ANALYSIS OF SLIDING BEHAVIOR FOR FRETTING LOADINGS - DETERMINATION OFTRANSITION CRITERIA

The determination of the sliding transition is of primary importance i n describing the loading conditions in a contact. Various damages have been observed depending on the sliding regime. Assuming Mindlin hypot heses, 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 fre tting behaviour. They present a theoretical constant at the transition but their experimental determination is dependent on the tangential a ccommodation 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 tr ansition through differential calculations. Finally an expression of t he boundary between the partial and gross slip is given to describe th e transition in fretting maps (RCFM). These theoretical results are co mpared with experiments obtained for two different tribe-systems HSS-C r-steel and HSS-TiN (5 mu m)-Cr-steel and various loading conditions. Good correlation is observed between theoretical and experimental resu lts if the tangential accommodation of the apparatus is taken into acc ount.