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【新文速递】2023年10月5日固体力学SCI期刊最新文章

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今日更新:Journal of the Mechanics and Physics of Solids 1 篇,Mechanics of Materials 1 篇

Journal of the Mechanics and Physics of Solids

Bending the rules: Strain accommodation in layered crystalline solids through nanoscale buckling over dislocations

Gruber Jacob, Plummer Gabriel, Tucker Garritt J.

doi:10.1016/j.jmps.2023.105450

弯曲规则:通过纳米级位错屈曲实现层状晶体固体的应变容纳

Basal dislocations and ripplocations both offer explanations for the deformation of layered crystalline solids in response to compressive strain. Existing work, however, presents no clear definition of a ripplocation and the distinction between these two mechanisms remains unclear. Molecular dynamics simulations in graphite and modified graphitic models reveal that equivalent additional half-planes of material can induce both dislocations and ripplocations. In this work, we find that ripplocations are essentially an elastic buckling phenomenon operating at the atomic scale, rather than a discrete crytallographic defect. Dislocation core confinement produces incommensurate planar elastic strains with sufficient energy to trigger a buckling instability that transfers strain energy to the surrounding lattice. The interplay between incommensurate strain and buckling is a quasi-continuum phenonemon where both mechanisms may accommodate arbitrary disregistry, not only the discrete values accommodated by perfect or partial basal dislocations. The mechanistic transition depends critically on the atomic-scale interfacial energies between layers and the continuum elastic behavior of the bulk material. Buckling is possible, though unfavorable, in the MAX phase Ti3AlC2 and systems of multiple layers buckle at lower strains than only a single layer. These extensions of the ripplocation model in van der Waals layered solids suggest that nanoscale elastic buckling potentially plays a role in the deformation of a wide range of layered crystalline systems in response to common mechnical configurations.

基底位错和波状位错都能解释层状晶体固体在压缩应变作用下的变形。然而,现有研究并未给出涟漪位错的明确定义,这两种机制之间的区别仍不清楚。石墨和改良石墨模型的分子动力学模拟显示,等效的附加半平面材料既能诱发位错,也能诱发波纹位错。在这项工作中,我们发现波状位错本质上是一种在原子尺度上运行的弹性屈曲现象,而不是一种离散的晶体学缺陷。位错核心束缚会产生具有足够能量的不可比平面弹性应变,从而引发屈曲不稳定性,将应变能量传递到周围晶格。不相称应变和屈曲之间的相互作用是一种准连续现象,在这种现象中,两种机制都可以容纳任意的偏析,而不仅仅是完全或部分基底位错所容纳的离散值。机理转换在很大程度上取决于层间原子尺度的界面能量和块体材料的连续弹性行为。在 MAX 相 Ti3AlC2 中,屈曲是可能的,尽管是不利的。而多层体系在较低应变下的屈曲程度要低于单层体系。范德瓦尔斯层状固体中波纹定位模型的这些扩展表明,纳米级弹性屈曲可能在各种层状晶体系统的变形中发挥作用,以应对常见的技术配置。


Mechanics of Materials

Impact and adhesion mechanics of block copolymer micro-particles with a silicon substrate

