PVDesigner   

PVDesigner is a program in Autodesk Simulation that allows you to easily create intersecting cylinders or, more specifically, pressure vessels. This package will take the specifications (dimensions) you give it and will create a meshed model of either plate elements or bricks. Figure 1 shows the interface.

Figure 1: PVDesigner Interface

1. Title Bar: The Windows standard title bar displays the program name and the model name.

2. Menu Bar: The menu bar is located just below the title bar and contains the pull-down menus.

3. Toolbars: The dockable toolbars provide you with quick access to many PVDesigner commands. Use the View Toolbars command to choose which toolbars to display.

4. Input Area: The input area is where you enters the dimension of the various segments of the vessel. Some input is also entered in pop-up dialog windows.

5. Preview Area: The Preview Area shows the model as it is being built.

6. Miniaxis and Scale Ruler: The miniaxis shows your viewpoint with respect to the three dimensional working area and the scale ruler shows the relative size of the model. Use the Model Preferences MiniAxes/Dimension Scale command to control the visibility of these items.

7. Status Bar: The status bar displays important messages about the model. For example, attempting to place a 5 foot diameter nozzle on a 3 foot diameter vessel will generate a warning about the sizes. Keep an eye on the status bar.

To access PVDesigner, click New. Double click the PVDesigner icon. The PVDesigner dialog box will appear after you select a filename, analysis type and unit system.

Once a mesh has been created with PVDesigner, the input parameters (cylinder size, nozzle dimensions, and so on) can be modified by using the Tools Edit Pressure Vessel command. When finished in PVDesigner, any previously defined input in the user interface (Element Definition, loads, hand-built parts, and so on) will be retained and merged with the new mesh of the vessel. Note

Only one vessel per model can be created as PVDesigner puts the same vessel into all design scenarios.

The input for PVDesigner uses the Model Units. Activating a different Display Units before modifying the vessel with Tools Edit Pressure Vessel has no effect.

TipPVDesigner mesh may change when a vessel is modified. We recommend that you confirm that any hand-built geometry still matches the modified vessel. For example, the mesh for a hand-built support which was added to the original vessel may need to be adjusted to match the new mesh on a modified vessel.

Capability Single Nozzle Vessel Multiple Nozzles Vessel

  Model  

Plate or Shell elements Yes (mesh or IGES file) Yes (mesh or IGES file)

Solid elements Yes (mesh or IGES file) Yes (mesh only)

  Main Cylinder  

Create vessel with no nozzle Yes Yes

Tapered cylinder No (use Additional Length on head) Yes

Zero length cylinder No Yes

Partial cylinder in hoop direction Yes No

Flanges on main cylinder Yes Yes

  Nozzles  

Nozzle types on cylinder Round Round, Elliptical, Rectangular

Repad at each nozzle Yes Yes

Feature region at nozzle Yes No

Nozzle on heads Yes Yes

Nozzle types on heads Round, Elliptical, Rectangular

Round, Elliptical, Rectangular

Tapered Nozzle On heads only Yes, main cylinder and heads

  Heads  

Heads on cylinder Yes Yes

Heads on nozzle Yes Yes

Truncated Cone Yes (use tapered additional length)

Yes (use tapered additional length)

In many cases, complex vessels can be created with a single PVDesigner model by using a combination of the main cylinder, nozzles, heads, and nozzles on the heads. In other cases, multiple models can be created with PVDesigner and merged together in Autodesk

Simulation. (Create each model separately, then use Merge.) Examples are shown in Figures 2 and 3.

 

  

Figure 2: Spherical Vessel with Multiple Nozzles

   

1. Nozzle on head - A flange is added to the end of the nozzle.

2. Head on cylinder - A tapered additional length is added between the elliptical head and the cylinder.

3. Flange on cylinder - The cylinder is tapered. One nozzle is tapered and has a head. The head has a nozzle. One nozzle is elliptical and created as an orifice; that is, a hole in the side.

4. Main cylinder with multiple nozzles - A tapered additional length is added between the elliptical head and the cylinder.

5. Flange on cylinder

6. Head on cylinder - An additional length is added between the conical head and the cylinder.

7. Nozzles on head

 Figure 3: Example PVDesigner Vessel with Multiple Nozzles and Heads

The steps to create a vessel with a single nozzle are slightly different than the steps to create a vessel with multiple nozzles (such as Figure 1).

