[施業・測定研究室]B.林業機械に関する研究 : 集運材用半調整式架空船集材について

Ⅰ.はじめに Ⅱ.理論値 Ⅲ.測定条件 Ⅳ.結

[経営測定研究室]B.林業機械に関する研究 : 集運材用半調整式架空線について

Ⅰ.はじめに Ⅱ.主索および曳索の張力につい

炭素鋼の腐食疲労における累積損傷に関する研究

In order to investigate the effect of cyclic stress history on corrosion fatigue strength, two-step fatigue tests were performed on the 0.45%C carbon steel smooth specimens in rotary bending in laboratory air and in salt water (3.0% NaCl). It was clarified that the values of the cumulative ratio changed complexly under various conditions, involving the magnitude of stresses, stress sequences and environments. It was pointed out from the experimental examination that the behaviour of the maximum crack length on the specimen surface is useful for evaluation of fatigue damage. The maximum crack length during fatigue was deduced by using the statistics of extremes and approximating the distribution of crack lengths by three-parameter Weibull distribution. The cumulative damage rule for two-step fatigue was introduced theoretically by regarding fatigue damage as the maximum crack length obtained from the statistical properties of distributed cracks on the smooth specimen surface