Hunting stability improvement for high-speed trains through modification of wheel/rail contact relation

The hunting stability is an important issue for vehicle systems that determines the maximum operating speeds of the high-speed trains. In this paper, the research background for the three abnormal vibration phenomena of the high-speed trains caused by the hunting stability problems, including the "VIP Chair Shaking," "Bogie Alarm," and "Carbody Sway" problems, are introduced. Firstly, the reason why the vehicle hunting motion loses its stability is investigated from the viewpoint of wheel/rail contact relation. Then, a modified wheel profile is recommended in order to solve or relieve the stability problem, in which the slope at the flange root for the original wheel profile is decreased and the slope at the wheel tread end is increased. Furthermore, the numerical model for a high-speed passenger car is established to verify the dynamic performance of the modified wheel profile. Finally, the dynamic test for the vehicle equipped with the modified wheels is carried out using full-scale roller test rig to validate the theoretical analysis. It can be seen from simulations and validation tests that the wheel/rail contact relation and the dynamic performance including the hunting stability and ride comfort for the high-speed vehicle with the modified wheel are improved significantly compared with the original wheel.