今日更新:Composite Structures 3 篇,Composites Part A: Applied Science and Manufacturing 3 篇,Composites Science and Technology 3 篇
Experimental Investigation on Impact Behavior of Curved Sandwich Composites with Chiral Auxetic Core
Dilek ATİLLA YOLCU, Buket OKUTAN BABA
doi:10.1016/j.compstruct.2023.117749
带有手性助剂芯材的曲面三明治复合材料冲击行为的实验研究
The purpose of this study is to evaluate and compare the capability of impact energy absorption of the sandwich panels with various chiral auxetic cores. To this end, flat and curved panels were subjected to impact testing at varying energy levels. Glass fiber-reinforced epoxy composites and PLA material were used as the skins and core of the examined sandwich panels, respectively. The face sheets were produced by the hand-layup method and the auxetic cores with tetrachiral, anti-tetrachiral, and hexachiral configurations were printed using a 3D printer. The wall thickness, node diameter, and ligament length of the cells, as well as the core thickness, were kept constant for all the studied core structures. Flat and curved sandwich panels were obtained by combining the skins and cores produced in flat, 100 mm, 125 mm, and 160 mm radii of curvature with the epoxy used in skin production. Drop weight tests were carried out at impact energies of 10, 25, and 80 J. The contribution of the auxetic core configuration and panel curvature to the impact behavior of the sandwich panel was evaluated by examining the relationships between contact forces and deflection and by the analysis of the energy absorption and failure mode. The comparative evaluations showed that the auxetic core structure and the curvature of the panel have a significant effect on the impact properties of the sandwich panels. It was also observed that the use of tetrachiral cores could be the ideal design option for flat panels loaded at the perforation energy level. For curved panels, it was determined that the use of a hexachiral core configuration was advantageous in terms of more energy absorption capability, while the use of an anti-tetrachiral core structure was more effective in terms of specific energy absorption.
本研究的目的是评估和比较带有各种手性助剂芯材的夹芯板的冲击能量吸收能力。为此,对平板和曲面板进行了不同能量水平的冲击测试。玻璃纤维增强环氧树脂复合材料和聚乳酸材料分别用作受测夹层板的表皮和芯材。面板采用手糊法制作,而四旋翼、反四旋翼和六旋翼结构的助剂芯材则使用三维打印机打印。在所有研究的芯结构中,细胞的壁厚、节点直径和韧带长度以及芯厚度都保持不变。通过将以平面、100 毫米、125 毫米和 160 毫米曲率半径生产的表皮和芯材与表皮生产中使用的环氧树脂相结合,获得了平面和曲面夹层板。通过检查接触力和挠度之间的关系以及分析能量吸收和失效模式,评估了辅助夹芯结构和面板曲率对夹芯板冲击行为的影响。比较评估结果表明,磁芯结构和面板曲率对夹芯板的冲击性能有显著影响。同时还发现,对于以穿孔能量水平加载的平板,使用四螺旋芯材是理想的设计方案。对于弧形面板,使用六螺旋夹芯结构具有更强的能量吸收能力,而使用反四螺旋夹芯结构则能更有效地吸收特定能量。
Quasi-static mechanical behavior of 2.5D woven variable thickness composites
Nan Wang, Weidong Wen, Yipeng Chang, Yu Zhou, Konghan Lu, Hongjian Zhang
doi:10.1016/j.compstruct.2023.117759
2.5D 可变厚度编织复合材料的准静态力学行为
Many special-shaped structural parts have begun to be prepared in aerospace and other fields using 2.5D woven composites. Therefore, two kinds of 2.5D woven variable-thickness composites are designed by reducing the number of yarn layers, called outer reduction yarn woven composites (ORYWC) and inner reduction yarn woven composites (IRYWC). Both variable thickness regions comprise five independent parts, each occupying one or two layers of yarn reduction. In addition, the microstructure of ORYWC and IRYWC is measured using X-ray computed tomography, and the mechanism of geometric deformation during weaving and molding is discussed. Finally, the quasi-static tensile test is conducted to compare and analyze the longitudinal stiffness, tensile strength, and damage mechanism of ORYWC and IRYWC. The results show that the longitudinal stiffness of the five parts of the two structures maintains little difference. The average stiffness and tensile strength of IRYWC decrease by 4.82% and 10.65% compared with ORYWC.
