The Finite Element Analysis Of Stress And Deformation For Aluminum Ally In Braze Welding

The 3A21 aluminum alloy has the perfect properties of plasticity, easy processing ,corrosion resistantance and better weldability,which has been popular used in aero space. But it need specific shape by means of welding craft in practice and need high precision than the toughness, so braze welding became the fit technology. Because it showed difference between the solder and base metal of the mechanical properties, thermal physical properties ,especailly the liner inflation in braze welding, so there may appear high thermal stress in the welding joints which induced deformation and influenced the precision of size ,then caused the failure of the structure and increased the cost. So analysis of the residual stress of welded structure taken the predominant place for structure design and craft.The highly nonlinear finite element analysis software MSC.Marc and thermal elastoplasticity method were adopted to analyse the distribution and change of stress in braze welding, with in consideration of the materials properties parameter transmutability with the change of temperature. A conception based on the front supposition, analysed the stress distribution and whole deformation of the box in braze welding, and surveyed the box deformation and certified the reliability through the use of three-dimensional coordinate.Optimized the clamp condition, then computated the box deformation and stress distribution in poptimized condition.The result showed that, the residual stress in Y direction and Z direction had a great influence on the toughness of the braze welding joints. There occurred the greatest residual stress of 164Mpa onto the contact area between the aluminum and solder. The residual stress was the smallest when the welded seam is 1mm, and it may reduce the residual stress effectively when exerted press in Y direction on the welding joints.The simulation result of the original clamp craft showed that, the greatest deformation was occurred in back of the box which was 11.49mm. the deformation range in Y direction of upside edge of aluminum box was 0～1.375mm, the deformation range in Y direction of upside median line of aluminum box was 2.128～4.245mm. The greatest residual stress was occurred in root edge of the box back and the residual stress was 155.8Mpa. The simulation result of the optimized craft showed that, the whole deformation of the box decreased, the greatest deformation was 1.25mm and the deformation range in Y direction of upside median line of aluminum box was 1.180～1.958mm. The residual stress of the box decreased ,the greatest residual stress in root edge of the box back and the residual stress was140.1 Mpa.