今日更新:Composite Structures 6 篇,Composites Part A: Applied Science and Manufacturing 1 篇,Composites Part B: Engineering 6 篇,Composites Science and Technology 1 篇
CNTs/PVA Composite Aerogel for Efficient Microwave and Acoustic Absorption
Xu Cao, Yong Liu, Qiong Sun, Tian Che, Cao Wu, Yong Yang
doi:10.1016/j.compstruct.2023.117805
高效微波声吸收的CNTs/PVA复合气凝胶
The lightweight three-dimensional (3D) carbon nanotubes (CNTs) aerogel has garnered significant interest due to their exceptional characteristics, including high porosity, large specific surface area, and a 3D conductive network. These characteristics make it as a promising candidate for various applications in microwave absorption. However, to construct a multifunctional framework, that can swiftly adapt to complex real-world environments, remains a large challenge. In this study, we fabricated a multifunctional CNTs/polyvinyl alcohol composite aerogel (CPA). Integrating polyvinyl alcohol (PVA) into CNTs aerogel could effectively prevent CNTs aggregation, thus obtaining the remarkable electromagnetic absorption, acoustic, mechanical, and thermal properties. The minimum reflection loss (RL) of CPA achieved an outstanding value of -39.77 dB, measured with a thickness of 2 mm. In addition, CPA showed excellent sound absorption performance, with the highest sound absorption coefficient (SAC) of 0.981. Sound transmission loss (STL) could be improved by adjusting the ratio of CPA, the improvement of STL was 5-8 dB at the mid-high frequencies. Finally, CPA also exhibited excellent thermal insulation performance with the lowest thermal conductivity of 0.0297 W/m·k. The multifunctional capabilities of CPA position it as a highly promising material for various applications, such as microwave absorption, noise reduction, and heat preservation.
轻质三维(3D)碳纳米管(CNTs)气凝胶由于其独特的特性(包括高孔隙率、大比表面积和3D导电网络)而引起了人们的极大兴趣。这些特性使其在微波吸收领域具有广阔的应用前景。然而,构建一个能够快速适应复杂现实环境的多功能框架仍然是一个巨大的挑战。在这项研究中,我们制备了一种多功能CNTs/聚乙烯醇复合气凝胶(CPA)。将聚乙烯醇(PVA)加入到CNTs气凝胶中,可以有效地防止CNTs聚集,从而获得优异的电磁吸收、声学、力学和热性能。在厚度为2mm时,CPA的最小反射损耗(RL)达到了-39.77 dB的显著值。此外,CPA具有优异的吸声性能,吸声系数(SAC)最高,为0.981。通过调节CPA的比值可以提高声传输损耗(STL),在中高频时,STL的改善幅度为5 ~ 8 dB。最后,CPA也表现出优异的保温性能,最低导热系数为0.0297 W/m·k。CPA的多功能特性使其在微波吸收、降噪和保温等方面具有很高的应用前景。
Analyzing free vibration and buckling of heated laminated plate with cutouts: A Nitsche-based isogeometric approach
Yuan Wang, Chaofeng Pan, Chao Zhang, Wangfan Zhou, Xiaobo Liu, Kaibo Xia, Jiangping Xu
doi:10.1016/j.compstruct.2023.117812
热切割层合板的自由振动和屈曲分析:一种基于nitsche的等几何方法
In this research, a comprehensive Nitsche-based isogeometric analysis framework is presented for studying the free vibration and buckling characteristics of laminated plates with cutouts under uniform and non-uniform thermal loads. The approach utilizes non-overlapping non-uniform rational B-Splines patches to discretize the perforated plate and seamlessly connects them using the Nitsche method. The technique is then applied to investigate the free vibration and buckling behaviors of laminated plates with cutouts under varying thermal conditions. Three tests with different element sizes are used to analyze composite plate under uniform thermal load, demonstrating good convergence and accuracy of the present method. Rectangular laminated plates without cutouts, considering various boundary conditions, fiber orientations, and temperature variations under uniform or non-uniform thermal loads are analyzed. The natural frequencies and critical buckling temperatures are found to be in excellent agreement with existing literature. Additionally, the analysis is expanded for laminated plates with cutouts under diverse boundary conditions, considering variations in fiber orientations, cutout shapes and numbers, and types of thermal loads. Thorough investigations are carried out to understand the influence of these factors on the vibrational and buckling behaviors of the plates. Moreover, numerical study with non-conforming mesh demonstrates strong capability of the proposed method.
