Fatigue crack propagation studies on a semi-elliptical surface crack in a plate subjected to bending loads

Semi-elliptical surface cracks subjected to cyclic bending loads are of importance to nuclear industry. In this study, the results of experimental studies on a SS316L(N) plate subjected to bending loads, at room temperature are presented. Plates with semi-elliptical surface cracks were experimentally subjected to cyclic bending loads. The crack profiles were monitored at regular intervals using a crack depth gauge. The crack profiles were used to characterize crack propagation laws along both surface and depth direction. The crack propagation profiles were simulated using available empirical equations and compared with the experimental results. The validity of the empirical equations for prediction of crack propagation was established. The experimental observations and empirical simulations indicate that the cracks tend to propagate more in the surface direction as compared to the depth direction, for the chosen loading and geometric conditions. The observed nature of crack propagation is significant for the design of the components for Leak Before Break (LBB).