不同针刺工艺的针刺复合材料面内拉伸强度分析

6种针刺工艺不同的碳纤维增强树脂基复合材料，其面内拉伸强度随着针刺密度和针刺深度的增大而降低，针刺处纤维的断裂使材料内的缺陷失稳扩展和面内纤维断裂，进而使材料整体拉伸失效。根据面内拉伸实验结果和纤维累计损伤理论并引入纤维体积折减系数，建立了分析针刺复合材料面内拉伸强度的理论模型。这个模型的预测结果与实验结果相符，并发现断裂纤维簇的个数与体积折减系数相关。用该模型可预报不同针刺工艺复合材料的面内拉伸强度，并指导设计针刺复合材料的预制体。

In-plane Tensile Strength for Needle-punched Composites Prepared by Different Needling Processes

The in-plane tensile strength of six carbon fiber reinforced resin-based composites with different needle punching processes decreases with the increase of needle punching density and needle punching depth. The fiber fracture at the needle punching regions can make the defects instability propagation in the material, which can induce the tensile failure of material. Based on the in-plane tensile test results and fiber cumulative damage theory, a theoretical model for analyzing in-plane tensile strength of needle punched composites are established by introducing fiber volume reduction coefficient. The prediction results of this model are consistent with the experimental results. It is found that the number of broken fiber clusters is related to the volume reduction coefficient. The model can be used to predict the in-plane tensile strength of composites with different needling processes, and to guide the design of the needle punching preforms.