Mixed-mode I and II fatigue crack growth retardation due to overload: An experimental study

Environmental loads acting on structures usually cause fatigue crack propagation under variable amplitude mixed-mode conditions. In order to better estimate the remaining fatigue life, the fatigue crack growth behaviour under these conditions needs to be studied. In this paper, an experimental study where mixed-mode I and II overloads are applied to a fatigue crack propagating under mixed-mode I and II constant amplitude loading, is presented. The overloads are found to cause fatigue crack growth retardation, lasting over a length which is more than two times longer than the overload crack tip plastic zone extent estimated using a linear elastic solution.