562015-03-24 , 法政大学大学院理工学・工学研究科
As a result of torsional fatigue test with static combined tension-torsion loadings in smooth and notch specimen of medium-carbon steel, the more proportion of static tension increased, the more lifetime was reduced. On the other hand, the longest lifetime resulted from application of static torsion. The crack behavior was significantly different depending on the type of static combined loadings. The influence of static loadings on cracking was discussed quantitatively, divided into crack initiation, ModeⅡand ModeⅠ growth phases. It was found the effect of static loadings on the lifetime can be evaluated, employing an equivalent stress acting on the crack growth planes.