航空航天和其他领域已开始使用 2.5D 编织复合材料制备许多异形结构件。因此,通过减少纱线层数设计出了两种 2.5D 编织变厚度复合材料,分别称为外减纱编织复合材料(ORYWC)和内减纱编织复合材料(IRYWC)。这两种可变厚度区域都由五个独立部分组成,每个部分占据一层或两层还原纱。此外,还使用 X 射线计算机断层扫描技术测量了 ORYWC 和 IRYWC 的微观结构,并讨论了编织和成型过程中几何变形的机理。最后,进行了准静态拉伸试验,以比较和分析 ORYWC 和 IRYWC 的纵向刚度、抗拉强度和损伤机理。结果表明,两种结构五个部分的纵向刚度差别不大。与 ORYWC 相比,IRYWC 的平均刚度和抗拉强度分别降低了 4.82% 和 10.65%。
Optimal design of composite sandwich panel with auxetic reentrant honeycomb using asymptotic equivalent model and PSO algorithm
Peng Xiao, Lei Bin, Riccardo Vescovini, Shi Zheng
doi:10.1016/j.compstruct.2023.117761
利用渐近等效模型和 PSO 算法优化带有辅助再入蜂窝的复合夹芯板的设计
The composite honeycomb sandwich with auxetic reentrant honeycomb (CSP-ARH) is a typical negative Poisson’s ratio structure, which has better mechanical properties than composite structure with positive Poisson’s ratio. In this study, a 2D asymptotic equivalent model (AEM) based on the variational asymptotic method (VAM) is proposed and used to analyze the vibration and buckling problems of CSP-ARH incorporating CFRP facesheets and an aluminum honeycomb core. After validation with 3D finite element results, a particle swarm optimization (PSO) algorithm is applied to optimize the mesoscopic size of composite facesheets and honeycomb core. The primary objectives of the optimization process involve maximizing the buckling load and natural frequency, minimizing the mass while satisfying specific mechanical properties requirements. Moreover, a few additional optimization iterations are performed to find the optimal shape coefficients of the curved fibers in the CFRP facesheets for variable stiffness composite sandwich panels. The shape of the curved fiber is defined using a cubic polynomial function f(x,y) and is described by a 20 × 20 grid of discrete elements. The results indicate that CSP-ARH with optimal curved fibers shapes exhibit superior performance compared to those with straight fibers, with buckling load and natural frequency increased by 8.18% and 7.09%, respectively.
带辅助再入蜂窝的复合蜂窝夹层(CSP-ARH)是一种典型的负泊松比结构,与正泊松比复合结构相比具有更好的力学性能。本研究提出了一种基于变异渐近法(VAM)的二维渐近等效模型(AEM),用于分析包含 CFRP 面板和铝蜂窝芯的 CSP-ARH 的振动和屈曲问题。经三维有限元结果验证后,采用粒子群优化(PSO)算法对复合材料面片和蜂窝芯的中观尺寸进行优化。优化过程的主要目标包括最大化屈曲载荷和固有频率,最小化质量,同时满足特定的机械性能要求。此外,还进行了一些额外的优化迭代,以找到 CFRP 面板中弯曲纤维的最佳形状系数,从而实现可变刚度复合材料夹芯板。弯曲纤维的形状使用三次多项式函数 f(x,y) 来定义,并用 20 × 20 的离散元素网格来描述。结果表明,采用最佳弯曲纤维形状的 CSP-ARH 与采用直纤维的 CSP-ARH 相比性能更优,屈曲载荷和固有频率分别提高了 8.18% 和 7.09%。
Clarifying the mechanisms of edge glow generation in CFRP laminates exposed to simulated lightning currents
Shintaro Kamiyama, Takao Okada, Yoshiyasu Hirano, Takeo Sonehara, Hiromitsu Miyaki, Toshio Ogasawara
doi:10.1016/j.compositesa.2023.107932
阐明暴露在模拟雷电流中的 CFRP 层压板边缘辉光的产生机制
This study examines edge glow mechanisms of CFRP laminates exposed to simulated lightning current by performing direct electrical conduction tests. An impulse electric current, in accordance with SAE ARP 5412B, was applied to the laminates. Numerical simulations based on finite element analysis (FEA) were performed to clarify the voltage and temperature distributions of the CFRP laminates. The analytical results were validated using the experimentally obtained I–V characteristics and temperature responses. Resultingly, edge glow was observed in quasi-isotropic but not in unidirectional and cross-ply laminates. The edge glow was suppressed more in silicone oil than in air. When the edge glow did not occur, the numerical simulation results, I–V characteristics, and temperature response, exhibited good agreement with the experimentally obtained results. Contrary to Joule heating, potential differences of several hundred volts between each layer, which cause dielectric breakdown in the testing atmosphere, are the criterion for edge glow formation.