Duran Salih, Kim Ara, Lee Jae-Hwang, Muftu Sinan

doi:10.1016/j.mechmat.2023.104817

嵌段共聚物微颗粒与硅衬底的冲击和粘附力学原理

Deformation of a two-phase block copolymer (BCP) during high velocity impacts is studied experimentally and theoretically with an aim to use this material in cold spray (CS) additive manufacturing. Micron scale (10–20 μm) spherical particles of polystyrene-block-polydimethylsiloxane (PS-b-PDMS) are impacted on a silicon substrate by using a laser-induced projectile impact test (LIPIT) setup with impact velocities in the range of 50–600 m/s. Experiments indicate that polymer particles adhere to the substrate when their impact velocities fall within the range of 140–500 m/s. A constitutive model that accounts for the effects of both strain rate and temperature on the mechanical behavior of such materials is developed. A critical energy release rate function which depends on the surface temperature and rate of separation is formulated and used in a cohesive zone model (CZM) to model bonding of the BCPs on the substrate. The model parameters are calibrated by comparing the deformed and computed deformed particle shapes and coefficient of restitution values of the rebounding particles. Simulations show that the particles experience ultra-high strain rates (>104 s−1), large deformation, and temperature elevation due to plastic dissipation and interfacial friction. The outer rim of the contact interface is predicted to experience temperature levels above the glass transition temperature of the PS-domain of the BCP. Bonding is correlated with increase of contact area, plastic dissipation and temperature rise in the interface.

通过实验和理论研究了双相嵌段共聚物(BCP)在高速冲击过程中的变形,目的是将这种材料用于冷喷(CS)快速成型制造。微米级(10-20μm)使用激光诱导弹丸冲击试验(LIPIT)装置,以 50-600 m/s 的冲击速度将聚苯乙烯-块状-聚二甲基硅氧烷(PS-b-PDMS)球形颗粒冲击到硅基底上。实验表明,当冲击速度在 140-500 米/秒范围内时,聚合物颗粒会粘附在基底上。我们建立了一个应变率和温度对这种材料的机械行为都有影响的构成模型。制定了一个取决于表面温度和分离率的临界能量释放率函数,并将其用于内聚区模型(CZM),以模拟 BCP 在基体上的粘合。通过比较变形颗粒和计算变形颗粒的形状以及反弹颗粒的恢复系数值,对模型参数进行了校准。模拟结果表明,由于塑性耗散和界面摩擦,颗粒经历了超高应变率(>104 s-1)、大变形和温度升高。据预测,接触界面外缘的温度水平将高于 BCP 的 PS 域的玻璃化转变温度。粘合与接触面积增加、塑性耗散和界面温度升高相关。


来源:复合材料力学仿真Composites FEM
ACTMechanicalAdditiveSystemDeform理论材料分子动力学试验
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首次发布时间:2024-11-03
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【新文速递】2023年10月1日复合材料SCI期刊最新文章

