Sheet Element Approximation for Numerical Study of Current on Armature and Rail Interface

The armature and rail (A/R) interface is an imperfect contact that is made at discrete asperities at the microscale resulting from high contact pressure. The current distribution of the interface differs significantly from the bulk behavior. In this paper, based on the contact layer model (CLM) and the Cooper-Mikic-Yoranovich model (CMYM), sheet element approximation and boundary conditions are proposed to analyze the electromagnetic properties of the A/R interface. Assuming zero gradients of the magnetic vector in the thickness direction, there are two ways for the approximation, which are mathematical approximation (MA) and physical approximation (PA). Results from both methods show high agreement, consistent with results from slit boundary conditions. Current distributions on both stationary and sliding A/R interfaces are numerically investigated. On the stationary interface, current diffuses from the edges to the central part of the real contact area, whereas on the sliding interface, current concentration occurs at the trailing edge due to the velocity skin effect (VSE). Furthermore, the contour of the current distribution aligns with the erosion pattern observed in experiments, validating the accuracy of the computational method.