increments 450updating in select list 400

Open curves, specifying 327

Orientationmodifying initial, for parts 116of constraints 133

Orientation joint, creating 172

Outputs (Y) arrayscreating/modifying 320described 318determining size of 319

Pairs of force-based contacts 303

Parallel axes joint, creating 172

Parameterization, building in as you create parts 11

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Index498

PartsSee also Flexible LinksSee also Point MassesSee also Rigid Bodiesbuilding parameterization into 11calculating aggregate mass 120creating in Table Editor 412degrees of freedom, about 8ground 7how constraints connect 132modifying initial velocities 113modifying part properties 106–117naming 8setting up materials for 118tips on creating 9types of 6

Pasting text in cells 344

Perpendicular axes joint, creating 172

Pin-in-slot camcreating 275described 272initial conditions for 278modifying 278tips for 276

Pin-in-slot tool, using 275

Planar geometry and contacts 291

Planar jointcreating 153described 146modifying 155

Plane tool, using 34

Planescreating 34modifying 92

A - B

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Index499

Plate tool, using 42

Platescreating 41modifying 98

Plot view, in Spline Editor 338

Plottingmethods for Spline Editor 343splines 340

Point Mass command, using 74

Point masses, creating 73

Point motioncreating 187described 178, 186imposing on joint 161

Point tool, using 20

Pointscreating 18creating in Table Editor 412positioning objects to 454

Point-to-Point toolusing to move along a vector 455using to move from point to point 455

Polylinescreating 23modifying 87

Positioningflexible links 65objects based on grid or features 456objects by aligning faces 459objects by dragging 442objects by increments 448objects to a point 454objects to exact 451overview of 439

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Index500

Precision Move dialog boxabout 460moving objects in screen coordinates using 469moving objects relative to coordinate system using 464, 468overall procedure for 461selecting objects 462selecting reference coordinate system 462viewing locations of objects using 467

Preloadfor field element 260specifying for bushing 231specifying for spring-damper 235specifying for torsion spring 241

Preloads, viewing in flexible bodies 270

Prepend row to X & Y data button, using 346

Propertieschanging simple joint 157modifying part 106–117

Pt Cv cam, See Pin-in-slot cam

Q - RRatio of gear 165

Reading in Location table information 105

Recomputing, splines 343

Reference coordinate system, selecting 462

Reloading values in Table Editor 418

Removing rows in Spline Editor 346

Rename command, using 425

Renaming objects 425

Resetting values in Location Table 105

Reshaping geometry 80

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Index501

Resizingcolumns 103, 346geometry 80

Restitution-based contact, about 290

Result set components, defining matrix using 358

Revolute jointadding friction to 162creating 153described 142modifying 155setting initial conditions for 159

Revolution tool, using 48

Revolutionscreating 47modifying 100

Rigid bodiesabout 10accessing tools for creating 14adding features to 57–61creating complex 49–56creating construction 18–30creating solid 31–48merging geometry 62modifying mass and inertia 108modifying using dialog boxes 81–101modifying using hotpoints 80types of 13

Rotatingobjects about grid or features 456objects about their axes 446objects by increments 448objects to exact position 451objects, overview of 439

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Index502

Rotational motion tool, using 182

Rowsadding and deleting 104adding and removing in Spline Editor 346moving between 344

S - TSaving

Location table information 105Table Editor information 419

Screen coordinates, moving objects in 469

Screen icons, setting for objects 433

Screen planemoving objects in 445rotating objects in 446

Screw jointcreating 153described 148modifying 155

Searching, setting criteria for in Select List Manager 398

Select command, using 393

Select listadding multiple objects to 398adding single object to 397removing all objects from 399removing multiple objects from 398updating 400viewing groups in 400

Select List command, using 397

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Index503

Select List Manageradding objects to 398adding single object to 397displaying 397removing all objects from 399removing multiple objects from 398updating 400viewing groups in 400

Select toolusing to select one object 393using to select several objects 394

Selectingabout 392objects in crowd 395objects using Select List Manager 396one object 393several objects 394

Selection box, using 394

Settingpart materials 118view of Spline Editor 338

Shear area ratio, common values for 251

Simple jointchanging type of 157creating 153described 140imposing motion on 161modifying 155setting initial conditions 159types of 141–152

Simulationsactivating/deactivating objects during 427with force-based contacts 311

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Index504

Single point motioncreating 187described 186

Single point motion tool, using 188

Single-component Force tool, using 210

Single-component forcescreating 210described 205, 206displaying force graphics for 212modifying 212specifying direction of 208torque 207

Single-component Torque tool, using 210

Six-component general force vectorcreating 221described 216force calculations 218modifying 223torque calculations for 219

Six-component general force vector tool, using 221

Size, determining array 319

Slope, plotting 341

Solid geometryadding holes and bosses to 59chamfering 57creating 31–48creating one from two intersecting 54creating one from union of two 53cutting one solid from another 55described 13filleting 57hollowing 60modifying using dialog boxes 81–101modifying using hotpoints 80splitting 56

