Simulation And Analysis On Dynamic Characteristics Of High Speed Train Gear And Box

Gearbox is the key component of the driving system of high-speed train power bogie,and the gear transmission system and the box structure are the core parts to ensure the safe operation of the gearbox system.Due to the high-speed and heavy-load conditions,the gear meshing will always be accompanied by high-frequency impact.At the same time,the vibration response of the box under the internal excitation of the gear transmission is very complex,which will cause the resonance failure of the system.Therefore,it is very important to study the dynamic response of the gear transmission system and the box structure of high-speed train for the safety design of the high-speed train.In this paper,aiming at the gears and boxes of a certain type of high-speed train,the finite element method is used to carry out three-dimensional modeling of the modified gear pair,simulation analysis of gear transmission and study of influencing factors,analysis of box performance and vibration characteristics,and optimization design of gear and box topology.The main research work of this paper is as follows:(1)According to the gear modification scheme of a high-speed train and based on the principle of involute tooth profile formation,the gear profile and tooth orientation are corrected by MATLAB programming,and the coordinates of discrete points on the tooth surface are obtained.With the help of Imageware and ANSA software to fit the threedimensional tooth surface and combined with standard gear model,the three-dimensional modeling of modified gear pair is completed,which lays a foundation for the follow-up gear simulation analysis.(2)The finite element model of gear pair of a high-speed train is established,and the gear transmission is simulated by LS-DYNA solver.The gear speed,meshing force and meshing stress spot are obtained,and the feasibility of the finite element method is verified by comparing with the theoretical value.The influence of backlash and bearing clearance on gear transmission is studied.It is concluded that excessive backlash will cause the vibration of gear transmission to increase sharply,and the existence of bearing clearance will lead to the vibration of gear transmission to a certain extent.(3)Based on the modal analysis method,the first six natural frequencies and modes of the gearbox are obtained,and it is concluded that the modes of the gearbox are mainly thin-walled vibration.Combining with the dynamic response of the box under half sinusoidal acceleration pulse,it is concluded that the box is more sensitive to lateral and vertical impact.Based on the gear-box coupling finite element model,the influence of gear excitation frequency on the vibration characteristics of the box is studied.It is found that the vibration of the box is positively correlated with the gear meshing excitation frequency,while the axial self-excitation resonance of the large gear occurs at the motor speed of 3000 rpm.(4)Based on the variable density method,the topology optimization analysis of large gear and box structure is carried out.In order to improve the third natural frequency,the spokes of large gears are strengthened by combining the analysis results of gear optimization.The remarkable optimization effect is verified by gear modal analysis and gear-box coupling transient analysis.In order to improve the vibration of the box under internal excitation,the reinforcement bars of the box structure were rearranged.Through the transient numerical simulation of gear-box coupling,it was found that the optimization effect was good.