Thermal Effects (Combined) Analysis

Tutorial Level: Intermediate In this tutorial, you will evaluate squeak and rattle issues when exposed to thermal loading.

A typical challenge faced in the automotive industry is how does the vehicle interior perform under driving conditions while the vehicle has been parked in the sun for many hours.

To answer this question, vibration loads responses (Dynamics) need to be superposed to the temperature effect on parts (Thermal Expansion – Static), gaps are reduced for example. In this workflow, you will evaluate the squeak and rattle issues in a dynamic condition where the vehicle, in this case, parked under sunlight with a spike in internal temperature (Static loadcase). Later the car is driven, which is exposed to Dynamic Loading.
The objectives of this tutorial are:
  • Prepare the FE model for analyzing squeak and rattle issues.
  • Run analysis and post-process the results.

For this tutorial, you can use a new model and prepare the model analysis setup. Alternatively, you can download the starting files below.

To prepare the model analysis setup yourself, use a new model and prepare the model analysis setup. For this workflow, refer the following sections from the Detailed Risk and Root Cause Analysis tutorial: Import a model with Dynamic Event loadcase. For this workflow, you can use the model with solver deck created in the Detailed Risk and Root Cause Analysis usecase along with the Dynamic Loadcase. Choose the workflow according to your needs and refer to sections mentioned above for the procedures.

You will use the solver deck exported from the Detailed Risk and Root Cause Analysis usecase. Once you import the Dynamic Loadcase solver deck, you can proceed with Thermal (Static) Loadcase setup.

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

Import Model, DTS, and Material File

In this step, you will use the Import tool to import the required files.

  1. From the HyperMesh NVH menu bar, select Squeak and Rattle.
    The SnRPre and SnRPost ribbons open.
  2. From the SnRPre ribbon, select the Import tool.
    Figure 1.


    The Model Import dialog opens.
  3. Click , browse and select the tutorial_ip_snr_model.hm file.
  4. Click and specify the DTS File and Material File as tutorial_ip_snr_model_pre_output.csv and Tutorial_materialdb_snr.csv.
    Figure 2.


  5. Click Import.
    The selected model, DTS, and material file are imported to the session.
    Figure 3.

Define Thermal Loadcase

In this step, you will create a thermal loadcase.

  1. From the SnRPre ribbon, select the arrow next to the Dynamic Event tool and select Thermal Event.
    Figure 4.
    A guide bar opens.
  2. Select the nodes on the top surface of the IP Substrate and Dashboard Panel components.
    Figure 5.
  3. In the microdialog, enter 90 for the temperature value and click .
    The Thermal loadcase with the load collectors and other entities required for the simulation is created. Respective load collectors get created and are assigned to the loadstep.
    An SnRD dialog opens. You must verify the material properties needed for thermal anaysis are added in the material definition.
    Figure 6.
  4. Click OK.

Define Constraint

In this step, you will define model constraints.

  1. In the SnRPre ribbon, select the Constraints tool from the Thermal Event tool group.
    Figure 7.
    A guide bar opens.
  2. In the modeling window, select the node shown in Figure 8.
    Figure 8.
  3. In the microdialog, select SnRD_Static_Temp_1 for the Loadstep option.
  4. Click .
    The Static loadcase with the load collectors and other entities required for the simulation is created. Respective load collectors get created and are assigned to the loadstep.

Post Processing

In this step, you will perform a Full Analysis to understand the squeak and rattle risks in the model.

  1. From the SnRPost ribbon, select the Risk Assessment tool.
    Figure 9.


    The SnR Risk Assessment Browser opens.
  2. For Result File, select the dynamic result file tutorial_ip_snr_model.pch and the result containing thermal effects tutorial_ip_snr_model.h3d.
  3. Under Subcase Selection, select the static and dynamic loadcases.
    The rattle and squeak lines are segregated into separate tabs.
  4. For SEP, enter 0.
  5. Verify Full Analysis is selected to see the line-level plots and to continue to next steps of post-processing.
    Important: You must perform full analysis to access Sensitivity Analysis and combined loading capabilities.
    Note: If Full Analysis is not selected, only a summary analysis is generated. Full Analysis is selected by default.
    Figure 10.


  6. Click Plot.
    Note: Execution of the Full Analysis will take a considerable amount of time to chart histograms and plot contours based on the machine's performance.
    An execution success message opens.
    Figure 11.

Combined Loading

In this step, you will perform a Combined Loading study to understand the thermal effects on the squeak and rattle issues under Dynamic Loading condition.

  1. From the SnRPost ribbon, select the Combined Loading tool.
    Figure 12.


    The SnR Combined Loading Browser opens.
  2. For Loading Type 1, select the dynamic subcase.
  3. For Loading type 2, select the static subcase.
  4. Select the Affects gap check box.
    This selection ensures the gap and tolerance are influenced from the static analysis results.
  5. For E-Line(s) Selection, select All.
  6. Under Session Type, select Full Analysis to obtain detailed level results with updated Gap and Tolerance.


  7. Click Combine Results.
    The Combined Loading summary page is created.
    Figure 13.
    The combined effect on the selected interface is plotted in the results page. Considering line ID 70009 the result is as shown below:
    Figure 14.
    The following changes can be observed from the plots:
    • NewGap_Nominal_LC5_R2_Z and NewGap_Tolerance_LC5_R2_Z are introduced in the analysis. These are the changes in gap and tolerance due to thermal effects.
    • Due to the new Gap and Tolerance values, the relative displacement in the start of the interface is high compared to the results from dynamic analysis with actual Gap and Tolerance data.