今日更新：Composite Structures 1 篇，Composites Part A: Applied Science and Manufacturing 5 篇，Composites Science and Technology 1 篇Composite StructuresExperimental investigation on a FRCM bio-composite for sustainable retrofitting of masonry buildingsMarco Corradi, Stefano Agnetti, Chiara Quintaliani, Emanuela Speranzinidoi:10.1016/j.compstruct.2023.117753用于砌体建筑可持续改造的 FRCM 生物复合材料实验研究Strengthening masonry structures by using green and natural materials has received increasing attention. Natural fibers can be obtained from vegetables, animals or mineral sources and can be used to meet modern buildings safety standards and to reduce carbon dioxide emissions. This paper presents a novel method to strengthen masonry buildings through the application of a mortar coating reinforced with natural fibers made of a jute or a basalt grid. This class of materials is known as Fiber Reinforced Cementitious Matrix (FRCM). FRCM composites can produce an increment in the mechanical properties of the masonry members and contribute to the thermal-acoustic insultation of the building envelope. The mortar coating is made of a hydraulic lime: to increase thermal properties this was admixed with short spelt fibers. Both matrix (lime mortar) and fibrous material were initially mechanically and thermally characterized. Laboratory tests have been carried out to study the bond characteristics between the FRCM composite and brickwork masonry. It was found the low mechanical properties of jute fibers are aggravated by a low FRCM-to-masonry bonding, making difficult to use this material for structural retrofit. On opposite, basalt fibers exhibit high mechanical properties and their use in conservation is surely promising and interesting.使用绿色天然材料加固砌体结构已受到越来越多的关注。天然纤维可从蔬菜、动物或矿物中获取，可用于满足现代建筑安全标准和减少二氧化碳排放。本文介绍了一种新方法，通过使用黄麻或玄武岩网格天然纤维加固砂浆涂层来加固砌体建筑。这类材料被称为纤维增强水泥基质（FRCM）。纤维增强水泥基复合材料可提高砌体构件的机械性能，并有助于减轻建筑外墙的热声损伤。砂浆涂层由水力石灰制成：为了提高热性能，砂浆中加入了短纤维。基体（石灰砂浆）和纤维材料最初都具有机械和热特性。为了研究 FRCM 复合材料与砖砌体之间的粘结特性，还进行了实验室测试。结果发现，黄麻纤维的机械性能较低，而 FRCM 与砌体之间的粘结力较低，这使得这种材料难以用于结构改造。与此相反，玄武岩纤维则表现出较高的机械性能，将其用于保护工程无疑是很有前景和意义的。Composites Part A: Applied Science and ManufacturingDeconsolidation of carbon fiber-reinforced PEKK laminates: 3D real-time in situ observation with synchrotron X-ray microtomographyLuc Amedewovo, Laurent Orgéas, Basile de Parscau du Plessix, Nicolas Lefevre, Arthur Levy, Steven Le Corredoi:10.1016/j.compositesa.2023.107917碳纤维增强 PEKK 层压板的解固：利用同步辐射 X 射线显微层析技术进行三维实时原位观测Deconsolidation of carbon-fibre reinforced thermoplastic laminate occurs while (pre)heating the materials during their forming processes. Pores nucleate, grow and lead to degradations of mechanical properties. Here, a new experimental device was developed and installed inside a synchrotron beamline (dedicated to fast X-ray microtomography). Pore nucleation and growth was observed in 3D, real-time and in situ while heating Carbon/PEKK laminate samples. The time evolution of sample deconsolidation strain, porosity, as well as number, size and morphology of pores was assessed. Nucleation and growth is observed above the glass transition temperature and enhanced with initial moisture content. Drastic deconsolidation when approaching melting temperature is thought to be driven by internal stress in the laminate. The data provided may be used as input for modeling purposes or for validation of existing models.