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Index505

Sorting objects in Table Editor 410

Sparse formatdefining matrix using 356described 352

Special forces, described 196

Specifying dimensions of splines 339

Sphere tool, using 36

Spherescreating 36modifying 94

Spherical jointadding friction to 162creating 153described 145modifying 155

Spline command, using 337

Spline data elementsediting data points in 342example of 333overview of 332plotting 341specifying dimensions in 339viewing slope (derivative) of 341ways to create 335

Spline Editoradding and removing rows 346changing plotting method 343derivative, plotting 341displaying 337editing data points in 342editing text in cells 344entering text in cells 344

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Index506

resizing columns 346selecting linear extrapolation in 340setting view of 338setting view of spline plot 341using tabular view 344viewing contents of cell 345

Spline General command, using 347, 350

Splinescreating 28creating from trace 77example of creating from trace 75modifying 90types of created from trace 76

Split tool, using 56

Splitting solid geometry 56

Spring-damperscreating 234described 233equations defining force of 234modifying 235specifying graphics for 235

State variablescautions with 372creating/modifying 373overview of 371ways to define 372

States (X) arraycreating/modifying 320described 318determining size of 319

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Index507

Static friction, adding to joints 162

Static simulations, controlling with system elements 369

Steps in defining curves 323

Stiffness and dampingmodifying for bushing 231specifying for beams 249specifying for spring-damper 235specifying for torsion spring 241

Stiffness coefficients, defining for field element 262

Stiffness matrix, defining for field element 262

String command, using 364

Subroutinecreating for motions 179defining for force 199

System elementsdifferential equations 374–376example of 368general state equations 381–385linear state equations 377–380overview of 365state variables 371–373terminology 370transfer function 386–390types of 367using arrays with 369using to control equilibrium 369

Table Editorapplying changes in 418copying objects in 411creating objects in 412deleting objects from 413described 401

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Index508

displaying 402entering complete object names in 416entering text in cells 415filtering information in 407inserting text into multiple cells of 415modifying cell information 417reloading 418saving information to file 419setting types of objects displayed in 404sorting objects in 410

Table Editor command, using 402

Tabular viewediting a spline in 344in Spline Editor 338

Terminology with system elements 370

Textediting in cells 344entering in cells 344, 415inserting into multiple cells 103, 415

Three-component force vectorcreating 221described 216force calculations 218modifying 223

Three-component torque vectorcreating 221described 216modifying 223torque calculations for 219

Three-component vector force tool, using 221

Three-component vector torque tool, using 221

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Index509

Three-dimensional splines, specifying 339

Tipson constraining your model 136on creating motion 180on creating parts 9

Tool stacksabout Motion 134about Create Forces 201about Geometric Modeling 14about Joint 134

Toolsaccessing constraint creation 134accessing force creation 201accessing rigid body 14for moving objects 440

Torqueabout specifying 216equations for multi-component forces 219

Torsion Spring tool, using 240

Torsion springscreating 240described 238equations for 238modifying 241

Toruscreating 38modifying 96

Torus tool, using 39

Tracecreating spline from 77example of creating spline from 75types of splines created from 76

Transfer Function command, using 389

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Index510

Transfer functionscreating/modifying 389details of 387overview of 386

Translatingobjects about their axes 445objects by dragging 442objects by increments 450objects from point to point 454objects to exact position 451

Translational jointadding friction to 162creating 153described 143modifying 155setting initial conditions for 159

Translational motion tool, using 182

Translational spring-damper, See Spring-dampers

Translational Spring-Damper tool, using 234

Transparency, setting object 433

Two-dimensional splines, specifying 339

Typesof arrays 318of data elements 316of flexible links 64of material 118of matrix formats 352of motion 178of objects in Table Editor 404of parts 6of spline geometry 76of system elements 367selecting objects based on their 396

A - B

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Index511

U - VUngroup command, using 432

Ungrouping objects 432

Union of geometry 53

Universal jointadding friction to 162creating 153described 151modifying 155

Updating select list 400

User-written subroutinecreating for motions 179defining for force 199using to define curve 327with arrays 318

Valuesediting in cells 344entering in Spline editor 344reloading in table 418resetting in Location Table 105

Vector, translating objects along 455

Velocitiesmodifying initial for parts 113specifying initial for curve-on-curve cam 279specifying initial for motions 183specifying initial for pin-in-slot cam 278

Viewinglocations of objects 467

Viewing contents of cell 345

Viscous damping coefficients, defining for field element 263

Visibility, setting object 433

A - B

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Index512

W - ZWidening columns in Location table 103

Window Layout tool stack 301

Wire geometrychaining 49extruding 50

Working grid, moving objects along 456

Documents

Building Models in ADAMS