Nanda Veralla
Ansys Employee

Hello Ammar,

Can you be more specific what you're trying to do? Do you want to fit 2 curves for a single material?

If you want to use curve fitting using APDL, you can follow the ANSYS help here for hyperelasticity

4.6. Hyperelasticity (ansys.com)

and here for Viscoelasticity

4.7. Viscoelasticity (ansys.com)

Prony series complex modulus is used in ANSYS to represent small-deformation harmonic viscoelasticity. For more details see this Viscoelasticity in the Structural Analysis Guide

Thanks and Regards,
Nanda.