Mesh of a vault

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jlsp
Posts: 3
Joined: Wed Oct 14, 2020 7:58 am

Mesh of a vault

Postby jlsp » Wed Oct 14, 2020 9:24 am

Hello,
I’m new in GID and I’m modeling a vault (A quarter of a square modulus of a Jujol work) to analyze the isotropic damage, using GID + Opensees interface.
From what I've seen, I need to use hexahedral elements to analyze isotropic damage, but these elements do not allow me to mesh volumes with triangular or trapezoidal surfaces, which are what I have in the model.
Is there anything that can be done to fix this?
Thank you very much
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escolano
Posts: 1650
Joined: Thu Sep 18, 2014 3:31 pm

Re: Mesh of a vault

Postby escolano » Wed Oct 14, 2020 6:37 pm

Structured meshes of hexahedra are difficult to be created for a general shape (sometimes near impossible for complex shapes)

You must somehow manually divide your geometry volume in volumes of six faces (topologically bricks)
or at least in semi-structured volumes (a surface extruded in a direction), then and generate unstructured quadrilaterals on this top-bottom surfaces and a structured number of divisions in the extruding direction.

This is the power of unstructured tetrahedra/triangles, its capability to fit a complex shape.

If do you want attach a zip of your model and maybe I can provide you more specific advices
jlsp
Posts: 3
Joined: Wed Oct 14, 2020 7:58 am

Re: Mesh of a vault

Postby jlsp » Thu Oct 15, 2020 11:00 am

Thanks Escolano for your answer.
Attached a zip of the GID model.
I think this should be analyzed with shell elements, but for isotropic damage they are not available in GID + Opensees and in Kratos I don't know.
Attachments
volta_1.zip
(160.05 KiB) Downloaded 7 times
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escolano
Posts: 1650
Joined: Thu Sep 18, 2014 3:31 pm

Re: Mesh of a vault

Postby escolano » Fri Oct 16, 2020 6:43 pm

Your geometry was near to be semi-structured, all volumes are semi-structured (are a kind of extrusion: two opposite equivalent surfaces joined with lateral surfaces of 4-sides).
Only two volumes donesn't mach this pattern: I have modified these volumes (layer blue) and now all is semi-structured

Then can mesh it with hexahedra with
Mesh->Semi-structured->Volumes->Assign number of divisions in structured direction
and I have set 2 divisions and selected all volumes
then
Mesh->Element type->Hexahedra
and selected all volumes
and then generate a mesh with some size (e.g. 0.02 in my picture)

semi-structured-hexas.png
semi-structured-hexas.png (45.71 KiB) Viewed 318 times


I attach also my modified model:
volta_1_modified.gid.zip
(940.15 KiB) Downloaded 7 times


But take into account that in general won't be possible do it, only in this special case where the shape is like a shell.
jlsp
Posts: 3
Joined: Wed Oct 14, 2020 7:58 am

Re: Mesh of a vault

Postby jlsp » Mon Oct 19, 2020 5:59 pm

Great, I'll try to complete the analysis. Let's see if I get it
Thank you very much

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