On modeling of slow crack growth in polyethylene

A crack and a domain of crazed material ahead of the crack (process zone), commonly observed in polyethylene, are considered as a thermodynamic system called the crack layer. According to the crack layer theory, slow crack growth in polyethylene is largely a result of degradation of the process zone material. In the present work, a simplified version of the theory is employed to model discontinuous slow crack growth often observed in polyethylene. The proposed model predicts the relation between the rate of crack growth and the stress intensity factor consistent with that obtained experimentally for the steady stage of fracture process. Lifetime evaluation is discussed.