| Auxiliary converter can provide safe and reliable power supply for vehicle accessory equipment and control system,which is one of the most important equipment on the train.The cabinet of auxiliary converter can ensure the safety of electrical components when they work.With the renewal of technology,higher requirements are placed on the design of cabinets,and the trend of current research is lightweight design,reliability,dynamic characteristics and fatigue analysis.Therefore,theoretical research on cabinet structure design is needed.This paper takes a new type of subway auxiliary converter cabinet as the research object,and carries out the dynamic response analysis,vibration fatigue analysis and optimization design.Considering the accidental impact and the multi-directional random vibration of auxiliary converter during normal operation,the dynamic characteristics of structure are analyzed.The first ten natural frequencies and mode shapes of auxiliary converter cabinet were calculated using ANSYS software,which was found that the local mode dominated and the vibration mainly occurred on the plate structure such as bottom plate and cover plate.The transient analysis results showed that the maximum stress occurred at the lifting position and the welding position of structure during impact vibration.And compared the results of vibration stress and displacement in different directions,it was found that the longitudinal shock had the greatest impact on the results,and then is the vertical and horizontal direction.Through the random vibration analysis of the structure based on IEC61373:2010 and IEC 61373:1999 respectively,it was found that their stress values of random vibration both met design requirements,but IEC61373:1999 has got a higher valve.Considering safety,it is recommended to analyze the structure according to IEC61373:1999.Based on the frequency domain method,the random vibration fatigue analysis of the structure was carried out.According to the theory of random vibration and Miner linear fatigue cumulative damage,the fatigue damage value of structure was obtained that D was0.0134,and the fatigue life met the design requirements.In order to study the effect of stress amplitude distribution mode including narrow-band method and Dirlik method,and fatigue failure evaluation criterion including maximum principal stress criterion and critical surface criterion on fatigue results,the structural fatigue life was calculated by these 4 cases.The calculation results showed:(1)the fatigue life obtained by narrowband method was smaller than that obtained by Dirlik method.(2)The fatigue values obtained from different fatiguefailure evaluation criteria had little difference,indicating that fatigue failure evaluation criteria was not the main factors that affect the fatigue life of random vibration.When analyzing the fatigue life of random vibration,anyone can be selected.Finally,considering the complex structure of cabinet,the conservative design will be carried out in the traditional design so that the strength and stiffness of structure have great allowance and can be further optimized.Therefore,in this paper,an efficient structure optimization method was proposed by integrating finite element method,design of experiments,approximation models and global optimization algorithm.This method combined the finite software ANSYS and the optimization software Isight.First of all,choosing the design variables which have large influence on constraint condition and objective function by the method of optimal Latin hypercube design;then,the response surface model was set up.Finally,the approximate model was optimized by using the particles swarm optimization.The optimization results showed that the method can effectively improve the optimization efficiency,and the lightweight design of the structure is realized,which the weight was reduced by 11.61%. |
PDF Full Text Request