Estimation of Energy Release Rates and Instability Analysis for a Pipe With a Circumferential Surface Crack Subjected to Bending

Abstract

An estimation of the energy release rate J for a three-dimensional nonlinear elastic solid containing a two-dimensional plane crack is presented. Special attention is focused on a pipe with a circumferential surface crack subjected to bending. The present analysis gives an estimation of the distribution of J along the crack front of a circumferential surface crack. Fracture instability of the cracked solid is also discussed. Based on the deformation theory of plasticity and a postulated criterion for crack growth, wall-breakthrough instability of the circumferential surface crack is examined. The predictions of the present analysis are in agreement with experimental observations, and indicate that a longer circumferential surface flaw is more susceptible to radial instability. Implications of this study on “leak before break” conditions are also discussed.