High Frequency Behavior of Electrical Contact Subjected to Vibration Induced Fretting Corrosion
Type of DegreePhD Dissertation
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expansion/contraction, mechanical vibration, or by a combination of these two mechanisms. Recently there has been considerable work on this topic, including experimental investigations and model development work. Much of the previous work has been focused on the increase of electrical resistance between the blade and receptacle of power and signal connectors. As the speed of data transmission increases, however, not only the contact resistance, but also the contact impedance is supposed to be considered a significant quantity in the high frequency data transfer. The physical separation of two sides of the contact interface by the corrosion products produces a capacitive effect that has not been comprehensively studied before. The present study seeks to explore this phenomenon and develop an understanding of its significance. In the author's work, the first project investigated the influence of vibration induced fretting corrosion to contact impedance. With a higher degradation level, a remarkable capacitive characteristic was observed at fretted contacts. A corresponding statistical model was developed iii to account for the fashion of development of contact capacitance. The second project studied the impact of fretting corrosion to signal transmission at a radio frequency spectrum. As contact resistance increased, the metallic contact gradually lost the transmission capability especially at a low frequency range. Using a network model, this phenomenon was explained by the capacitive property of degraded contacts as a result of build-up of insulating layer at the contact interface. In the last study, it was revealed that the dynamics of fretting motion influenced AC signals through the oscillation of contact resistance. Due to non-uniform accumulation of corrosion products at a contact area, contact resistance tends to have higher values at ends of a fretting track. This behavior resulted in intermodulation products when an AC signal passing through an electrical contact at the occurrence of fretting motion. Through this series of studies, experiments and simulation have been performed to investigate the phenomenon and to develop an understanding of the way fretted electrical contact influences RF data transmission. Of particular interest is the effect on signal phase and frequency response across the contact interface and how these effects might be employed to monitor the health of connector systems used for communication signals.