夹具拘束下大型薄壁铝合金结构搅拌摩擦焊接变形特性

采用应力分区映射法对大型薄壁铝合金结构搅拌摩擦焊接工艺进行了仿真计算，并通过实验验证了该方法的计算精度，从机理上分析了搅拌摩擦焊接的变形行为，在此基础上研究了不同夹具拘束对不同尺寸的大型薄壁结构焊接变形的影响规律。结果表明，夹具释放前，焊接件存在的沿厚度方向的应力梯度是导致搅拌摩擦焊接薄板纵向翘曲变形的根本原因；对于一般的焊接件，拘束距离较小的约束方式可以有效地抑制焊接变形；随着焊接件长度的增大，其焊接变形明显增大，装夹位置对焊接变形的影响效果更加明显。

Friction Stir Welding Deformation Behaviors of Large Thin-walled Aluminium Alloy Structures with Different Clamping Restraints

The stress mapping method was applied to simulate the welding processes of FSW for large thin-walled aluminum alloy structures. The calculation accuracy of this method was verified by experiments as well as the mechanism of welding distortion was studied. Then, the influences of different fixture constraints on the welding distortions of large thin-walled structures with different sizes were investigated. The results show that the stress gradient along the thickness of the welded parts before releasing the clamp is the main reason for the longitudinal warping deformations of thin plates by FSW. For general welded parts, the welding deformations may be reduced effectively with a smaller restraint distance. With the increase of the dimension of the welded parts, the welding deformations increase obviously, and the influences of the clamping positions on the deformations become more apparent.