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【新文速递】2024年8月23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 2 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 1 篇

Composite Structures

A review of extrusion-based additive manufacturing of multi-materials-based polymeric laminated structures

Imran Khan, Imad Barsoum, Muhammad Abas, Ans Al Rashid, Muammer Koç, Muhammad Tariq

doi:10.1016/j.compstruct.2024.118490

多材料基聚合物层合结构的挤出增材制造研究进展

Additive Manufacturing (AM) techniques have garnered significant attention for their applicability in fabricating intricate and complex geometries, end-user products, expediting prototyping processes, creating functional devices, sensors, and metamaterial structures for various applications. A relatively nascent area of exploration within this realm is using Extrusion-based Additive Manufacturing (EbAM) to produce multi-materials-based laminated, clad, or panel-based polymer composite structures. This study delves into recent advancements in clad, laminated, or panel-based polymer composite fabrication through EbAM, offering a comprehensive review of relevant literature. The examination encompasses a brief literature review, exploring potential applications for the fabricated composites, scrutinizing 3-dimensional printing (3DP) conditions, identifying optimum 3DP parameters, and assessing the resultant mechanical and functional properties. Furthermore, the article addresses the drawbacks and deficiencies found in existing studies, highlighting areas requiring attention in future research endeavours. A culmination of the review involves discussing the identified future research gaps in the fabrication of laminated composites via EbAM. By synthesizing insights from recent works and elucidating accomplishments and limitations, this article contributes to the collective understanding of the evolving landscape of EbAM techniques for multi-materials-based polymer laminated composite structure (LCS) and lattice structures fabrication.

增材制造(AM)技术因其在制造复杂几何形状、最终用户产品、加速原型制作过程、创建功能器件、传感器和各种应用的超材料结构方面的适用性而受到广泛关注。在这一领域中,一个相对新兴的探索领域是使用基于挤压的增材制造(EbAM)来生产基于多材料的层压、覆层或基于面板的聚合物复合材料结构。本研究通过EbAM深入研究了覆层、层压或板基聚合物复合材料制造的最新进展,并对相关文献进行了全面的回顾。该研究包括简要的文献综述,探索制造复合材料的潜在应用,仔细检查三维打印(3DP)条件,确定最佳的3DP参数,并评估由此产生的机械和功能特性。此外,本文还指出了现有研究中的缺陷和不足,强调了未来研究工作中需要注意的领域。回顾的高 潮包括讨论通过EbAM制造层压复合材料确定的未来研究差距。通过对近期研究成果的综合分析,以及对研究成果和局限性的阐述,本文有助于对基于多材料的聚合物层压复合材料结构(LCS)和晶格结构制造的EbAM技术的发展前景进行集体理解。


Interaction of multiple micro-defects on the strength and failure mechanism of UD composites by computational micromechanics

Chenyang Xie, Yaowei Meng, Junzhen Chen, Zhiyong Zhao, Junbiao Wang, Jianjun Jiang, Yujun Li

doi:10.1016/j.compstruct.2024.118492

多个微缺陷相互作用对UD复合材料强度及破坏机制的计算细观力学研究

The mechanical properties of unidirectional fiber-reinforced plastic (UD-FRP) are affected by a variety of micro-defects, such as random fiber arrangement, fiber misalignment and micro-voids. This study aims to investigate how these multiple micro-defects interact with each other and how they affect the strength and failure mechanisms of UD-FRP by means of computational micromechanics. The composite behavior was simulated by the finite element analysis of a representative volume element of the composite microstructure in which the random distribution of fibers, the micro-voids, and the fiber misalignment are explicitly included. Both matrix and interface failure were considered for the loadings of transverse tension/compression, longitudinal compression, transverse/ longitudinal shear, and their combination. It was found that these three micro-defects significantly weakened the compressive strength of UD-FRP along the longitudinal direction. Especially, the fiber misalignment magnified the effect of fiber arrangement, while the micro-voids reduce the effect. Besides, the fiber arrangement and micro-voids significantly weakened the tensile and compressive strength of UD-FRP along the transverse direction, but their interaction effect was not obvious. Moreover, transverse and longitudinal shear strength are significantly affected by micro-voids, but only longitudinal shear is affected by geometric fiber arrangement, and this effect is also weakened by micro-voids. Finally, the damage envelope under the combined longitudinal compression and transverse loads was obtained and compared with the Tsai-Wu failure criterion. The results showed that the Tsai-Wu criteria can provide an effective estimation for the failure locus under this biaxial loading condition

