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Different calculation results, v.11.0.1 vs v.11.1.0

Valued Contributor
Valued Contributor

The computational scheme is an element that works only on stretching (red element).
The material properties of red element function set 13 .. Stress vs. Strain.

 

Shema.PNG

 

In nonlinear calculation (10..Nonlinear Static) to get the correct results v.11.0.1

 

02.PNG03.PNG

 

In nonlinear calculation (10..Nonlinear Static) in v.11.1.0 received incorrect results

 

04.PNG05.PNG

3 REPLIES

Re: Different calculation results, v.11.0.1 vs v.11.1.0

Siemens Phenom Siemens Phenom
Siemens Phenom
The difference in results is due to a change in the Nastran solver. V11.01 uses NXN 8.5 and V11.1 uses NXN 9.0
I will take a look into why the answers changed, might be a defualt change between versions. i will post my findings as soon as possible.

Re: Different calculation results, v.11.0.1 vs v.11.1.0

Siemens Phenom Siemens Phenom
Siemens Phenom

This change in result is due to a change in the NXN 9.0 solver. If you check the Nastran documentation, Basic Nonlinear Analysis User's Guide, under Elements for nonlinear analysis, you will find a table that shows nonlinear elastic material is not supported for CBEAM elements. I am not sure why a change was made in V9.0 to actually stop this behavior, but not issue a warning or error message.

 

The best workaround is to use a CROD element which does support nonlinear elastic material model.

Re: Different calculation results, v.11.0.1 vs v.11.1.0

Valued Contributor
Valued Contributor

fembrackin

Thank you for the solution of this problem.