Mr. Zhang,
Your post has bee very informative. However after trying tho implement them, Abaqus throws an error at me.
What I did is calculate the F33 by imposing the Sigma33 = 0 constraint and calculate F33 iteratively from this equation (non-linear root finding method). Then I used this F33 for finding the stress value returned to Abaqus.
For the material Jacobian, first I determined the 6x6 matrix first and reduce it to the 3x3 matrix by substituting for D3 in Tau1, Tau2 and Tau4 expressions and taking the coefficients of the D1, D2 and D3 as the components of the 3x3 material jacobian matrix.
(here F represents the deformation gradient, Tau represents the variation in Kirchoff Stress and D represents the rate of deformation)
However when I use this UMAT with the CPS8R element, Abaqus throws up the following error:
"ERROR in job messaging system: Error in connection to analysis.
Error in job 2D-CPS8R-TrialUMAT: Abaqus/Standard Analysis exited with an error - Please see the message file for possible error messages if the file exists. Job 2D-CPS8R-TrialUMAT aborted due to errors."
For debugging the UMAT I have opened a "debug.log" file in the UMAT and have given write out of variables to this debug log file. However I cannot find the debug.log file in the job directory which might mean that Abaqus is not reading the UMAT file. I have already checked the link with Fortran compiler. The "Data Check" completes successfully but on submitting the job the above error shows up.
Could you please give any pointers on what I am doing wrong?
I would have attached the UMAT and inp but could not find how!
Mr. Zhang,
Your post has bee very informative. However after trying tho implement them, Abaqus throws an error at me.
What I did is calculate the F33 by imposing the Sigma33 = 0 constraint and calculate F33 iteratively from this equation (non-linear root finding method). Then I used this F33 for finding the stress value returned to Abaqus.
For the material Jacobian, first I determined the 6x6 matrix first and reduce it to the 3x3 matrix by substituting for D3 in Tau1, Tau2 and Tau4 expressions and taking the coefficients of the D1, D2 and D3 as the components of the 3x3 material jacobian matrix.
(here F represents the deformation gradient, Tau represents the variation in Kirchoff Stress and D represents the rate of deformation)
However when I use this UMAT with the CPS8R element, Abaqus throws up the following error:
"ERROR in job messaging system: Error in connection to analysis.
Error in job 2D-CPS8R-TrialUMAT: Abaqus/Standard Analysis exited with an error - Please see the message file for possible error messages if the file exists. Job 2D-CPS8R-TrialUMAT aborted due to errors."
For debugging the UMAT I have opened a "debug.log" file in the UMAT and have given write out of variables to this debug log file. However I cannot find the debug.log file in the job directory which might mean that Abaqus is not reading the UMAT file. I have already checked the link with Fortran compiler. The "Data Check" completes successfully but on submitting the job the above error shows up.
Could you please give any pointers on what I am doing wrong?
I would have attached the UMAT and inp but could not find how!