Topics in this section

Pressure Vessels With Single Nozzles

Pressure Vessels With Multiple Nozzles

Heads Dialog Box

Nozzles on Heads

Preview Properties Dialog Box

Clipping Planes Settings Dialog Box

Other Menus in PVDesigner

Pressure Vessels With Single Nozzles   

If the vessel has a single nozzle projecting from the main cylinder (or no nozzle), then set the Type of model to generate drop-down box in the General tab to Single nozzle.

To generate a plate or shell element model, select the Plate/shell option in the Type of pipes generated drop-down box on the General tab. To generate a brick element model, select the Solid option. Note that the Preview Area does not show the thicknesses; it continues to show the plate/shell mesh. NoteFor plate/shell meshes, the diameters entered are to midplane of the plate. Thus, a 48 inch diameter vessel with a wall thickness of 0.5 inch results in a cylinder with a 47.5 inch inside diameter and a 48.5 inch outside diameter. For solid meshes, the diameters entered are the outside dimensions. Thus, a 48 inch diameter vessel with a wall thickness of 0.5 inch results in a cylinder with a 47 inch inside diameter and a 48 inch outside diameter.

Main Cylinder

The main dimensions of the cylinder will be defined in the Geometry tab. The pressure vessel is always drawn with the axis of the cylinder along the X axis, and any nozzle specified intersects the cylinder at the YZ plane; that is, at X=0. The total length of the cylinder is specified with two values: the length on the positive side of the nozzle intersection, and the length on the negative side of the nozzle intersection; that is, in the positive X and negative X directions.

If the pressure vessel does not consist of an entire cylinder, set the Angular extent of cylinder drop-down box to one of the following. Otherwise, leave the setting at Full 360 degree sweep for a complete vessel.

The Measured using angles relative to Z-axis option starts the measurements from the Z axis regardless of where the nozzle is located.

The Measured using angles relative to intersection option starts the angular measurements from the intersection of the nozzle and cylinder. This option has a difference only if the nozzle is offset from the XZ plane. (See below.)

Specify the corresponding angles in the Angular extent in negative direction and Angular extent in positive direction fields. The angles follow the right-hand rule, so the angle in the negative direction goes about the -X, and the angle in the positive direction goes about the +X axis.

To create a pressure vessel with no nozzles, activate the Create model without nozzle check box on the General tab.

Nozzle on the Main Cylinder

The intersection of the nozzle axis and the cylinder will be located in the YZ plane. The default axis of the nozzle will be collinear with the Z axis and will intersect the cylinder along the cylinder axis. This is controlled by the options in the Pipes Intersect at drop-down box on the General tab.

The 90 degrees - T junction option specifies that the nozzle is collinear with the Z axis, there by forming a 90 degree angle.

Use the Along specified direction option to rotate the axis of the nozzle about two directions to create an offset nozzle. When this option is chosen, the Intersection tab is used to specify the offsets.

The Offset of nozzle specified using drop-down box on the Intersection tab is used to specify how to specify the offset out of the XZ plane. If the Distance option is selected, specify the location along the Y axis where the nozzle intersects the cylinder in the Nozzle's offset distance (DY) field. If the Angle option is selected in the Offset of nozzle specified using drop-down box, specify the angle at which the nozzle intersects the cylinder in the Angular offset of nozzle's axis (ADY) field. See Figure 1. Note that the nozzle is still parallel to the XZ plane. Note that this value follows the left-hand rule, so a negative angle rotates the nozzle about the +X axis.

 

 

Offset of nozzle by distance Offset of nozzle by angle

Figure 1: Offset of Nozzle

For both cases, the nozzle can be rotated about the Y axis so that it is not parallel to the Z axis. Specify the angle in the Angular rotation of nozzle about Y-axis (AR) field. Note that this value follows the left-hand rule, so a negative angle rotates the nozzle about the +Y axis.

Figure 2: Rotation of Nozzle About Y Axis

A positive angle is shown. Note that the angle follows the left-hand rule.

The length of the nozzle, inside and outside of the cylinder, are specified on the Geometry tab using the Length of nozzle (L2) and Nozzle's length inside cylinder fields, respectively.

