Research On Dynamic Characteristics And Reliability Of High-Speed Train Gearbox

China ’s high-speed railway operating mileage ranks first in the world,and the national high-speed rail network has covered more than 94.7 % of the cities with a million-level population.China Railway has mastered the complete set of technologies for designing and manufacturing high-speed trains that meet various operating environments,with independent innovation capabilities,and has formed independent technical standards and design methods.During the driving process of high-speed trains,the reliability of each system determines the reliability of the whole high-speed train,which plays a vital role in the driving safety and capacity guarantee of high-speed trains.The gearbox system of high-speed trains is an important part of the transmission system of high-speed trains and a key link in the power transmission route of high-speed trains.Its reliability research is of great significance for the safety,reliability,and economy of high-speed trains.In this dissertation,a high-speed train gearbox is taken as the research object.Based on the analysis of the internal and external excitations of the gearbox,the bendingtorsion-shaft-swing coupling dynamic model of the internal gear transmission mechanism of the gearbox is established.The vibration characteristics of the gear transmission mechanism are analyzed.The admittance matrix of each part of the gearbox is established based on the substructure admittance method.Combined with the dynamic analysis results of the gear transmission mechanism and the admittance matrix of the gearbox,the vibration transmission characteristics and the main transmission paths of the gearbox system are analyzed from the perspective of vibration power flow.The influence of damping parameters and stiffness parameters on the vibration power of the gearbox system is analyzed.It provides reference for vibration control research of gearbox system and vibration mechanism analysis based on vibration energy transfer.Based on the theoretical analysis of the dynamic characteristics of the gearbox,the vibration acceleration of the gearbox of the high-speed train is collected.The kernel density estimation theory is used to evaluate the vibration of the gearbox system,and the vibration response threshold is determined based on the kernel density estimation results,which provides a reference for the vibration monitoring of the gearbox and the optimization of the vibration monitoring threshold.Based on Markov model,AK-MCS algorithm and Copula theory,the reliability analysis is carried out from the perspectives of system operation and maintenance and system operation process,which provides guidance for the optimization of operation and maintenance decision and dynamic reliability monitoring of gearbox system.The main research contents are as follows:(1)Dynamic modeling of high-speed train gearbox systemFirstly,the time-varying meshing stiffness,error excitation,meshing impact excitation and external excitation of the primary gear transmission mechanism inside the gearbox of high-speed train are analyzed.Then,based on the force and vibration displacement decomposition method,considering the meshing impact excitation,error excitation,time-varying meshing stiffness excitation and external excitation,the helical gear bending-torsion-shaft-pendulum coupling vibration model is established,the vibration load array of the gear transmission mechanism is obtained,and the vibration characteristics and vibration excitation of the gear transmission mechanism are analyzed.Finally,the admittance matrix of the key components is established based on the substructure admittance method.Combined with the dynamic analysis of the gear transmission mechanism,the coupling dynamic model of the gearbox system is established based on the power flow idea.(2)Vibration transmission characteristics analysis and vibration evaluation of high-speed train gearbox systemBased on the established vibration power flow model of high-speed train gearbox system,the hierarchical transmission path analysis of gearbox system is carried out.The main transmission paths of vibration are identified by the analysis results,and the influence of damping parameters and stiffness parameters on the vibration power of gearbox system is analyzed.Based on the gearbox vibration response data of the real vehicle test and the kernel density estimation theory,the vibration evaluation of the gearbox system is carried out.The optimal confidence interval of the kernel density estimation of the vibration response of each key component is determined,and the monitoring threshold of the vibration response of each key component is calculated.The analysis results and research methods provide reference for vibration monitoring and vibration monitoring threshold optimization of key positions of gearbox in real vehicle operation.(3)Reliability analysis of high-speed train gearbox based on vibration responseThe Markov state model of high-speed train gearbox system is established based on Markov theory.According to the analysis of the vibration acceleration response data of the gearbox,the signal is decomposed by the EEMD method,the response covariates and intrinsic dimensions of each key component are determined,and the WPHM model of each key component is established.The WPHM model parameters are estimated by the maximum likelihood estimation method.Calculate the real-time failure rate of each main part of the gearbox based on WPHM,evaluate the reliability state probability of the gearbox system and each key part based on the Markov state transition model,and analyze the influence of the failure rate and repair rate on the reliability of the gearbox system.Provide a reference for the optimization of the maintenance system of the gearbox system.(4)Research on thermal reliability of high-speed train gearbox based on fluid-solidthermal couplingThe heat transfer analysis and temperature rise distribution analysis are carried out on the high-speed train gearbox system,and the fluid-solid-thermal coupling analysis is carried out on the gearbox based on the finite element analysis software to determine the steady-state temperature field distribution.Based on the analysis results,a temperature rise test wined,which provided samples for the thermal reliability analysis of the key heat-generating components of the gearbox.Based on the AK-MCS algorithm,the thermal reliability of the gearbox is analyzed,and the influence of temperature on the reliability of the driving gear and the driving gear bearing are obtained,which provides a basis for the optimization of the temperature monitoring limit and the reliability of the high-speed train gearbox in the actual operation of the gearbox.(5)Research on reliability of high-speed train gearbox based on multi-failure mode correlationCombined with the classical stress-strength interference theory,the number of random loads is regarded as a Poisson process,and the strength degradation of the part is described by the Gamma process,and the Gamma strength degradation parameters of each part are determined by the part material or the P-S-N curve of the part.Considering the order statistics theory,time-varying load and strength degradation process,the stressstrength interference model of each key part of the gearbox is established,and the dynamic reliability of each key part is analyzed based on the model.The gearbox is regarded as a series system,Gumbel Copula function is introduced,the correlation between different parts and different failure modes of the same part is considered,and the nesting relationship of Copula function is determined.Based on the kernel density estimation and maximum likelihood estimation method,the parameter values of the Gumbel Copula function are calculated,and the dynamic reliability model of the highspeed train gearbox system is established to realize the evaluation of the dynamic reliability of the high-speed train gearbox.