Simulation of Ductile Crack Propagation for Pipe Structures Using X-FEM

Conventional finite element method is continually used for the flaw evaluation of pipe structures to investigate the fitness-for-service for power plant components, however, it is generally time consuming to make a model of specific crack configuration. The consideration of a propagating surface crack is further accentuated since the crack propagation behavior along the crack front is implicitly affected by the distribution of the crack driving force along the crack front. The authors developed a system to conduct crack propagation analysis by use of the three-dimensional elastic-plastic extended finite element method. It was applied to simulate ductile crack propagation of circumferentially surface cracks in pipe structures and could realize the simultaneous calculation of the J-integral and the consequent ductile crack propagation. Both the crack extension and the possible change of crack shape were evaluated by the developed system.