Structural Strength Analysis And Weld Fatigue Evaluation Of High-speed CRH Body

Nowadays,the country is developing rapidly,accompanied by a large number of population flows between cities.High speed railway provides strong transportation capacity support for national development.High speed train is the main means of transportation of high-speed railway.Aluminum alloy car body is mainly composed of profiles,plates and welded structure.With the continuous improvement of train running speed,the safety of welded structure of high-speed train body has become a hot spot,and many key problems need to be further studied.Based on the finite element method and different fatigue evaluation methods,taking the aluminum alloy high-speed train body as the research object,this paper evaluates the structural strength of the body and the fatigue life of the welded joint.Various forms of welded joint models are constructed.Based on the error analysis method,the relationship between the form of welded structure and the fatigue life of welded joint is studied,and a good evaluation effect is achieved.The full text is divided into the following parts:Firstly,the relevant background of train operation is investigated and studied,the multiple factors leading to stress concentration are studied,the characteristics of the current mainstream fatigue life calculation methods are analyzed and compared,the research contents of welded structure form and stress concentration in the existing standards are summarized,and the research method of this paper is determined;Secondly,the finite element modeling of an aluminum alloy car body is carried out,the calculation conditions of static strength and stiffness are determined according to the standard EN12663-2010,and whether the static strength and stiffness of the aluminum alloy car body structure used in this study meet the requirements of relevant standards are evaluated;Thirdly,the fatigue strength of the car body is calculated according to the standards EN12663-2010 and GB/t32059-2015.The structural stress method is used to evaluate the fatigue strength of the welded structure in the car body,and observe whether the fatigue damage ratio of the welded structure in the car body meets the requirements.On this basis,the sensitivity of the fatigue life of each weld to the relevant input conditions is further studied,and the influence degree of different loads on the key positions is revealed;Finally,three models of welded structures are established,the stress distribution of different types of joints is calculated and analyzed,and two fatigue life evaluation methods are used to evaluate the life of welded joint models.The fatigue life data related to the variation of welded joints are extracted,and a variety of data fitting techniques are used for data processing.The fitting results are compared,and the most suitable fitting function curve is constructed.Various forms of welded joint models are constructed by using aluminum alloy car body,the allowable degree of welded joint variation in vehicle structure is analyzed,and the application of fitting curve formula in complex structure is completed.