Study On Vibration Behavior Of Carbody Underframe Suspended Systems For High Speed Trains

With the rapid development of the national economy,the communications between cities are more frequent.While the traditional railway has been lagged behind the development of society and technology,the opening of the high-speed railway has met the need of the people for fast,safe and comfortable travels,and the high speed railway has become the main artery for China’s economic development.The carbody light-weigh design criterion and the power-disperse type of traction have solved the bottleneck of restricting the increase of vehicle running speed.Compared with the traditional steel carbody structure,the weight can be reducerd about 30% with the new type of aluminium alloy structure.And the power-disperse type of traction can distribute the traction power to different cars and reduce the axle load of motor cars,which is very important for improving the vehicle running speed.However,the new challenge for vehicle system dynamic performance has been brought up.The light-weight design reduces the stiffness of the carbody and further causes carbody elastic vibration.After the application of the power-disperse type of traction,the traction transformer,bracking element and other suspended equipment,whose weight maybe ten tons,are attached on the carbody underframe,which may make the carbody flexible vibration more aggravated and seriously affect the riding quality of the vehicle.In view of this,the carbody underneath suspended system of high-speed train is studied as the object,and the main purpose is to reduce the carbdy elastic vibration and maintain the vibration of the equipment at a reasonable range.The coupling vibration behavior of the carbody and suspended equipment is studied.Then the following works have been carried out in this thesis:(1)Based on the carbody modal test and vehicle dynamic test on roller test rig,the analytical and simulation models of rigid-flexible coupled dynamics with considering carbody elasticity and suspended equip ment are built.And the optimum suspension parameters of suspension equipment are deduced.In order to study the effect of longitudinal impact on the elastic vibration of carbody,the longitudinal motions of wheelset and bogie frame are considered in the analytical model.What’s more,the nonlinear characteristic of anti-yaw damper and airspring is considered in the simulation model.At last,the accuracy of the rigid-flexible coupling dynamic model is verified by roller rig test.(2)Based on the rigid-flexible coupling dynamic simulation model of vehicle system,the influence of the suspended location and parameters,and the primary and secondary suspension parameters,on the coupled vibration behavior of carbody and suspended equipment is studied,which provides the basis for the vehicle suspension parameter design.Based on the high-speed train line tracing test,the coupling vibration problem of carbody elastic vibration with bogie lateral instability is analyzed.The influence of lateral suspended parameter is studied which provides some advice for the selection of lateral parameter.(3)The coupled vibration behavior of carbody and suspended system under external excitation is studied,including the dynamic unbalance of suspended rotating equipment,unsteady stochastic aerodynamic load and track stochastic irregularity,which can provide the basis for improving vehicle suspension system under operation adaptability(4)The semi-active suspension models for carbody suspended systems with skyhook control strategy and LQR control strategy are estabilished.The effects of semi-active control on carbody vibration reduction are compared and analyzed,which indicates that the semi-active control can reduce carbody elastic vibration obviously.The control effect di ffers with different control strategy.It can provide theoretical support for further reducing the elastic vibration of carbody and improving the riding comfort of passengers.(5)Based on the nonlinear coupling buffer model,the high-speed train model of rigid-flexible coupling dynamics is established.The coupled vibration behavior of carbody and suspended equipment under longitudinal impacts in the conditions of traction and braking,and train to train rescue,is studied,which provides the basis for the design of the longitudinal suspension parameter s of carbody underneath suspended system.