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【新文速递】2024年8月28日复合材料SCI期刊最新文章

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今日更新:Composite Structures 4 篇,Composites Part A: Applied Science and Manufacturing 1 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 1 篇

Composite Structures

Numerical assessment of fiber distribution effects on strain-hardening cement composites using a rate-dependent Voronoi-Cell-Lattice-Model

Ji Woon Park, Bonhwi Choo, Jeongun Lee, Yun Mook Lim

doi:10.1016/j.compstruct.2024.118515

基于速率相关Voronoi-Cell-Lattice-Model的纤维分布对应变硬化水泥复合材料影响的数值评估

Strain-hardening cementitious composites, also known as high-performance fiber-reinforced cementitious composites, display exceptional strength and toughness not only under static conditions but also under high-speed dynamic loading. The mechanical properties of these composites are greatly influenced by the orientation and dispersion of embedded fibers. However, experimental analysis of complex fiber arrangements in real specimens has limitations, necessitating the development of computational models to understand the impact of fiber distribution. This study examines the effect of fiber distribution conditions on composite behavior using a Voronoi-Cell-Lattice-Model that incorporates reinforcing effects into discrete-type quasi-brittle matrix elements. Firstly, virtual fiber distribution models revealed that as the gauge length of specimens increased, weaknesses in fiber distribution were more likely to form, leading to decreased strength and strain capacity. Secondly, the model demonstrated that favorable fiber orientation relative to the loading direction and minimal sectional deviation in fiber dispersion significantly increased strain capacity and toughness. Finally, the study explored the wall-effect that may arise during specimen fabrication due to the boundary of the casting mold.

应变硬化胶凝复合材料,也被称为高性能纤维增强胶凝复合材料,不仅在静态条件下,而且在高速动态载荷下都表现出优异的强度和韧性。包埋纤维的取向和分散对复合材料的力学性能有很大影响。然而,对真实样品中复杂纤维排列的实验分析存在局限性,需要开发计算模型来了解纤维分布的影响。本研究使用Voronoi-Cell-Lattice-Model来检验纤维分布条件对复合材料性能的影响,该模型将增强效应纳入离散型准脆性基体元素中。首先,虚拟纤维分布模型表明,随着试件规范长度的增加,纤维分布的弱点更容易形成,从而导致强度和应变能力下降。其次,该模型表明,相对于加载方向有利的纤维取向和纤维分散的最小截面偏差显著提高了应变能力和韧性。最后,研究探讨了由于铸型边界在试样制作过程中可能产生的壁效应。


Transient thermal fracture analysis of a honeycomb layer with a central crack

Wenzhi Yang, Zengtao Chen

doi:10.1016/j.compstruct.2024.118518

含中心裂纹蜂窝层的瞬态热断裂分析

Auxetic honeycomb materials with negative Poisson’s ratio received rapidly growing attention in recent years owing to their exceptional thermomechanical properties in constructing sandwich composites. The objective of this article is to investigate the transient thermal behavior and fracture risk of a honeycomb layer with a central crack subject to a sudden thermal shock by theoretical modeling. Two different material configurations along both orthogonal directions, as well as the conventional and auxetic hexagonal alumina honeycomb cells, are examined to illustrate their effects on the thermal stress intensity factors. To solve the thermoelastic governing equations subject to complex boundary conditions, the methodology of integral transform with singular integral equation is employed. The numerical results demonstrate that the auxetic honeycombs can reduce the thermal stress intensity factors significantly compared to their conventional counterparts. The ratio of stress intensity factors in auxetic to non-auxetic honeycombs under the same absolute value of the internal cell angle θ decreases monotonically with increasing |θ|. In addition, the effects of the relative density, crack length, and crack position are investigated. Our findings would provide a more comprehensive understanding of the honeycomb’s fracture behaviors and contribute to the material design of the sandwich composites with honeycomb cores.

负泊松比辅助蜂窝材料由于其在构建夹层复合材料中具有优异的热力学性能,近年来受到越来越多的关注。本文的目的是通过理论建模研究中心裂纹蜂窝层在突然热冲击作用下的瞬态热行为和断裂风险。研究了正交方向上两种不同的材料结构,以及常规和非对称六方氧化铝蜂窝电池,以说明它们对热应力强度因子的影响。为求解复杂边界条件下的热弹性控制方程,采用奇异积分方程的积分变换方法。数值结果表明,与传统蜂窝相比,辅助蜂窝能显著降低热应力强度因子。在相同胞内角θ绝对值下,随|θ|的增大,消声与非消声蜂窝的应力强度因子之比单调减小。此外,还研究了相对密度、裂纹长度和裂纹位置的影响。本研究结果将为蜂窝的断裂行为提供更全面的认识,并有助于蜂窝芯夹层复合材料的材料设计。


Multiscale fatigue life prediction model for CFRP laminates considering the mechanical degradation of its constituents and the local stress concentration of the matrix

