OS-SL-T: 1010 Brake Squeal Analysis

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

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

Application of boundary conditions and a finite element analysis of the problem are explained. Post-processing tools are used to determine unstable modes produced during braking.

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 Brake_Model.gda file you saved to your working directory from the Brake_Squeal.zip file.
  3. Click Open.
    The Brake_Model.gda database is loaded into SimLab. The .gda file only contains geometric data.

Create Solution

  1. From the Solutions ribbon, Physics group, click the Structural tool.
    The Create Solution dialog opens.
  2. In the Create Solution dialog, define the following options:
    1. For Name, enter Brake Squeal Analysis.
    2. For Solver, select OptiStruct.
    3. For Solution type, select Brake Squeal Analysis.
    4. For Select bodies, select all the bodies from the Assembly tab of the Model Browser and click OK.
      Figure 1. Solution Creation


In the Solutions tab of the Model Browser, an OptiStruct – Non 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 Apply.
    Figure 2. Back Plate Material Creation


    The Back plate material is created in the Property tab of the Model Browser.
  3. Create three more materials.
    1. In the Material dialog, enter the values as shown below and click Apply.
      Figure 3. Create Insulator Material


    2. In the Material dialog, enter the values as shown below and click Apply.
      Figure 4. Create Rotor Material


    3. In the Material dialog, enter the values as shown below and click OK.
      Figure 5. Create Pad Material


The created materials are displayed 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 6. Create Analysis Property


  3. In the Assembly tab of the Model Browser, select INNER-BACKPLATE and OUTER-BACKPLATE.
    Figure 7. Assign Property to Back Plate


  4. In the Analysis Property dialog, click Apply.
  5. Create an Insulators property.
    1. In the Analysis Property dialog, enter the values as shown below.
      Figure 8. Create Insulator Property


    2. In the Assembly tab of the Model Browser, select INSULATOR-INNER and INSULATOR-OUTER.
    3. In the Analysis Property dialog, click Apply.
  6. Create a Rotor property.
    1. In the Analysis Property dialog, enter the values as shown below.
      Figure 9. Create Rotor Property


    2. In the Assembly tab of the Model Browser, select ROTOR.
    3. In the Analysis Property dialog, click Apply.
  7. Create a Pad property.
    1. In the Analysis Property dialog, enter the values as shown below.
      Figure 10. Create Pad Property


    2. In the Assembly tab of the Model Browser, select INNER-PAD and OUTER-PAD.
    3. In the Analysis Property dialog, click Apply.
  8. In the Analysis Property dialog, click Cancel.
The created properties are displayed in the Property tab of the Model Browser.

Set Up Loads and Constraints

Create Local Coordinate

  1. From the Analysis ribbon, Loads and Constraints group, click the Coordinate tool.
  2. From the secondary tool set, select the Create tool.
    The Create Coordinate System dialog opens.
  3. In the Create Coordinate System dialog, enter the values as shown below.
    Figure 11. Create Cylindrical Coordinate


  4. In the modeling window, select the cylindrical face from the Rotor.
    Figure 12. Face Input for Cylindrical Coordinate Creation


  5. In the Create Coordinate System dialog, click OK.
A cylindrical coordinate is created at the center of the selected face. The coordinate is added in the Solutions tab of the Model Browser.

Create Contacts

Contacts are created between the Rotor and Pads to simulate the braking action of the pads against the rotor.

  1. From the Analysis ribbon, Loads and Constraints group, click the Contact tool.
    The Define Contact dialog opens.
  2. In the Define Contact dialog, enter the values as shown below.
    Figure 13. Create Contact


  3. In the Define Contact dialog, select the line edit field for Main faces.
    The line edit field is highlighted.
  4. In the modeling window, select the Rotor faces.
    Figure 14. Main Face Inputs for Contact Creation


  5. In the Define Contact dialog, select the line edit field for Secondary faces.
    The line edit field is highlighted.
  6. In the modeling window, select the Pad faces.
    Figure 15. Secondary Face Inputs for Contact Creation


  7. In the Define Contact dialog, select Create for the Friction coefficient table parameter.
    The Create Table dialog opens.
  8. In the Create Table dialog, enter the values as shown below and click OK.
    Figure 16. Define Friction Co-Efficient Table


    Tip: Press Enter within the table cells to add additional rows.
  9. In the Define Contact dialog, click OK.
The contact is created and added to the Solutions tab of the Model Browser.

