Investigation of crack path near cold expanded hole

Abstract

In a structure, holes are concentrators of stresses. When the structure is subjected to a cyclic load, the holes should be carefully designed to prevent the occurrence of fatigue cracks. The now well-accepted technique of cold expanding holes mitigates the effect of stress concentration by introducing an area of compressive stress near the hole surface. The resulting compressive residual stress is balanced by an area of tensile stress, which is detrimental from a fatigue standpoint. In this study, we do not focus on the formation of fatigue cracks at the surface of the cold expanded hole, but investigate the path of the fatigue crack approaching a region with such a hole. Using a special algorithm to simulate fatigue crack growth, we show that the cold expanded hole attracts the growing crack. This insight sheds new light on the beneficial effects of cold expanded holes.