Research On Theory And Application Of Broadband Vibration Reduction Of Urban Rail Composite Vibration Absorber

As a multi-degree-of-freedom dynamic system,the wheel-rail vibration is intensified due to the excitation caused by the irregularity of the track system during the driving process of urban rail transit vehicles,which leads to the generation of low-frequency vibration.Its transmission path is transmitted from the primary suspension to the bogie and then to the trailer body through the secondary suspension.On the other hand,the generation of vibration causes some energy to be unable to be absorbed and directly transmitted into the carriage,further reducing the stability of the vehicle operation and causing adverse effects on the comfort of passengers riding the vehicle.In view of this,the dynamic vibration absorber,as one of the mechanical devices that can effectively suppress the vibration of the carbody,has become the main research object of this topic.Its vibration damping performance and practical application have been widely concerned.This article focuses on the elastic vibration system of urban rail vehicle traffic,and aims to improve the multi-band vibration of the multi-degree-of-freedom system.Starting from the basic theory of single-degree-of-freedom dynamic shock absorbers,and combining the mechanical characteristics of magnetorheological elastic materials with the characteristics of two design frequencies of composite shock absorbers,the elastic carbody model including magnetorheological shock absorbers and composite shock absorbers was thoroughly studied.The results show:(1)Based on the dynamic model of the elastic body of urban rail vehicles with magnetorheological shock absorbers,considering the impact of the vehicle’s running process on the carbody and combining the dynamic characteristics of the magnetorheological elastomer,a design method of a magnetorheological damper for the existence of a dual-band vibration reduction target has been proposed.With the optimization of stiffness as the goal,the optimal design frequency is fitted by multiple linear regression to make the vibration absorber and the carbody always resonate,which ensures the vibration reduction performance of the vibration absorber to the greatest extent.The results show that the magnetorheological shock absorber can be better applied to urban rail vehicles,and achieves the suppression effect on the rigid frequency band of the elastic carbody and the higher frequency band of the elastic frequency band.(2)Using the orthogonality of the modalities,a vertical dynamic coupling model of the vehicle-rail-composite vibration absorber considering the elasticity of the carbody is established.Combining the characteristics of floating and nodding vibration in the low frequency band of the carbody,the rigidity and elastic vibration in the low frequency band and the middle and high frequency bands,the characteristics of the dual vibrator structure of the composite vibration absorber are used to design the parameters of the composite vibration absorber to achieve the control of multiple peaks in the target frequency band by the composite shock absorber.The results show that the installation of the composite shock absorber has a good damping effect on the low frequency band and the middle and high frequency band of the carbody,which is conducive to the improvement of the running quality of the vehicle.This work provides a certain reference value for the research and application of using composite shock absorbers to reduce the vertical vibration of vehicles.(3)Starting from the vehicle-rail coupling model,aiming at reducing the rigid vibration and elastic vibration of the carbody,the vehicle-rail coupling vertical model including the magnetorheological composite vibration absorber is established,and the design method of the magnetorheological composite dynamic vibration absorber suitable for urban rail vehicles is proposed,so as to improve the vibration reduction effect of the traditional dynamic vibration absorber;The expression of the optimum design frequency in multi-frequency band is fitted by multiple regression analysis method to give full play to the damping effect of magnetorheological vibration absorber.The influence of magnetorheological dynamic vibration absorber with optimized stiffness on the vertical vibration damping characteristics of the carbody is studied,and the structure of magnetorheological composite dynamic vibration absorber is further designed.The results show that dynamic vibration absorber can obviously inhibit the wide-band vibration of the carbody,and the proposal of mechanical structure provides theoretical guidance for the application of composite dynamic vibration absorber.