Investigating the effect of rail profile deviation on hunting instability of high-speed railway vehicle under multi-parameter coupling

Small changes to wheel-rail profiles can have a significant impact on the equivalent conicity and vehicle dynamics. Previous research has focused mostly on worn wheels, however, with little attention to different types of rail profile deviation and their influences on vehicle dynamics. Therefore, the specific objective of this paper is to investigate the individual and combined influences of various rail profiles and multi-parameter couplings on the hunting instability of railway vehicles. This paper first obtains the distribution law of rail profile deviation from a statistical analysis of several rail profiles with long-term measurements. Then, the equivalent conicity of rail profiles that match the studied wheel profiles, gauges and wheelback distances is compared. The dynamic model for the vehicle has been established. Finally, the measured rail profiles and wheel profiles, as well as the combinations of the gauges, wheelback distances, friction coefficients and key suspension characteristics are integrated into the simulation model to analyze the atypical phenomenon of the carbody hunting and the bogie hunting. According to the findings, rail profile deviation has a significant impact on equivalent conicity and the evaluation of vehicle stability when subjected to multi-parameter coupling, particularly for worn wheels. Therefore, strict limits of rail profile deviation have to be considered in track maintenance for vehicles running at speeds of 300 km/h or higher.