碳纤维增强热塑性塑料层压板在成型过程中进行（预）加热时会出现脱固现象。孔隙成核、生长并导致机械性能下降。在此，我们开发了一种新的实验装置，并将其安装在同步辐射光束线（专用于快速 X 射线显微层析成像）内。在加热碳/PEKK 层压板样品时，对孔隙成核和生长进行了三维、实时和原位观测。评估了样品脱固应变、孔隙率以及孔隙数量、大小和形态的时间演变。在玻璃转化温度以上观察到了成核和生长现象，并随着初始含水量的增加而增强。接近熔化温度时的急剧解固被认为是由层压板中的内应力驱动的。所提供的数据可用于建模或验证现有模型。Bioinspired Hybrid Helical Structure in Lobster Homarus Americanus: Enhancing Penetration Resistance and Protective PerformanceXiaofang Zhang, Yanan Yuandoi:10.1016/j.compositesa.2023.107927 龙虾中的生物启发混合螺旋结构：增强抗穿透性和保护性能The high impact and penetration resistance of the cuticle in the lobster Homarus americanus can be attributed to its unique twisted plywood structure. Hybridization of two helical structures was observed in the exoskeleton, with different pitch angles and ply thickness of the exocuticle and endocuticle within the exoskeleton. Given the survival challenges posed by the natural environment, it is worthwhile to study why it evolved into a hybrid helical rather than a uniform helical structure. In light of this, we have proposed an innovative bionic hybrid helical structure design strategy that goes beyond simply reducing the pitch angle. In this paper, we replicated complex biological microstructures by introducing two types of pitch angles and ply thicknesses for regional configurations. Quasi Static Indentation (QSI) full-penetration experiments were conducted. Experimental results revealed that the exocuticle with a large pitch angle and small ply thickness possesses a higher knee load under the penetration test, which provides a higher initial damage threshold. On the other hand, the endocuticle with a small pitch angle and large ply thickness induces higher damage dissipation, which provides superior protective performance. These research findings demonstrate that ply hybridization can be a promising method for microstructure design to improve the penetration resistance of thin laminates and serve as a reference for developing more refined gradient helical structure designs.美洲龙虾（Homarus americanus）的角质层具有很高的抗冲击和抗穿透性，这要归功于其独特的扭曲胶合板结构。在外骨骼中观察到两种螺旋结构的杂交，外骨骼中的外表皮层和内表皮层具有不同的节距角和层厚。鉴于自然环境带来的生存挑战，值得研究它为什么会进化成一种混合而不是均匀的螺旋结构。有鉴于此，我们提出了一种创新的仿生混合螺旋结构设计策略，而不仅仅是简单地减小螺距角。在本文中，我们通过引入两种间距角和层厚的区域配置，复 制了复杂的生物微结构。我们进行了准静态压痕（QSI）全穿透实验。实验结果表明，间距角大、层厚小的外茧在穿透试验中具有更高的膝部载荷，从而提供了更高的初始损伤阈值。另一方面，间距角小、层厚大的内层材料能产生更高的损伤耗散，从而提供更优越的保护性能。这些研究结果表明，层间杂化是一种很有前途的微结构设计方法，可提高薄层板的抗穿透性，并为开发更精细的梯度螺旋结构设计提供参考。Mixed Modes Crack Propagation of Orthogonal Woven-layer in Carbon/Aramid/Epoxy LaminatesYuan Fu, Wei Yan Lv, Wen Hai Sun, Li Min Xu, Hui Guodoi:10.1016/j.compositesa.2023.107929碳/芳纶/环氧层压板中正交编织层的混合模式裂纹扩展This work presents a combined formulation for the fracture model of carbon/aramid fiber reinforced plastic woven laminates (CARPWLs). The structural crack is implemented based on Extended Finite Element Method (XFEM) and Cohesive Zone Model (CZM) with a mixed-mode loading. This work considers four types of fracture mechanics CARPWLs testing samples, each composed of five woven layers with different stacking sequences. The loading device for mixed modes is achieved through a fixture with a secondary level rotating wheel configured with samples via bolting. Additionally, a new velocity control servo script for driving force is proposed to obtain R-curves during the fracture process of Type I, II and III. The energy release rate G for I/II/III mixed modes are also studied by experimental and numerical methods on account of fracture mechanics. The numerical verification performs highly accuracy to experiments, and it provides an efficiency approach for evaluating failure response of laminates.