“…Most of conventional approaches to fatigue have claimed that the fatigue crack is initiated at the maximum defect and grows up to final failure surface. For example, Murakami's square-root area parameter model (25) can predict the fatigue limit based on the maximum defect area and the Vickers hardness, and has been applied not only to steels but also to cast aluminium alloys (5), (10),(12)~(14), (16) . Most of the crack growth models (2),(4),(6),(7), (17), (19) to predict the fatigue life also start from the crack initiation at the maximum stress-raiser, that is, the maximum defect.…”