今日更新:Composites Part B: Engineering 1 篇,Composites Science and Technology 1 篇
The relationship between the impact position interference and CAI strength of composite sandwich structures under double impacts
Zhu Keyu, Zheng Xitao, Peng Jing, Sun Jiaming, Huang Ruilin, Yan Leilei
doi:10.1016/j.compositesb.2023.111092
复合材料夹层结构在双重冲击下的冲击位置干扰与 CAI 强度之间的关系
Sandwich structures are susceptible to multiple-impacts, and such multiple-impacts will typically occur at certain distances from each other. Therefore, the influence of five different distances between impact positions (DBIP) and three impact energies on compression after impact (CAI) strength are considered and discussed for honeycomb sandwich structure with composite face sheets in this paper. By comparing two typical impact characteristics, i.e., maximum impact force and displacement, the trend of CAI strength shows a turning-point, which is closely related to the size of the impactor. However, high impact energy (15 J) leads to damage in the bottom face sheet during the second impact, and the presence of damage in both top and bottom face sheet reduces CAI strength, resulting in the turning point of CAI strength not exist. It was observed that there is obvious buckling failure, and some cracks along the width direction from the impact point to the edge after CAI. To provide a more comprehensive understanding of double impacts and CAI behavior, a finite element (FE) model considering different DBIP is developed. In addition, the predicted fraction of energy absorbed by top face sheet, honeycomb core, and bottom face sheet is also obtained to reveal the relationship between the impact position interference and CAI strength.
夹层结构容易受到多重撞击,而这种多重撞击通常会在一定距离内发生。因此,本文考虑并讨论了五种不同冲击位置间距(DBIP)和三种冲击能量对复合材料面片蜂窝夹层结构冲击后压缩强度(CAI)的影响。通过比较两种典型的冲击特性,即最大冲击力和位移,CAI 强度的变化趋势出现了一个转折点,这与冲击器的大小密切相关。然而,高冲击能量(15 J)会导致底部面板在第二次冲击时出现损坏,而顶部和底部面板的损坏都会降低 CAI 强度,从而导致 CAI 强度转折点不存在。据观察,CAI 后出现了明显的屈曲破坏,并且从冲击点到边缘沿宽度方向出现了一些裂纹。为了更全面地了解双重撞击和 CAI 行为,建立了一个考虑不同 DBIP 的有限元(FE)模型。此外,还获得了顶部面板、蜂窝芯和底部面板吸收能量的预测比例,从而揭示了撞击位置干涉与 CAI 强度之间的关系。
Optically transparent and high-strength glass-fabric reinforced composite
Yishan Yang, Yukang Lai, Song Zhao, Hongguang Chen, Renshu Li, Wang Yongjiang
doi:10.1016/j.compscitech.2023.110338
光学透明高强度玻璃纤维增强复合材料
Fiber reinforced polymer composites (FRPs) are widely utilized in various industrial applications due to their significant advantages such as low cost and superior mechanical properties. However, owing to the trade-off between high mechanical strength and high optical transparency with typical FRPs, it is technically challenging to achieve high mechanical performance while meeting the optical requirements for transparent electronics and automotive applications. We herein report the synthesis of a transparent fiber reinforced polymer (tGFRP) by incorporating reinforced E-glass fiber into refractive-index-tunable thermosetting epoxy resin and the consequential advantageous opto-mechanical properties. By doping organic molecules, the optical property of the epoxy-based resin system has been efficiently engineered, achieving the match of the chromatic dispersions of the E-glass fiber and the epoxy resin. By the means of a novel technique derived from infusion treatment and in-situ polymerization combined with a liquid composite molding (LCM) method, both surface and bulk defects have been efficiently mitigated. With the refractive-index of the epoxy matrix matched with that of the embedded fiber fabrics, high transparency up to 88% has been realized with 10v.% fiber loading (500μm thick tGFRP). An outstanding transparency and superior mechanical properties were achieved on 2mm thick samples, maintaining up to 85% transmittance even when using 25 layers of E-glass fabric, corresponding to 50 v.% fiber. This work has shed light on the development of transparent composite materials for applications such as in construction, transportation, and protective equipment.
纤维增强聚合物复合材料(FRP)具有成本低、机械性能优异等显著优势,被广泛应用于各种工业领域。然而,由于典型的玻璃纤维增强聚合材料需要在高机械强度和高光学透明度之间进行权衡,因此在满足透明电子产品和汽车应用的光学要求的同时实现高机械性能在技术上具有挑战性。我们在此报告通过将增强 E 玻璃纤维加入折射率可调的热固性环氧树脂,合成了一种透明纤维增强聚合物(tGFRP),并由此获得了有利的光学机械性能。通过掺杂有机分子,环氧树脂体系的光学性能得到了有效的改善,实现了玻璃纤维和环氧树脂色散的匹配。通过一种源自导流处理和原位聚合的新技术,并结合液态复合材料成型(LCM)方法,有效地减少了表面和体积缺陷。由于环氧树脂基体的折射率与嵌入的纤维织物的折射率相匹配,因此在纤维含量为 10v.% 时(tGFRP 厚度为 500μm),透明度高达 88%。在 2 毫米厚的样品上,即使使用 25 层 E 玻璃纤维织物(相当于 50 v.% 的纤维),也能保持高达 85% 的透光率,实现了出色的透明度和卓越的机械性能。这项工作为透明复合材料的开发提供了启示,可应用于建筑、运输和防护设备等领域。