Hi everyone,

I am using ABAQUS CAE fit uniaxial stress/strain curves to a hyperelastic model. I've found that my material is best described using a reduced polynomial model. I now want to reproduce the stress/strain curves using the model parameters in MATLAB. While I was able to find the formula for the strain energy density of reduced polynomial models in the ABAQUS documentation, I did not find any derivations for stress/strain curves based on the strain energy. 

Can anyone tell me the correct approach to get those formulas? 

Thank you very much!