Probabilistic Assessment of Creep-Fatigue Crack Propagation in Austenitic Stainless Steel Cracked Plates

Abstract

This study investigates the effects of uncertainties in the prediction of creep-fatigue crack propagation in 316L(N) austenitic stainless steel plates containing a semi-elliptical surface defect. Different parameters in geometry, material behavior and test condition are considered as random variables in probabilistic assessments. Monte-Carlo sampling method is employed to estimate the probability distribution of desired outputs, i.e.such as propagated crack sizes, stress intensity factors and creep rupture life. It is shown that, generally, the uncertainty in prediction of crack sizes in both trough-wall direction and along the surface of the plate will be increased by increasing the time (crack size). Furthermore, probabilistic evaluations are performed using different reliability methods to calculate the probabilities of exceedance of available experimental results. These evaluations clarified the importance of consideration of uncertainties in creep-fatigue crack growth prediction. Sensitivity analysis, are carried out to provide useful information about the order of importance of random variables. It is found that, initial crack size may be an important random variable in such probabilistic assessments.