Nozzles on Heads

After a head is added to the main cylinder or to a nozzle on the main cylinder (see below), a nozzle can be added to the head! On the Heads dialog where the head is defined, activate the check box Include nozzles on head, and then click the Nozzles on head button. Refer to the page Nozzles on Heads for details.

Flanges, Repads, and Feature Regions

Flanges can be added at either end of the cylinder and at the end of the nozzle. Repad can be added at the intersection of the nozzle and cylinder. The widths of these features can be specified in the Flanges/Repad tab. Activate the check boxes for the features that you want to add and specify the desired width in the corresponding field.

A feature region is a layer of elements surrounding the nozzle and cylinder intersection (see Figure 3). It could be used for additional reinforcement, a region of constant width, or as a region to hide/show the elements and stresses near the intersection. The following steps are used to create a feature region:

1. Go to the Model Mesh command.

2. Set the Meshing method drop-down to All increments specified.

3. Use the Feature Region tab to enable and then set the dimensions and part numbers for the feature regions.

4. Once the feature region is enabled, the Meshing method drop-down can be changed to another method if desired.

Add Heads to the Cylinder and Nozzle

If the pressure vessel has heads on either end of the cylinder or on the nozzle, specify these with the Model Heads dialog. See the page Heads Dialog for details.

Set Part Numbers

Each piece of the vessel - cylinder, nozzle, repads, and so on - can be created on a different part number. Recall that the part number controls parameters such as the material properties, and for plate/shell models, the thickness of the part and which side is top and bottom for pressure loading.

You can control the part number into which each piece is placed in the Parts dialog by accessing the MODEL pull-down menu and selecting the Parts command. When creating a solid mesh, use the Solid mesh composed of drop-down on the General tab to choose between creating the solid mesh on a single specified part number or on multiple parts.

Set Mesh Density

You can control the mesh spacing used for each part of the pressure vessel in the Mesh Parameters dialog by accessing the MODEL pull-down menu and selecting the Mesh command. When the Meshing method drop-down is set to Only transition parameters NHTX specified or Only transition parameters NHTT specified, you will only be able to control the mesh size in one direction (NHTX or NHTT) of the transition area where the nozzle meets the cylinder. The rest of the mesh is based on the single input for the transition region mesh size.

To control the mesh in all areas of the model, select the All increments specified option in the Meshing method drop-down box. Go to the appropriate tab for the mesh that you want to specify.

Most of the input is a straight forward number of how many elements are desired along a particular dimension. Those numbers then propagate to other areas of the vessel. For example, NHTT and NHTX determine how many elements are around the perimeter of the nozzle and any head placed on the nozzle. (See Figure 3.) Other parameters on the Mesh Parameters dialog are clarified below.

The Transition Size tab controls how large the transition region is around the nozzle. (See Figure 3.) Separate controls are used for the axial direction and the sweep (or hoop) direction. When the Extent in _ direction defined using is set to Ratio, then the ratio of the size of the transition region to the intersection is specified. The extent ratio equals NX/diameter of nozzle and NT/diameter of nozzle (for the axial and hoop directions, respectively). If a repad or feature region is included, then the lengths NT and NX are outside the repad or feature region, whichever is larger. When no repad or feature region exists, then the lengths NT and NX are measured from the nozzle. When the Extent in _ direction defined using is set to Absolute _, the inputs of Axial direction length and Sweep direction angle correspond to NHTX and NHTT, respectively.

TipIn addition to creating a structured mesh by setting the parameters on the Mesh tab, a nonstructured mesh can be created if you own the ability to mesh CAD models. Use the PVDesigner File Export command and set the Save as type to Solid

(*.igs). Then after exiting PVDesigner to return to Autodesk Simulation, use the Open command and set the Files of type to IGES. Once the IGES file is opened,

set the mesh type as appropriate (either Solid or Plate/shell) and mesh the model.

Define Thickness

If you are creating a brick model, the thickness of each part can be specified in the Solid Thickness dialog by accessing the MODEL pull-down menu and selecting the Thickness command. (For plate/shell meshes, the thickness of each region is specified in the FEA Editor under the Element Definition.) NotePVDesigner does not show the thickness of the pieces in the Preview Area. This is only shown in Autodesk Simulation after you exit PV/Designer.

