HM-4615: Model Import, Airbags, Export Displayed, and Contacts with LS-DYNA

In this tutorial you will define the following: *AIRBAG_WANG_NEFSKE for the airbag mesh geometry; initial velocity of 3 mm/ms in the negative x-direction for the head with *INITIAL_VELOCITY_GENERATION; a contact between the airbag and head with *ICONTACT_AUTOMATIC_SURFACE_TO_SURFACE; *CONTACT_AIRBAG_SINGLE_SURFACE for the airbag; and a contact between the plate and the airbag with *CONTACT_NODES_TO_SURFACE.

Before you begin, copy airbag_start.key from <hm.zip>/interfaces/lsdyna/ to your working directory.
This tutorial will help you learn how to define LS-DYNA airbags, loads, and contacts using Engineering Solutions. The head and airbag are depicted in Figure 1.


Figure 1.

LS-DYNA Overview

In this section, you will learn how to import a LS-DYNA model, export displayed, and create and review contacts.

Import a LS-DYNA Model

Warning and Error Messages
When importing a LS-DYNA model, Engineering Solutions warning and error messages will be written to a file named dynkey.msg or dynaseq.msg, depending on the FE input translator being used. This file is created in the same folder from which Engineering Solutions was started.
Unsupported Cards
On import, the LS-DYNA cards not supported by Engineering Solutions are written to the unsupp_cards panel. Access this panel by clicking Setup > Create > Control Cards from the menu bar. Unsupported cards will be exported with the remaining model.
Care should be taken if an unsupported card points to an entity in Engineering Solutions. An example of this is when an unsupported material references a *PART. Engineering Solutions stores unsupported cards as text and does not consider pointers.
LSTC Dummy Files
You can read LSTC Hybrid III dummy files into Engineering Solutions by first converting the tree file to FTSS/ARUP tree file format.
Include Files
Engineering Solutions supports *INCLUDE. When Include files are imported into Engineering Solutions, the IDs of non-existing entities are maintained and will not be used for new entities. Use the Include files import option to specify whether to merge, preserve, or skip Include files on import. Access this option by clicking File > Import > Solver Deck from the menu bar.
Support of Include files:
  • The LS-DYNA keywords *INCLUDE, *INCLUDE_STAMPED_PART, *INCLUDE_STAMPED_PART_SET, *INCLUDE_TRANSFORM, and *INCLUDE_COMPENSATION_OPTION are mapped to Include files.
  • Switch to different types of Include files using the context menu Include File option in the Model Browser, with the exception of *INCLUDE_TRANSFORM, *INCLUDE_STAMPED_PART, and *INCLUDE_STAMPED_PART_SET.
  • Manage INCLUDE_TRANSFORM using the Transformation Manager.
  • During import, if the same Include file is referenced more than once using the *INCLUDE_TRANSFORM, then it will be imported, but appended with .#, where # = 1…n is shown in the Model Browser. These will not be exported unless you clear the Instance checkbox.
  • During import, *INCLUDE_STAMPED_PART and *INCLUDE_STAMPED_PART_SET are imported as "read only" by default to preserve the associativity.
  • During import, an Include file can be read when *INCLUDE comes after *INCLUDE_TRANSFORM.
  • When importing Include files, use Solver options in the Import browser to choose the type of Include file to import. This option enables you to set the Include file type to one of the following: INCLUDE, INCLUDE_STAMPED_PART, INCLUDE_STAMPED_PART_SET, or INCLUDE_COMPENSATION_options. This is the only option which enanables you to attach any file of type INCLUDE_STAMPED_PART or INCLUDE_STAMPED_PART_SET.

Export Displayed

From the Export - Solver Deck tab, select the Export Displayed option to export only displayed nodes and elements. Only model data associated to the displayed nodes and elements are exported. This model data includes materials and their associated curves, properties, portions of contacts, and output requests.

Create and Review Contacts

Table 1 describes how all secondary and main set types are created and specified in contacts.

