The strain-rate dependence of a commercial grade ABS copolymer has been analyzed in both compression and tension. By measuring in two loading geometries, the hydrostatic pressure-dependence on the material's deformation behavior can be established. An alternative method to determine pressure-dependence, based on the difference in strain-rate dependence for various loading geometries, has been presented. It was shown to be an effective technique, both for thermorheologically simple materials such as ABS, as well as thermorheologically complex materials, for example, PMMA. A yield criterion, based on an Eyring-type pressure-modified rate equation, has been compared to finite element simulations using the Eindhoven Glassy Polymer (EGP) constitutive model. Although both methods give quantitatively similar results for the yield stress prediction, only the fully 3D EGP model is able to represent the large-strain deformation behavior.
