【新文速递】2024年6月28日复合材料SCI期刊最新文章

今日更新：Composite Structures 4 篇，Composites Part A: Applied Science and Manufacturing 1 篇，Composites Part B: Engineering 5 篇，Composites Science and Technology 2 篇Composite StructuresParametric study on the effect of material properties, tool geometry, and tolerances on preform quality in wind turbine blade manufacturingPeter H. Broberg, Esben Lindgaard, Adam J. Thompson, Jonathan P.-H. Belnoue, Stephen R. Hallett, Brian L.V. Bakdoi:10.1016/j.compstruct.2024.118324关于材料特性、工具几何形状和公差对风力涡轮机叶片制造中预成型质量影响的参数研究Increasing throughput in wind turbine blade production can be achieved by separately manufacturing pre-shaped binder-stabilised dry preforms, and subsequently placing them in the blade mould. To avoid manufacturing defects, a trade-off between the formability and the handleability of the preform is necessary. In this paper, an experimentally validated preform model is used to study how variations in material properties, tool geometry, and placement tolerances influence defect generation. The results from three studies are presented. In the first study, a preform is formed over a ramp transition with variations in geometry. The results from this study indicate that a short ramp promotes transverse shearing of the preform. In the second study, the material properties of the preform are varied. The results indicate that a high mode I cohesive law of the binder and a high bending stiffness of the fabric promote transverse shearing and remove wrinkles. In the last study, placement tolerances for a pre-shaped preform are studied. The results show that if the preform can shear between the preform edge and the tool edge, it can conform to the mould even with large placement offsets. Process engineers and blade designers can readily use these results to help reduce forming-induced wrinkles.要提高风力涡轮机叶片的生产量，可以单独制造预成型的粘合剂稳定干预型件，然后将其放入叶片模具中。为了避免制造缺陷，必须在预型件的成型性和可操作性之间进行权衡。本文使用经过实验验证的预成型模型来研究材料属性、工具几何形状和放置公差的变化如何影响缺陷的产生。本文介绍了三项研究的结果。在第一项研究中，预成型是在几何形状变化的斜坡过渡上形成的。研究结果表明，短斜面会促进预型件的横向剪切。在第二项研究中，预成型件的材料属性发生了变化。结果表明，粘合剂的高模态 I 内聚律和织物的高弯曲刚度可促进横向剪切并消除褶皱。在最后一项研究中，研究了预成型预型件的放置公差。结果表明，如果预型件能在预型件边缘和工具边缘之间发生剪切，那么即使有较大的放置偏差，它也能与模具保持一致。工艺工程师和叶片设计人员可随时利用这些结果来帮助减少成型引起的皱纹。Enhanced prediction of reflected spectrum for FBG Sensors with metallic coating embedded in CFRP composites: unveiling the impact of process-induced residual stress and coating thicknessDong-Hyeop Kim, Sang-Woo Kimdoi:10.1016/j.compstruct.2024.118321增强对 CFRP 复合材料中嵌入金属涂层的 FBG 传感器反射光谱的预测：揭示加工过程引起的残余应力和涂层厚度的影响The occurrence of peak-split or distortion in the reflected light of fiber Bragg grating (FBG) sensors with metallic coatings embedded in composites is inevitable during the curing process, regardless of protection layers. In this study, we present a comprehensive methodology to numerically predict the reflected spectrum of metallic-coated FBG sensors, considering the process-induced residual stress in carbon fiber/epoxy composites. The finite element analysis was utilized to simulate the residual stress, which primarily arises from mechanical, thermal, and chemical cure mechanisms of the composites, including the thermosetting resin. Subsequently, the reflected spectra were calculated using the coupled mode theory. Contrary to common expectations, our findings indicate that the coating thickness has minimal influence on the reflected spectrum, while the residual stress and embedding position significantly impact it. By employing this proposed methodology, the number of experimental trials can be reduced, enabling the development of robust structural and state monitoring systems for composites using metallic-coated FBG sensors.