在本研究中,提出了一种基于nitsche的综合等几何分析框架,用于研究带切口层合板在均匀和非均匀热载荷下的自由振动和屈曲特性。该方法利用非重叠非均匀有理b样条块将穿孔板离散化,并使用Nitsche方法将它们无缝连接。然后应用该技术研究了带切口层合板在不同热条件下的自由振动和屈曲行为。采用三种不同单元尺寸的试验对复合材料薄板进行了均匀热载荷分析,结果表明该方法具有较好的收敛性和准确性。在均匀热载荷和非均匀热载荷作用下,对考虑不同边界条件、纤维取向和温度变化的无切口矩形层合板进行了分析。固有频率和临界屈曲温度与现有文献非常吻合。此外,考虑到纤维方向、切口形状和数量以及热载荷类型的变化,对不同边界条件下带切口的层合板进行了扩展分析。对这些因素对板的振动和屈曲行为的影响进行了深入的研究。此外,对非一致性网格的数值研究也证明了该方法的有效性。
Strain Rate-Dependent Failure Modelling of Impact Damage in Laminated CFRP Structures
D. Ivančević, J. Ratković, E. Giannaros
doi:10.1016/j.compstruct.2023.117817
基于应变率的CFRP层合结构冲击损伤失效模型
This work focuses on the development, implementation, and validation of a constitutive model for unidirectional composites, aiming to numerically simulate impact damage in laminated structures. The model incorporates a failure criterion that accounts for the influence of strain rate on failure initiation and distinguishes between four failure modes. Failure initiation criteria are 3D phenomenological-based criteria according to the previous work of Puck and Schürmann (1998) and Pinho (2006). Additionally, a mesh-objective damage propagation model is implemented to simulate the impact damage. The impact simulations are performed using Abaqus/Explicit, with the constitutive model implemented through the user subroutine VUMAT. Validation of the strain rate effects on failure initiation is performed using strain rate-dependent bi-axial failure curves for IM7/8552 and AS-4/3506. The analyses indicate that the properties governing the strain rate dependence of failure initiation are consistent. Therefore, the hypothesis was tested in which the same strain rate scaling approach could be used for CFRP materials for which only static properties are available. This hypothesis was tested in high and low-velocity impact simulations at laminated IMS60/977-2 CFRP plates. The results demonstrate that the model accurately replicates the experimentally observed impact-induced contact forces and effectively captures the damaged state in the impacted plate.
这项工作的重点是开发、实施和验证单向复合材料的本构模型,旨在数值模拟层压结构的冲击损伤。该模型纳入了考虑应变速率对破坏起始影响的破坏准则,并区分了四种破坏模式。根据Puck和sch<s:1> rmann(1998)和Pinho(2006)之前的工作,失效启动标准是基于三维现象学的标准。此外,还建立了网格目标损伤传播模型来模拟冲击损伤。采用Abaqus/Explicit进行冲击仿真,本构模型通过用户子程序VUMAT实现。使用应变率相关的IM7/8552和as /3506双轴失效曲线验证了应变率对失效启动的影响。分析表明,控制破坏起始的应变速率依赖特性是一致的。因此,假设进行了测试,其中相同的应变率缩放方法可以用于CFRP材料,只有静态性能可用。这一假设在IMS60/977-2 CFRP叠层板的高速和低速冲击模拟中得到了验证。结果表明,该模型准确地复 制了实验观察到的冲击接触力,有效地捕捉了冲击板的损伤状态。
Fatigue Damage Mechanisms and Evolution of Residual Tensile Strength in CFRP Composites: Stacking Sequence Effect
Zuxiang Lei, Rui Pan, Weikang Sun, Yawei Dong, Yun Wan, Binbin Yin
doi:10.1016/j.compstruct.2023.117818
CFRP复合材料疲劳损伤机理及残余抗拉强度演化:堆叠顺序效应
This study explores the effect of fiber orientation on the fatigue resistance of carbon fiber reinforced polymer composite laminates. First, fatigue damage mechanisms of composite laminates with different stacking sequences at various stress levels are analyzed by utilizing digital image correlation (DIC) and scanning electron microscope (SEM) techniques. The findings highlight that the fiber orientation of the laminate has a significant effect on the fatigue life of the specimens. Prior to final fatigue failure, laminates with 0° fiber orientation experience only a 30% reduction, while laminates with ±45° fiber orientation show up to 93% stiffness reduction. The fracture modes of laminates with a 0° fiber orientation vary depending on stress levels. Microscopic observations confirm that in the case of laminates with ±45° fiber orientations under compressive loading, fiber flexion, and delamination are the predominant failure mechanisms. Further, the post-fatigue tensile tests reveal that the residual tensile strength of the laminates with ±45° fiber orientations increases by 6.3% after 15% of the total cycles (7.2×104) at a 30% stress level. The contribution of this study provides vital insights into the structural design of laminates and offers a pathway for improving their fatigue performance.
