What is the problem with my UMAT(my stress and state variables are not carried to the next increment correctly)?

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