今日更新:Composite Structures 6 篇,Composites Part A: Applied Science and Manufacturing 1 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 1 篇
Effects of fiber layout on strength and failure of 3D printed notched composites
Battini Davide, Giorleo Luca, Avanzini Andrea
doi:10.1016/j.compstruct.2023.117644
纤维布局对 3D 打印缺口复合材料强度和失效的影响
This study investigates the effect of printing strategies on the strength of additively manufactured notched fiber reinforced composite specimens. Specimens with varying notch geometries (two radii and two opening angles) and fiber layouts (unreinforced, unidirectional, quasi-isotropic and concentric) were 3D printed and tested under tension. Digital image correlation provided surface strain field data. Results showed that fiber deposition patterns significantly impact notch sensitivity, failure loads and mechanisms, with notch geometry being of secondary importance. The unidirectional layout achieved the highest strength but with progressive failure, while quasi-isotropic specimens failed abruptly from the notch. The concentric layout shielded the notch region but induced premature failure away from the notch due to transverse stress. Stress concentration factor approaches, which work well for conventional laminates, have limitations for 3D printed composites due to local differences and complex interactions. Optimizing fiber deposition, instead of geometry, emerges as a promising design route. Combining unidirectional and contouring algorithms may improve performance. However, further studies utilizing multiscale modelling and local failure analyses are needed to fully understand failure mechanisms and guide optimal notch designs for 3D printed composites. With improved understanding and design methods, 3D printing promises to unlock new possibilities for structurally efficient notched composite parts.
本研究探讨了打印策略对加成法制造的缺口纤维增强复合材料试样强度的影响。试样具有不同的切口几何形状(两个半径和两个开口角度)和纤维布局(非增强、单向、准各向同性和同心),经三维打印后进行拉伸测试。数字图像相关性提供了表面应变场数据。结果表明,纤维沉积模式对缺口敏感性、失效载荷和机理有重大影响,缺口几何形状则次之。单向布局的试样强度最高,但会逐渐失效,而准各向同性试样则会从缺口处突然失效。同心布局可遮挡缺口区域,但由于横向应力的影响,会导致远离缺口的试样过早失效。应力集中因子方法对传统层压板效果良好,但由于局部差异和复杂的相互作用,对三维打印复合材料有一定的局限性。优化纤维沉积,而不是几何形状,是一种很有前途的设计方法。结合单向算法和轮廓算法可以提高性能。不过,还需要利用多尺度建模和局部失效分析进行进一步研究,以充分了解失效机制,并指导三维打印复合材料的最佳缺口设计。随着理解和设计方法的改进,3D 打印有望为结构高效的缺口复合材料部件带来新的可能性。
Highly strain rate sensitive and ductile composite materials combining soft with stiff TPMS polymer-based interpenetrating phases
Singh Agyapal, Al-Ketan Oraib, Karathanasopoulos Nikolaos
doi:10.1016/j.compstruct.2023.117646
将基于 TPMS 聚合物的软硬互穿相组合在一起的高应变速率敏感性和韧性复合材料
The current work investigates the engineering of strain-rate sensitive and ductile composites through the combination of stiff, triply-periodic-minimal-surface (TPMS) with soft, rubber-type material phases. Different interpenetrating phase composite (IPC) designs are considered, with Diamond, Fisher-Koch, and IWP TPMS architectures as reinforcement phase topologies. The loading rate sensitivity of the arising IPCs is evaluated at different strain-rates, revealing an effective composite performance that well separates from the either brittle or substantially low-strength behavior of its constituent materials. Significant strain-rate effects are recorded, which relate to increased stiffness and energy absorption attributes upon substantial ductility, with the actual performance to depend on the underlying reinforcement phase topology. The effective strain-rate IPC constitutive response is well-captured by dedicated, low numerical cost and high accuracy machine learning models, whereas Digital Image Correlation (DIC) and finite element analysis are employed to provide insights in the inner strain and stress fields developed and failure modes observed. Overall, energy absorptions higher than 10 and up to 14 MJ m-3 are reported for strain-rates in the order of 100, furnishing specific energy absorptions (SEA) in the uppermost range of the effective composite material behaviors up to now reported, upon exceptionally high crushing force efficiencies (CFE) at moderate densities.