研究了纤维取向对碳纤维增强聚合物复合材料层合板抗疲劳性能的影响。首先,利用数字图像相关(DIC)和扫描电镜(SEM)技术,分析了不同叠层顺序的复合材料层板在不同应力水平下的疲劳损伤机理。结果表明,层合板的纤维取向对试件的疲劳寿命有显著影响。在最终疲劳失效之前,纤维取向为0°的层压板刚度仅降低30%,而纤维取向为±45°的层压板刚度降低高达93%。纤维取向为0°的层压板的断裂模式随应力水平的变化而变化。微观观察证实,在压缩载荷下纤维取向为±45°的层压板的情况下,纤维弯曲和分层是主要的破坏机制。此外,疲劳后拉伸试验表明,在30%的应力水平下,经过15%的总循环(7.2×104),纤维取向为±45°的层合板的残余拉伸强度增加了6.3%。本研究为层合板的结构设计提供了重要的见解,并为提高层合板的疲劳性能提供了途径。
Investigation on interference and damage behaviours of electromagnetic riveted double-sided countersunk 30CrMnSiA/CFRP joints
Minghao Zhang, Zengqiang Cao, Yuejie Cao, Guo Zheng, Chengxiang Guo, Yuehaoxuan Wang
doi:10.1016/j.compstruct.2023.117824
电磁铆接30CrMnSiA/CFRP双面沉头接头干扰及损伤行为研究
Carbon fibre reinforced polymer (CFRP) structures benefit from electromagnetic riveting (EMR). However, incorrect riveting parameters could result in damages in CFRP structures during the EMR process. Excessive interference size may introduce initial damages to the joints. As a result, in this paper, the damage behaviours and the interference characteristics of the 30CrMnSiA/CFRP double-sided countersunk electromagnetic riveted joints are investigated. The riveting damage experiment was conducted, with the regular pressing riveting (RPR) process as a comparison. Moreover, a progressive damage FE model considering multiple typical damage modes of CFRP was developed for EMR damage prediction. The results show that when the rivet-hole diameter increases by 5% (4.08mm to 4.28mm), the average interference size of the joint under EMR and RPR processes decreases by 41% and 53%, respectively. Double-sided countersunk riveted joint interference size along the rivet axial distribution is not uniform, the CFRP sheet side of the interference size is relatively small. The EMR achieves a tighter, more uniform interference fit, while causing more severe riveting damages to the CFRP structure. Initial riveting damage exhibits a variety of modes, with delamination damage showing most significant sensitivity to rivet hole clearance.
碳纤维增强聚合物(CFRP)结构受益于电磁铆接(EMR)。然而,在EMR过程中,不正确的铆接参数可能导致CFRP结构的损伤。过大的干涉尺寸会对接头造成初始损伤。为此,本文对30CrMnSiA/CFRP双面埋头电磁铆接接头的损伤行为和干扰特性进行了研究。进行了铆接损伤实验,并与常规冲压铆接(RPR)工艺进行了对比。此外,建立了考虑碳纤维布多种典型损伤模式的渐进损伤有限元模型,用于EMR损伤预测。结果表明:当铆钉孔直径增加5% (4.08mm ~ 4.28mm)时,EMR和RPR工艺下接头的平均干涉尺寸分别减小41%和53%;双面沉铆接头过干涉尺寸沿铆钉轴向分布不均匀,CFRP片材侧的过干涉尺寸相对较小。EMR实现了更紧密、更均匀的过盈配合,同时对CFRP结构造成更严重的铆接损伤。初始铆接损伤表现出多种模式,分层损伤对铆钉孔间隙的敏感性最大。
The numerical simulation of Particulate Reinforced Composites by using a two-dimensional VCFEM formulated with plastic, thermal, and creep strain
Jie Rao, Ran Guo, Rui Zhang
doi:10.1016/j.compstruct.2023.117825
采用含塑性、热应变和蠕变应变的二维VCFEM对颗粒增强复合材料进行了数值模拟
The working environment of industrial fields where the Particulate Reinforced Composites (PRCs) are commonly used is complex. In these harsh environments, PRCs produce some nonlinear strains, such as plastic, thermal, and creep strains, which affect the performance of PRCs to some extent. In addition, the actual structure of PRCs contains a massive amount of inclusions, and the number of inclusions could reach the magnitude of millions or even tens of millions. For the large-scale numerical simulation of PRCs, ordinary displacement finite element requires a large number of meshes, which increases their computational complexity and unsolvability. For real PRCs with random particle distribution, homogenisation theory does not accurately capture the true state of stress concentration in PRCs. The Voronoi cell finite element method (VCFEM) can be a good solution to the drawbacks of the above two numerical simulation methods. The subject of the present work explores a modified complementary energy generalized function that takes the constitutive relationship of nonlinear strain into account, proposing a two-dimensional VCFEM, formulated with plastic, thermal, and creep strain. The simulation results are compared with the computed results of a commercial finite element software Marc to verify the validity and accuracy of the VCFEM. Results of the comparison show that the VCFEM has the advantages of simple meshing and faster computation under the same precision. The VCFEM, considering plastic, thermal, and creep strains proposed in this paper, lays the foundation for future large-scale numerical simulations of PRCs containing a large quantity of inclusion structures and can realistically capture the stress concentration state of PRCs. At the end of the article, the impact of the order of stress function on the calculation results is discussed.
