Analysis of Vibration Transmission and Noise Correlation Characteristics of Metro Vehicles

To address the intensified component vibration, degraded vibration transmission, and noise pollution in metro vehicle systems induced by wheel–rail excitation, this study takes a type-A metro vehicle as the research object. Acceleration and acoustic pressure sensors were installed at key locations of the vehicle system to acquire the vibration responses of major components, as well as the noise characteristics, both trackside and inside the carriage during operation. First, the time-frequency characteristics of vibrations in various components were analyzed to elucidate their transmission behavior in the time-frequency domain. Second, the Hilbert–Huang transform (HHT) was employed to derive amplitude-frequency transfer functions between components, thereby characterizing the transmission properties under typical operating conditions, including constant-speed cruising, traction acceleration, and braking deceleration. Finally, dynamic time warping (DTW) was applied to synchronize the vibration and noise signal sequences, and the correlation between noise and axle box vibration was quantified in the time domain using the Pearson correlation coefficient. The results demonstrate that axle box vibration induced by wheel–rail excitation is significantly attenuated as it propagates through the suspension system to the interior floor. The amplitude-frequency transfer characteristics between components exhibit similar trends across different operating conditions. The primary and secondary suspension systems effectively isolate high-frequency and low-frequency vibrations, respectively. The Pearson correlation coefficients between axle box vibration and wheel–rail noise, and between axle box vibration and interior noise, are 0.8863 and 0.8714, respectively, indicating a strong correlation between vibration and noise generation. The findings of this study provide valuable technical support for suspension system optimization, wheel reprofiling, and the mitigation of vibration and noise in metro vehicles.