在复合材料中嵌入金属涂层的光纤布拉格光栅 (FBG) 传感器在固化过程中不可避免地会出现峰值分裂或反射光变形，无论是否有保护层。在本研究中，考虑到碳纤维/环氧树脂复合材料在加工过程中产生的残余应力，我们提出了一种全面的方法来对金属涂层 FBG 传感器的反射光谱进行数值预测。残余应力主要来自复合材料（包括热固性树脂）的机械、热和化学固化机制，利用有限元分析来模拟残余应力。随后，利用耦合模式理论计算了反射光谱。与通常的预期相反，我们的研究结果表明，涂层厚度对反射光谱的影响微乎其微，而残余应力和嵌入位置则对其有重大影响。通过采用这种建议的方法，可以减少实验次数，从而利用金属涂层 FBG 传感器开发出稳健的复合材料结构和状态监测系统。On the role of curvature in the response of air-backed composites to hydrodynamic loading: An experimental studyNicco Ulbricht, Nuri Han, Maurizio Porfiridoi:10.1016/j.compstruct.2024.118328关于曲率在气背复合材料对流体动力载荷响应中的作用：实验研究Composite materials are increasingly utilized in high-performance naval structures, due to their superior properties over traditional materials like steel and aluminum. However, their widespread use is hindered by our limited understanding of their behavior when exposed to marine environments. One of the main loading conditions encountered during operations at sea is the hydrodynamic loading on the side in contact with water. Despite the practical significance of curved composite structures, the state-of-the-art on air-backed composites relies on the study of flat plates. Here, we use three-dimensional digital image correlation and planar particle image velocimetry to study the influence of curvature on the dynamic response of composite plates to hydrodynamic loading. Our findings reveal that curvature significantly influences both structural deformations and flow physics. The curved plate experiences localized vibrations with lower amplitude and higher frequency, caused by its increased stiffness. Additionally, the hydrodynamic pressure at the center of the plate decays faster in time for the curved configuration, highlighting the importance of curvature in shaping fluid–structure interactions. Our results advance the understanding of fluid–structure interactions in composite materials and highlight the importance of curvature in the design of resilient marine structures.由于复合材料具有优于钢材和铝材等传统材料的性能，因此越来越多地应用于高性能舰船结构中。然而，由于我们对复合材料在海洋环境中的行为了解有限，因此阻碍了复合材料的广泛应用。海上作业时遇到的主要负载条件之一是与水接触一侧的流体动力负载。尽管曲面复合材料结构具有重要的实际意义，但有关气背复合材料的最新研究主要依赖于对平板的研究。在这里，我们使用三维数字图像相关技术和平面粒子图像测速仪来研究曲率对复合材料板在水动力载荷下的动态响应的影响。我们的研究结果表明，曲率对结构变形和流动物理都有显著影响。由于刚度增加，弧形板会产生振幅更小、频率更高的局部振动。此外，对于曲面结构，板中心的流体动力压力在时间上衰减得更快，这凸显了曲率在形成流体-结构相互作用方面的重要性。我们的研究结果推进了对复合材料中流体与结构相互作用的理解，并强调了曲率在弹性海洋结构设计中的重要性。Deformation mechanics of generalized missing rib chiral lattice structuresAnirvan DasGuptadoi:10.1016/j.compstruct.2024.118333广义缺棱手性晶格结构的变形力学The planar missing rib lattice topology is generalized to construct a family of regular and irregular tetra-chiral periodic lattices. The geometry of a lattice in the family is completely defined by a set of six parameters. Using a unified energy based approach, the constitutive model and all effective elastic properties of the resulting lattice structures are determined from the unit periodic element of the lattice. Straightforward analytical expressions of the effective