Mechanical suppression of EMU carbody chattering via traction-braking torque strategy

Carbody chattering in electric multiple-unit (EMU) trains, a 10 Hz low-frequency vibration caused by wheel-rail hunting instability, severely compromises ride comfort and operational safety. This study reveals that wheel-tread depression wear combined with rail profile variation induces nonlinear degradation of wheel-rail contact conicity, reducing bogie hunting modal damping to near-zero and triggering synchronous coupling with the carbody’s 10.12 Hz diamond-shaped deformation mode. To address this, an axle-based traction/braking torque control strategy is proposed to dynamically regulate wheel-rail creep force without structural modifications. By applying symmetric torque pairs to each axle, the strategy increases the bogie hunting damping ratio from near-zero to over 0.10 at 160 km/h, shifts the hunting frequency to 10.75 Hz for resonance decoupling, and reduces carbody chattering acceleration by 62%. This improves the Sperling ride index from Level 3 (Qualified) to Level 1 (Excellent), while achieving zero axle load transfer under center-of-gravity shifts and outperforming bogie-based control in vibration suppression robustness. Validated via multi-source testing, root locus analysis, and rigid-flexible coupling simulations, the strategy requires no hardware retrofits, offering a scalable solution for high-speed EMU carbody chattering control.