单向纤维增强塑料(UD-FRP)的力学性能受到多种微缺陷的影响,如纤维无序排列、纤维错位和微孔洞。本研究旨在通过计算细观力学的方法研究这些多个微缺陷如何相互作用,以及它们如何影响UD-FRP的强度和破坏机制。采用具有代表性的复合材料微观结构体积元进行有限元分析,明确考虑了纤维的随机分布、微空隙和纤维的错位等因素,模拟了复合材料的性能。横向拉伸/压缩、纵向压缩、横向/纵向剪切及其组合荷载均考虑基体破坏和界面破坏。结果表明,这3个微缺陷沿纵向显著削弱UD-FRP的抗压强度。其中,光纤错位放大了光纤排列的效果,而微孔的存在则降低了光纤排列的效果。此外,纤维排列和微孔沿横向显著削弱UD-FRP的抗拉和抗压强度,但它们的相互作用不明显。此外,微孔洞对横向和纵向抗剪强度均有显著影响,但纤维几何排列只对纵向抗剪强度有影响,微孔洞也削弱了这种影响。最后,得到了纵向压缩和横向荷载联合作用下的损伤包络线,并与Tsai-Wu破坏准则进行了比较。结果表明,Tsai-Wu准则可以有效地估计双轴加载条件下的破坏轨迹


Quasi-brittle fracture criterion of CFRP with shallow surface scratch based on boundary effect model

Pingping Luo, Wei Shen, Lifeng Chen, Qian Li, Zijia Yao, Lvtao Zhu

doi:10.1016/j.compstruct.2024.118464

基于边界效应模型的CFRP浅表面划伤准脆性断裂准则

This study investigates the quasi-brittle fracture parameters of carbon fiber composites with shallow surface scratches by considering single-layer prepreg thickness as the characteristic composite microstructure. Three-point bending fracture tests were conducted on single-edge notched specimens of various-sized carbon fiber composites. The boundary effect model was employed to establish the relationship between the microstructure and macroscopic mechanical characteristics of carbon fiber composites. The maximum fracture load was used to determine the quasi-brittle fracture characteristics. By employing normal distribution analysis, the tensile strength and fracture toughness of each specimens were determined as ft = 453.28 MPa and KIC= 22.2 MPa√m, respectively. The analysis results exhibited an error of only 0.39 % compared to the least-squares fit, and encompassed almost all discrete points of the specimens within a 95 % reliability range. Using standard laboratory dimensions, fracture intervals for different notched depths at the same thickness can be predicted. Furthermore, the fracture parameters demonstrated an increasing trend within a certain range as the crack-thickness ratio increases, which aligns with the theoretical findings.

本研究将单层预浸料厚度视为复合材料微观结构的特征,研究了表面有浅划痕的碳纤维复合材料的准脆性断裂参数。对不同尺寸碳纤维复合材料的单边缺口试样进行了三点弯曲断裂试验。采用边界效应模型建立了碳纤维复合材料微观结构与宏观力学特性之间的关系。最大断裂载荷用于确定准脆性断裂特征。通过正态分布分析,确定每个试样的抗拉强度和断裂韧性分别为 ft = 453.28 MPa 和 KIC= 22.2 MPa√m。与最小二乘法拟合相比,分析结果的误差仅为 0.39%,几乎涵盖了试样的所有离散点,可靠度在 95% 的范围内。利用标准实验室尺寸,可以预测相同厚度下不同缺口深度的断裂区间。此外,随着裂纹厚度比的增加,断裂参数在一定范围内呈上升趋势,这与理论研究结果一致。


Ultimate strength prediction of composite laminates containing straight-sided holes, scarfed holes, and bonded repairs

Stephen Daynes, Raj Das

doi:10.1016/j.compstruct.2024.118512

包含直边孔、斜切孔和粘合修补的复合材料层压板的极限强度预测

Scarfed repairs are well suited to load carrying aerospace structures because they can improve the strength of a damaged composite laminate while maintaining a smooth aerodynamic profile. However, the strength prediction of such composite repairs is challenging, with strength depending upon the size and shape of the geometric features causing stress concentrations and the laminate stacking sequence. New semi-analytical and finite element analysis strength models are presented along with experimental verification for laminates containing circular and elliptically shaped straight-sided holes, scarfed holes, and adhesively bonded repairs. The new semi-analytical model for open hole ultimate strength is an extension of the point stress criterion. The model can estimate the characteristic damage length based on material properties, stacking sequence, hole shape, and hole size. Strength predictions for adhesively bonded repairs are also presented. The semi-analytical models are comparable in accuracy to the more computationally expensive continuum damage finite element models for the wide range of panels tested, and both model predictions are in close correlation with experimental results.

