Research on abnormal flexible vibrations of intercity rail vehicle car bodies and its control based on modal force decomposition

Abnormal flexible vibrations of railway vehicle car bodies frequently occur due to lightweight design, leading to degraded ride comfort. This study systematically investigates the formation mechanism and control strategies for such abnormal flexible resonance in an intercity train, combining experimental testing and simulation modeling. Results show that first-order wheel out-of-roundness (OOR) excites the car body diamond deformation mode via frequency matching, inducing vertical-dominant resonance that impairs ride quality. A validated rigid-flexible coupled dynamics model was developed, and a modal force decomposition method and modal vibration decomposition were proposed to quantify the suspension forces’ contributions to modal excitations, revealing the resonance mechanism. To address the resonance of the diamond deformation mode of the car body, four control schemes were comparatively analyzed: optimizing air spring vertical stiffness, optimizing secondary vertical damper damping, adjusting air spring installation positions, and wheel reprofiling. Feasible measures meeting control requirements were proposed finally.