Reliability Analysis And Optimization Of Gear Transmission System Of EMU

In practical engineering application,gear transmission system is an important mechanical transmission mode.With the increase of EMU running speed,the safety problem of EMU gear transmission system is increasingly prominent,which puts forward higher requirements for the reliability of EMU gear transmission system,so it is necessary to conduct in-depth research on it.Based on the theory of reliability analysis and optimization,this paper uses polynomial function fitting and particle swarm optimization method,combined with computer finite element simulation technology,to analyze and optimize the reliability of EMU gear transmission system.The main research contents are as follows.Firstly,the reliability of gear pair and shaft is analyzed considering the influence of meshing dislocation and strength degradation.The maximum contact stress in the process of gear meshing is analyzed considering the meshing dislocation caused by shaft and bearing deformation.At the same time,nonlinear function is used to fit the relationship between traction torque and maximum contact stress of tooth surface,and gamma random function is used to describe the strength degradation process of gear material.Considering the strength degradation of gear,based on the stress strength interference theory,the limit state equation of contact strength of gear pair is established,and the reliability is analyzed by Monte Carlo method.In the same way,the reliability of the gear shaft in the gear transmission system is analyzed,and the relationship between the reliability of the two key components in the gear transmission system and time is finally obtained.Secondly,considering the failure correlation of the two failure modes of gear pair and shaft,a system reliability analysis method based on Copula function is proposed.Based on the reliability analysis of the key parts in the gear transmission system,the system reliability of the gear transmission system is analyzed.The series system reliability analysis method,the system reliability analysis method based on correlation coefficient and the system reliability analysis method based on Copula function are used to analyze the system reliability of the gear transmission system.By comparing the calculation results of the three system reliability analysis methods,it can be seen that the reliability analysis method of gear transmission system based on Copula function can more accurately describe the failure correlation of the key components of the system,and the system reliability analysis results are more in line with the engineering practice.Finally,based on the polynomial response surface function and particle swarm optimization algorithm,the gear modification is optimized to improve the reliability of the gear transmission system.On the basis of system reliability analysis,the system reliability is optimized based on the gear compound modification method.According to the finite element simulation results of gear transmission system model,the specific modification method and modification range of gear are determined.The orthogonal experimental design of the modification parameters is carried out,and the polynomial response surface surrogate model is established to fit the relationship between the modification parameters and the objective function;Particle swarm optimization(PSO)is used to optimize the surrogate model to obtain the optimal gear modification.The method can reduce the maximum contact stress,improve the eccentric load and improve the reliability of gear transmission system.