What is the problem with my UMAT(my stress and state variables are not carried to the next increment correctly)?
It is difficult to say what is causing the problem. I recommend that you check that you allocate enough space for your state variables in the Abaqus inp-file using the *DEPVAR command. Besides that, I also recommend that you continue to print out the state of your UMAT variables. That may help you understand where the problem comes from.