Hyperelasticity and Solver

Hello,

My model is currently using one material as a hyperelastic material and the other as a linear elastic material in an air-bound box. However, in reality, both materials within the box are elastomers(rubbers) that follow a hyperelastic behavior. I cannot get my solver to converge on a solution when applying the hyperelastic model to the other rubber but it works fine with just one hyperelastic material and one linear material. Is this a solver issue or am I doing something wrong with the hyperelastic material?


Note that the hyperelastic model I am using is Arruda-Boyce and the values I have used are ballpark estimates until they are determined.

Thanks,
Rob