Exercise 2: Define Boundary Conditions and Loads for the Seat Impact Analysis

In this exercise, you will define boundary conditions and load data for an LS-DYNA analysis of a vehicle seat impacting a rigid block.

This exercise will help you become familiar with defining LS-DYNA boundary conditions and loads using HyperMesh. The seat and block model are shown in Figure 1.

Figure 1.

Load the LS-DYNA User Profile

In this step, you will load the LS-DYNA user profile in Engineering Solutions.

  1. Start Engineering Solutions Desktop.
  2. In the User Profile dialog, set the user profile to LsDyna.

Retrieve the Engineering Solutions File

In this step, you will open the model file in Engineering Solutions.

  1. Open the model file by completing one of the following options:
    • Click File > Open > Model from the menu bar.
    • Click on the Standard toolbar.
  2. In the Open Model dialog, open the seat_2.hm file.
    The model appears in the graphics area.
  3. Observe the model using various visual options available in HyperMesh, such as rotation and zooming.

Define Gravity Acting in the Negative Z-Direction

In this step, you will define gravity acting in the negative z-direction with *LOAD_BODY_Z.

  1. In the Solver Browser, right-click and select Create > *LOAD > *LOAD_BODY (ACCELERATION) and select Option Z from the context menu.

    Figure 2.
    Engineering Solutions creates and opens a new load in the Entity Editor.
  2. Click LCID, and then click curve.

    Figure 3.
    The Select Curve dialog opens.
  3. In the Select Curve dialog, select gravity curve and then click OK.

    Figure 4.
  4. For SF (scale factor for acceleration in z-direction), enter 0.001.

Define the Seat Acceleration

In this step, you will define the seat acceleration with *BOUNDARY_PRESCRIBED_MOTION_NODE.

  1. In the Solver Browser, right-click and select Create *BOUNDARY *BOUNDARY_PRESCRIBED_MOTION (Accl) from the context menu.

    Figure 5.
    A new load collector is created and opened in the Entity Editor.
  2. Click TYPEID (Node Set ID) and then select accel_nodes.
  3. In the Export load on: field, change the option to NODES instead of SETS.
  4. In the DOF: field, select x-translation.
  5. Click LCID to select curve (motion value as time) acceleration curve.
  6. In the SF: field, type the load curve scale factor value of 0.001.

Export the Model

In this step, you will export the model to an LS-DYNA 971 formatted input file.

  1. From the menu bar, click File > Export > Solver Deck.
  2. In the Export - Solver Deck tab, set File type to Ls-Dyna.
  3. In the File field, navigate to your working directory and save the file as seat_complete.key.
  4. Click Export.

Submit the Input File

In this step, you will submit the LS-DYNA Input File to LS-DYNA 971.

  1. From the Start Menu on your desktop, open the LS-DYNA Manager program.
  2. From the solvers menu, select Start LS-DYNA analysis.
  3. Load the seat_complete.key file.
  4. Click OK to start the analysis.

View the Results in HyperView

In this step, you will view the results in HyperView.

Save your work as a Engineering Solutions file.