今日更新:Composite Structures 4 篇,Composites Part A: Applied Science and Manufacturing 1 篇,Composites Part B: Engineering 2 篇,Composites Science and Technology 1 篇
Uniform winding path generation for Non-Axisymmetric mandrels
Shuo Li, Zhuo Meng, Yujing Zhang, Yize Sun
doi:10.1016/j.compstruct.2024.118834
非轴对称心轴均匀缠绕路径生成
Creating a continuous and uniform winding path may be a challenging task due to the complex surface characteristics, resulting in limitations in designing winding paths for non-axisymmetric mandrel. A design method is proposed to generate uniform winding path for non-axisymmetric mandrel by transforming the mandrel surface into discrete triangle meshes. This method involves generating winding paths in three parts: the basic path, the replication paths, and the transitional paths. Firstly, the variable winding angle of basic path is obtained according to the mandrel cross-sectional characteristics to generate the basic path with uniform fiber coverage; Secondly, the cross-sectional equidistant points are calculated according to the position of basic path on the mandrel cross-section, and the replication paths through the equidistant points are generated based on dichotomy principle to obtain uniform fiber distribution in the circumferential direction of mandrel; Thirdly, according to the required winding pattern, each transitional path is generated to connect its two corresponding replication paths. Finally, the continuous winding path is formed by the basic path, replication paths, and transitional paths. The method is applied to different non-axisymmetric mandrels, and the results show that this method can flexibly generate uniform winding paths with desired winding angle and winding pattern.
由于复杂的表面特性,创建连续均匀的缠绕路径可能是一项具有挑战性的任务,从而限制了非轴对称芯轴缠绕路径的设计。提出了一种将心轴表面转化为离散三角形网格的非轴对称心轴均匀缠绕路径设计方法。该方法包括生成三部分绕组路径:基本路径、复 制路径和过渡路径。首先,根据芯棒截面特性获得可变缠绕角的基本路径,生成纤维覆盖均匀的基本路径;其次,根据基本路径在芯棒截面上的位置计算截面等距点,并基于二分法原理生成通过等距点的复 制路径,获得芯棒圆周方向均匀的纤维分布;第三,根据需要的缠绕模式,生成每条过渡路径,连接其对应的两条复 制路径。最后由基本路径、复 制路径和过渡路径组成连续缠绕路径。将该方法应用于不同的非轴对称芯轴,结果表明,该方法可以灵活地生成具有理想缠绕角和缠绕方式的均匀缠绕路径。
A localised continuum damage mechanics model for fibre failure in explicit integration
Jagan Selvaraj, Timothee Chastel, Stephen R. Hallett
doi:10.1016/j.compstruct.2024.118816
显式积分中纤维破坏的局部连续损伤力学模型
In finite element analyses, Continuum Damage Mechanics (CDM) typically models failure by smearing the damage over the volume of each element. Although this works well when the mesh sizes are small and closer to size of the cracks, numerical accuracy of CDM at larger mesh sizes and length-scales is limited. For instance, fibre failure in laminated composite materials is accompanied by a large amount of energy release over a small volume and the numerical accuracy in modelling this localised phenomenon is tied to the spatial resolution of the mesh. To overcome this inherent mesh dependency in damage propagation, a localisation band is introduced within the continuum elements such that elastic and damage regions can be separated using kinematic enhancement, without modelling geometric discontinuities. This separation enables cracks to be modelled as localised features and thus the stress concentrations and damage propagation are modelled more accurately than conventional CDM. This framework is here combined with a higher-order continuum element such that improved predictions can be obtained for the damage initiation stress compared to linear elements. This combined method is demonstrated using Over-height Compact Tension (OCT) and Open-Hole Tensile (OHT) tests where the dominant mechanism is fibre failure. The results are compared against experiments as well as ply-level discrete crack models.
