Study On The Influence Of Bogie Suspension Parameter On The Flexible Carbody Vibration

With the development of rail transit technology,the speed of vehicles is getting faster and faster,resulting in serious impact between wheel and rail.Wheel and rail wear is also becoming fearful.Reducing the impact between wheel and rail has become a concern of many scholars.An effective way to reduce the impact between the wheel and rail is to reduce the vehicle's weight,so car body has become one of the many members who needs to reduce weight.At the same time,with the application of aluminum alloy and a large number of light materials on the vehicle body,the vehicle's weight is getting smaller and smaller,Although the strength of the car body is enough,the rigidity of the car body is reduced.As a result,the natural vibration frequency of the vehicle body is reduced,in particular,the first-order bending frequency of the vehicle body is reduced,which easily causes the vehicle body to resonate with other components,thereby affecting the running stability and ride comfort of the vehicle.The International Railway Union and some countries with developed rail transit have proposed limiting the rigidity and the natural frequency of the car body,so that the natural frequency of the car body can be sufficiently separated from the vibration frequency of other parts of the vehicle.China has also imposed homothetic constraints on the stiffness and bending frequency of the car body,mainly GB/T33194-2016 and <200km/h speed class vehicle strength design and test >identification The Provisional Regulations stipulate that the first-order bending frequency of the vehicle body is greater than 10 Hz,and the first-order bending frequency of the vehicle body and the pitch and bounce frequency ratio of the bogie are greater than 1.4.Why is there a difference between China's standards and the standards of the International Railway Union and some rail transit developed countries? Therefore,it is of great significance to carry out the impact of the suspension frequency of the bogie on the natural vibration of the vehicle body.This paper first compares the requirements of the stiffness and natural frequency of the car body in the world standards,and analyzes the difference.The research overview of the elastic vibration and rigid-flexible coupling dynamics theory of the vehicle body is summarized.The vertical coupling model of the vehicle is established,and the simplified formula of the pitch and bounce frequency of the bogie is derived.The finite element model of the vehicle body is established in HyperMesh.The substructure analysis of the car body is reduced by ANSYS.The analysis result is introduced into the multi-body dynamics software SIMPACK to establish the rigid-flexible coupled dynamics model of the flexible car body.With the established model,the effects of suspension stiffness and suspension damping on vehicle body vibration and bogie vibration are studied.The first-order bending frequency of different vehicle bodies and the vibration of the vehicle body and the vibration of the bogie are analyzed.The following main conclusions are drawn:1)In certain range,reducing the suspension stiffness of a series can improve the running stability of the vehicle,provide a better working environment for the bogie,and also reduce the pitch and bounce frequency of the bogie,so that the frequency of the bogie and the vehicle body are sufficiently separated.In the design of the vehicle,the vertical stiffness of the suspension should be appropriately reduced.2)In certain range,reducing the vertical stiffness of the secondary suspension can improve the stability of the vehicle and reduce the bounce frequency of the bogie.However,the reduction of the vertical stiffness of the secondary suspension increases the dynamic deflection of the secondary suspension and deteriorates the vehicle suspension space.The secondary suspension stiffness mainly affects the low frequency vibration of the vehicle body and the high frequency vibration of the bogie.Therefore,the vertical stiffness of the secondary system in the vehicle design mainly satisfies the result without interference.3)In certain range,increasing the vertical damping of a series of suspensions is beneficial to improve the running stability and improve the working condition of the bogie and reduce the bounce frequency of the bogie.However,the energy transmitted to the vehicle body by the bogie is increased.4)In certain range,reducing the vertical damping of the secondary suspension is beneficial to improve the stability of the vehicle,improve the isolation capability of the vehicle's high-frequency vibration,and reduce the bounce frequency of the bogie.However,it will deteriorate the working environment of the bogie and reduce the suppression ability of the low frequency vibration of the vehicle body.5)Reducing the degree of separation between the first-order bending frequency of the car body and the pitch and bounce frequency of the bogie will deteriorate the running stability of the car body and the working environment of the bogie,and also increase the amplitude of the car body vibration.However,choosing a suitable suspension damping ratio can improve the smoothness of the operation.Therefore,the first-order bending frequency of the vehicle body is greater than 10 Hz and the first-order bending frequency of the vehicle body with the bogie pitch and bounce frequency ratio greater than 1.4 is somewhat conservative.