Study On Car Body Vibration Reduction For High-Speed Trains Based On Intellectual Structures

With the rapid development of high speed railway technologies, the enhancement of running performance and ride comfort for passenger cars is unceasingly required. The ride performance is closely related with the elastic vibration of car body. Meanwhile, the car body lightening of high-speed train causes the elastic vibration problem of car body, which inevitably reduces the ride comfort for passengers. In order to solve this problem, a lot of theoretical and experimental researches have been carried out for the car body home and abroad, including the constrained damping processing, variable stiffness structure, passive and active vibration control, etc. However, we still need to explore continually to acquire the solution which can be applied to the actual vehicle. Previous studies indicate that the active control based on piezoelectric smart structure is an efficient way for car body elastic vibration reduction.Through summarizing the existing researches and using the method of being from simple to complexity, the algebraic relation between output torque and control voltage of the π piezoelectric pile actuators is derived. The active vibration control law based on piezoelectric intellectual structures is obtained by using the cantilever beam test model. Then, the vertical dynamic model of high-speed vehicle with considering the car body elastic effect and piezoelectric actuator is established. The match relations between car body structure frequencies and bogie frame vibration frequencies are studied. Finally, the active control simulation of vehicle elastic vibration is realized based on the independent modal shape control.By studying the structural strains under the effect of each mode, it is known that the piezoelectric actuators should be installed in the maximum strain points of the structures, i.e., the root of the cantilever beam and the mid of the vehicle. The features of vibration control of piezoelectric cantilever beam and the control effects by changing parameters are analyzed by the method of LQR, It indicates that the elastic vibration of the cantilever beam can be controlled effectively by adopting active control. The smaller the R is, the greater the control force, as well as the energy consumption. The greater the Q is, the faster the amplitude of vibration decays.The determination of Q and R values is related to the performance function and controlled output force. The eigenfrequencies of car body and bogie frame are discussed and the elastic vibration performance of car body with and without active control is compared. It is known that in order to restrain the elastic vibration of car body in the case of none control, the first bending vibration frequency of car body should be greater than2^1/2 times of bogie vertical vibration frequency. And also the choose of car body bending frequency should consider the bogie frame structure frequency. The application of the active control based on piezoelectric actuators can effectively restrain the first vertical bending vibration of car body with no effect on the rigid vibration, and the ride performance and accelerations are improved markedly. When R is equal to1x10-6, the output force of actuators is reasonable and the optimal control effect can be obtained.