The adhesion force between rail and wheel is one of the important factors for proceeding towards the realization of high-speed railway. On the other hand, it is supposed that the water film formed between the rail and wheel has a remarkable influence on the adhesion force under rainy condition at higher speeds. In this paper, taking Bett and Cappi's viscosity values of water, which show quite a different behaviour from the viscosity of oil, the influence has been investigated of important factors such as rolling speed, contact pressure and temperature on water film thickness for a smooth surface by applying elastohydrodynamic lubrication theory. Based on the numerical solutions, an empirical equation has been developed for water film thickness relating to rolling speed, load and material parameter by using a linear regression method and comparing it with other authors' works on a lower material parameter or elastic± isoviscous contact. Furthermore, in order to understand the influence of the above factors and the surface roughness on the adhesion force, adhesion coefficients have been calculated on a trial basis in the case of rough surface contact under limited conditions, and the theoretical results have been compared with the measured values of the tests on Japanese Shinkansen vehicles in the field.
The effects of factors such as rolling speed, contact load, water temperature, and surface roughness on the adhesion coefficient between wheel and rail under wet conditions were investigated theoretically by adopting elasto-hydrodynamic lubrication theory and rough surfaces contact theory [1]. It was found that the water temperature and the surface roughness greatly affect the adhesion performance comparing the other factors. This paper describes an experimental investigation on the effect of water temperature on the adhesion coefficient to verify the significant effect of the water temperature on the adhesion coefficient. The experimental results indicated that a rise in water temperature causes an increase in the adhesion coefficient, which was qualitatively consistent to the numerically calculated results in the previous paper [1].
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