Jeong Hwan Kim, Dongwon Ha, Hoil Choi, Gun Jin Yun

doi:10.1016/j.compstruct.2024.118519

考虑构件力学退化和基体局部应力集中的CFRP复合材料多尺度疲劳寿命预测模型

In the present research, a novel approach for predicting the fatigue life of composites is proposed using a multiscale fatigue model. This model considers two critical physical phenomena that occur in CFRP laminates under tension-tension cyclic loading – the degradation of the physical properties of CFRP constituents and the localized stress concentrations within the matrix. To achieve this, Mori-Tanaka’s mean field theory, a well-known micromechanics model, is employed to consider the deterioration of material properties in various phases, which is dependent on the applied stress level. Localized stress concentration phenomena within the matrix of a composite material are common when CFRP laminate is subjected to cyclic loading. The localized stress concentration on a matrix with different numbers of fibers and orientations using representative volume elements (RVE) is investigated. Two other scales of failure criteria are defined to evaluate its constituent at the material level and ply level at the macroscale. A comparison with fatigue experiment data of AS4/3501-6 composite shows good reliability of the proposed multiscale fatigue model.

本研究提出了一种利用多尺度疲劳模型预测复合材料疲劳寿命的新方法。该模型考虑了CFRP层压板在拉伸-拉伸循环载荷下发生的两个关键物理现象——CFRP成分物理性能的退化和基体内的局部应力集中。为了实现这一点,Mori-Tanaka的平均场理论,一个著名的微观力学模型,被用来考虑材料性能在不同阶段的恶化,这取决于施加的应力水平。复合材料复合材料在循环荷载作用下,基体内部存在局部应力集中现象。利用代表性体积元(RVE)研究了不同纤维数和取向的基体上的局部应力集中。定义了另外两个尺度的破坏准则,分别在材料水平和层数水平上对其成分进行评价。与AS4/3501-6复合材料的疲劳试验数据对比表明,所提出的多尺度疲劳模型具有良好的可靠性。


Modified mode I fracture toughness calculation method for composite laminate with large scale fiber bridging

Qingfeng Duan, Haixiao Hu, Dongfeng Cao, Wei Cai, Junkang Xia, Shuxin Li

doi:10.1016/j.compstruct.2024.118521

大型纤维桥接复合材料层合板的修正I型断裂韧性计算方法

Experimental investigation and theoretical analysis have been carried out in this study to assess the application limitation of the current ASTM D5528 method for Mode I fracture toughness calculation of composite laminate with fiber bridging. It is revealed that additional toughening effect introduced by the fiber bridging is not fully considered in the current method and consequently there are uncertainties associated with the fracture toughness calculated by the current ASTM method. Based on the same principle used in the development of the original ASTM method, a modified method is proposed to extend the applicability of the current method. The modified method is verified with mechanisms based cohesive zone modelling and numerical simulations of the Mode I delamination double cantilever beam tests. The significant improvement of the prediction results compared with experimental results by the modified method over the current method demonstrated its applicability for Mode I delamination fracture toughness calculation of composite laminates with large scale fiber bridging.

本研究通过实验研究和理论分析来评估现行ASTM D5528方法在纤维桥接复合材料层合板I型断裂韧性计算中的应用局限性。结果表明,目前的方法没有充分考虑纤维桥接带来的额外增韧效应,因此现行ASTM方法计算的断裂韧性存在不确定性。在与原ASTM方法发展的原理相同的基础上,提出了一种改进的方法,以扩大现有方法的适用性。通过基于力学的内聚区建模和I型脱层双悬臂梁试验的数值模拟,验证了改进方法的有效性。修正后的方法预测结果与实验结果相比有明显改善,表明该方法适用于大规模纤维桥接复合材料层合板的I型分层断裂韧性计算。


Composites Part A: Applied Science and Manufacturing

Enhancing interfacial performance and fracture toughness of carbon fibre reinforced thermoplastic composites

Yao Chen, Vishnu Prasad, Miray Yasar, Neal Murphy, Alojz Ivankovic

doi:10.1016/j.compositesa.2024.108434

 

提高碳纤维增强热塑性复合材料的界面性能和断裂韧性

Enhancing the interlaminar fracture toughness of composites significantly improves their load bearing capacity and structural integrity over longer service life by improving their resistance to delamination. The effect of hybrid toughening of Elium-based thermoplastic composites involving polydopamine (PDA), multi-walled carbon nanotubes (MWCNTs) sizing, and polyphenylene sulfide (PPS) veil interlayers was investigated to observe the mechanical response using 3-point bending, interlaminar shear strength, and Mode I fracture toughness tests. The enhancement of fibre–matrix adhesion contributed to improvements in both flexural strength and interlaminar shear strength, while additional toughening mechanisms, such as PDA bridging, PPS pull-out and breakage, and fibre bridging, enhanced the Mode I interlaminar fracture toughness by 218%.

