Numerical analysis of high-speed wheel/rail adhesion under interfacial liquid contamination using an elastic-plastic asperity contact model

Abstract

The objective of this paper is to investigate the high-speed wheel/rail adhesion under interfacial liquids contamination using a numerical model. This model considers the rheological property of interfacial liquids, elastic-plastic deformation of microasperities contact and the temperature across the film thickness. The pressure and the temperature fields can be obtained. The effects of train speed, surface roughness parameters, characteristic shear stress, and the slip ratio are investigated. Furthermore, the present model is compared with the elastic model and the elastic-plastic model without considering the thermal effect. The numerical results show that the train speed and temperature affects the wheel/rail adhesion significantly.

Numerical investigation on the high‐speed wheel/rail adhesion under the starved interfacial contaminations with surface roughness

“…This result is consistent with the flooded case. 16 It can be found that the temperatures in the cavitation areas are equal to the ambient temperature. That is because the liquid pressure in the cavitation area is zero.…”

“…It should be noticed that the wheel/ rail contact area is divided into the pressurised and the starved regions, which is different from the flooded case. [13][14][15][16] The interfacial liquid is assumed to completely fill the gap in the flooded region (pressurised region). Nevertheless, the supply of the interfacial liquid in the inlet region and outlet regions, which are called as cavitation regions, cannot build the elastohydrodynamic lubrication (EHL).…”

“…The interfacial liquid pressure is governed by the average Reynolds equation considering surface roughness, non-Newtonian property, and thermal effect for a steady-state line contact. 16 However, this equation is based on the fully flooded condition. In fact, the starved condition may happen during the railway operation condition.…”

“…Since the starvation and cavitation are involved in the present model, the numerical procedure is different from the flooded case. 16 The liquid pressure P and the fractional film content θ were treated as separate variables in a Gauss-Seidel line relaxation. The fractional film can be obtained from the following iteration form 27 :…”

“…The stochastic model based on the average flow theory had been developed to analyse the adhesion coefficient under different liquid contaminations. [13][14][15][16] In addition, Tomberger et al used the deterministic model to study the traction coefficient under the wet condition. 17 Most numerical models mentioned above were developed under the assumption of enough inlet water or oil supply.…”