A PARAMETRIC STUDY OF THE CRACK GROWTH BEHAVIOR OF HIGH DENSITY POLYETHYLENE BASED ON CRACK LAYER THEORY

摘要

Due to unique characteristics of the crack growth behavior of polymers, conventional fracture mechanics approaches on the crack growth have not been very successful. Crack Layer theory (CL) can be a good theoretical approach to model the sophisticated crack growth behavior of polymers. According to CL theory, polymers have different size and shape of process zone (PZ), and, especially, in the case of high density polyethylene (HDPE), a crack commonly propagates in a discontinuous manner under fatigue and creep loading conditions. In this paper, a parametric study was performed by a computer program based on CL theory for HDPE with two general types of test specimens, i.e. single edge notched tension (SENT) specimen and compact tension (CT) specimen. The effects of key parameters, i.e. the stress ratio (R-ratio) which is defined as the ratio of minimum and maximum stress of loading, specific fracture energy, and draw stress, on the crack growth behavior of HDPE were studied.