在有限元分析中,连续损伤力学(CDM)通常通过涂抹每个单元的体积损伤来模拟失效。虽然这种方法在网格尺寸较小且接近裂纹尺寸时效果良好,但在较大网格尺寸和长度尺度下,CDM的数值精度受到限制。例如,层压复合材料中的纤维破坏伴随着小体积上的大量能量释放,模拟这种局部现象的数值精度与网格的空间分辨率有关。为了克服损伤传播中固有的网格依赖性,在连续单元中引入了局部化带,这样可以使用运动学增强将弹性区域和损伤区域分开,而无需建模几何不连续。这种分离可以将裂缝建模为局部特征,从而比传统的CDM更准确地模拟应力集中和损伤传播。该框架与高阶连续单元相结合,与线性单元相比,可以得到更好的损伤起裂应力预测。这种组合方法通过超高度致密拉伸(OCT)和裸眼拉伸(OHT)测试进行了验证,其中主要机制是纤维破坏。计算结果与实验结果以及层级离散裂纹模型进行了比较。
Ultra broadband low-frequency vibration and pulse mitigation of electromagnetic induction-based metastructure
Yu Sun, Haokai Zheng, Qiang Han, Chunlei Li
doi:10.1016/j.compstruct.2024.118821
基于电磁感应的超宽带低频振动与脉冲抑制元结构
Elastic metastructures have attracted extensive research interest for their unique properties of generating bandgaps to mitigate vibration. However, it is difficult for conventional metastructures to obtain ultra-wide bandgap in low-frequency domain. To address this challenge, a novel bandgap active control mechanism is proposed and applied to locally resonant metastructures. The magnetic resonator perfectly combines the dual mechanism of negative stiffness and electromagnetic induction, which allows the start and end frequencies of bandgap to be tuned flexibly to obtain ultra-broadband and low-frequency wave mitigation domain. The theoretical bandgap is derived from extended plane wave expansion method and verified by numerical simulation and experiment. The results show that the bandwidth is broadened by about 3.5 times than before and the quasi-bandgap with extremely-low frequency is induced under the action of electromagnetic damping. By regulating the spacing, the quasi-bandgap and bandgap can be coupled to form strong wave mitigation domain covering the frequency below 300Hz. Besides, the proposed metastructures exhibit stronger pulse mitigation enhancement and resonance peak attenuation in low-frequency domain. This study is expected to provide a new design concept for the performance development of smart elastic/acoustic wave devices such as low-frequency vibration energy harvester, vibration isolator and metasurface, etc.
弹性元结构以其产生带隙以减轻振动的独特特性引起了广泛的研究兴趣。然而,传统的元结构很难在低频域获得超宽的带隙。为了解决这一挑战,提出了一种新的带隙主动控制机制,并将其应用于局部谐振元结构。该磁谐振器完美地结合了负刚度和电磁感应的双重机制,可以灵活地调整带隙的起始和结束频率,从而获得超宽带和低频的消波域。理论带隙由扩展平面波展开法推导,并通过数值模拟和实验验证。结果表明,在电磁阻尼的作用下,带宽比以前宽了约3.5倍,并产生了极低频的准带隙。通过调节带隙和准带隙的间距,可以形成覆盖300Hz以下频率的强消波域。此外,所提出的元结构在低频域表现出更强的脉冲减缓增强和共振峰值衰减。该研究有望为低频振动能量采集器、隔振器、超表面等智能弹性/声波器件的性能开发提供新的设计理念。
Auxetic behavior and energy absorption characteristics of a lattice structure inspired by deep-sea sponge
Jiaming Ma, Hongru Zhang, Ting-Uei Lee, Hongjia Lu, Yi Min Xie, Ngoc San Ha
doi:10.1016/j.compstruct.2024.118835
受深海海绵启发的晶格结构的补充行为和能量吸收特性
Auxetic metamaterials, characterized by their lateral contraction under compression, have seen notable progress in recent years, largely due to advancements in 3D printing technologies. However, their practical application remains constrained by limited design versatility, moderate improvements in negative Poisson’s ratio (NPR), and relatively low structural stiffness. To address these challenges, a bio-inspired lattice structure (BLS) has been developed, drawing inspiration from the skeletal system of deep-sea hexactinellid sponges, renowned for their exceptional energy absorption capabilities, stiffness, and mechanical properties. Although this structure exhibits auxetic behavior, a comprehensive understanding of its mechanical performance, including its auxetic properties, remains incomplete. In this study, we systematically explore the auxetic behavior, stiffness, and energy absorption properties of the BLS through a combination of quasi-static compression experiments and detailed numerical simulations using finite element analysis. The experimental results reveal that the BLS outperforms conventional auxetic structures, such as re-entrant hexagonal honeycombs, in terms of NPR, stiffness, and energy absorption capacity. Furthermore, a parametric study is conducted to evaluate the influence of geometric variations, such as member thickness and spacing, on the mechanical performance of the BLS. These findings demonstrate that the BLS has the potential to pioneer a new class of auxetic materials, offering superior mechanical properties and broad applicability in engineering fields that require enhanced energy absorption and structural stiffness under compressive loading.
