Experimental and numerical analysis of the polygonal wear of high-speed trains

Abstract

High-order wheel polygonal wear results in many problems in track and vehicle systems. To gain insight into its formation mechanism, the relationship between dominating order and vehicle speed and wheel diameter is first analyzed based on the polygonal wear measured at field sites. The measurement data proves that high-order polygonal wear serves as the “fixed-frequency” mechanism. Moreover, the test results of the vibration characteristic of an axlebox show that resonance at 550–650 Hz exists in the vehicle/track systems, which is associated with the formation of high-order polygonalization. Then, a coupled vehicle/track dynamic model is established. By sweeping the frequency excitation, the harmonic behavior of wheel/rail normal forces is evaluated considering a single wheelset model and a bogie model. The results of the two models are compared and indicate that the rail vertical bending modes between the front and rear wheels of the bogie play an important role in the dynamic response of the wheel/rail forces. Particularly, the natural frequency of the third-order rail local bending mode is near the excitation frequency of the high-order polygonal wear. Subsequently, the development of the ideal polygonalization is investigated by introducing the Archard wear model. The results suggest that both the amplitude of the wear depth and the phase difference between the wear depth variation and original polygonalization play vital roles in the enlargement of polygonalization. Using a long-term wear iteration, the growth progress of the typical 20th order polygonal wear on China’s high-speed trains is reproduced. The simulation results indicate that the third-order rail local bending resonance greatly contributes to the periodic fluctuation in the wheel/rail normal forces and further leads to the large periodic wear at approximately 550–650 Hz (19th–23rd orders), the 20th order (577 Hz) among them has the fastest growth rate in each wheel revolution because of the smaller phase difference between the wear depth and the original polygonalization.. In addition, parametric studies show that the dominant order of the polygonal wear largely depends on the vehicle speed and wheelbase. The continuous increase in the stiffness of the railpad shifts the polygonal wear from a high order to a lower order because of the significant P2 resonance. Large railpad damping reduces the growth rate of the high-order wheel polygonal wear.