Vehicle-Guideway Dynamic Interaction Of The EMS Low Speed Maglev Vehicle

Vehicle-guideway interaction vibration greatly influences the system price and ride comfort. It is an important problem that must be settled in the commercial process of the EMS low speed maglev transportation system. From simplicity to complexity, this dissertation simplifies the maglev system and levitation guideway into different formats, studies system stability and response of nonlinear dynamics and structure dynamics by respectively analyzing maglev system and levitation guideway based on the recent results of the track transportation system. It aims at exploiting the rules of vehicle-guideway interaction theoretically and finding the methods to suppress the oscillation, and helps to design the levitation controller and guideway structure.The effect of the time delay in position and speed feedback signal to the stability of the maglev system with rigid guideway is considered. The relationship between control parameters and system natural frequency, critical time delay are obtained. It shows that the maglev system have several natural frequencies. The stability conditions of the system are obtained based on characteristic root method. The Hopf bifurcation direction and stability of the system at the critical point are also investigated. Then the elasticity of the guideway is considered, its deflection is simplified as known cosine wave.Center manifold reduction and Poincarénormal form theory are employed in this paper. The nonlinear oscillation with the proportion between disturbance and natural frequency to be of 1:1, 1:3, 3:1 and none of the above are investigated based on the method of Multiple Scale. Singularity, bifurcation and chaos etc. are found in the system response. It is shown that time delay can control the existence of the complicated dynamic behavior. The trend of the control parameters to weaken the dynamic response is given too.To approach the real system more, the sleeper is simplified as evenly distributed elastic foundation. The analytical model of smooth and straight concrete guideway is constructed. Simplifying the maglev vehicle to an evenly distributed force, the closed form solution of the guideway is deduced based on mode superposition method. It is pointed out that beacuse the first natural frequency is much smaller than the second one, it bears the primary function in vehicle guideway interaction. The relationship between natural frequency and structure parameters are acquired. Guideway deflection influenced by the running speed of the load is also discussed.The maglev train is simplified as a series of evenly distributed force. Resonant and cancellation phonomenon are found when we analyze the closed form solutions of the guideway. The resonant and cancellation speed are deduced. They indicate that the displacement of the guideway will increase when the maglev train runs at resonant speed and decrease when it runs at cancellation speed. The resonant speed should be avoided. The investigation about the ratio of span to the length of the vehicle shows that the smaller the ratio is, the larger the dynamic impact of the guideway will become. Properly selecting the ratio can suppress the vehicle-guideway structure interaction.At last, the vehicle-guideway dynamic model is built. We use numerical simulation method to analyze the variation of characteristic roots of the linearized system. The effect of the control delay to the vehicle-guideway interaction is also discussed. Finally, a few conclusions presented in the article are testified by the experiments.