目前的研究工作是通过将坚硬的三周期最小表面(TPMS)与柔软的橡胶类材料相组合,研究应变速率敏感型韧性复合材料的工程设计。研究考虑了不同的互穿相复合材料(IPC)设计,将金刚石、费希尔-科赫和 IWP TPMS 结构作为增强相拓扑结构。在不同的应变速率下,对所产生的 IPC 的加载速率敏感性进行了评估,结果表明,有效的复合材料性能完全不同于其组成材料的脆性或实质上的低强度行为。研究记录了显著的应变速率效应,这与增加的刚度和能量吸收属性有关,而实际性能则取决于底层增强相拓扑结构。专用、低数值成本和高精度的机器学习模型可以很好地捕捉到有效应变速率 IPC 构成响应,而数字图像相关性(DIC)和有限元分析则用于深入了解内部应变和应力场的发展以及所观察到的失效模式。总体而言,在应变速率为 100 的情况下,能量吸收高于 10 兆焦耳/立方米,最高可达 14 兆焦耳/立方米,在中等密度下具有极高的破碎力效率 (CFE) 时,比能量吸收 (SEA) 达到了目前所报道的有效复合材料行为的最高范围。
A unified hybrid Ritz-SEA acoustic vibration coupling method of a rectangular plate coupled with fast multipole boundary integration
Zhao Yiming, Wang Zhonggang, Yang Zhigang, Qin Bin
doi:10.1016/j.compstruct.2023.117650
与快速多极边界积分相结合的矩形板声学振动耦合统一混合 Ritz-SEA 方法
The Ritz method, based on a segmental strategy, is known for its fast convergence and ability to handle arbitrary boundary conditions while maintaining accuracy comparable to benchmark solutions. It is particularly effective in calculating vibrations in composite laminates, functionally graded plates, and other novel plate types. However, this method faces challenges in accurately calculating the mid-frequency problems that arise between plate structures and acoustic cavities. To fill this gap, this paper proposes a Ritz and statistical energy analysis (Ritz-SEA) hybrid method for calculating rectangular plate acoustic vibration coupling in the mid-frequency range for both deterministic and random loads. This method utilizes the fast multi-pole boundary element integral equation and region segmentation mapping as the governing equation for the coupling boundaries. The power flow equation of the statistical energy analysis (SEA) method is incorporated to solve for the average sound pressure level and sound power level of the coupled acoustic cavity. A method that combines the CHIEF and Burton-Miller methods has been proposed to address the issue of non-unique solutions. Validation and parametric studies are conducted. The results demonstrate that this approach can effectively filter out random fluctuations in mid-frequency domains while exhibiting exceptional stability and precision.
基于分段策略的 Ritz 方法以其收敛速度快、能够处理任意边界条件而著称,同时还能保持与基准解法相当的精度。它在计算复合材料层压板、功能分级板和其他新型板材的振动时尤为有效。然而,这种方法在精确计算板结构和声腔之间产生的中频问题时面临挑战。为了填补这一空白,本文提出了一种里兹和统计能量分析(Ritz-SEA)混合方法,用于计算确定性载荷和随机载荷下矩形板在中频范围内的声学振动耦合。该方法利用快速多极边界元积分方程和区域分割映射作为耦合边界的控制方程。统计能量分析(SEA)方法的功率流方程用于求解耦合声腔的平均声压级和声功率级。还提出了一种结合 CHIEF 和 Burton-Miller 方法的方法,以解决非唯一解的问题。我们进行了验证和参数研究。结果表明,这种方法可以有效过滤中频域的随机波动,同时表现出卓越的稳定性和精确性。
Vibro-acoustic performance of graded piezoelectric metamaterial plates
Schimidt Camila Sanches, de Oliveira Leopoldo Pisanelli Rodrigues, De Marqui Carlos
doi:10.1016/j.compstruct.2023.117656
分级压电超材料板的振动声学性能
This work investigates the vibro-acoustic performance of graded piezoelectric metamaterial plates. The governing equations are presented for an unimorph electromechanically coupled metamaterial plate. A piezoelectric layer with electrodes segmented in a regular lattice is attached over a rectangular, simply-supported panel to realize the electromechanically coupled metamaterial plate, rendering a geometrically periodic structure. The grading is achieved in the electric domain, as each unit cell’s inductive shunt resonant frequency can be tuned independently. We investigate two first-order grading patterns based on linear variations along one and both dimensions of the plate and evaluate their impact on vibration attenuation, sound power, kinetic energy, and acoustic radiation efficiency. The graded metamaterial plates outperform the periodic locally resonant counterparts in vibration and radiated sound power attenuation. Moreover, sound radiation efficiency may increase within the attenuation band for steep grading patterns related to the vibration localization phenomenon. The results show that piezoelectric metamaterial plates with reconfigurable properties are an interesting alternative for enhanced vibro-acoustic performance.
