On the formation mechanism of high-order polygonal wear of metro train wheels: Experiment and simulation

Abstract Severe high-order polygonal wear has been found on metro train wheels of one metro line in China, which causes considerable vibration of vehicle components and disturbing interior noise. Field tests and numerical simulations were conducted to investigate the formation mechanism and key influencing factors of wheel high-order polygonisation. Wheel out-of-roundness (OOR), vibration behavior of vehicle components, and rail surface irregularities were tested. On-site measurement results indicate that the wheels exhibit 13th- to 16th-order polygonal wear. The dominant wavelengths are about 165–203 mm. The experimental results show that the wheel polygonisation is related to the first-order bending vibration of the wheelset and the P2 resonance generated on ladder sleeper tracks and steel spring floating slab tracks. A long-term wear model was developed to further study the cause of wheel polygonisation, which included a vehicle–track coupled dynamic model, considering the flexibility of the wheelset and track, as well as a wear model. The effects of operating speeds, P2 resonance frequencies for different tracks, and wheelset flexibility on the development of wheel polygonisation were investigated. Based on the experimental and simulation results, it is further believed that the P2 resonance is the main cause of the higher-order polygonal wear of wheels, and the first-order bending vibration of the wheelset can exacerbate the wheel polygonisation.