Hi All,

 I would like to use Abaqus to model the viscoelastic material  behaviour of a polymer.

I have material data from a simple uniaxial creep experiment (nominal strain vs time).  I tried to use the viscoelastic material model in Abaqus.  I am a bit confused as to how I need to enter my data (what format). 

The manual says I have to specify the normalized bulk and normalized shear compliance . 

I've started to look into the modeling of polyurethane.  So far I'v found one paper that specifically looks into how to model the mechanical behavior of PU. It describes a possible constitutive model for PU:

Stress-strain behavior of thermoplastic polyurethanes, Qi,H.J.; Boyce, M.C., Mech. Mater. 2005, 37, 8, 817-839

Does someone know of any other resources on the modeling of PU?  Thanks, Andreas