Evaluation of fretting fatigue limit based on local stress at the contact edge

It was reported previously by the author that the effect of various factors influencing the fretting fatigue limit could be evaluated based on the local stress at the contact edge. In this report, the meaning of the local stress in fretting fatigue was studied. The two-step fatigue test showed that the value of the local stress fatigue limit was nearly the same as the fatigue limit of an edge cracked specimen containing a non-propagating crack formed by the pre-fretting fatigue. The change of stress intensity factor due to the crack growth under fretting fatigue condition was calculated by FEM. The fretting fatigue limit was the condition at which a micro-crack generated by fretting remains as a non-propagating crack. The condition to form a non-propagating crack in fretting fatigue was evaluated on the basis of the threshold condition of short fatigue crack growth.