Table 1.
Secondary and Main Set Type LS-DYNA card Panel Used to Create Card Equivalent type in Interfaces panel, add subpanel
EQ. 0: set segment id *SET_SEGMENT set_segment (contactsurfs) or … csurfs
    Interfaces, add subpanel entity
EQ. 1: shell element *SET_SHELL_Optio Entity Sets or… sets
set id n Interfaces, add subpanel subpanel entity
EQ. 2: part set id EQ. 2: part set id Entity Sets or… Interfaces, add subpanel split comps
EQ. 3: part id *PART Collectors comps
* EQ. 4: node set id *SET_NODE_Option Entity Sets or… sets
    Interfaces, add subpanel entity
* EQ. 5: include all   Interfaces, add subpanel all
* EQ. 6: part set id for exempted parts *SET_PART_LIST Interfaces, add subpanel and then card image subpanel sets
Add Subpanel
While the Interfaces panel, add subpanel has several main and secondary entity types to choose from in order to specify the LS-DYNA main or secondary set for a *CONTACT, only the valid main and secondary types are selectable for the particular contact you are creating.
When the main or secondary type is set to comps and only one component is selected, the LS-DYNA type is 3, part ID, and *PART is created. When multiple components are selected, the LS-DYNA type is 2, part set ID, and *SET_PART_LIST is created.
When the main or secondary type is set to sets, only those sets valid for the particular contact you are creating are selectable. For example, for *CONTACT_NODES_TO_SURFACE, only a list of node sets is available for secondary; you will not see a list of other set types, like element or part sets.
Review Contacts
Review contacts by clicking review in the Interfaces panel, add subpanel.

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.

Import the LS-DYNA Model

In this step, you will import the LS-DYNA model file into Engineering Solutions.

  1. From the menu bar, click File > Import > Solver Deck.
    The Import - Solver Deck tab opens.
  2. In the File field, open the airbag_start.key file.
  3. Click Import.
    The Import Process Messages dialog opens.
  4. Select Close to close the Import Process Messages dialog.

Define *AIRBAG_WANG_NEFSKE

In this step, you will define *AIRBAG_WANG_NEFSKE for the airbag mesh geometry.

  1. Create a set of parts, *SET_PART_LIST, containing the AirbagFront and AirbagRear components.
    1. In the Model Browser, right-click and select Create > Set from the context menu.


      Figure 2.
      A new set opens in the Entity Editor.
    2. For Name, enter airbag_set.
    3. Set card image to Part.
    4. For Entity IDs, click 0 Components > Components.


      Figure 3.
    5. In the Select Components dialog, select AirbagFront and AirbagRear and then click OK.


      Figure 4.
  2. Define the airbag (*AIRBAG_WANG_NEFSKE).
    1. Open the Solver Browser by clicking View > Browsers > Engineering Solutions > Solver from the menu bar.
    2. In the Solver Browser, right-click and select Create > *AIRBAG > *AIRBAG_WANG_NEFSKE from the context menu.


      Figure 5.
      A new control volume opens in the Entity Editor.
    3. For Name, enter airbag.
    4. Click SID.
      The entity selector becomes active.
    5. Set the entity selector to Sets as seen in Figure 6.


      Figure 6.
    6. Click Set.


      Figure 7.
    7. In the Select Set dialog, select airbag_set and then click OK.
      Note: The parts in this set define the airbag's geometry.


      Figure 8.
    8. For CV (Heat capacity at constant volume), enter 1023.0.
    9. For CP (Heat capacity at constant pressure), enter 1320.0.
    10. For T (Temperature of input gas), enter 780.0.
    11. Click LCMT (Load curve specifying input mass flow rate) > Curve.
    12. In the Select Curve dialog, select airbag LCMT curve and then click OK.
    13. For C23 (Vent orifice coefficient), enter 1.0.
    14. Click LCA23 (Load curve defining vent orifice area as a function of pressure) > Curve.
    15. In the Select Curve dialog, select airbag LCA23 curve and then click OK.
    16. For CP23 (Orifice coefficient for leakage), enter 1.0.
    17. For PE (Ambient pressure), enter 1.0E-4.
    18. For RO (Ambient density), enter 1.0E-9.
    19. For GC (Gravitational conversion constant), enter 1.0.
  3. Define an initial velocity of 3 mm/ms in the negative xdirection for the head with *INITIAL_VELOCITY_GENERATION.
    1. In the Solver Browser, right-click and select Create > *INITIAL > *INITIAL_VELOCITY_GENERATION from the context menu.


