Abstract
We present a detailed investigation of the mechanism of metro wheel polygonal wear using on-site experiments and numerical simulation. More than 70% of metro wheels exhibit 6th–8th harmonic-order polygonal wear; the excitation frequency of the polygonal wear is located in the 50–70 Hz interval at an operating speed of 65–75 km/h. To determine the root cause of the polygonal wear, a dynamic train behavior test is conducted immediately after wheel reprofiling. The results suggest a natural mode resonance in the vehicle/track system, whose frequency coincides with the passing frequency of the 6th–8th order polygonalization. The magnitude of the resonance increases significantly when the vehicle runs on a monolithic concrete bed with DTVI2 fasteners. Thus, a corresponding coupled vehicle/track dynamic model is established and validated by comparing the calculated frequency response functions (FRFs) of tracks and dynamic responses of axlebox acceleration with the measured values. Using multiple timescales, the dynamic model and Archard wear model are integrated in a closed loop for long-term polygonal wear prediction. The simulated and measured evolution of polygonal wear show good agreement. By combining simulation results and experimental data, we suggest that the P2 resonance is the main contributor to the high amplitude of wheel/rail contact forces in the 50–70 Hz frequency range and the reason for subsequent polygonal wear. Parametric studies show that the dominant order decreases as vehicle speeds increase, representing a “frequency-constant” mechanism. The wheelset flexibility, especially the bending mode, would aggravate the wheel/rail creepage and further accelerate the formation of polygonal wear. Higher rail pad stiffness will increase P2 resonance frequency and shift the dominant wheel to higher polygonal orders.
Highlights
Wheel polygonalization, known as wheel corrugation or periodic out-of-round (OOR) wheels, is one of the greatest concerns in railway vehicles and is defined as periodic radial tread irregularity around the circumference superimposed on a constant wheel radius [1]
Pallgen [3] made a contrasting analysis on the wavelength of wheel polygonalization in different types of ICE train wheels; they found that the third order was the dominant order on solid steel wheels, while the second order dominated for rubber sprung wheels
Train wheel polygonal wear is a significant concern in railway engineering, and the mechanism behind it remains elusive
Summary
Known as wheel corrugation or periodic out-of-round (OOR) wheels, is one of the greatest concerns in railway vehicles and is defined as periodic radial tread irregularity around the circumference superimposed on a constant wheel radius [1]. Wu [16] investigated the dynamic response of a high-speed vehicle under 18th order polygonal wear. Rough extensive experiments and numerical simulation, Zhang [18] evaluated the effect of OOR on the noise of high-speed trains and reported that wheel polygons of higher order lead to more serious wheel/rail and interior noise. E results suggested that the original wheel OOR will exhibit large normal force variations and excite the bending oscillation of the wheelset, which will further lead to lateral slip and lateral material excavation between the wheel and rail. A detailed coupled vehicle/track model validated by experimental data was established by Johansson and Andersson [25], who used it to investigate the development of OOR based on an initial irregularity spectrum derived from measurements conducted on new wheels. By combining the experimental and simulation results, we identify the root causes of the polygonalization
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