本研究通过直接电导测试,研究了暴露在模拟雷电流下的 CFRP 层压板的边缘发光机制。根据 SAE ARP 5412B 标准,对层压板施加了脉冲电流。在有限元分析(FEA)的基础上进行了数值模拟,以明确 CFRP 层压板的电压和温度分布。分析结果通过实验获得的 I-V 特性和温度响应进行了验证。结果发现,准各向同性层压板出现了边缘辉光,而单向层压板和交叉层压板则没有。边缘辉光在硅油中比在空气中更容易被抑制。当边缘辉光没有出现时,数值模拟结果、I-V 特性和温度响应与实验结果显示出良好的一致性。与焦耳加热相反,每层之间几百伏的电位差是边缘辉光形成的标准,这种电位差会导致测试气氛中的介电击穿。
Intrinsically conductive resin as a functional repair for ECF/CFRP against simulated lighting strike: an experimental study
Li Xiaodong, Yu Zhou, Shintaro Kamiyama, Takao Okada, Tomohiro Yokozeki
doi:10.1016/j.compositesa.2023.107933
本征导电树脂作为 ECF/CFRP 的功能性修复材料,可抵御模拟照明冲击:一项实验研究
Non-metallic coatings offer promising applications for protecting carbon fiber-reinforced plastics (CFRP) from lightning, preserving the strengths of epoxy-based composites without galvanic corrosion concerns. This study explores the electrically conductive polyaniline-based resin's dual role: as protective coating and repair solution for traditional ECF/CFRP lightning protection. We evaluated the impact of coating thickness and surface roughness on lightning resistance. A 0.4mm thick coating with a 400-grit pretreatment demonstrated minimal damage after a -40kA simulated lightning strike, maintaining 96% residual strength. Central to this study was the resin's capability as a functional repair for the conventional ECF LSP system. When employed to repair the damaged ECF/CFRP panel, the resin showcased its efficacy by preserving more than 95% of the system's residual strength even after a subsequent -20kA lightning strike. These results indicate the proposed conductive resin could be a new practical repair approach for lightning strike damage to the conventional ECF layer.
非金属涂料在保护碳纤维增强塑料(CFRP)免受雷击方面具有广阔的应用前景,既能保持环氧基复合材料的强度,又不会产生电化学腐蚀问题。本研究探讨了导电聚苯胺基树脂的双重作用:作为传统 ECF/CFRP 防雷保护的保护涂层和修复解决方案。我们评估了涂层厚度和表面粗糙度对抗雷性的影响。经过 400 砂粒预处理的 0.4 毫米厚涂层在遭受 -40kA 模拟雷击后显示出最小的损坏率,并保持了 96% 的残余强度。这项研究的核心是树脂作为传统 ECF LSP 系统功能性修复的能力。当使用该树脂修复受损的 ECF/CFRP 面板时,即使在随后的 -20kA 雷击后,该树脂仍能保持系统 95% 以上的剩余强度,充分展示了其功效。这些结果表明,所提出的导电树脂可以成为一种新的实用修复方法,用于修复传统 ECF 层的雷击损坏。
Estimation of the moisture absorption rate of carbon fiber reinforced plastic using electromagnetic induction testing
Wataru Matsunaga, Satoshi Imai, Yoshihiro Mizutani, Tetsuo Yasuoka, Akira Todoroki
doi:10.1016/j.compositesa.2023.107934
利用电磁感应测试估算碳纤维增强塑料的吸湿率
Because moisture absorption changes the permittivities and electrical conductivities of carbon fiber reinforced plastics (CFRPs) with resin layers, electromagnetic induction testing (EIT) was used for evaluating CFRP moisture absorption. Conductivity and permittivity changes were obtained using a finite element analysis (FEA). A moisture-absorption test was conducted to deduce the relationship between the conductivity and moisture-absorption rate. The conductivity corresponding to CFRP moisture absorption was calculated and used in the FEA, while the permittivity corresponding to CFRP moisture absorption was numerically calculated. The simulation suggested that, as CFRPs absorbed moisture, the influence of displacement currents dominated in the EIT output. Finally, CFRP moisture absorption was analyzed using EIT. The results indicated that the EIT output tended to increase with moisture absorption, indicating the dominance of the displacement-current change due to resin moisture absorption in the moisture absorption. These results demonstrate the effectiveness of EIT for evaluating CFRP moisture absorption.
