| With the improvement of the operation speed of China’s high-speed railways and the increasing mileage of operations,the wheel/rail short wave diseases are gradually exposed,such as wheel polygon wear,rail corrugation and welding surface irregularities.The medium and high frequency vibrations caused by them not only increase the railway maintenance cost,but also pose a potential hazard to the safety of train operation.We often need realistic modeling methods and effective simulation software to eliminate or reduce these diseases.The current vehicle/track system dynamics software still needs to be improved in the openness,reusability,scalability and maintainability.The ability of vehicle/track system dynamics model to handle the high-speed rotating characteristics of the flexible wheelset also needs to be improved.Therefore,it is necessary to carry out the research on the dynamics of the vehicle/track coupling system considering the high-speed rotating characteristics of the flexible wheelset,and develop the rigid-flexible coupling dynamics software of vehicle/track system with good software architecture design,openness,scalability and maintainability.It is used to explore the high-frequency interaction between wheel and rail of high-speed vehicle/track system and the dynamic response under the condition of wheel/rail damage.It can provide the theoretical basis for the maintenance.Based on the finite element and multi-body dynamics theory,combined with the wheel/rail three-dimensional geometry relationship and the wheel/rail contact force calculation method,the vehicle/track rigid-flexible coupled multi-body dynamics model is established.Combined with the flexible rotating wheelset model,the coupling of the flexible rotating wheelset in the Euler coordinate system with the vehicle/track rigidflexible multi-body dynamics equation is realized.The rigid-flexible coupling dynamics software of the vehicle/track system is designed and developed.The software is used to calculate the influence of the rotating flexible wheelset on the wheel/rail interaction of the vehicle/track system,and an in-depth analysis is carried out.The research work is carried out and the innovative achievements achieved are as follows.(1)Considering the limitation of the wheelset flexibility by using the Lagrangian coordinate system,this paper adopts the flexible rotating wheelset model based on Euler coordinates,and derives the finite element discrete form formula of the relevant computational quantities in Euler coordinates.Based on OpenSees open source finite element software,the element level calculation function in Euler coordinates is developed.The modal and frequency response function of the rotating wheelset is calculated.The differences between the rigid wheelset,the negligible rotating wheelset and the rotating flexible wheelset in the dynamic response of the vehicle/track system are compared and analyzed.The necessity of considering the rotating effect of the flexible wheelset is proposed.(2)Based on the finite element and multi-body dynamics theory,combined with the wheel/rail three-dimensional geometric relationship and the wheel/rail contact force calculation method,the rail in the track system is set as a continuous elastic beam,and the rigid-flexible coupling dynamics model of the vehicle/track system is established.The coupling between the rotating flexible wheelset calculation in the Euler coordinate system and the vehicle/track multi-body dynamics model calculation under the Lagrangian coordinate system is realized,and the iterative calculation is completed.And then,a rigidflexible coupled dynamics model of vehicle/track system is proposed,which is more suitable for high-frequency response analysis of high-speed railway wheel/rail system.(3)The vehicle/track system rigid-flexible coupling dynamics software is developed,and the plug-in architecture and the design mode such as the factory method is adopted to ensure the openness,scalability and maintainability of the software.According to the software engineering theory,combined with the actual needs of the software,the crossplatform software development tool chain is selected.The vehicle/track system model parameter import,vehicle multi-body dynamics calculation,track and wheel/rail contact calculation and result data collection components are realized.Extension system and factory system components are designed and accomplished to improve code reuse and ease of function call.(4)In view of the high-frequency vibration problem of vehicle/track system caused by track irregularity in high-speed railway,the influence of rotating effect of flexible wheelset on the dynamic response of vehicle/track system is studied by using vehicle/track rigid-flexible coupling system dynamics model.The relationships between train speed,geometry of welded rail,stiffness and damping of vehicle/track system and high-frequency vibration response of vehicle/track system are studied from time domain and frequency domain.The frequency response law and the main frequency range of the vehicle/track system in the welding section are proposed,and the main influencing factors are discussed.(5)Aiming at the high-frequency vibration problem of vehicle/track system caused by rail corrugation,a dynamic model of vehicle/track rigid-flexible coupling system with rail corrugation section is established,and the influence of rotating effect of flexible wheelset on dynamic response of vehicle/track system in rail short-wave damage section is studied.The relationships between rail corrugation geometry,fastener system damping,sleeper spacing and periodic high-frequency vibration response of vehicle/track system are studied from time domain and frequency domain.The method of avoiding the resonance of the wheel/rail system in the rail corrugation section and slowing the wheel /rail interaction is explored,which can provide theoretical basis for the maintenance work of railway engineering.(6)A rigid-flexible coupling dynamic model of vehicle/track system considering wheel polygon is established for the high-frequency vibration of high-speed vehicle/track system caused by wheel polygons.The influence of rotating effect on polygonal response of flexible wheel is studied,and the relationships between polygon order,abrasion degree and train running speed and vehicle/track system dynamic response are studied.This paper explores the causes of the number of polygonal orders in a high-speed railway and the development trend of wheel polygon wear.Considering the wheel polygon order and the train running speed,the recommendation for the wear limit of the wheel polygon is proposed. |
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