Simulation of Crack Propagation in API 5L X52 Pressurized Pipes Using XFEM-Based Cohesive Segment Approach

Abstract

The cohesive zone model (CZM) is one of the most widely used damage models to describe the fracture processes of brittle and ductile materials, and has been usually combined with the conventional finite-element method (FEM). CZM in the context of the more effective extended finite-element method (XFEM) has recently been implemented in many applications, but it has not been widely used for crack propagation of pipelines. This paper aims to investigate the capability of the XFEM-based cohesive segment approach implemented in Abaqus to predict crack propagation of pipelines by calibrating a linearly decreasing traction–separation law with two damage parameters, the maximum principal stress and the fracture energy. The damage parameters for vintage pipeline steel (API 5L Grade X52) were systematically calibrated and verified by comparing the numerical results with eight full-scale experiments of pressurized and circumferentially surface-cracked pipe specimens. A correlation between the damage parameters and material yield strength and fracture toughness is discussed and an investigation of mesh size sensitivity included.