Tutorial: Analyzing a Model with Contacts

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

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


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. Click the Structure tab on the ribbon and select the Fasteners tool.
    The tool finds two locations with aligned holes.


  2. Click Fasten All on the guide bar.


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


Create a Nut and Bolt in a Single Hole

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


  2. Inspire finds multiple locations with single holes. Click to apply a Grounded Bolt in the single hole location shown below.


  3. Right-click to exit the Fasteners tool.

Redefine the Contact

  1. Select the Contacts tool on the Structure ribbon.
    All of the contacts in this model are currently defined as bonded contacts and are shown in blue.


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


  3. Select the green button on the microdialog to change the contact type from bonded to contacting.


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

Run the Analysis with Sliding Only

  1. Click Run Analysis on the Analyze icon to open the Run Analysis window.


  2. Run the analysis using the settings shown below. Change the Element Size to 3 mm, set the Speed/Accuracy to More Accurate, and for Contacts make sure Sliding only is selected.
    This option is going to allow the parts to slide against each other, but prevent them from separating.


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


  4. In the Analysis Explorer, select Factor of Safety for the Result Type.


  5. Click the Show/Hide Deformed State icon on the Analysis Explorer.
  6. 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.


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

Rerun the Analysis with Sliding with Separation

  1. Click Run Analysis on the Analyze icon to open the Run Analysis window.


  2. Run the analysis again using the settings shown below.
    1. Under Contacts, select Sliding with separation. This option is going to allow the parts to slide against each other, and also separate.


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


  4. In the Analysis Explorer, select Factor of Safety for the Result Type.


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


  6. Right-click and mouse through the check mark to exit, or double-right-click.
Note: When using contacting parts, the Sliding only option allows you to run the model faster, but the results will not be as accurate. If you select the Sliding with separation option, the model will run slower, but will better represent the actual physics.