高サイクル域における衝撃荷重下での疲労強度および疲労き裂進展に及ぼす負荷時間の効果

概要

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In the previous study, the authors had developed a Hopkinson bar-type highspeed impact fatigue testing machine, and carried out impact fatigue tests on two sorts of carbon steels. In this study, after some modifications and improvements of the testing machine, a new method was introduced to generate impact stress patterns with various loading times at maximum stress levels, and impact fatigue tests were carried out on SIOC(0.1%C) steel by changing the loading time from 470 to 940μs Fatigue crack growth tests were also carried out on the same material using another Hopkinson bar-type testing machine, with the loading times of 780 and 1050μs. It was confirmed that the impact S-N property in the high cycle range was dependent on the loading time and there was a relationship σ_<max> (N_fT)^m=D,whereσ_<max> is maximum stress, N_f the number of cycles to failure, T the loading time, and m and D are constants. It was also confirmed that the fatigue crack growth rate was affected by the loading time and N_fT (the product of the number of cycles and the loading time) was an important parameter governing the crack growth rate.
一般社団法人日本機械学会の論文
1989-04-25