 

Key: 1 = nozzle mesh 2 = optional feature region on the nozzle 3 = optional feature region on the cylinder 4 = optional repad on the cylinder 5 = transition region on the cylinder NHTX = half the axial length of the transition region NX = distance between nozzle (or repad or feature region if it exists) and end of transition region in the axial direction NHTT = half the sweep length of the transition region NT = distance between nozzle (or repad or feature region if it exists) and end of transition region in the sweep direction

Figure 3: Transition Mesh Between Nozzle and Cylinder

Pressure Vessels With Multiple Nozzles   

If the vessel has multiple nozzles projecting from the main cylinder, then set the Type of model to generate drop-down box in the General tab to Multiple nozzles. This will deactivate the other tabs. The input is used only for a single nozzle vessel.

To generate a plate or shell element model, select the Plate/shell option in the Type of pipes generated drop-down box on the General tab. To generate a brick element model, select the Solid option. Note that the Preview Area does not show the thicknesses; it continues to show the plate/shell mesh. NoteFor plate/shell meshes, the diameters entered are to midplane of the plate. Thus, a 48 inch diameter vessel with a wall thickness of 0.5 inch results in a cylinder with a 47.5 inch inside diameter and a 48.5 inch outside diameter. For solid meshes, the diameters entered are the outside dimensions. Thus, a 48 inch diameter vessel with a wall thickness of 0.5 inch results in a cylinder with a 47 inch inside diameter and a 48 inch outside diameter.

The input for a multiple nozzle vessel is entered by pressing the Multiple nozzles button. This will display the Cylinder with Multiple Nozzles input dialog. TipUse the Model Dialog Position menu to control where this input screen (and the other dialogs) first appear on the screen.

Main Cylinder

On the Geometry tab, specify the length, diameter (at -X end of cylinder) and taper angle of the cylinder. The centerline of the cylinder is on the X axis, and the end on the -X side is at the origin. The taper angle is defined as tan(angle a)=[0.5*(End Diameter - Diameter of cylinder)/(Length of cylinder)]. A positive taper angle means that the diameter is larger at the +X end of the cylinder than at the end specified (Diameter of cylinder (D1)).

 

Key: D = diameter of cylinder (user input) De = end diameter (calculated) L = length of cylinder (user input)

= taper angle (user input). Tan() = (De - D)/2/L

  Figure 1: Tapered Cylinder

Nozzles on Main Cylinders

Since the main cylinder can contain multiple nozzles, the following buttons on the Cylinder with Multiple Nozzles input dialog are used to manipulate the various nozzles:

To create a nozzle on the cylinder, press the Add new nozzle button in the Geometry tab. Once you are done defining the nozzle, press the Add new nozzle button again to create the next nozzle. Repeat this until all nozzles have been added.

To modify the properties of an existing nozzle, select the nozzle number in the drop-down box in the Nozzles on Cylinder section and press the Modify nozzle button.

To remove a nozzle, select the nozzle number in the drop-down box in the Nozzles on Cylinder section and press the Remove nozzle button.

If two nozzles are identical but are located at different positions, you can define the nozzle properties for one nozzle, select the nozzle number in the drop-down box in the Nozzles on Cylinder section and press the Duplicate nozzle button. A new nozzle will be created. You can then modify the position of the new nozzle.

When editing a particular nozzle (either when adding a new nozzle or modifying an existing nozzle), the Particular Nozzle dialog specifies all of the parameters for the position, size, heads on the nozzle, and so forth. The input is mostly self explanatory with the following clarifications:

Use the Include nozzle on cylinder check box to activate or deactivate the nozzle. Deactivating the nozzle will hide it but retain the input.

The Geometry tab gives the dimensions of the nozzle. Also,

Taper angle of nozzle: Since the input diameter for the nozzle is at the end away from the intersection with the cylinder, a positive taper angle means that the nozzle is larger at the cylinder intersection than the opposite end. Using the nomenclature in Figure 1, Tan() = (De - D)/2/L where D is the user-entered diameter or dimension and De is the diameter or dimension of the nozzle at the cylinder.

Orifice with no nozzle will create a hole in the side of the vessel using the nozzle type and dimensions.

The Position tab is used to locate the nozzle on the cylinder.

X value is measured from the -X end of the cylinder.

X rotation follows the left-hand rule to rotate the nozzle about the X axis to the point of intersection. That is, a negative angle rotates the nozzle about the +X axis. The Offset method then moves the nozzle off of the X rotation axis. See Figure 2.

