Analysis And Optimization Of Structure Performance Of Spot-welding Car Body

Now the level of urban development in our country is getting higher and higher.In order to alleviate urban traffic congestion and make full use of space,major cities have successively opened subways,and people have higher requirements for the safety,comfort and stability of subway vehicles.At present,stainless steel subway cars are still the mainstream.Stainless steel subway cars have the advantages of high strength,strong corrosion resistance,and light weight.Many vehicle factories have also been studying car body structures with better performance in various aspects,and are committed to the research of lightweight car body.The weight of the car body becoming lighter can not only reduce energy consumption but costs as well.Therefore,it is very necessary to perform performance simulation on the car body structure.Based on the above background this thesis takes a stainless steel spot welded metro car body as the research object,and conducts structural strength simulation analysis and structural optimization of the car body structure.The main research contents are as follows:First of all,investigate the status quo of domestic and foreign subway car research,understand the characteristics of stainless steel subway cars,and determine the research content and methods of this article.Analyze the advantages and disadvantages of the three modeling methods around the modeling method of spot welding,then select the most appropriate modeling method to perform finite element modeling of car body structure;Secondly,according to the EN 12663-2010 standard 20 representative static strength calculation conditions and 1 stiffness calculation condition were determined.Based on the fourth strength theory and the GB/T 7928-2003 standard respectively,static strength assessment and rigidity assessment for the stainless steel spot welding metro car body structure are carried out to evaluate whether both of them meet the requirements of the design and related standards;Thirdly,based on the theory of modal analysis,the unconstrained free modal analysis of the car body structure is carried out,the first ten modes of the car body are extracted,the vibration characteristics of the car body itself are studied,and the first order of the car body steel structure is investigated.Vertical bending frequency and first-order torsion frequency,to study the dynamic performance of car body structure;Forthly,the fatigue strength of the car body is calculated according to the fatigue load requirements of the car body specified in the EN 12663-2010 standard.The fatigue strength of the car body structure is evaluated in conjunction with the BS7608 standard to investigate whether the cumulative damage of each fatigue evaluation point is greater than one;Finally,the problem of multi-objective structure optimization of the car body is studied,and the influence of 12 sheet thickness parameters on the body structure quality,stress,displacement and the sensitivity of the first-order sag frequency is investigated.Based on the lightweight concept,carry out the multi-objective optimization of the car body structure and study optimized car body structure performance.