properties are obtained for some special geometries, which for the general case may be lengthy. In the latter case, the compliance tensor can easily be obtained numerically. The proposed approach involves accurate determination of the strain tensor and the compliance tensor for which a minimum error norm method is used. The results from the analytical expressions are compared with those obtained from Finite Element Analysis (FEA), and a very good match is observed. To draw a parity with experimental determination of the elastic properties and address the observation of auxeticity (negative Poisson’s ratio) in such lattice structures, the concept of empirical Young’s modulus and Poisson’s ratio is introduced. Using this idea, for the conventional chiral lattice, some disagreement in the existing literature is resolved.平面缺棱晶格拓扑学被推广用于构建规则和不规则四手性周期晶格族。该族中网格的几何形状完全由一组六个参数定义。利用基于统一能量的方法，从晶格的单位周期元素确定了由此产生的晶格结构的构成模型和所有有效弹性特性。对于一些特殊的几何结构，可以获得有效特性的直接分析表达式，而对于一般情况，分析表达式可能比较冗长。在后一种情况下，顺应张量可以很容易地通过数值方法获得。所提出的方法涉及应变张量和顺应性张量的精确测定，为此采用了最小误差规范法。将分析表达式得出的结果与有限元分析（FEA）得出的结果进行比较，发现两者非常吻合。为了与弹性特性的实验测定结果保持一致，并解决在此类晶格结构中观察到的辅助eticity（负泊松比）问题，引入了经验杨氏模量和泊松比的概念。对于传统的手性晶格，利用这一概念解决了现有文献中的一些分歧。Composites Part A: Applied Science and ManufacturingMechanically anisotropic stretchable and transparent composite substrates for distortion-free displayHyeongsu Oh, Jung Hur, Soojin Jeong, Seung-hwan Hur, Dong-chun Lee, Yongtaek Hong, Seungjun Chung, Jonghwi Lee, Jeong Gon Sondoi:10.1016/j.compositesa.2024.108338用于无畸变显示器的机械各向异性可拉伸透明复合基板Developing new-form factor devices has led to the creation of foldable and rollable displays. However, next-step stretchable devices with shape changes face a new issue different from conventional displays. When the screen is stretched, screen distortion occurs due to the nature of contraction perpendicular to the stretching direction to preserve the volume. To address this issue, we focused on the composite approach with mechanical anisotropy using continuously aligned fiber fillers. In this study, we fabricated transparent mechanically anisotropic stretchable substrates with near-zero Poisson's ratio by incorporating continuous and aligned transparent ribbon arrays within a transparent, stretchable matrix. The aligned ribbon-reinforced composite substrates have mechanical anisotropy by mainly reinforcing stiffness only in the ribbon-aligned direction. When unidirectional stretchable devices in the direction perpendicular to the alignment are developed, the stiffness of the substrate contracting in the ribbon alignment direction is relatively high compared to the vertical direction, and thus the vertical displacement is diminishing, so substrates with Poisson's ratio close to 0 can be realized. Based on this approach, we realized a light-emitting device (LED) array system with near-zero vertical distortion by attaching LED arrays and printed intrinsically stretchable interconnections on our mechanically anisotropic composite substrate.新型设备的开发催生了可折叠和可卷曲显示器。然而，与传统显示器不同，具有形状变化的下一步可拉伸设备面临着一个新问题。当屏幕被拉伸时，由于垂直于拉伸方向的收缩性质，屏幕会发生变形，以保持体积。为了解决这个问题，我们重点研究了利用连续排列的纤维填充物实现机械各向异性的复合方法。在这项研究中，我们在透明的可拉伸基质中加入了连续排列的透明丝带阵列，从而制造出了机械各向异性的透明可拉伸基质，其泊松比接近零。排列整齐的色带增强复合基板主要在色带排列整齐的方向上增强刚度，从而具有机械各向异性。在开发垂直于排列方向的单向可拉伸设备时，与垂直方向相比，基材在色带排列方向上的收缩刚度相对较高，因此垂直方向上的位移会逐渐减小，从而可以实现泊松比接近 0 的基材。