2008 Volume 2 Issue 2 Pages 243-253
It is well known that a single tensile overload applied during constant stress amplitude cycling at a positive stress ratio causes crack growth retardation. In the case of a negative stress ratio, however, the fatigue crack growth rate actually accelerated after a tensile overload. This crack growth behavior is related to the residual stress distribution and crack closure behavior. Therefore, the crack propagation rate before and after applying an overload can be evaluated by the effective stress intensity factor range. Where crack propagation was accelerated after applying an overload, blunted crack tips which occurred because of overload worked as sharp notch roots. The shape of the crack tip affected crack growth after overload in the case of negative stress ratio. In this study, it is found that acceleration of crack growth after overload is dependent on the crack opening behavior and loading conditions after overload.