近年来,由于3D打印技术的进步,以压缩下的侧向收缩为特征的增塑型超材料取得了显著进展。然而,它们的实际应用仍然受到有限的设计通用性、负泊松比(NPR)的适度改善和相对较低的结构刚度的限制。为了应对这些挑战,一种仿生晶格结构(BLS)已经被开发出来,其灵感来自深海海绵体的骨骼系统,以其卓越的能量吸收能力、刚度和机械性能而闻名。尽管这种结构表现出形变行为,但对其力学性能,包括其形变特性的全面了解仍然不完整。在本研究中,我们通过准静态压缩实验和详细的有限元数值模拟相结合,系统地探讨了BLS的消声行为、刚度和能量吸收特性。实验结果表明,该结构在NPR、刚度和能量吸收能力等方面均优于传统的六边形重入式蜂窝结构。此外,还进行了参数化研究,以评估构件厚度和间距等几何变化对BLS力学性能的影响。这些发现表明,BLS有潜力开拓一种新型的增减材料,提供卓越的机械性能和广泛的适用性,在压缩载荷下需要增强能量吸收和结构刚度的工程领域。
From properties to performance: Understanding the multifunctional performance of carbon fiber cathodes for structural batteries
Nur Ayu Afira Sutrisnoh, Gwendolyn J.H. Lim, Kwok Kiong Chan, Karthikayen Raju, J.J.Nicholas Lim, J.Justin Koh, Derrick W.H. Fam, Madhavi Srinivasan
doi:10.1016/j.compositesa.2024.108696
从性质到性能:了解结构电池用碳纤维阴极的多功能性能
Structural batteries are multifunctional rechargeable batteries that can simultaneously store electrochemical energy and carry mechanical load. The cathode component of structural batteries is usually fabricated by functionalizing lightweight carbon fibers with cathode materials and regarded as carbon fiber cathodes (CFC). With a myriad of fabrication techniques, cathode active materials and types of carbon fibers readily available, endless variation of CFC can be produced, each with differing electrochemical and mechanical properties. Here, a fundamental study to systematically relate materials’ properties to resultant multifunctional performance of CFC were probed. Intrinsic physicochemical and mechanical properties of carbon fibers were first investigated before factors affecting the multifunctional performance of CFC were determined. Through this, a high-performing CFC with specific capacity of 155 mAh g−1 and stiffness of 72 GPa was developed. Correlation studies between the multifunctional properties were also assessed to provide comprehensive understanding and serve as a guide for future fabrication of CFC.
结构电池是一种能同时储存电化学能量和承载机械负荷的多功能可充电电池。结构电池的正极部件通常是用轻质碳纤维功能化正极材料制成的,称为碳纤维阴极(CFC)。有了无数的制造技术、阴极活性材料和碳纤维类型,可以生产出无穷无尽的CFC变化,每一种都具有不同的电化学和机械性能。在这里,系统地将材料的性质与CFC的多功能性能联系起来的基础研究进行了探讨。首先研究了碳纤维的内在物理化学和力学性能,然后确定了影响CFC多功能性能的因素。开发出比容量为155 mAh g−1、刚度为72 GPa的高性能CFC。本文还对其多功能特性之间的相关研究进行了评估,为今后CFC的制备提供了全面的认识和指导。
Innovative MoS2/C Composite with High Elasticity and Ion Permeability for Next-Gen Sodium Anodes
Xingbo Yu, Shengqin Guan, Guoli Zhang, Huihui Li, Jianlong Wang, Zhichang Liu, Baoen Xu, Kaixi Li, Taotao Guan
doi:10.1016/j.compositesb.2024.112101
新一代钠阳极用高弹性和离子渗透率的MoS2/C复合材料
Carbon-coating technology is revolutionizing the large-scale application of transition metal sulfides (TMSs) in sodium-ion storage by mitigating structural expansion and enhancing conductivity. However, the weak interaction between the core-shell and the excessive rigidity of the carbon shell have limited the stability and application potential of these composites. To overcome these challenges, we employed a confined-space chemical vapor deposition method to prepare MoS2/C composites with a balanced mix of soft and hard carbon. This innovative carbon shell ensures both flexibility and permeability, facilitating the efficient hosting of sodium ions. Moreover, numerous C-S bonds between the carbon shell and TMS core further minimize irreversible deformation during repeated sodium ion insertion and extraction. The resulting Mo1C2H1S1-1000 composite demonstrates exceptional cycling stability and rate performance. After 100 cycles at 0.1 A g-1, its capacity increases by 20-fold compared to pure MoS2, and at 5 A g-1, it outperforms pure MoS2 by more than 200-fold. Density functional theory (DFT) calculations further validate the enhanced sodium storage capacity and conductivity conferred by the carbon coating. This comprehensive strategy also enhances the structural stability of other composites, such as FeS/C and NiS/C, paving the way for next-generation sodium-ion battery anodes.
