今日更新:Composite Structures 2 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 2 篇
Optimization of Friction Lap Joining Parameters and Exploration Connection Mechanism of CFRPA6/6061-T6 Aluminum Alloy Hybrid Structures
Li Yan, Bi Xiaoyang, Xu Mengjia, Xie Zhengchao, Wang Zhenmin
doi:10.1016/j.compstruct.2023.117566
CFRPA6/6061-T6 铝合金混合结构的摩擦搭接参数优化与连接机理探索
Carbon-fiber-reinforced thermoplastics (CFRTP) and lightweight-metal hybrid structures have been applied in the automotive and aerospace industries. Nonetheless, due to the enormous differences in physical and chemical properties of materials, the stability of the CFRTP and the lightweight-metal hybrid joint interface is challenging to ensure. In current work, the influence of welding parameters (rotational speed, welding speed, and plunge depth) on the stability of friction lap joining (FLJ) hybrid joints between carbon-fiber reinforced polyamide6 (CFRPA6) and 6061-T6 aluminum alloy (6061) was studied. The analysis of variance (ANOVA) showed that the rotational speed was the greatest factor affecting joint strength. By optimizing the welding parameters, a high-strength hybrid joint with a maximum tensile force of 2.5 kN was obtained. To further understand the mechanism of interface connection, experimental methods and density functional theory (DFT) calculations were systemically performed. The results show that the nitrogen and oxygen atoms in CFRPA6 will bond with aluminum on the 6061 surfaces to produce the interfacial Al-N and Al-O covalencies due to the p-orbital hybridization between bonding atoms.
碳纤维增强热塑性塑料(CFRTP)和轻质金属混合结构已被应用于汽车和航空航天工业。然而,由于材料的物理和化学性质存在巨大差异,要确保碳纤维增强热塑性塑料和轻质金属混合材料接头界面的稳定性具有挑战性。在当前工作中,研究了焊接参数(旋转速度、焊接速度和切入深度)对碳纤维增强聚酰胺 6(CFRPA6)和 6061-T6 铝合金(6061)之间摩擦搭接(FLJ)混合接头稳定性的影响。方差分析(ANOVA)表明,转速是影响接头强度的最大因素。通过优化焊接参数,获得了最大拉力为 2.5 kN 的高强度混合接头。为了进一步了解界面连接的机理,实验方法和密度泛函理论(DFT)计算被系统地应用。结果表明,CFRPA6 中的氮原子和氧原子会与 6061 表面的铝结合,由于结合原子之间的 p 轨道杂化作用,产生界面 Al-N 和 Al-O 共价。
High accuracy 3D printing of composite materials using CNT yarns
Sano Junro, Matsuzaki Ryosuke
doi:10.1016/j.compstruct.2023.117577
使用 CNT 纱线高精度 3D 打印复合材料
Generally, the 3D printing of continuous carbon fiber involves using filaments with a large diameter. Consequently, this has made it particularly challenging to achieve precise printing and intricate detailing, particularly in curved sections. Therefore, in this study, we aim to evaluate the formability of CNT (Carbon nanotube) yarn as an alternative filament and compare it with the formability achieved with conventional filaments. Printing a single-layer circle using CNT yarn revealed that using CNT yarn enabled printing of circles with a setting radius of 0.9 mm, thus demonstrating the feasibility of submillimeter-scale printing, which was not possible with conventional filaments. Additionally, the maximum gap in the print width (Δw) was reduced by approximately 73.7 % in circle printing and was reduced by approximately 69.5 % in bending printing, respectively. Thus, it can be asserted that the use of CNT yarns enables more precise printing of finer shapes.
