Modeling of viscolelastic material using MSC.MARC

Hi There,

sorry, I am new here, believe this is the right place to ask my question and not in blog posts.

I am trying to model thermal tempering of glass using the Narayanaswamy viscoelastic material model in MSC.MARC.

When I use shell elements (quad 4) the glass deforms due to the applied loads.

If I try to solve the same problem using solid elements (hex 8, 20) with the same material properties the glass doesn't deform anymore, and remains to be complete stiff.

Has anybody experienced the same problem with MSC. MARC or other packages?

Regards

Gerald