铝合金搅拌摩擦焊接加筋板剪切稳定性能研究

对2024-T3铝合金搅拌摩擦焊接加筋壁板的剪切稳定性能进行试验研究，得到该结构的剪切失稳形式及屈曲载荷、承载能力及破坏形式。应用有限元法对该焊接加筋壁板结构进行简化建模，对该结构的稳定性和承载能力进行计算，将计算结果与试验结果进行比较。试验及有限元计算结果表明，结构的剪切失稳形式表现为筋条间平板的局部屈曲；屈曲后结构进入张力场受力状态，破坏形式主要表现为平板的塑性变形和边缘撕裂、筋条的弯扭变形以及焊接区的局部脱焊；出现脱焊现象的试验件其承载能力较未出现脱焊现象的试验件下降7.7%；线性和非线性屈曲计算所得屈曲载荷分别比试验平均值高出18.4%和26.2%，而非线性计算所得承载能力比试验平均值高出5.7%，焊接引起的初始缺陷对结构承载能力的影响小于对屈曲载荷的影响；有限元分析得到的结构屈曲形式和失效形式与试验现象吻合，验证了有限元模型的合理性，但其仍需要进一步改进以考虑初始缺陷来减小计算误差。

Study on Stability Performance of Friction Stir Welded Aluminum Alloy Stiffened Panel under Shear Load

Shear experiment on friction stir welded 2024-T3 aluminum alloy stiffened panel specimens is conducted to obtain the buckling behavior and carrying capability of the structure. Finite element method(FEM) is applied to analyze the stability performance of the simplified structure model and the results are compared with experimental results. It is found that, buckling mode of the structure is local buckling of plate between stiffeners, post-buckling mode is under the state of diagonal tension, the failure patterns mainly contain the plastic deformation and tearing of plate, distortion of stiffeners and local weld debonding. Average carrying capability of specimens failed with weld debonding is 7.7% lower than that of other specimens. Buckling loads obtained by linear and nonlinear analysis are separately 18.4% and 26.2% higher than average experimental result, while carrying capability obtained by nonlinear analysis is 5.7% higher than average experimental result, which indicates that the carrying capability is less sensitive to the weld induced initial imperfections than buckling load. Buckling mode and failure pattern obtained by FEM accords well with experimental phenomenon, which validates the rationality of the finite element model, however, it still needs to be further modified to account for weld induced imperfections to reduce the calculation errors..