This study compares the flexural properties of unreinforced and Z-fibre reinforced 3D carbon/epoxy composites. Z-fibre reinforcement is introduced by a novel stitching pattern where uniform distribution of Z-fibres is achieved by inserting linear and angular stitch loops. Flexural tests were performed on both normal and parallel to stitching directions. Z-fibre reinforcement caused reduction in composite density and fibre volume fraction due to local gaps introduced by the needle insertion, which are filled with epoxy resin, resulting in resin rich regions and affecting flexural behaviour. Z-fibre reinforcement reduced the flexural strength and modulus of the composites (up to 27% and 39%, respectively), while the toughness of the Z-fibre reinforced 3D carbon/epoxy system is improved, since damage is more progressive in nature rather than sudden and brittle like fracture. Strain to failure increased from 1.9% to almost 2.8%, a significant improvement, resulting in more damage tolerant behaviour.

本研究比较了未增强和 Z 纤维增强 3D 碳/环氧树脂复合材料的弯曲性能。Z 纤维增强是通过一种新颖的缝合模式引入的，其中通过插入线性和有角度的缝合环来实现 Z 纤维的均匀分布。在垂直和平行于缝合方向上进行弯曲测试。由于针插入引入的局部间隙，Z 纤维增强导致复合材料密度和纤维体积分数降低，这些间隙充满环氧树脂，导致树脂丰富的区域并影响弯曲行为。Z 纤维增强降低了复合材料的弯曲强度和模量（分别高达 27% 和 39%），同时提高了 Z 纤维增强 3D 碳/环氧树脂系统的韧性，因为损坏本质上更具有渐进性，而不是像断裂那样突然和脆弱。应变失效率从 1.9% 增加到近 2.8%，这是一个显着的改进，导致更耐损坏的行为。