ME 451

Introduction to ADAMS/View

VIRTUAL PROTOTYPING PROCESS

Build a model of your design using: Bodies Forces Contacts Joints Motion generators

Build Test Review Improve

Build Test Review Improve

VIRTUAL PROTOTYPING PROCESS

Test your design using: Measures Simulations Animations Plots

Validate your model by: Importing test data Superimposing test data

Build Test Review Improve

VIRTUAL PROTOTYPING PROCESS

Review your model by adding: Friction Forcing functions Flexible parts Control systems

Iterate your design through variations using: Parametrics Design Variables

Build Test Review Improve

VIRTUAL PROTOTYPING PROCESS

Improve your design using: DOEs Optimization

Automate your design process using: Custom menus Macros Custom dialog boxes

Coordinate Systems Definition of a coordinate system (CS)

A coordinate system is essentially a measuring stick to define kinematic and dynamic quantities.

P

x y zP P x P y P z

22222222222222

Types of coordinate systems Global coordinate system (GCS):

Rigidly attaches to the ground part. Defines the absolute point (0,0,0) of your

model and provides a set of axes that is referenced when creating local coordinate systems.

Local coordinate systems (LCS): Part coordinate systems (PCS) Markers

Coordinate Systems

Part Coordinate Systems Definition of part coordinate

systems (PCS) They are created

automatically for every part.

Only one exists per part. Location and orientation

is specified by providing its location and orientation with respect to the GCS.

When created, each part’s PCS has the same location and orientation as the GCS.

Markers

Definition of a marker It attaches to a part and

moves with the part. Several can exist per

part. Its location and

orientation can be specified by providing its location and orientation with respect to GCS or PCS.

Markers Definition of a marker (cont.)

It is used wherever a unique location needs to be defined. For example: The location of a part’s center of mass. The reference point for defining where graphical

entities are anchored. It is used wherever a unique direction needs to be

defined. For example: The axes about which part mass moments of inertia

are specified. Directions for constraints. Directions for force application.

By default, in ADAMS/View, all marker locations and orientations are expressed in GCS.

Difference between part and geometry

Parts Define bodies (rigid or flexible) that can move relative to

other bodies and have the following properties: Mass Inertia Initial location and orientation (PCS) Initial velocities

Geometry Is used to add graphics to enhance the visualization of a

part using properties such as: Length Radius Width

Is not necessary for most simulations.

Simulations that involve contacts do require the part geometry to define when the contact force.

Difference between part and geometry

Center of Mass Marker

Difference between part and geometry

Dependencies in ADAMS/View

Marker.mod.pend.mar_2

Marker.mod.pend.mar_1

Geometry.mod.pend.cyl

Marker.mod.pend.cm

Geometry.mod.pend.sph

Part.mod.pend

Model.mod

mar_1

cyl

cm sph

mar_2

Creating some parts

Link Box Sphere Extrusion Importing a geometry from CAD

package…. Parasolid…

Constraints

Definition of a constraint Restricts relative movement between parts. Represents idealized connections. Removes rotational and/or translational DOF

from a system. Joints

Revolute Translational Fixed Other…… ________________________

HMMWV Vehicle Model High Mobility Multipurpose Wheeled Vehicle (HMMWV)

modeled in ADAMS/Car

Track Model

Let’s create some mechanisms

Simple pendulum Parallelogram mechanism

Starting ADAMS/View Start ADAMS/View

Type “aview” hit enter Type “ru-standard” hit enter Type “i” hit enter

In the Welcome dialog box Under the heading, How would you like to proceed,

select Create a new model. Set some working directory. Name the model missilelauncher. Verify that Gravity is set to Earth Normal (-Global

Y). Verify that Units are set to MMKS - mm, Kg, N, s,

deg. Select OK.

The missile launcher model You will 1. construct a very simple parallelogram

mechanism used in a missile launcher by importing a simple geometry and creating rigid bodies and joints in ADAMS/View

2. Simulate the mechanism3. Create measure and add sensor4. Refine the model and simulate again5. PostProcess the results This will give you a rough idea about what

goes on in the world of virtual prototyping

Import a rough geometry for missile’s barrel Go to File import Select “Parasolid” as the

file format. Right click in the box next

to “File to Read” select “Browse” and point to barrel.x_t

Right click in the box next to Model name and select “missilelauncher”

Click OK Right click the barrel point

to Part:PART2 Rename Rename the part

to .missilelauncher.barrel

Importing Geometry

Setting up the working grid Note: Use “z” “r” and “t” keys

to Zoom, Rotate and Pan Go to Settings Working Grid Select “Pick” option from the

drop down menu for “Set Location”

Select the Center of lower left cylindrical hole on the face closest to you when the front of the barrel is pointing to +ve X direction.

See the figure on next slide

Setting up working grid

Setting up working grid

Go to View Coordinate Window (F4) Right click on Rigid Body Button in the

“Main Toolbox” Select Rigid Body: Link Click the origin of the grid to specify one

end of the Link and Click at location (550, -150, 0) to specify the other end of link Note: The coordinates of the locations can

be seen in the coordinate window Right click the link, point to Part:PART_3

Rename Rename the part as .missilelauncher.arm1

Creating rigid body: Links

Right click the link, point to Part:arm1 Copy This will create another Rigid Body of type “link” at

the same position as Part:arm1 The name of this newly created part will be

arm1_2 Right click the part, select Part:arm1_2 Rename Change the name to .missilelauncher.arm2 We want to move this newly created part from the

center of lower left cylindrical hole to the center of upper right cylindrical hole on the face closest to you when the front of the barrel is pointing to +ve X direction.

