Dynamics Analysis Of The Abnormal Vibration For A Certain Subway Bogie

In recent years,as China’s urban population continues to increase,in order to meet people’s travel needs and to get people to their destinations conveniently,quickly,and safely,it is necessary to develop urban transport vehicles which is simple,tolerable,and have large carrying capacity.Urban rail transit provides a solution to this problem.Since the construction of the first subway in China,after decades of development,China’s subway technology has become increasingly mature,more and more cities have opened subways,and the mileage of subway operations has also continued to increase.Due to the long-term high-load operation of subway vehicles,the working environment of subway bogies is relatively poor,and they are suffering a lot of acting force,so some problems sometimes occur.This thesis takes a domestic B-type subway as the research object,and analyzes the reasons for the abnormal noise of the bogie,the breakage of the adjustment rod of air spring height valve,and the breakage of the first spring fastening bolt.This thesis only considers from the perspective of vehicle system dynamics,tries to find out the cause of the problem from the direction of vehicle abnormal vibration.Analysis of the structure feature of the bogie,establish a dynamic model according to the specific parameters of the vehicle.Analyze the dynamic performance of the subway vehicle under normal operating conditions,as well as the vibration characteristics of the car body,bogie frame and other components.The results are used as the benchmark for dynamic performance comparison,and compared with the dynamic performance of the vehicle under the conditions of wheel polygon,wheel tread worn,component failure,curve line and track twist irregularity,etc.To estimate the relationship between the vibration of the vehicle and components and the force of the component and the above different influencing factors.And analyze the reasons that may cause the vehicle bogie abnormal noise and component breakage.The main work and conclusions of this thesis are as follows:(1)Using the dynamic response of the vehicle when the components are not failed as a benchmark,compared with the situation after the failure of the air spring and the failure of the secondary lateral damper.It is found that the air spring failure will affect the vertical performance of the vehicle and deteriorate the vertical performance of the vehicle,the failure of the secondary lateral damper will deteriorate the lateral performance of the vehicle.Both of them will cause abnormal vibration of the vehicle,and may cause abnormal sound of the bogie of the vehicle and the components fracture.Therefore,in order to avoid a more adverse impact on the vehicle,when a component fails,it should be repaired and replaced in time.(2)Taking the vehicle’s dynamic performance of normal condition as the benchmark,and compared with the dynamic response of the vehicle system when three,four,eight and nine order wheel polygon and the wheel tread worn exist in the car.The results show that when the wheels polygon exists in the car,the vertical vibration of the car body,the bogie,the axle box and the adjusting rod will become severe,and the vertical maximum vibration acceleration will obviously increase with the increase of the wave depth of polygon.The vibration of the car body is greatly attenuated by the suspension system.But for the axle box and the frame,as the wave depth increases,the impact continues to increase,and the vibration amplitude caused by the wheel polygon also continues to increase,greatly exceeding the vibration amplitude when the wheels are normal,the vertical vibration acceleration increases rapidly,and the larger the orders of wheel polygon,the more obvious the change,which has a great impact on the axle box and the frame,will cause the bogie abnormal noise and the breakage of fastening bolt at bottom of axle box.The wheel tread worn will deteriorate the lateral performance of the vehicle,and the acceleration of the vehicle’s lateral vibration will increase.This is also the reason for the abnormal vibration of the vehicle,which will cause the abnormal sound of the bogie and the components fracture.(3)The stability,safety and vibration acceleration of the vehicle under different curve parameters are calculated.The calculation results show that the larger of the radius and the longer of the transition curve,the smaller the lateral vibration of the car body,frame,axle box and adjusting rod,and the better the vehicle’s safety.The running speed also has a great influence on the performance of the vehicle,therefore,in order to make the vehicle pass the curve line safely and smoothly,and avoid the discomfort of the people in the vehicle,the running speed should be reduced.By analyzing the influence of curve superelevation on vehicles,it is found that the greater the deficient superelevation or surplus superelevation,the greater the lateral force on the vehicle,which resulting in the deterioration of the vehicle’s lateral performance and the low safety of the vehicle.The running speed of the vehicle should be as close as possible to the equilibrium speed of the line design to avoid accidents such as the breakage of fastening bolt at bottom of axle box and the adjust rod due to the large lateral force of the vehicle.(4)The dynamic performance of the vehicle when passes through the twist of track is analysis,and the dynamic performance of the vehicle under different amplitudes is compared.The results show that when the vehicle passes through the twist of track,car body,frame,axle box and adjust rod will have a large lateral and vertical vibration acceleration,and the vibration acceleration increases with the increase of amplitude.It may cause the accident of bogie abnormal noise and fastening bolt breakage.And the vehicle will have a large wheel unloading rate and derailment coefficient when passes through the twist of track,and the value of them will increase rapidly with the increase of the amplitude,affecting driving safety.