斜切修复非常适合于承载载荷的航空航天结构,因为它们可以在保持光滑气动外形的同时提高受损复合材料层压板的强度。然而,这种复合材料修复的强度预测具有挑战性,其强度取决于引起应力集中的几何特征的大小和形状以及层压板的堆叠顺序。提出了新的半解析和有限元分析强度模型,并对含有圆形和椭圆形直边孔、斜切孔和粘接修复的层合板进行了实验验证。新的裸眼极限强度半解析模型是对点应力准则的扩展。该模型可以根据材料特性、堆积顺序、孔洞形状和孔洞尺寸来估计特征损伤长度。粘接修复的强度预测也被提出。半解析模型在精度上可与计算成本较高的连续损伤有限元模型相媲美,并且两种模型的预测结果与实验结果密切相关。


Composites Part A: Applied Science and Manufacturing

Damage evolution analysis of C/SiC screwed/bonded hybrid joints based on in-situ micro-CT technique

Bingyao Li, Jingran Ge, Zhenqiang Wu, Xiaodong Liu, Binbin Zhang, Shuwei Zhao, Zengwen Wu, Jun Liang

doi:10.1016/j.compositesa.2024.108417

基于原位微ct技术的C/SiC螺纹/粘结复合接头损伤演化分析

Due to own good high temperature mechanical properties, the C/SiC screwed/bonded hybrid joints are considered as an important development direction of vehicle connection structures. However, the difficulty of directly monitoring the interior of the hybrid joints during the bearing presents a potential challenge to the structural damage assessment. In this study, the damage process of the hybrid joints subjected to tensile loading was monitored and characterized based on the in-situ micro-CT technique. The intrinsic relationship between the mechanical responses of the hybrid joints and the local damage evolution was elucidated by observing the variation of the deposited SiC void volume at the overlap interface. The dual inhomogeneity of SiC bonding layer was quantitatively characterized utilizing the average failure rate and determination coefficient. The coupling influence mechanism of prefabricated bottom hole size and online connection process on the final assembly clearance was revealed.

C/SiC螺纹/粘接混合接头由于具有良好的高温力学性能,被认为是汽车连接结构的重要发展方向。然而,在承载过程中对混合接头内部进行直接监测的难度给结构损伤评估带来了潜在的挑战。本研究基于原位微ct技术对复合接头在拉伸载荷作用下的损伤过程进行了监测和表征。通过观察叠合界面沉积SiC空洞体积的变化,阐明了杂化接头的力学响应与局部损伤演化之间的内在关系。利用平均失效率和确定系数定量表征了碳化硅键合层的双重不均匀性。揭示了预制井底尺寸与在线连接工艺对最终装配间隙的耦合影响机理。


Asymmetric electrical-magnetic composite foams with oriented cells fabricated by supercritical CO2 foaming and thermal stretching for efficient absorption dominated electromagnetic interference shielding

Jinghao Qian, Haiying Zhan, Hao-Yang Mi, Xiao Li, Weipeng Zhong, Xinchao Wang, Chuntai Liu, Changyu Shen

doi:10.1016/j.compositesa.2024.108428

 

采用超临界CO2发泡和热拉伸技术制备具有定向孔的非对称电磁复合泡沫材料,用于高效吸收为主的电磁干扰屏蔽

Asymmetric composite foams (TCFAs) based on thermoplastic polyurethane (TPU) containing carbon nanotubes (CNTs) and Fe3O4-decorated reduced graphene oxide (Fe3O4@rGO) electrical-magnetic dual networks with oriented cell structures and a silver layer were fabricated through supercritical carbon dioxide foaming, thermal stretching and a knife coating process. The oriented cells prolonged the electromagnetic (EM) wave transmission path and induced more multiple reflections, and the asymmetric silver layer enabled a special “absorption-reflection-reabsorption” mechanism, which contributed to a high electromagnetic interference (EMI) shielding effectiveness (SE) of 89.5 dB with an A value of 0.748 at a relatively low total filler content of 1.784 vol%. By regulating the oriented cell structure and the incorporation of asymmetric design, the TCFA-1 achieved 10 times improvement in EMI SET with a low EMI SER of 1.27 dB. This work offers new insights into the design and fabrication strategies for high performance absorption-dominated EMI shielding foams.

