A transient three-dimensional wheel-rail adhesion model under wet condition considering starvation and surface roughness

Abstract

The objective of this paper is to propose a new three-dimensional wheel-rail adhesion model under wet condition which considers insufficient water supply, the measured surface roughness and dynamic effect of the vehicle and track coupling system. Firstly, a longitudinal vehicle/track coupling dynamic model (LVTDM) was developed to obtain the dynamic parameters and contact points trace in curved track. Then, an improved numerical method was used to solve the transient general starved Reynolds equations, utilizing the input dynamic parameters acquired from the LVTDM. The numerical model was validated under the starved steady condition for the smooth surface and subsequently applied to investigate wheel and rail contact behaviors under wet condition. The results show that the effect of starvation on the wheel-rail rolling contact behaviours becomes significant when the inlet film thickness is less than 1000 nm for smooth surface. The numerical results were also compared with experimental results conducted by a high-speed tribology facility. In addition, the time-dependent characteristics of the wheel-rail rolling contact were obtained at different time instants. The transient wheel-rail adhesion characteristics under wet condition for different train speeds were obtained. The transient wheel-rail adhesion modeling results shows that the train speed has a significant effect on the adhesion ability.