The Offset method drop-down box is used to indicate how to specify the offset of the nozzle out of the plane of the X rotation. (If the X rotation were 0, the offset would be in the Y direction.) If the Distance option is selected, specify the distance perpendicular to the X rotation plane in the Nozzle's offset distance (DY) field. If the Angle option is selected in the Offset method drop-down box, specify the angle at which the nozzle intersects the cylinder in the Nozzle's offset angle (ADY) field. See Figure 2. This value follows the left-hand rule, so a negative angle rotates the nozzle about the +X axis.

 

 

Offset of nozzle by distance Offset of nozzle by angle

Note that the nozzle centerline is parallel to the centerline defined by the X rotation angle. When the offset is 0, the nozzle is perpendicular to the vessel. When the offset is nonzero, the nozzle is no longer perpendicular to the vessel. By using a combination of X rotation and offset, a nozzle can be created with any desired orientation.

   

Example Vessel with known position of nozzle at angles and .

Input into PVDesigner. X rotation = -. ADY = .

The nozzle can be rotated about the Y axis so that it is not parallel to the YZ plane. Specify the angle in the Angular rotation of nozzle (AR) field. Note that this value follows the left-hand rule, so a negative angle rotates the nozzle about the +Y axis. See Figure 3.

Figure 3: Rotation of Nozzle About Y Axis.

A positive angle is shown. Note that the angle follows the left-hand rule.

Nozzles on Heads

After a head is added to the main cylinder or to a nozzle on the main cylinder (see below), a nozzle can be added to the head! On the dialog where the head is defined, activate the check box Include nozzles on head, and then click the Nozzles on head button. Refer to the page Nozzles on Heads for details.

Flanges and Repads

Flanges can be added to either end of the cylinder from the main Cylinder With Multiple Nozzles dialog. From there, use the Extras tab to specify the parameters for the flanges.

Flanged can be added to the end of a nozzle. Modify the nozzle of interest to display the Particular Nozzle dialog, then go to the Extras tab. Enter the desired dimension.

Repads around the nozzle to main cylinder intersection are also added from the Extras tab for the appropriate nozzle; that is, modify the nozzle of interest to display the Particular Nozzle dialog, then go to the Extras tab.

Add Heads to the Cylinder and Nozzles

Heads can be added to the cylinder from the main Cylinder With Multiple Nozzles dialog. Go to the Extras tab and click the Heads button. This will access the Heads on Cylinder dialog.

Heads can be added to the end of any nozzle attached to the main cylinder. Modify the nozzle of interest to display the Particular Nozzle dialog, then go to the Heads tab.

Whether adding a head to the cylinder or a nozzle, the input is similar. See the page Heads Dialog for details.

Set Part Numbers:

Each piece of the vessel (cylinder, nozzle, repads, and so on) can be created on a different part number. Recall that the part number controls parameters such as the material properties, and the thickness of the part and which side is top and bottom for pressure loading (for plate/shell models).

Part numbers for the cylinder are specified from the main Cylinder With Multiple Nozzles dialog. From there, use the Parts tab.

Part numbers for each nozzle are specified by modifying the nozzle of interest to display the Particular Nozzle dialog, then go to the Parts tab.

Set Mesh Density

You can control the mesh spacing used for each part of the pressure vessel. For the main cylinder, flanges and heads on the cylinder, go to the Mesh tab on the main Cylinder With Multiple Nozzles dialog.

For the mesh around the nozzles, transition region, flange, repad, and heads on the nozzle, modify the nozzle of interest to display the Particular Nozzle dialog, then go to the Mesh

tab. In addition to specifying the number of divisions, the size of the transition region around the nozzle to cylinder intersection is controlled by the Ratio of transition to cylinder diameter input. The dimension of the transition region, measured from the nozzle (or edge of the repad if included), is equal to or greater than the ratio input value times the cylinder diameter. The actual dimension of the transition region is adjusted to fit the mesh on the cylinder. See Figure 4.

 

Key: 1 = nozzles on head 2 = head on nozzle 3 = nozzle on cylinder 4 = optional repad on the cylinder 5 = transition region on the cylinder NX = distance between nozzle (or repad if it exists) and end of transition region in the axial direction. NX>=Ratio*cylinder diameter. NT = distance between nozzle (or repad if it exists) and end of transition region in the sweep direction. NT>=Ratio*cylinder diameter.

