SIMULATION OF CRACK-TIP SUPERBLUNTING IN SEMICRYSTALLINE POLYMERS

A model for the elastic-viscoplastic flow of semi-crystalline polymers is presented. The deformation gradient is decomposed multiplicatively into elastic and plastic parts. The reference configuration for the p lastic response is chosen to coincide with the intermediate configurat ion on which the micromechanics texture evolution is defined. A macros copically averaged formulation of anisotropic plastic flow is derived from the microscopic description of texture proposed by Chen et al. (1 996). The derivation employs tensor function representation theory and the equivalence of plastic power between the macroscopic and microsco pic scales. Elasticity is included to describe the effect of elastic c onstraint on the development of the plastic zone. Small elastic strain is assumed. A finite element scheme is formulated within the present constitutive framework. The results of detailed numerical calculations are reported, and these results are believed to elucidate the phenome non of crack tip superblunting. The simulated results reconfirm the es sential features of crack tip superblunting and its rate dependency. ( C) 1998 Elsevier Science Ltd. All rights reserved.