Wang Mingling, Pan Zhongxiang, Cai Qimao, Zhao Lei, Wu Zhenyu
Faculty of Mechanical Engineering, Zhejiang Sci-Tech University, Hangzhou 310018, China.
College of Textile Science and Engineering, Zhejiang Sci-Tech University, Hangzhou 310018, China.
Polymers (Basel). 2024 Jun 25;16(13):1801. doi: 10.3390/polym16131801.
The investigation of damage development is essential for the design and optimization of hybrid structures. This paper provides a reference for the structural design of brittle-ductile hybrid LVI-resistant laminates through analyzing the damage development mechanism of carbon/Kevlar fabric-reinforced composite laminates. The effects of Kevlar fabric hybrid ply and intercalation on the damage development of carbon/Kevlar composite laminates under low-velocity impact (LVI) were investigated using quasi-static indentation (QSI). It was found that an increase in the Kevlar hybrid ratio significantly reduced the peak load and stiffness of these laminates (the maximum decreases in strength and stiffness were 46.03% and 41.43%, respectively), while laminates with identical hybrid ratios but different plying configurations maintained a comparable stiffness under QSI, with differences of less than 5%. Interestingly, Kevlar fibers exhibited irregular fractures as the yarn was splitting, while carbon fibers presented neat breaks, which indicated material-specific failure modes. Notably, the introduction of Kevlar hybridization beyond pure Kevlar configurations (KKKK) resulted in a decrease in the percentage of fiber damage (CCCC, CCCK, CCKK, and KCCK accounted for 80%, 79.8%, 70%, and 60% of fiber damage, respectively), attributed to an increase in resin cracks and lower levels of Kevlar yarn breakage. The internal damage diameter of specimens was accurately predicted from the diameter of visible damage on the QSI surface. Compared with CCCC and CCKK setups, which are affected by resin cracks formed via the carbon surface on the loading side propagating along the yarn direction (including the yarn settling direction), KCCK demonstrated less delamination between the first and second ply.
损伤发展的研究对于混合结构的设计和优化至关重要。本文通过分析碳/芳纶织物增强复合层压板的损伤发展机制，为脆性-韧性混合抗低速冲击层压板的结构设计提供了参考。采用准静态压痕（QSI）研究了芳纶织物混杂层和插层对碳/芳纶复合层压板在低速冲击（LVI）下损伤发展的影响。研究发现，芳纶混杂比例的增加显著降低了这些层压板的峰值载荷和刚度（强度和刚度的最大降幅分别为46.03%和41.43%），而具有相同混杂比例但不同铺层配置的层压板在QSI下保持了相当的刚度，差异小于5%。有趣的是，芳纶纤维在纱线分裂时呈现不规则断裂，而碳纤维则呈现整齐断裂，这表明了材料特定的失效模式。值得注意的是，与纯芳纶配置（KKKK）相比，引入芳纶混杂导致纤维损伤百分比降低（CCCC、CCCK、CCKK和KCCK分别占纤维损伤的80%、79.8%、70%和60%），这归因于树脂裂纹的增加和芳纶纱线断裂水平的降低。根据QSI表面可见损伤的直径准确预测了试样的内部损伤直径。与受加载侧碳表面形成的树脂裂纹沿纱线方向（包括纱线沉降方向）扩展影响的CCCC和CCKK设置相比，KCCK在第一层和第二层之间的分层较少。