采用超临界二氧化碳发泡、热拉伸和刀涂工艺制备了以碳纳米管(CNTs)和fe3o4修饰的还原性氧化石墨烯(Fe3O4@rGO)为基体的热塑性聚氨酯(TPU)为基体的非对称复合泡沫材料(TCFAs)。定向电池延长了电磁波的传输路径,引起了更多的多次反射,不对称银层实现了特殊的“吸收-反射-重吸收”机制,这使得在相对较低的填料含量为1.784 vol%的情况下,电磁干扰屏蔽效率(SE)达到89.5 dB, a值为0.748。通过调节定向单元结构和非对称设计,TCFA-1的EMI SET性能提高了10倍,EMI SER低至1.27 dB。这项工作为高性能吸收型电磁干扰屏蔽泡沫的设计和制造策略提供了新的见解。


Composites Part B: Engineering

Tailored thermoelectric performance of poly(phenylene butadiynylene)s/carbon nanotubes nanocomposites towards wearable thermoelectric generator application

Wei-Chen Shih, Megumi Matsuda, Kazuki Konno, Po-Shen Lin, Tomoya Higashihara, Cheng-Liang Liu

doi:10.1016/j.compositesb.2024.111779

 

面向可穿戴热电发电机应用的聚苯丁二烯/碳纳米管纳米复合材料的热电性能

In this study, two conjugated polymers (CPs) featuring poly(phenylene butadiynylene) (PPB) were meticulously synthesized and composited with single-walled carbon nanotubes (SWCNTs) to investigate their thermoelectric properties and fabricate wearable thermoelectric generators (TEGs). These CPs, designated as P1 and P2, were tailored with distinct side chain configurations by incorporating 2-butyloctyloxy and 6-(methyldioctylsilyl)hexyloxy groups, respectively. Notably, P2, characterized by longer side chains with branchpoints farther from the backbone, exhibited planar backbone structure and enhanced solubility, consequently engendering stronger π–π interaction with SWCNTs and facilitating the disperse of SWCNTs through polymer wrapping at bundle surface. Such characteristics therefore contributed to the superior thermoelectric performances of the P2/SWCNTs nanocomposite, yielding a higher power factor (PF) of 216.5 μW m−1 K−2 for the spin-coated film. Furthermore, the corresponding wearable TEGs, which were constructed through spray-coating with 14 legs, resulted in an output power of approximately 49.6 nW under a temperature difference of 25 K, exhibiting successful harvesting of waste heat. Further applications also demonstrated operational efficacy under diverse conditions. These findings not only underscored the significance of side chain engineering in tailoring the thermoelectric properties of CP/SWCNTs nanocomposites but also demonstrated the feasibility of fabricating high-performance wearable thermoelectric devices applicable in versatile contexts.

在本研究中,精心合成了两种具有聚苯丁二炔(PPB)特征的共轭聚合物(CPs),并将其与单壁碳纳米管(SWCNTs)复合,以研究其热电性能并制造可穿戴热电发生器(teg)。这些CPs分别被命名为P1和P2,它们分别含有2-丁基氧基和6-(甲基二辛基硅基)己氧基,具有不同的侧链构型。值得注意的是,侧链较长且支点离主链较远的P2具有平面主链结构,其溶解性增强,从而与SWCNTs产生更强的π -π相互作用,促进SWCNTs通过束表面的聚合物包裹分散。因此,这些特性有助于P2/SWCNTs纳米复合材料的优越热电性能,使自旋涂层薄膜的功率因数(PF)达到216.5 μW m−1 K−2。此外,相应的可穿戴teg通过喷涂构建,具有14条腿,在温差为25 K的情况下,输出功率约为49.6 nW,成功地收集了废热。进一步的应用也证明了在不同条件下的运行效率。这些发现不仅强调了侧链工程在调整CP/SWCNTs纳米复合材料热电性能方面的重要性,而且证明了制造适用于多种环境的高性能可穿戴热电器件的可行性。


Composites Science and Technology

Ultrahigh absorption dominant EMI shielding polyimide composites with enhanced piezoelectric property

