Edge-localization damage mechanism in electrical contact at the micro-asperity scale

Damage accumulation at current-carrying electrical-contact interfaces is a major cause of performance deterioration and reliability loss in connectors, relays, and slip-ring systems. Here, we report a fully coupled electro-thermo-mechanical analysis of damage formation at the micro-asperity level. A finite-element framework simulates the evolution of current density, temperature, and mechanical deformation in hemispherical asperities, incorporating temperature-dependent material properties. The results reveal pronounced edge localization of all three fields, including current crowding, steep temperature gradients, and plastic deformation at the asperity perimeter. These coupled field localizations drive edge-preferential softening, material pile-up, and crack initiation, consistent with experimentally observed marginal convexity and fracture features. The findings provide a rigorous, physics-based interpretation of failure patterns in electrical connectors, relays, and microelectromechanical systems, offering insights for designing more robust contact interfaces.