  Figure 4: Transition Mesh Between Nozzle and Cylinder

To create a nonstructured mesh, you must own the ability to mesh CAD models, then:

1. Use the PVDesigner File Export command and set the Save as type to Solid (*.igs).

2. Exit PVDesigner to return to Autodesk Simulation.

3. Use Open and set the Files of type to IGES.

4. Once the IGES file is opened, set the mesh type as Plate/shell and mesh the model.

NoteThe File Export command does not create a solid IGES file of a solid multiple nozzle type, only the plate/shell multiple nozzle type.

Define Thickness

If you are creating a brick model, the thickness of each part can be specified on the appropriate Thickness dialog. For example, the dialog for entering the main cylinder dimensions includes a Thickness tab, the dialog for entering the main cylinder nozzle dimensions includes a Thickness tab, and the dialog for entering the nozzle on a head includes a Thickness tab. (For plate/shell meshes, the thickness of each region is specified in the FEA Editor under the Element Definition.) NotePVDesigner does not show the thickness of the pieces in the Preview Area. Thickness is shown in Autodesk Simulation after you exit PVDesigner. NoteThe actual thickness of the mesh on the main cylinder and heads may be smaller than the user-specified dimension at nozzle intersections. This occurs when the transition region's dimension or number of divisions is too small. This situation can only be seen in the FEA Editor (or Results Environment after performing a Check Model). If it occurs, return to PVDesigner (Tools Edit Pressure Vessel), then modify the nozzle (Multiple nozzles Modify Nozzle). If the problem occurs with the nozzle to main cylinder intersection, use the Mesh tab to increase the Ratio of transition to cylinder diameter or Mesh division along width of transition region. If the problem occurs with the nozzle to head intersection, use the Heads tab, then Nozzles on head button, then Mesh tab to increase the Transition region ratio or Mesh division along width of transition region.

Heads Dialog Box   

Activating the command:

Model Heads for single nozzle vessels

Multiple nozzles Extras tab, then Heads for heads on cylinder (multiple nozzle vessels)

Multiple nozzles Geometry tab, then Modify for heads on nozzle (multiple

nozzle Heads tab nozzle vessels)

There are multiple types of heads that can be added to either end of the cylinder or to the end of a nozzle. This is selected in the Type of head drop-down box. See Figure 1.

If the Flat option is selected, a flat plate will be created at the end.

If the Spherical option is selected, you must specify a value in the Diameter field. A hemispherical head is created if the diameter equals the diameter of the cylinder or nozzle. Otherwise, a sector of a sphere is created.

If the Ellipsoidal option is selected, you can define the dimensions of the heads using three options available in the Input type for ellipsoidal head uses drop-down box.

If the Direct input of diameter and height option is selected, you must specify these parameters in the Diameter and Height fields. If the diameter of the head is greater than the diameter of the cylinder, the connection will have a sharp bend. If the two diameters are equal, the connection will be flush.

If the Rotation angle option is selected, you must specify values in the Diameter and Rotation Angle fields. This option will use a projection of a circle of the specified diameter, which has been rotated about an axis perpendicular to the length of the cylinder. A value of 0 will result in a spherical head. A value of 90 will result in a flat head.

If the Ellipsoidal ratio option is selected, you must specify a value in the Ellipse Ratio field. This value is the ratio of the radius to the height of the head where the radius is half of the cylinder diameter. This option will always create a smooth connection between the cylinder and head.

If the Torispherical option is selected, you must specify values in the Spherical radius (I.D.R.) and Knuckle radius (I.C.R.) fields. The torispherical geometry is formed from two curves. The spherical radius is the larger of these two curves and is used toward the center of the head. This value should be larger than the radius of the cylinder. The knuckle radius is the smaller of these two curves and is used around the edge of the head. This value should be smaller than the radius of the cylinder.

If the Conical option is selected, you can specify a value in the Height field. If the Height is 0, then a flat head is created.

Elliptical Heads D = Diameter; H = Height

Torispherical Head I.D.R. = Spherical radius; I.C.R. = Knuckle radius

Conical Head H = Height

Figure 1: Cross-Section of Various Heads

Any of the heads, except for the flat head, can be concave or convex. This is controlled by the option selected in the Orientation of head drop-down box.

