Type of mesh for Elastic-Plastic analysis

[Alpete1430]

Hi all,
I'm trying to perform an Elastic-Plastic analysis to one of the systems which goes into Oil and Gas field.
It is governed by API 6A and ASME Sec VIII Div 2 'Design by analysis'.
My question is, which type of elements are good for this study and why?

Currently I'm performing an analysis with 2nd order Tet mesh and after some loading the elements are getting distorted.
So, if I mesh the system with 2nd order Hex mesh, will the results change?

What is the general practice across industry when it comes to what type of mesh to use in Elastic-Plastic analysis?

Thanks in advance.
Alpete1430

 

[karachun]

Try don’t use linear tet mesh. Both 2nd order tet and hexa are good. In general there is a rule of thumb - use at least 4 1st order elements per thickness.
Hexa look neat but not all geometry can be hexmeshed.
Ansys can dynamically remesh distorted elements.
Link
If you have any doubts - make two meshes with tet and hexa elements and compare results.

 

[Alpete1430]

Hi Karachun,
Thank you for the clarification.

 

[TGS4]

When performing an elastic-plastic analysis to VIII-2, you will need to demonstrate Protection Against Local Failure. When you do that, pay attention to the considerations noted in this paper

 

[Alpete1430]

Thank you TGS4.

I'll look into it.