Consitutive model for polyrethane in high strain rate test
I have to model the behaviour of a polyurethane (Shore A 75) under high strain rate conditions in Ansys (Impact test). The model I chose was the hyperfoam because I read that this material behaves in a non-linear hyper viscoelastic way. My problem is that the Hyperfoam model requires 4 parameters (elastic stiffness for viscosity, initial viscous coefficient, powerlaw for the elastic stiffness, powerlaw for viscosity coefficient) but I dont know how to get it. I have got the Stress-Strain curve but I need to model the material in dynamic conditions and not static.
Is it Right to use the command TB, FOAM,,,,3 in this case?
How can I get the parameters I need?
I am afraid that you cannot get the necessary material parameters without more experimental test data. You may be able to approximate the parameters based on experience with polyurethane at high strain rates, but performing additional tests is the best way.