今日更新:Composite Structures 1 篇,Composites Part A: Applied Science and Manufacturing 7 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 2 篇Composite StructuresConfinement Of Masonry Columns With Frcm: A New Confined Strength Formulation And Experimental ValidationFaleschini Flora, Toska Klajdidoi:10.1016/j.compstruct.2023.117587用 Frcm 对砌体柱进行约束:新的约束强度公式和实验验证In this work, a wide experimental dataset about the axial behavior of masonry columns confined with Fiber Reinforced Cementitious Matrix (FRCM) jackets was collect, that contains the results from 226 confined specimens. Data were critically analyzed with the aim of identifying the influence of the most important parameters considered within the dataset (i.e., fibers type and number of layers, masonry type and unconfined strength, mortar type and mechanical strength, the effective lateral pressure, etc.). Further, a review of the main models proposed in different Codes and in literature was carried out, which were then applied to the dataset, highlighting some discrepancies in their predictions. Thus, a new formulation for the confined strength of masonry columns was proposed, aiming to consider also some other influencing variables such as the compressive strength of the masonry blocks and that of the mortar joint. Lastly, the validity of the proposal was verified on a new set of experimental results, which were obtained by the authors testing three scaled unconfined and confined clay brick masonry columns. Specimens were subject to monotonic axial loading under displacement control until failure, and stress and strains were monitored continuously during the test. The jacketing system was realized with one layer of glass-based FRCM (GFRCM).在这项工作中,我们收集了大量关于使用纤维增强水泥基质(FRCM)夹层限制砌体柱轴向行为的实验数据集,其中包含 226 个限制试样的结果。对数据进行了批判性分析,旨在确定数据集中考虑的最重要参数(即纤维类型和层数、砌体类型和非约束强度、砂浆类型和机械强度、有效侧压力等)的影响。此外,还对不同规范和文献中提出的主要模型进行了审查,然后将其应用于数据集,突出显示了其预测中的一些差异。因此,提出了一种新的砌体柱约束强度公式,旨在同时考虑其他一些影响变量,如砌块的抗压强度和灰浆接缝的抗压强度。最后,作者用一组新的实验结果验证了这一建议的有效性,这些结果是通过测试三根按比例制作的非受限和受限粘土砖砌体柱获得的。试样在位移控制下承受单调轴向荷载直至破坏,测试期间连续监测应力和应变。夹层系统由一层玻璃基 FRCM(GFRCM)构成。Composites Part A: Applied Science and ManufacturingA 3D objective material model for elastic-plastic damage behavior of fiber reinforced polymer compositesDing Junfeng, Zhang Li, Li Zhixing, Zheng Tao, Huang Kai, Guo Lichengdoi:10.1016/j.compositesa.2023.107804纤维增强聚合物复合材料弹塑性损伤行为的三维客观材料模型To simulate the plastic deformation and the progressive failure process of fiber reinforced polymer composites under 3D stress conditions, a new elastic-plastic damage model is proposed to satisfy the objectivity of 3D stress conditions. A new two-parameter 3D plasticity criterion and a simple non-associated flow potential, expressed by stress invariants of a transversely isotropic unidirectional (UD) lamina, are developed to characterize plastic deformation in an objective way. Moreover, the material degradation model and damage evolution laws are constructed on a matrix fracture angle-dependent coordinate system to ensure the objectivity of the continuum damage mechanics (CDM) approach. In addition, a new linear law alleviating mesh dependence is derived to govern the damage variable evolution in the elastic-plastic damage process. The effectiveness and objectivity of the proposed material model are demonstrated by a series of test cases.