这项研究探讨了分级压电超材料板的振动声学性能。本文给出了单变形机电耦合超材料板的控制方程。为实现机电耦合超材料板,在简单支撑的矩形面板上附着了以规则晶格分割电极的压电层,形成了几何周期性结构。由于每个单元格的电感并联谐振频率可以独立调整,因此可以在电域实现分级。我们研究了基于沿板的一维和两维线性变化的两种一阶分级模式,并评估了它们对振动衰减、声功率、动能和声辐射效率的影响。分级超材料板在振动和辐射声功率衰减方面优于周期性局部谐振板。此外,对于与振动局部化现象有关的陡峭分级模式,声辐射效率可能会在衰减带内提高。研究结果表明,具有可重构特性的压电超材料板是增强振动声学性能的一种有趣的替代方案。
Induction thermography for unidirectional CFRP composites: A novel inspection approach through global current path integration
Kidangan Renil Thomas, Unnikrishnakurup Sreedhar, Krishnamurthy C.V., Balasubramaniam Krishnan
doi:10.1016/j.compstruct.2023.117678
用于单向 CFRP 复合材料的感应热成像技术:通过全局电流路径集成的新型检测方法
In the evolving field of non-destructive testing of composite materials, induction thermography offers significant potential. However, its application to Unidirectional Carbon Fiber Reinforced Polymer (UD CFRP) composites remains challenging due to the unavailability of global current paths. This study introduces a novel methodology to inspect UD CFRP composites using Induction Thermography by incorporating an additional conduction current loop between the composite layers. Initial proof-of-concept experiments were conducted on fiber tow and further validated on laminates. The findings substantiate that the integration of a global current path notably facilitates laminate heating, enhancing the induction thermographic inspection capability. An unexpected discovery in our research is the ability of a circular coil to detect fiber breakage in a laminate that is nearly an order of magnitude wider than the coil diameter, thus demonstrating the approach’s high sensitivity. The practical applicability of the proposed methodology was demonstrated using an external fixture. Moreover, this work proposes an innovative modification to the manufacturing process of non-crimp textiles by incorporating a conductive thread, envisaged to bolster the induction thermographic inspection efficiency further. Numerical modeling, closely aligning with experimental observations, provides a robust theoretical foundation for our work.
在不断发展的复合材料无损检测领域,感应热成像技术具有巨大的潜力。然而,由于无法获得全局电流路径,将其应用于单向碳纤维增强聚合物(UD CFRP)复合材料仍具有挑战性。本研究介绍了一种使用感应热成像技术检测 UD CFRP 复合材料的新方法,即在复合材料层之间增加一个传导电流回路。在纤维丝束上进行了初步概念验证实验,并在层压板上进行了进一步验证。研究结果证明,整合全电流路径可显著促进层压板加热,增强感应热成像检测能力。我们研究中的一个意外发现是,圆形线圈能够检测到比线圈直径宽近一个数量级的层压板中的纤维断裂,从而证明了该方法的高灵敏度。使用外部夹具证明了所建议方法的实际适用性。此外,这项研究还提出了一种创新的方法,即在非卷曲纺织品的制造过程中加入导电线,以进一步提高感应热成像检测的效率。数值建模与实验观察紧密结合,为我们的工作提供了坚实的理论基础。
Impacts of nanofiller shapes on the interface confinement effect in polymer nanocomposites
Wang Guotong, Wang Ruijie, Wang Liya, Wang Chengyuan, Zhang Faling, Wang Ziyu, Tang Chun
doi:10.1016/j.compstruct.2023.117679
纳米填料形状对聚合物纳米复合材料界面约束效应的影响
Shape effect of nanofillers (NFs) on the properties of nanocomposites has attracted considerable attention in recent research. The present study aims to examine how NF shapes influence the confinement effect of polymer-NF interface on the physical properties of nearby polymer (the interphase). Herein molecular dynamics simulations are performed to capture the shift of interphase properties when NFs change from nanosphere to nanocylinder and nanofilm geometry. A stress analysis is then carried out in the interphase to identify a key parameter for characterizing the stress-property coupling and revealing the pathway of the NF shapes to impact the interphase properties. It is shown that the peak hydrostatic stress σ_hyd quantifies the effect of internal stresses on the properties of the interphase. Specifically, the shape transition considered can substantially enhance the peak σ_hyd by flattening the stress space in the interphase without largely affecting the polymer-NF interaction. Increased peak σ_hyd in turn upshifts the interphase properties and thus, leads to the coupling between the NF shapes and interface confinement effect.
