Numerical Simulation of Temperature Field and Residual Stress of T Welded Joint of Aluminum Alloy

Abstract

The numerical simulation of residual stress of aluminum alloy welded joints can optimize the welding process and increase the joints strength. In this paper, the Gauss distribution heat source model and ANSYS finite element method were used to simulate the MIG welding of T-joint of aluminum alloy. The actual weld molten was obtained by experiment and compared with the numerical results of temperature field. The residual stress of T-joint of aluminum alloy under three kinds of current was calculated by elastic-plastic theory and incremental method. The results show that the finite element calculation results are in good agreement with the actual molten pool, which indicates the accuracy of the finite element simulation calculation. The welding residual stress mainly concentrates on the weld zone, and the longitudinal tensile stress on the weld is larger and the longitudinal compressive stress is smaller. With the increase of welding current, the maximum residual tensile stress of the weld increases gradually. Introduction Aluminum alloy welding structure is widely used in automobile, ship, high-speed railway, aviation, aerospace and other fields. Because welding is a process of local rapid heating to high temperature and subsequent rapid cooling, and the characteristics of high thermal expansion coefficient, high thermal conductivity, small elastic modulus and low yield strength at high temperature of aluminum alloy make the aluminum alloy junction. The residual stress of the components is large, which has a great influence on the stiffness and strength of the members. The fatigue crack and stress corrosion crack are easy to be induced by large welding residual stress, which reduces the load-carrying capacity and service life of aluminum alloy welded structures [1] . In order to reduce the residual stress and its hazards, it is necessary to accurately predict the distribution characteristics of welding residual stress. The residual stress data measured by experimental means are usually only a few local measuring points, which cannot reflect the distribution of stress and deformation of welded parts as a whole. By means of thermo-elastic-plastic numerical simulation of welding process, the magnitude and distribution law of welding residual stress and deformation can be fully reflected. Only a few validation experiments are needed to prove the practicability of the numerical method in dealing with a certain problem. A large number of other project designs, optimum process methods and welding parameters can be screened by the method. The computer is complete. It plays a key role in controlling and reducing welding residual stress and deformation, and saves a lot of manpower, material and financial resources [2] . In welding numerical simulation, the accurate selection and establishment of welding heat source model is very important to the efficiency of numerical calculation and the accuracy of calculation results. Sen Li [3] studied the deformation of TIG welded T-joints of aluminum alloy, Liang Zhu [4] studied the mechanism of the influence of the uneven mechanical properties of materials on the yield strength and tensile strength of butted joints, Liang Zhang [5] et al. studied and simulated the welding process of 2024 aluminum alloy for medium and heavy plate, and Pi-yang Jiang [6] simulated by finite element method and X-ray. Residual stress characterization and stress relief by induction heat treatment for 2219 aluminum alloy with different welding methods were studied by linear diffraction