Research On Dynamic Performance Of Large-slope Rack Railway Bridge Based On Vehicle-bridge Coupling Theory

With the rapid development of China’s economy,the demand for the construction of rack railway in many mountainous areas and scenic spots in China is gradually increasing.Based on the 100 year development history of rack railway abroad,considering that the gear meshing force will affect the safety of bridge structure and passenger comfort,it is urgent to carry out the research on vehicle bridge coupling of rack railway considering large slope.In this paper,two kinds of gear rack finite element models are established,their meshing characteristics are studied,and a simplified formula of meshing force is proposed.Based on the train-bridge coupling vibration theory,the dynamic response of rack railway vehicle bridge system under large slope is solved,and the train running comfort is analyzed.The main research contents are as follows:(1)This paper introduces the development status of rack railway and toothed rail system,summarizes the research work carried out in rack railway at home and abroad,summarizes the research status of gear dynamics,and summarizes the related contents of vehicle-bridge coupling vibration.(2)According to the operation characteristics of rack railway,two kinds of gear rack parameters are determined with reference to the walking part of shearer and Strub toothed rail system.Based on the principle of mechanical meshing,the finite element models of two kinds of gears traveling on the rack are established by using ANSYS-Workbench software.By comparing the results,the meshing characteristics of each are analyzed,and a simplified formula of meshing force is proposed.(3)The dynamic analysis model of railway vehicle bridge system with large slope rack railway considering the meshing characteristics of gear rack is established.According to the theory of multi rigid body dynamics,the vehicle subsystem model is established,and the vehicle motion equation considering the degree of freedom of driving direction is deduced.The bridge beam subsystem model is established by using the vibration mode superposition method.The two subsystems are connected based on the vertical and longitudinal close wheel rail relationship.Considering the gear meshing force and the phase difference between traveling wheel sets,it is solved by the direct coupling method,and the calculation program is compiled.(4)The effects of tooth rail type,bridge slope and train formation on the dynamic response of vehicle bridge system are explored.The dynamic responses of bridges under different working conditions are compared and analyzed,and the horizontal and vertical comfort of trains are evaluated.It is found that the longitudinal displacement amplitude of pier top under different working conditions meets the limit requirements,and the longitudinal meshing force has a great influence on its amplitude.With the increase of slope,the amplitude of vertical displacement in the middle of the bridge span changes little.Taking the Sperling evaluation index of car body as the standard,the vehicle stability index of Strub gear rail system is better than that of shearer walking part system.(5)Ordinary wheel set and rail are added to the model of Strub gear rail system,and a complex model considering the interaction between ordinary wheel rail and gear is established.The tooth rail meshing force under different slopes is solved,the dynamic response of vehicle bridge system is compared and analyzed,and the influence of model parameters on driving comfort is explored.The results show that the stability index of car body is better than that of simple model after considering the action of ordinary wheel set.Increasing the linear stiffness of the pier has little effect on the horizontal stability index of the car body,but adjusting the vehicle parameters can significantly improve the comfort of the car body.