由于吸湿会改变带树脂层的碳纤维增强塑料(CFRP)的介电常数和导电率,因此采用了电磁感应测试(EIT)来评估 CFRP 的吸湿情况。电导率和介电常数的变化是通过有限元分析(FEA)获得的。为了推断电导率和吸湿率之间的关系,还进行了吸湿测试。有限元分析计算并使用了与 CFRP 吸湿率相对应的电导率,同时数值计算了与 CFRP 吸湿率相对应的介电常数。模拟结果表明,随着 CFRP 吸湿,位移电流的影响在 EIT 输出中占主导地位。最后,使用 EIT 分析了 CFRP 吸湿情况。结果表明,EIT 输出随着吸湿量的增加而增加,表明树脂吸湿引起的位移电流变化在吸湿量中占主导地位。这些结果证明了 EIT 在评估 CFRP 吸湿性方面的有效性。
Highly conductive and mechanically robust MXene@CF core-shell composites for in-situ damage sensing and electromagnetic interference shielding
Yi Hu, Junzhen Chen, Guoyu Yang, Yujun Li, Ming Dong, Han Zhang, Emiliano Bilotti, Jianjun Jiang, Dimitrios G. Papageorgiou
doi:10.1016/j.compscitech.2023.110356
用于原位损伤传感和电磁干扰屏蔽的高导电性和机械坚固性 MXene@CF 核壳复合材料
In this work, a new type of carbon fiber reinforced polymer (CFRP) composite was fabricated by introducing MXene nanoparticles onto the surface of carbon fibers (CF) via electrophoretic deposition (EPD) followed by thermal annealing. The MXene-reinforced CF/epoxy composites displayed enhanced mechanical properties and electrical conductivity as well as in-situ damage sensing capability. The uniformly deposited MXene nanoparticles contributed to a considerable enhancement of the flexural strength of CFRPs through hydrogen bonding and mechanical interlocking. The thermal annealing treatment reduced the amount of oxygen groups on the surface of MXene nanoparticles and enabled a 66 % increase of the out-of-plane electrical conductivity and a 20 % improvement of the electromagnetic interference (EMI) shielding effectiveness. The exceptional EMI performance of the core-shell hierarchical microstructure can be ascribed to the polarization of the inhomogeneous interfaces, the dipole polarization, and the conductive loss effect as a result of the presence of annealed MXenes on the surface of CFs.
在这项工作中,通过电泳沉积(EPD)在碳纤维(CF)表面引入 MXene 纳米粒子,然后进行热退火,制备了一种新型碳纤维增强聚合物(CFRP)复合材料。MXene 增强 CF/epoxy 复合材料显示出更强的机械性能、导电性和原位损伤传感能力。均匀沉积的 MXene 纳米粒子通过氢键和机械互锁作用大大提高了 CFRP 的抗弯强度。热退火处理减少了 MXene 纳米粒子表面的氧基团数量,使平面外导电率提高了 66%,电磁干扰(EMI)屏蔽效果提高了 20%。核壳分层微结构优异的电磁干扰性能可归因于非均质界面的极化、偶极子极化和导电损耗效应,这些都是 CF 表面存在退火 MXenes 的结果。
Nucleation and property enhancement mechanism of robust and high-barrier PLA/CNFene composites with multi-level reinforcement structure
Ling Yan, Somia Yassin Hussain Abdalkarim, Xuefei Chen, ZhiMing Chen, Weidong Lu, Jingli Zhu, Meijin Jin, Hou-Yong Yu
doi:10.1016/j.compscitech.2023.110364
具有多级增强结构的强韧高阻隔聚乳酸/CNFene 复合材料的成核与性能增强机理
The demand for biopolymer-based green packaging has attracted growing attention because of its outstanding properties and consistency with clean environmental principle, unfortunately, its slow crystallization rate and narrow processing window is challenging. Inspired by combined functions in nanocellulose-based conductive hybrids, this work developed high-performance polylactic acid (PLA) composites using conductive cellulose nanofiber (CNFene). Interestingly, CNFene has multiple functions as highly graphitized carbon and abundant hydroxyl groups, delivering stimulating properties to PLA composites. As nucleating agents, 3wt% CNFene has a carbon layer on the surface combined with a hydrogen bonding network synergistically enhancing the tensile and crystallization properties of PLA-C3, with a tensile strength of ∼ 53.7 MPa, crystallinity of ∼ 33.9 %, and 6.6 °C decrease in the cold crystallization temperature. Additionally, the compatibility between CNFene and PLA can form a multi-level “reinforcement” network structure, further improving thermal stability and barrier properties. The resultant PLA-C3 showed higher thermal decomposition onset temperature(T0), wider melt-processing window (197.6 °C) and extremely lower overall migration levels in ethanol (68.6 μg/kg) and isooctane (16.3 μg/kg), due to that improved interaction between CNFene and PLA positively affects crystallization ability and kinetic/mechanism of PLA to meet the requirements of industrial and green biopackaging applications.
