炭素鋼予加工材の横穴よりの疲れき裂の挙動* -引圧疲れの場合-

概要

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Carbon-steel specimens which had been prestrained in tension and made a lateral hole in, were tested in the cyclic push-pun load to examine the effects of the prestrain ε and the diameter d of the lateral hole upon the fatigue strength, the fatigue crack propagation, the crack top opening etc. The main results obtained are as follows. 1) With δ＝const. .andεvarying in the order, 2，0，14％ and withε-＝const. and a varying in the order, 1.8，2.4，1.2，3.6，0mm，the endurance limit σ_w increased from the least at the tops. 2) In general the harder was the specimen, the higher was the endurance limit σ_w．At the failing cycle the hardness was higher in the order, ε＝2，0，14％, the lowest being at ε＝2％. 3） For every ε-＝const. Specimen, σ_w reached a minimum between the stress gradient χ＝1.8 and 2.5 mm^<−1> as in the case of the rotating bending fatigue. 4） The crack propagation formula obtained was dl/dN＝Cl, ie. the Frost and Dugdale type. 5）The crack opening can be evaluated using the non-opening ratio i as the crack top opening using the SIF ratio ΔΚ_<eff>/ΔΚ, it was revealed
北見工業大学の論文