本研究提出了碳/芳纶纤维增强塑料编织层压板（CARPWLs）断裂模型的组合公式。结构裂纹是基于扩展有限元法（XFEM）和混合模式加载的内聚区模型（CZM）实现的。本研究考虑了四种类型的断裂力学 CARPWLs 测试样本，每种样本由五层编织层组成，每层编织层的堆叠顺序各不相同。混合模式加载装置是通过一个带有二级旋转轮的夹具实现的，该夹具通过螺栓与样品连接。此外，还提出了一种新的驱动力速度控制伺服脚本，以获得 I、II 和 III 型断裂过程中的 R 曲线。根据断裂力学，还通过实验和数值方法研究了 I/II/III 混合模式的能量释放率 G。数值验证结果与实验结果具有很高的精确度，为评估层压板的破坏响应提供了一种有效的方法。Pre-compositing polyetherketoneketone with short-cut carbon fibers into advanced powder materials toward composites with fully-adhered interfacesXin Wang, Yiting Qu, Junlei Bai, Fujun Xu, Bin Ding, Xiaohua Zhangdoi:10.1016/j.compositesa.2023.107930将聚醚醚酮与短切碳纤维预复合到先进的粉末材料中，形成具有全粘合界面的复合材料It is challenging to realize intimate interface between reinforcement and matrix using powder materials, due to the high melting points and melt viscosities of thermoplastics like polyaryletherketones. Herein, a solution-based strategy is proposed to prepare pre-composition in powders, and using them, full and tight fiber–matrix bounding is formed in the final composites. Owing to the dissolubility of polyetherketoneketone (PEKK), short-cut carbon fibers (CFs) are uniformly introduced into the solution and fully covered by PEKK, i.e., the pre-composition. The composite powders lead to structural uniformity, full utilization of CF surfaces, and avoidance of CF aggregation. The hot-compressed beams exhibit remarkably enhanced tensile and flexural strengths (135.5 and 173.7 MPa), more than 30% and 60% higher than those of the pure PEKK. Meanwhile, they possess high tensile and flexural strains at break up to 5.5% and 11.4%, respectively, enhanced crystallinity up to 17.7%, and high thermal conductivity of 0.26–0.29 Wm−1 K−1. The pre-composition also exhibits other advantages, such as the higher powder flowability, reduced steps of high-temperature processing, and superior anti-abrasion ability and enhanced thermal stability of composite beams.由于聚芳醚酮等热塑性塑料的熔点和熔体粘度较高，使用粉末材料实现增强体与基体之间的紧密结合具有挑战性。本文提出了一种基于溶液的策略来制备粉末中的预复合材料，并利用它们在最终复合材料中形成完整而紧密的纤维-基体结合。由于聚醚醚酮酮（PEKK）的可溶性，短切碳纤维（CF）被均匀地引入溶液中，并被聚醚醚酮酮（PEKK）完全覆盖，即预合成。这种复合粉末具有结构均匀、充分利用碳纤维表面和避免碳纤维聚集的特点。热压梁的抗拉和抗弯强度（135.5 和 173.7 兆帕）显著提高，比纯 PEKK 高出 30% 和 60% 以上。同时，它们的拉伸和弯曲断裂应变分别高达 5.5% 和 11.4%，结晶度提高到 17.7%，导热系数高达 0.26-0.29 Wm-1 K-1。这种预复合材料还具有其他优点，如粉末流动性更高、减少了高温加工步骤、抗磨损能力更强以及增强了复合梁的热稳定性。High-performance chlorinated polyvinyl chloride/polyurea nanocomposite foam with excellent solvent resistance, flame-triggered shape memory effect and its upcyclingJiangan You, Ling Cai, Ronghua Yu, Haiping Xing, Jian Xue, Ying Li, Zhiwei Jiang, Dongmei Cui, Tao Tangdoi:10.1016/j.compositesa.2023.107931 高性能氯化聚氯乙烯/聚脲纳米复合泡沫，具有优异的耐溶剂性、火焰触发的形状记忆效果和可循环利用性Facing the global environmental pollution crisis related to waste plastics, the recyclable design of polymer materials and composites, especially large commodities, is the most effective