Influence of Variable Loading on Very High Cycles Fretting Fatigue

Abstract

Fretting fatigue has lower fatigue strength than that for smooth specimen, and it is thought that fretting fatigue has no fatigue limit. However, there is little knowledge of the influence of variable loading on very high cycle fretting fatigue because very high cycle fatigue tests using a conventional fatigue testing machine are impractically time consuming. In this study, very high cycle fretting fatigue tests under repeated two-step variable amplitude loading were conducted by using an ultrasonic fatigue testing machine for the sake of accelerating fretting fatigue testing. The applicability of the modified Minor's rule was discussed, and it would seem to show that stress amplitudes lower than fretting fatigue strength at 108 cycles does not contribute to the fatigue life.