An investigation on fretting fatigue mechanism under complex cyclic loading conditions

•We investigated the fretting fatigue mechanism under complex cyclic loading conditions which were common and highly influence the fretting fatigue behavior. However, it is barely studied at present.•A methodology was proposed and an experimental configuration was designed to investigate the fretting fatigue mechanism under complex cyclic loading conditions.•The cyclic normal load will enlarge the slip region of the contact interfaces, making the crack nucleation location moves toward the middle range of the contact region.•At the same mean normal load series, the fretting fatigue life will decrease as the increasing of the normal load amplitude level. The fatigue life will decreases as the increasing of the mean normal load level at the same normal load amplitude series.•It can be demonstrated that the complex cyclic loads have a positive effect on fretting damage, making the fatigue life shorter than those in constant normal load conditions.

In this paper, a methodology was proposed and an experimental configuration was designed to investigate the fretting fatigue mechanism under complex cyclic loading condition. This condition is common and highly influences the fretting fatigue behavior. However, it is barely studied at present. A series of fretting fatigue tests shown that cyclic normal load will enlarge the slip region of contact interfaces, making the crack nucleation location moves toward the middle range of contact region. It is demonstrated that complex cyclic loads have a positive effect of fretting damage, making the fatigue life shorter than those in constant normal loading conditions.