HL-T: 1070 Transient Stress-Life (S-N)

Tutorial Level: Beginner

During Transient Fatigue Analysis, the load-time history input is not required, as it is calculated internally during transient analysis.

This example will detail a Stress-Life fatigue calculation for a transient subcase. Transient Fatigue Analysis is currently supported for SN (uniaxial and multiaxial), EN (uniaxial and multiaxial), and FOS calculations

In this tutorial you will:
  • Import a model to HyperLife
  • Select the SN module with a Transient Response loading type and define its required parameters
  • Create and assign a material
  • Create a transient event
  • Evaluate and view results
Before you begin, copy the file(s) used in this tutorial to your working directory.

Import the Model

  1. From the Home tools, Files tool group, click the Open Model tool.
    Figure 1.


  2. From the Load model and result dialog, browse and select HL-1070\Bracket-SN-Transient.h3d for the model file.
    The Load Result field is automatically populated. For this tutorial, the same file is used for both the model and the result.
  3. Click Apply.
    Figure 2.


Tip: Quickly import the model by dragging and dropping the .h3d file from a windows browser into the HyperLife modeling window.

Define the Fatigue Module

  1. Click the SN tool.
    The SN tool should be the default fatigue module selected. If it is not, click the arrow next to the fatigue module icon to display a list of available options.
    Figure 3.


    The SN dialog opens.
  2. Define the SN configuration parameters.
    1. Select Uni Axial as the method.
    2. Select MPa for the FE model units.
    3. Select Signed von for the stress combination.
    4. Enter a value of 0.6 for the certainty of survival.
    5. Select GOODMAN for the mean stress connection.
    6. Select Worst for the layer selection.
    7. Select Transient Response for the type of loading.
    Figure 4.


  3. Exit the dialog.

Assign Materials

  1. Click the Material tool.
    Figure 5.


    The Assign Material dialog opens.
  2. Activate the checkbox next to the part new_bracket.
  3. Create a new material.
    1. Click the My Material tab.
    2. Click to create a new material.
    3. Set the Elastic modulus to 200000.
    4. Change the Input method to Slope-intcept,2-seg.
    5. Set UTS to 2000.
    6. Set the Yield Strength to 1800.
    7. Set Poisson's Ratio to 0.333.
    8. In the SN tab, set the Fatigue strength coefficient or Curve intercept (SR1) to 1040.
    9. Set the First fatigue strength exponent or Slope (B1) to -0.231.
    10. Set the Cyclic limit of endurance or Transition point (NC1) to 600000.
    11. Set the Second fatigue strength exponent (B2) to -0.11.
    12. Set the Fatigue limit to 10.
    13. Set the Standard error value to 0.01.
    14. Click Plot & Save.
      Figure 6.


  4. Right-click on Mat_SN("n") and select Add to Assign Material List.
  5. Return to the Assign Material Data tab and select Mat_SN("n") from the Material drop-down menu for new_bracket.
    The Material list is populated with the materials selected from Material Database and My Material.
  6. Click under Finish. In the Surface Finish dialog, select POLISH from the drop-down menu then click OK.
  7. Click under Surf Treatment. In the Surface Treatment dialog, select NITRIDED from the drop-down menu then click OK.
  8. Set the Kf value to 1.3.
    Figure 7.


  9. Exit the dialog.

Create a Transient Event

  1. Click the Load Map tool.
    Figure 8.


    The Load Map dialog opens.

    By default, the Channel Type is set to Transient Response and can not be changed. Since this is a transient fatigue analysis, a load history is not required.

  2. Select Subcase 1 (transient).
  3. On the bottom half of the dialog, click to create an Event_1 header.
    Subcase 1 is listed under the event.
  4. Activate the Event_1 checkbox.
    Figure 9.


    Note: You can only select one transient subcase per event.
  5. Exit the dialog.

Evaluate and View Results

  1. From the Evaluate tool group, click the Run Analysis tool.
    Figure 10.


    The Evaluate dialog opens.
    Figure 11.


  2. Optional: Enter a name for the run.
  3. Click Run.
    Result files are saved to the home directory and the Run Status dialog opens.
  4. Once the run is complete, click View Current Results.
  5. Use the Results Explorer to visualize various types of results.
    Figure 12.


    Figure 13.