Create Loadcase

  1. In the Solutions tab of the Model Browser, right-click the Brake Squeal Analysis solution and select Define using Load case from the context menu.
    A loadcase is created and added in the Solutions tab of the Model Browser.
  2. Right-click on LoadCase1, select Rename from the context menu, and enter Brake Pressure.
    The Loads and Constraints pertaining to simulate the braking action of the pads against the rotor are added in the Brake Pressure loadcase.
  3. Create a Disc Rotation loadcase.
    1. Right-click on LoadCase and selection Create Loadcase from the context menu.
    2. Right-click on the LoadCase2, select Rename from the context menu, and enter Disc Rotation.
  4. Create a Brake Squeal loadcase.
    1. Right-click on LoadCase and selection Create Loadcase from the context menu.
    2. Right-click on LoadCase3, select Rename from the context menu, and enter Brake Squeal.
    3. Right-click on Type and selectAnalysis Type > Brake Squeal Analysis.

Define Brake Pressure

  1. In the Solutions tab of the Model Browser, right-click the Brake Pressure loadcase and select Set Current from the context menu.
    The Brake Pressure loadcase is set to current. All newly created loads and constraints will be added to the current loadcase.
  2. From the Analysis ribbon, Loads and Constraints group, click the Loads tool.
  3. From the secondary tool set, select the Pressure tool.
    The Pressure dialog opens.
  4. In the Pressure dialog, enter the values as shown below.
    Figure 17. Define Brake Pressure


  5. In the modeling window, select the top faces of both Insulators.
    Figure 18. Face Inputs for Brake Pressure


  6. In the Pressure dialog, click OK.
The Brake Pressure is added to the current loadcase in the Solutions tab of the Model Browser.

Create Constraints

  1. From the Analysis ribbon, Loads and Constraints group, click the Constraints tool.
  2. From the secondary tool set, click the Fixed tool.
    The Fixed Constraint dialog opens.
  3. In the Fixed Constraint dialog, enter the values as shown below.
    Figure 19. Create Back Plate Constraint


  4. In the modeling window, select the side faces of both back plates.
    Figure 20. Face Input for Back Plate Constraint


  5. In the Fixed Constraint dialog, click Apply.
    The Back plate constraint is added to the current loadcase in the Solutions tab of the Model Browser.
  6. Create a Rotor Fixed constraint.
    1. In the Fixed Constraint dialog, enter the values as shown below.
      Figure 21. Create Rotor Fixed Constraint


    2. In the modeling window, select the faces at the Bolt holes of the Rotor.
      Figure 22. Face Input for Rotor Fixed Constraint


    3. In the Fixed Constraint dialog, click OK.
    The Rotor Fixed constraint is added to the current loadcase in the Solutions tab of the Model Browser.

Define Enforced Displacement

The enforced displacement is used to simulate the rotation of the rotor against the brake pads.

  1. In the Solutions tab of the Model Browser, right-click on the Disc Rotation loadcase and select Set Current from the context menu.
  2. Right-click on the Rotor Fixed constraint under the Brake Pressure loadcase and select Add to current Loadcase from the context menu.
    The Rotor Fixed constraint is added to the Disc Rotation loadcase.
  3. Right-click on the Brake Pressure constraint under the Brake Pressure loadcase and select Add to current Loadcase from the context menu.
  4. Right-click on the Back Plate constraint under the Brake Pressure loadcase and select Add to current Loadcase from the context menu.
  5. From the Analysis ribbon, Loads and Constraints group, click the Constraints tool.
  6. From the secondary tool set, click the Enforced tool.
    The Enforced Constraint dialog opens.
  7. In the Enforced Constraint dialog, enter the values as shown below.
    Figure 23. Create Enforced Constraint


  8. In the modeling window, select the cylindrical face at the center of the rotor.
    Figure 24. Face Input for Enforced Constraint


  9. In the Enforced Constraint dialog, click OK.
The Enforced Rotation is added to the Disc Rotation loadcase in the Solutions tab of the Model Browser.