提高复合材料的层间断裂韧性,通过提高复合材料的抗分层能力,显著提高复合材料的承载能力和结构完整性,延长复合材料的使用寿命。通过3点弯曲、层间剪切强度和I型断裂韧性测试,研究了聚多巴胺(PDA)、多壁碳纳米管(MWCNTs)和聚苯硫醚(PPS)复合材料杂化增韧的效果。纤维基质粘附性的增强有助于提高弯曲强度和层间剪切强度,而额外的增韧机制,如PDA桥接、PPS拔出和断裂以及纤维桥接,使I型层间断裂韧性提高了218%。


Composites Part B: Engineering

Stretch-Steering of Highly Aligned Discontinuous Fiber Tape with Automated Fiber Placement

Alexander Legenstein, Lukas Fussel, Dirk Heider, John W. Gillespie, Thomas A. Cender

doi:10.1016/j.compositesb.2024.111801

 

高度对准不连续纤维带自动铺布的拉伸控制

Highly aligned discontinuous fiber (ADF) composites have been developed with mechanical properties comparable to continuous fiber composites. These materials can be stretched in the fiber direction during processing enabling the production of complex geometries. This study utilizes 57% fiber volume fraction ADF tape comprised of a thermoplastic Polyetherimide (PEI) matrix with 3 mm long IM7 carbon fibers. The Laser-Assisted Automated Fiber Placement (LA-AFP) process is used to study the limits of stretch-steering of ADF tape at small radii. An experimental technique based on photogrammetry was developed to quantify the effect of stretch parameters on the tape strain fields and path placement accuracy. The measurements captured the local in-plane strain tensor (longitudinal, transverse, and shear) across the width and along the length of steered tapes. The results demonstrate that placement path accuracy can be achieved when the tool center point (center of rotation) of the AFP head is located at the nip-point versus the roller centerline, which is typically used for steering continuous fiber tapes at large steering radii. Accuracy of the in-situ tape stretching was demonstrated up to 60% applied stretch strain. The measurements also confirm that when stretch-steering ADF tape, the resulting strain across the tape width is on average the superposition of the in-situ applied tensile strain and in-plane bending computed from the tape width and steering radius. A statistical-based methodology is presented to select the average tensile stretch levels to minimize the probability of defects forming during steering on the inner radius of the tape. The experiments show that a 12.5 mm wide tape can be accurately placed on a 50 mm radius of curvature without defects. This represents a two order of magnitude improvement in steerability over continuous fiber tapes of the same tape width found in peer-reviewed literature.

高度排列的不连续纤维(ADF)复合材料具有与连续纤维复合材料相当的力学性能。这些材料可以在加工过程中向纤维方向拉伸,从而生产出复杂的几何形状。本研究使用由热塑性聚醚酰亚胺(PEI)基体和3mm长的IM7碳纤维组成的纤维体积分数为57%的ADF胶带。采用激光辅助自动铺放光纤(LA-AFP)工艺研究了ADF胶带在小半径处的拉伸转向极限。提出了一种基于摄影测量的实验技术,以量化拉伸参数对胶带应变场和路径放置精度的影响。测量捕获了局部平面内应变张量(纵向、横向和剪切),沿着导向胶带的宽度和长度。结果表明,当AFP头的工具中心点(旋转中心)位于夹尖点而不是滚轮中心线时,可以实现放置路径精度,这通常用于在大转向半径下转向连续纤维带。原位胶带拉伸的精度可达60%的拉伸应变。测量结果还证实,当拉伸导向ADF胶带时,在胶带宽度上产生的应变是现场施加的拉伸应变与根据胶带宽度和导向半径计算的平面内弯曲的平均叠加。提出了一种基于统计的方法来选择平均拉伸水平,以尽量减少在胶带内半径上转向过程中形成缺陷的概率。实验表明,12.5 mm宽的胶带可以精确地放置在半径为50 mm的曲率上而没有缺陷。与同行评议文献中发现的相同磁带宽度的连续光纤磁带相比,这代表了两个数量级的可操作性改进。


Composites Science and Technology

Unlocking thermal management capacity: Optimized organic-inorganic hybrid shell phase change microcapsules with controllable structure and enhanced conductivity

Xueting Wang, Huaxin Chen, Dongliang Kuang, Xiao Huan, Zhengyuan Zeng, Cong Qi, Shanjian Han, Guanyu Li

doi:10.1016/j.compscitech.2024.110836

 

