OS-SL-T: 1020 Fatigue Analysis of a Universal Joint

Tutorial Level: Intermediate This tutorial demonstrates the creation of finite elements on a given CAD geometry of a universal joint.

Before you begin, copy the file(s) used in this tutorial to your working directory.

The application of boundary conditions and a finite element analysis of the problem is explained. Post-processing tools are used to determine the fatigue life of the joint due to static loading.

The following exercises are included:
  • Set up the problem in SimLab
  • Apply Loads and Boundary Conditions
  • Solve the job
  • View the results

Launch SimLab

Launch SimLab.

Import the Model

  1. From the menu bar, click File > Import > Database.
    An Import File dialog opens.
  2. Select the Universal_Joint.gda file you saved to your working directory from the Universal_Joint.zip file.
  3. Click Open.
    The Universal_Joint.zip database is loaded into SimLab. The .gda file only contains geometric data.

Create Solution

  1. From the Assembly tab of the Model Browser, select the Universal Joint and RBE bodies.
  2. From the Solutions ribbon, Physics group, click the Structural tool.
    The Create Solution dialog opens.
  3. In the Create Solution dialog, define the following options:
    1. For Name, enter Static Loading.
    2. For Solver, select OptiStruct.
    3. For Solution type, select Linear Static.
    4. Click OK.
    Figure 1. Create Solution


In the Solutions tab of the Model Browser, an OptiStruct – Linear Static solution with the selected bodies is created.

Create Materials and Properties

Create Material

  1. From the Analysis ribbon, Property group, click the Material tool.
    The Material dialog opens.
  2. In the Material dialog, enter the values as shown below and click OK.
    Figure 2. Fatigue Material Creation


    The Fatigue material is created in the Property tab of the Model Browser.

Create Property

  1. From the Analysis ribbon, Property group, click the Property tool.
    The Analysis Property dialog opens.
  2. In the Analysis Property dialog, enter the values as shown below.
    Figure 3. Create Analysis Property


  3. In the Assembly tab of the Model Browser, select Universal Joint.
  4. In the Analysis Property dialog, click Apply.
  5. Create a RBE property.
    1. In the Analysis Property dialog, enter the values as shown below.
      Figure 4. Create RBE Property


    2. In the Assembly tab of the Model Browser, select RBE.
    3. In the Analysis Property dialog, click OK.
The created properties are displayed in the Property tab of the Model Browser.

Set Up Loads and Constraints

Define Torque Load

  1. From the Analysis ribbon, Loads and Constraints group, click the Loads tool.
  2. From the secondary tool set, open the Force and Moment tool.
    The Force and Moment dialog opens.
  3. In the modeling window, right-click and select RBE Node from the context menu.
    Figure 5. Select RBE Main Node Selection Filter


  4. In the modeling window, select the RBE main node attached to the Universal joint.
    Figure 6. Select RBE Main Node


  5. In the Force and Moment dialog, enter the values as shown below and click OK.
    Figure 7. Torque Load Creation


The force Torque Load is added to the current solution in the Solutions tab of the Model Browser.

Define Constraints

  1. From the Analysis ribbon, Loads and Constraints group, click the Constraints tool.
  2. From the secondary tool set, select the Fixed tool.
    The Fixed Constraint dialog opens.
  3. In the Fixed Constraint dialog, enter the values as shown below.
    Figure 8. Create Fixed End Constraint


  4. In the modeling window, select the faces of the Universal Joint body.
    Figure 9. Face Input for Fixed End Constraint


  5. In the Fixed Constraint dialog, click OK.
The Fixed End constraint is added to the current Loadcase.

Define Fatigue Solution

  1. From the Solutions ribbon, Application group, click the Fatigue tool.
    The Fatigue dialog opens.
  2. In the Fatigue dialog, enter the values as shown below and click OK.
    Figure 10. Set Fatigue Solution Parameters


    The Fatigue Solution is created in the Solution tab of the Model Browser.
  3. From the Analysis ribbon, Loads group, click the Fatigue tool.
    The Fatigue Loading dialog opens.
  4. In the Fatigue Loading dialog, click Apply.
    Figure 11. Define Fatigue Loading


    The fatigue loading is defined.

Solve and View Results

Solve the Solution

  1. In the Solutions tab of the modeling window, right-click on Results under the Static Loading solution and select Update from the context menu.
    The Solution begins to solve.
  2. Right-click on Results under the Fatigue solution and select Update from the context menu.
    The solution begins to solve.
The results are automatically loaded back into the database.

Interpret the Results

The results are automatically loaded in the modeling window.

Figure 12. Result Example


  1. Use the Results panel to change the result component.
    Figure 13. Change Result Component


  2. In the Solutions tab of the Model Browser, right-click Results under the Static Loading solution and select Display from the context menu.
    Figure 14. Result Example


    The results for the Static Loading solution are displayed.