今日更新：Composite Structures 5 篇，Composites Part A: Applied Science and Manufacturing 1 篇，Composites Part B: Engineering 1 篇Composite StructuresAgglomeration and interphase-influenced effective elastic properties of Metal/Graphene nanocomposites: A developed mean-field modelMojtaba Mazaheri, Javad Payandehpeyman, Mahdi Hedayatiandoi:10.1016/j.compstruct.2023.117762金属/石墨烯纳米复合材料的团聚和相间影响的有效弹性特性：开发的均场模型The strength of metallic nanocomposites structures can be greatly improved by adding nanofillers to the matrix. However, there is a discrepancy between the conventional theories and the experimental evidence on the effect of nanofiller loading on the strength of the nanocomposite. The conventional theories predict that the strength increases with the nanofiller loading, but the experimental evidence shows that there is an optimal nanofiller loading beyond which the strength does not improve much. This discrepancy, especially at high filler loadings, is due to the neglect of the agglomeration and the interphase region formation in the composite structure modeling. In this paper, we propose a new micromechanical model based on mean-field theory to examine how the agglomeration and the interphase region influence the elastic modulus of metal/graphene nanocomposites (MGNs). We also explore how other factors, such as interphase region thickness and strength, graphene size, and metallic matrix elastic modulus, influence the elastic modulus of MGNs. We present a mathematical model that describes how the thickness and modulus of the interphase layer of graphene nanoplatelets change due to agglomeration. This model allows us to reproduce the parabolic behavior of the elastic modulus of the composite, which is consistent with the experimental results.在基体中添加纳米填料可以大大提高金属纳米复合材料结构的强度。然而，在纳米填料的添加量对纳米复合材料强度的影响方面，传统理论与实验证据之间存在差异。传统理论预测强度会随着纳米填料含量的增加而增加，但实验证据表明，存在一个最佳的纳米填料含量，超过这个含量，强度不会有太大改善。这种差异，尤其是在高填充量时，是由于在复合材料结构建模中忽略了团聚和相间区域的形成。在本文中，我们提出了一种基于均场理论的新微机械模型，以研究团聚和相间区如何影响金属/石墨烯纳米复合材料（MGNs）的弹性模量。我们还探讨了相间区厚度和强度、石墨烯尺寸和金属基体弹性模量等其他因素如何影响 MGN 的弹性模量。我们提出了一个数学模型，用于描述石墨烯纳米片相间层的厚度和模量如何因团聚而发生变化。通过该模型，我们可以再现复合材料弹性模量的抛物线行为，这与实验结果是一致的。Continuous fiber reinforced meta-composites with tailorable Poisson’s ratio and effective elastic modulus: Design and experimentGuixing Li, Yuan Chen, Guangkai Weidoi:10.1016/j.compstruct.2023.117768具有可定制泊松比和有效弹性模量的连续纤维增强元复合材料：设计与实验Auxetic metamaterials, i.e., with negative Poisson’s ratio are attracting increasing attention. This study develops a novel method to design and investigate continuous fiber-reinforced meta-composites with tailorable negative Poisson’s ratio and effective elastic modulus. First, the design scheme based on parametric level set method, is proposed by combining fast marching method, filtering technology and matrix rotation for attaining the two-dimensional isotropic composites. A novel objective function considering both negative Poisson’s ratio and effective elastic modulus is introduced and the result demonstrate that it is effective to not only accelerate the numerical convergence but also achieve a larger negative Poisson’s ratio when compared with that using the currently-used objective function. By tailoring a weight ratio for balancing the negative Poisson’s ratio and effective elastic modulus, a general contradictive trend was captured. Experimentally, the specimens are accordingly fabricated via 3D printing. Then, the axial compression tests are performed with the aid of digital image correlation technology to characterize the deformation behaviors and evaluate the mechanical properties of the designed meta-composites. Experimental results show that, as the weight ratio increases from 0.02 to 1.57, the effective elastic modulus increases from 180.5 MPa to 310.3 MPa (enhanced by 71.9%) while the negative Poisson’s ratio decreases from −0.41 to −0.036 (reduced by 91.4%), proving the effectiveness of the design method. The design methods and experimental results can provide effective approaches and important information for designing novel continuous fiber reinforced meta-composites with tailorable mechanical performance.