Research On The Cause Of Polygon Of Rail Transit Wheel

With its characteristics of large volume,fast speed,safety and comfort,high punctuality rate,rail vehicles have gradually become an important means of transportation for people to travel.However,after the wheels of rail vehicles run for a long time,the polygon effect will often cause a series of changes in the dynamic response of the vehicle-track system,and the vibration response of the vehicle and track will also become more intense,which will cause the degradation of the vehicle dynamic performance,cause the wheel and track intense noise,and then affect the ride comfort and drive stability.Seriously,it will cause damage to the important parts of the vehicle,and even endanger driving safety.The research on the origin of wheel polygon is the basis to solve the running quality and safety of the vehicle,and it plays a crucial role in the sustainable development of rail vehicles.This paper focuses on the wheel polygon caused by wheel vibration and wheel-rail contact force.The specific work is as follows:Firstly,a dynamic model which can clearly analyze the force and acceleration of each component inside the wheel is established.Based on the analysis of the model in time domain and frequency domain,combined with the vibration acceleration of the wheel system and the carriage system,the inhibitory effect of resilient wheels on the wheel polygon caused by wheel vibration under different working conditions was studied.The results show that in terms of vibration acceleration of the wheel system,the resilient wheel has rubber components,so the vertical vibration in the frequency range of 70-150 Hz and the lateral vibration in the frequency range of 30-150 Hz are significantly reduced compared with the rigid wheel.At the same time,due to the existence of rubber components,the axial stiffness of the resilient wheel is smaller than the radial stiffness,so the decoupling frequency of the transverse vibration of the resilient wheel is lower than that of the rigid wheel.On the basis of an analysis of the train system vibration acceleration,although the flexible rubber components produced within the elastic vibration will lead to the results of the vertical vibration of car and rigid wheels,the same results of transverse vibration is greater than the rigid wheels,but the frequency of resilient wheels won’t affect the car system vibration acceleration and can well restrain carriages in 50-150 Hz vertical and horizontal vibration.Secondly,based on the established vehicle system dynamics model,the restraining effect of resilient wheels on wheel polygons caused by wheel-rail contact forces under different working conditions is studied.The results show that the single wheel and wheelset system of resilient wheel can effectively reduce the vertical wheel-rail contact force during vehicle operation.In the process of wheel rolling,the resilient wheel can reduce the unsprung mass within a certain frequency range,which can effectively reduce the interaction force between wheel and rail and inhibit the generation of constant wavelength wave grinding.Under the same polygon order,the resilient wheel needs more vertical and transverse wheel and rail forces,so it can be concluded that the resilient wheel has inhibitory effect on the generation of polygons.And then,the contact behavior of the wheel in the rolling process was studied deeply for the existing resilient wheels with composite rubber components.Based on the wheel-rail coupling finite element model,the variation law of contact spot at rest and at different speeds is obtained,and the characteristics of wheel-rail contact stress and maximum equivalent stress,as well as the variation law of friction dissipated energy and strain energy are given.The results show that the shape of the contact spot of the resilient wheel is obviously different from that of the rigid wheel at different vehicle speeds.The rubber element can absorb the contact stress of the wheel and rail,so the contact stress of the resilient wheel is obviously less than that of the rigid wheel.Since the rubber element absorbs energy through large deformation when the wheel is rolling,the friction energy dissipation of the resilient wheel is less than that of the rigid wheel,and the strain energy of the resilient wheel is greater than that of the rigid wheel.Finally,based on the above study of resilient wheels can well solve the wheel vibration and wheel/rail contact force polygon effect,as a result of this conclusion,according to the present the most widely used a V-shaped structure resilient wheels,designed a kind of is simple and easy for K type rubber components and remove anti failure wheels and a nested type rubber components and dual pressure ring against the failure of the wheel,It can inhibit the wheel polygon and improve the running quality and safety of vehicles.