CORRELATION OF FATIGUE-CRACK PROPAGATION IN POLYETHYLENE PIPE SPECIMENS OF DIFFERENT GEOMETRIES

Correlation in mechanisms and kinetics of step-wise fatigue crack prop agation in polyethylene pipe specimens of different geometries is stud ied experimentally. It is shown that crack propagation in a non-standa rd specimen cut from a real pipe and conserving the pipe geometry can be effectively simulated using a standard compact tension specimen, Go od correlation in both kinetics of step-wise crack propagation and fra ctography between the specimens is achieved if experimental conditions are chosen to assure equal values of (a) stress intensity factor and (b) stress intensity factor gradient at the initial notch tips. These results extend previous technique of fatigue accelerating slow crack g rowth used to predict lifetime of polyethylene pipes.