Vibration and noise characteristics analysis and evaluation methods for maglev transportation system vehicles

A scheme for detecting and evaluating vibration and noise data of maglev vehicles was proposed, and the self-developed portable on-board device was employed to collect vibration and noise data of maglev vehicles at low cost and high frequency. The attitude deviation of the inertial sensor coordinate system was corrected, and the vibration characteristics of maglev vehicles were analyzed. The running quality of maglev vehicles was evaluated by adopting the ISO 2631-1:1997 weighted acceleration, Sperling ride-comfort index, and A-weighted sound level, and the speed and mileage information from the measured data were autonomously estimated. The results show that the vertical correction angles of the on-board device for the Shanghai and Changsha maglev systems are 0.08° and 0.95°, respectively, and the horizontal correction angles are 0.82° and 3.45°, respectively. The dominant frequencies of longitudinal and lateral car-body vibrations for both systems are within 10 Hz, while those of vertical car-body vibration are within 40 Hz for the Shanghai maglev system and within 30 Hz for the Changsha maglev system. The sampling frequency meets the detection requirements. For the Shanghai maglev system, the maximum ISO 2631-1:1997 weighted acceleration is 0.9 m·s^-2, with exceedance ratios of 95.5% for level Ⅰ and 71.1% for level Ⅱ. The maximum Sperling ride-comfort indexes for lateral and vertical directions are 2.64 and 2.73, with level Ⅰ exceedance ratios of 0.96% and 69.8% respectively. The maximum A-weighted sound level is 73.8 dB(A), and the ratio exceeding 70 dB(A) is approximately 78.2%, indicating that the running quality of the vehicles in the Shanghai maglev system is good. For the Changsha maglev system, the maximum ISO 2631-1:1997 weighted acceleration, Sperling indexes for the lateral and vertical directions are 0.26 m·s^-2, 2.32, and 2.15, respectively, all below the level Ⅰ limits, which indicates that the running quality of maglev vehicles in the Changsha maglev system is excellent. Visualizing various evaluation indicators in the longitude-latitude coordinate system of the maglev line intuitively reflects the along line distribution of the maglev vehicles' running quality. This method can provide data support for the maglev track operation and maintenance department to precisely regulate the service status of maglev tracks at different mileage locations.