Finite Element Analysis of the Thermo-Mechanically Coupled Wheel–Rail Contact Response Under Rolling and Full-Slip Conditions

During frequent starting and braking of metro vehicles, wheel–rail contact may change from pure rolling to full slip, and the frictional heat generated at the interface can induce localised rail damage such as rail burns. Because the motion state and the thermal input vary together in service, their separate contributions to the contact response are difficult to identify. To separate them, a three-dimensional elastic–plastic finite element model of a Type B metro wheel and rail was established and four cases were computed, forming a 2 × 2 factorial combination of two motion states (pure rolling and full slip) and two thermal states. The temperature field was imposed as a prescribed railhead boundary rising from 22 °C to 50 °C, applied identically under both motion states as a control variable, rather than solved from frictional heating. Under an 80 kN wheel load, the maximum rail equivalent stress of the four cases is 541.9, 596.3, 623.1 and 679.5 MPa, all exceeding the 457 MPa yield strength of U71Mn rail steel and indicating shallow localised plasticity in the contact patch. Full slip changes the peak contact pressure by less than 2% but raises the maximum rail equivalent stress by 14–15%, because the interface passes into full sliding and the high-stress zone moves towards the rail surface; the 28 °C temperature rise concentrates the contact and raises the stress by a further 9–10%. The factorial interaction term is +2.0 MPa, below 4% of either main effect. An analytical estimate shows the imposed thermal load to be a conservative lower bound for continuous sliding.