Dear all,
I have a problem with UMAT that could you give me some advice, please!
I test the subroutine with one element (C3D8 mesh size 3x3x3) and it gives an appropriate result with post-peak stress, strain.
However, when the element is divided into 36 elements (mesh size 0.5x0.5x0.5) the program cannot provide the result for a post-peak response. It shows "The selected primary variable is not available in the current frame for any elements in the current display group". It seems the program is terminated even though Abaqus still runs.
If you get any idea or experience with it, please give me some advice, please!
I appreciate your help,
Cheers,
Bac
Hi Bac,
This message is typical when one or more variable in your UMAT diverge. Try looking at the values of your variables directly into you code introducing some write statements expecially for stresses and for the tangent operator (stress, ddsdde). If one of them diverges you can start looking at the first term that diverges with the same debugging procedure.
Dear Federico,
Thank you for your suggestion.
I will try with it.
But I still wonder that why the problem happens when using more elements?
Cheers,
Bac
The one element test is almost not affected by tangent operator problems why the 36 elements test is more. Maybe your problem is in a not perfect extimation of the ddsdde term... Try to check it and verify it in a monoaxial strain condition.
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