碳涂层技术通过减轻结构膨胀和提高导电性,革新了过渡金属硫化物(tms)在钠离子存储中的大规模应用。然而,核壳之间的弱相互作用和碳壳的过度刚度限制了这些复合材料的稳定性和应用潜力。为了克服这些挑战,我们采用密闭空间化学气相沉积方法制备了软硬碳平衡混合的MoS2/C复合材料。这种创新的碳壳确保了灵活性和渗透性,促进了钠离子的有效承载。此外,碳壳和TMS核之间的大量C-S键进一步减少了反复插入和提取钠离子时的不可逆变形。得到的Mo1C2H1S1-1000复合材料具有优异的循环稳定性和速率性能。在0.1 A g-1下循环100次后,其容量比纯MoS2增加了20倍,在5 A g-1下,其性能比纯MoS2高出200倍以上。密度泛函理论(DFT)计算进一步验证了碳涂层增强的钠储存能力和电导率。这种综合策略还提高了其他复合材料的结构稳定性,如FeS/C和NiS/C,为下一代钠离子电池阳极铺平了道路。
Novel flexible polyether segment polybenzoxazine shape memory nanocomposites reinforced by incorporating functionalized carbon nanotubes
Wei Zhao, Ai Ping Zhang, Xin Kang Li, Jun Bian, Shang Ke Yang, Ke Yang Ni, Ke Cheng Yang, Hai Lan Lin, Dai Qiang Chen
doi:10.1016/j.compositesb.2024.112104
采用功能化碳纳米管增强柔性聚醚段聚苯并恶嗪形状记忆纳米复合材料
This work focused on designing and investigating a novel flexible polyether segment polybenzoxazine (PBZ) shape memory nanocomposites reinforced by incorporating amination modification multiwalled carbon nanotubes (MWCNTs-NH2) through in-situ solution polymerization. FTIR, XRD, Raman, SEM, TEM, XPS and TGA spectroscopy tests elucidated the chemical structure of functionalized MWCNTs and indicated the success preparation of functionalized MWCNTs. The preparation of PBZ and PBZ/MWCNTs-NH2 was validated by NMR, FTIR, and XPS. The introduction of MWCNTs-NH2 enhanced the compatibility between MWCNTs and the PBZ matrix, thereby contributing to the property improvements. The resultant PBZ nanocomposites showed the highest tensile strength of 46.9 MPa and a maximum elongation at break of 5.6 % respectively at 3 wt% filler content, and the maximum elastic modulus of 1400.1 MPa was obtained at the filler content of 1 wt%. DMA testing verified a noteworthy enhancement in both Tg and storage modulus upon incorporating of MWCNTs-NH2 due to improved interface bonding strength between PBZ matrix and MWCNTs-NH2. Through TGA analysis, it can be concluded that the introduction of MWCNTs-NH2 enhances thermal stability. Morphological analysis unveiled a compact and dense microstructure within the nanocomposites in correlation with functionalized MWCNTs and their concentration. The optimal shape memory performance with 93.54 % Rf, 87.09 % Rr, and 4.3°/s V were observed at a MWCNTs-NH2 content of 3 wt% (100 °C). In summary, this comprehensive investigation demonstrated the impact of functionalized MWCNTs on the mechanical, thermal, electrical, and shape memory properties of the PBZ shape memory nanocomposites.