为了模拟三维应力条件下纤维增强聚合物复合材料的塑性变形和渐进破坏过程,提出了一种新的弹塑性破坏模型,以满足三维应力条件的客观性。通过横向各向同性单向(UD)薄片的应力不变量来表示新的双参数三维塑性准则和简单的非关联流势,从而客观地描述塑性变形。此外,还在与矩阵断裂角度相关的坐标系上构建了材料降解模型和损伤演变规律,以确保连续损伤力学(CDM)方法的客观性。此外,还推导出一种新的线性法则,以减轻网格依赖性,从而控制弹塑性损伤过程中的损伤变量演化。一系列测试案例证明了所提出的材料模型的有效性和客观性。Boron-doped copper phenylphosphate as temperature-response nanosheets to fabricate high fire-safety polycarbonate nanocompositesYu Ronghua, Wen Xin, Zhu Yue, Lou Shenghui, Li Yongjiang, Wang Shengda, Liu Jie, Tang Taodoi:10.1016/j.compositesa.2023.107812用掺硼的苯基磷酸铜作为温度响应纳米片,制造高防火安全性的聚碳酸酯纳米复合材料The application of polymer materials has provided the convenience and also bring fire risk and hazard due to intrinsic flammable property of polymers. Here we demonstrate a novel strategy using boron-doped copper phenylphosphate (BCuPP) nanosheets with temperature-response characteristics as only flame retardant for creating high fire-safety polycarbonate (PC) nanocomposites with excellent comprehensive performances. PC/BCuPP nanocomposites presents a good mechanical performance at room temperature due to the strong interfacial interaction between PC matrix and BCuPP nanosheets. Furthermore, BCuPP exhibits unique temperature-response behavior driven by fire, where fully molten boron oxide flows freely, followed by in-situ formed BPO4 to repair the defects to form a complete and continuous protective layer. So the temperature-response behavior endows PC/BCuPP nanocomposites excellent fire-safety performance with dramatical decrease in both heat release rate and total smoke production. This study offers a novel route only incorporating nanoparticles as flame retardant to create high fire-safety polymer nanocomposites.高分子材料的应用在给人们带来便利的同时,也因其固有的易燃特性而带来了火灾风险和危险。在这里,我们展示了一种新颖的策略,即利用具有温度响应特性的掺硼苯基磷酸铜(BCuPP)纳米片作为唯一的阻燃剂,来制造具有优异综合性能的高防火安全性聚碳酸酯(PC)纳米复合材料。PC/BCuPP 纳米复合材料在室温下具有良好的机械性能,这是由于 PC 基体与 BCuPP 纳米片之间具有很强的界面相互作用。此外,BCuPP 在火的驱动下表现出独特的温度响应行为,完全熔化的氧化硼自由流动,随后原位形成的 BPO4 修复缺陷,形成完整连续的保护层。因此,温度响应行为赋予了 PC/BCuPP 纳米复合材料卓越的防火安全性能,并显著降低了热释放率和总烟雾产生量。这项研究提供了一种新的途径,即只将纳米颗粒作为阻燃剂加入到高防火安全性聚合物纳米复合材料中。Largely improved interfacial adhesion and fatigue life of aramid fiber/polymer composites by developing GO enhanced eco-friendly dip-coating systemHuang Wei, Tian Chenchen, Zhao Hui, Yu Bing, Wang Wencai, Ning Nanying, Tian Mingdoi:10.1016/j.compositesa.2023.107813通过开发 GO 增强型环保浸涂系统,大幅提高芳纶纤维/聚合物复合材料的界面附着力和疲劳寿命For achieving high performance and long fatigue life of fiber-reinforced polymer composites (FRPC), a key is to construct strong interfacial bonding between fibers and polymer. Herein, an epoxy resin-based environmentally friendly dipping solution (named as MGL) for aramid fiber (AF) was newly designed and produced to obtain the same good interfacial bonding with natural rubber (NR) as that using traditional toxic resorcinol-formaldehyde-rubber latex (RFL). The H pull-out force and fatigue life of AF/NR composites treated by using the new MGL dipping system are even higher than that using RFL. Based on the theory of interface stress transfer, polyethyleneimine (PEI) modified graphene oxide (GO) was further introduced into the new dipping system, and the H pull-out force, 180° peel-out force and fatigue life of AF/NR composites largely increase by 23.8%, 26.7% and 60.7%, respectively. The H pull-out force of AF/NR composites is significantly higher than that reported in previous studies.