Analysis of carbody abnormal low-frequency vibration in high-speed EMU caused by thin-flange wheel profile

Carbody Abnormal Low-Frequency Lateral Vibration (CALFLV) represents a critical operational challenge for high-speed EMUs. This phenomenon was recently observed in a high-speed EMU when negotiating 2200 m-radius curves at approximately 180 km/h on a passenger-dedicated line in China. To investigate the mechanism and propose effective countermeasures, field tests were conducted to measure carbody lateral acceleration and wheel profiles, and a multibody dynamics model was established to simulate the EMU’s dynamic behavior. Analysis reveals that the interaction between thin-flange wheel profiles and the 60N rail results in low equivalent conicity under large wheelset lateral displacements. Once the equivalent conicity drops below 0.09, carbody hunting instability is triggered and manifested as a lateral harmonic vibration at approximately 1.2 Hz. Countermeasures were implemented by modifying the throat-root region of thin-flange wheel profile in combination with adjusting the primary longitudinal stiffness to 40 MN/m. Post-implementation field validation shows that the maximum lateral Sperling index during curve negotiation is reduced by approximately 0.5, demonstrating the effectiveness of the proposed countermeasures in mitigating CALFLV. This study provides new theoretical insights and engineering solutions to address similar carbody vibration issues in high-speed railway vehicles.