Location of the first yield point and wear mechanism in torsional fretting

Material wear in the contact area may lead to fatigue failure of a structural component under torsional fretting. It is necessary to investigate the wear mechanisms accompanying torsional fretting, especially during the unloading process. This paper intends to analyze the torsional stress field during loading and unloading processes and to explore the link between fretting wear and the location of material first yield, for which a parametric study on factors influencing this location, such as coefficient of friction and stick zone ratio, is committed. Because the surface shear traction is complex during the unloading process, the subsurface stress field is calculated by means of an efficient semi-analytical method. The relationship between the first yield location and wear mechanism is examined through observations of worn surfaces from a set of torsional fretting experiments.