今日更新:Composite Structures 1 篇,Composites Part A: Applied Science and Manufacturing 1 篇,Composites Part B: Engineering 1 篇
CONFINEMENT OF MASONRY WITH FRCM COMPOSITES: STRENGTH PREDICTIVE MODELS
Annalisa Napoli, Roberto Realfonzo
doi:10.1016/j.compstruct.2023.117864
用 FRCM 复合材料对砌体进行约束:强度预测模型
Fabric reinforced cementitious matrix (FRCM) composites have emerged as an appealing alternative to fiber reinforced polymer (FRP) for the external confinement of masonry members; nevertheless, their use in practice is limited due to the lack of reliable formulas to estimate the compressive strength and ultimate strain of confined members. By following a recently published study, new formulas for the prediction of the compressive strength of the FRCM confined masonry are proposed here, which were obtained by considering an updated experimental database compiled from the literature. These formulas were developed by applying error minimization techniques to the collected experimental results; test data were treated in different ways, such as: a) separating the members made of natural stones from those built with artificial blocks, and b) treating separately the fiber types (basalt, carbon, glass, PBO and steel) of the FRCM system, or c) considering the experimental data all together. Finally, to evaluate the reliability of the developed relationships, the strength predictions provided by the new proposals were compared with those obtained using the expressions reported in some international guidelines.
织物增强水泥基复合材料(FRCM)已成为纤维增强聚合物(FRP)的替代品,可用于砌体的外部约束;然而,由于缺乏可靠的公式来估算约束构件的抗压强度和极限应变,它们在实践中的应用受到了限制。根据最近发表的一项研究,本文提出了用于预测 FRCM 封闭砌体抗压强度的新公式,这些公式是通过考虑文献中汇编的最新实验数据库而获得的。这些公式是通过对收集到的实验结果应用误差最小化技术而得出的;测试数据采用了不同的处理方式,例如:a) 将天然石块和人工砌块制成的构件分开处理;b) 将 FRCM 系统的纤维类型(玄武岩、碳、玻璃、PBO 和钢)分开处理;或者 c) 将所有实验数据放在一起考虑。最后,为了评估所建立关系的可靠性,将新建议提供的强度预测值与使用一些国际指南中报告的表达式获得的强度预测值进行了比较。
The effect of fibre misalignment in an impregnated fibre bundle on stress concentrations
M. Jafarypouria, S.V. Lomov, Biltu Mahato, S.G. Abaimov
doi:10.1016/j.compositesa.2023.108001
浸渍纤维束中纤维错位对应力集中的影响
This work investigates the stress redistribution around a broken fibre in a unidirectional impregnated fibre bundle accounting for misalignment of fibres. The study reveals, a statistically significant increase in stress concentration factor (SCF) within misaligned bundles. The effect of fibre misalignment is more pronounced for high fibre volume fraction (VF) and for the nearest neighbour fibres (NNFs) to the broken one. The peak of the SCF graphs shows a significant increase about 16%, 33%, and 55% for VF30%, VF50%, and VF60%, respectively. This implies that the influence of fibre misalignment is more localised, resulting in stronger SCF in the NNFs. Ineffective lengths at applied strain 2% do not change in the case of fibre misalignment in comparison with the case of aligned fibres. This is linked to matrix yielding, as at applied strain 0.1% the ineffective length increases for the misaligned case by 12-30%, depending of fibre volume fraction.
这项研究探讨了单向浸渍纤维束中断裂纤维周围的应力再分布,并考虑了纤维错位的情况。研究发现,在错位纤维束中,应力集中系数(SCF)在统计学上有显著增加。纤维错位对高纤维体积分数(VF)和断裂纤维的近邻纤维(NNF)的影响更为明显。在 VF30%、VF50% 和 VF60% 时,SCF 图形的峰值分别显著增加了约 16%、33% 和 55%。这意味着纤维错位的影响更加局部化,导致 NNF 的 SCF 更强。与纤维对齐的情况相比,纤维错位情况下施加应变 2% 时的无效长度没有变化。这与基体屈服有关,因为在施加应变 0.1% 时,错位情况下的无效长度增加了 12-30%,具体取决于纤维的体积分数。
Tailoring nanostructured MXene to adjust its dispersibility in conductive hydrogel for self-powered sensors
Yaoxun Zhang, Jian Zou, Shengji Wang, Xiangshu Hu, Zihao Liu, Peiyong Feng, Xin Jing, Yuejun Liu
doi:10.1016/j.compositesb.2024.111191
定制纳米结构 MXene 以调整其在导电水凝胶中的分散性,用于自供电传感器
MXenes are ideal conductive fillers to construct conductive routes for hydrogel-based flexible sensors owing to their great metallic conductivity, hydrophilicity, and high specific surface area. However, their high tendency to aggregate in sol solution severely limited the performance of the resultant hydrogels. Therefore, to enhance the performance of MXene-filled composite hydrogels, we proposed an oxidization method to tailor the nanostructure of MXene to improve the conductivity, transparency, mechanical properties, and sensitivity of the composite hydrogels. Meanwhile, it is noted that the conductivity of the hydrogel significantly affected the output performance of hydrogel-based triboelectric nanogenerator (H-TENG). The polyacrylamide/oxidized MXene (POM) hydrogel-based TENG with the highest output performance was assembled for self-powered sensing and energy harvesting, which demonstrated great reliability and durability with a maximum open circuit voltage of 243 V and a peak power density of 2.38 W/m2. Moreover, the relationship model between the conductivity of the hydrogel and the output performance of the H-TENG was successfully proposed based on the performance of the developed H-TENGs. Therefore, this work shed lights for reasonable design of H-TENGs with high output performance.
二甲氧烯类具有极强的金属导电性、亲水性和高比表面积,是构建基于水凝胶的柔性传感器导电路径的理想导电填料。然而,它们在溶胶溶液中的高聚集倾向严重限制了生成的水凝胶的性能。因此,为了提高 MXene 填充复合水凝胶的性能,我们提出了一种氧化方法来定制 MXene 的纳米结构,从而提高复合水凝胶的导电性、透明度、机械性能和灵敏度。同时,我们注意到水凝胶的电导率会显著影响水凝胶基三电纳米发电机(H-TENG)的输出性能。研究人员组装了输出性能最高的聚丙烯酰胺/氧化二甲苯(POM)水凝胶基三电纳米发电机,用于自供电传感和能量收集,其最大开路电压为 243 V,峰值功率密度为 2.38 W/m2,表现出极高的可靠性和耐用性。此外,根据所开发 H-TENG 的性能,成功地提出了水凝胶电导率与 H-TENG 输出性能之间的关系模型。因此,这项工作为合理设计具有高输出性能的 H-TENG 提供了启示。