ANALYSIS OF SLIDING BEHAVIOR FOR FRETTING LOADINGS - DETERMINATION OF TRANSITION CRITERIA

The determination of the sliding transition is of primary importance in describing the loading conditions in a contact. Various damages have been observed depending on the sliding regime. Assuming Mindlin hypotheses, an analysis for an elastic ball on flat contact submitted to a constant normal force and a varying tangential force is made. Both the energy and the sliding ratio are studied in order to quantify the fretting behaviour. They present a theoretical constant at the transition but their experimental determination is dependent on the tangential accommodation of the testing apparatus. Nevertheless, by combining the two former variables it is possible to deduce a system free criterion. This analysis is completed by considering the discontinuity of the transition through differential calculations. Finally an expression of the boundary between the partial and gross slip is given to describe the transition in fretting maps (RCFM). These theoretical results are compared with experiments obtained for two different tribe-systems HSS-Cr-steel and HSS-TiN (5 mu m)-Cr-steel and various loading conditions. Good correlation is observed between theoretical and experimental results if the tangential accommodation of the apparatus is taken into account.