今日更新:Composite Structures 2 篇,Composites Part A: Applied Science and Manufacturing 2 篇,Composites Part B: Engineering 1 篇
A comparative study of tensile fatigue life in various flexible-oriented three-dimensional woven process structures based on finite element models
Chenchen Tan, Hao Huang, Zheng Sun, Zhongde Shan, Zitong Guo, Kehong Guo, Jinshuai Bian, Weihao Wang
doi:10.1016/j.compstruct.2024.118680
基于有限元模型的不同柔性三维编织工艺结构拉伸疲劳寿命对比研究
To achieve a comparative study of tensile fatigue life in various three-dimensional (3D) structures, 3D orthogonal woven composite (3DOWC), off-axis 3D orthogonal woven composite (OA-3DOWC) and multiaxial 3D woven composite (M3DWC), were designed and manufactured. Tensile and fatigue tests were performed, and microcomputed tomography (Micro-CT) was utilized to observe the mesoscale structural characteristics and the fatigue fracture morphology. Finite element models were established based on the observation. Then a modified power-law fatigue damage model was used for reduction of stiffness and strength during fatigue loading process, and a normalized life model was used to predict the fatigue life at different stress levels. Comparisons were conducted with existing models to analyze their predictive accuracy. Results showed that the tensile strength of M3DWC decreased by 54.6 % compared to 3DOWC, while its fatigue performance of M3DWC was significantly improved. Additionally, OA-3DOWC had the worst tensile strength but slightly improved fatigue performance compared to 3DOWC. And for the maximum error between the prediction and experimental results for the fatigue life is 11.16 %. For the fatigue life at the same stress level, M3DWC > OA-3DOWC > 3DOWC, due to the complex crack propagation paths in the staggered fiber arrangement.
为实现不同三维结构拉伸疲劳寿命的对比研究,设计制造了三维正交编织复合材料(3DOWC)、离轴三维正交编织复合材料(OA-3DOWC)和多轴三维编织复合材料(M3DWC)。进行了拉伸和疲劳试验,并利用微计算机断层扫描(Micro-CT)观察了中尺度结构特征和疲劳断口形貌。在此基础上建立了有限元模型。然后采用修正幂律疲劳损伤模型对疲劳加载过程中的刚度和强度进行降低,并采用归一化寿命模型对不同应力水平下的疲劳寿命进行预测。与现有模型进行比较,分析其预测精度。结果表明,与3DOWC相比,M3DWC的抗拉强度降低了54.6% %,但其疲劳性能得到了显著提高。此外,与3DOWC相比,OA-3DOWC的抗拉强度最差,但疲劳性能略有改善。疲劳寿命预测值与试验值的最大误差为11.16 %。对于相同应力水平下的疲劳寿命,M3DWC > OA-3DOWC > 3DOWC,由于交错纤维排列中裂纹扩展路径复杂。
Additive manufacturing of gradient porous Si/SiC ceramic parts: Quasi-static behaviors and mechanical properties
Ce Sun, Song Zhang, Rong Tu, Lihong Wu, Jiahao Ye, Yusheng Shi, Chunze Yan, Huajun Sun, Yuhan Liao, Peng Chen, Kai Liu
doi:10.1016/j.compstruct.2024.118693
梯度多孔Si/SiC陶瓷零件的增材制造:准静态行为和力学性能
Porous silicon carbide (SiC) ceramic exhibits low density, high toughness, which endow it with an indispensable role in engineering applications. However, the manufacturing, designing, and making full use of the rich pore structure of gradient porous SiC ceramic to improve its mechanical performance still face many challenges. Herein, the manufacture of gradient porous Si/SiC ceramic part is realized for the first time, and the influence of gradient structural on mechanical properties is deeply analyzed. The results indicate that the porous Si/SiC ceramics with constant gradient transition rate is characterized by step-by-step destruction and can carry larger strains than the porous Si/SiC ceramics with non-constant gradient transition rate. Meanwhile, reducing the gradient span can improve the strength, but it is easy to lead to brittle damage. In particular, gradient porous Si/SiC ceramics with constant gradient transition rate and 30 % gradient span can exhibit both good strength and toughness. The compressive strength can reach 11.71 MPa, and the equivalent elastic modulus can reach 2.28 GPa. Finally, a laminar material prediction model for mechanical properties is presented. This paper presents an effective fabrication method for gradient porous ceramic parts and provides a feasible means for the design and prediction of mechanical properties.
