The use of carbon and kevlar fiber-reinforced composite materials continues to grow in high-tech applications such as aerospace engineering. One of the most desired properties in composite structures is a strong interfacial bond between the matrix and the fiber. Nano-material reinforcement is one of the most preferred methods for strengthening the fiber-matrix interfacial bond. In the present research, polyamide 6.6 (PA 6.6) nanofiber and multi-walled carbon nanotubes (MWCNTs) reinforced kevlar fabric (KF), carbon fabric (CF) and epoxy matrix nanocomposite plates were produced by functional grading of these two fabrics. PA 6.6 nanofibers, obtained by electrospinning, were placed between the layers, and 12-layer nanocomposite plates were fabricated using a vacuum-assisted hand lay-up method. In producing MWCNTs reinforced nanocomposite plates, 0.3 wt.% of MWCNTs were added into the epoxy matrix. A comprehensive set of 16 distinct composite plates was manufactured, encompassing unreinforced plates, plates reinforced with MWCNTs, plates reinforced with PA 6.6, and plates reinforced with a combination of PA 6.6 and MWCNTs (PA 6.6-MWCNTs). The impact strengths of the produced composite plates were investigated at energy levels of 20, 40 and 60 J. The effects of reinforcing the composite structure with MWCNTs, PA 6.6, and PA 6.6-MWCNTs, as well as functionally grading KF/CF on impact strength, were investigated in detail. The damages that occurred in the material as a result of the low-velocity impact tests were interpreted by examining the high-resolution camera and optical microscope images. Thus, the nanofiber and nanoparticle reinforcement to composite structure and hybridization effect were evaluated together. With the reinforcement of PA 6.6, MWCNTs and PA 6.6-MWCNTs, the impact strength of the nanocomposite samples increased significantly compared to the unreinforced samples. Moreover, the amount of damage caused by the low-velocity impact test in reinforced samples was significantly reduced.

中文翻译：

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聚酰胺 6.6 纳米纤维增强的功能梯度凯夫拉尔/碳环氧树脂纳米复合材料和 MWCNT 在低速冲击下的损伤行为


碳纤维和凯夫拉纤维增强复合材料在航空航天工程等高科技应用中的使用持续增长。复合材料结构中最理想的特性之一是基体和纤维之间的牢固界面结合。纳米材料增强是加强纤维-基体界面结合的最优选方法之一。在本研究中，通过对这两种织物进行功能分级，生产了聚酰胺 6.6 （PA 6.6） 纳米纤维和多壁碳纳米管 （MWCNT） 增强凯夫拉织物 （KF）、碳织物 （CF） 和环氧树脂基纳米复合板。通过静电纺丝获得的 PA 6.6 纳米纤维放置在各层之间，并使用真空辅助手糊法制造 12 层纳米复合板。在生产 MWCNTs 增强纳米复合板时，0.3 wt.% 的 MWCNT 被添加到环氧树脂基体中。制造了一套由 16 种不同的复合板组成的综合套件，包括未增强的板、用 MWCNT 增强的板、用 PA 6.6 增强的板以及用 PA 6.6 和 MWCNT 的组合增强的板 （PA 6.6-MWCNT）。研究了在 20、40 和 60 J 能级下生产的复合板的冲击强度。详细研究了用 MWCNTs、PA 6.6 和 PA 6.6-MWCNTs 增强复合结构以及功能分级 KF/CF 对冲击强度的影响。通过检查高分辨率相机和光学显微镜图像来解释由于低速冲击测试而对材料造成的损坏。因此，将纳米纤维和纳米颗粒对复合结构的增强和杂化效果一起评价。在 PA 6.6、MWCNT 和 PA 6 的增强下。6-MWCNTs，纳米复合材料样品的冲击强度与未增强样品相比显著提高。此外，低速冲击试验对增强样品造成的损伤量显著减少。