纤维金属层板铆接剩余强度影响因素研究

为研究单搭铆接接头中纤维金属层板耦合损伤行为，运用金属硬化Johnson-Cook失效准则、纤维增强复合材料三维Hashin损伤准则、脱层B-K失效理论以及刚度退化失效准则建立了纤维金属层板铆接渐进失效模型，并结合实验验证了模型的合理性。考察了单搭铆接二次弯曲效应、层板铝合金体积分数、预紧力、层板孔边距对纤维金属层板铆接强度和失效模式的影响，为提高纤维金属层板铆接剩余强度提供可靠建议。分析结果表明：二次弯曲效应加速损伤发生，从而降低层板铆接强度，其中偏心加载可以削弱二次弯曲效应，更好地提高铆接强度；层板铝合金体积分数的增大能够提高层板铆接强度，但当体积分数大于50%时层板铆接比刚度和比强度反而下降；预紧力的增加能够提高层板铆接强度和增强层板损伤抗力；随着孔边距的递增，铆接剩余强度有所提高，破坏模式由灾难性拉断失效模式逐渐转化为理想的挤压失效模式，但当孔边距达到一定数值时，铆接强度不再明显提高，而失效模式也维持为挤压破坏。

Research on Influence Factors for Residual Strengths of Fiber Metal Laminates in Rivet

In order to study coupled damage of fiber metal laminates in a riveted single lap joint, a progressive failure model for fiber metal laminates was established by using the Johnson-Cook failure criterion for metal, the 3D Hashin damage criterion for fiber reinforced composites, the traction-seperation law for interface delamination and the stiffness degeneration theory of composites. The effectiveness of the present models were verified by experiments. The effects of the secondary bending, aluminum alloy fraction, pretightening forces, hole-edge distances on riveting strength and failure mode of fiber metal laminates were investigate to provide feasible suggestions for the design of riveted single lap joints of fiber metal laminates. The following conclusions are drawn: (1)The secondary bending speeds up laminate damage and reduces the riveting strength of laminates, and medium eccentric loading may weaken secondary bending and improve riveting strength better; (2)The increase of aluminum alloy fraction may improve the residual strength of laminates, but when it is greater than 50%, the specific stiffness and strength of the laminates will decrease; (3)The increase of pretightening forces may delay the damage initiation of fiber and matrix, and enhance strength of the riveted joint, thus improving the damage resistance of laminates; (4)With the increasing of the hole-edge distance, the residual strength of the riveted joint is improved, and the failure mode transform from catastrophic net-tension failure mode gradually into an ideal crushing failure mode, but when the hole-edge distance reaches a certain value, the residual strength is no longer significantly improved, and the laminate maintains crushing failure modes.