Material Law 40 viscoelastic

Hello,

May anyone help me to discover material LAW 40 kelvin-Maxwell?

It is difficult to understand the constants their as there is no enough explanation in the manual for them.

Thanks

@Prakash Pagadala may you help? /emoticons/default_biggrin.png' srcset='/emoticons/biggrin@2x.png 2x' title=':D' width='20' />