具有负泊松比的超材料正受到越来越多的关注。本研究开发了一种新方法，用于设计和研究具有可定制负泊松比和有效弹性模量的连续纤维增强超材料。首先，结合快速行进法、过滤技术和矩阵旋转，提出了基于参数水平集法的设计方案，以获得二维各向同性复合材料。引入了同时考虑负泊松比和有效弹性模量的新目标函数，结果表明，与目前使用的目标函数相比，它不仅能有效加快数值收敛速度，还能获得更大的负泊松比。通过调整权重比来平衡负泊松比和有效弹性模量，可以捕捉到一个普遍的矛盾趋势。实验中，试样是通过三维打印制作的。然后，借助数字图像相关技术进行轴向压缩试验，以表征变形行为并评估所设计元复合材料的力学性能。实验结果表明，随着重量比从 0.02 增加到 1.57，有效弹性模量从 180.5 兆帕增加到 310.3 兆帕，提高了 71.9%，负泊松比从-0.41 下降到-0.036，降低了 91.4%，证明了设计方法的有效性。设计方法和实验结果可为设计具有可定制力学性能的新型连续纤维增强元复合材料提供有效方法和重要信息。Femtosecond laser drill high modulus CFRP multidirectional laminates with a segmented arc-based concentric scanning methodChunyang Zhao, Zhenhua Ma, Jiayan Sun, Likuan Zhudoi:10.1016/j.compstruct.2023.117769利用基于分段圆弧的同心扫描方法，用飞秒激光钻削高模量 CFRP 多向层压板High modulus carbon fiber reinforced plastic multidirectional laminates (HM-CFRP-MDL) are widely employed in the aerospace industry as crucial structural materials for satellites, rockets, and aircraft. However, it is difficult for the femtosecond laser to drill holes on HM-CFRP-MDL with the traditional concentric scanning method (CSM). To improve drilling quality and precision, this study proposes a segmented arc-based concentric scanning method (SAB-CSM) and investigates the interaction mechanisms between femtosecond lasers and CFRP. By adopting the proposed scanning method with optimized parameters, the overall average HAZ width can be decreased to 10 μm in different regions on the surface of the drilled hole, the hole taper can be reduced significantly, and the consistency across different layers can be improved. Compared to CSM, the HAZ width can be decreased by 40.8% (12.597μm to 7.464μm) and 50.3% (15.585μm to 7.748μm) in the regions where the angles between fiber direction and scanning direction are 45° and 90° respectively, and the taper can be reduced by 34.5% (0.084 to 0.055). Moreover, the SAB-CSM approach effectively decreases quality discrepancies between different layers, and substantially reduces those defects which results in smooth and uniform hole walls, facilitating synergistic removal of multidirectional carbon fibers and resin matrix.高模量碳纤维增强塑料多向层压板（HM-CFRP-MDL）作为卫星、火箭和飞机的重要结构材料被广泛应用于航空航天领域。然而，传统的同心扫描法（CSM）很难在 HM-CFRP-MDL 上用飞秒激光钻孔。为了提高钻孔质量和精度，本研究提出了一种基于分段圆弧的同心扫描方法（SAB-CSM），并研究了飞秒激光与 CFRP 之间的相互作用机制。通过采用建议的扫描方法和优化参数，钻孔表面不同区域的整体平均 HAZ 宽度可降至 10 μm，钻孔锥度可显著减小，不同层间的一致性可得到改善。与 CSM 相比，HAZ 宽度可减少 40.8%（12.597μm 至 7.464μm），在纤维方向与扫描方向的夹角分别为 45° 和 90° 的区域，HAZ 宽度可减少 50.3%（15.585μm 至 7.748μm），锥度可减少 34.5%（0.084 至 0.055）。此外，SAB-CSM 方法还能有效减少不同层之间的质量差异，并大幅减少缺陷，从而获得光滑均匀的孔壁，促进多向碳纤维和树脂基体的协同去除。Conductive nanoparticle-embedded carbon composite bipolar plates for vanadium redox flow batteriesJaeheon Choe, Jun Woo Limdoi:10.1016/j.compstruct.2023.117770用于钒氧化还原液流电池的导电纳米粒子嵌入碳复合双极板Electrochemical reduction and oxidation reactions of vanadium ions can enable efficient power management by a secondary battery, such as a vanadium redox flow battery (VRFB). To increase the energy efficiency of a VRFB system, the electrical resistance of the cell component, such as a bipolar plate, should be reduced. In this study, particles of polyaniline (PANI), a conductive polymer, were embedded in a carbon/epoxy composite by spraying on the prepreg surface to increase the electrical conductivity of the bipolar plate. The effect of the PANI particles on the electrical and mechanical properties was investigated. Furthermore, the optimum PANI content of 3 wt.% achieved an area-specific resistance of 16.7 mΩ·cm2, 55.2% lower than that of the neat specimen. The tensile strength was improved to 586 MPa, a 13.8% increase compared with the neat specimen. Finally, the cell performance of the fabricated bipolar plate was verified via permeability and single-cell charge/discharge tests.