Numerical and experimental study of the contact resistance for high copper alloys in force domain 1-100 N
Résumé
High copper alloys were required by the industry to improve mechanical and electrical contact resistance for connecting device. This work addresses the electrical contact resistance law versus force in the range (1-100 N) for sphere/plan shapes. The designed samples are submitted to indentation (static contact) and insertion (sliding contact). Experimental power law of contact resistance versus forces was obtained where the law parameters are well related to electrical resistivity, Young modulus, yield stress... Previous analytical relationship R(c) = f(F(c)) in the literature and finite element simulation code are used to discuss the origin and the validity of such practical power law. Nevertheless the analytic expression are found unsatisfactory, the numerical model gives some agreement with this previous experimental law. However better convergence between numerical and experimental data was obtained in indentation when the surface topography is considered. The obtained results are a useful tool to evolve compromise between the electrical and mechanical aspects for a high loading contact. The main statement is that numerical model including the real topography and roughness is robust so it can be used in different contact shape and complex design for contact resistance evaluation. Finally, depending on the hardness and the resistivity, these uncoated materials were found to act on fretting apparitions and its level.