本研究致力于通过原位溶液聚合设计并研究一种新型柔性聚醚段聚苯并噁嗪(PBZ)形状记忆纳米复合材料,该材料通过掺入胺化改性多壁碳纳米管(MWCNTs-NH2)进行增强。傅里叶变换红外光谱(FTIR)、X 射线衍射(XRD)、拉曼光谱、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X 射线光电子能谱(XPS)和热重分析(TGA)等测试阐明了功能化 MWCNTs 的化学结构,并表明成功制备了功能化 MWCNTs。核磁共振(NMR)、FTIR 和 XPS 证实了 PBZ 和 PBZ/MWCNTs-NH2 的制备。MWCNTs-NH2 的引入增强了 MWCNTs 与 PBZ 基体之间的相容性,从而有助于性能的提升。所得 PBZ 纳米复合材料在 3%(质量分数)的填料含量下分别表现出最高的拉伸强度 46.9 MPa 和最大断裂伸长率 5.6%,在 1%(质量分数)的填料含量下获得最大弹性模量 1400.1 MPa。动态热机械分析(DMA)测试证实,由于 PBZ 基体与 MWCNTs-NH2 之间界面结合强度的提高,在掺入 MWCNTs-NH2 后,玻璃化转变温度(Tg)和储能模量均显著提高。通过热重分析(TGA)可以得出结论,引入氨基化多壁碳纳米管(MWCNTs-NH2)增强了热稳定性。形态分析揭示了纳米复合材料内部具有致密的微观结构,这与功能化的多壁碳纳米管及其浓度相关。在 3 重量%的 MWCNTs-NH2 含量(100°C)下,观察到了最佳的形状记忆性能,回复率(Rf)为 93.54%,回复应力(Rr)为 87.09%,回复速率(V)为 4.3°/s。总之,这项全面的研究展示了功能化多壁碳纳米管对聚偏苯三酸乙酯(PBZ)形状记忆纳米复合材料的机械、热学、电学和形状记忆性能的影响。
Impact response of carbon fiber/aluminum honeycomb sandwich structures under multiple low-velocity loads
Shanshan Shi, Guoxin Wang, Chengtao Hu, Bingzhi Chen, Xiaozhi Hu, Zhi Sun
doi:10.1016/j.compscitech.2024.111027
多重低速载荷作用下碳纤维/铝蜂窝夹层结构的冲击响应
The carbon fiber/aluminum honeycomb sandwich structures are susceptible to repeated impacts from external objects, which can significantly affect their performance and safety in engineering applications. Firstly, this study prepares two sandwich panels with different face/core interfaces: plain carbon fiber/aluminum honeycomb panels and Kevlar short-fiber-toughened interfaces and then discusses the effects of impact location and interface properties on the panels' multi-impact and post-impact compression performance, utilizing Digital Image Correlation (DIC) to elucidate the toughening effect of Kevlar short fibers. Lastly, the study examines the relationship between pit depth and residual compressive strength in both the Kevlar short-fiber-toughened and plain specimens. Experimental observations and theoretical analysis further explain the deeper deformation mechanism of sandwich specimens after impact. The mechanism reveals the main reason for the independent CAI strength of toughened specimens with pit depth. The results indicate that impact location and interface properties significantly affect the multi-impact and post-impact compression performance of the honeycomb sandwich panels. The correlation between the residual compressive strength of the Kevlar short-fiber-toughened specimens and the variations in impact position and pit depth is weaker. This distinct behavior from the plain specimens is attributed to the effective suppression of delamination damage caused by pit depth due to Kevlar short-fiber interface toughening, as well as the effective controlling of the impact damage zone by composite fillets.
碳纤维/铝蜂窝夹层结构在工程应用中容易受到外界物体的反复冲击,严重影响其性能和安全性。本研究首先制备了两种面/芯界面不同的夹层板:普通碳纤维/铝蜂窝板和芳纶短纤维-增韧界面,然后讨论了冲击位置和界面性能对面板多次冲击和冲击后压缩性能的影响,利用数字图像相关(DIC)技术阐明了芳纶短纤维的增韧效果。最后,研究了凯夫拉纤维短纤维增韧和普通试样的坑深与残余抗压强度之间的关系。实验观察和理论分析进一步解释了夹层试件撞击后更深层次的变形机理。这一机理揭示了增韧试样随坑深变化而产生独立CAI强度的主要原因。结果表明,冲击位置和界面特性对蜂窝夹芯板的多次冲击和后冲击压缩性能有显著影响。凯夫拉纤维短纤维增韧试样的残余抗压强度与冲击位置和坑深变化的相关性较弱。这种不同于平面试样的行为是由于有效抑制了由Kevlar短纤维界面增韧引起的凹坑深度引起的分层损伤,以及复合圆角有效控制了冲击损伤区。