Three-Dimensional FE Analysis Using Homogenization Method for Ductile Polymers Based on Molecular Chain Plasticity Model Considering Craze Evolution

Abstract

Thermoplastic polymers can be classified into glassy polymers and crystalline polymers depending on their internal structures. Glassy polymers have a random coil structure in which molecular chains are irregularly entangled. Crystalline polymers can be regarded as a mixture consisting of glassy and crystalline phases where molecular chains are regularly folded. Moreover, the fracture of ductile polymers occurs at the boundary between regions with oriented and non-oriented molecular chains after neck propagation. This behavior stems from the concentration of craze, which is a type of microscopic damage typically observed in polymers. In this study, three-dimensional FE simulations coupled with a craze evolution equation are carried out for glassy and crystalline polymers using a homogenization method and models of ductile polymers based on crystal plasticity theory. We attempt to numerically represent the propagation of a high-strain-rate shear band and a high-craze-density region in the macroscopic structure and to directly visualize the orientation of molecular chains in glassy and crystalline phases. In addition, differences between the deformation behavior of glassy and crystalline polymers at both the macroscopic and microscopic scales are investigated.