Strength Simulation And Fatigue Life Evaluation Of Subway Aluminum Alloy Car Body

Nowadays,the subway is the preferred mode of transportation for urban residents,and the car body is the most important part of the subway vehicle.Its strength is related to the safety and comfort of operation.The study of the strength of the car body is not limited to the static strength.With the deep understanding of the fatigue problem,fatigue strength analysis has become the top priority in the analysis of the strength of the car body.This article takes fatigue life assessment as the main line of research,and takes a certain aluminum alloy car body as the research object.This article first studies the development history and fatigue assessment status of aluminum alloy car bodies at home and abroad,and clarifies the advantages of aluminum alloys as car body materials and the importance of fatigue design methods in increasing the life of car bodies And a brief overview of traditional fatigue life prediction methods.Next,combined with the relevant knowledge of fracture mechanics,the theory of finite element method was studied,and the fatigue problem was systematically combed,focusing on four fatigue life assessment methods,namely the nominal stress method,hot spot stress method,notch stress method 3.Structural stress method,determine the nominal stress as the evaluation parameter to evaluate the fatigue life of the car body.This article then studies two standards for fatigue assessment using the nominal stress method,namely the DVS1608 standard and the IIW standard,and conducts simple verification through two examples,compares the characteristics of the two standards when evaluating the fatigue life of welded structures,and determines The DVS1608 standard is the main reference standard to check the fatigue strength of the car body.After determining the reference standard,according to the evaluation process of the DVS1608 standard and related algorithms,using the APDL programming language and the finite element analysis software ANSYS as the platform for secondary development,I wrote a MAC macro program based on the DVS1608 standard to evaluate fatigue life.Using Tcl/TK language for interface development,a fatigue life evaluation platform is built.This platform can embed a variety of evaluation methods and evaluation standards.When in use,the prepared macro program can be directly called through the evaluation platform.In the structural simulation stage,this article uses Hyper Mesh software to create a finite element model of a subway aluminum alloy car body,and determines the loading conditions according to the EN12663-2010 standard.It performs static strength analysis,stiffness analysis,and modal analysis.It shows that the above three meet the requirements of relevant standards.Finally,the prepared program is used to verify the fatigue strength of the car body and the weld on the vehicle.The results show that the fatigue strength of the car body base material and the weld meet the requirements of the DVS1608 standard.Finally,according to the EN15085 standard,the calculation of the stress factor and other relevant coefficients of the weld is completed,and the evaluation of the quality level and inspection level of the important weld is realized.The content studied in this thesis has important theoretical research and engineering application significance for the fatigue strength design of aluminum alloy car body and the evaluation of car body weld seam.