Investigation into three-dimensional effects of finite contact width on fretting fatigue

Three-dimensional effects due to finite contact width on the contact characteristics and fretting fatigue behavior were investigated. Two contact configurations were considered: cylinder-on-flat and flat with rounded edge-on flat. Three-dimensional finite element methodology was developed based on the submodeling technique. Stress components and relative displacement converged well with ease in both contact configurations; however, the flat pad configuration provided a slightly better and faster convergence. The contact region affected by the free edge boundary was dependent on the contact geometry, i.e. it was slightly more in the cylindrical pad than the flat pad, however the affected region was less than 7% of the total contact surface in the case of cylindrical-on-flat configuration. The contact pressure and stick region decreased at the free edge, which were in agreement with their experimental counterparts, hence a localized gross slip condition can develop near the free edge even though stick-slip condition prevails over most of the contact area. Analysis using a critical plane based multi-axial fatigue parameter showed that there is a very small effect due to free edge boundary on fretting fatigue crack initiation, which was confined near the edge. Two-dimensional plane strain analysis provided the contact characteristics and fretting fatigue behavior that were in agreement with their counterparts from three-dimensional analysis over most of the contact area. Therefore, two-dimensional plane strain methodology can be used for the analysis of fretting fatigue tests involving finite width.