Define Brake Squeal Loadcase

  1. In the Solutions tab of the Model Browser, right-click on the Brake Squeal loadcase and select Set Current from the context menu.
  2. Right-click on the Rotor Fixed constraint under the Disc Rotation loadcase and select Add to current Loadcase from the context menu.
  3. Right-click on the Back Plate constraint under the Disc Rotation loadcase and select Add to current Loadcase from the context menu.
  4. Right-click on the Brake Squeal loadcase and select Text Data from the context menu.
  5. In the Text Data dialog, enter DISPLACEMENT(UNSTABLE) = ALL and click Save.
    Figure 25. Enter Text Data


Define Loadcase Parameters and Output Requests

  1. In the Solutions tab of the Model Browser, right-click on the Brake Pressure loadcase and select Loadcase Parameters from the context menu.
    The Loadcase Parameters dialog opens.
  2. In the Loadcase Parameters dialog, enter the values as shown below and click OK.
    Figure 26. Create Loadcase Parameters for Brake Pressure Loadcase

  3. Right-click on the Brake Pressure loadcase, and select Result Request from the context menu.
    The Result Request dialog opens.
  4. In the Result Request dialog, enter the values as shown below and click OK.
    Figure 27. Create Output Requests for Brake Pressure Loadcase


  5. Create loadcase parameters and output requests for the Disc Rotation loadcase.
    1. Right-click on the Disc Rotation loadcase and select Loadcase Parameters from the context menu.
      The Loadcase Parameters dialog opens.
    2. In the Loadcase Parameters dialog, enter the values as shown below and click OK.
      Figure 28. Create Loadcase Parameters for Disc Roation Loadcase


    3. Right-click on the Disc Rotation loadcase, and select Result Request from the context menu.
      The Result Request dialog opens.
    4. In the Result Request dialog, enter the values as shown below and click OK.
      Figure 29. Create Output Requests for Disc Roation Loadcase


  6. Create loadcase parameters for the Brake Squeal loadcase.
    1. Right-click on the Brake Squeal loadcase and select Loadcase Parameters from the context menu.
      The Loadcase Parameters dialog opens.
    2. In the Loadcase Parameters dialog, enter the values as shown below and click OK.
      Figure 30. Create Loadcase Parameters for Brake Squeal Loadcase


The created loadcase parameters and output requests are added in the Solutions tab of the Model Browser.

Create Solution Parameters

  1. In the Solutions tab of the Model Browser, right-click on the Brake Squeal Analysis solution and select Solution Parameters from the context menu.
    The Solution Parameters dialog opens.
  2. In the Solution Parameters dialog, enter the values as shown below and click OK.
    Figure 31. Enter Solution Parameters Values


Solve and View Results

Solve the Solution

In the Solutions tab of the modeling window, right-click on Results 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. By default, the results data for the first loadcase will be displayed. Use the Results panel to change the loadcases, result component, and time steps.
Figure 32. Results Loading After Solving


Animate the results using the Animation toolbar at the bottom of the modeling window.
  1. In the Results panel, change the results loadcase from Brake Pressure to Disc Rotation.
    The stress developed due to the combined action of Disc roation and braking can be inferred.
  2. Change the results loadcase from Disc Rotation to Brake Squeal.
    In the Brake Squeal loadcase, three unstable modes (Mode 8, Mode 14, and Mode 22) are produced at frequencies of 1950.32 Hz, 3270.60 Hz, and 4776.90 Hz, respectively.
  3. Optional: From the Animation toolbar in the modeling window, select XYZ Deformation to visualize the mode shapes.