Rolling effect in fretting fatigue test at the crack initiation stage

The aim of this work is to perform a detailed analysis the cracks paths obtained in fretting fatigue tests with cylindrical contact but taking into account presence an unavoidable (due device’s stiffness) small oscillatory rolling. In order obtain crack surfaces were measured confocal microscope after tests. Besides, area and surface initiation location by means optical microscope. measurements indicate that substantially larger than theoretical one according Hertz´s theory, contrary done only static normal load, which both experimental areas match perfectly. This observation means, that, due pad’s geometry (cylindrical) stiffness test setup, rolling occurring during when tangential loading developed. To reproduce phenomenon, 2D FEM model Stress/strain fields along cycle are analysed, noticing substantial change hot-spot point stress distribution, compared non-rolling case. predict initial path, previously developed model, based on critical plane parameter, applied using stress/strain results. results show better prediction orientation estimation, case, considering as reference via