要实现纤维增强聚合物复合材料(FRPC)的高性能和长疲劳寿命,关键在于在纤维和聚合物之间建立牢固的界面粘合。为此,新设计并生产了一种基于环氧树脂的芳纶纤维(AF)环保型浸渍液(命名为 MGL),与传统的有毒间苯二酚-甲醛-橡胶胶乳(RFL)相比,该浸渍液能获得与天然橡胶(NR)相同的良好界面粘合效果。使用新型 MGL 浸渍系统处理的 AF/NR 复合材料的 H 拉拔力和疲劳寿命甚至高于使用 RFL 的复合材料。根据界面应力传递理论,将聚乙烯亚胺(PEI)修饰的氧化石墨烯(GO)进一步引入新的浸渍体系,AF/NR 复合材料的 H 拉拔力、180° 剥离力和疲劳寿命分别大幅提高了 23.8%、26.7% 和 60.7%。AF/NR 复合材料的 H 拉拔力明显高于以往研究的结果。3D printable, anti-freezing, and rapid self-healing violet phosphorene incorporated hydrogel-based sensors for human motion detectionZhang Juan, Wang Yanen, Wei Qinghua, Li Mingyang, Chen Xiaohu, Zhou Jiayidoi:10.1016/j.compositesa.2023.107814可三维打印、抗冻、快速自愈的紫磷烯水凝胶传感器,用于人体运动检测Conductive self-healing hydrogels, as an emerging flexible material, have been extensively studied in flexible sensors which have great application potential in the field of wearable electronic devices. However, hydrogels are prone to freezing at low temperatures, resulting in reduced or even lost flexibility, conductivity and self-healing properties. Besides, manufacturing method, processing time and cost of hydrogel-based sensors remain extremely challenging, hindering their application in complex and extreme environments. The hydrogel with excellent strain-sensing properties and outstanding anti-freezing properties was fabricated by 3D printing technology and solvent displacement method. The VP-SPB-EG hydrogel has excellent anti-freezing performance (-80 ℃). In particular, this hydrogel exhibits excellent self-healing performance (120 s) at -80 ℃. In addition, VP-SPB-EG hydrogel-based has high stretchability (1850 %) and sensitivity (GF: 27.82) can be used to detect strain changes caused by human joint movements. Therefore, this flexible hydrogel-based sensor has broad application prospects for wearable devices in extreme environments.导电自愈合水凝胶作为一种新兴的柔性材料,已在柔性传感器中得到广泛研究,在可穿戴电子设备领域具有巨大的应用潜力。然而,水凝胶在低温下容易冻结,导致柔性、导电性和自愈性降低甚至丧失。此外,水凝胶传感器的制造方法、加工时间和成本仍然极具挑战性,阻碍了其在复杂和极端环境中的应用。通过三维打印技术和溶剂置换法,制备出了具有优异应变传感性能和出色抗冻性能的水凝胶。VP-SPB-EG 水凝胶具有优异的抗冻性能(-80 ℃)。特别是,这种水凝胶在-80 ℃下具有优异的自愈合性能(120 秒)。此外,VP-SPB-EG 水凝胶还具有高伸展性(1850 %)和灵敏度(GF:27.82),可用于检测人体关节运动引起的应变变化。因此,这种柔性水凝胶传感器在极端环境下的可穿戴设备中具有广阔的应用前景。Boron nitride nanosheets as precursors for 3D nano-configurations in titanium matrix composites: interfacial evolution and mechanical behaviorLiu Zhenqiang, Yang Hao, Wang Yun, Xu Zhenying, Zhang Koubao, Li Ruitaodoi:10.1016/j.compositesa.2023.107815氮化硼纳米片作为钛基复合材料中三维纳米结构的前驱体:界面演变和力学行为Boron nitride nanosheets (BNNSs) have tremendous potential as reinforcements for titanium (Ti) due to their excellent strengthening and toughening efficiency from in-situ generated 3D nano-configurations. However, the effect of interfacial evolution on the mechanical properties of the BNNSs/Ti composite remains unexplored. To this end, in this study, the interfacial structure was regulated utilizing the time-dependent reaction of BNNSs/Ti system. Its effects on mechanical behavior were studied by combining experiments and molecular dynamic simulations. BNNSs were gradually converted to 3D nano-configurations over time and finally consumed to form coarsened TiB whiskers in the TC4 matrix. The composite with 3D nano-configurations exhibited a tensile strength of 1140.5 MPa and excellent toughness of 42.9 MJ/m3. Strength improvement stems primarily from nano-interlocking, which increases dislocation density under load and improves the interfacial shear strength. The considerable toughness results from the enhanced crack resistance brought by the 3D nano-configurations.