Unveiling contribution of overload-induced residual stress to fatigue retardation pertinent to crack closure and stress intensity

Although residual stress (RS) and crack closure (CC) are generally accepted as predominant factors affecting postoverload fatigue crack growth (FCG), they cannot explain many peculiarities of FCG variation. Understanding overload mechanisms is essential to life prediction in variable amplitude fatigue load. In this study, the RS contribution behind and ahead of a crack tip and its relation to CC and stress intensity of fatigue cycling is clarified through combination of different stress ratios, heat treatment, overloads, and removals of crack wake and crack-tip plastic zone. Results indicate that overload-induced RS contribution is a single decisive factor for post-overload FCG rate without initial acceleration, and exhibits CC dependence behind crack tip and applied stress-intensity dependence ahead of crack tip.

Automated summary

This study clarifies the impact of overload on fatigue crack growth rate by enhancing the residual stress contribution behind and ahead of the crack tip and the relationship with crack closure effects. The results indicate that overload-induced residual stress contribution is a key factor in post-overload fatigue crack growth rate, exhibiting different mechanisms behind and ahead of the crack tip.