Study on the Vibration Characteristics of Suspension Frame System for Maglev Train Under Track Irregularity Harmonic Excitation

In order to avoid the abnormal vibration behavior of the high-temperature superconducting (HTS) flux-pinned magnetic levitation (maglev) train at high velocity (reach up to more than 500 km/h) due to the external interference from the suspension frame system, the vibration characteristics of suspension frame system are studied. First, the levitation force between the HTS combination and the permanent magnet guideway (PMG) is measured by way of the quasi-static test platform, and the empirical formula of levitation force is obtained. Then, the nonlinear vibration differential equation of the suspension frame system under the track irregularity harmonic excitation is established. The first approximate solution is obtained based on the multiscale method, which is verified by way of the numerical solution. Finally, the amplitude-frequency response equation of the suspension frame system under the primary resonance is derived; thus, the influence of running velocity, track irregularity wavelength, and amplitude on the steady-state amplitude is studied. An analytical method for determining the feasible domain of track irregularity parameters under different running velocity is proposed based on the safety standard of the maglev train. The effective domain of track irregularity parameters can be obtained. The methodology and results of this article provide a theoretical foundation for constructing PMG of the HTS flux-pinned maglev train.