氮化硼纳米片(BNNSs)因其原位生成的三维纳米结构而具有优异的增强和增韧效率,因此作为钛(Ti)的增强材料具有巨大的潜力。然而,界面演化对 BNNSs/Ti 复合材料机械性能的影响仍有待探索。为此,本研究利用 BNNSs/Ti 系统随时间变化的反应来调节界面结构。通过结合实验和分子动力学模拟,研究了其对力学行为的影响。随着时间的推移,BNNS 逐渐转化为三维纳米结构,并最终在 TC4 基体中消耗形成粗化的 TiB 晶须。三维纳米结构的复合材料显示出 1140.5 兆帕的拉伸强度和 42.9 兆焦耳/立方米的优异韧性。强度的提高主要源于纳米交错,它增加了负载下的位错密度,提高了界面剪切强度。三维纳米结构增强了抗裂纹能力,因而具有相当高的韧性。Characterizing damage evolution of CF/PEKK composites under tensile loading through multi-instrument structural health monitoring techniquesYildirim Ceren, Emami Tabrizi Isa, Al-Nadhari Abdulrahman, Topal Serra, Beylergil Bertan, Yildiz Mehmetdoi:10.1016/j.compositesa.2023.107817通过多仪器结构健康监测技术确定 CF/PEKK 复合材料在拉伸载荷作用下的损伤演变特征This study investigates the damage behavior of autoclave consolidated carbon fiber/Polyetherketoneketone (CF/PEKK) laminates manufactured by the automated fiber placement (AFP) lay-up process. The damage evaluation of autoclave consolidated samples is studied using a multi-instrument nondestructive monitoring approach. The effect of autoclave consolidation on the microstructure of the laminate is examined via void analysis based on density measurement, thermal analysis, and optical microscopy. The results reveal that the void content is achieved as 0.46% while the degree of crystallinity increases up to 81.81% following the autoclave consolidation. Moreover, acoustic emission (AE), digital image correlation (DIC), and infrared thermography (IRT) results are cross-correlated to further understand the damage development. The evolution of clustered AE data during mechanical loading is used to divide the failure of the laminate into two stages, each of which signifies a different dominancy in failure modes. Scanning electron microscopy (SEM) is employed to associate damage characteristics with failure monitoring techniques.本研究调查了采用自动纤维铺放 (AFP) 工艺制造的高压固化碳纤维/聚醚酮酮 (CF/PEKK) 层压板的损伤行为。采用多仪器无损监测方法对高压固化样品的损伤评估进行了研究。通过基于密度测量、热分析和光学显微镜的空隙分析,研究了高压釜固结对层压板微观结构的影响。结果表明,在高压固化后,空隙含量为 0.46%,而结晶度则增加到 81.81%。此外,声发射(AE)、数字图像相关(DIC)和红外热成像(IRT)结果相互关联,以进一步了解损伤的发展。在机械加载过程中,AE 数据的聚类演变被用来将层压板的失效分为两个阶段,每个阶段在失效模式中占据不同的主导地位。扫描电子显微镜(SEM)用于将损伤特征与失效监测技术联系起来。Construction of mechanically robust and fire safe thermoplastic polyurethane-based nanocomposites for electromagnetic interference shieldingLiu Miao, Wu Shijie, Huang Ruizhe, Shi Yongqian, Wang Hengrui, Feng Yuezhan, Tang Longcheng, Gao Jiefeng, Song Pingan, Lai Yuekundoi:10.1016/j.compositesa.2023.107818构建机械坚固、防火安全的热塑性聚氨酯基纳米复合材料,用于电磁干扰屏蔽Developing mechanically strong TPU-based nanocomposites with integrated fire resistance, smoke suppression and electromagnetic interference (EMI) shielding performances is a great challenge. Herein, we designed a tough and fire safe thermoplastic polyurethane/silicon wrapped ammonium polyphosphate polyphosphazene functionalized titanium carbide/carbon fiber fabric (TPU/SiAPZ@M/CF) nanocomposite with EMI shielding properties. The as-prepared TPU/SiAPZ@M nanocomposites showed excellent fire safety. For example, the peak of heat release rate, total heat release and total smoke