今日更新:Composites Part A: Applied Science and Manufacturing 1 篇,Composites Part B: Engineering 4 篇,Composites Science and Technology 1 篇
Vibroscope method for determination of cross-sectional area of glass and carbon fibres– Theory and further development
Bo Madsen, Jan Høgsberg, Hans Lilholt
doi:10.1016/j.compositesa.2024.108446
玻璃纤维和碳纤维横截面积测定用振动镜方法。理论和进一步发展
Accurate determination of cross-sectional area of glass and carbon fibres by the vibroscope method is examined. Complete derivations of the central frequency solutions are presented, to make these derivations accessible in modern scientific literature. The effect of non-zero bending stiffness is included. The influence of shape of fibre cross-sectional area is analysed. Only small deviations in cross-sectional areas are found due to fibre shape, allowing for the use of the vibroscope method for fibres with non-circular cross-sectional areas. Two correction factors are introduced for the effect of volume change and area change of a tensioned fibre, allowing determination of the cross-sectional area of the non-tensioned fibre. A model plot of the vibroscope equation is presented, showing the numerical effect of the corrections on the fibre cross-sectional area depending on the applied tension force. The relations shown by the model plot have implications for the experimental settings of the vibroscope method.
研究了用振镜法精确测定玻璃纤维和碳纤维的横截面积。给出了中心频率解的完整推导,使这些推导在现代科学文献中易于理解。考虑了非零弯曲刚度的影响。分析了纤维截面面积形状的影响。由于纤维形状的原因,截面积只有很小的偏差,允许对非圆形截面积的纤维使用测振仪方法。引入了两个校正因子对拉伸纤维的体积变化和面积变化的影响,从而可以确定未拉伸纤维的横截面积。给出了测振器方程的模型图,显示了根据施加的张力,修正对纤维横截面积的数值影响。模型图所示的关系对测振仪方法的实验设置具有启示意义。
Enhancing toughness in cement-based composites: unraveling the composite effect mechanisms of polymers and fibers through physic testing and molecular dynamics simulations
Shi-Wei Zhang, Ru Wang, Jiao-Long Zhang, Yong Yuan
doi:10.1016/j.compositesb.2024.111827
增强水泥基复合材料的韧性:通过物理测试和分子动力学模拟揭示聚合物和纤维的复合效应机制
To reveal the toughening mechanism of polymers and fibers in composite applications, a combination of physical tests (uniaxial compression, flexural fracture, single fiber pull-out, scanning electron microscopy, and X-ray diffraction (XRD)) and molecular dynamics simulations have been carried out. Three polymers, i.e. ethylene-vinyl acetate copolymer (EVA), styrene-acrylate copolymer (SAE), and styrene-butadiene copolymer (SB), and two fibers, i.e. polypropylene fiber (PP) and polyvinyl alcohol fiber (PVA) are considered. Their composite effect mechanisms are explained in the viewpoint of three scales. At the macro-scale, the pull-out tests of single fiber show that the polymer increased the equivalent bond strength between the fiber and the mortar matrix. At micro-scale, it was observed from the SEM experiments that the fiber and polymer film inhibited the crack extension at different scales, besides the polymer could absorb on the fiber surface to improve the interfacial transition zone (ITZ) density around the fiber and increase the roughness of the fiber surface. At nano-scale, MD simulations demonstrate that three polymers facilitated the bond strength between PP fiber and C-S-H at the nano-scale, mainly because of the formation of Ca-O coordination bond and H-bonds between the polymers and C-S-H, and the presence of van der Waals forces between the polymers and PP fiber. However, SAE facilitated the bonding between the PVA fibers and the C-S-H, which originated from the coordination bonds formed between Ca ions on the surface of SAE and O atoms in PVA. In addition, the large number of H-bonds formed between SAE and PVA.
