How to calculate the material parameters for hyperfoam material model

[YixiangZhang]

I don't understand the part in chapter 19.5.2 Hyperelastic behaviour in elastomeric foams in Abaqus Analysis User's Manual vol 3. In the section called Determining the hyperfoam material parameters, it says you can specify test data and allow Abacus to calculate the material parameters. When i'm inputing the simple shear test sub option, it asks for Nominal stress, Nominal Strain and Nominal transverse stress. Based on the nominal stress calculation formula in the manual on page 134, it needs material parameters to calculate the nominal stress.

My question is if you want the material parameters to be defined by material test, how could you have material parameters in the formula for Nominal stress which is part of the test data input abaqus ask for.

Cheers,
Adam