Modeling of axisymmetric slow crack growth of high-density polyethylene with circular notched bar specimen using crack layer theory

Because of the characteristic of high triaxial stress of a circular notched bar (CNB) specimen under tensile loads, it is a promising candidate for accelerated durability testing of high-density polyethylene (HDPE). To understand the slow crack growth (SCG) behavior of HDPE using a CNB specimen, it is practically important to base the evaluation of the SCG model using a CNB specimen on the concept of fracture mechanics. In this study, the SCG kinetics of HDPE with a CNB specimen is modeled on the basis of the concept of an axisymmetric crack layer (CL) system. CL theory is applied to the modeling of the axisymmetric SCG considering the geometry of the CNB specimen. Green's functions of the stress intensity factor and crack opening displacement of the CNB specimen are calculated in order to simulate the CL kinetics. The obtained Green's functions are also utilized to compute the thermodynamic forces for both the crack growth and the CL growth, and a generalized CL growth algorithm is developed. A parametric study of several key input parameters is conducted for validation of the developed CL model. In addition, actual SCG generated experimentally is simulated using the developed model, and it is found that the actual test results can be successfully simulated using the developed CL model.