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【新文速递】2023年12月5日复合材料SCI期刊最新文章

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今日更新:Composite Structures 5 篇,Composites Part B: Engineering 1 篇

Composite Structures

A review of prediction methods for global buckling critical loads of pultruded FRP struts

Hengming Zhang, Feng Li

doi:10.1016/j.compstruct.2023.117752

拉挤玻璃钢支柱全局屈曲临界载荷预测方法综述

Pultruded fiber-reinforced composites (FRP) are widely used in structural engineering due to their excellent properties along the fiber direction. Its global buckling performance has received increasing attention from academia and engineering. This paper reviews the prediction methods for the critical buckling load of pultruded FRP struts, including the Euler formula critical load prediction method, the shear-corrected critical load prediction method, the Southwell plot method, and the critical load prediction method based on the strength failure mode. Summarizes the basic principles of each method, discusses the internal relationship and difference of each method, and analyzes the critical factors of each method with experimental data. In addition, a unified generalized Ayton-Perry theoretical model is proposed through induction and summary. Finally, based on the experimental database, a Machine learning model for predicting the buckling critical load is established. The results show that the machine learning algorithm can predict the buckling critical load with high prediction accuracy.

拉挤纤维增强复合材料(FRP)因其沿纤维方向的优异性能而被广泛应用于结构工程中。其整体屈曲性能越来越受到学术界和工程界的关注。本文综述了拉挤玻璃钢支柱临界屈曲载荷的预测方法,包括欧拉公式临界载荷预测法、剪切校正临界载荷预测法、Southwell plot 法和基于强度失效模式的临界载荷预测法。总结了每种方法的基本原理,讨论了每种方法的内在关系和区别,并结合实验数据分析了每种方法的关键因素。此外,通过归纳和总结,提出了统一的广义艾顿-佩里理论模型。最后,基于实验数据库,建立了预测屈曲临界载荷的机器学习模型。结果表明,机器学习算法能以较高的预测精度预测屈曲临界载荷。


Explicit analytical solutions for the full plane-stress field in sandwich beams under flexure governed by zigzag warping

Lorenzo Bardella

doi:10.1016/j.compstruct.2023.117754

受之字形翘曲约束的弯曲夹层梁全平面应力场的显式解析解

We provide analytical solutions for the full stress field of straight sandwich beams with identical skins subject to linear elastic flexure governed by zigzag warping, where all layers obey Timoshenko’s kinematics. As a main novelty, we make use of an equilibrium equation for the Cauchy continuum to recover of the through-the-thickness normal stress component, σ y . The new estimates are accurate for a wide range of relative stiffness between skins and core and suitable boundary conditions, as it can be demonstrated through the comparison with detailed finite element simulations where the sandwich is modelled as a two-dimensional continuum. As a main practical result concerned with the study of delamination, we find that at a core–skin interface of a cantilever sandwich subjected to a uniformly distributed load, in a region close to the fully-clamped cross-section, σ y is a tensile stress of magnitude larger than that of the shear stress. On this basis, we infer that the availability of good estimates for σ y , along with those for the longitudinal and shear stresses, may be important for the accurate design of sandwich panels.

我们提供了受人字形翘曲线性弹性弯曲支配的具有相同表皮的直线夹层梁的全应力场分析解,其中所有层均服从季莫申科运动学。作为一项主要创新,我们利用考奇连续体平衡方程恢复了厚度法向应力分量 σ y 。通过与将夹层作为二维连续体建模的详细有限元模拟进行比较,可以证明新的估计值在表皮与夹层之间相对刚度范围较大以及合适的边界条件下都是准确的。作为与分层研究有关的主要实际结果,我们发现在悬臂夹层的夹芯-蒙皮界面上,在靠近完全夹紧横截面的区域,σ y 是一个拉应力,其大小大于剪应力。在此基础上,我们推断σ y 以及纵向应力和剪应力的良好估计值对于夹芯板的精确设计非常重要。


Optimization of fracture toughness in 3D-printed parts: Experiments and numerical simulations

Mohammad Reza Khosravani, Hadi Sadeghian, Majid R. Ayatollahi, Tamara Reinicke

doi:10.1016/j.compstruct.2023.117766

优化 3D 打印部件的断裂韧性:实验和数值模拟

Since additive manufacturing (AM) has been utilized for production of functional end-use parts, the mechanical behavior of the additively manufactured parts is a crucial issue. In the present study, compact tension (CT) test is conducted on 3D-printed polymer parts which are fabricated based on the fused deposition modeling (FDM) technique. Considering the influence of the printing parameters on the mechanical performance of the parts, the specimens are fabricated under different printing parameters. In detail, CT specimens are printed with +45°/−45° and 0°/90° filament directions and 0.2 and 0.5 mm layer thicknesses at printing speed of 20 mm/s and 70 mm/s. Based on the CT tests, the fracture behavior of the parts are investigated and their fracture toughness are determined. In addition, digital image correlation technique is used to determine the strain fields on the surface of the CT specimens. Moreover, a series of finite element analysis is performed to study the mechanical behavior of modeled parts. Additionally, scanning electron microscopic investigation is performed for visual examination of the fractured components. According to the results, optimum printing parameters for maximizing the mechanical properties are determined. Due to the wide applications of the FDM 3D-printed parts, the documented results are beneficial for fabrication of parts with a higher mechanical strength.

