Study On Performance And Fatigue Of Welded Structure Of A Heavy Haul Railway Freight Car Body

With the improvement of the running speed and axle load of railway freight cars,the static strength and fatigue strength conditions to be met in the design process of their products have gradually become more stringent.Using the finite element analysis method,taking a heavy-duty railway truck as the main body,this paper studies the performance of the car body and the fatigue strength of the welded structure,evaluates the static strength and stiffness performance of the car body according to the relevant standards,and makes a test comparison.Focusing on the fatigue evaluation of welded structure of heavy haul railway freight car,AAR standard and structural strain method are used to predict the weld life.Finally,the results are compared with those obtained by nominal stress method,which can provide a valuable reference for the fatigue evaluation of body performance and welded structure of heavy haul railway freight car in China.The specific research methods and contents of this paper are as follows:(1)The development status of fatigue problems of welded structures at abroad and home is summarized;The basic theory of finite element is introduced;Basic terms,composition and characteristics of welded structure;The main modes of weld fatigue failure are discussed;Two kinds of methods for fatigue analysis of welded structures are summarized.(2)The structure,materials and performance parameters of a heavy haul railway freight car body are introduced,and the finite element model of freight car body is established and solved by using Hyper Mesh,ANSYS and Hyper View software.(3)The evaluation standards of static strength and stiffness of car body are introduced.According to the standard requirements of American AAR M-1001-2007 code for design and manufacture of freight cars,10 static strength working conditions of car body are simulated and calculated,and the results are analyzed.(4)The static strength test of heavy haul truck body is carried out,the test operation method and technical requirements are introduced,the patch position is marked,the static strength and stiffness test data of car body are compared with the simulation results,and finally the causes of errors are analyzed.(5)According to maynar’s linear cumulative damage theory,the traditional nominal stress method is used to analyze the fatigue strength of the weld of the car body,calculate the mileage life,and judge whether the car body meets the design requirements according to the calculation results.(6)The fatigue life of the above car body welds is predicted again through the main E-N curve and structural strain method,and whether the car body meets the design requirements is judged according to the calculation results.Finally,the fatigue prediction results of nominal stress method and structural strain method are compared and analyzed.