I am modelling Nylon (PA6 PLA) and am using Law 36 with Gruneisen EOS input also. When entering the C parameter in the EOS card, sound speed, using HyperMesh, the CE parameter in the Law 36 card, Young's modulus evolution constant, is automatically filled with the same value. I have to manually change this in my 0000.rad file prior to running after saving from HyperMesh. Just bringing this potential bug to developers' attention.