Thank you very much for your hints. I am more familiar with ANSYS but I have used it just for modeling not for programing. As I have understood well for both of them I have to use Fortran? The theory that has to be programed is already difficult so I want to make a good choice for the program...
I have to implement a new constitutive relation in a commercial FE code. Can somebody help me with the tips: which of them (Abaqur or Ansys) is better and easier for programing?