Export quad8 elements to LS-DYNA

Altair Forum User
Altair Forum User
Altair Employee
edited October 2020 in Community Q&A

For LS-DYNA user profile inHypermesh, there is no 'quad8' in 'elem types'. On exporting the mesh, elements are not exported and only the nodes are exported to the .k file. In 'HYPERMESH' user profile, 'quad8' is blank in 'elem types' and is not mapped to 'SHELL' as it should be. Does it mean that Hypermesh doesn't support quad8 mesh?

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited January 2018

    Hi Amit,

    As of now quadratic shell (quad8) element type is not supported in HyperMesh.

    Will put up this as a request for enhancement.

  • Q.Nguyen-Dai
    Q.Nguyen-Dai Altair Community Member
    edited January 2018

    For LS-DYNA user profile inHypermesh, there is no 'quad8' in 'elem types'. On exporting the mesh, elements are not exported and only the nodes are exported to the .k file. In 'HYPERMESH' user profile, 'quad8' is blank in 'elem types' and is not mapped to 'SHELL' as it should be. Does it mean that Hypermesh doesn't support quad8 mesh?

    Why need second ordre element for LS-DYNA? Are you sure?

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2018

    Why need second ordre element for LS-DYNA? Are you sure?

    I am solving wave propagation where 1st order element just doesn't work, however fine you mesh. But, LS-DYNA gives pretty good results with first order shell, probably it has incompatible modes activated by default. Moreover, it has a keyword that can internally increase the order to 2nd from a 1st order input mesh. I, on the other hand, use the mesh connectivity of LS-DYNA format into my own code. I had made my code compatible with LS-DYNA input deck and wanted to use Hypermesh to get quad8 mesh for complex shapes.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2018

    Hi Amit,

    As of now quadratic shell (quad8) element type is not supported in HyperMesh.

    Will put up this as a request for enhancement.

    It does mesh in quad8, just doesn't export it. Thanks anyways.

  • Q.Nguyen-Dai
    Q.Nguyen-Dai Altair Community Member
    edited February 2018
    • If you known the format of QUAD8 in LS-DYNA key
    • If the current LS-DYNA profile of HM can't export to QUAD8
    • So write yourself FE output template to get the mesh.
  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2018

    • If you known the format of QUAD8 in LS-DYNA key
    • If the current LS-DYNA profile of HM can't export to QUAD8
    • So write yourself FE output template to get the mesh.

    I haven't tried that yet. Can you provide any beginner's help material for writing output template for Hypermesh? Thanks.

  • Q.Nguyen-Dai
    Q.Nguyen-Dai Altair Community Member
    edited February 2018

    Here's my test:  

    • HM model: 
    • LS-Dyna .k model:  

    Comparison between Hypermesh & LS-PrePost:

    <?xml version="1.0" encoding="UTF-8"?>ls-dyna_shell-1.thumb.png.0c7138114197132bf66533905088ee64.png

     

    If you work already on customization of FE output, I'll send you my template.

    If not, I have to found a 'simple' way to show you how to do that.

     

     

     

    Unable to find an attachment - read this blog

  • Q.Nguyen-Dai
    Q.Nguyen-Dai Altair Community Member
    edited February 2018

    Here's a method to get 2nd order elements LS-DYNA from Hypermesh:

     

    LS-DYNA 2nd order elements in Hypermesh