      Figure 9.
      A new load opens in the Entity Editor.
    2. Under Region Type, right-click on ID and select Create/Edit.
      The Create Sets dialog opens.
    3. For Entity IDs, click 0 Nodes > Nodes.
      Note: The Create Sets dialog will remain open for steps 3.d through 3.g. If necessary, move the Create Sets dialog to access the panel area.


      Figure 10.
    4. In the panel area, click nodes > by Collector.
    5. Select the Head checkbox as seen in Figure 11.


      Figure 11.
    6. Click select.
    7. Click proceed.
    8. In the Create Sets dialog, click Close.
    9. In the Solver Browser, *INITIAL folder, *INITIAL_VELOCITY_GENERATION subfolder, right-click on velocity and select Review from the context menu.
      Engineering Solutions highlights the load and greys out all of the other entities as seen in the following image.


      Figure 12.
    10. Right-click on velocity and select Review from the context menu.

Define a Contact Between the Airbag and the Head

In this section, you will define a contact between the airbag and the head with *CONTACT_AUTOMATIC_SURFACE_TO_SURFACE.

  1. Create a Engineering Solutions group with the card image SurfaceToSurface.
    1. In the Solver Browser, right-click and select Create > *CONTACT > *CONTACT_AUTOMATIC_SURFACE_TO_SURFACE > *CONTACT_AUTOMATIC_SURFACE_TO_SURFACE from the context menu.


      Figure 13.
      A new group opens in the Entity Editor.
    2. For Name, enter Airbag_Head.
  2. Specify the head to be the main surface with a surface type of 3, part ID.
    Tip: In this step, the Entity Editor should still be open for the Airbag_Head group.
    1. Click MSID.
    2. Set the entity selector to Components.
    3. Click Components.
    4. In the Select Components dialog, select Head and then click OK.
  3. Specify the airbag to be the secondary surface with a surface type of 2, part set ID.
    Tip: In this step, the Entity Editor should be open for the Airbag_Head group.
    1. Click SSID.
    2. Set the entity selector to Set.
    3. Click Set.
    4. In the Select Set dialog, select airbag_set and then click OK.
      Note: This set contains the components, AirbagFront and AirbagRear.
  4. View the main and secondary entities.
    Tip: In this step, the Airbag_Head group should be selected in the Solver Browser.
    1. In the Solver Browser, right-click on Airbag_Head and select Review from the context menu.
      The main and secondary entities temporarily display in blue and red. The other entities temporarily display grey.


      Figure 14.
    2. Right-click on Airbag_Head and select Review from the context menu.
      The entities return to their original display color.
  5. Define *CONTACT_AIRBAG_SINGLE_SURFACE for the airbag.
    1. In the Solver Browser, right-click and select Create > *CONTACT > *CONTACT_AIRBAG_SINGLE_SURFACE from the context menu.


      Figure 15.
      A new group opens in the Entity Editor.
    2. For Name, enter airbag.
  6. Define the airbag to be a secondary surface with a secondary set type of 2, part set ID.
    Tip: In this step, the Entity Editor should be open for the airbag group.
    1. Click SSID.
    2. Set the entity selector to Set.
    3. Click Set.
    4. In the Select Set dialog, select airbag_set and then click OK.
  7. View the secondary entities.
    Tip: In this step, the airbag group should be selected in the Solver Browser.
    1. In the Solver Browser, right-click on airbag and select Review from the context menu.
      The main and secondary entities temporarily display white and red. The other entities temporarily display grey.


      Figure 16.
    2. Right-click on airbag and select Review from the context menu.
      The entities return to their original display color.

Define a Contact Between the Plate and the Airbag

In this step, you will define a contact between the plate and the airbag with *CONTACT_NODES_TO_SURFACE.

  1. Define the AirbagRear component to be the main surface with a main type of 0, set segment ID.
    1. In the Solver Browser, right-click and select Create > *SET > *SET_SEGMENT > *SET_SEGMENT from the context menu.


