| In recent years,China's shipbuilding industry is developing in a greener,more reliable and lighter direction.Aluminum alloy is widely used in shipbuilding due to its advantages such as high specific strength,high corrosion resistance to sea water,easy processing and forming,and non-magnetism.However,the welding strength of aluminum alloy is greatly affected by the welding process.Especially the welding residual stress is the key factor which affects the joint performance besides the welding technique.It is also a factor that must be considered when studying the joint performance.It is of great engineering significance for aluminum alloy to be widely used in the field of ship to carry out research on the generation mechanism of residual stress of aluminum alloy welded joint,the law of division and its influence on joint performance,and improve the welding performance of aluminum alloy structure.The main purpose of this paper is to evaluate the joint performance of 5052 aluminum alloy molten electrode gas shielded welding(MIG).The influence of welding residual stress is also considered in this process.Therefore,the magnitude and distribution of residual stress should be evaluated first.Determine the degree to which residual stress may affect joint performance.To carry out this evaluation.In this paper,two evaluation methods,finite element method and test method,are selected.To ensure the accuracy of the evaluation;Then,the mechanical and fatigue properties of the joints before and after residual stress relief were compared.Determine the influence of a certain value of residual stress on joint performance.In order to complete this research,this paper is mainly divided into the following aspects:(1)Combine research at home and abroad.The mechanism of the residual stress is described in detail.The generation and distribution of welding residual stress are emphasized.The research method of welding residual stress is introduced.The theory and basic method of calculating welding temperature field and stress field by finite element method are emphatically introduced.(2)The concrete steps of finite element simulation of aluminum alloy flat butt welding with ANSYS Workbench module are introduced in detail.It includes three parts: the establishment of finite element model,temperature field analysis and stress field analysis.The distribution of residual stress in aluminum alloy welded joints was obtained.The existence state of longitudinal stress and transverse stress in weld and heat affected zone is analyzed.The magnitude and distribution of longitudinal stress along four critical paths are studied.It is used as a comparison object of the test results;(3)In order to more accurately evaluate the magnitude and distribution of residual stress.In this paper,the ultrasonic method is used to weld the workpieces with the same size and process.The same 4 paths were selected to carry out residual stress test.The magnitude and distribution of longitudinal stress along each path are obtained.The results are compared with the finite element simulation results.The comparison results were used to evaluate the accuracy of residual stress simulation by finite element method.(4)In order to eliminate welding residual stress.In this paper,the residual stress relief test of welding is carried out by annealing method.The properties of welded joints before and after the elimination of welding residual stress were compared.The tensile performance,bending performance and fatigue life of the welded joint were compared.The tensile strength and bending properties of the welded joints under different treatment conditions were obtained.And before and after welding residual stress relief.The fatigue life value of the welded joint under different stress levels and the fatigue life curve of the welded joint when the load ratio is 0.1 are obtained. |
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