Numerical investigation on wheel-rail adhesion under water-lubricated condition during braking.

Purpose: The purpose of this study is to develop a 3D wheel-rail adhesion model under wet condition, which considers the generated surface roughness topography and the traditional braking procedure for high-speed trains. Design/methodology/approach: Wheel-rail adhesion has an important effect on the braking ability of railway vehicle. Based on the deterministic mixed lubrication approach, the model was solved to get the adhesion characteristics of the train during braking. The elastic deformation was calculated with the discrete convolution and fast Fourier transform method. The simulation results of adhesion coefficient were compared with the experimental values. The wheel-rail adhesion characteristics of train braking at several different initial speeds were investigated. The effects of the time-step length and roughness orientation on the contact load ratio were also discussed. Findings: The results show that the adhesion coefficient of the numerical model is in good agreement with the experimental results. At the instant of braking, the adhesion coefficient drops to a lower adhesion level, the value of adhesion coefficient is lower than 0.06, especially at a higher speed (200, 300 and 400 km/h). Originality/value: It can provide a better understanding of the low adhesion phenomenon of train braking under wet condition. Peer review: The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-02-2023-0040/ [ABSTRACT FROM AUTHOR]