颗粒增强复合材料(prc)在工业领域的工作环境是复杂的。在这些恶劣的环境中,prc会产生一些非线性应变,如塑性应变、热应变和蠕变应变,这些都在一定程度上影响了prc的性能。此外,prc的实际结构中含有大量的包裹体,包裹体的数量可以达到数百万甚至数千万个量级。普通位移有限元在大尺度数值模拟中需要大量的网格,这增加了有限元的计算复杂度和不可解性。对于具有随机颗粒分布的真实prc,均质化理论不能准确地捕捉prc中应力集中的真实状态。Voronoi单元有限元法(VCFEM)可以很好地解决上述两种数值模拟方法的不足。本工作的主题探讨了一个改进的互补能量广义函数,该函数考虑了非线性应变的本构关系,提出了一个二维VCFEM,包含塑性、热应变和蠕变应变。仿真结果与商用有限元软件Marc的计算结果进行了比较,验证了VCFEM的有效性和准确性。对比结果表明,在相同精度下,VCFEM具有网格划分简单、计算速度快的优点。本文提出的VCFEM考虑了塑性应变、热应变和蠕变应变,为今后对含有大量夹杂物结构的复合材料进行大规模数值模拟奠定了基础,可以真实地捕捉复合材料的应力集中状态。最后讨论了应力函数阶数对计算结果的影响。
Modeling and experimental identification of thermo-kinetic and visco-hyperelastic coupling for semicrystalline thermoplastic continuous fiber composites subjected to processing temperatures
Nicolas Bigot, Nahiène Hamila, Philippe Chaudet, Shihe Xin, M’hamed Boutaous
doi:10.1016/j.compositesa.2023.107967
加工温度下半结晶热塑性连续纤维复合材料热动力学和粘弹性耦合的建模与实验鉴定
This paper presents a visco-hyperelastic constitutive model to characterize the temperature-dependent mechanical deformation of composite materials during thermoforming. The material of interest was a unidirectional or woven fibrous reinforcement filled with a semi-crystalline thermoplastic matrix. Based on the two laws of thermodynamics, the mechanical model was coupled with the heat equation and a crystallization kinetics model. As a result, the viscoelastic effects and exothermicity of the crystallization reaction, characteristic of the presence of the semicrystalline thermoplastic matrix, constituted internal heat sources taken into account by the heat equation. These were the first steps towards establishing a thermo-chemical–mechanical coupling. In order to validate and parameterize the present law, a thermomechanical characterization of in-plane shear was put forward.
本文提出了一种粘-超弹性本构模型来表征复合材料在热成形过程中随温度变化的力学变形。感兴趣的材料是一种单向或编织纤维增强填充半结晶热塑性基质。基于热力学两定律,将力学模型与热方程和结晶动力学模型相结合。因此,结晶反应的粘弹性效应和放热性,以及半结晶性热塑性基体的存在,构成了热方程考虑的内部热源。这是建立热-化学-机械耦合的第一步。为了验证和参数化这一规律,提出了面内剪切的热力学表征。
Significantly enhanced fatigue resistance and mechanisms of hypoeutectic Al-Si composite calibrated using trace in-situ nanocrystals
Tian-Shu Liu, Lin Zhu, Hong-Yu Yang, Hong-Yu Cui, Jia Meng, Feng Qiu, Bai-Xin Dong, Shi-Li Shu, Qi-Chuan Jiang, Lai-Chang Zhang
doi:10.1016/j.compositesb.2023.111138
利用微量原位纳米晶对亚共晶Al-Si复合材料的抗疲劳性能和机制进行了显著增强
Fatigue resistance under extreme stress conditions is an important indicator to evaluate industrial application potential of Al-Si-Mg alloys, but their fatigue resistance is inherently weakened by large grain size, long-needle Si phases and coarse precipitates. This work reports significantly optimized microstructure configuration and fatigue resistance of hypoeutectic Al-Si composite optimized by the nanocrystallization products of a NiNbTi metallic glass. It was proved the in-situ NiTi (B2) nanocrystals can serve as the heterogeneous nucleation sites of α-Al and β-Mg2Si and the growth retarder of eutectic Si. Particularly, the optimized composite exhibited nearly 5 times and 6 times longer fatigue life than the unoptimized alloy at 120 MPa and 60 Hz and at 240MPa and 20 Hz, respectively. The fatigue strength (N = 107) was increased by 21.7 % and 25.9 % at 60 Hz and 20 Hz, respectively. The α-Al refinement enhanced the resistance to fatigue crack initiation. The refinement and spheroidization of eutectic Si phases reduced stress concentration. Also, the austenite-martensite phase transformation of NiTi afforded more energy for precipitation. Refined β-Mg2Si and β'' phases were facilitated to interact with dislocations, improving the resistance to dislocation slip during cyclic strain through the dislocation shearing effect. This work provides a theoretical basis for the future development of Al-Si alloys and composites with excellent fatigue resistance for expanding their industrial application scope.
