Z-pin/缝合对复合材料T型接头剪切承载能力的影响

利用三维有限元模型对Z-pin/缝合增强试验件进行有限元分析，采用内聚力模型模拟界面的破坏情况，通过在分层的上下界面加入非线性弹簧元来模拟Z-pin/缝合的增强机制，非线性弹簧元的力学性能（桥联律）由细观力学方法获得。通过与试验结果的对比发现，由于未进行界面增强的T型结构的剪切承载能力已较高，Z-pin/缝合增强较难提高T型接头的剪切承载能力。从少数几种可提高T型接头的剪切承载能力的增强方案中可看到，应选择拉伸强度较高而拉伸模量较低的缝线来进行T型接头剪切界面增强设计。

Effect of Z-pin/stitching on the shear carrying capacity of composite T-joints

Three-dimensional FEM models were used to simulate the Z-pin/stitching reinforced T-joint specimens. The interface failure was simulated with cohesive zone model, and the effect of Z-pin/stitching was simulated with nonlinear springs inserted into the interface. The mechanical properties of the spring, i.e. bridging law, were obtained based on a micromechanical approach. Comparing with experimental results and the FEM results, it is difficult to increase the shear carrying capacity of T-joints through Z-pin/stitching as the shear carrying capacity of unreinforced T-joint is quite high already. After analyzing the a few schemes which can increase the shear carrying capacity of T-joints, choosing stitch with high tensile strength and low tensile modulus was suggested to be used for the design of interface reinforcement.