Simulation Study On Residual Stress And Deformation Of Large Welded Structure Of Hollow Aluminum Alloy With MIG

The hollow aluminum alloy has the advantages of small density,high specific rigidity,good welding performance,corrosion resistance and so on.It is used in the manufacture of train car bodies.In the manufacture of car bodies,MIG welding is mainly used for welding connections.However,there are two problems in the welding process of aluminum alloy.Excessive welding residual stress and excessive deformation,which lead to the machining accuracy and quality of the car body can't meet the use requirements.In this paper,the ABAQUS finite element software is used to study the welding process of typical joints and the welding process of the car body side wall respectively,to analyze the distribution law of welding residual stress,and to study the welding deformation law of the car body side wall.The main contents and conclusions of this paper are as follows:(1)The coupling relationship of temperature,stress and metallography in the process of MIG welding is analyzed,and the sequential coupling method is selected to solve the welding process.Based on the finite element simulation software ABAQUS,the simulation model of butt welding process is established,and the correctness of the simulation model is verified by comparison with the experiment.(2)The welding temperature and residual stress of butt joint,lap joint and T-joint are simulated by thermo-elastic-plastic method.The stress changes caused by temperature changes are analyzed,and finally the residual stress of the butt joint is about 240 MPa,and the residual stress of the lap joint and the T-shaped joint is about 245 MPa.(3)The longitudinal and transverse inherent strain coefficients of 6005 A aluminum alloy are calculated.The inherent strain method is used to calculate the welding residual stress of typical welded joints.By comparing the calculation results of the thermo-elastic-plastic method and the inherent strain method,it is found that the inherent strain method has relatively large error in calculating the residual stress at the end.Therefore,the inherent strain method and the thermal-elastic-plastic method are used to calculate the welding residual stress and deformation of the side wall of the car body.The longitudinal residual stress is about 233 MPa,and the maximum value of welding deformation is about 11 mm,with the increase of weld length,the amount of deformation increases obviously.The results show that,the finite element method is used to segment the car body and the welding process is simulated.The thermal-elastic-plastic method and the inherent strain method are used to calculate the residual stress and deformation of the large hollow aluminum alloy component.