Abstract
Lots of accident for industrial structures are caused by material fatigue. In some situations, detection of fatigue crack are required to prevent catastrophic accident. The stopping hole method is used as countermeasure for detected cracks. The stopping hole that is introduced in crack tip restrain stress concentration, and fatigue crack growth is delayed. However, stopping hole diameter is not determined based on knowledge of fracture mechanics. In many cases, the diameter is determined by engineer's experience. Measurement based on mechanical consideration is fundamental to enhance the efficacy of stopping hole. Some fatigue crack growth experiments with stopping hole is demonstrated in this study. Introduction of stopping hole into closed two cracks situation and out-plane compress stress effects for fatigue crack are discussed based on the experimental results. Number of loading cycle to cause re-growth of fatigue crack is derived by the experiments, and stress concentration factor is calculated by finite element method based on the experimental conditions.
