Prepare for Analysis

Simplifying the model or part contributes to expediting the analysis. You can exclude parts whose purpose is simulated by a constraint and whose structural significance is otherwise small.

To help expedite analyses, you can suppress part features, such as rounds, that are either cosmetic or used to break sharp edges.

Exclude Components to Simplify Assemblies

Exclude a part or assembly from analysis:

1. Expand the assembly browser nodes to the level where you see the component to exclude.
2. Right-click the component and select Exclude From Simulation. Alternatively, right-click the component in the graphics region and click Exclude From Simulation.

The display of an excluded component changes to transparent while in the simulation environment.

Exclude Features to Simplify Parts and Assemblies

Suppressing features for analysis can speed up the meshing process. To exclude a part feature in the graphics window from your stress analysis:

1. Change the select filter to Select Features .
2. In the graphics window, select features to exclude, either individually or with multi-select.
3. Right-click and select Exclude From Simulation.

The features become invisible in the graphics window. In the browser, the features are unavailable and show with the Exclude icon . Dependent features are also made invisible and unavailable in the browser.

NoteThe excluded features are suppressed for your stress analysis, but the suppression is ignored when you return to the Part or Assembly modeling environment. Also, you cannot exclude features already suppressed in the modeling environment.

Alternatively, you can select features in the browser to exclude:

1. Expand the part browser node to the level where you see the features you want to exclude.
2. Right-click the feature and select Exclude From Simulation.

If there is an error while creating the finite element mesh, an error dialog box displays. The potentially problematic geometry object highlights, and the mesh creation stops.

Add a structural ( fixed, frictionless, or pin) constraint:

1. On the ribbon, click the constraint command for the type of constraint to add.
   NoteYou can also right-click the Constraints node in the browser and select the appropriate constraint type from the context menu.
2. In the dialog box, the select command is active, so you can immediately select the constraint location. Select the appropriate input for the constraint type. If you select more than one input, the selections must be of the same type: such as face, edge, or vertex. The input type is based on the constraint type.
   
3. Optionally, you can use the (More) command to expand the dialog box for access to other constraint parameters. The available parameters are based on the constraint type.
4. Click OK to add the constraint and close the dialog box. Alternatively, click Apply to add the constraint and keep the dialog box open.

You can edit or suppress constraints after you run the simulation, then rerun the simulation and see the effect of changing or suppressing the constraint.

Apply a fixed constraint with non-zero displacement

Loads are part of the boundary conditions you define for the simulation. There are various load types available to apply:

Access	Load Type	Inputs	Used to...
	Force	Faces, edges, and vertices. When selecting more than one input, all inputs must be the same entity type.	Apply a force of the specified magnitude to the selected faces, edges, or vertices. By default, Force is applied: Normal to the selected face. Parallel with the selected edge. Using the vector components in the expanded section of the dialog box.
	Pressure	Face	Apply a pressure of the specified magnitude to the selected faces. Pressure is uniform Applied Normal to the selected face.
	Bearing load	Cylindrical faces	Apply a load of the specified magnitude to the selected face. Forces are predominantly Radial (roller bearing) Perpendicular to axis (moment)
	Moment	Face Edges (shells only) When selecting more than one input, all inputs must be the same entity type.	Apply a load of the specified magnitude around the axis and perpendicular to the face.
	Body Loads	Linear: Face or edge Angular: Face or edge Location: Vertex	Apply linear acceleration or angular velocity and acceleration of the specified magnitude to the model. Linear Loads are applied perpendicular to the face with the magnitude value. Positive values are applied into the face. Loads are applied parallel to edge selections. Flip reverses directions. Angular Apply angular velocity and acceleration of the specified magnitude normal to a face or parallel to an edge. Flip reverses directions. Location Specifies an alternate location for the body loads. The location is shared between velocity and acceleration.
	Gravity	Face or Edge	Apply gravity of the specified magnitude normal to the selected face or parallel with the selected edge. Flip reverses gravity direction. Vector components define the magnitude and direction of gravity.
	Remote Force	Face	Apply a force of the specified magnitude to the selected face. By default, Force is applied: Normal to the selected face. Click Flip Direction to change directions. Use coordinates to specify the force location.

