A Global Methodology to Quantify Fretting Damages

Fretting wear and fretting fatigue are commonly associated with damage of quasistatic loaded assemblies and with decrease in lifetime. Depending on the sliding condition, wear induced by fretting or cracking induced by fretting can be observed. To quantify such competitive damage phenomena, a fretting map approach has been extensively applied describing the sliding conditions and the damage evolution as a function of the normal force and the displacement amplitude. This approach, considered as a useful methodology to analyze tribo-systems, nevertheless presents the limitation of not allowing a direct comparison between tribo-systems. To rationalize this experimental approach and facilitate the comparison between tribo-systems, normalized sliding condition and crack nucleation fretting maps are introduced. Based on contact mechanics, the sliding transition is quantified using a fretting sliding criterion, and a specific formulation is provided to identify the local friction coefficient under partial slip condition. Cracking, which is mainly observed under stabilized partial slip condition, is analyzed by applying multiaxial criteria and taking into account the size effect. Wear, which is favored under gross slip condition, is quantified through an energy approach. Finally a global methodology is developed by which the sliding condition, the crack nucleation under partial slip condition and the wear kinetics under gross slip regime may be quantified.