Material parameters

[Karelin]

Hi all
I have a stress-strain curve from a uniaxial tensile-test. My material is orthotropic and I use an orhtotropic elasto-plastic material model with Hill-potential. How do I define the hardening in Abaqus, the plastic strains and yield-stress, by measuring in the curve.
I get the nominal stresses and strains from the curve. How do i express this in logarithmic strains and Cauchy stresses in an anisotropic case?

Thanks
Karelin