DIRECT METHODS TO DETERMINE THE FRACTURE RESISTANCE CURVE FOR STEEL PIPES WITH CIRCUMFERENTIAL SURFACE CRACK

Abstract

The use of material J-R curve derived from through-thickness fracture specimens in the fracture mechanics based structural reliability analysis of critical components such as pipes, pressure vessels and large steel storage tanks leads to over conservative assessment of safe load and acceptable crack size. The transferability of the specimen or material J-R curve to the fracture resistance in a structural component thus represents the critical challenge in the structural integrity assessments. This thesis addresses the above issue by proposing two direct methods to measure the fracture resistance for surface-cracked pipes. The first procedure is an extension of the η-unloading compliance method commonly employed for standard through-thickness fracture specimen. The second method is a hybrid method based on the principles of multiple specimen method. The thesis also covers the effect of pipe reeling on the fracture resistance of pipes.