If you need to extend the cylinder (or nozzle) before the head is attached, specify this distance in the Additional length field. To create a reducer, specify a taper angle in the Taper angle of the additional length field. A positive angle will reduce the diameter from the cylinder or nozzle diameter towards the head. Tan(a) = (D - Dh)/2/L where D is the diameter of the cylinder or nozzle and Dh is the diameter at the end with the head.

If the head has nozzles attached to it, activate the Include nozzles on head check box and then press the Nozzles on head button. Refer to the page Nozzles on Heads for details.

Nozzles on Heads   

After a head is defined, either on the end of the main cylinder or on a nozzle, then multiple nozzles can be added to the head. Activate the check box Include nozzles on head and click the Nozzles on head button. This will display the Nozzles on Head dialog.

The Nozzle on head drop-down will show the input for the selected nozzle. Click the Add nozzle button to add another nozzle to the head. Click the Remove nozzle button to delete the currently selected nozzle. The Duplicate nozzle button will copy the existing nozzle in case the vessel has similar nozzles; simply change the parameters that make the duplicate nozzle unique.

The input for nozzles on heads is mostly self explanatory with the following clarifications:

Geometry tab

When creating a solid mesh, the diameters are to the outside of the nozzle. The thickness extends inward.

Orifice with no nozzle will create a hole in the side of the head using the nozzle diameter.

Taper angle of nozzle: Since the input diameter for the nozzle is at the end away from the intersection with the head, a positive taper angle means that the nozzle is larger at the intersection than the opposite end. Using the nomenclature in Figure 1, Tan() = (De - D)/2/L where D is the user-specified diameter and De is the diameter of the nozzle at the head.

Use the Include nozzle on head check box to activate or deactivate the nozzle. Deactivating the nozzle will hide it but retain the input.

 

Key: D = diameter of nozzle (user input) De = diameter at intersection of head L = length of nozzle (user input) = taper angle (user input). Tan() = (De - D)/2/L

Figure 1: Tapered Nozzle

Position tab

See Figure 2 for a definition of the values that position the nozzle.

The Intersection is based on drop-down determines whether the dimensions are based on the Actual head or the theoretical Flat head; that is, the end of the cylinder. For example, if a nozzle on the end of a cylinder is parallel to the axis of the cylinder (Phi angle=0), and if the nozzle length is 5 feet, then the end of the nozzle will be 5 feet from the cylinder when using Intersection is based on: Flat head regardless

of the offset distance. When using Intersection is based on: Actual head, the distance from the end of the nozzle to the cylinder depends on the dimensions of the head, the offset distance, and so on.

When activated, Normal to the head calculates the Phi angle and Theta angle so that the nozzle is perpendicular to the head.

End View of Head Nozzle not shown for clarity

Cross Section View Nozzle intersection based on actual head.

Cross Section View Nozzle intersection based on flat head. Only the portion of the nozzle beyond the actual head is created.

Key: OA = Offset angle OD = Offset distance L = length of nozzle = Phi angle = Theta angle.  

Figure 2: Positioning a Nozzle on a Head

Thickness tab

If you are creating a brick model, the thickness of each part or the nozzle can be specified in the Thickness tab. (For plate/shell meshes, the thickness of each region is specified in the FEA Editor under the Element Definition.) NotePVDesigner does not show the thickness of the pieces in the mesh. Thickness is shown in Autodesk Simulation after you exit PVDesigner.

Preview Properties Dialog Box   

Activating the command: Model Preferences.

Enable Model Preview: Deactivating this check box causes the preview area to not show the model you are building.

OpenGL Info: Pressing this button displays the OpenGL information for your system.

General Tab

Use Hardware Acceleration: If this check box is activated, the dynamic viewing options in the preview area will utilize any hardware acceleration software that is available on your system.

Use Animation when Zooming/Pre-defined Views: If this check box is activated, the preview area will dynamically move to any of the selected pre-defined views.

Decrease Quality wile Rotating/Zooming Model: Activating this check box will change the shading of the model as you rotate it or zoom in or out. This may speed up the viewing process on some systems.

Display Border: Activating this check box will cause a border to appear around the preview area.

Shrink Elements: Activating this check box will cause the elements in the model to be shrunk in the preview area so that you can see the model more clearly. Specify how much you want the elements to be shrunk using the Shrink Factor slider.

Mesh Line Smoothing: Activating this check box will cause the mesh lines on your model to be smoothed over with OpenGL anti-aliasing.

