Hi,

I am trying to implement an anisotropic material model in Abaqus using UANISOHYPER_INV user subroutine. My model strain energy includes both stretches and strain invariants (e.g. Ogden material model + invariant terms). My problem is that stretches are not passed in UANISOHYPER_INV and only invariants are passed in this subroutine as information. How can I have the stretch values in this subroutine? Even if I can access the strain values I can calculate the stretches.

Thanks.