Numerical Investigation Of Thermo-mechanical Coupling Process During Laser Welding Of Aluminum Alloy Under Various Heat Sources

Abstract:Laser welding technology is a kind of high precision, high efficiency and reliable welding technique which is widely used in aviation and astronautics, automobile manufacturing and other fields. Laser welding includes a variety of complex mechanism, however, the studies of numerical investigation of thermo-mechanical coupling process during laser welding of aluminum alloy under various heat sources have not yet received enough attention. Only depending on the test method to research laser welding process and control of the welding process parameters is not easy to obtain the fully understanding. With the development of computer technology, numerical simulation technology has become a powerful means to simulate the whole process of laser welding.In this paper, based on simulation requirements of6063aluminum alloy laser welding thermo-mechanical coupling process, established a mathematical model and numerical method that based on ABAQUS finite element software. By different motional laser heat source loading, we study thermo-mechanical coupling mechanism of temperature field, stress field of laser welding of aluminum alloy and the influence of different laser welding process parameters, and propose an optimization scheme which can provides reference to enhance and improve the quality of welding. Specific work is as follows:First, during establishing the numerical model of the laser welding of aluminum alloy6063thermal coupling calculation, we consider the changing of thermal physical properties of material, the latent factor, convection and radiation between material and surroundings. The fully coupling method is adopted to simulate the temperature field、stress field of laser welding. Moreover, the motional laser heat source is loaded using Fortran language to edit subroutine DFLUX for realizing in ABAQUS finite element software.Secondly, by using the built numerical model, we simulate laser welding thermo-mechanical coupling process of6063aluminum alloy and analyze the impact of welding parameters to temperature field and stress field, in order to propose optimization methods, under different conditions of single laser, dual-beam laser and pulsed laser irradiation.Finally, through analyzing the simulation results, researcher shows that: compared three different laser heat sources, in the process of pulse laser welding, heat affected area and high-temperature region are minimum, the depth of molten along the direct of weldment thickness, the width of weld is narrowest, nevertheless, the longitudinal residual stress of weldment is maximum. The heat affected zone and high-temperature region of single beam laser welding are smaller than dual beam laser welding, the longitudinal residual stress of single beam laser welding is greater than dual beam laser welding. Dual beam laser welding is superior to single beam laser welding and pulse laser welding, but still having some deficiencies needed to optimize, in order to enhance the welding process level.