Investigation of Wheel‐Rail Adhesion Performance Under Water‐Contaminated Conditions Considering Interface Geometry

ABSTRACT In this paper, a numerical model of wheel‐rail adhesion under water‐contaminated conditions is established. Wheel‐rail profile and surface roughness are included to describe wheel‐rail adhesion behaviour more accurately. The Average Reynolds equation, Boussinesq elasticity equation and the Greenwood‐Tripp (GT) asperity contact formula are coupled to resolve mixed elastohydrodynamic lubrication (EHL) problem at the wheel‐rail interface. The proposed model is validated by comparing the calculated wheel‐rail adhesion coefficients with the experimental outcomes. Numerical simulations are carried out to observe the influence of running speeds, surface roughness and axle loads on the wheel‐rail adhesion with water layer at the interface. In addition, the results of the simplified model based on the elliptical assumption were compared with those of the precise model that considers the actual wheel‐rail contact geometry. The study results indicate that using the elliptical simplification can lead to significant errors in the estimation of wheel‐rail adhesion. Therefore, when analysing wheel‐rail adhesion behaviour, the variations in the geometric shape of the wheel‐rail contact surface should not be neglected.