Finite Element Analysis Of Stress And Distortion For Sheet Aluminum Alloy T-joint In Double Laser Beam Bilateral Welding

With transportation manufacturers continuously purse on the promotion of competitiveness, thesheet aluminum alloy is widely used for its superior performance, which can effectively reduce theweight of vehicle and improve strength of the structure. As domestic research for DLBSW (doublelaser-beam bilateral synchronous welding) is still in its infancy, it is a powerful assistant method forsimulation technology to solve practical engineering problem. Based on this background, the finiteelement analysis on DLBSW process of large aircraft fuselage panels T-joint is carried on.First of all, the model is simplified and the process scheme is extracted according to the actualsituation. The finite element model uses subroutines to load dual laser beam heat resource and fill theweld metal, and the application of transition mesh and parallel distributed technology improve thecomputational efficiency significantly.According to T-structure of single stringer, the effects of different heat source models on thetemperature field are analyzed. An appropriate model is selected and then checked by experiment, amore accurate temperature field is obtained. Based on the checked heat source model, the weldingparameters are optimized, and stress field and deformation field of the workpiece are investigated.The results indicate that compressive stress existed in the regions near the pool during the weldingprocess, and it changes to tensile stress after welding. The biggest deformation of the structure occursin the center of either side of the bottom board, which is a composite of deflection and angledeformation. The applicability of the FEM model is verified by the testing of stress and deformation.Based on muli-stringer structure three-dimensional model has also been developed to analyzewelding process of different welding sequences, whose result show that welding orders have littleaffection on temperature filed and stress field but the deformation is opposite. For the whole fuselagepanel, crossing symmetry welding order which can get the minimum distortion after welding problemis the best scheme.In this paper, the analysis about DLBSW process of aluminum alloy sheet T-joint structure makesup for the limitation of experiment to some extent and improved production efficiency, which lays atheoretical foundation for the forming process of large aircraft fuselage panels.