      Figure 17.
      A new contactsurf opens in the Entity Editor.
    2. For Name, enter AirbagRear_main.
    3. Optional: Click the Color icon and select a color for the contactsurf.
    4. For Elements, click 0 Elements > Elements.
    5. In the panel area, set the second switch to elems as seen in Figure 18.


      Figure 18.
    6. Click elems > by collector.
    7. Select the AirbagRear checkbox.
    8. Click select.
    9. Click add.


      Figure 19.
  2. Reverse the contactsurf’s pyramids so they point out of the airbag.
    1. In the panel area, set the first switch to adjust contact direction as seen in Figure 20.


      Figure 20.
    2. Select the all elements checkbox.
    3. Click reverse.


      Figure 21.
    4. Click return.
  3. Create a *CONTACT_NODES_TO_SURFACE card.
    1. In the Solver Browser, right-click and select Create > *CONTACT > *CONTACT_NODES_TO_SURFACE > *CONTACT_NODES_TO_SURFACE from the context menu.


      Figure 22.
      A new group opens in the Entity Editor.
    2. For Name, enter Airbag_Plate.
  4. Specify the AirbagRear_main contactsurf for the contact’s main surface.
    Tip: In this step, the Entity Editor should be open for the Airbag_Plate group.
    1. Click MSID.
    2. Set the entity selector to Contactsurfs.
    3. Click Contactsurfs.
    4. In the Select Contactsurfs dialog, select AirbagRear_main and then click OK.
  5. Define the plate to be the contact’s secondary surface with a secondary type of 4, node set ID.
    1. For SSID, click 0 Nodes > Nodes.
    2. In the panel area, set the switch to nodes.
    3. Click nodes > by collector.
    4. Select the RigidPlate component.
    5. Click select as seen in Figure 23.


      Figure 23.
    6. Click add.
      Engineering Solutions adds the secondary selection to the group Airbag_Plate as seen in Figure 24.


      Figure 24.
    7. Click return.
  6. View the main and secondary entities.
    1. In the Solver Browser, *CONTACT folder, *CONTACT NODES TO SURFACE subfolder, right-click on Airbag_Plate and select Review from the context menu.
      The main and secondary entities temporarily display blue and red. The other entities temporarily display grey.


      Figure 25.
    2. Right-click on Airbag_Plate and select Review from the context menu.
      The entities return to their regular display color.

Review the Created Solver Entities

In this step, you will review the created solver entities using the Solver Browser.

  1. In the Solver Browser, *CONTACT folder, *CONTACT_AIRBAG_SINGLE_SURFACE subfolder, right-click on airbag and select Review from the context menu.
    Note: Only secondary (red) entities are shown because there are no main entities for this type of contact.
    The main and secondary entities temporarily display blue and red. The other entities temporarily display grey.


    Figure 26.
  2. Right-click on airbag and select Review from the context menu.
    The entities return to their regular display color.
  3. In the Solver Browser, *CONTACT folder, *CONTACT NODES TO SURFACE subfolder, right-click on Airbag_Plate and select Isolate Only from the context menu.
    Tip: If main and secondary entities are not visible, make sure the Show/Isolate/IsolateOnly/Attached checkbox is selected in the Options tab of the Browser Configuration dialog. Access the Browser Configuration dialog by right-clicking in the Model Browser and selecting Configure Browser from the context menu.
    Only the elements/components that are implicated in this contact display as seen in the following image.


    Figure 27.
  4. In the Solver Browser, *CONTACT folder, *CONTACT_AIRBAG_SINGLE_SURFACE subfolder, right-click on airbag and select Show from the context menu.
    The entire airbag displays as seen in the following image.


    Figure 28.

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.
    The Export - Solver Deck tab opens.
  2. Set Template to Keyword971.
  3. In the File field, navigate to your working directory and save the file as airbag_complete.key.
  4. Next to Export options, click .
  5. Set Export to All.
  6. Click Export.

Submit the Input File

In this step, you will submit the LS-DYNA input file to LS-DYNA 970.

  1. From the Start Menu, open the LS-DYNA Manager program.
  2. From the solvers menu, select Start LS-DYNA analysis.
  3. Load the airbag_complete.key file.
  4. Start the analysis by clicking OK.

View the Results

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

Save your work to a Engineering Solutions file.