Analysis of temporal and spatial contact voltage fluctuation during fretting in automotive connectors

Our study is focused on contact voltage fluctuations during fretting with small amplitudes of a few tens microns which generate damage of the contact of connectors. A contact composed by a pin and a curve female part are submitted to vibration cyclic of 25micrometer at 100Hz and supplied with current ramp from 0.1mA to 3A in two directions. With the help of fast devices, the voltage and position data acquisition are conjointly made with the common DC contact voltage during fretting. Some unexpected results state that voltage fluctuation occurs in the different stage of fretting and start at the beginning of test in the insertion direction and located at half of track. These small voltage fluctuations around few mV increased to few hundred millivolts and may reach few volt at ultimate phase of degradation with random distribution along the track. When the motion is stopped the ohmic conduction of such fretting interface is ensured only when the subsequent voltage stay below a sutured value depending on the degradation and current level. It is found that the common three phases of degradation have a different saturation voltage which appears at higher and higher current and induce voltage breakdown. Regarding that symmetric characterises is obtained in two the directions current ramp the semiconducting behaviour effect of oxide layers on debris particle is negligible. As voltage-current experimental data was well fitted to similar equation of granular material conduction we have deduced the fitting parameters (Vl and I0) of interface.