解锁热管理能力:优化结构可控、电导率增强的有机-无机杂化壳相变微胶囊

Microencapsulated phase change material (MPCM) stands as a strong candidate for temperature control of thermal management systems in broad fields like building construction. A novel design strategy for hybridized shell-based MPCM (HMPCM) containing methyl methacrylate (MMA) and silica was developed by the interfacial hydrolysis-condensation method, with characteristics of controllable structure and enhancement in the interaction between the polymer and inorganic thermal conductivity additives. Two hybridized shell structures, including a homogeneous structure and another unique porous cavity structure shaped like a foam, can be obtained by adjusting for preparation conditions. The results reveal that the thermal conductivity is significantly enhanced by hybridized shells compared to pure MMA shells, with a dramatic increment of 92.16%. Therefore, a highly satisfactory microcapsule material characterized by superior thermal conductivity and energy storage efficiency exceeding 99.9% was fabricated. The results of thermal cycling reliability assessments underscore the favorable attributes of microcapsules, encompassing stable charging/discharging behavior, exceptional phase change reversibility, and prompt thermal responsiveness. Moreover, the feasibility of microcapsules in building thermal management applications has been verified. The temperature difference of 10.3 °C between the matrix with and without microcapsules demonstrates the capability of HMPCMs to effectively regulate the temperature of the surrounding environment. Consequently, these newly developed HMPCMs reinforced by hybridized shells are promising thermoregulation materials for thermal management systems that await further applications.

微封装相变材料(MPCM)是建筑施工等广泛领域热管理系统温度控制的有力候选材料。采用界面水解-缩合的方法,提出了一种新型的含甲基丙烯酸甲酯(MMA)和二氧化硅的杂化壳基MPCM (HMPCM)的设计策略,该策略具有结构可控和增强聚合物与无机导热添加剂相互作用的特点。通过调整制备条件可得到两种杂化壳结构,包括均匀结构和另一种独特的泡沫状多孔腔结构。结果表明,与纯MMA壳层相比,杂化壳层的导热系数显著提高,增幅达92.16%。因此,制备了一种导热性能优异、储能效率超过99.9%的令人满意的微胶囊材料。热循环可靠性评估的结果强调了微胶囊的优点,包括稳定的充放电行为、异常的相变可逆性和快速的热响应性。此外,还验证了微胶囊在建筑热管理应用中的可行性。带微胶囊和不带微胶囊的基质温差为10.3℃,表明hmpcm能够有效调节周围环境温度。因此,这些新开发的杂化壳增强的hmpcm是热管理系统中有前途的热调节材料,有待进一步应用。



来源:复合材料力学仿真Composites FEM
ACTMechanicalAdditiveSystem疲劳断裂复合材料建筑UG裂纹理论材料储能多尺度控制试验
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【新文速递】2024年7月18日复合材料SCI期刊最新文章

