Influence of various material parameters on void growth in amorphous glassy polymers

Abstract

Glassy polymers were developed in the 1950s and in the present era, they are used in various applications. Over the past decades, their usage has increased considerably and thus there is a need to capture their behaviour in various conditions to extend their applications in diverse new domains. However, the implementation of lack of accurate material models in commercial FEA software has limited the research work in this area. Like ductile metals, glassy polymers also follow the three stages of failure: void nucleation, void growth, and coalescence. The current study aims to solve this problem with the help of a user subroutine in ABAQUS. VUMAT subroutine in ABAQUS explicit software is written based on the existing theories, which are validated from experimental data collected from earlier literature. Successful implementation of the subroutine is followed by studying the influence of different material parameters and loading rate on the material response. Furthermore, void growth study is done with cell model geometry, where one percent void is considered. Two materials chosen for the study are polycarbonate (PC) and polymethyl methacrylate (PMMA). Void growth rate is studied with various strain ratios. Softening and hardening parameters in material models are also varied to do a comparative void growth rate study. It has been observed that the void growth is also affected by the loading rate. The initial void is also varied to see the effects of its size over the void growth phenomena.