Experimental and Numerical Investigation into Formation of Metro Wheel Polygonalization

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.

Polygonisation of railway wheels: a critical review

“…15, which is caused by the P2 resonance. The formation mechanism of the wheel OOR reported in [14] was further verified by numerical simulation performed by our research team [75]. Through field investigation, Li et al [17] pointed out that polygonal wear with 7 harmonics in one metro line was also caused by the P2 resonance.…”

“…Kalousek and Johnson [8] (2) P2 resonance Nielsen et al [5], Johansson and Andersson [74], Tao et al [14], Li et al [17], and Cai et al [75] (3) Frictional self-excited vibration of a wheelset-track system Chen et al [76,77], Zhao et al [78], and Wu et al [79] (4) Lower bending or torsional modes of the wheelset Morys [20], Jin et al [80], Yang et al [15], Tao et al [16,[81][82][83], Fröhling et al [84], and Spangenberg [85] (5) Bending vibration modes of the rail or track Johansson and Andersson [74], Wu et al [86], Cai et al [87], Dai et al [88], and Qu et al [89] (6) Excited resonance of the bogie Wu et al [90] and Guo et al [91] (7) Vibration of other components of the bogie Ma et al [92], Liu et al [93], and Fu et al [94] 3. Thermoelastic instability Nielsen et al [5] (Summary) and Vernersson [95,96] with three harmonics.…”

“…The fluctuation of the vertical force between the wheel and rail resulting from the P2 resonance is the root cause of wheel OOR. The higher the vertical railway track stiffness, the higher the vertical force amplitudes and the more rapidly polygonal wear will develop [75].…”

Study on Steady-State Responses of High-Speed Vehicle Using Infinite Long Track Model

“…erefore, the vertical deflection of the rail is discussed in detail here, and the equations of lateral and torsional deflection can refer to [9,14,28].…”

Experimental Investigations on the Effects of Fatigue Crack in Urban Metro Welded Bogie Frame

“…By considering the real wheel out-of-roundness, the considerably fluctuating wheel/rail contact force was observed from a vertical vehicle-track coupled dynamics model [17]. Similarly, by using on-site experiments and simulations, the mechanism of metro wheel polygonal wear was carefully explored at the speed of 65-75 km/h and suggested that the wheelset flexibility could accelerate the polygonal wear and abnormal vibration [19,20]. Such an irregular wheel profile was reasonably believed to produce a detrimental effect on the railway axle and bogie frame [21][22][23].…”