今日更新:Composite Structures 5 篇,Composites Part A: Applied Science and Manufacturing 1 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 2 篇Composite StructuresTopological optimization design of multi-material phononic crystals with floating projection constraints to achieve ultra-wide band gapLin Liao, Song Yao, Yingli Lidoi:10.1016/j.compstruct.2024.118387基于浮动投影约束的多材料声子晶体拓扑优化设计,实现超宽带隙The multi-material phononic crystals (PnCs) not only has the potential to achieve broadband vibration reduction and noise control, but also has the capability to reduce costs and weight. This paper proposes a single variable based topological optimization method for widening the band gaps (BGs) in multi-material PnCs. The method combines the floating projection topology optimization (FPTO) method, and utilizes an adjustable stair form interpolation model is used to construct a mapping from a single design variable field to a multi-material field. It avoids the nested form of overlap between different materials to characterize multiple material phases, and the parameter self adaptability of FPTO solves the problem of multiple parameters in univariate optimization methods. Floating projection constraint is used to improve the projection strategy for intermediate densities to obtain a 0/1 design, resulting in a final design with a clear topological structure. Optimized PnCs using various engineered materials are generated to improve BG performance which can rival Au/Epoxy systems. And the effects of mass and cost constraints is also considered to achieve multi-material PnCs by maximizing the BG. The results also indicate that the resulting multi-material PnCs may achieve ultra-wide BG characteristics.多材料声子晶体(pnc)不仅具有实现宽带减振和噪声控制的潜力,而且具有降低成本和重量的能力。提出了一种基于单变量的多材料pnc带隙增宽拓扑优化方法。该方法结合浮动投影拓扑优化(FPTO)方法,利用可调阶梯形式插值模型构建从单一设计变量场到多材料场的映射。它避免了不同材料之间重叠的嵌套形式来表征多个材料相,FPTO的参数自适应性解决了单变量优化方法中的多参数问题。利用浮动投影约束对中间密度的投影策略进行改进,得到0/1的设计,最终得到拓扑结构清晰的设计。使用各种工程材料生成的优化pnc可以提高BG性能,可以与Au/环氧树脂系统相媲美。同时考虑了质量和成本限制的影响,通过最大化BG来实现多材料pnc。结果还表明,所得到的多材料pnc可以实现超宽BG特性。Experimental tensile testing of the lap joint composite laminates supported with the acoustic emission and machine learning techniquesRayane El Mohtadi, Jakub Rzeczkowski, Izabela Korzec-Strzałka, Sylwester Samborski, Francesco Aymerich, Aleksander Czajkadoi:10.1016/j.compstruct.2024.118394基于声发射和机器学习技术的搭接复合材料层合板拉伸试验研究This paper investigates tensile behavior of through thickness reinforced carbon/epoxy lap joint composite laminates, reinforced with steel z-pins and staples, arranged in two rows parallel to the overlapping edges, via experimental testing. Acoustic emission (AE) monitoring is employed during the displacement-controlled tensile tests to monitor damage propagation during loading using the Vallen AMSY-5 measurement system, with two piezoelectric sensors being mounted at the laminate surface. Furthermore, machine learning algorithms are integrated to process AE data, enabling the recognition and prediction of failure mechanisms. Fractographic analyses were performed to observe the nature of damage post-failure. The experimental research was enriched with capturing high-resolution pictures of total crack propagation length growth using a high-resolution photocamera. The performed empirical tests demonstrated that the unstable propagation of a crack along the bonding interface has led to an eventual breakdown of both unreinforced and reinforced joints. An increase in the full displacement and load at failure was clearly detected for both z-pins and staples with a noticeable decrease in crack growth length, while a higher performance was illustrated for staples in comparison to z-pinned and unpinned.通过实验测试,研究了通过厚度增强的碳/环氧搭接复合材料层合板的拉伸性能。在位移控制拉伸试验过程中,使用valallen公司的AMSY-5测量系统进行声发射(AE)监测,以监测加载过程中的损伤传播,两个压电传感器安装在层压板表面。此外,还集成了机器学习算法来处理声发射数据,从而能够识别和预测故障机制。进行断口分析以观察破坏后的损伤性质。利用高分辨率相机拍摄裂纹扩展总长度增长的高分辨率图像,丰富了实验研究。经验试验表明,裂纹沿粘结界面的不稳定扩展会导致未加筋和加筋节点的最终破坏。破坏时的全位移和载荷明显增加,裂纹扩展长度明显减少,而与z钉钉和未钉钉相比,钉钉具有更高的性能。