Practical wheel/rail tangential contact force model for vehicle dynamics analysis under running in rainy conditions

Abstract

This paper describes a practical wheel/rail tangential contact force model for railway dynamics analysis under running in rainy conditions. In our previous studies, it was confirmed that experimental results of tangential contact force measurement are agree well with Kalker’s rolling contact theory under dry condition with low humidity around contact surfaces. Here, it can be considered that if the ambient humidity around the contact surface become high infinity, the contact surface is under wet lubrication conditions. On the basis of this assumption, in this study, a practical estimation technique for characteristics of tangential contact force under running in rainy conditions is proposed by combining the relationship between the adhesive coefficient and velocity measured on running experiments using actual railway vehicles and Kalker’s linear rolling contact theory. Therefore, to verify the proposed technique, the tangential contact force measurement experiment using a twin-disk rolling sliding machine was carried out. As a result, it is confirmed that estimated formulae based on the proposed technique are well agreed with experimental results even under different velocity conditions, comparing the relationship between tangential contact force coefficient and slip ratio. From these verified results, the proposed technique is considered to be a practical wheel/rail tangential contact force model for vehicle dynamics analysis under rain conditions, because the proposed technique has the advantage of low calculation cost and can be easily applied to vehicle dynamics analysis based on multibody dynamics theories.