Tutorial: Analyzing a Model with Contacts

Analyze a model with contacts to understand the difference between sliding and separating.

In this lesson you will learn how to:
  • Create a nut and bolt
  • Ground the bolt
  • Run an analysis
  • View contacts
  • Redefine the contact type


Open the Sway Bar Model

  1. Press F7 to open the Demo Browser.
  2. Double-click the Analysis_Contacts.stmod file to load it in the modeling window.
  3. Make sure the display units in the Unit System Selector are set to MPA (mm t N s).
    This will be important for comparing analysis results.
  4. Notice that the model already has a load case defined. Our objective for this load case is to accurately simulate the transfer of loads from the torque applied at the inside end of the bar to the bracket designated as the design space.


Create Nuts and Bolts in Aligned Holes

  1. On the Structure ribbon, select the Fasteners tool.
    Tip: To find and open a tool, press Ctrl+F. For more information, see Find and Search for Tools.
    The tool finds two locations with aligned holes.
  2. Click Apply on the guide bar to create fasteners.


  3. Observe as Inspire creates nuts and bolts in both locations.


Create a Nut and Bolt in a Single Hole

  1. While the Fasteners guide bar is still active, click Aligned Holes and select Single Holes.


  2. Inspire finds multiple locations with single holes. Click the single-hole location shown below to insert a grounded bolt.


  3. Right-click and mouse through the check mark to exit, or double-right-click.

Redefine the Contact

Redefine the contacts in the model before you run an analysis to permit or restrict their movement.

  1. On the Structure ribbon, select the Contacts tool.
    Tip: To find and open a tool, press Ctrl+F. For more information, see Find and Search for Tools.
    All of the contacts in this model are currently defined as bonded contacts (default) and are shown in blue.


  2. Left-click the contact where the bar touches the L bracket.
    A microdialog appears.


  3. Select the colored buttons on the microdialog to change the contact type.
    • Select Bonded if parts are bonded or glued together.
    • Select Sliding if there is relative sliding between the parts.
    • Select Separating if the relative parts can separate.
    • Select No Contact if parts are close but you don't want them to have contact.

Run the Analysis with Sliding

  1. While the Contacts guide bar is still active, left-click the contact where the bar touches the L bracket and select Sliding in the microdialog.
  2. Right-click and mouse through the check mark to exit, or double-right-click.
  3. On the Structure ribbon, click the Run OptiStruct Analysis button in the Analyze tool group.


  4. Run the analysis using the following settings.
    1. Change the Element Size to 3 mm.
    2. Set Speed/Accuracy to More accurate.
    3. Click Run.


  5. When the run is complete, select it in the Run Status window and click View Now to view the results.


  6. In the Analysis Explorer, select Factor of Safety from the Result Types dropdown.


  7. In the Analysis Explorer, click Show/Hide Deformed State to show the deformed state of the model. Click again to hide it.
  8. Notice that the L-bracket and the sway bar are acting as if they are attached, which is incorrect. There should not be local stress in the sway bar where it meets the L-bracket.


  9. Right-click and mouse through the check mark to exit, or double-right-click.
    Note: With Sliding contact types, you can run the model faster, but the results will not be as accurate.

Rerun the Analysis with Separating

  1. On the Structure ribbon, select the Contacts tool.
    Tip: To find and open a tool, press Ctrl+F. For more information, see Find and Search for Tools.
  2. Left-click the contact where the bar touches the L bracket and select Separating in the microdialog.
  3. Right-click and mouse through the check mark to exit, or double-right-click.
  4. On the Structure ribbon, click the Run OptiStruct Analysis button in the Analyze tool group.


  5. Run the analysis using the following settings.
    1. Change the Element Size to 3 mm.
    2. Set Speed/Accuracy to More accurate.
    3. Click Run.


  6. When the run is complete, select it in the Run Status window and click View Now to view the results.


  7. In the Analysis Explorer, select Factor of Safety from the Result Types dropdown.


  8. Notice that now the sway bar separates from the top of the L-bracket, as it would in real life.


  9. Right-click and mouse through the check mark to exit, or double-right-click.
Note: With Separating contact types, the model will run slower, but will better represent the actual physics.