"Wear induced by debris formation and ejection is becoming a critical problem in many industrial applications. Fretting wear associated to small oscillating sliding displacement is considered as a plague in many contacted systems submitted to vibrations loadings (aeronautics, energy, biotechnology, nanotechnologies etc …). Hence, there is a critical interest to formalize wear degradations and wear rates to predict the contact endurances. Unfortunately, the current formalisms (Archard's law etc …) are still empirical and can take into account the contact size effect. Developing a micro-macro description of fretting wear phenomena, the applicant has recently introduced an extended energy wear formulation which permits to take into account the contact size effect. However, there is now a critical interest to optimize this approach for micro-nano contact scales. Hence, the objective of this IOF project is to extend this research through a 14 months mobility at the Department of Materials Science & Engineering (Nanolab / Suresh group) of MIT (USA). By coupling experimental and modeling developments our common objective is to develop an unified wear approach to quantify the wear rate from nano to macro contact size ranges. In addition to this scientific objective, this IOF project will permit the acquisition of competencies on nano tribology and research management that will be transferred after the return phase to the LTDS-DFI group (France) headed by the applicant."