Estimation of Friction Coefficient Between Outside Wheel Flange and Rail Considering Influence of Wheel/Rail Wear

The running safety of a railway vehicle against flange-climb derailment is evaluated with the derailment coefficient. A monitoring bogie, which can measure the derailment coefficient during commercial operations, has been developed and condition monitoring of derailment coefficient has been realized. However, the critical derailment coefficient is determined by the friction coefficient between the leading outside wheel flange and rail, which changes due to wayside rail lubrications. In order to evaluate the running safety more accurately, the present paper proposes an estimation method of the friction coefficient of the leading outside wheel flange utilizing the multibody dynamics simulation. By changing the friction condition and repeating simulation in sharp curves, relationship between the given friction coefficients and the calculated wheel/rail contact forces is derived, and look-up table is created from the results. The friction coefficient of the outside wheel can be regressively estimated by inputting the measured contact forces collected with the monitoring bogie into the look-up table. This paper also considers the influence of wheel/rail profiles on the proposed method and presents a modified look-up table made from simulations with the measured wheel/rail worn profiles.