Probabilistic fracture analysis of a straight pipe with through-wall circumferential crack using R6 method Original Research Article

Deterministic fracture analysis of cracked structures has been successful in demonstrating the behavior of structures under observed or postulated flaws. The key ingredients in a deterministic fracture mechanics analysis are the initial crack size, crack-driving force, applied stress and material properties. However, crack size, postulated accidental loading, mechanical and fracture parameters are often subjected to considerable scatter or uncertainty. Hence, the result of fracture mechanics analysis must be viewed with some skepticism. Quite often, conservative bounds on inputs are employed on these by providing a conservative estimate to fracture. However, it may lead to predict the overly conservative and unrealistic results. These uncertainties encourage us to adopt a statistical or probabilistic approach to the structural integrity. R6 is a well-known engineering assessment procedure for the evaluation of the structural integrity of the flawed structure. This paper presents the determination of failure probabilities of a straight pipe with a through-wall crack in the circumferential direction, using the R6 method. The pipe is subjected to an in-plane bending moment. The scatter in the crack size, mechanical and fracture properties are considered. The probability of failure is studied for variation in applied loads. Monte Carlo simulation is used to find the failure probability. The study is performed by constructing failure assessment diagram (FAD) using all the three options of R6. The results are compared with the approximate analytical formulations and with those available in the literature.