Hui Li, Jianwei Li, Wei Chu, Jun Lin, Pengfei He, Wei Fan, Qiangli Zhao

doi:10.1016/j.compscitech.2024.110820

增强压电性能的超高吸收优势屏蔽聚酰亚胺复合材料

Piezoelectric sensors have been widely used in wearable electronic devices with improved integration, which is prone to cause electromagnetic interference (EMI) pollution and affects its operation stability. How to design the materials with integrated piezoelectric sensing and EMI shielding performance is of great significance. In this paper, the Fe3O4@PPy/PINF (FPN) composite film was prepared by depositing pyrrole (Py) on the surface of Fe3O4 nanoparticles and combining it with polyimide (PI) nanofibrous membrane via vacuum-assisted suction filtration. In addition, after encapsulation with a highly soluble fluorine-containing polyimide (FPI) resin, a structurally stable FPI-Fe3O4@PPy/PINF (PFPN) composite film was obtained. The prepared PFPN composites show excellent EMI shielding effectiveness (44.58 dB) through the secondary reflection and multiple absorption effects. Remarkably, the value of the absorption coefficient A can reach 0.74, showing outstanding absorption characteristics. In addition, PFPN composite film also shows unexpected piezoelectric properties with high sensitivity of S = 0.8, short response (25 ms) and recovery (45 ms) time. Its piezoelectric output can reach 4.2 V with stable cyclic output property (> 15000 times). This kind of composite film with ultra-low reflection characteristics and favorable piezoelectricity presents a wide range of potential applications in the self-powered wearable electronic fields.

压电传感器广泛应用于集成度较高的可穿戴电子器件中,易产生电磁干扰污染,影响其工作稳定性。如何设计集压电传感和电磁干扰屏蔽性能于一体的材料具有重要意义。本文将吡咯(Py)沉积在Fe3O4纳米颗粒表面,并通过真空辅助吸滤将其与聚酰亚胺(PI)纳米纤维膜结合,制备了Fe3O4@PPy/PINF (FPN)复合膜。此外,用高溶性含氟聚酰亚胺(FPI)树脂包封后,获得了结构稳定的FPI-Fe3O4@PPy/ PFPN复合膜。通过二次反射和多次吸收效应,制备的PFPN复合材料具有良好的电磁干扰屏蔽效果(44.58 dB)。值得注意的是,其吸收系数A可达0.74,表现出优异的吸收特性。此外,PFPN复合膜还表现出意想不到的压电性能,具有S = 0.8的高灵敏度、短响应(25 ms)和45 ms的恢复时间。其压电输出可达4.2 V,循环输出性能稳定(> 15000次)。这种复合薄膜具有超低反射特性和良好的压电性,在自供电可穿戴电子领域具有广泛的应用前景。




来源:复合材料力学仿真Composites FEM
ACTMechanicalAdditiveMAGNET断裂复合材料航空航天汽车电子增材ADS裂纹理论电机材料试验装配
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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

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 StructuresNumerical assessment of fiber distribution effects on strain-hardening cement composites using a rate-dependent Voronoi-Cell-Lattice-ModelJi Woon Park, Bonhwi Choo, Jeongun Lee, Yun Mook Limdoi: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 crackWenzhi Yang, Zengtao Chendoi: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 matrixJeong Hwan Kim, Dongwon Ha, Hoil Choi, Gun Jin Yundoi: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 bridgingQingfeng Duan, Haixiao Hu, Dongfeng Cao, Wei Cai, Junkang Xia, Shuxin Lidoi: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 ManufacturingEnhancing interfacial performance and fracture toughness of carbon fibre reinforced thermoplastic compositesYao Chen, Vishnu Prasad, Miray Yasar, Neal Murphy, Alojz Ivankovicdoi: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: EngineeringStretch-Steering of Highly Aligned Discontinuous Fiber Tape with Automated Fiber PlacementAlexander Legenstein, Lukas Fussel, Dirk Heider, John W. Gillespie, Thomas A. Cenderdoi: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 TechnologyUnlocking thermal management capacity: Optimized organic-inorganic hybrid shell phase change microcapsules with controllable structure and enhanced conductivityXueting Wang, Huaxin Chen, Dongliang Kuang, Xiao Huan, Zhengyuan Zeng, Cong Qi, Shanjian Han, Guanyu Lidoi: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

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