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Export quad8 elements to LS-DYNA

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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Altair Forum User

Hi Amit,

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

Will put up this as a request for enhancement.

QuyNguyenDai

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

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

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.

QuyNguyenDai

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

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.

QuyNguyenDai

Here's my test:

HM model:
LS-Dyna .k model:

Comparison between Hypermesh & LS-PrePost:

<?xml version="1.0" encoding="UTF-8"?>

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

QuyNguyenDai

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

LS-DYNA 2nd order elements in Hypermesh