为了揭示聚合物和纤维在复合材料应用中的增韧机理,进行了物理测试(单轴压缩、弯曲断裂、单纤维拉出、扫描电子显微镜和x射线衍射(XRD))和分子动力学模拟。考虑了三种聚合物,即乙烯-醋酸乙烯共聚物(EVA)、苯乙烯-丙烯酸酯共聚物(SAE)和苯乙烯-丁二烯共聚物(SB)和两种纤维,即聚丙烯纤维(PP)和聚乙烯醇纤维(PVA)。从三个尺度的角度解释了它们的复合效应机制。在宏观尺度上,单纤维的拉拔试验表明,聚合物提高了纤维与砂浆基体之间的等效粘结强度。在微观尺度上,SEM实验观察到,纤维和聚合物膜在不同尺度上抑制了裂纹的扩展,聚合物在纤维表面的吸附作用提高了纤维周围界面过渡区(ITZ)密度,增加了纤维表面的粗糙度。在纳米尺度上,MD模拟表明,三种聚合物在纳米尺度上促进了PP纤维与C-S-H之间的键合强度,主要是由于聚合物与C-S-H之间形成了Ca-O配位键和h键,以及聚合物与PP纤维之间存在范德华力。然而,SAE促进了PVA纤维与C-S-H之间的键合,这源于SAE表面的Ca离子与PVA中的O原子之间形成的配位键。此外,SAE与PVA之间形成了大量的氢键。
In-situ formed silicon oxycarbide nanowires into porous SiC(rGO) PDCs enable balanced enhancement of robustness and thermal management
Wenyan Huang, Jiahao Liang, Kaiqi Chen, Ying Yu, Yeqi Zhu, Junhui Li, Cheng Pan, Yipeng Guo, Siqi Lan, Rongqian Yao
doi:10.1016/j.compositesb.2024.111828
原位形成的碳化硅纳米线可用于多孔碳化硅(rGO) pdc,可平衡增强稳健性和热管理
With ongoing development of rocket combustion and hypersonic vehicles, urgent needs are created on thermal structures, protection and thermal insulating materials, particularly balanced enhancement of mechanical and antioxidant properties. Herein, we propose a design strategy to construct continuous in-situ formed SiOC nanowires (SiOCnws)-toughened self-healing SiOx coatings into porous SiC(rGO) PDCs. The key production technique is re-pyrolyzing coassembled flexible precursors/SiC(rGO)p/graphite blends, followed by decarbonization and silica sol impregnation-sintering (SIS) process. Well-distributed hierarchical pores are built to heighten thermal insulation properties by the integrated decarburization of graphite coupled with free carbon. High-yield SiOCnws, with high surface activity, are first cultivated via graphite-assisted vapor-solid (VS) mechanism without transition metal catalysts. They interconnect to form intricate 3D meshwork by graphite-assisted melt-spinning and have good compatibility with ceramic matrix and SiOx coatings by carbothermal reaction. Hierarchically porous SiOCnws/SiC(rGO)40% PDCs after once SIS exhibit favorable thermal conductivity of 0.27 W·m-1·K-1 and exceptional high robustness (compressive strength: 39.02 MPa, hardness: 10.27 GPa). Such composites display low reflection loss of -48.14 dB at 11.22 GHz and even good structural stability at about 1300 °C as burned by a butane blowtorch for 3600 s, shedding light on competitive components for uses in thermal protection fields.
