A non-uniform friction distribution model for partial slip fretting contact

In partial slip fretting contact, the coefficient of friction (CoF) is often assumed to be constant along the contact surface. The literature shows that the CoF is related to the relative slip, which varies in the slip region of a partial slip contact. This study develops a methodology to consider the effects of non-uniform CoF distribution in the slip region. Two cases were investigated. In the first case, the axial stress on the substrate (specimen) was absent, while the axial stress was present in the second case. In both cases, the CoF was assumed to be static, kept constant in the stick zone, and varied linearly in the slip region. A closed form solution was developed to determine the stick/slip region size and the equivalent constant CoF for the no-axial stress case, and it was supplemented with finite element analysis. In the second case, where an axial stress was applied on the specimen, the stick/slip region size and the equivalent constant CoF were determined by finite element analysis. The equivalent constant CoF with an axial stress was slightly greater than that without the axial stress due to the larger slip zone size. The stress state in the contact region based on the equivalent constant CoF was comparable to its counterpart from the linearly varying CoF case.