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

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.

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.

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_Z from the context menu.

   
   
   Figure 2.

   Engineering Solutions creates and opens a new load collector in the Entity Editor.
2. For Name, enter gravity.
3. Click LCID, and then click curve.

   
   
   Figure 3.

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

   
   
   Figure 4.

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

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

1. Create a load collector.
   1. In the Model Browser, right-click and select Create > Load Collector from the context menu.

      
      
      Figure 5.

      Engineering Solutions creates and opens a new load collector in the Entity Editor.
   2. For Name, enter accel.
   3. Set card image to <None>.
   4. Optional: Click the Color icon, and select a color for the load collector.
2. Create acceleration loads on nodes.
   1. Click BCs > Create > Accelerations from the menu bar.
      The Accelerations panel opens.
   2. Click load types =, and select PrcrbAcc_S.
   3. Click sets.
   4. Select the accel_nodes checkbox.
   5. Click select.
   6. Click the magnitude= switch, and select curve, vector.
   7. In the magnitude= field, enter 0.001.
      Note: This is the scale factor for the pre-defined curve to be specified in the next step for the acceleration loads. It will define the seat’s acceleration as a function of time.
   8. Set the orientation selector to x-axis.
      Note: This is the x-translational degree of freedom.
   9. Double-click curve.
   10. Select the acceleration curve curve.
   11. In the magnitude% = field, enter 1.0E+7.
       Note: This is the scale factor for the graphical representation of the acceleration loads. It does not affect the actual acceleration value.
   12. Click create.
       Engineering Solutions creates the acceleration loads.
   13. Click return.

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.

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.

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