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長谷川 邦夫*; Mare, V.*; 山口 義仁
Journal of Pressure Vessel Technology, 139(3), p.034501_1 - 034501_5, 2017/06
被引用回数:2 パーセンタイル:12.73(Engineering, Mechanical)Reference curves of fatigue crack growth rates for ferritic steels in air environment are provided by the ASME Code Section XI Appendix A. The fatigue crack growth rates under negative R ratio are given as da/dN vs. K. It is generally well known that the growth rates decreases with decreasing R ratios. However, the da/dN as a function of K are the same curves under R = 0, -1 and -2. In addition, the da/dN increases with decreasing R ratio for R-2. This paper converts from da/dN vs. K to da/dN vs. K, using crack closure U. It can be seen that the growth rate da/dN vs. K is better equation than da/dN vs. K from the view point of stress ratio R. Furthermore, extending crack closure U to R = -5, it can be explained that the da/dN decreases with decreasing R ratio in the range of -5 R 0. This tendency is consistent with the experimental data.