由于增材制造(AM)已被用于生产终端功能部件,因此增材制造部件的机械性能是一个至关重要的问题。本研究对基于熔融沉积建模(FDM)技术制造的三维打印聚合物部件进行了紧凑拉伸(CT)测试。考虑到打印参数对零件机械性能的影响,试样是在不同的打印参数下制作的。具体来说,CT 试样是在 +45°/-45° 和 0°/90° 长丝方向、0.2 和 0.5 mm 层厚、20 mm/s 和 70 mm/s 印刷速度下印刷的。根据 CT 测试,研究了部件的断裂行为并确定了其断裂韧性。此外,还利用数字图像相关技术确定了 CT 试样表面的应变场。此外,还进行了一系列有限元分析,以研究建模零件的机械行为。此外,还利用扫描电子显微镜对断裂部件进行了直观检查。根据研究结果,确定了最大化机械性能的最佳印刷参数。鉴于 FDM 3D 打印部件的广泛应用,所记录的结果有利于制造具有更高机械强度的部件。


A novel prefabricated auxetic honeycomb meta-structure based on mortise and tenon principle

Yilin Zhu, Defeng Gao, Yongbo Shao, Hui Chen, Chao Yu, Qingyuan Wang

doi:10.1016/j.compstruct.2023.117782

基于榫卯原理的新型预制辅助蜂窝元结构

Existing auxetic honeycomb meta-structures are generally integrated structures with complicated microstructural geometry which hence should be fabricated by costly additive manufacturing (AM) technology. The high cost and low production efficiency of AM technology is still the main bottleneck restricting the engineering applications of such kind of structures. In this work, a prefabricated auxetic honeycomb meta-structure with modularized components was proposed based on mortise and tenon (M&R) principle originated in ancient China. The modularized components of the prefabricated auxetic honeycomb are all tubular structures which can be easily fabricated by traditional manufacturing with low cost and high technical maturity. The mechanical properties of the proposed meta-structure were then detailed investigated numerically under quasi-static and dynamic loading conditions. The referenced integrated auxetic honeycomb meta-structure was also considered as a benchmark for comparison. Results show that the proposed prefabricated design exhibits lower strength and stiffness compared with its integrated counterpart, owing to the introduction of more flexibility. Consequently, the proposed design processes a much more stable stress plateau stage with a larger deformation range and effectively reduces the reactive force of the protected structure. The present work paves a novel avenue to design protective meta-structures with low-cost and high performance.

现有的助熔蜂窝元结构一般都是具有复杂微观几何结构的集成结构,因此必须采用成本高昂的增材制造(AM)技术来制造。AM 技术的高成本和低生产效率仍然是制约此类结构工程应用的主要瓶颈。本研究基于中国古代的榫卯原理,提出了一种具有模块化组件的预制辅助蜂窝元结构。预制辅助蜂窝的模块化组件均为管状结构,可通过传统制造工艺轻松制造,成本低,技术成熟度高。随后,在准静态和动态加载条件下,对所提出的元结构的力学性能进行了详细的数值研究。同时还将参考的集成辅助蜂窝元结构作为比较基准。结果表明,由于引入了更多的灵活性,拟议的预制设计与集成设计相比,强度和刚度更低。因此,拟议设计的应力平台阶段更为稳定,变形范围更大,并有效降低了受保护结构的反作用力。本研究为设计低成本、高性能的保护性元结构开辟了一条新途径。


Damage behavior of high particle volume fraction composites with initial damage by finite element meso-modeling

Xiaoshan Zhang, Guoqiang Luo, Haohan Zhou, Qinqin Wei, Xiaoyu Yang, Yuxuan Zhu, Peng Cao, Qiang Shen

doi:10.1016/j.compstruct.2023.117785

通过有限元中观建模研究具有初始损伤的高颗粒体积分数复合材料的损伤行为

Analyzing the deformation and damage processes of high particle volume fraction composites (HPVFCs) based on the meso-structure modeling plays an important role in their service lifetime and functional reliability. The reported mesoscopic structural models are usually ideal models without initial damage and apply to composites with the volume fraction of particles less than 80%. This work provides a new mesoscopic structure model called aggregate settlement-merging model to successfully simulate the mechanical behavior and damage mechanism of the polymer-bonded explosive (PBX) under quasi-static loads, and the macroscopic response is accurately predicted by the cohesive finite element method. This simulation commendably predicts the failure modes including interface debonding, binder filaments, and grain failure, which is consistent with the observation in micromechanical experiments. The multi-scale relationship between macroscopic mechanical properties and microscopic initial interface damage is quantitatively established in a form of an exponential function. This study shows a relationship between meso-structures and performance and provides strategy for designing next generation high-performance HPVFCs.

