Generalized plane strain elements (eg CPE4G) with UMAT
Generalized plane strain elements (eg CPE4G) with UMAT
(OP)
I have a UMAT for the material behaviour that works with CPE4 elements but not with CPE4G elements.
I did mention the ref node and restrict DOF 4 & 5.
CPE4G works fine for elastic material or plastic ones given with the appropriate keywords, but NOT with a UMAT.
Does anyone know if I have to specify smthg in the UMAT so that it works for CPE4G elements?
Thanks
I did mention the ref node and restrict DOF 4 & 5.
CPE4G works fine for elastic material or plastic ones given with the appropriate keywords, but NOT with a UMAT.
Does anyone know if I have to specify smthg in the UMAT so that it works for CPE4G elements?
Thanks





RE: Generalized plane strain elements (eg CPE4G) with UMAT
RE: Generalized plane strain elements (eg CPE4G) with UMAT
...
AVERAGE FORCE 0.785 TIME AVG. FORCE 0.785
LARGEST RESIDUAL FORCE -1.12 AT NODE 4 DOF 2
LARGEST INCREMENT OF DISP. 1.000E-05 AT NODE 2 DOF 1
LARGEST CORRECTION TO DISP. -4.140E-06 AT NODE 1000 DOF 3
FORCE EQUILIBRIUM NOT ACHIEVED WITHIN TOLERANCE.
AVERAGE MOMENT 0.425 TIME AVG. MOMENT 0.425
ALL MOMENT RESIDUALS ARE ZERO
LARGEST INCREMENT OF ROTATION 4.248E-37 AT NODE 1000 DOF 4
LARGEST CORRECTION TO ROTATION 3.886E-52 AT NODE 1000 DOF 4
THE MOMENT EQUILIBRIUM EQUATIONS HAVE CONVERGED
***WARNING: THE SOLUTION APPEARS TO BE DIVERGING.
***ERROR: TIME INCREMENT REQUIRED IS LESS THAN MINIMUM SPECIFIED. ANALYSIS
ENDS
With CPE4, it works fine.
I don't know why it (yhe UMAT) works with CPE4 elements and not with CPEG4 elements!!!!!
RE: Generalized plane strain elements (eg CPE4G) with UMAT
For CPEG4 , I think, you should have NTENS=4 from which first 3 strain/stress components are the the direct stress/strain componets 11,22,33. And the 4th component should be the shear 12 component (for both stress and strains storage arrays)..i.e. (NDI=3,NSHR=1).
Anyhow , I do not know what your constitutive response described inside UMAT is , so I cannot speculate more...
but I would check the input data passed in by Abaqus for the two element types.
RE: Generalized plane strain elements (eg CPE4G) with UMAT
By removing this condition, it works fine for CPEG4 element.
Anyway, thanks for answering my question