极端应力条件下的抗疲劳性能是评价Al-Si-Mg合金工业应用潜力的重要指标,但晶粒尺寸大、Si相长针状、析出物粗大等因素削弱了Al-Si-Mg合金的抗疲劳性能。本文报道了利用纳米化产物优化的镍钛金属玻璃的亚共晶铝硅复合材料的微观结构和抗疲劳性能。结果表明,原位NiTi (B2)纳米晶可以作为α-Al和β-Mg2Si的非均相成核位点和共晶Si的生长缓凝剂。特别是,在120 MPa和60 Hz、240MPa和20 Hz下,优化后的复合材料的疲劳寿命分别比未优化的合金长近5倍和6倍。在60 Hz和20 Hz下,合金的疲劳强度(N = 107)分别提高了21.7% %和25.9% %。α-Al的细化增强了材料抗疲劳裂纹萌生的能力。共晶Si相的细化和球化降低了应力浓度。同时,NiTi的奥氏体-马氏体相变为析出提供了更多的能量。细化的β- mg2si和β”相与位错相互作用,通过位错剪切效应提高了循环应变过程中对位错滑移的抵抗能力。本工作为今后开发具有优异抗疲劳性能的铝硅合金及复合材料,扩大其工业应用范围提供了理论基础。
Individualized bio-scaffold encapsulating siPTEN-loaded exosomes for promoting neuronal regeneration in spinal cord injury
Zehan Shang, Zihao Liu, Min Han, Hao Fan, Dongxiao Lu, Zijian Zhou, Zhihai Wang, Yuming Li, Xiaofeng Wang, Bingcheng Wang, Baogeng Huai, Youqiang Cui, Huitang Xia, Shan Wang, Tao Xin
doi:10.1016/j.compositesb.2023.111146
包裹载sipten外泌体的个别化生物支架促进脊髓损伤神经元再生
Biological scaffold implants loaded with exosomes were acknowledged as a promising strategy for the treatment of spinal cord injury. In this study, we constructed an individualized biomimetic scaffold based on combination of multimodal imaging and 3D printing technology, featuring sustained release, biodegradability, and strongly biocompatibility. The scaffold incorporated mesenchymal stem cell-derived exosomes to alleviate inflammatory response in microenvironment and reduce scar formation of ECM molecule deposition. Furthermore, to effectively enhance neuronal repair and regeneration, siRNAs targeting PTEN were introduced into exosomes. The engineered exosomes within scaffold induced endogenous neuronal regeneration and enhanced axonal growth through PTEN/PI3K/AKT/mTOR signaling pathway. Additionally, implantation of scaffold could bridge the severed ends, thus providing spatial signals to modulate the organization of neural cells, facilitating the reconstruction of complex neural networks, and restoring nerve conduction. Collectively, the individualized 3D printed bio-scaffold encapsulated siPTEN-loaded exosomes could offer great promise for the prospective clinical translation in spinal cord injury therapy.
