過大予荷重効果によるき裂状微小欠陥を有する鋼の疲労下限界応力拡大係数範囲の向上(<小特集>M&M2009材料力学カンファレンス)

抄録

Bending fatigue tests were carried out on the steel specimens containing an artificial small slit which simulated small surface crack in order to investigate the effects of overload on the threshold stress intensity factor range (ΔK_<th>). Tensile overload was applied to the specimens containing a semi-circular slit with depth of 0.1, 0.3 and 0.5mm. Then, bending fatigue tests were conducted on the specimens with a stress ratio R=0.1. The fatigue limits and ΔK_<th> of specimens containing a semi-circular slit were increased by the tensile overload effects. However, increasing of the fatigue limits and ΔK_<th> were saturated if the applied tensile stress reached the yield point of the material.