Estimation of wheel/rail adhesion coefficient under wet condition with measured boundary friction coefficient and real contact area

This paper describes how to improve the prediction method of the adhesion coefficient by means of the experimentally estimated boundary friction coefficient obtained by two kinds of twin-disc rolling contact machines and the ratio of real contact area to nominal contact area (RCA/NCA) obtained by ultrasonic measurement. The previous prediction method that the authors had already proposed in the last paper was based on Greenwood-Tripp's rough surface contact model; however, in this study, the authors adopted Lee & Ren's rough surfaces contact model and focused on the RCA/NCA measured by ultrasonic wave in order to predict the adhesion coefficient under wet conditions with the actual surface contact conditions. As a result, regarding the tendency of adhesion coefficient decreasing with an increase of running speed, a good agreement has been obtained between the results obtained by the prediction method proposed in this study and the measured results obtained by the field-test of Japanese Shinkansen vehicle (series 200).