elastomer gasket life prediction using Fea

hi all i am doing Masters  my project is  Elastomer gasket life prediction using Fea.

my project objective is predict the service life of elastomer gasket in intake manifold of engine.

i am using the tool abaqus.its an visco hyperelastic approach. constitutive model consists of

  hyperelastic:  Ogden model

 viscoelstic :prony series

  in order to curve fit in prony series. i didnt know how?  inabaqus option is only for volumetric and shear test data. i didnt know how many hours i have to do stress relaxation test  to fit in prony curve? 

any body help me