基于中观结构模型分析高颗粒体积分数复合材料(HPVFCs)的变形和损伤过程对其使用寿命和功能可靠性具有重要作用。已报道的中观结构模型通常是无初始损伤的理想模型,适用于颗粒体积分数小于 80% 的复合材料。本研究提供了一种新的介观结构模型--聚合沉降-合并模型,成功模拟了聚合物粘结炸药(PBX)在准静载荷下的力学行为和损伤机理,并通过内聚有限元法准确预测了宏观响应。模拟预测了包括界面脱开、粘结丝和晶粒破坏在内的破坏模式,这与微机械实验的观察结果一致。宏观力学性能与微观初始界面损伤之间的多尺度关系以指数函数的形式定量确定。这项研究表明了介观结构与性能之间的关系,并为设计下一代高性能 HPVFC 提供了策略。


Composites Part B: Engineering

Simulated end-of-life reuse of composites from marine applications using thermal reshaping of seawater-aged, glass fibre-reinforced acrylic materials

Michael Noonan, Winifred Obande, Dipa Ray

doi:10.1016/j.compositesb.2023.111118

 

通过对海水老化的玻璃纤维增强丙烯酸材料进行热重塑,模拟海洋应用中复合材料的报废再利用情况

In this work, end-of-life reuse of continuous fibre-reinforced thermoplastic composites from marine applications has been simulated by thermally reshaping (reprocessing) seawater-aged materials. Specifically, resin-infused, V-shaped glass/acrylic composites were seawater-aged (60 °C; 170 h) and reprocessed in a heated hydraulic press (120 °C; 10 bar). Reprocessing promoted void collapse and increased short beam shear strengths. Unaged reprocessed materials retained 52 % and 57 % performance in flexural strength and modulus, (relative to virgin material), with corresponding retentions of 20 % and 62 % in the aged reprocessed materials, respectively. Ageing- and reprocessing-related flexural performance changes occurred due to mild matrix plasticisation and fibre misalignment, respectively.

在这项工作中,通过对海水老化材料进行热重塑(再加工),模拟了海洋应用中连续纤维增强热塑性复合材料的报废再利用。具体来说,将注入树脂的 V 形玻璃/丙烯酸复合材料进行海水老化(60 °C;170 小时),然后在加热液压机中进行再加工(120 °C;10 巴)。再加工促进了空隙塌陷,提高了短梁剪切强度。未老化的后处理材料在抗弯强度和模量方面分别保持了 52% 和 57% 的性能(相对于原始材料),而老化的后处理材料则分别保持了 20% 和 62% 的性能。与老化和再加工相关的弯曲性能变化分别是由于轻微的基体塑化和纤维错位造成的。


来源:复合材料力学仿真Composites FEM
ACTMechanicalAdditiveDeform断裂复合材料电子增材ADS海洋理论化机材料多尺度
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首次发布时间:2024-11-05
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【新文速递】2023年11月27日复合材料SCI期刊最新文章

今日更新:Composite Structures 3 篇,Composites Part A: Applied Science and Manufacturing 3 篇,Composites Science and Technology 3 篇Composite StructuresExperimental Investigation on Impact Behavior of Curved Sandwich Composites with Chiral Auxetic CoreDilek ATİLLA YOLCU, Buket OKUTAN BABAdoi: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 compositesNan Wang, Weidong Wen, Yipeng Chang, Yu Zhou, Konghan Lu, Hongjian Zhangdoi:10.1016/j.compstruct.2023.1177592.5D 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 algorithmPeng Xiao, Lei Bin, Riccardo Vescovini, Shi Zhengdoi: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%。Composites Part A: Applied Science and ManufacturingClarifying the mechanisms of edge glow generation in CFRP laminates exposed to simulated lightning currentsShintaro Kamiyama, Takao Okada, Yoshiyasu Hirano, Takeo Sonehara, Hiromitsu Miyaki, Toshio Ogasawaradoi: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 studyLi Xiaodong, Yu Zhou, Shintaro Kamiyama, Takao Okada, Tomohiro Yokozekidoi: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 testingWataru Matsunaga, Satoshi Imai, Yoshihiro Mizutani, Tetsuo Yasuoka, Akira Todorokidoi: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。Composites Science and TechnologyHighly conductive and mechanically robust MXene@CF core-shell composites for in-situ damage sensing and electromagnetic interference shieldingYi Hu, Junzhen Chen, Guoyu Yang, Yujun Li, Ming Dong, Han Zhang, Emiliano Bilotti, Jianjun Jiang, Dimitrios G. Papageorgioudoi: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 structureLing Yan, Somia Yassin Hussain Abdalkarim, Xuefei Chen, ZhiMing Chen, Weidong Lu, Jingli Zhu, Meijin Jin, Hou-Yong Yudoi: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 surfacesFenglei Li, Jiakang Gan, Long Zhang, Hailun Tan, Eric Li, Bing Lidoi: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。来源:复合材料力学仿真Composites FEM

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