I am trying to simulate the metel deformation at elevated temperature. The constitutive model can be viscoplastic equation. The usual model used in literature is shown in the attached image. Some paper uses UMAT to implement it, also some paper usem CREEP subroutine to implement it. I am interested the second method. I am wondering how does this equation be implemented by CREEP subroutine. How to update the isotropic hardening stress R in CREEP. Any thoughts about this?
Thanks in advance.