装载外泌体的生物支架植入物被认为是治疗脊髓损伤的一种有前途的策略。在本研究中,我们基于多模态成像和3D打印技术的结合构建了个体化仿生支架,具有缓释、可生物降解、强生物相容性的特点。支架加入间充质干细胞来源的外泌体,减轻微环境下的炎症反应,减少ECM分子沉积的瘢痕形成。此外,为了有效地促进神经元的修复和再生,将靶向PTEN的sirna引入外泌体。支架内工程化外泌体通过PTEN/PI3K/AKT/mTOR信号通路诱导内源性神经元再生,促进轴突生长。此外,支架的植入可以桥接断端,从而提供空间信号来调节神经细胞的组织,促进复杂神经网络的重建,恢复神经传导。综上所述,这种封装了sipten负载外泌体的个性化3D打印生物支架在脊髓损伤治疗的前瞻性临床转化中具有很大的前景。
Electromagnetic oscillation induced graphene-based aerogel microspheres with dual-chamber achieving high-performance broadband microwave absorption
Wenting Deng, Dandan Zhi, Jinzhe Li, Tian Li, Qian Liu, Jiatong Li, Jiang Zhu, Fanbin Meng
doi:10.1016/j.compositesb.2023.111149
电磁振荡诱导石墨烯基双腔气凝胶微球实现了高性能宽带微波吸收
Graphene-based aerogels have indeed generated significant interest in manufacturing microwave absorbers with ultra-low density and high efficiency. Nevertheless, unitary loss mechanism and impedance mismatch hinder corresponding application. Furthermore, it is essential to address the challenges related to structure control strategy and explanation of the loss mechanism. Dual-chamber graphene-based aerogel microspheres (AMs) with heterogeneous interfaces were fabricated through electrospinning-freeze drying and subsequent calcination. Significant differences are observed in reflecting and scattering of shell and dual-chamber structure against electromagnetic wave (EMW), enabling electromagnetic oscillation, sequential absorption and multi-level coupling of EMW. In addition, the dual-chamber construction is a pivotal role in optimizing impedance matching. In this regard, dual-chamber structure graphene-based AMs with 5 wt% loading were synthesized and exhibited excellent loss ability to EMW in the range of 5∼18 GHz, which manifest −28.12 dB at 15.62 GHz, and accordingly, the fE is 6.0 GHz at 2.2 mm thickness, achieving full coverage dissipation of Ku-band. The results demonstrate that the dual-chamber graphene-based AMs achieve the effect of multi-frequency compatible and broadband microwave absorption at low thickness. The integration of the ideation of heterogeneous dual-chamber AMs with electromagnetic-oscillation and sequential loss provides a unique and innovative strategy for modulating lightweight and broadband efficiency absorbers.
基于石墨烯的气凝胶在制造超低密度和高效率的微波吸收剂方面确实引起了极大的兴趣。然而,单一的损耗机制和阻抗失配阻碍了相应的应用。此外,必须解决与结构控制策略和解释损失机制相关的挑战。采用电纺丝-冷冻干燥-煅烧法制备了具有非均相界面的双腔石墨烯基气凝胶微球。壳体结构和双腔结构对电磁波的反射和散射存在显著差异,从而实现电磁波的电磁振荡、顺序吸收和多级耦合。此外,双腔结构在优化阻抗匹配中起着关键作用。在这方面,合成了负载为5 wt%的双腔结构石墨烯基AMs,并在5 ~ 18 GHz范围内表现出优异的EMW损耗能力,在15.62 GHz时表现为−28.12 dB,因此fE为6.0 GHz,厚度为2.2 mm,实现ku波段全覆盖损耗。结果表明,双腔石墨烯基AMs在低厚度下实现了多频兼容和宽带微波吸收的效果。结合电磁振荡和时序损耗的非均质双腔AMs的思想,为调制轻量级和宽带效率吸收器提供了一种独特而创新的策略。
Aramid nanofiber-based functional composite materials: Preparations, applications and perspectives
Hui Zhang, Meiyun Zhang, Jinbao Li, Bin Yang, Syed Comail Abbas, Chenglong Fu, Ting Chen, Yuanyuan Xia, Jiawei Liu, Xiaoyun Du, Zhibin He, Yonghao Ni
doi:10.1016/j.compositesb.2023.111151
芳纶纳米纤维基功能复合材料的制备、应用与展望
Aramid Nanofibers (ANFs), akin to PPTA Poly (p-phenylene terephthalamide), stand at the forefront of cutting-edge nanomaterials, boasting exceptional properties like high tensile strength, modulus of elasticity, high temperature stability, and chemical stability. Their remarkable advantages have already paved the way for diverse applications in composite materials, energy devices, protection, adsorption, and groundbreaking medical products. Due to the unique properties of ANFs, there has been strong interests in the research community on the functional ANF- based composites and their applications in cutting-edge fields, there has been a lack of comprehensive reviews on the fundamental development and practical applications of ANFs regarding these most recent results (e.g., the last three years). This review aims to fill that void by thoroughly exploring the potential of ANFs. We delve into the preparation methods, uncovering techniques for preparing ANFs with specific properties and morphologies. Additionally, we critically evaluate the fascinating mechanisms driving these extraordinary properties, which stem from their nanoscale dimensions and high aspect ratio. Furthermore, we closely examine the distinct characteristics of ANFs-based composites in various forms, i.e., 1D, 2D, and 3D structure, especially in relevance to their specific applications. Also, this paper discusses the major challenges and future prospects of ANFs composites. This comprehensive review and outlook will inspire readers to gain a better understanding of the latest development status and future research directions of ANFs and ANFs-based materials.
