| The technology of high speed railway has developed and improved continuously in recent years,and the research of reliability has been paid more and more attention to the engineering designer.With the popularization of the electrified high speed railway,it is very important for the research on reliability.The pantograph,as the important electrical equipment to get the electric energy from the catenary for the EMU,has been working with adverse environment.In fact,the pantograph has been influenced by random factors such as external aerodynamic load,vibration and friction between pantograph and catenary.The presences of these random factors are easy to cause fatigue failure for the pantograph.To ensure the safety and reliability for the pantograph,it is necessary to conduct the fatigue reliability analysis.Based on this,fatigue reliability optimization and robust optimization analysis of the EMU pantograph has been conducted to improve the pantograph fatigue reliability and robustness.The theory of robust design,fatigue reliability design and optimization design have been combined to carry out the computer simulation analysis,and those analysis results can make ensure the safe and reliable for EMU operation.The main research work of this paper is as follows:(1)The static strength reliability analysis of pantograph.First of all,the pantograph static strength anslysis is condected by using the finite element analysis software of HyperMesh and ANSYS.Throwth static strength anslysis,the two under the conditions of the pantograph maximum working stress values are obtained.Also,the place of the maximum stress occurrence has been obtained.Then,the static strength check of the pantograph is completed throwth comparing with the maximum working stress and the allowable stress of the material.Secondly,the static strength reliability analysis is carried out basis on the analysis of the static strength for the pantograph.The pantograph structure parametric modeling is established.In this parametric modeling,static strength failure is used as a criterion to judge the failure of structures.At the same time,the maximum working stress of the pantograph is less than the allowable stress as the reliability evaluation standard.In this way,the limit state equation is established.And then,the pantograph static structure strength reliability is obtained by choosing Monte Carlo method in the probability design module of ANSYS software to analysis the parametric modeling.(2)Fatigue reliability analysis of pantograph structure.A hybrid simulation method of Monte Carlo and response surface is proposed to analyze the pantograph fatigue reliability based on the nominal stress method and Miner cumulative damage theory.Considering the external aerodynamic load,vibration and friction,material properties and other random factors between pantograph and catenary of pantograph,which are defined as the input variables,and also,the probability distribution is determined.Then,a limit state equation to analysis fatigue reliability of the pantograph is established.Where,fatigue failure is used as a criterion to judge the failure of structures,and the maximum working fatigue life of the pantograph is less than the design fatigue life as the fatigue reliability evaluation standard.In this way,the APDL language is used to white the fatigue reliability analysis procedures,which is embedded into the parametric model of the pantograph.On this basis,the hybrid simulation method is choosed to analysis the pantograph fatigue reliability.(3)Fatigue reliability optimization analysis of the collect head support.Considering the fluctuation of the random factors,which cause the fatigue failure for the collect head support of pantograph.In this paper,a method based on response surface of six sigma reliability optimization is proposed combining with the experimental design,finite element analysis and reliability optimization design.The pantograph fatigue reliability is treated as constraint condition,the quality of collect head support is treated as the optimization goal,and then,the fatigue reliability optimization model of collect head support is established.At laste,the optimization toolbox of MATLAB software is used to solve this optimization model.It can be seen from the results that fatigue reliability meets design requirement,also,the lightweight design of collect head support has been achieved.(4)Robust optimization analysis of the collect head support fatigue life.Considering the influence of random material properties,structure of the external load and size of collect head support fatigue life fluctuation,six sigma robust optimization has been conducted for fatigue life of collect head support.This optimization method combined with six sigma standard,robust optimization design and fatigue reliability analysis is to reduce the sensitivity of fatigue life of collect head support to random factors.The sensitivity of collect head support fatigue life by reducing the random variables such as external load,material properties and size range of structure.In this way,the fatigue life robustness of the collect head support has been improved greatly. |
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