Hello everybody,
I've implemented a UMAT subroutine and I debugged it for one plastic increment. There is a problem that when one increment ends, and the stress and all state variables are saved for one increment, in the beginning of the next increment I expect that I have the same stresses and state variables while it is not the case (the most strange thing is that, after one plastic increment that my state variables are updated (which are not zero), for the next increment it sets all of them to be equal to zero). Can someone tell me what is the problem and how should I solve this problem?
regards,
Faezeh
Dear Faezeh Iranmanesh ,
can you upload the part of the code where you assign the new values of the stress, tangent stiffness and state variables?
Dear Eleftherios Tsivolas
At the end of each increment, I save the values of state variables, DDSDDE and stress and at the beginning of the next step Abaqus gives me some stress and state variables that should be equal to what I obtained in the last increment. I have attached the part that I update my state variables and DDSDDE and stress at the end of my code. Please find the attachment. I have also attached my state variables at the end of increment 69 and at the beginning of increment 70. As you see it cannot carry , state variables to the next increment, I don't know why.
I dont see anything wrong in the value assignment. Did you set in the material the correct number of state variables(*DEPVAR) in the section definition? This number let's Abaqus know the size of the state variables array. Also double check the ddsdde calculation that it is correct.
Yes, I set the DEPVAR as it is. I should check ddsdde.
Thanks, Eleftherios Tsivolas
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