芳纶纳米纤维(ANFs),类似于PPTA聚对苯基对苯二甲酰胺,站在尖端纳米材料的最前沿,具有优异的性能,如高抗拉强度、弹性模量、高温稳定性和化学稳定性。它们的显著优势已经为复合材料、能源设备、保护、吸附和突破性医疗产品的各种应用铺平了道路。由于ANF的独特性质,研究界对功能性ANF基复合材料及其在前沿领域的应用产生了浓厚的兴趣,但关于这些最新成果(例如,最近三年),对ANF的基本发展和实际应用缺乏全面的综述。本文旨在通过深入探索ANFs的潜力来填补这一空白。我们深入研究了制备方法,揭示了制备具有特定性质和形态的ANFs的技术。此外,我们批判性地评估了驱动这些非凡特性的迷人机制,这些特性源于它们的纳米级尺寸和高纵横比。此外,我们仔细研究了各种形式的基于anfs的复合材料的独特特征,即1D, 2D和3D结构,特别是与它们的特定应用相关。同时,本文还讨论了ANFs复合材料的主要挑战和未来的发展前景。这篇综述和展望将有助于读者更好地了解纳米纤维和纳米纤维基材料的最新发展现状和未来研究方向。
Low velocity impact and compression-after-impact response of hybrid pseudo-woven meso-architectured carbon/epoxy composite laminates manufactured via automated fiber placement
Karan Kodagali, Cyrus Vakili Rad, Subramani Sockalingam, Zafer Gurdal, Eileen Miller
doi:10.1016/j.compositesb.2023.111154
自动化纤维铺放复合假编织细观结构碳/环氧复合材料层合板低速冲击及冲击后压缩响应
An experimental study is presented on the low velocity impact (LVI) and compression after impact (CAI) response of T800-SC carbon/epoxy laminates manufactured via automated fiber (AFP) placement manufacturing. Two hybrid laminate configurations consisting of unidirectional and pseudo-woven meso-architectured composite (MAC) sub-laminates are compared against a traditional quasi-isotropic control laminate. MAC sub-laminates are manufactured via a modified AFP process implementing tow skips. The MAC architecture is macroscopically heterogeneous with discontinuous and spatially varying fiber orientations both in-plane and through thickness resulting in multiple interfaces and an expanded design space. The laminates are tested under LVI energies of 15–55 J using a 25.4 mm diameter hemispherical projectile according to ASTM D7136. The results show similar load-displacement responses but significant difference in the LVI damage profiles and CAI strengths for the different configurations. The hybrid laminate configurations exhibit increased damage resistance with up to 37% higher critical delamination load and increased damage tolerance with 26% higher residual compressive strength after an impact of 55 J compared to control laminate.
对自动化纤维铺层制造的T800-SC碳/环氧复合材料的低速冲击(LVI)和冲击后压缩(CAI)响应进行了实验研究。比较了两种由单向和伪编织细观结构复合材料(MAC)子层压板组成的混合层压板结构与传统的准各向同性控制层压板结构。MAC亚层压板是通过改进的AFP工艺制造的,实现了两个跳过。MAC结构在宏观上是不均匀的,在平面内和厚度上的光纤方向是不连续和空间变化的,导致了多个接口和扩展的设计空间。根据ASTM D7136,在LVI能量为15-55 J的情况下,使用直径25.4 mm的半球形弹丸对层压板进行测试。结果表明,不同结构下的荷载-位移响应相似,但LVI损伤曲线和CAI强度存在显著差异。与对照层压板相比,混合层压板的抗损伤能力提高了37%,临界分层载荷提高了37%,在55 J的冲击后,其损伤容忍度提高了26%。
The multi-objective optimization framework: A step towards minimizing life-cycle costs and energy consumption of carbon fibre automotive structures
Kaushik Iyer, Mathilda Karlsson Hagnell, Malin Åkermo
doi:10.1016/j.compositesb.2023.111158
多目标优化框架:朝着最小化碳纤维汽车结构生命周期成本和能源消耗迈出的一步
Design of a sustainable and economical composite structure is challenging due to the often contradicting design drivers such as energy consumption and cost. Therefore, predicting the environmental and economic impact in the early stages of product design results in the significant reduction of energy consumption and cost. Consequently, the impact of contrasting objectives on an optimized carbon fibre reinforced polymer (CFRP) demonstrator is evaluated in this study. This evaluation is performed by integrating a predictive life-cycle assessment and costing framework in a multi-objective optimization methodology. The varying design configurations include designs with and without stiffeners. Furthermore, the impact of end-of-life allocation on the optimized design is also evaluated in this study. The results show a marked difference between the energy consumption of the various optimized designs with energy optimization producing the most efficient solution. However, the mass of the demonstrator increases by 7–9 kg across the different design configurations when the closed loop allocation model is implemented. Consequently, the results show the importance of selecting an appropriate EOL allocation methodology in evaluating the energy consumption of a products. The results also show that the parameters driving the energy consumption (mass and material configuration) and cost (complexity and manufacturability) are varied and often contrasting. The differences in mass, cost, and energy optimized designs further reinforces the importance of coupling cost and energy evaluation in design of sustainable products. Finally, the study demonstrates the need for a holistic life-cycle based assessment in early stage sustainable product design.
