单搭胶/螺栓混合连接结构的应力分布与载荷分配

针对平衡单搭胶/螺栓混合连接结构及其对应胶连接、螺栓连接结构,通过逐步构建其各自对应的精确三维有限元分析模型的方法对比分析了三种连接结构的应力分布。首先构建了胶连接分析模型,其胶层应力计算结果与采用已有文献理论分析模型计算结果比较吻合,验证了计算模型的准确性;在上述模型基础上继而构建了胶/螺栓混合连接分析模型,对比分析了采用两种胶材料的混合连接相对于对应单种胶连接层应力分布的变化,并计算了混合连接胶层与螺栓的承载比例,发现采用酚醛树脂胶的混合连接与对应胶连接胶层应力分布几近一致,螺栓分载很少,而采用丙烯酸酯胶的混合连接胶层剪切应力得到极大程度降低且螺栓得到了较大分载;最后构建了混合连接对应的螺栓连接分析模型,比较了两者应力水平和应力集中程度,发现前者明显低于后者,混合连接胶层的加入有缓解连接孔边应力集中的作用。提出混合连接可采用低模量胶材料以使胶层与螺栓共同分载,从而达到比传统连接方式更好的连接性能。

Stress distribution and load sharing in single-lap bonded/bolted joints

The stress distributions of three types of joints,namely balanced single-lap bonded/ bolted hybrid joint and corresponding bonded only joint and bolted only joint,were investigated and compared by gradually developing accurate three dimensional Finite Element Analysis(FEA) models.First,the FEA model of bonded only joints was built and employed to obtain the adhesive stress of the joint,which was in good agreement with that obtained by theoretical model in the literature.Then,the bonded only joint FEA model was extended to the bonded/bolted hybrid joint model.The adhesive stresses in the hybrid joints with two kinds of adhesives were compared with that in the corresponding bonded only joints.The load sharing ratios by the adhesive layer and by the bolt of the hybrid joints were calculated.Results show that the adhesive stress distribution of the hybrid joints with phenolic resin adhesive was almost the same as that of the corresponding bonded only joints;the bolt shared very little load.However,in the hybrid joints with acrylic resin adhesive,the adhesive stress decreased significantly and the bolt shared large load.Finally the FEA model of the bolted only joint corresponding to the hybrid joint was built.Comparison shows that hole stress concentration in the hybrid joint is much lower than that in the bolted only joint,which means the hybrid joint can effectively eases stress concentration.In hybrid joints with low modulus adhesive,load can be shared by the bolt and the adhesive.So the performance of the hybrid joints is better than that of traditional joints.