纳米填料(NFs)的形状对纳米复合材料性能的影响在最近的研究中引起了广泛关注。本研究旨在探讨 NF 的形状如何影响聚合物-NF 界面对附近聚合物(相间)物理性质的约束效应。本文通过分子动力学模拟来捕捉 NF 从纳米球到纳米圆柱和纳米薄膜几何形状变化时相间特性的变化。然后在相间进行应力分析,以确定表征应力-性能耦合的关键参数,并揭示 NF 形状影响相间性能的途径。结果表明,静水压力峰值 σ_hyd 可以量化内应力对相间特性的影响。具体来说,所考虑的形状转变可通过平整相间层中的应力空间来大幅提高峰值 σ_hyd,而不会在很大程度上影响聚合物-NF 的相互作用。σ_hyd峰值的增加反过来又会提高相间特性,从而导致无纺布形状与界面约束效应之间的耦合。
MOF derived NiFe@C composites with controllable multi-dimensional microstructures for broadband microwave absorption
Liu Bo, Feng Mengfei, Liang Biao, Xiao Junjie, Feng Mengfei, Cheng Hui, Li Yuan, Cheng Yi, Zhang Kaifu
doi:10.1016/j.compositesa.2023.107869
具有可控多维微结构的 MOF 衍生 NiFe@C 复合材料用于宽带微波吸收
Metal-organic framework (MOF) derivatives exhibit great potential as microwave absorbing materials (MAMs) owing to their high porosity, abundant surface sites and tunable constituents. Herein, this paper proposed “Efficient microstructure controllable strategy” for synthesizing thin-thickness broadband MAMs named NiFe@C by regulating its material microstructure. NiFe-MOF-74 precursors were firstly prepared through solvothermal method. By controlling the supersaturation of precursors, three kinds of microstructures were obtained: 3-dimensional lotus-like nanorods self-assembled structure, 1-dimensional nanospheres/nanorods hybrid structure, and 0-dimensional nanospheres structure. Subsequently, NiFe@C derivatives were obtained by pyrolysis, inheriting the microstructures of NiFe-MOF-74. The lotus-like structure of NiFe@C achieves an effective absorption bandwidth (reflection loss < -10 dB) of 5.09 GHz (12.91-18.00 GHz) with thickness of only 1.6 mm, while the nanospheres structure of NiFe@C exhibits the maximum absorptance of 99.96% at 17.12 GHz with thickness of 2.3 mm. This work provides a facile direction for designing thin thickness MAMs with broadband microwave absorption capability.
金属有机框架(MOF)衍生物具有高孔隙率、丰富的表面位点和可调控的成分,因此作为微波吸收材料(MAM)具有巨大的潜力。本文提出了 "高效微结构可控策略",通过调节材料的微结构来合成名为 NiFe@C 的薄厚度宽带微波吸收材料。首先通过溶热法制备了 NiFe-MOF-74 前驱体。通过控制前驱体的过饱和度,获得了三种微观结构:三维莲花状纳米棒自组装结构、一维纳米球/纳米棒混合结构和零维纳米球结构。随后,通过热解得到了 NiFe@C 衍生物,继承了 NiFe-MOF-74 的微观结构。莲花状结构的 NiFe@C 在厚度仅为 1.6 毫米的情况下实现了 5.09 GHz(12.91-18.00 GHz)的有效吸收带宽(反射损耗小于 -10dB),而纳米球结构的 NiFe@C 在厚度为 2.3 毫米的情况下在 17.12 GHz 频率下的最大吸收率为 99.96%。这项工作为设计具有宽带微波吸收能力的薄厚度 MAM 提供了一个便捷的方向。
Mechanical properties and failure mechanisms of all-CFRP corrugated sandwich truncated cone
Li Zhibin, Wang Wenyu, Xue Pengcheng, Wei Xingyu, Xiong Jian
doi:10.1016/j.compositesb.2023.111090
全-CFRP 波纹夹层截顶锥的机械性能和失效机理
Cone-shaped sandwich structures are extensively employed in various fields due to their excellent bearing efficiency and designability. In this work, the design approach and integrated manufacturing method for the carbon fiber reinforced plastic (CFRP) corrugated sandwich truncated cone (CSTC) are proposed to improve the anti-debonding ability and ensure the reliability of the sandwich cone. First, the theoretical model for the stiffness of the CSTC is derived, in which the conservative prediction and the upper limit considering the fiber orientation of the cone are derived. The multiple failure modes of the CSTC under axial compression are theoretically established. Then, the failure mechanism map of the CSTC is established to forecast the possible failure modes. The typical failure modes of local buckling, face fracture, and core buckling are captured by experiments and finite element analysis (FEA). The theoretical model of the stiffness and failure modes is verified by the experiments and FEA. The effect of the semi-vertex angle and circumferential cell number on the failure modes is revealed. Furthermore, a more comprehensive failure mechanism map was generated by altering the geometric parameters of the CSTC. The failure modes of Euler buckling and global buckling are acquired by the comprehensive failure mechanism map and verified by FEA. Finally, the optimum design of the CSTC structure was performed. The results show that the failure mode of face fracture has the best bearing efficiency. This research provides a solid foundation for designing and applying lightweight CSTCs in constructions, such as the adapter of launch vehicles.
