Performance of a shape memory alloy coil-shaped clamp for enhanced normal force in pin-and-receptacle electrical connectors

Electrical connectors can experience a significant degradation in performance due to fretting corrosion, which is particularly problematic when the connector undergoes vibration. Fretting corrosion can be reduced or eliminated if the relative motion between the pin and receptacle is reduced or eliminated. One practical means of reducing the relative motion is to increase the normal force between the pin and receptacle. Unfortunately, increasing the normal force has traditionally implied increasing the insertion and removal forces required for mating and separation of the pin and receptacle. In this paper we describe a connector in which the normal force between the pin and receptacle is increased after the connector is mated and decreased before separation. We implement our approach for connectors that are put in service in elevated temperature environments by placing a coiled shape memory alloy (SMA) wire around the receptacle part of a standard pin-and-receptacle connector. We experimentally demonstrate the efficacy of this approach by quantifying the increase in normal force between the pin and receptacle and by showing a substantial increase in connector lifetime in a vibratory environment.