The Application of Hyperelastic and Rate Dependent Models to the Multiaxial Deformation of Polymers

Abstract

The successful modelling of polymer forming processes requires at least partial knowledge of the material’s constitutive equation under the relevant conditions. The material behaviour can also give insight into events at the molecular level. These twin motivations have led us to study large deformations of a glassy polymer, in this case PVC, at temperatures near to its glass transition. In this regime theories based on finite elasticity are an essential tool. This remains true even where the material is rate-dependent, when the simple hyperelastic theory forms the basis of a more general model. We shall show that this approach has great predictive power when applied to multiaxial stretching of polymer sheets.