A reliable methodology for the preliminary design of multidirectional composite Open-Hole plates using the coupled criterionT.V. Birro, R. Hamze, A. Maziz, A. Abin, B. Gelydoi:10.1016/j.compstruct.2024.118400用耦合准则对多向复合开孔板进行初步设计的可靠方法In the aerospace industry, composite structures are preferred for their high strength-to-mass ratio and fatigue strength. However, using advanced non-linear Finite Element models for the strength prediction of composite laminates during preliminary design and optimisation can lead to long computing times. Thus, linear elastic fracture mechanics is suitable for preliminary design. In this work, the coupled energy–stress criterion has been successfully applied to predict translaminar failure of open-hole tensile and compression specimens, considering three different stacking sequences with varying degrees of orthotropy. This criterion uses stress and energy criteria as necessary conditions for fracture. Neither of them is sufficient alone. The approach involves a characteristic length dependent on the composite’s properties and geometry. The characteristic length is used to satisfy both criteria simultaneously, avoiding the need for correction factors. The current approach includes the material anisotropy in both elastic and fracture parameters. The onsets of symmetric and antisymmetric crack patterns are investigated, considering where failure is predicted from the ply properties.在航空航天工业中,复合材料结构因其高强度质量比和高疲劳强度而受到青睐。然而,在复合材料层合板的初步设计和优化过程中,使用先进的非线性有限元模型进行强度预测可能会导致较长的计算时间。因此,线弹性断裂力学适用于初步设计。考虑三种不同正交异性的不同堆叠顺序,将能量-应力耦合准则成功地应用于裸眼拉伸和压缩试件的层间破坏预测。该准则使用应力和能量准则作为断裂的必要条件。它们单独都不充分。该方法涉及依赖于复合材料的属性和几何形状的特征长度。特征长度用于同时满足两个标准,避免了对校正因子的需要。目前的方法包括材料在弹性和断裂参数上的各向异性。考虑到从厚度特性预测破坏的位置,研究了对称和反对称裂纹模式的开始。Multifunctional design of an X-lattice interlocked sandwich structure with integrated electromagnetic wave regulation, convective heat transfer and load bearing performancesMinghui Cao, Hongbin Yan, Pengfei Xiao, Chunping Zhou, Linghao Cheng, Yiwei Han, Yifei Chen, Leilei Yan, Xitao Zhengdoi:10.1016/j.compstruct.2024.118401集电磁波调节、对流换热和承载功能于一体的x晶格互锁夹层结构的多功能设计Based on the concept of periodic structural unit, combined with interlocking technology, a novel X-lattice interlocked sandwich structure (XISS) was proposed in this paper for achieving electromagnetic (EM) wave regulation, heat dissipation and load bearing. Spoof surface plasmon polaritons (SSPPs) structures realized by gradient copper wire arrays were integrated with glass fiber reinforced plastic (GFRP) diaphragm walls, and then interlocked into GFRP X-lattices to form the XISS. EM simulated and experimental results demonstrated that the SSPPs structures could effectively improve the transmission performance, and the average transmissivity was increased by 22 % at frequency range from 6.93 GHz to 13.95 GHz. Moreover, heat transfer simulated results revealed that the X-lattices effectively induced vortex formation, leading to a higher convective heat transfer efficiency and improving the overall Nusselt number by 204.24 % compared to traditional rectangular honeycombs under the same Reynolds number Besides the advantages above, the good compressive performance of the XISS exhibited the great potential of structural–functional integration designs, offering the broad prospects in practical engineering application.基于周期结构单元的概念,结合联锁技术,提出了一种新型的x晶格联锁夹层结构(XISS),以实现电磁波调节、散热和承载。利用梯度铜线阵列实现的欺骗表面等离子激元(SSPPs)结构与玻璃纤维增强塑料(GFRP)隔膜壁集成,然后互锁在GFRP x晶格中形成XISS。电磁仿真和实验结果表明,SSPPs结构可以有效地提高传输性能,在6.93 GHz ~ 13.95 GHz频率范围内,平均透射率提高了22 %。此外,传热模拟结果表明,在相同雷诺数下,x -晶格有效地诱导了涡流的形成,从而提高了对流换热效率,使整体努塞尔数比传统矩形蜂窝提高了204.24 %。除此之外,XISS良好的抗压性能显示了结构功能一体化设计的巨大潜力。具有广阔的工程应用前景。A novel Star-4 honeycomb with the inclined ligaments for enhanced tunability of wave propagation behaviorsHengtai Ni, Jing Liu, Liming Guo, Tan Zeng, Guang Pandoi:10.1016/j.compstruct.2024.118405一种新型的具有倾斜韧带的Star-4蜂窝,增强了波传播行为的可调性The dynamic mechanical properties of mechanical metamaterials based on the honeycomb structures are widely concerned, especially the wave propagation behaviors. In this study, a novel type of honeycomb is designed by combing the Star-4 structure with the inclined ligaments. A dynamic analysis model of the Star-4 honeycomb with the inclined ligaments (S4HILs) is established based on the periodic description by the Bloch’s theorem and the discretization by the finite element theory of Timoshenko beam. The band gap characteristics calculated by the proposed model are compared with the frequency responses obtained by the commercial software to provide the modeling validation. The boundary vibration modes of S4HILs are compared to reveal the formation and closure mechanism of band gap. Moreover, the effects of different types of geometrical features on the band gap distribution and the macro-Poisson’s ratio are systematically investigated. The group velocity is finally discussed according to the global dispersion relation to explore the directivity of wave propagation. The results indicate that the inclined ligament can significantly enhance the tunability of wave propagation behaviors, which is mainly reflected in the broadened regulation range of band structure, Poisson’s ratio, and group velocity. This work provides an innovative idea for the regulation of wave propagation behaviors though the connection design between mechanical metamaterial unit cells.