Apply a load:

1. In the Loads panel, click the load type to apply. The applicable load dialog box displays.
   NoteYou can also right-click the Loads node in the browser and select the appropriate load type from the context menu.
2. The selector command is active, and you can select inputs in the graphic region immediately. Based on the load type, make the corresponding selection.
3. The selection displays a glyph indicating the direction in which the load is applied. To change the load direction, use the vector components in the expanded section (for applicable load types) to describe the direction.
4. The More section of the dialog box also provides the glyph settings for that load. Adjust the glyph settings, if necessary.

Split faces for load application

In many applications, different locations on a component surface are subject to different loads. An example is a rotating shaft supported at both ends by bearings. The middle section of the shaft is under a moment, while the ends of the shaft see bearing loads

When you assign bearing loads to components, such as a shaft, you can split faces to create bearing contact locations.

Another example is the application of loads to simulate two individuals seated on a park bench. Split the top bench surface to create locations where you can apply the weight of the individuals.

Generally, materials are assigned at the Part model level in the components iProperties. There, the Physical Properties tab describes the fundamental aspects of the material. Stress analysis simulations use this information.

One aspect of analysis is to allow comparison of different materials for the design solution. Thus, in each simulation you are able to override the assigned material for a given part or assembly. The override occurs only for the specific simulation and does not affect the assembly model unless you promote changes to the model.

If an override material becomes inadequately defined for simulation purposes, the material node indicates an issue to resolve.

Override the assigned material:

1. Click Stress Analysis tab Material panel Assign to display a dialog box with components and their material assignments.
   NoteYou can also double-click the parent Material browser node or right-click the node and select Assign Materials.
2. In the Override Material column, click the cell that matches the component whose material you want to change. The row and associated component browser node and the component in the graphics window, highlight to reflect the selection.
3. Click the pull-down arrow to display the list of materials, and select the desired material. All occurrences of that component receive the material override. Thus, if you have 16 occurrences of a bolt, and override material for one bolt, the action results in overriding material for all 16 bolt occurrences.
   NoteYou can copy and paste material overrides. Right-click an Override Material cell and select copy. Then, right-click an Override Material cell and select paste.
4. Specify the material overrides for as many components as you want, then click OK to apply the material changes.

Show all material assignments

Work with multiple component materials

Delete a material override

Remove redundant overrides

Automatic contacts are detected during the simulation, without your taking direct action to detect them. If you want to see them before running the simulation or evaluate any that are detected, run the Automatic Contacts command.

To detect contacts, click Automatic Contacts in the Contacts panel.

The model is evaluated and contacts added. The faces must satisfy two criteria:

• The distance between the faces must not exceed the Tolerance value as expressed in the Simulation Properties.
• The angle between the faces must be within 15 degrees of being parallel.

When automatic contacts are generated, geometry decoration for mixed (solid + shell) and pure shell displays in browser indicating the type of contact. There are 3 possible types:

[E-E] Edge-Edge, contact created between two edges

[E-F] Edge-Face, contact created between an edge and a face

[F-F] Face-Face, contact created between two faces

Access to the Tolerance value and contact type is provided in the Simulation Properties on a per simulation basis. The angle requirement is fixed.

You can change the contact type by editing individual contacts or multi-select contacts and change the selection to another contact type.

When necessary, you can manually specify the contact types and components participating in the contact. You can specify the separation tolerance, but cannot change the 15 degree limit.

For example, use a Separation contact type in a weldment where:

• The components form a T shape.
• The vertical component contact face does not bond ideally.

