Abstract
ABSTRACT: In most practical cases, the retardation of fatigue crack propagation has been observed after applying single overload. However, it was found that the fatigue crack growth rate actually accelerated after a tensile overload under a negative value of baseline stress ratio. This type of crack propagation behavior was related to the change of the compression residual stress to tensile residual stress distributed in the vicinity of the crack tip after an overload. In the present investigation, it was discussed that the number of delay and acceleration cycles of crack propagation were associated with a creating mechanism of static plastic zone, which influenced the residual stress state in front of the crack. In addition, the extent of fluctuation of the crack opening stress level related to the extent of the overload-affected zone. Also, it was found that the residual fatigue crack propagation life was influenced by the applied overload level and the conditions of applied cyclic stress after overloading.