多孔碳化硅(SiC)陶瓷具有低密度、高韧性的特点,在工程应用中具有不可缺少的作用。然而,如何制造、设计和充分利用梯度多孔碳化硅陶瓷丰富的孔隙结构来提高其力学性能仍面临诸多挑战。本文首次实现了梯度多孔Si/SiC陶瓷零件的制造,并深入分析了梯度结构对力学性能的影响。结果表明,恒定梯度转变速率的多孔Si/SiC陶瓷比非恒定梯度转变速率的多孔Si/SiC陶瓷具有逐步破坏的特点,并且可以携带更大的应变。同时,减小梯度跨度可以提高强度,但容易导致脆性损伤。梯度过渡率为恒定,梯度跨度为30 %的梯度多孔Si/SiC陶瓷具有良好的强度和韧性。抗压强度可达11.71 MPa,等效弹性模量可达2.28 GPa。最后,提出了层流材料力学性能的预测模型。本文提出了一种有效的梯度多孔陶瓷零件的制备方法,为其力学性能的设计和预测提供了可行的手段。
A highly thermally conductive yet electrically insulating boron nitride nanosheets/polyetherimide composite with oriented structure
Tianze Wang, Hui Chi, Danying Zhao, Junguo Dong, Ming Li, Zhenhua Jiang, Yunhe Zhang
doi:10.1016/j.compositesa.2024.108581
一种具有取向结构的高导热且电绝缘的氮化硼纳米片/聚醚酰亚胺复合材料
Due to the continuous development of semiconductor technology and the rapid increase in power density of modern electronic devices, there is an urgent need for a thermal interface material (TIM) with ultra-high heat dissipation capacity and excellent electrical insulation. Here, we report a new embedded series strategy for preparing thermal interface materials. Firstly, ultra-thin boron nitride nanosheets (BNNS) are continuously and neatly embedded into oriented fibers by electrospinning to form an ordered series structure. These composite fibers are then stacked into multiple layers and simply compacted to form a dense structure. Finally, by controlling the hot pressing temperature to confine the movement of oriented fibers, the activated molecular chain segments move in confined space to prepare a composite with oriented structure. The composite provides a reliable conduction path for phonons by embedding neatly arranged BNNS in oriented structure. The composites prepared by this strategy have higher thermal anisotropy (λ=/λ⊥ = 7.16) and in-plane thermal conductivity (3.08 W/(m·K), BNNS Loading: 30 wt%), and also exhibit better electrical insulation (8.16 × 1015 Ω·cm) than those prepared by solution coating and hot pressing.
由于半导体技术的不断发展和现代电子器件功率密度的迅速提高,迫切需要一种具有超高散热能力和优良电绝缘性的热界面材料(TIM)。在这里,我们报告了一种新的嵌入式系列策略来制备热界面材料。首先,通过静电纺丝将超薄氮化硼纳米片(BNNS)连续整齐地嵌入定向纤维中,形成有序的系列结构。然后将这些复合纤维堆叠成多层,简单地压实形成致密的结构。最后,通过控制热压温度来限制取向纤维的运动,使被激活的分子链片段在受限空间内运动,从而制备出具有取向结构的复合材料。该复合材料通过在定向结构中嵌入整齐排列的BNNS,为声子提供了可靠的传导路径。通过该策略制备的复合材料具有更高的热各向异性(λ=/λ⊥= 7.16)和面内导热系数(3.08 W/(m·K), BNNS加载:30 wt%),并且与溶液涂层和热压制备的复合材料相比,还具有更好的电绝缘性(8.16 × 1015 Ω·cm)。
3D printing of graphene frameworks decorated with magnetic components for enhanced electromagnetic interference shielding
Yue Wang, Jialiang Luo, Gazi Hao, Jun Di, Guigao Liu, Suwei Wang, Wei Jiang
doi:10.1016/j.compositesa.2024.108588
用磁性元件装饰的石墨烯框架的3D打印,以增强电磁干扰屏蔽
Three-dimensional (3D) printed graphene frameworks with structural designability and compositional tunability offer new opportunities for electromagnetic interference (EMI) shielding applications. However, advanced EMI shielding materials with customizable structures and magnetic responsiveness remain a challenge. Herein, we construct lightweight and structurally controllable 3D reduced graphene oxide frameworks decorated with magnetic components (MRGO frameworks) via 3D printing technology to tailor EMI shielding properties. By adjusting the preparation conditions of the MRGO frameworks, such as inter-filament spacing, composition, and pyrolysis temperature, the graphitization degree and transmission paths are influenced, enabling electrical conductivity and magnetic property, and ensuring excellent EMI shielding performance. Specifically, the average EMI shielding effectiveness of the MRGO framework in the K-band and Ka-band is 44.95 dB and 53.90 dB, respectively. Furthermore, the 3D MRGO frameworks follow a reflection-dominated EMI shielding mechanism. This work provides insights into the development of EMI shielding materials through structural design and compositional optimization.