基于这种方法，我们在机械各向异性复合基底上安装了 LED 阵列和印刷的本征可拉伸互连器件，从而实现了垂直变形接近零的发光器件 (LED) 阵列系统。Composites Part B: EngineeringReview on methodologies of fatigue property prediction for carbon fiber reinforced polymerAijia Li, Qianzhu Mao, Jinke Li, Youming Li, Xi Li, Jia Huang, Jun Xing, Chao Zhangdoi:10.1016/j.compositesb.2024.111659碳纤维增强聚合物疲劳性能预测方法综述With the increasing application of CFRP in engineering structures, researchers are devoting more attention to its fatigue issues. Due to the greater complexity and diversity of composite materials compared to metals, the utilization of conventional experimental methods to assess their fatigue performance incurs higher costs. Consequently, enormous efforts have been made to seek accurate and reliable methods for the prediction of fatigue properties of composites in a short time. The present review paper summarizes various fatigue life prediction methods for CFRP composites, including semi-empirical methods, finite element methods, non-destructive testing technology (NDT) based methods and data-driven methods. The advantages, limitations and application scopes of those methods are discussed in details. The semi-empirical methods predict fatigue life expediently and quickly, yet it exhibits limited adaptability to different material types and structural configurations. Finite element methods are applicable for predicting fatigue life in various complex composite engineering structures, but they require extensive experiments for parameter calibration. NDT based methods enable the rapid acquisition of a substantial amount of data relevant to fatigue damage for life prediction; however, accurately correlating NDT data with different types of fatigue damage still needs further investigation. Data-driven methods can integrate extensive historical data for predicting fatigue performance of composite materials; however, effectively filtering and cleansing data related to fatigue remains a challenging task. This review paper aims to provide the most relevant and up-to-date information on the fatigue property prediction methods for CFRP composite, and the potential and development of newly proposed fast prediction methods are also prospected.随着 CFRP 在工程结构中的应用日益广泛，研究人员对其疲劳问题给予了更多关注。与金属材料相比，复合材料具有更高的复杂性和多样性，因此使用传统的实验方法来评估其疲劳性能会产生更高的成本。因此，人们一直在努力寻求准确可靠的方法，以便在短时间内预测复合材料的疲劳性能。本综述总结了 CFRP 复合材料的各种疲劳寿命预测方法，包括半经验方法、有限元方法、基于无损检测技术（NDT）的方法和数据驱动方法。详细讨论了这些方法的优势、局限性和应用范围。半经验方法能快速预测疲劳寿命，但对不同材料类型和结构配置的适应性有限。有限元方法适用于预测各种复杂复合材料工程结构的疲劳寿命，但需要大量实验进行参数校准。基于无损检测的方法可快速获取大量与疲劳损伤相关的数据，用于寿命预测；然而，如何将无损检测数据与不同类型的疲劳损伤准确关联起来，仍需进一步研究。数据驱动方法可以整合大量历史数据，用于预测复合材料的疲劳性能；然而，有效过滤和清理与疲劳相关的数据仍然是一项具有挑战性的任务。本综述旨在提供 CFRP 复合材料疲劳性能预测方法的最新相关信息，并探讨新提出的快速预测方法的潜力和发展。Construction of carbon coated spherical Zn0.71Mn0.29Se@C for high-performance aluminum ion batteriesWei Zhang, Zhibao Wang, Chen Zhang, Yujuan Pang, Wenming Zhang, Zhanyu Lidoi:10.1016/j.compositesb.2024.111661构建用于高性能铝离子电池的碳涂层球形 Zn0.71Mn0.29Se@CAs a high energy density material, selenides have shown highly competitive initial capacity when applied to the positive electrode of aluminum ion batteries. However, in acidic electrolytes, the volume effect of selenides during electrochemical reactions can cause damage to the material structure. In long-term cycling tests, the performance of selenide