Creating rigid body: Links

Right click the position stack and select the translate tool as shown in the picture Note: The software will tell you what

you need to do next on the information bar at the bottom of the main window

Select the object to move: Right click the two parts (which are on top of each other)

This will give you option to select the part. Select arm2

The next prompt will be “select a point to move from”: here, select the center of lower left cylindrical hole on the face closest to you when the front of the barrel is pointing to +ve X direction

The next prompt will be “select the point to move to”: here select the center of upper right cylindrical hole on the face closest to you when the front of the barrel is pointing to +ve X direction.

Creating rigid body: Links

Create 4 revolute joints at locations shown

Creating Joints

Right click the joints stack in Main Toolbox and select Revolute Joint

Select following options 2 Body 1 Location Normal to Grid First body: Pick Body Second Body: Pick

body

Creating Joints

Joint 1: Revolute Joint between Ground and Arm1 Select Ground as the first body and Arm1 as the

second body Select the marker at the location (550, -150, 0) as the

location for the joint

Joint 2: Revolute Joint between Ground and Arm2 Select Ground as the first body and Arm2 as the

second body Select the marker on Arm2 corresponding to the

previously selected marker on Arm1 as the location for the joint

Creating Joints

Joint 3: Revolute Joint between Arm1 and barrel Select Arm1 as the first body and barrel as the

second body Select the marker at the location of the center of

lower left cylindrical hole on the face closest to you when the front of the barrel is pointing to +ve X direction

Joint 4: Revolute Joint between Arm2 and barrel Select Arm2 as the first body and barrel as the

second body Select the marker at the location of the center of

upper right cylindrical hole on the face closest to you when the front of the barrel is pointing to +ve X direction

Creating Joints

Applying Motion to Joint 1 Select Rotational Joint

Motion tool as shown in the figure

Click on Joint 1 This will add a rotational

motion to the joint

Applying motion to Joint

Right click on the motion and point to Motion:MOTION_1 Modify

This will launch modify motion box as shown

Enter -30.0d * time as the Function of time (note the –ve sign)

Applying motion to Joint

Click on “Interactive Simulation controls”

Enter 5.0 sec for End Time and enter 500 for number of Steps (see the figure)

Select the play tool This will run a simulation

and the mechanism will turn through 150 degrees and will stop (why 150 degrees?)

Running initial simulation

We want the mechanism to stop when the Arms are vertical and the barrel is at maximum height

To achieve this we will create a “Sensor” which will stop the simulation as soon as the links are vertical

The Sensor needs to keep track of some value/measurement, so that it can stop the simulation when this measure reaches some particular value

So there are 2 steps1. Create a Measure2. Create a Sensor based on this measure

Need for Measures and Sensor

We will create a measure to track the Horizontal Distance between these two points

We know that the arms will be vertical when this distance will become zero (this is exactly what the sensor will look for)

Measure

Go to Build Measure Point-to-Point New

Measure

Give the measure name .missilelauncher.for_vertical_sensor

Right click in the box next to “To Point” and select arm1.Marker_1 (the marker at the location of the center of lower left cylindrical hole on the face closest to you when the front of the barrel is pointing to +ve X direction)

Right click in the box next to “From Point” and select arm1.Marker_2 (the marker at the location (550, -150, 0))

Select “Translational Displacement” as characteristic Component : X Select “Create Strip Chart” and hit OK

Measure

Building a Sensor Go to Simulate Sensor

New Name the

Sensor .missilelauncher.vertical_sensor

Select Run-Time expression for Event Definition

Click next to the Expression box

This will launch Function Builder

Sensor

Delete anything that is seen here

Select “Measures” for Getting Object Data

Right Click in the box and point to Runtime Measures Guess for_vertical_sensor

Then hit Insert object name and click OK

Sensor

Now will be back to Create Sensor dialog box

Set event evaluation to None

Select Non-Angular Values Select Equal Enter value as “0” Set the Error Tolerance as

1.0E-05 Check Terminate current

simulation step and... Check Stop Hit OK

Sensor

Now again run the simulation for 5 seconds with 500 steps and verify that the simulation stops when the arms are vertical

Sensor

Adjust the barrel mass Right click the barrel Point to Part:barrel Modify Select Define Mass by “User input” Enter 100kg next to Mass Hit OK

Refining the model

Run the simulation for 5 seconds with 500 steps and post process the results

To launch the post Processor Go to Review PostProcessing (F8) Select Objects as source and review the

results

Final Simulation and PostProcessing

Application of this virtual prototyping One can review forces coming on joints,

and hence select appropriate bearings Torques acting at the joints can be found

and hence an appropriate motor can be selected based on the operating speed and torque requirements

A controls module can be added and tested All mass properties, geometries, operating

speeds etc can be changed and their effects can be evaluated

Applications