三维(3D)打印石墨烯框架具有结构可设计性和成分可调性,为电磁干扰(EMI)屏蔽应用提供了新的机会。然而,具有可定制结构和磁响应性的先进EMI屏蔽材料仍然是一个挑战。在此,我们通过3D打印技术构建了轻质且结构可控的磁性元件装饰的3D还原氧化石墨烯框架(MRGO框架),以定制EMI屏蔽性能。通过调整MRGO骨架的制备条件,如丝间距、组成、热解温度等,可以影响其石墨化程度和传输路径,使其具有良好的导电性和磁性能,并具有良好的电磁干扰屏蔽性能。具体来说,MRGO框架在k波段和ka波段的平均EMI屏蔽效能分别为44.95 dB和53.90 dB。此外,3D MRGO框架遵循反射主导的电磁干扰屏蔽机制。这项工作通过结构设计和成分优化为电磁干扰屏蔽材料的发展提供了见解。
Bird’s nest inspired aerogels towards ultrahigh strength and robust flame retardancy at extreme environment
Hong Zhang, Haiyun Ma, Huiqi Gao, Le Yang, Chang Wang, Yunhong Jiao, Jianzhong Xu
doi:10.1016/j.compositesb.2024.111966
受燕窝启发的气凝胶在极端环境下具有超高强度和强大的阻燃性
The mechanical properties of aerogels remain a critical concern for their application. Inspired from the hierarchical architecture of bird's nests, we have designed an effective biomimetic hybrid strategy for creating an aerogel with ultrahigh strength and robust flame retardancy. The super-molecular micro- to nanofibrils formed by boric acid and melamine act as “twigs” while a small part of biobased polysaccharide agar serves as “glue”. Via the water as the solvent and an eco-friendly freeze-drying method, the obtained boric acid-melamine/agar (BMA) aerogel with a low density (0.0760 g/cm3) exhibited exceptional high compressive strength, reaching up to 3.92 MPa at 80% strain. A piece of the BMA aerogel with 10 cm2 can resist a motorcycle (150 kg) easily without any deformation. Additionally, the BMA aerogel demonstrated outstanding inherent flame retardant property (achieving UL-94 V-0 rating with relatively low the heat release, total heat release and CO release rate values) as well as superior thermal insulating properties (with a thermal conductivity as low as 0.0364 W/m⋅K). Given the distinctive mechanical properties and excellent other properties, the BMA aerogels hold great promise for potential promise in energy-saving and thermal protection applications. and the superior stiffness mechanism behind this performance is also analyzed.
气凝胶的力学性能仍然是其应用的关键问题。受燕窝分层结构的启发,我们设计了一种有效的仿生混合策略,用于制造具有超高强度和强大阻燃性的气凝胶。由硼酸和三聚氰胺形成的超分子微至纳米原纤维充当“细枝”,而一小部分生物基多糖琼脂充当“胶水”。以水为溶剂,采用生态友好的冷冻干燥方法,得到了低密度(0.0760 g/cm3)的硼酸-三聚氰胺/琼脂(BMA)气凝胶,在80%应变下,其抗压强度高达3.92 MPa。一块10平方厘米的BMA气凝胶可以很容易地抵抗摩托车(150公斤)而不会变形。此外,BMA气凝胶具有优异的固有阻燃性能(达到UL-94 V-0等级,放热量、总放热量和CO释放率值相对较低)和优越的隔热性能(导热系数低至0.0364 W/m·K)。由于其独特的机械性能和优异的其他性能,BMA气凝胶在节能和热保护应用方面具有很大的潜力。并对其优越的刚度机理进行了分析。