基于生物聚合物的绿色包装因其出色的性能和符合清洁环保原则而受到越来越多的关注,遗憾的是,其缓慢的结晶速度和狭窄的加工窗口是一项挑战。受基于纳米纤维素的导电混合材料综合功能的启发,本研究利用导电纳米纤维素(CNFene)开发了高性能聚乳酸(PLA)复合材料。有趣的是,CNFene 具有高度石墨化碳和丰富羟基的多重功能,可为聚乳酸复合材料提供刺 激特性。作为成核剂,3wt% CNFene 表面的碳层与氢键网络相结合,协同增强了聚乳酸-C3 的拉伸和结晶性能,使其拉伸强度达到 ∼ 53.7 MPa,结晶度达到 ∼ 33.9 %,冷结晶温度降低了 6.6 °C。此外,氯化萘与聚乳酸的相容性可形成多层次的 "增强 "网络结构,进一步提高热稳定性和阻隔性能。所制备的聚乳酸-C3 具有更高的热分解起始温度(T0)、更宽的熔融加工窗口(197.6 °C)以及在乙醇(68.6 μg/kg)和异辛烷(16.3 μg/kg)中更低的整体迁移水平,这是因为改进的氯化萘与聚乳酸之间的相互作用对聚乳酸的结晶能力和动力学/机理产生了积极影响,从而满足了工业和绿色生物包装应用的要求。
Enhancing impact resistance of hybrid structures designed with triply periodic minimal surfaces
Fenglei Li, Jiakang Gan, Long Zhang, Hailun Tan, Eric Li, Bing Li
doi:10.1016/j.compscitech.2023.110365
增强采用三周期极小表面设计的混合结构的抗冲击性
The triply periodic minimal surface (TPMS) represents an engineered structure characterized by its mathematically controllable geometric topology and exceptional mechanical properties. This structure offers notable features such as high porosity, specific strength, stiffness, and energy absorption capabilities. Drawing inspiration from the structure of the human tibia, we developed hybrid structures that combine side-by-side, circular, and elliptical connections, utilizing two TPMS types: IWP and Gyroid. Our comprehensive study delves into the impact resistance of these hybrid structures when subjected to high strain rate loading. To conduct our research, we employed selective laser melting (SLM) to fabricate TPMS samples based on AlSi10Mg, and we validated our finite element model through quasi-static compression experiments. By conducting numerical simulations, we analyzed the mechanical properties and deformation patterns of these structures under strain rates of 250 s−1 and 1250 s−1, comparing them to commonly used porous structures such as Honeycomb, FCC, and BCC. Through quantitative analysis utilizing various evaluation indexes, we effectively demonstrated how the design of hybrid structures enhances energy absorption. Furthermore, we discussed the impact of strain rate on the mechanical properties of these structures, and the Gibson-Ashby model accurately predicted the mechanical properties of partial structures. These findings hold significant implications for guiding the design of lightweight porous structures, improving energy absorption, and enhancing impact resistance.
三周期极小表面(TPMS)是一种工程结构,其特点是具有数学可控的几何拓扑结构和优异的机械性能。这种结构具有高孔隙率、比强度、刚度和能量吸收能力等显著特点。我们从人类胫骨的结构中汲取灵感,利用两种 TPMS 类型,开发出了结合并排、圆形和椭圆形连接的混合结构: IWP 和 Gyroid。我们的综合研究深入探讨了这些混合结构在承受高应变率加载时的抗冲击性。为了开展研究,我们采用选择性激光熔融(SLM)技术制造了基于 AlSi10Mg 的 TPMS 样品,并通过准静态压缩实验验证了我们的有限元模型。通过进行数值模拟,我们分析了这些结构在 250 s-1 和 1250 s-1 应变速率下的机械性能和变形模式,并将其与蜂窝、FCC 和 BCC 等常用多孔结构进行了比较。通过利用各种评价指标进行定量分析,我们有效地展示了混合结构的设计如何增强能量吸收。此外,我们还讨论了应变率对这些结构的机械性能的影响,吉布森-阿什比模型准确地预测了部分结构的机械性能。这些发现对于指导轻质多孔结构的设计、改善能量吸收和增强抗冲击性具有重要意义。