2019 年 85 巻 876 号 p. 18-00394
This paper presents the experimental results of the transient characteristics of the tangential force between small cylindrical specimens assumed as a wheel after re-profiling and a new rail respectively, generated in the case where the frictional force is applied to the wheel/rail contact surface repeatedly, and also the results of the numerical analysis of the influence of the wheel/rail contact surface properties on the running performance of the railway vehicles. In the experiments, the tangential force characteristics in case of sweep under the different longitudinal slip change rate conditions have been obtained by means of a twin-disk sliding-frictional rolling machine equipped with the environmental device in RTRI. The experimental results show that the tangential force coefficient is smaller in the range of a low longitudinal slip ratio compared with the Kalker’s theoretical characteristics that are obtained by applying the Levi-Chartet’s formula of saturation, which are the steady characteristics of the tangential force, in case of the contact surface close to that after re-profiling, and that the tangential force coefficient becomes large when the frictional force is applied to the wheel/rail contact surface repeatedly. This means that the coefficient of friction becomes large due to the repetition of the rolling and sliding friction. In addition, in order to investigate the relation between the contact surface properties and the running performance of the railway vehicle, a numerical analysis using a simple wheel-rail dynamic model was carried out by comparing Kalker’s theoretical value with the experimental values. As a result of the numerical analysis, it’s clarified that in case of the power running, the wheel after re-profiling is more slippery than that without re-profiling after long run in the range of a low longitudinal slip ratio.
