Shell elements of different order through thickness

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Alejandro Aguirre
Posts: 6
Joined: Thu May 05, 2022 1:15 pm

Shell elements of different order through thickness

Post by Alejandro Aguirre »

Hello

I'm currently working in a solid-shell element which creates 3D elements by extruding a 2D surface meshed by quadrilaterals or triangles, which results in hexahedra and prism elements.
As you know, hexahedra and prism elements result from the combination of line elements with quadrilaterals and triangles, respectively.

This extruding process allows to select independent interpolation orders for the quadrilateral/triangle part, set in GiD, and another order through the line, it ranges from linear to quintic.

According to the manual, we have these possible options:

Image

And I would need something like this (don't play attention to the numbering):

Image Image

So the top and bottom of the 3D element has the shape and order of the original 2D element, and the side walls have an arbitrary number of nodes.

Is there any way to postprocess this type of elements? So far I can only think of postprocessing them by dividing the element into many linear sub-elements so GiD can handle them.

Regards

Alejandro
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escolano
Posts: 1918
Joined: Sun Sep 05, 1982 10:51 pm

Re: Shell elements of different order through thickness

Post by escolano »

GiD elements in pre or post cannot have different polynomial degrees in different edges or directions, they are all linear (corner nodes), or all quadratic (mid-edge nodes also), and optionally quadratic9 with a extra center-face node also.

For postprocess purposes you can define a .post.msh file with a mesh different of the one of preprocess used for the calculation.

for triangular prisms you can use for postprocess a quadratic prism (12 nodes) and if your extrusion interpolation is only linear can set a result value interpolated linearly, although was not a variable of your system

for extrusion degrees greater than quadratic can do the suggested approach: define a mesh dividing your calculation elements in sub-elements of degree linear or quadratic.
Alejandro Aguirre
Posts: 6
Joined: Thu May 05, 2022 1:15 pm

Re: Shell elements of different order through thickness

Post by Alejandro Aguirre »

Thank you a lot!

Regards
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