release of TPU/SiAPZ@M-4.0 were significantly decreased by 77.9%, 46.7% and 51.6%, respectively, compared to those of pure TPU. Additionally, the tensile strength of TPU/SiAPZ@M-4.0/CF reached 55.1 MPa. Furthermore, this composite demonstrated acceptable EMI shielding performance, with an EMI shielding effectiveness of 27.4 dB, surpassing the commercial demand of 20 dB. Therefore, the combination of superior fire safety, high mechanical strength and excellent EMI shielding performances makes the hierarchical TPU/SiAPZ@M/CF nanocomposites promising applications in various fields.开发机械强度高且兼具防火、抑烟和电磁干扰(EMI)屏蔽性能的热塑性聚氨酯基纳米复合材料是一项巨大的挑战。在此,我们设计了一种具有电磁干扰屏蔽性能的坚韧且防火安全的热塑性聚氨酯/硅包裹聚磷酸铵聚磷氮功能化碳化钛/碳纤维织物(TPU/SiAPZ@M/CF)纳米复合材料。制备的 TPU/SiAPZ@M 纳米复合材料具有优异的防火安全性。例如,与纯热塑性聚氨酯相比,TPU/SiAPZ@M-4.0,热释放率峰值、总热释放量和总烟释放量分别显著降低了 77.9%、46.7% 和 51.6%。此外,TPU/SiAPZ@M-4.0/CF 的拉伸强度达到了 55.1 兆帕。此外,这种复合材料还具有可接受的 EMI 屏蔽性能,EMI 屏蔽效果达到 27.4 dB,超过了 20 dB 的商业要求。因此,该分层热塑性聚氨酯/SiAPZ@M/CF 纳米复合材料兼具卓越的防火安全性、高机械强度和出色的电磁干扰屏蔽性能,在各个领域都具有广阔的应用前景。Composites Part B: EngineeringConstructing a highly vertically aligned network of h-BN/CF in silicone rubber composites: Achieving superior through-plane thermal conductivity and electrical insulationJi Yuan, Han Shida, Zhang Qi, Wu Hong, Guo Shaoyun, Zhang Fengshun, Qiu Jianhuidoi:10.1016/j.compositesb.2023.111024在硅橡胶复合材料中构建高度垂直排列的 h-BN/CF 网络:实现优异的通面导热性和电绝缘性Polymer composites with both high through-plane thermal conductivity (TC) and electrical insulation are desperately needed for the efficient thermal management of modern electronic devices. Herein, a highly vertically aligned network of hexagonal boron (h-BN) nitride/carbon fiber (CF) was constructed in silicone rubber composites via the combination of multistage stretching extrusion, layer-by-layer stacking and hot-pressing procedures. The composites exhibited superior through-plane TC and electrical insulation, simultaneously. The through-plane TC of the composites reached 9.5 W/(m·K) when the content of h-BN and CF was 120 phr and 5 phr, respectively. Meanwhile, the volume resistivity and breakdown voltage of the composites were 1.89 × 1013 Ω·cm and 7.7 KV/mm, respectively, since the low content of CF was insufficient to form electrically conductive pathways. Furthermore, both simulation and experimental results indicated that the composites show outstanding heat dissipation performance. The composites with such hybrid networks are very promising for efficient heat dissipation in high-performance electronic devices.现代电子设备的高效热管理迫切需要同时具有高平面导热率(TC)和电绝缘性的聚合物复合材料。在本文中,通过多级拉伸挤出、逐层堆叠和热压程序的组合,在硅橡胶复合材料中构建了高度垂直排列的六方氮化硼/碳纤维(CF)网络。复合材料同时表现出优异的通面热导率和电绝缘性。当 h-BN 和 CF 的含量分别为 120 phr 和 5 phr 时,复合材料的通面 TC 达到 9.5 W/(m-K)。同时,由于低含量的 CF 不足以形成导电通路,复合材料的体积电阻率和击穿电压分别为 1.89 × 1013 Ω-cm 和 7.7 KV/mm。此外,模拟和实验结果表明,复合材料具有出色的散热性能。具有这种混合网络的复合材料很有希望在高性能电子设备中实现高效散热。