随着火箭燃烧和高超音速飞行器的不断发展,对热结构、保护和隔热材料提出了迫切的需求,尤其是在提高机械性能和抗氧化性能方面。在此,我们提出了一种在多孔 SiC(rGO)PDC 中构建连续原位成型 SiOC 纳米线(SiOCnws)-增韧自修复 SiOx 涂层的设计策略。关键的生产技术是重新热解共组装柔性前驱体/SiC(rGO)p/石墨混合物,然后进行脱碳和硅溶胶浸渍-烧结(SIS)工艺。通过对石墨和游离碳进行综合脱碳,形成了分布均匀的分层孔隙,从而提高了隔热性能。首先在不使用过渡金属催化剂的情况下,通过石墨辅助气固(VS)机制培养出具有高表面活性的高产 SiOCnws。它们通过石墨辅助熔融纺丝相互连接形成复杂的三维网状结构,并通过碳热反应与陶瓷基体和氧化硅涂层具有良好的兼容性。经过一次 SIS 后的分层多孔 SiOCnws/SiC(rGO)40%PDC 具有 0.27 W-m-1-K-1 的良好热导率和超高的坚固性(抗压强度:39.02 MPa,硬度:10.27 GPa)。这种复合材料在 11.22 GHz 频率下的反射损耗低至 -48.14 dB,甚至在丁烷喷灯灼烧约 1300 °C 3600 秒后仍具有良好的结构稳定性,为热保护领域提供了具有竞争力的元件。
Electrical resistance based residual strength prediction method for SiC/SiC mini-composites after stress-free oxidation
Beichen Xue, Guoqiang Yu, Chuyang Xie, Wenbing Ma, Jiaming Li, Xiguang Gao, Fang Wang, Yingdong Song
doi:10.1016/j.compositesb.2024.111832
基于电阻的SiC/SiC微复合材料无应力氧化残余强度预测方法
A stress-free oxidation model considering the microstructural characteristics of SiC/SiC mini-composites was proposed based on the electrical resistance change before and after oxidation. The relationship between the electrical resistance and the thickness of the internal fiber oxide layer was established. The stress-free oxidation tests were carried out at different temperatures for different oxidation times. The results of the oxide layer thickness calculated by the model agree well with those of the SEM observation. Based on the microstructure of tensile fracture after oxidation, the residual strength model of SiC/SiC mini-composites was proposed. The residual strength of the specimens after stress-free oxidation was calculated based on the oxide layer thickness obtained from the model. The error between the calculated and experimental results is within 14.48%.
基于氧化前后的电阻变化,提出了一种考虑SiC/SiC微型复合材料微观结构特征的无应力氧化模型。建立了电阻与内部氧化纤维层厚度之间的关系。在不同温度、不同氧化时间下进行了无应力氧化试验。模型计算的氧化层厚度与SEM观测结果吻合较好。基于氧化后拉伸断裂的微观组织,提出了SiC/SiC微型复合材料的残余强度模型。根据模型得到的氧化层厚度计算试样无应力氧化后的残余强度。计算结果与实验结果的误差在14.48%以内。
Hierarchical microstructure design of multifunctional soft collagen-incorporated 3D hard polyetherketoneketone scaffolds for augmented bone regeneration
Huanhuan Liu, Xiaoyin Liu, Taiqing Liu, Sihan Rao, ManLin Sun, YuSen Shui, Tian Luo, Yuwei Zhao, Haiyang Yu
doi:10.1016/j.compositesb.2024.111833
多功能软胶原复合三维硬聚醚酮增强骨再生支架的分层结构设计
Implant-associated infections and insufficient osseointegration are still great challenges in clinical load-bearing applications. Exploiting the antibacterial effects and immunomodulatory properties of biomaterials has garnered substantial attention. Inspired by structural and functional cues in bone regeneration, a universal approach was proposed in which a hydroxyapatite (HAp) coating was built on 3D printed polyetherketoneketone (PEKK) scaffold, and a bioactive component-loaded soft mineralized collagen hydrogel was incorporated into 3D hard PEKK scaffold. While the PEKK scaffold exhibited exceptional mechanical performance, in vitro and in vivo data confirmed that exosomes derived from rat bone marrow mesenchyme stem cells (rBMSCs) loaded on collagen hydrogel facilitate efficient osteoimmunomodulation of the PEKK-based scaffold (denoted as the PEKK-HAp-Col/Exo scaffold). Additionally, vancomycin-loaded nanoparticles cross-linked with collagen hydrogel endowed the PEKK-based scaffold (denoted as the PEKK-HAp-Col/Van scaffold) with enhanced antibacterial effects. Overall, this study not only sheds light on the significance of exosomes in the osteoimmunomodulation of an implant but also presents a universal material–structure–function integrated strategy to fabricate multifunctional scaffolds with a soft-hard hybrid structure for clinical large-scale bone defect repair.