cathode materials deteriorates rapidly, which greatly limits the application of this high-performance material in aluminum ion batteries. Here, Zn0.71Mn0.29Se@C material was synthesized for the cathode of aluminum ion batteries, which is covered by a carbon layer on the sphere shells and has good crystallinity. Zn0.71Mn0.29Se@C showed excellent performance: the capacity was maintained at 102.79 mAh/g after 2000 cycles. Attributed to the supporting effect of the carbon material, Zn0.71Mn0.29Se@C exhibits excellent structural stability. During charging and discharging, the carbon layer of the sphere shell effectively limits the volume expansion and improves the cycling performance of the battery. Meanwhile, the simulation results show that the Zn0.71Mn0.29Se@C material has a strong trapping effect for AlCl4− ions. As the main ion involved in the reaction, this strong interaction can greatly improve the reaction kinetics. On the other hand, the charge accumulation caused by the embedding of potential ions enhances the charge transfer. In conclusion, the carbon layer in the outer layer of Zn0.71Mn0.29Se@C not only supports the sphere structure, but also enhances the trapping effect for potential ions, and this novel electrode material is expected to improve the application prospect of aluminum ion batteries.作为一种高能量密度材料，硒化物在应用于铝离子电池正极时显示出极具竞争力的初始容量。然而，在酸性电解质中，硒化物在电化学反应过程中的体积效应会对材料结构造成破坏。在长期循环测试中，硒化物正极材料的性能会迅速恶化，这大大限制了这种高性能材料在铝离子电池中的应用。本文合成了用于铝离子电池阴极的 Zn0.71Mn0.29Se@C 材料，该材料在球壳上覆盖有碳层，具有良好的结晶性。Zn0.71Mn0.29Se@C 材料表现出优异的性能：经过 2000 次循环后，其容量保持在 102.79 mAh/g。由于碳材料的支撑作用，Zn0.71Mn0.29Se@C 表现出优异的结构稳定性。在充放电过程中，球壳碳层有效地限制了体积膨胀，提高了电池的循环性能。同时，模拟结果表明，Zn0.71Mn0.29Se@C 材料对 AlCl4- 离子有很强的捕获作用。作为参与反应的主要离子，这种强相互作用能大大改善反应动力学。另一方面，电位离子的嵌入所导致的电荷积聚也增强了电荷转移。总之，Zn0.71Mn0.29Se@C 外层的碳层不仅支持球形结构，还增强了对潜在离子的捕获效果，这种新型电极材料有望改善铝离子电池的应用前景。Preparation of dimensionally stable and strong thin-type bamboo bundle laminated veneer lumber through delignification and phenolic resin synergiesXinpu Li, Hanzhou Ye, Xiang Zhao, Yanjun Li, Ge Wangdoi:10.1016/j.compositesb.2024.111662通过脱木素和酚醛树脂协同作用制备尺寸稳定、强度高的薄型竹束层压单板材The development of thin-type bamboo bundle laminated veneer lumber (T-BLVL) represents a significant advancement in environmentally friendly and sustainable building materials. However, the application of T-BLVL is still hindered by poor dimensional stability and low mechanical strength. In this study, the delignified thin-type bamboo bundle laminated veneer lumber (D-T-BLVL) was prepared through the partial delignification of bamboo bundles and the synergistic effects of phenolic resin (PF). These effects included gluing, strengthening, and waterproofing. D-T-BLVL exhibited high strength, dimensional stability, and a remarkable thickness of only 5 mm. After the removal of 26% lignin, the porosity of bamboo bundles increased by 117% compared with natural bamboo bundles, facilitating enhanced PF infiltration. D-T-BLVL exhibited a bending strength of 281.84 MPa, representing a 83.87% increase over that of T-BLVL (153.38 MPa). Additionally, the water absorption thickness expansion rate of D-T-BLVL (3.37%) was only approximately 1/4 times that of T-BLVL (13.30%). The development of D-T-BLVL provides valuable guidance for developing wind turbines, infrastructures, and other advanced technologies.