Abstract
The fatigue crack growth rate actually accelerated after a tensile overload under a negative value of baseline stress ratio R. This type of crack propagation behavior was related to tensile residual stress state distributed in the vicinity of the crack tip after an overload. In the present investigation, it was found that the delay and the acceleration extent of the crack propagation associated with the size of reversed plastic zone developing in the overload-affected zone when the crack tip penetrated in this zone under baseline stress ratio. Because knowing the variation of crack opening stress level is needed to evaluate a crack propagation rate under a variable loading, the prediction of the crack opening stress level using the values crack propagation rate, da/dN, was performed. Also, fatigue life after overload was evaluated.