一般来说,连续碳纤维的三维打印需要使用直径较大的细丝。因此,要实现精确打印和复杂的细节处理,尤其是弯曲部分的细节处理,就显得尤为困难。因此,在本研究中,我们旨在评估 CNT(碳纳米管)纱线作为替代长丝的成型性,并将其与传统长丝的成型性进行比较。使用碳纳米管纱线打印单层圆形的结果表明,使用碳纳米管纱线可以打印出设定半径为 0.9 毫米的圆形,从而证明了亚毫米级打印的可行性,而这是传统丝线无法实现的。此外,打印宽度的最大差距(Δw)在圆形印刷中减少了约 73.7%,在弯曲印刷中减少了约 69.5%。因此可以断言,使用 CNT 纱线可以更精确地印刷出更精细的形状。
In situ boron-doped flower-like NiS2@NC with sulfur vacancy composites for high energy density asymmetric supercapacitors
Song Fangxiang, Yang Gang, Pan Ling, Chen Qianlin
doi:10.1016/j.compositesb.2023.111025
用于高能量密度不对称超级电容器的原位掺硼花状 NiS2@NC 硫空位复合材料
In response to the challenges posed by the intricate synthesis process and low conductivity of nickel-based hydroxides, a straightforward and environmentally friendly method was proposed for the preparation of B-doped α-Ni(OH)2(α-Ni(OH)2–B). Additionally, B-doped NiS2@NC composites with sulfur vacancies (B-Sv-NiS2@NC) were prepared through nitrogen-doped carbon coating and vulcanization process. The resulting B-Sv-NiS2@NC electrode materials exhibited a specific capacity of 659C g−1 under a high specific potential (ΔV) of 1.0 V vs. Hg/HgO. Asymmetric supercapacitors α-Ni(OH)2–B//YP-80 and B-Sv-NiS2@NC//YP-80 were constructed and obtain 128.45C g−1 and 199.5C g−1 specific capacity at 0.5 A g−1 and 0.7 A g−1, respectively. Meanwhile, the α-Ni(OH)2–B//YP-80 and B-Sv-NiS2@NC//YP-80 demonstrated energy densities of 30.33 Wh kg−1 and 47.1 Wh kg−1 under 1.7 V working voltage window, respectively. The cycle capacity retention rates of the two devices reached 96% (8000 cycles) and 116% (10,000 cycles). The surface pseudocapacitance mechanism and charge transfer mechanism of α-Ni(OH)2–B and B-Sv-NiS2@NC were revealed by first principles DFT. The findings of the study demonstrate that the introduction of B doping significantly augmented the adsorption of OH− and facilitated the surface redox reaction. The OH− adsorption energy increased to −1.43 eV upon the incorporation of B and Sv, indicating that the adsorption of OH− on the B-Sv-NiS2@NC surface was more stable, thereby promoting a swift electrochemical reaction. The improved electronic structure of the material, coupled with the increased number of electrochemical active sites, resulted in enhanced OH− adsorption, accelerated redox reaction, and improved charge transfer, ultimately leading to improved electrochemical performance.
针对镍基氢氧化物复杂的合成工艺和低导电性所带来的挑战,提出了一种简单、环保的方法来制备掺B的α-Ni(OH)2(α-Ni(OH)2-B)。此外,还通过掺氮碳涂层和硫化工艺制备了含硫空位的掺B NiS2@NC复合材料(B-Sv-NiS2@NC)。所制备的 B-Sv-NiS2@NC 电极材料在 1.0 V 对 Hg/HgO 的高比电位(ΔV)条件下显示出 659C g-1 的比容量。构建的不对称超级电容器α-Ni(OH)2-B//YP-80 和 B-Sv-NiS2@NC//YP-80 在 0.5 A g-1 和 0.7 A g-1 下分别获得 128.45C g-1 和 199.5C g-1 的比容量。同时,在 1.7 V 工作电压窗口下,α-Ni(OH)2-B//YP-80 和 B-Sv-NiS2@NC//YP-80 的能量密度分别为 30.33 Wh kg-1 和 47.1 Wh kg-1。两种器件的循环容量保持率分别达到 96%(8000 次)和 116%(10000 次)。第一性原理 DFT 揭示了 α-Ni(OH)2-B 和 B-Sv-NiS2@NC 的表面伪电容机制和电荷转移机制。研究结果表明,掺杂 B 显著增强了对 OH- 的吸附,促进了表面氧化还原反应。掺入 B 和 Sv 后,OH- 的吸附能增加到-1.43 eV,表明 B-Sv-NiS2@NC 表面对 OH- 的吸附更加稳定,从而促进了电化学反应的迅速进行。该材料电子结构的改善以及电化学活性位点数量的增加增强了对 OH- 的吸附,加速了氧化还原反应,改善了电荷转移,最终提高了电化学性能。
A distortion-map-based method for morphology generation in multi-phase materials - Application to wood
Chen Bin, Montanari Céline, Popov Sergei, Berglund Lars A.