由于能源消耗和成本等相互矛盾的设计驱动因素,设计可持续和经济的复合材料结构具有挑战性。因此,在产品设计的早期阶段预测环境和经济影响可以显著降低能耗和成本。因此,对比目标对优化的碳纤维增强聚合物(CFRP)演示器的影响在本研究中进行了评估。这种评估是通过在多目标优化方法中集成预测性生命周期评估和成本框架来执行的。不同的设计配置包括有和没有加强筋的设计。此外,本研究还评估了寿命末端分配对优化设计的影响。结果表明,各种优化设计的能耗存在显著差异,能量优化产生最有效的解决方案。然而,当实现闭环分配模型时,演示器的质量在不同的设计配置中增加了7-9 kg。因此,结果表明选择适当的EOL分配方法在评估产品的能源消耗的重要性。结果还表明,驱动能耗(质量和材料配置)和成本(复杂性和可制造性)的参数是多种多样的,并且经常形成对比。质量、成本和能源优化设计的差异进一步强化了可持续产品设计中耦合成本和能源评估的重要性。最后,研究证明了在早期可持续产品设计中需要一个基于整体生命周期的评估。
Manufacturing multifunctional vascularized composites by through-thickness frontal polymerization and depolymerization: A numerical study on the impact of sacrificial fiber configurations
Zhuoting Chen, Xiang Zhang
doi:10.1016/j.compscitech.2023.110394
通过厚度正面聚合和解聚制备多功能血管化复合材料:牺牲纤维构型影响的数值研究
Concurrent through-thickness frontal polymerization and vascularization (FP-VaSC) is emerging as a promising alternative to conventional multi-step fabrication approaches for vascularized thermoset polymers and composites. This method relies on a localized and self-propagating exothermic polymerization reaction front of the polymer matrix, to simultaneously cure the matrix, and depolymerize pre-embedded sacrificial templates. It delivers fully cured thermoset polymers and composites rapidly and energy-efficiently with the desired vascular system in a single step. While previous studies demonstrated the capability of this method for making woven laminates with a single vascular channel created by embedding a single straight sacrificial fiber, it is desirable to explore the potential of this method for making composites with multiple channels for more practical applications. We employ a previously validated thermo-chemical model from our prior study, to systematically investigate the reaction process with the presence of multiple sacrificial fibers. Two sacrificial fiber configurations are considered, namely, inline and staggered fiber configurations. Within each configuration, we consider a range of horizontal and vertical fiber spacing, which also lead to different sacrificial fiber volume fractions. This study reveals the interactions between the sacrificial fiber and the reactions, identifies the working window of this method for different sacrificial fiber configurations, and provides guidance for manufacturing laminates with multiple vascular channels. We also propose an analytical model that can quickly approximate the maximum sacrificial fiber volume fraction that can lead to successful FP-VaSC for a given carbon fiber volume fraction and compare the results with those from the thermo-chemical modeling.
同时通过厚度正面聚合和血管化(FP-VaSC)正在成为血管化热固性聚合物和复合材料的传统多步骤制造方法的有前途的替代方法。该方法依靠聚合物基体的局部自扩散放热聚合反应,同时固化基体,解聚预嵌牺牲模板。它可以在一个步骤中快速、高效地提供完全固化的热固性聚合物和复合材料,并提供所需的血管系统。虽然之前的研究表明,这种方法可以通过嵌入一根笔直的牺牲纤维来制造具有单一血管通道的编织层叠板,但为了更实际的应用,探索这种方法在制造具有多通道的复合材料方面的潜力是可取的。我们采用先前研究中验证过的热化学模型,系统地研究了存在多个牺牲纤维的反应过程。考虑了两种牺牲光纤结构,即嵌线光纤结构和交错光纤结构。在每种配置中,我们考虑了水平和垂直纤维间距的范围,这也导致了不同的牺牲纤维体积分数。本研究揭示了牺牲纤维与反应之间的相互作用,确定了该方法在不同牺牲纤维构型下的工作窗口,为制造多血管通道层叠板提供了指导。我们还提出了一个分析模型,该模型可以快速近似最大牺牲纤维体积分数,从而在给定的碳纤维体积分数下成功实现FP-VaSC,并将结果与热化学模型的结果进行比较。