Prediction of electrical contact resistance failure of Ag/Ag plated contact subjected to complex fretting-reciprocating sliding

Electronic connectors are extensively used in the car industry. However, due to engine vibration, fretting wear damage can decay the electrical contact resistance. In addition to small fretting oscillations, the connectors are subjected to clipping/unclipping, which also affects the Electrical Contact Resistance (ECR) endurance (i.e., Nc fretting cycles when ΔR>ΔRc=4 mΩ). To investigate this complex tribological process, an homogeneous Ag-Ni / Ag-Ni (2 µm) contact was subjected to constant fretting sliding (δ*g=±9 µm) combined with intermittent millimetric reciprocating sliding. The analysis showed that, by transferring silver material from the reciprocating track to the fretting scar, ECR endurance was linearly increased. The larger the reciprocating stroke (D from 0.25 mm to 1.5 mm), the greater the endurance. Besides, if the Nf fretting period between reciprocating sliding sequences was too long, the positive effect of the reciprocating was reduced. Expressing both reciprocating silver transfer kinetics and fretting wear rates, a global model of ECR endurance is proposed.