A Plastic Fracture Mechanics Prediction of Fracture Instability in a Circumferentially Cracked Pipe in Bending—Part I: J-Integral Analysis

Abstract

A method of evaluating the J-integral for a circumferentially cracked pipe in bending is proposed. The method allows a J-resistance curve to be evaluated directly from the load-displacement record obtained in a pipe fracture experiment. This method also permits an analysis for fracture instability in a circumferential crack growth using a J-resistance curve and the tearing modulus parameter. The influence of the system compliance on fracture instability is discussed in conjunction with the latter application. The results suggest that a compliant piping system containing a crack can exhibit ductile fracture instability after some stable crack growth. The importance of using a J-resistance curve that is consistent with the type of constraint for a given application is emphasized.