种植体相关感染和骨整合不足仍然是临床承重应用的巨大挑战。利用生物材料的抗菌作用和免疫调节特性已经引起了人们的广泛关注。受骨再生的结构和功能线索的启发,提出了一种通用的方法,即在3D打印聚醚酮酮(PEKK)支架上构建羟基磷灰石(HAp)涂层,并将生物活性成分负载的软矿化胶原水凝胶结合到3D硬PEKK支架中。虽然PEKK支架表现出优异的机械性能,但体外和体内数据证实,胶原水凝胶负载的大鼠骨髓间充质干细胞(rBMSCs)衍生的外泌体促进了基于PEKK的支架(称为PEKK- hap - col /Exo支架)的有效骨免疫调节。此外,负载万古霉素的纳米颗粒与胶原水凝胶交联,使pekk支架(称为PEKK-HAp-Col/Van支架)具有增强的抗菌作用。总的来说,本研究不仅揭示了外泌体在种植体骨免疫调节中的重要性,而且提出了一种通用的材料-结构-功能集成策略,用于临床大规模骨缺损修复的软硬混合结构多功能支架。
Investigation of buckling instabilities in fiber-reinforced DEAs
Stefania Konstantinidi, Markus Koenigsdorff, Thomas Martinez, Amine Benouhiba, Johannes Mersch, Yoan Civet, Gerald Gerlach, Yves Perriard
doi:10.1016/j.compscitech.2024.110849
纤维增强dea的屈曲不稳定性研究
Artificial muscles, designed to replicate the movements of natural biological muscles, hold significant promise in the fields of robotics and prosthetics. Recent advancements have led to the development of fiber-reinforced actuators, drawing inspiration from biological tissues. Dielectric elastomer actuators (DEAs) are a type of electroactive artificial muscle. It is possible to enhance the uni-axial deformation of DEAs by constraining and applying pre-stretch on the actuator membrane. This can be achieved through uni-directional fibers bonded to the DEA that lead to transversely isotropic properties. However, combining membrane pre-stretch and fiber reinforcement may lead to instabilities such as fiber buckling due to the compressive load of the pre-stretched membrane or due to wrinkling during actuation. Understanding these instabilities is crucial as they can significantly impact the performance. A novel model taking into consideration these instabilities is established and experimentally validated. By calculating the force in the fiber direction, the buckling profile such as the wavelength and amplitude can be predicted. The validation of the model presented along with an extensive experimental investigation allow for a comprehensive analysis to explore the impact of fiber buckling on the performance and the force of uni-axial DEAs.
人造肌肉是为了复 制自然生物肌肉的运动而设计的,在机器人和假肢领域有着重要的前景。最近的进步导致了纤维增强致动器的发展,从生物组织中汲取灵感。介电弹性体致动器是一种电活性人造肌肉。在致动器薄膜上施加预拉伸和约束可以增强致动器的单轴变形。这可以通过与DEA结合的单向光纤实现,从而获得横向各向同性。然而,将膜预拉伸与纤维增强相结合可能会导致不稳定,如由于预拉伸膜的压缩载荷或由于驱动过程中的起皱而导致纤维屈曲。理解这些不稳定性至关重要,因为它们会显著影响性能。建立了考虑这些不稳定性的新模型,并进行了实验验证。通过计算光纤方向上的力,可以预测光纤的屈曲曲线,如波长和振幅。该模型的验证以及广泛的实验研究允许对纤维屈曲对单轴dea性能和力的影响进行全面分析。