Numerical Simulation of Wheel–Rail Adhesion Under Wet Conditions and Large Creepage During Braking

Low adhesion conditions can lead to significant wheel slip during braking for high-speed trains, resulting in severe wheel–rail rolling contact fatigue issues. The objective of this paper is to reproduce the dynamic wheel–rail adhesion characteristics of high-speed train braking with large creepage using the transient non-Hertzian ECF model under wet conditions and to clarify the underlying mechanisms. The Kik–Piotrowski (KP) model is used to solve the wheel–rail normal contact problem, and the corresponding non-elliptical adaptive method is adopted to modify the ECF model considering time-dependent effects for solving the tangential contact problem. The dynamic large creepage adhesion characteristics of high-speed trains under wet conditions during braking are analyzed. Furthermore, the effect of braking initial speeds and longitudinal creepage variation curves on dynamic adhesion characteristics is discussed. The results indicate that the large creepage adhesion characteristic curve of high-speed trains during braking exhibits a loading stable phase and an unloading stable phase, both of which effectively enhance the utilization of wheel–rail adhesion.