Investigation of plastic deformation and damage at the wheel–rail interface under thermal contact conditions via peridynamics

• An elastoplastic peridynamic model was established to simulate flexible wheel-rail thermal contact. • Validation was conducted by comparing the results of the peridynamic model and finite element model. • Thermal softening is the primary cause of surging plastic deformation and wear. • This study reveals the friction heat-dominated mechanism of wheel-rail surface scratches. The thermomechanical loads generated by sliding contact markedly exacerbate plastic deformation and even induce damage at the wheel-rail interface, thereby accelerating the failure of the wheel-rail system. This study establishes a flexible wheel-rail model using ordinary state-based peridynamic (PD) thermomechanics to explore the thermomechanical response and damage mechanisms of the wheel-rail interface under sliding contact. Model validation was conducted by comparing thermomechanical results from the PD model with those from the finite element model. A parametric study using the established PD model was conducted to investigate the effects of creepage, friction coefficient, and vehicle speed on the plastic deformation and damage behavior of the wheel-rail interface. The increase in frictional heat flux, driven by higher levels of creepage, friction coefficient, and train speed, results in a sharp elevation of the contact temperature (approximately 450 to 1450°C). Interfacial heat conduction results in comparable temperatures between the wheel and rail surfaces. The strength reduction induced by thermal softening led to excessive plastic deformation at the wheel-rail interface, and ultimately to material wear. In critical sliding contact conditions, the temperature exceeds 800°C, followed by a rapid cooling rate exceeding 1000°C/ms, leading to thermal-induced martensitic white etching layers formation. The microstructural characteristics of the field rail samples provide qualitative support for the thermomechanical damage features predicted by the PD model.