Composites Science and TechnologyCarbon fiber reinforced polyethylene composite adhesive at elevated temperaturesFang Weiqing, Cheng Yu Hui, Pearson Adam, Duncan Mark, Runka Joel, Hammami Ahmed, Naguib Hani E.doi:10.1016/j.compscitech.2023.110269高温下的碳纤维增强聚乙烯复合粘合剂The development of multi-layer-multi-material thermoplastic structures necessitates the bonding of dissimilar materials with varying mechanical, chemical, barrier, and thermal properties. Thermoplastic adhesives, such as maleic anhydride grafted polyethylene (PE-MAH), are advantageous over thermoset adhesives given their similar manufacturability, and numerous benefits as sustainable materials in compliance with strict environmental regulation in construction, automotive, and energy industries. A key drawback is that PE-MAH demonstrates weak adhesive properties at elevated temperatures. In this study, the adhesion strength of carbon fiber (CF) reinforced PE-MAH at elevated temperatures were evaluated using a novel method of T-peel test under a controlled environment. Significant improvements of 71% and 295% increase in peel strength at 90 °C and 110 °C, respectively, were achieved with CF reinforcement over neat PE-MAH. The improving mechanisms were discussed on both macro-level, i.e., enhanced peel zone and eliminating crazing, and micro-level, i.e., transferred stress and dispersed energy into micro peel zones. This study demonstrates the efficacy of tailoring the adhesion strength of thermoplastic composite adhesive for significantly improved performance at elevated temperatures.开发多层多材料热塑性结构需要粘合具有不同机械、化学、阻隔和热性能的异种材料。与热固性粘合剂相比,马来酸酐接枝聚乙烯(PE-MAH)等热塑性粘合剂具有相似的可制造性,以及作为可持续材料符合建筑、汽车和能源行业严格的环境法规等诸多优点。其主要缺点是 PE-MAH 在高温下的粘合性能较弱。本研究在受控环境下采用一种新的 T 型剥离试验方法,评估了碳纤维(CF)增强聚乙烯-MAH 在高温下的粘合强度。与纯 PE-MAH 相比,CF 增强材料在 90 °C 和 110 °C 下的剥离强度分别提高了 71% 和 295%。研究从宏观层面(即增强剥离区和消除裂纹)和微观层面(即将应力和能量分散到微剥离区)讨论了改善机制。这项研究表明,定制热塑性复合材料粘合剂的粘合强度可显著改善高温下的性能。Deep-learning image enhancement and fibre segmentation from time-resolved computed tomography of fibre-reinforced compositesGuo Rui, Stubbe Johannes, Zhang Yuhe, Schlepütz Christian Matthias, Gomez Camilo Rojas, Mehdikhani Mahoor, Breite Christian, Swolfs Yentl, Villanueva-Perez Pablodoi:10.1016/j.compscitech.2023.110278深度学习图像增强和纤维增强复合材料时间分辨计算机断层扫描中的纤维分割Monitoring the microstructure and damage development of fibre-reinforced composites during loading is crucial to understanding their mechanical properties. Time-resolved X-ray computed tomography enables such an in-situ, non-destructive study. However, the photon flux and fibre-matrix contrast limit its achievable spatial and temporal resolution. In this paper, we push the limits of temporal and spatial resolution for the microstructural analysis of unidirectional continuous carbon fibre-reinforced epoxy composites by establishing a new pipeline based on CycleGAN for unsupervised super-resolution and denoising and U-Net-id for individual fibre segmentation. After illustrating the benefits of a 3D CycleGAN over a 2D one, we show that data enhanced by this pipeline can yield similar segmentation quality to that of a slow-acquisition, high-quality scan that took up to 200 times longer to acquire. This pipeline, therefore, enables more robust data extraction from fast time-resolved X-ray tomography, removing a critical stumbling block for this technique.在加载过程中监测纤维增强复合材料的微观结构和损伤发展对了解其机械性能至关重要。时间分辨 X 射线计算机断层扫描技术实现了这种现场非破坏性研究。然而,光子通量和纤维基质对比度限制了其可实现的空间和时间分辨率。在本文中,我们基于 CycleGAN(用于无监督超分辨率和去噪)和 U-Net-id (用于单个纤维分割)建立了一个新的管道,从而突破了单向连续碳纤维增强环氧复合材料微观结构分析的时空分辨率极限。在说明了三维 CycleGAN 相对于二维 CycleGAN 的优势之后,我们表明,通过该管道增强的数据可获得与慢速采集高质量扫描相似的分割质量,而慢速采集高质量扫描所需的时间是二维 CycleGAN 的 200 倍。因此,该流水线能从快速时间分辨 X 射线断层扫描中提取更可靠的数据,消除了这项技术的关键绊脚石。来源:复合材料力学仿真Composites FEM

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