疲労表面き裂の形状表現式について

概要

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A project of three years experimental researches on fatigue crack growth from multiple planar surface flaws has been made since 1976, accumulating a lot of data on the changing characteristics of surface fatigue crack shape during growth. On the basis of the data about 99 fatigue cracks, which were obtained from the researches, a statistical analysis was made in order to make a modification of the empirical expressions of surface fatigue crack shape, that were previously proposed by kawahara-Kurihara-Iida. It was found that the expressions themselves are essentially applicable for the estimation of b/a versus b/t relation, where b, a and t are crack depth, half crack length on surface and plate thickness respectively. Also found is that the constants in the expressions deduced from the present analysis gave a better estimation than the previous ones, within the range of ±20 percent of error percentage in estimation of b/a for over than 90 percent of data. In addition, a simple formula for expression of a fatigue crack shape during growth was newly proposed, showing comparable order of accuracy in estimation.
社団法人日本船舶海洋工学会の論文