薄型竹集成材（T-BLVL）的开发标志着环保和可持续建筑材料的重大进步。然而，T-BLVL 的应用仍然受到尺寸稳定性差和机械强度低的阻碍。在这项研究中，通过对竹束进行部分脱木素处理，并在酚醛树脂（PF）的协同作用下，制备出了脱木素薄型竹束层压单板材（D-T-BLVL）。这些作用包括胶合、加固和防水。D-T-BLVL 具有高强度和尺寸稳定性，厚度仅为 5 毫米。在去除 26% 的木质素后，竹束的孔隙率比天然竹束增加了 117%，从而促进了 PF 的渗透。D-T-BLVL 的抗弯强度为 281.84 兆帕，比 T-BLVL 的抗弯强度（153.38 兆帕）提高了 83.87%。此外，D-T-BLVL 的吸水厚度膨胀率（3.37%）仅为 T-BLVL（13.30%）的约 1/4 倍。D-T-BLVL 的开发为开发风力涡轮机、基础设施和其他先进技术提供了宝贵的指导。Compound Nested Lattices with Programmable Isotropy and Elastic Stiffness Up to Theoretical LimitFeng Jiang, Ian P. Seetoh, Hyunwoo Lee, Guo Yao Lim, Dominic Kang Jueh Lim, Jonathan Singham, Chang Qi, Chang Quan Laidoi:10.1016/j.compositesb.2024.111656 具有可编程各向同性和理论极限弹性刚度的复合嵌套晶格A novel class of compound structures, which consists of 2 types of unit cell geometries occupying different sites in the lattice (i.e. compound lattice) was investigated. The arrangement and volume ratio of the 2 unit cell geometries were varied, and it was found that the compound lattices can exhibit up to 4 distinct geometries – 2 from the unit cells and 2 supra-structures from the arrangement of each type of unit cell. In stiffness optimization, the material re-organization tends to emphasize the stiffest of the 4 geometries and collapse the hierarchical compound lattice into a single-level structure. In isotropy optimization, unit cells had to be arranged into supra-structures with an anisotropy profile opposite to that of their geometries. These insights led to the introduction of the compound nested lattices, which exhibited higher specific moduli than previous isotropic designs. The compound nested 1pSC:512pFCC lattice, in particular, reached 97.9% of the Hashin-Shtrikman upper bound at relative density = 0.6, which is the closest approach to the theoretical maximum ever reported.我们研究了一类新型复合结构，它由占据晶格中不同位置的 2 种单胞几何结构（即复合晶格）组成。研究人员改变了 2 种单胞几何结构的排列和体积比，发现复合晶格最多可呈现 4 种不同的几何结构--2 种来自单胞，2 种超结构来自每种单胞的排列。在刚度优化中，材料重组倾向于强调 4 种几何形状中刚度最大的一种，并将分层复合晶格分解为单层结构。在各向同性优化中，必须将单元格排列成超结构，其各向异性轮廓与其几何轮廓相反。这些见解促成了复合嵌套晶格的问世，与之前的各向同性设计相比，复合嵌套晶格具有更高的比模量。特别是复合嵌套 1pSC:512pFCC 晶格，在相对密度 = 0.6 时达到了哈申-施特里克曼上限的 97.9%，这是迄今为止报道的最接近理论最大值的晶格。Enhanced comprehension of the cross-scale forming mechanism in CF/PEEK resistance welding: Analysis of temperature gradients and meso–microscopic phase transitionsYi Zhang, Liangliang Shen, Xinyu Fan, Zhongwei Yan, Juan Xiao, Xigao Jian, Gang Zhao, Jian Xudoi:10.1016/j.compositesb.2024.111660 增强对 CF/PEEK 电阻焊接中跨尺度成形机制的理解：温度梯度和介观相变分析Resistance welding technology is an effective solution for connecting thermoplastic composites. However, limited research on non-uniform distribution of interfacial temperature and complex evolution mechanism of phase-change molding hinders its application. This reliance on traditional experimental and trial-and-error methods severely impedes its development. Therefore, this study employed a novel cross-scale numerical simulation method, being applied for the first time in the field of resistance welding for elucidating the underlying mechanism of joint formation through multi-component phase transformation. The constructed model accurately represented the transient heat transfer of a realistic wire mesh structure in three dimensions, while incorporating complex gradient effects arising from both spatial and temporal variations in