Assessment of fretting failure models of electrical connectors

Two competing models of the effects of fretting corrosion on contact resistance have been investigated. The asperity contamination model explored corrosion product mixing into asperity metals: asperity metals evolved into a metal/salt composite with elevated resistance at the asperities. The valley filling mechanism assumed wear debris dropped into surface valleys: after valleys filled, surfaces separated and contact resistance escalated. Both mechanisms predicted correct orders of magnitude for the number of cycles to high resistance failure. Each mechanism was based on a material balance and incorporated fretting vibration amplitude and frequency, changes in material properties induced by corrosion, plating thickness, loads, and asperity deformations. In this paper the models are extended to include other important factors such as imperfect packing of wear debris dropping into in valleys, wear of asperities, plating deterioration, effect of asperity contamination on further asperity corrosion, effect of normal force on debris wear, contact healing via fritting, and second stage resistance fluctuations.