鋭い切欠部における微小疲労き裂成長の弾・塑性破壊力学的研究

概要

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Circumferentially grooved specimens were low cycle fatigued, and the local stress-strain relation was calculated at the notch root by FEM. The fatigue lives for crack initiation and final failure were satisfactorily evaluated by both the axial and equivalent plastic strain ranges produced at the notch root, and the Coffin-Manson law held for the notched specimen as well as for the smoothed specimen. The growth behavior of short surface crack at the notch root was examined in association with growth rates of the short surface crack in the smoothed specimen and of the long through-crack. The fatigue crack growth rates, da/dN, were successfully plotted against the cyclic J-integral range, ΔJ, and the strain intensity factor range ΔK_ε. The log da/dN vs. log ΔJ plots in the notched specimens were situated between those for the small surface crack in the smoothed specimen and for the long through-crack in the lower crack growth rate region, where the differences between each two were quite small to be allowable in a pratical sense, while these three da/dN vs. ΔJ relatives were nearly in accord with one another in the higher crack growth rate region.
一般社団法人日本機械学会の論文
1988-05-25