| ABSTRACT:Railway transportation plays an important role in social economy. It is a general trend to develop high-speed railway in recent years. With the increase of the train speed, vibrations of vehicle increase sharply. Riding stability, comfort and road safety become worse gradually. The higher speed that causes the more prominent dynamics and vibration problems, the more serious security will be. So, the study of high speed vehicle's dynamic behaviors, vibration control and time delay to restrain vibration, in particular, to restrain the lateral vibration is extremely necessary.This dissertation deals with building high-speed locomotive model and dynamic analysis based on magnetorheological damper, studying semi-active control strategy and time delay in control system. The main work and innovative contributions of this dissertation are as follows.(1) On the basis of analyzing dynamic characteristics of magnetorheological damper, it is proposed that magnetorheological dampers can be applied to high-speed locomotive as anti-snake shock absorber and the secondary lateral damper.17degrees of freedom lateral semi-active control model and21degrees of freedom lateral semi-active control model of high-speed whole locomotive with MR dampers are established. Simulation analysis is performed to verify that the magnetorheological damper is applied to high-speed locomotive is feasible.(2) After analyzing and comparing passive control, semi-active on-off control, and general fuzzy control strategy, a self-adapt fuzzy control strategy is put forward. The simulations are performed for the different control strategy to the high-speed locomotive lateral dynamic model based on magnetorheolotical damper. The simulation results show that the self-adapt fuzzy control strategy can lower the lateral vibration of the locomotive effectively, restrain snaking motion, and improve the riding comfort obviously than others.(3) The critical velocity of high-speed locomotive system is solved. The limit-loop and bifurcation is analyzed under critical state which verifies self-adapt fuzzy control strategy's validity. The first-order approximate solution of magnetorheolotical damper control system is obtained by the averaging method. According to singularity theory, the hysteretic integration and double limit integration of system are studied. And the effects of system parameters on amplitude frequency curve and stability are analyzed in detail. (4) The lateral dynamic action of locomotive system is studied. Effects of structure parameters and suspension parameters on lateral dynamic are investigated. Much of design requirements are put forward to reduce the lateral dynamic and enhance riding stability. According to the analyzed result, some advice to optimize parameters of locomotive system is given.(5) Theoretical studies and simulation are included about dynamic characteristics of the quarter and whole locomotive dynamic system based on magnetorheological damper with time delay. Through the method of multi-scale, the primary resonance of magnetorheological damper control system is analyzed in detail. The effects of system parameters on amplitude frequency curve and system stability are investigated. |
