拘束条件对薄板T形接头双光束激光焊接变形的影响

采用单元温度对单元进行生死控制的有限元计算方法研究了拘束条件对2.5 mm厚铝锂合金5A90薄壁T形接头双光束激光焊接变形的影响,拘束条件包括对筋板施加和对底板施加两类,约束在焊接过程中施加,焊后冷却到室温去除.筋板拘束条件施加在筋板顶部和侧面,对比了施加与不施加约束两种情况,该两种情况连续焊接之前都采用点固焊对筋板进行固定.底板拘束条件通过在T形接头两侧设置压块对底板施压来实现,研究了压块与焊缝不同距离对焊接变形的影响.最后进行了试验验证.焊接过程中对筋板施加约束有利于减小焊接过程中及焊后筋板变形.底板纵向约束影响T形接头焊件挠曲变形的大小和方向,对角变形影响不大.焊接过程中对底板施加y向约束,有利于减小角变形.对底板加纵向约束与不加纵向约束两种情况进行了试验验证,变形方向及变形量最大值的计算结果与试验结果符合.

Influence of constraint on welding deformation of T joint welded by dual-beam laser

The influence of constraint on welding deformation of Aluminum-Li alloy 5A90 T joint welded by dual-beam laser was studied. The constraint studied in this paper included two categories, one was applied to stiffener, and the other was applied to base plate. In the case of stiffener, the constraint was applied to the top and lateral face. The stiffener was fixed on the base plate by tack welding before the continuous welding began. Two situations were compared, one is that the constraint applied on the top and the lateral face were unloaded after tack welding, and the other was not. In the case of base plate, constraint was applied by pressing block, which was pressed on the base plate from two sides of the stiffener. The influence of the distance between the stiffener and the pressing block on welding deformation was studied. The computational result was validated by experiments. The deformation of stiffener during welding and after welding when constraint was applied on it was smaller than that condition that constraint was not applied. The longitudinal constraint applied to the base plate influenced the amount and the direction of bending deformation, but had little influence on the angle deformation of the T-joint. The constraint applied to the base plate in y direction during welding contributed to the reducation of angle deformation. The computational results of deformation direction and amount of bending deformation were consistent with experimental results.