All contacts are listed under the contact node in the browser. The type and participating components display next to the browser node name. Contacts are also listed in the browser as children of the components participating in the contact.

Add contact conditions manually between component faces:

1. First activate the Automatic Contacts command to gather all inferred contacts.
2. Activate the Manual Contact command.
   NoteYou can activate Manual Contact from the ribbon, or right-click the Contacts node in the browser and select Manual Contact from the context menu.
3. Select the first component or component face where contact occurs.
   NoteTo enhance selection capability, check the filter reference check box. Select the component first, and then specify the contact face.
4. Select the second component or component face where contact occurs. The selected components or faces are colored differently to distinguish the selection order.
5. Specify the contact type. You can specify the contact type before you select the inputs.

Contact type lists applicable contacts for the particular simulation type. Static analysis lists all contact types. Modal analysis lists only Bonded and Spring contact types.

Normal and Tangential Stiffness are values reserved and enabled only for spring contacts.

As you set up your simulation, changes you make to the model can require your attention. In such cases, the parent node of the affected child node displays the Update Required icon . Right-click the parent node and select the applicable Update command. The update is performed and the Warning icon displays next to the parent node when issues still exist. Expand the parent node to view the affected child node as indicated by the Warning icon.

For example, the following is a potential workflow associated with the stress analysis of a bracket assembly.

1. Create a simulation.
2. On the ribbon, click Stress Analysis tab Contacts panel Automatic Contacts
3. Click Manual Contact and add a minimum of one manual contact to the model.
4. Return to the Assembly environment and delete a component involved in a manual contact.
5. Enter the Stress Analysis environment. Note the presence of the Update Required icon next to the Contacts node. Expand all nodes under Contacts and view the Warning icons.
6. Right-click the Contacts node and select Update Automatic Contacts. The solver re-evaluates the interfaces and makes appropriate contact changes.

Since the component involved in the manual contact was deleted, the manual contact cannot be resolved. The Warning icon remains next to this manual contact and the Contacts node also shows a Warning icon.

In general, the Warning icon at the parent note indicates that at least one unsuppressed child node has a warning. If all child nodes with warnings are suppressed, the parent node is treated as healthy and no Warning icon displays.

When performing the analysis of parts and assemblies you can simplify you models containing thin bodies.

Prepare thin wall models for analysis:

1. Open a part or assembly file.
2. Click Stress Analysis on the Environments tab.
3. Create a new simulation.
4. On the Prepare panel:
   • Click Find Thin Bodies . Solid bodies that meet the thin component criteria are highlighted in the browser. To learn more about thin parts criteria, read the concept chapter above (Simplify the model section).
   • Click OK in the message box. Midsurface dialog box opens.
   • Click OK in the Midsurface dialog box to generate midsurface from selected solid body components.
   • Alternatively, click Offset to manually select faces to create thin shell components.
5. Add loads and constraints.

Important: Loads and Constraints applied to solid components become sick when converted to shell elements. We recommend applying them after you convert the model.

6. Solve the simulation, and view desired results.

How to convert parts back from shells to solids?

How to view midsurface or offset thickness?

How to delete multiple instances of midsurface or offset at once?

How to view multiple connectors of midsurface at once?

1. In Stress Analysis environment, create a new simulation.
2. On Prepare panel, click Offset .
3. Select a desired face.
4. In the Offset dialog box, specify the thickness. Distance is automatically calculated as half the thickness, and cannot be edited.
5. Click OK.

Use Midsurface command to generate midsurface from selected shell component. Only components that meet the shell criteria can be converted to midsurface. A message displays informing you when midsurface cannot be created.

1. In Stress Analysis environment, create a new simulation.
2. On Prepare panel, click Midsurface .
3. Select a body.
4. Click OK in the Midsurface dialog box.

We recommend using Find Thin Bodies command first. If any thin bodies are found, a message box displays. Click OK to open the Midsurface dialog box automatically.