In-plane shear of nanostitched three-dimensional para-aramid/phenolic composites were experimentally investigated. Adding the nanostitched fiber into nanoprepreg para-aramid fabric preform composites slightly improved their shear strengths. The carbon-stitched composite exhibited comparatively better performance compared to the para-aramid stitched composite probably due to well bonding between carbon fiber and phenolic resin. The stitched nano composites had mainly matrix breakages and micro shear hackles in the matrix; matrix debonding and filament pull-out in the composite interface; fibrillar peeling and stripping on the filaments due to angular deformation. This mechanism probably prohibited extensive interlaminar opening in the nanostitched composites. The result exhibited that the introducing of the nano stitched fiber where multiwall carbon nanotubes were transferred to the out-of-plane of the base structure enhanced its transverse fracture as a form of confined delamination area. Therefore, the damaged tolerance properties of the stitched nano composites were enhanced compared to the base.

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三维纳米预浸料和纳米缝合芳纶/酚醛多壁碳纳米管复合材料：面内剪切的实验测定

对纳米缝合的三维对位芳纶/酚醛复合材料的面内剪切进行了实验研究。将纳米缝合纤维添加到纳米预浸料对芳纶织物预成型复合材料中，其剪切强度略有提高。与对位芳纶缝合复合材料相比，碳缝合复合材料表现出相对更好的性能，这可能是由于碳纤维和酚醛树脂之间的良好结合。缝合纳米复合材料主要有基体断裂和基体微剪切裂纹；复合材料界面中的基体脱粘和长丝拉出；由于角变形而导致长丝上的原纤维剥落和剥离。这种机制可能阻止了纳米缝合复合材料中广泛的层间开口。结果表明，将多壁碳纳米管转移到基础结构的平面外的纳米缝合纤维的引入增强了其横向断裂，作为一种受限的分层区域。因此，与基体相比，缝合纳米复合材料的损伤耐受性得到增强。