heating element temperature due to air interference. Further, melting, flow, and consolidation behavior of the resin matrix in resistance welding of carbon fiber/polyetheretherketone (CF/PEEK) thermoplastic composite was investigated herein at a mesoscopic scale. To accomplish this objective, a three-phase flow spatial forming and evolution model for resistance welding was developed at the mesoscopic scale by integrating principles from fluid dynamics. Interestingly, introduction of an air phase reinstated the spatial voids formation and flow in resistance welding, providing robust evidence for the initiation mechanism of internal defects. Moreover, this study revealed variations in the melting mode of PEEK resin across different regions within the weld and highlighted distinct distributions of voids resulting from uneven heat transfer. The interfacial phenomenon and flow diffusion mechanism between components in resistance welding tests were further verified and discussed through analyzing scanning electron microscopy and energy dispersive spectroscopy results. Temporal and spatial correlation in void distribution within the welding zone was observed, which was found to be consistent with simulation results. Specifically, with the progress of the welding process, air near the wire mesh gradually dispersed into the laminate, with significantly more voids at weld seam edges than in central regions. This research methodology based on stepwise scale reduction offers a promising avenue for investigating resistance welding and other connection forming applications, in particular, within the context of engineering underlying logical behavior.电阻焊接技术是连接热塑性复合材料的有效解决方案。然而，对界面温度非均匀分布和相变成型复杂演化机理的研究有限，阻碍了其应用。对传统实验和试错方法的依赖严重阻碍了其发展。因此，本研究采用了一种新型的跨尺度数值模拟方法，并首次应用于电阻焊接领域，以阐明多组分相变形成接头的内在机理。所构建的模型在三维空间内精确地表现了现实金属丝网结构的瞬态热传导，同时纳入了由于空气干扰导致的加热元件温度空间和时间变化所产生的复杂梯度效应。此外，本文还在中观尺度上研究了碳纤维/聚醚醚酮（CF/PEEK）热塑性复合材料电阻焊接中树脂基体的熔化、流动和固结行为。为了实现这一目标，我们结合流体力学原理，在中观尺度上建立了电阻焊接三相流空间形成和演化模型。有趣的是，空气相的引入恢复了电阻焊接中的空间空隙形成和流动，为内部缺陷的引发机制提供了有力的证据。此外，这项研究还揭示了 PEEK 树脂在焊缝内不同区域的熔化模式变化，并突出显示了因热传导不均而产生的不同空隙分布。通过分析扫描电子显微镜和能量色散光谱分析结果，进一步验证和讨论了电阻焊接试验中部件之间的界面现象和流动扩散机制。通过观察焊接区内空隙分布的时间和空间相关性，发现这与模拟结果一致。具体来说，随着焊接过程的进行，钢丝网附近的空气逐渐分散到层压板中，焊缝边缘的空隙明显多于中心区域。这种基于逐步缩小尺度的研究方法为研究电阻焊接和其他连接成型应用提供了一种前景广阔的途径，特别是在工程基本逻辑行为的背景下。Composites Science and TechnologyElectrical insulation and dielectric properties of aramid fiber reinforced epoxy composites under mechanical stressYifang Wang, Boxue Du, Yun Chen, Xin Lin, Xiaoxiao Kongdoi:10.1016/j.compscitech.2024.110733 芳纶纤维增强环氧树脂复合材料在机械应力下的电绝缘和介电特性In this work, an in-situ testing platform that could simultaneously apply high voltage (HV) and mechanical stress has been established. The dielectric properties evolution of aramid fiber reinforced composite (AFRC) under different tensile stresses is investigated systematically. The results show that there is a significant influence on the electrical insulation performance of AFRC, when the applied tensile stress reaches 45% of the ultimate tensile stress (UTS). Elevated tensile stress will induce interface strain concentration inside composites under this condition, which is prone to cause local damage and defects, consequently enhancing charge accumulation under HV. As the tensile stress continues to increase, it is observed