Mechanics of polycarbonate in biaxial impact loading

Abstract

We investigate the deformation and failure behaviour of Polycarbonate(PC) under low-velocity biaxial impact loading. For this, we have conductedexperiments and numerical simulations of the falling weight impacttest (FWT) for different testing configurations. To model PC behaviour indynamic situations, we employed a 3D thermomechanical constitutive modelthat captures the strain rate, pressure and temperature dependence of deformationresponse. The finite element model also incorporates adiabaticheating and contact friction effects. Numerical predictions of the FWT forcedisplacementcurves are in good agreement with experimental observations.An assessment of the developed stress-strain fields indicates that the effectiveplastic stretch p is the invariant that most suitably represents the pointof material failure in all different test configurations. We examine the relationof a maximum p fracture criterion with existing criteria for PC onthe grounds of the triaxiality conditions specific to the biaxial impact test.Finally, we propose an extension of these criteria to enhance their capabilityof predicting failure in part geometries that may become subjected to morecomplex multiaxial loading scenarios.