doi:10.1016/j.compscitech.2023.110262
基于变形图的多相材料形态生成方法 - 在木材中的应用
Increased use of multi-phase, wood-based biocomposites may contribute to sustainable development. The porous microstructure offers unique possibilities for modification, but global properties are often predicted based on simplified unit cells and homogenization. For materials design, simulations based on complex 3D microstructures with statistical variability are alternatives to better understanding physical properties. Parametric models are developed in a distortion-map-based method to represent 3D wood microstructures. Basic structures of uniform tubular cells and other features are generated followed by distortion mapping. These maps are highly adaptable and can generate realistic features and variability. Fibers, vessels, and ray cells are realistically distributed. The models are realistic, versatile, and scalable, as well as can be used to simulate the mechanical, optical, and hydrodynamic properties of complex composites. The model is promising for generating large sets of data to train deep learning networks for multi-physics research.
增加多相木基生物复合材料的使用可促进可持续发展。多孔微结构为改性提供了独特的可能性,但全局特性通常是基于简化的单元格和均质化来预测的。对于材料设计而言,基于具有统计变异性的复杂三维微结构的模拟是更好地理解物理性质的替代方法。我们采用基于变形图的方法开发了参数模型,以表示三维木材微结构。先生成由均匀管状单元和其他特征组成的基本结构,然后绘制变形图。这些映射具有很强的适应性,可以生成逼真的特征和变化。纤维、血管和射线细胞分布逼真。这些模型逼真、通用、可扩展,可用于模拟复杂复合材料的机械、光学和流体力学特性。该模型有望生成大量数据集,用于训练多物理场研究的深度学习网络。
Highly efficient electromagnetic wave absorption nanocomposite foam fabricated via low-dimension cell wall stretching and designed via nanoparticle Monte Carlo modeling
Ma Haoyu, Gong Pengjian, Li Guangxian, Park Chul B.
doi:10.1016/j.compscitech.2023.110274
通过低维度细胞壁拉伸制作高效电磁波吸收纳米复合泡沫,并通过纳米粒子蒙特卡洛建模进行设计
For nanocomposites, conductive nanofiller physical distance in polymer matrix plays the dominant role in their electrical conductivity, dielectric property, and electromagnetic wave (EMW) absorption properties. In this work, supercritical fluid-assisted cell wall stretching was used to regulate the physical distance among carbon nanofillers in cell walls. It is found that the effect of increased cell wall stretching ratio could be used to optimize the average shortest multi-wall carbon nanotubes (MWCNT) distance (to be around 6 nm–13 nm), and hence significantly increase electron tunneling loss and simultaneously induce high polarization loss. Monte Carlo simulation enables precise control of the physical distance among carbon nanofillers in the stretched cell walls. Guided by the above theoretical design strategy, EMW absorbing MWCNT/poly(vinylidene fluoride) (PVDF) nanocomposite foam with a −41.53 dB absorption performance cover all Ku-band (12.4–18 GHz) was successfully fabricated using the tailored cell wall stretching method. Followed by a simple combination of the above foam with an unfoamed nanocomposite film containing hybrid nanofillers of MWCNT/GNP, an extremely high EMI shielding material with superior absorption performance of an average absorption-to-reflection (A/R) coefficient ratio of 15.9 and a low refection bandwidth of 4.75 GHz (A/R ratio >10) was experimentally obtained.
对于纳米复合材料而言,导电纳米填料在聚合物基体中的物理距离对其导电性、介电性能和电磁波(EMW)吸收性能起着主导作用。本研究利用超临界流体辅助细胞壁拉伸来调节碳纳米填料在细胞壁中的物理距离。研究发现,细胞壁拉伸比的增加可用于优化多壁碳纳米管(MWCNT)的平均最短间距(约为 6 nm-13 nm),从而显著增加电子隧道损耗,并同时引起高极化损耗。蒙特卡罗模拟可以精确控制拉伸细胞壁中碳纳米填料之间的物理距离。在上述理论设计策略的指导下,利用量身定制的细胞壁拉伸方法成功制造出了电磁波吸收MWCNT/聚偏二氟乙烯(PVDF)纳米复合泡沫,其-41.53 dB的吸收性能覆盖了所有Ku波段(12.4-18 GHz)。随后,将上述泡沫与含有 MWCNT/GNP 混合纳米填料的未发泡纳米复合膜进行简单组合,实验得到了一种极高的 EMI 屏蔽材料,其平均吸收反射系数比为 15.9,低反射带宽为 4.75 GHz(A/R 比大于 10),具有极佳的吸收性能。