Wheel-rail thermo-mechanical coupling characteristics of different positional vehicles in heavy-haul train under emergency braking

Abstract

To investigate the effects of material temperature variation on wheel-rail contact behavior of different positional vehicles in heavy-haul trains, this study established two train-track coupling dynamic models: one incorporating wheel-rail thermo-mechanical coupling and the other ignoring thermal effects. The thermo-mechanical model accounts for material’s temperature-dependent properties and three-dimensional creepage, enabling more realistic simulation of wheel-rail interactions. Dynamic responses of locomotives and wagons under the emergency braking conditions are compared between varying cross and vertical sections. Results show that under emergency braking, higher braking force and the wheelset yaw angle lead to greater locomotive temperature rise. Wheel-rail contact temperatures of front wagon are 12.8%-16.6% higher than that of middle/rear wagons due to braking force saturation. Longitudinal creep force differences between two models drop from 8 kN (locomotive) and 2.5 kN (front wagon) to less than 1 kN with curve radius increasing, while lateral creep force differences for front wagons reach 52% due to wheelset yaw angle and braking force distribution. It is recommended to strengthen rail inspection and maintenance in sections with high traction/braking frequency and small curve radii. Prioritizing the wheel-rail materials of locomotives and front wagons will be helpful to avoid damage hazards and safety incidents caused by abnormal temperature rise. These findings provide a theoretical basis for engineering applications of thermo-mechanical dynamic models in heavy-haul trains.