Modeling And Analysis Of Nonlinear Dynamic Characteristics Of Suspension System Of Air Compressor For High-speed Train

As we all know, High speed trains,including subway, intercity rail, motor car and high-speed rail, greatly facilitate our daily life. However, the trains can not run regularly,efficiently and quickly without air compressor moving normally, which is one important parts of high speed trains and is often hung under the bogie of the trains. Air compressor of high-speed trains is the main device for the train to provide compressed air, which is a prerequisite for the normal operation of the train braking and other pneumatic components normal operation, and is related to operating efficiency and condition of the train brakes. To better understand the vibration damping characteristics and influencing factors of air compressor systems and to improve the reliability of high-speed trains compressor,dynamics of high-speed operation of the air compressor suspension damping control system is necessary.In this paper, the author establishes a 3 DOF nonlinear vibration model to simulate the vibration characteristics of air compressor. The negative stiffness mechanism is proposed to attenuation the vibration and improve the stability of air compressor. To analyze nonlinear response and influences of parameter variation of the system with deterministic excitation,the bifurcation diagram and Poincare section with phase diagram and the Floquet multiplier level are obtained numerically. PSD, RMS, the time domain curves and the mean curve are obtained to investigate the damping effect and the influences of parameter variation of the system with random excitation. The main works and conclusions include the following:1. The paper gets suspension system of air compressor basing on a new type negative stiffness mechanism and passive control strategy, and then derives the parametric dynamic equation according to the second category Lagrange's equations.2. The proposed nonlinear dynamic model is solved using Runge-Kutta integration method based on MATLAB software. Periodic motion, bifurcation and roads to chaos of the system are investigated and illustrated by using the bifurcation diagram map, poincaresection and phase portrait. Finally, the influence of excitation frequency on the stability,occurrence of chaotic motion and other nonlinear phenomena are investigated quantitatively.It provides the basis for the stability control of air compressor. Furthermore, the Floquet multiplier level is obtained by solving the perturbation equation with original equation applying by numerical method, which can be used to explore the global the global stability of the vibration damping system.3. In chapter 4, a realistic case, air compressor excited with random noise, is considered in order to explore the stochastic response of the system with random excitation.The stochastic differential equations are derived applying Itó formula and Taylor expansion.The attenuation effect related to system parameters is also detected by solving stochastic differential equations with numerical method.The results indicate that variation of stiffness and excitation frequency has a large influence on the nonlinear response of the system, and the amplitude of excitation may reduce unbounded motion in the resonance region. The model gets the best damping performance in the 10-100 Hz frequency region.