残留引張変形層の役割と疲労き裂伝播の下限界に関する一考察

概要

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Fatigue crack opening and closing phenomena are studied, considering a generation process of residual tensile layer close to the surface of a fatigue crack. As an absolutely necessary condition of fatigue crack propagation, generation of plastic hysteresis loop in the vicinity of and ahead of a crack tip is adopted. In other words, it is supposed that threshold phenomena of a fatigue crack propagation appears when no cyclic plastic work is done ahead of a crack tip during cyclic loading. As a result, it becomes clear that threshold values of ΔK and ΔK_<eff> are physical quantities which are not related to a fatigue crack stopping phenomena under various kinds of loadings except for constant amplitude loading. Moreover it can be considered that not only Paris's equation but also Paris-Elber's equation do not hold true under various amplitude loadings and holds true only under constant amplitude loadings.
社団法人日本船舶海洋工学会の論文
2003-03-20