Lateral vibration characteristics of low- to medium-speed maglev train–track–bridge coupled system in an accelerated state: Experimental and theoretical investigation

Improving the running speed of in-service commercial low- to medium-speed (LMS) maglev transit systems is the most cost-effective way to enhance their capacities. However, an increase in speed above 100 km/h disturbs the lateral guidance performance of the LMS maglev train and the lateral vibration performance of the train–track–bridge system. To explore the coupled lateral vibration of an accelerated LMS maglev train–track–bridge system, a field test of the Changsha maglev commercial express was carried out at various speeds and the resulting lateral responses of the car body, levitation frame, track sleeper, bridge girder, and bridge pier were analysed. Next, a refined theoretical model of the maglev train–track–bridge coupled vibration system was established and verified using the experimental results. This model was subsequently applied to explore the lateral vibration characteristics of the system and their underlying mechanisms at maglev running speeds up to 160 km/h. The results indicate that the lateral responses of the levitation frame and car body clearly increased when the running speed exceeded 120 km/h, and that the lateral vibrations of the sleeper were significantly larger than those of the girder. Vertical irregularities were shown to affect the lateral guidance force, confirming the presence of a coupling phenomenon; thus, appropriate control of the vertical track irregularity amplitude can actively reduce the lateral dynamic responses of the coupled system. The results of this study indicate that although the dynamic responses of the maglev–track–bridge system increase with speed, the steady guidance of an LMS maglev train can still be ensured at running speeds up to 160 km/h.