Graphical Abstract Figure
() Plots of and in closed forms (with and without discharging) and solved by the discharging numerical model at the contact phase with and V. The dash-dotted line indicates the periphery of the contact area. () Analytical solutions of with and without discharging and the modified Paschen law.
Graphical Abstract Figure
() Plots of and in closed forms (with and without discharging) and solved by the discharging numerical model at the contact phase with and V. The dash-dotted line indicates the periphery of the contact area. () Analytical solutions of with and without discharging and the modified Paschen law.
Abstract
Electrical contact is fundamental to almost every aspect of modern industry, including the fast-growing electric vehicle industry. In metallic contacts in atmospheric conditions, most of the electrical current passes via the microjunctions formed between two electrodes. The classic electrical contact theory predicts an infinite current density at the circular contact periphery. In the present work, we explore the influence of the dielectric breakdown of air outside the contact area on the electrical contact interface. Incorporating the discharging boundary condition governed by the modified Paschen law, we develop the numerical model as well as two sets of closed-form solutions for low applied voltage cases where two electrodes are in solid–solid contact and complete separation, respectively. For the Hertzian contact, the present work theoretically proves that the ignorance of discharge can lead to a singular current density at the contact periphery and an overestimation of the electrical contact resistance. The current density monotonically increases along the radial direction to a finite value at the contact area periphery and is followed by a monotonic drop within the discharge zone. The present study serves as a foundation for the modeling of discharging rough surface electrical contact and sheds light on the machine element surface damages caused by the electrical discharge machining.
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