J-integral evaluation methods for cylinders with multiple circumferential cracks subjected to bending moments

Abstract

This paper describes the J-integral evaluation methods for the case of multiple circumferential cracks in a cylinder subjected to bending moments. J-integral is one of the parameters of fracture mechanics used in the fracture assessment of materials that show ductile fracture behavior. So far, there have been various J-integral evaluation methods proposed for a single crack in a cylinder, such as fully plastic solutions and a reference stress method, but none for multiple circumferential cracks. Therefore, this study examines the stress intensity factor evaluation method for cylinders with multiple circumferential cracks. This method estimates the stress intensity factor of multiple circumferential cracks in a cylinder based on a solution for single cracks. Next, a J-integral evaluation method based on the reference stress method is proposed. With this method, the reference stress is calculated from the plastic collapse strength of a cylinder with multiple cracks. The proposed methods have generality to the crack dimensions (sizes and positions) and the material characteristics of the cylinder, and were effective in predicting the J-integral simply and with high accuracy.

Keywords

• multiple cracks
• piping
• j-integral
• fracture evaluation
• fracture mechanics
• ductile fracture