Material Calibration using Isight and Abaqus

Hello,

I am using Abaqus and Isight to determine the material coefficients of the
anisotropic Holzapfel hyperelastic model. My CAE model involves a
simulation of a biaxial test, where I intend to do material calibration
using experimental biaxial data.

I followed the example in the tutorial manual closely. However, when I run
Isight, the sum of squared difference and the relative error don't change
between the target and simulation results. The material parameters, even
though they are the variables, also don't vary.

Can you please help me?

Best regards,
Abdelrahman Sultan