Analysis of wheel rail vibration response caused by wheel flat of heavy freight vehicles under braking conditions

With the development of heavy haul railway in China, the axle load of heavy haul freight vehicles is increasing, and the problem of wheel flat is also increasingly prominent, which leads to dramatic increase in dynamic wheel rail loads. In this paper, a rigid-flexible coupling dynamic model of heavy haulfreight vehicle-track was established, and the influence of wheel flat on vertical force and longitudinal creep between wheel and rail was investigated under different braking conditions of heavy haul freight vehicles, and the limit value was calculated. Results show that the PI and P2 forces of the vehicle increase with the increase of the length and speed of the wheel flat, and the emergency braking condition is greater than the normal braking condition. The wheel/rail vertical force of the empty car is far less than that in the load car, but the wheel/rail vertical force fluctuation of the empty car will be greater under the effect of the flat. On the other hand, braking of the vehicle will lead to changes in the longitudinal creepage and the longitudinal creep force. At the same time, the longitudinal creepage and the longitudinal creep force will fluctuate under the action of the wheel flat. The larger the wheel flat, the greater the fluctuation. According to the wheel/rail vertical force and wheel load reduction rate specified by the state, the wheel flat limit value of the vehicle under different working conditions was calculated. Combining the empty and load vehicles as well as the braking conditions, the limit value of wheel flat of the heavy haul freight vehicle was determined as 38 mm. The study will provide relevant guidance for the operation and maintenance of heavy haul freight vehicles. © 2024 Chinese Vibration Engineering Society. All rights reserved.