Dynamic Performance And Polygonai Effect Of Elastic Wheel On Railway Vehicles

As an emerging vehicle,urban rail transit has the advantages of large passenger capacity,fast speed,green environmental protection and low average cost,which greatly alleviates the urban roads pressure and provides convenience for people to travel safely.However,with the capacity increases,as well as application of new materials and new technology,the friction increasingly complex between wheel-rail operation condition,there are many problems in the wheel/rail transportation system,such as rail fracture,wheel irregularity,rail corrugation,and so on,which greatly shorten the service life of the wheel-rail transportation system and affect people’s travel safety.The research on wheel-rail coupling contact is the foundation to solve problems of urban rail transit system and plays an important role in the development of urban rail transit.Based on Hertz contact theory and dynamics method,the wheel-rail wear is studied.The main study is as follows:This study investigates the wheel-rail coupling vibration(WRCV)of an urban railway system.By considering replacing an originally rigid wheel with an elastic wheel,an new dynamic model of railway vehicles with elastic wheels is established.The bouncing,pitching and rolling motions of the system are taken into account.When the track is irregular,the influence of stiffness coefficient of elastic wheel on vertical vibration is studied.The time-domain responses under three given power density spectral functions are obtained using the dynamic model and the relationship between the vertical acceleration of the wheel and the track irregularity is also obtained.For the case of the same track irregularity,the relationship between the stiffness coefficient of the elastic wheel and its vertical acceleration is studied.The numerical results show that the fluctuation of wheel acceleration reduces with a decrease in track irregularity,and follow nonlinear changes with an increase of stiffness coefficient of elastic wheel.In this study,base on bilinear,multilinear and nonlinear plastic strain models,the applicability of four typical wear models as Archard,Pearce,Usfd and Braghin are studied.Instantaneous wear of all wear models is calculated in a contact area.Equivalent wear coefficient is used to quantitatively express the proportional relationship between wear models.The uniform expression of wear models are derived analytically.The instantaneous wear rate of different wear models is evaluated under harmonic excitation.The instantaneous wear rate fluctuation of different wear models is calculated under harmonic excitation,and the influence of speed on the wear fluctuation is studied.The results show that four wear models have similar ability in calculating instantaneous wear,the frequency characteristics of excitation can be accurately reflected in general sense,and the fluctuation law is almost same.When adapting to the plastic model,the adaptability of wear model and bilinear plastic model is poor,the wear model can be well combined with the multi-linear and nonlinear plastic models.Speed has a significant effect on the frequency and amplitude of wear fluctuation,the wear model can better adapt to the plastic model at high speed.Finally,based on the wheel wear and the existing defects of the wheel,the structure is optimized,and the new elastic wheel is designed to reduce the vibration of the train and the polygon wear,which extend the service life and reliability of the wheel,and ensure the safe operation of train.