I'm modeling a material which its stress strain can be approximately bilinear so it has an certain Emodulus at the begining and then in the plastic region it has another E value.
I've tried to model it as classic metal plasticity. I then added the subroutine USDFLD to give those two values of E.
I feel confused now. When I'm modeling such a material am I supposed to use that subroutine to change the E or use a plasticity model? Actually I don't get the difference between the function of both. (Plastic material model and subroutine USDFLD)
Thanks a lot in advance,