Study On Characteristics Of Structural Vibration On Two-stage Vibration Isolation System Of Power Assembly

DMU,a kind of passenger trains,enjoys a proper place in the field of high-speed railway transportation.Compared with the EMU,DMU is relatively well-adapted in some undeveloped regions including some Asian countries and remote areas in China.Considering the advantages of electricity-free and convenience,DMU are widely used in those places mentioned above where the electric grids can be hardly accessible.The internal combustion powertrain system has the characteristics of multi-source excitation,wide frequency domain,and complex coupling.In order to control the vibration of the double-layer vibration isolation system,reduce the reaction force,and improve the comfort,the double-layer vibration isolation design is usually adopted.In the traditional double-layer vibration isolation design,the parameters are optimized based on the multi-body dynamic model,and Ignoring the influence of the structural vibration caused by the diesel generating set's flexibility.This paper aims to quantitatively analyze the vibration characteristics effect of powertrain double-layer vibration isolation system by set's structural vibration,study the influencing factors of the structural vibration control,summarize the effective strategies of control,and verify the strategies effectiveness through the powertrain experiment bench.First,based on the test data of two kinds of internal combustion power assembly,analyzing the structural vibration proportion of the main components and the dynamic reverse force transferred to the body quantitatively of the powertrain.Analysis to get the main modal information of the unit's structure vibration.With the joint simulation of Hypermesh and ANSYS,the finite element model of the frame and the unit was established.Based on the finite element model,the dynamics model of rigid-flexible coupling system considering the structural vibration of unit and frame was established by Adams.Through the simulation calculation,the influence of unit structural vibration on the inherent characteristics and response characteristics of the system was compared and analyzed.The effects of adjusting vibration isolator parameters,changing the flexibility of the unit and the frame,and adding dampers between the units are studied.The effective strategies for controlling structural vibration are summarized.Finally,utilizing powertrain experimental bench to verify the effectiveness of structural vibration controlling method.The research results show that the structural vibration of the unit will cause the vibration intensity of the unit to become significantly larger under the operating conditions,which will cause the magnitude of the dynamic reaction force transmitted to the vehicle body to become larger.Adjusting the stiffness of the frame and the unit can change the modal characteristics,and it has a positive effect on controlling the structural vibration by appropriately reducing the stiffness of the frame and increasing the rigidity of the connecting sleeve of unit.By reducing the stiffness of the vibration isolator,and increasing the damping of the dampers in specific frequency bands can effectively control the adverse effects to powertrain's vibration characteristics caused by the structural vibration of the unit.