基于蜂窝结构的力学超材料的动态力学性能,特别是波的传播特性受到了广泛的关注。本研究将Star-4结构与倾斜韧带相结合,设计了一种新型的蜂窝结构。基于Bloch定理的周期描述和Timoshenko梁有限元理论的离散化,建立了具有倾斜韧带的Star-4蜂窝(S4HILs)动力分析模型。将该模型计算的带隙特性与商用软件获得的频率响应进行了比较,以验证模型的有效性。比较了S4HILs的边界振动模式,揭示了带隙的形成和闭合机理。此外,系统地研究了不同类型几何特征对带隙分布和宏观泊松比的影响。最后根据整体频散关系讨论了群速度,探讨了波传播的方向性。结果表明,斜韧带能显著增强波传播行为的可调性,主要表现在能带结构、泊松比和群速的调节范围扩大。本工作为通过机械超材料单元胞之间的连接设计来调节波的传播行为提供了一种创新思路。Composites Part A: Applied Science and ManufacturingCyclic behaviour of 3D-woven composites in tension: Experimental testing and macroscale modellingCarolyn Oddy, Meng yi Song, Christian Stewart, Bassam El Said, Magnus Ekh, Stephen R. Hallett, Martin Fagerströmdoi:10.1016/j.compositesa.2024.108354三维编织复合材料在张力中的循环行为:实验测试和宏观模型Composites with 3D-textile reinforcement present several engineering advantages. However, their intricate yarn architecture also creates a material with a number of nonlinear behaviours and features, which need to be understood in order to enable their efficient use. To demonstrate the anisotropic development of such non-linear behaviours, and how they depend on loading mode, tensile samples of a 3D-woven layer-to-layer angle interlock carbon-fibre reinforced epoxy composite are tested experimentally (data shared publicly). More specifically, specimens are cut and tested at orientations of 0°, 15°, 30°, 45° and 90° relative to the direction of the warp yarns. The samples are tested cyclically by loading and unloading them at progressively higher displacement values. By monitoring the reduction in stiffness and the development of permanent strains it is possible to identify material parameter values used to calibrate an anisotropic macroscale elasto-plastic damage model. The model shows promising agreement with the experimental results.3d纺织品增强复合材料具有几个工程优势。然而,它们复杂的纱线结构也创造了一种具有许多非线性行为和特征的材料,需要理解这些行为和特征,以便有效地使用它们。为了证明这种非线性行为的各向异性发展,以及它们如何依赖于加载模式,我们对3d编织层对层角联锁碳纤维增强环氧复合材料的拉伸样品进行了实验测试(数据公开)。更具体地说,试样在相对于经纱方向的0°、15°、30°、45°和90°方向上切割和测试。通过在逐渐增大的位移值下加载和卸载,对样品进行循环测试。通过监测刚度的降低和永久应变的发展,可以确定用于校准各向异性宏观弹塑性损伤模型的材料参数值。该模型与实验结果吻合较好。Composites Part B: EngineeringIon-induced electrospinning of hierarchical spiderweb-like bioscaffoldsYayun Wang, Zhigang Chen, Jurui Liu, Zhongqing Wu, Xiao Wang, Junfeng Chen, Hongjing Zhang, Mingming Wu, Kang Yang, Changshun Ruan, Bin Wangdoi:10.1016/j.compositesb.2024.111729离子诱导的分层网状生物支架的静电纺丝Tissue engineered scaffolds need to possess various functionalities, including biocompatibility, mechanical support, bioactivity, and vascularization. The design and fabrication of bioscaffolds to attain mutual coordination among these functionalities with minimal processing complexity are a highly challenging but rewarding task. In this study, a simple, effective one-step electrospinning method was developed to fabricate hierarchical spiderweb-like bioscaffolds that achieve both superior biological and mechanical functionalities. By incorporating ionic drugs of deferoxamine mesylate and lithium chloride, the spiderweb-inspired structures with adjustable coverages (up to 100 %) were successfully created, imparting the fibrous bioscaffolds with remarkable tensile strengths (∼88.28 MPa). The strengthening mechanisms endowed by the spiderweb structure in optimizing stress distribution to delay damage and enhance load-bearing ability were elucidated through finite element simulations. Furthermore, this hierarchical spiderweb-like bioscaffold demonstrated favorable biological characteristics, including biocompatibility, osteogenesis, angiogenesis, and hemostasis. The presence of the nano-spiderweb structures significantly improved cell adhesion and differentiation on the scaffold and increased the spreading area of cells by 2–3 times. The dual-drug loaded bioscaffolds with full coverages of the spiderweb structure exhibited the least amount of bleeding (45.33 ± 27.47 mg) and the fastest hemostasis speed (82 ± 8.19 s) in the hemostasis test, compared to the control group. Overall, the outstanding performance makes the developed bioscaffolds a promising alternative for tissue repair and regeneration in the field of tissue engineering.组织工程支架需要具备多种功能,包括生物相容性、机械支持、生物活性和血管化。设计和制造生物支架,以最小的加工复杂性实现这些功能之间的相互协调,是一项极具挑战性但有益的任务。在这项研究中,我们开发了一种简单、有效的一步静电纺丝方法来制造分层的蛛网状生物支架,这种生物支架具有优越的生物和机械功能。通过加入甲磺酸去铁胺和氯化锂离子药物,成功创建了具有可调节覆盖率(高达100%)的蜘蛛网式结构,赋予纤维生物支架显著的拉伸强度(~ 88.28 MPa)。通过有限元模拟,阐明了蛛网结构在优化应力分布、延缓损伤、提高承载能力方面所赋予的强化机制。此外,这种分层蜘蛛网状生物支架表现出良好的生物学特性,包括生物相容性、成骨、血管生成和止血。纳米蜘蛛网结构的存在显著改善了细胞在支架上的粘附和分化,细胞的扩散面积增加了2-3倍。