Help needed!! in Abaqus
I have UMAT written to update stress and material tangent components for a user defined material model. I need stretch ratio as an input for my material model. For this I am using deformation gradient from UMAT. Problem is, when there is constant strain (strain rate = 0), for example when material stretched to 100% strain (rubber) and then held at that strain for certain time to see stress relaxation, the deformation gradient should give the same value of 100% strain, but to my surprise this is changing. Can any one help me with this.
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