and fundamental solution. Herein, an upcycling chlorinated polyvinyl chloride/polyurea (CPVC/PUA) nanocomposite foam was designed by means of the “plasticizing-foaming-reinforcing” (PFR) strategy combined with catalytic carbonization of CPVC/PUA foams. On one hand, the foam with ultra-high expansion ratio (62 times) can be facilely prepared in supercritical CO2 at lower temperature, benefited of the reactive plasticizing function of PUA monomer-polymeric methylene diphenyldiisocyanate (PMDI). On the other hand, the obtained foam is reinforced by PMDI crosslinking reaction to in situ form nano-PUA phase in the CPVC matrix and realizing robust and superior solvent resistance and flame-triggered shape memory effect. Moreover, the foam possesses remarkable ablation resistance, which is attributed to super carbonization capacity of CPVC catalyzed by PUA. This carbonization behavior endows the foam directly upcycle into functional carbon foam accompanied by the formation of HCl gas and functional aromatics. The obtained carbon foam shows attractive electromagnetic interference shielding performance, which also may be used as potential carbon source or catalyst of producing vinyl chloride monomer in the chlor-alkali industry, especially in China.面对与废塑料相关的全球环境污染危机，高分子材料和复合材料（尤其是大宗商品）的可回收设计是最有效、最根本的解决方案。本文采用 "塑化-发泡-增强"（PFR）策略，结合 CPVC/PUA 泡沫的催化碳化，设计了一种可循环利用的氯化聚氯乙烯/聚脲（CPVC/PUA）纳米复合泡沫。一方面，得益于 PUA 单体-聚亚甲基二苯基二异氰酸酯（PMDI）的反应增塑功能，可在超临界 CO2 中以较低温度轻松制备出具有超高膨胀比（62 倍）的泡沫。另一方面，所获得的泡沫通过 PMDI 交联反应在 CPVC 基体中原位形成纳米 PUA 相，从而增强了泡沫的强度和优异的耐溶剂性，并实现了火焰触发的形状记忆效果。此外，泡沫还具有显著的耐烧蚀性，这归功于 CPVC 在 PUA 催化下的超强碳化能力。这种碳化行为使泡沫在形成 HCl 气体和功能芳烃的同时，直接上升循环为功能碳泡沫。所获得的碳泡沫具有极佳的电磁干扰屏蔽性能，也可用作氯碱工业（尤其是中国）生产氯乙烯单体的潜在碳源或催化剂。Composites Science and TechnologyA multi-fidelity data-driven model for highly accurate and computationally efficient modeling of short fiber compositesHon Lam Cheung, Mohsen Mirkhalafdoi:10.1016/j.compscitech.2023.110359 用于短纤维复合材料高精度和高效计算建模的多保真度数据驱动模型To develop physics-based models and establish a structure–property relationship for short fiber composites, there are a wide range of micro-structural properties to be considered. To achieve a high accuracy, high-fidelity full-field simulations are required. These simulations are computationally very expensive, and any single analysis could potentially take days to finish. A solution for this issue is to develop surrogate models using artificial neural networks. However, generating a high-fidelity data set requires a huge amount of time. To solve this problem, we used transfer learning technique, a limited amount of high-fidelity full-field simulations, together with a previously developed recurrent neural network model trained on low-fidelity mean-field data. The new RNN model has a very high accuracy (in comparison with full-field simulations) and is remarkably efficient. This model can be used not only for highly efficient modeling purposes, but also for designing new short fiber composites.要为短纤维复合材料开发基于物理的模型并建立结构-性能关系，需要考虑广泛的微观结构特性。为了达到高精度，需要进行高保真全场模拟。这些模拟的计算成本非常昂贵，任何一项分析都可能需要数天才能完成。解决这一问题的办法是利用人工神经网络开发替代模型。然而，生成高保真数据集需要大量时间。为了解决这个问题，我们使用了迁移学习技术、有限的高保真全场模拟，以及之前开发的以低保真平均场数据为基础训练的递归神经网络模型。新的循环神经网络模型具有非常高的精度（与全场模拟相比）和显著的效率。该模型不仅可用于高效建模，还可用于设计新型短纤维复合材料。来源：复合材料力学仿真Composites FEM
