Large Deformation Analysis for Glassy Polymer Based on Molecular Chain Plasticity Model Like Crystal Plasticity Theory Considering Change of Local Free Volume

Abstract

Polymers have desirable mechanical properties and have been widely used as structural materials instead of metals under severe mechanical conditions. In the previous paper, a new concept of “molecular chain slip system” is analogically proposed on the basis of crystal plasticity theory for metals. Moreover, an inelastic response law based on a probabilistic theory considering change of local free volume is adopted as a hardening law. However, the validity of this model is not numerically proved in detail. In this paper, we explain a method of large deformation analysis for glassy polymer using the present model. A finite element simulation is carried out for PMMA under plane strain tension. Macroscopic neck propagation with high strain rate shear band and directions of molecular chains in the oriented region are computationally visualized. It is indicated that independent rotation of slip systems can express an orientation hardening without constitutive equation of backstress. Furthermore, a nonlinear viscoelastic behavior that cannot be expressed by the conventional hardening law is accurately predicted