A REVIEW OF FRACTURE MECHANICS MODELS OF TUBULAR JOINTS

Fracture mechanics methods are used to assess the significance of cracking in any structure, but a tubular joint is very complex to analyse. However the improvements in numerical methods, such as stress analysis using finite elements, and extensive full-scale laboratory testing (UKOSRP, ECSC, etc.) have allowed various workers to propose fracture mechanics models of tubular joints. This paper presents a critical review and comparison of these models. It concludes that simple plate models can provide upper and lower bound stress intensity factor solutions for cracked tubular joints. Stress intensity factors from three dimensional finite element analysis of a tubular joint are in reasonable agreement with semi-empirical data. However, in the absence of a validated database the paper concludes that any analytical assessment of a crack in a joint should be viewed as tentative.