Numerical analysis for the influence of water film on adhesion between rail and wheel

Abstract

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.

Disc machine testing to assess the life of surface-damaged railway track

“…These two fluid film thickness values have been estimated using the regression equations of Dowson and Higginson [13] for oil and Chen et al [14] for water. The results are shown in Table 4.…”

The effects of surface defects on the fatigue of water-and oil-lubricated contacts

“…During the first stage it propagates through the surface deformation zone (about 10 µm deep). Then the crack turns downwards by a further [25][26][27][28][29][30][31][32][33][34][35] o and grows to a depth of around 300-400 µm . The branches of crack appear to grow at around 90 o to the main crack.…”

“…Chen et. al [25] have developed a similar approach based on numerical results with low viscosity fluid lubricants: …”

Effect of water temperature on the adhesion between rail and wheel

“…Their experimental results showed a similar tendency to those that described in references [2] and [3] regarding the effect of rolling speed on the adhesion coefficient, and indicated that heavy axle loads gave slightly higher adhesion coefficients. Chen et al [1,5] simulated the adhesion coefficient between wheel and rail by applying elasto-hydrodynamic lubrication (EHL) and rough surfaces contact theory. Not only the rolling speed, the water temperature, asperity height and asperity profile of surfaces also had significantly effects on the adhesion coefficient.…”

“…To verify the effects of water temperature on the adhesion coefficient obtained by theoretical investigation in references [1] and [5], a number of experiments have been conducted on a twin disc rolling contact machine under wet conditions at different water temperatures. The water temperature has been clarified to have a significant effect on the adhesion coefficient by the experiments, which is qualitatively consistent to the theoretical results.…”