A modelling and simulation on failure prediction of ductile polymer based on craze evolution and annihilation

Ductile fracture of a polymer plate due to craze growth is characterized by a failure in the front of propagating neck. In this paper, the elastoviscoplastic constitutive equation, that explicitly represents the effect of craze, is rigorously derived. Through a thermodynamic discussion about arguments of craze rate function, a new craze evolution equation is proposed so as to express the craze concentration on the boundary between the oriented molecular region and the glassy one, and the craze annihilation in the oriented region, with a hydrostatic stress criterion of craze generation. Additionally, an evolution law of mean plastic strain affecting the craze growth is numerically identified for a polymer block with some circular holes. A finite element simulation is carried out in order to verify this model. The craze propagation and annihilation are visualized, and the possibility of failure prediction based on this model is also discussed.