that the absorbed charge around defects increases by 49.4% under 60% UTS, accompanied by a discernible decline in the partial discharge inception voltage (PDIV) by 46.9%. With the increase of absorbed charge, the localized intense electric field is formed, thereby fostering partial discharge and breakdown failure. Therefore, it is important to pay more attention to the evolution of dielectric properties of AFRC under mechanical stress in the design and assessment of aramid-based insulation rods. © 2014 xxxxxxxx. Hosting by Elsevier B.V. All rights reserved.在这项工作中，建立了一个可同时施加高压（HV）和机械应力的原位测试平台。系统研究了芳纶纤维增强复合材料（AFRC）在不同拉伸应力下的介电性能演变。结果表明，当施加的拉伸应力达到极限拉伸应力（UTS）的 45% 时，芳纶纤维增强复合材料的电绝缘性能会受到显著影响。在此条件下，拉伸应力升高会引起复合材料内部的界面应变集中，容易造成局部损伤和缺陷，从而加剧高压下的电荷积累。随着拉伸应力的不断增加，可以观察到在 60% UTS 条件下，缺陷周围吸收的电荷增加了 49.4%，同时局部放电起始电压（PDIV）明显下降了 46.9%。随着吸收电荷的增加，会形成局部强电场，从而促进局部放电和击穿失效。因此，在设计和评估芳纶基绝缘棒时，必须更加关注 AFRC 在机械应力作用下的介电性能演变。© 2014 xxxxxxxx.由 Elsevier B.V. 托管。保留所有权利。Asymmetric multilayered cellulose nanofiber composite membranes with electrical-magnetic dual-gradient architectures towards excellent electromagnetic interference shielding performanceYing Zhou, Bai Xue, Lingjun Zeng, Lan Xie, Qiang Zhengdoi:10.1016/j.compscitech.2024.110729 具有电磁双梯度结构的非对称多层纤维素纳米纤维复合膜，实现卓越的电磁干扰屏蔽性能The structural design strategies of MXene-based nanocomposites have demonstrated critical significance for electromagnetic interference (EMI) shielding applications. Herein, novel asymmetric multilayered cellulose nanofiber/multiwalled carbon nanotube@ferroferric oxide/MXene (CNF/MWCNT@Fe3O4/MXene) composite membranes with electrical-magnetic dual-gradient structures were prepared via layered-by-layered self-assembly strategy. Briefly, CNF/MWCNT@Fe3O4 layers are designed as the negative gradient absorption layers which provide dielectric/magnetic double loss. Meanwhile, MXene layers serve as the positive gradient reflection layers which generate multiple reflections and conduct loss. Thus, gradient multilayered CNF/MWCNT@Fe3O4/MXene composite membranes exhibit a total electromagnetic interference shielding effectiveness (EMI SET) of 73.20 dB at the thickness of 180 μm and R-value of 0.99934 in the X-band. Furthermore, the asymmetric gradient multilayer composite membrane reveals a superior EMI shielding performance in comparison with that of homogeneous multilayered composite membranes. When electromagnetic waves (EMWs) pass through the gradient multilayered CNF/MWCNT@Fe3O4/MXene composite membrane, the rational asymmetric gradient multilayered structures contribute to a “gradually decreasing absorption-gradually increasing reflection” shielding mechanism. Thereby, the design strategy of asymmetric electrical-magnetic dual-gradient structures is advantageous in enhancing the EMI shielding ability of polymeric composites.基于氧化亚铁的纳米复合材料的结构设计策略对于电磁干扰（EMI）屏蔽应用具有重要意义。本文通过逐层自组装策略制备了具有电磁双梯度结构的新型非对称多层纤维素纳米纤维/多壁碳纳米管@氧化铁/MXene（CNF/MWCNT@Fe3O4/MXene）复合膜。简而言之，CNF/MWCNT@Fe3O4 层被设计为负梯度吸收层，可提供介电/磁双损耗。同时，MXene 层作为正梯度反射层，可产生多重反射和传导损耗。因此，梯度多层 CNF/MWCNT@Fe3O4/MXene 复合膜在厚度为 180 μm 时的总电磁干扰屏蔽效能（EMI SET）为 73.20 dB，在 X 波段的 R 值为 0.99934。此外，与同质多层复合膜相比，非对称梯度多层复合膜的电磁干扰屏蔽性能更优越。当电磁波（EMWs）穿过梯度多层 CNF/MWCNT@Fe3O4/MXene 复合膜时，合理的非对称梯度多层结构有助于形成 "吸收逐渐减弱-反射逐渐增强 "的屏蔽机制。因此，非对称电磁双梯度结构的设计策略有利于增强聚合物复合材料的电磁干扰屏蔽能力。来源：复合材料力学仿真Composites FEM