全覆盖蜘蛛网结构的双药负载生物支架在止血试验中出血量最少(45.33±27.47 mg),止血速度最快(82±8.19 s)。综上所述,所开发的生物支架在组织工程领域具有良好的组织修复和再生前景。Composites Science and TechnologySynthesis of magnesium ferrite decorated MXene composites with broadband and high-efficiency microwave dissipation performanceLijuan Nie, Zongli Wan, Ruiwen Shudoi:10.1016/j.compscitech.2024.110764 具有宽带高效微波耗散性能的铁氧体镁修饰MXene复合材料的合成As an emerging material, MXene has attracted wide interest in the field of microwave absorption due to its unique two-dimensional stratified structure and high electrical conductivity. However, the non-magnetic nature of MXene and the inherent agglomeration phenomenon are a huge obstacle to meeting the performance requirements of novel microwave absorbers. The introduction of magnetic components is an effective strategy to improve the microwave dissipation capacity of MXene. Herein, MXene/MgFe2O4 composites with dielectric and magnetic components were prepared by the solvothermal synthesis and subsequent hydrothermal reaction. The results of microscopic morphology analysis demonstrated that a special entangled structure was formed between MgFe2O4 and wrinkled MXene. Furthermore, by adjusting the weight concentration of MXene, the impedance matching of the absorbers could be regulated to optimize its microwave dissipation capacity. Remarkably, the as-fabricated MXene/MgFe2O4 composite with a weight concentration of 2 mg/mL exhibited excellent microwave dissipation capacity. Specifically, the minimum reflection loss was as low as -53.1 dB and the maximum effective absorption bandwidth reached 7.44 GHz, which covered a part of X-band and the whole Ku-band. The significant improvement in microwave dissipation performance could be attributed to the optimization of magnetodielectric synergistic effect, resulting in improved impedance matching. It was expected that the research results of this paper would provide reference for the preparation of MXene-based composites as efficient and broadband microwave absorbers.MXene作为一种新兴材料,由于其独特的二维分层结构和高导电性,在微波吸收领域引起了广泛的关注。然而,MXene的非磁性和固有的团聚现象是满足新型微波吸收剂性能要求的巨大障碍。磁性元件的引入是提高MXene微波耗散能力的有效策略。通过溶剂热合成和水热反应制备了具有介电和磁性组分的MXene/MgFe2O4复合材料。微观形貌分析结果表明,MgFe2O4与皱褶MXene之间形成了一种特殊的纠缠结构。此外,通过调节MXene的质量浓度,可以调节吸波器的阻抗匹配,从而优化其微波耗散能力。值得注意的是,重量浓度为2 mg/mL的MXene/MgFe2O4复合材料具有优异的微波耗散能力。其中,最小反射损耗低至-53.1 dB,最大有效吸收带宽达到7.44 GHz,覆盖了部分x波段和整个ku波段。微波耗散性能的显著提高可归因于磁介质协同效应的优化,从而改善了阻抗匹配。期望本文的研究结果能为制备高效宽带微波吸收剂mxene基复合材料提供参考。π-Conjugated Metallo-copolymer/SWCNT Composites for High Performance Thermoelectric GeneratorsLifen Chen, Zelin Sun, Jiahua Li, Mei-Tung Lau, Jibin Sun, Deqing Zhang, Wai-Yeung Wong, Linli Xudoi:10.1016/j.compscitech.2024.110768 高性能热电发电机用π共轭金属共聚物/ swcnts复合材料Organic materials have attracted extensive attention in flexible thermoelectric generators due to their solution processability, low thermal conductivity and high flexibility. However, their thermoelectric performances are still far behind those of the inorganic counterparts (e.g. Bi2Te3, PbTe and other related alloys). Here, by virtue of the dual advantages of both inorganic and organic materials, three Pt(II)-containing diketopyrrolopyrrole (DPP) based donor−acceptor (D−A)-type π-conjugated metallo-copolymers (P1Pt, P2Pt and P3Pt) are designed and synthesized, and they are compared with their control copolymers without Pt(II)-coordination (P1, P2 and P3). It is shown that Pt(II) centers and copolymerized molecular structures play important roles in tuning the bandgap and coplanarity. A large Fermi level shift is observed after doping with single-walled carbon nanotubes (SWCNTs) in the copolymers. As expected, the introduction of Pt(II)-side chains and doping of SWCNTs into copolymers could significantly improve the power factor (PF), which reaches the highest value of 276.5±26.6 μW·m-1·K-2 with P3Pt/60 wt% SWCNTs. The corresponding p-type thermoelectric generator exhibits a large output power of up to 0.55 μW under a 109 K temperature gradient. Our results can provide a pathway for designing and preparing efficient thermoelectric materials and flexible thermoelectric generators.有机材料具有溶液可加工性、低导热性和高柔韧性等优点,在柔性热电发电机中引起了广泛的关注。然而,它们的热电性能仍然远远落后于无机对应物(例如Bi2Te3, PbTe和其他相关合金)。本文利用无机材料和有机材料的双重优势,设计合成了三种含Pt(II)二酮吡咯(DPP)基供体-受体(D - A)型π共轭金属共聚物(P1Pt、P2Pt和P3Pt),并与不含Pt(II)配位的对照共聚物(P1、P2和P3)进行了比较。结果表明,Pt(II)中心和共聚分子结构在调节带隙和共面性方面起着重要作用。在共聚物中掺杂单壁碳纳米管(SWCNTs)后,观察到较大的费米能级位移。正如预期的那样,在共聚物中引入Pt(II)侧链并掺杂SWCNTs可以显著提高共聚物的功率因数(PF),当P3Pt/60 wt% SWCNTs时,功率因数达到276.5±26.6 μW·m-1·K-2的最大值。在109 K温度梯度下,p型热电发生器的输出功率可达0.55 μW。我们的研究结果为设计和制备高效热电材料和柔性热电发生器提供了途径。来源:复合材料力学仿真Composites FEM

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