锥形夹层结构因其优异的承载效率和可设计性被广泛应用于各个领域。本文提出了碳纤维增强塑料(CFRP)波纹夹层截顶锥体(CSTC)的设计方法和集成制造方法,以提高夹层锥体的抗脱粘能力,确保其可靠性。首先,推导了 CSTC 刚度的理论模型,其中考虑了锥体的纤维取向,得出了保守预测值和上限值。从理论上确定了 CSTC 在轴向压缩下的多种失效模式。然后,建立了 CSTC 的失效机理图,以预测可能的失效模式。通过实验和有限元分析(FEA)捕捉到了局部屈曲、端面断裂和核心屈曲等典型失效模式。实验和有限元分析验证了刚度和失效模式的理论模型。半顶角和圆周单元数对失效模式的影响得到了揭示。此外,还通过改变 CSTC 的几何参数生成了更全面的失效机理图。通过综合失效机理图获得了欧拉屈曲和全局屈曲的失效模式,并通过有限元分析进行了验证。最后,对 CSTC 结构进行了优化设计。结果表明,面断裂失效模式具有最佳承载效率。这项研究为轻质 CSTC 在运载火箭适配器等结构中的设计和应用奠定了坚实的基础。
High thermal conductive polyurethane composite films with a three-dimensional boron nitride network in-situ constructed by multi-folding and multi-laminating
Yang Lide, Huang Rutao, Yuan Jianmin, Zhang Pingan, Deng Jianru, Li Qiang
doi:10.1016/j.compscitech.2023.110326
通过多重折叠和多重层压在原位构建具有三维氮化硼网络的高导热聚氨酯复合薄膜
Based on the chemical modifications of the few-layer boron nitride nanosheets (BNNSs) prepared by ball milling, several BNNS/polyurethane (PU) composite films (non-laminated films) were prepared by solution blending. It showed that the modified BNNSs (M-BNNSs) in PU matrices assembled into boron nitride (BN) micro-flakes and mildly orientated along the film planes. Then, an approach of multi-folding and multi-laminating further promoted the orientation, stacking and connection of BN micro-flakes, by which a three-dimensional (3D) BN network composed of lamellar BN skeleton and a small number of BN linkers was in-situ constructed in the PU composite films (laminated films). For the existence of a continuous heat conductive channel based on the 3D BN network, the thermal conductivities (TCs) of the laminated films were obviously enhanced compared to the corresponding non-laminated films. The incorporation of M-BNNSs further improved the electrical insulation of the laminated films. When the M-BNNS content was 50 wt%, the in-plane TC of the laminated film reached 23.80 W/m·K. The laminated film with M-BNNS content of 30 wt% showed high TC, good flexibility, and outstanding electrical insulation, who is a promising candidate for the flexible thermal management materials.
在对球磨法制备的几层氮化硼纳米片(BNNSs)进行化学修饰的基础上,通过溶液混合法制备了几种氮化硼纳米片/聚氨酯(PU)复合膜(非层压膜)。研究表明,聚氨酯基质中的改性 BNNSs(M-BNNSs)组装成了氮化硼(BN)微片,并沿薄膜平面温和取向。然后,多重折叠和多重层压的方法进一步促进了氮化硼微薄片的取向、堆叠和连接,从而在聚氨酯复合薄膜(层压薄膜)中原位构建了由片状氮化硼骨架和少量氮化硼连接体组成的三维(3D)氮化硼网络。由于基于三维 BN 网络的连续导热通道的存在,与相应的非层压薄膜相比,层压薄膜的导热系数(TCs)明显提高。M-BNNS 的加入进一步提高了层压薄膜的电绝缘性。当 M-BNNS 含量为 50 wt% 时,层压薄膜的面内 TC 达到 23.80 W/m-K。M-BNNS 含量为 30 wt% 的层压薄膜具有较高的 TC 值、良好的柔韧性和出色的电绝缘性能,是柔性热管理材料的理想候选材料。