Mesh Line Width: You can specify between Thin, Medium and Thick mesh lines on your model.

MiniAxes / Dimension Scale Tab

Display MiniAxes: Deactivating this check box will cause the miniaxes to disappear from the view.

MiniAxes Location: You can choose where in the window you want the miniaxes display to be.

Display Dimension Scale: Deactivating this check box will cause the scale bar to disappear from the view.

Scale Location: Choose where in the window the scale bar will be displayed.

Clipping Planes Settings Dialog Box   

Activate the command: Model Clipping Planes.

Using this dialog box, you can specify slice planes so that you can view the interior of your model.

You can use any combination of the three global planes and a user defined plane to slice your model.

Enable: Activating this check box will cut your model using the respective plane going through the origin. The part of the model on the negative side of the plane will be hidden. Moving the slider bar to the left will move the plane to the negative side of the origin. Moving the slider bar to the right will move the plane to the positive side of the origin.

Invert: Activating this check box will cause the part of the model on the positive side to be hidden.

For the Custom plane, specify the components of the vector that is normal to the plane using the X:, Y:, and Z: input fields. To specify the normal direction, activate the Enable box, change the values, deactivate (clear) Enable, and then activate Enable again to use the new input values.

Other Menus in PVDesigner   

File Pull-Down Menu

Once the pressure vessel is created, in addition to loading the model into the FEA Editor environment, you can export the geometry to either xml, igs. or Excel file

format using the Export command. The igs format will be a trimmed surface file which is usually associated with solid models, but it works well for plate/shell models, too.

Selecting the Print command will print the current image in the display area.

Select the Done command to load the model into the FEA Editor environment.

View Pull-Down Menu

The Mesh Only command will display an unshaded wireframe of the model.

The Shaded Mesh / New Style command will display the model shaded according to part number with back mesh lines.

The Shaded Mesh / Old Style command will display the model shaded gray with the mesh lines colored according to part number.

The Shaded Only command will display the model shaded according to part number with no mesh lines.

The Show Dimensions command can be used to toggle the display of the dimension names on and off in the Preview area. The dimension names correspond to the variables shown after the text label in the Input area. Use the Model Colors command to set the color used for the dimension names.

The command in the Mouse Mode pull-out menu can be used to manipulate the view in the preview area. When the cursor is in the preview area, the shape reflects the selected command. The commands are:

Rotate: dynamically rotate the model by holding the left mouse button and dragging the mouse around the screen. An alternative way to rotate the model dynamically is by pressing down the wheel button on your mouse and then dragging the mouse around the screen.

Zoom: dynamically zoom the model by holding the left mouse button and dragging the mouse. Move the mouse up the screen to zoom in, or move the mouse down the screen to zoom out. An alternative way to zoom the model dynamically is by pressing down the <Shift> key and the wheel button on your mouse and then dragging the mouse up and down.

Rectangle Zoom: Draw a box to zoom in on a portion of the model. Drag the mouse from one corner to the opposite corner to define a box.

Pan: Dynamically pan the model by holding the left mouse button and dragging the mouse. An alternative way to pan the model dynamically is by pressing down the <Ctrl> key and the wheel button on your mouse and then dragging the mouse around the screen.

The commands in the Orientation pull-out menu will allow you to select the view displayed in the Preview area (top view, front view, enclose the view, and so on).

The Toolbars pull-out menu can be used to customize which toolbars are displayed.

Model Menu

The Parts, Heads, Mesh and Thickness commands provide access to dialog boxes that define the parameters used to create the pressure vessel. These menus are enabled only when creating a single nozzle vessel. See the page Creating a Pressure Vessel With a Single Nozzle for details.

The Preferences command provides access to the Preview Properties dialog box.

The Clipping Planes command provides access to the Clipping Planes Settings dialog box. You can define slice planes that hide the model on one side.

The Colors command provides access to the Color Selection dialog box. Clicking in any of the colored boxes brings up a menu with all of the available colors. You can select the color that you want to use for that specific item. To change the font used for the preview text, press the button next to Arial, 8 and choose a new font.

The Dialog Position menu can be used to specify the position at which you want the free floating input dialog boxes to be launched. Although each dialog box can be dragged to a different position on the screen, they reappear in the chosen location each time the dialog is re-opened.