疲労き裂進展下限界に及ぼす過大応力の影響

概要

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In order to investigate the effects of overload history on the behavior of crack growth threshold and the crack closure at the threshold, fatigue crack propagation tests under multi-overload and single overload of four different load patterns were carried out using 784 Mpa class high-tensile-strength steel bending specimens for the case of R=-1 and R=0. The results obtained were as follows; (1) For the multi-overload test, the grater the overload stress intensity K_<OL> was, the greater the threshold stress intensity k_<thv> was , both for the case of R=-1, and R-0. (2) As the result of single overload tests, in the case of R=0, the effect of the overload pattern appeared remarkably and the effect of the tension overload pattern was similar to that of multi-over- load. However, in the case of R=0, the effect mentioned above was little. (3) The fatigue crack growth threshold was expressible only by the effective threshold stress intensity range ΔK_<effth>, independent of the load history tested in this investigation.
社団法人日本材料学会の論文
1985-04-15