钒离子的电化学还原和氧化反应可使钒氧化还原液流电池（VRFB）等二次电池实现高效的电源管理。为了提高钒氧化还原液流电池系统的能量效率，应降低电池组件（如双极板）的电阻。在本研究中，通过在预浸料表面喷涂的方式，将导电聚合物聚苯胺（PANI）颗粒嵌入碳/环氧树脂复合材料中，以提高双极板的导电性。研究了 PANI 粒子对电气和机械性能的影响。此外，3 wt.% 的最佳 PANI 含量可实现 16.7 mΩ-cm2 的面积特定电阻，比纯试样低 55.2%。拉伸强度提高到 586 兆帕，比纯试样提高了 13.8%。最后，通过渗透性和单电池充放电测试验证了制作的双极板的电池性能。Vibration-based prediction of residual fatigue life for composite laminates through frequency measurementsZhihong Liang, Karthik Ram Ramakrishnan, Ching-Tai NG, Zhifang Zhang, Jiyang Fudoi:10.1016/j.compstruct.2023.117771通过频率测量以振动为基础预测复合材料层压板的残余疲劳寿命Fiber reinforced polymer (FRP) structures may experience cumulative fatigue damage during their service life which can lead to structural failure. This paper focuses on predicting the residual fatigue life of FRP structures using vibration parameters. The relationship between residual fatigue life and natural frequencies is examined through modal testing and fatigue measurements on FRP beam specimens. Two prediction methods; semi-empirical models and machine learning (ML) algorithms, are utilized. The semi-empirical models are derived from existing “residual stiffness” models based on the relationship between bending stiffness and flexural frequencies. ML algorithms Support Vector Machine (SVM) and Artificial Neural Network (ANN), are developed for fatigue life prediction. Experimental validation is performed using measured frequencies during fatigue testing of FRP beams. The ML algorithms can use multimode frequencies unlike single mode of semi-empirical models. The verification results show that the ML algorithms can be used to predict the residual fatigue life with the selection of the appropriate mode of frequency. The results show that ML algorithms outperform single-mode frequency inputs, and the use of higher modes of measured frequencies improves the precision of fatigue life prediction. An inverse algorithm based on SVM exhibits higher prediction accuracy and stability, even with limited training samples.纤维增强聚合物（FRP）结构在其使用寿命期间可能会经历累积性疲劳损伤，从而导致结构失效。本文的重点是利用振动参数预测 FRP 结构的残余疲劳寿命。通过对玻璃钢梁试样进行模态测试和疲劳测量，研究了残余疲劳寿命与固有频率之间的关系。采用了两种预测方法：半经验模型和机器学习（ML）算法。半经验模型是根据弯曲刚度和挠曲频率之间的关系，从现有的 "残余刚度 "模型中推导出来的。为疲劳寿命预测开发了支持向量机（SVM）和人工神经网络（ANN）等 ML 算法。在对玻璃钢梁进行疲劳测试时，使用测得的频率进行了实验验证。与半经验模型的单一模式不同，ML 算法可以使用多模式频率。验证结果表明，通过选择适当的频率模式，ML 算法可用于预测残余疲劳寿命。结果表明，ML 算法优于单模式频率输入，使用较高的测量频率模式可提高疲劳寿命预测的精度。基于 SVM 的反算法即使在训练样本有限的情况下也能表现出更高的预测精度和稳定性。Composites Part A: Applied Science and ManufacturingSignificantly Enhanced Tribological Properties of PTFE/PEEK Fabric Composites by Macroporous Metal−Organic Frameworks with Solid–Liquid Synergistic LubricationMingkun Xu, Jing Zhang, Song Li, Tingmei Wang, Qihua Wang, Liming Tao, Peng Liudoi:10.1016/j.compositesa.2023.107935 大孔金属有机框架固液协同润滑显著增强 PTFE/PEEK 织物复合材料的摩擦学性能In this work, a macroporous oil-containing metal-organic framework material (CuBTCO) was prepared by a solvothermal method and vacuum impregnation. The tribological behaviors of PTFE/PEEK fabric composites (PFC) filled with CuBTCO were evaluated by the pin-on-disk tribometer under different loads. The coefficient of friction and mass wear rate of PFC containing 6 wt% CuBTCO (PFC-CuBTCO-6%) were 0.017 and 1.1×10-9 g/(Nm), respectively, which were reduced by 63.8% and 76.3% in comparison to PFC containing 6 wt% CuBTC under the same conditions. The excellent tribological properties of PFC-CuBTCO-6% are attributed to the solid–liquid synergistic lubrication between the adsorption film formed by the oleylamine released from CuBTCO and the PTFE-based transfer film. This work provides a novel approach for the structural design of solid–liquid synergistic lubrication of fabric liner composites.本研究采用溶热法和真空浸渍法制备了一种大孔含油金属有机框架材料（CuBTCO）。在不同载荷下，采用针盘摩擦磨损试验仪对填充了 CuBTCO 的 PTFE/PEEK 纤维复合材料（PFC）的摩擦学行为进行了评估。在相同条件下，含 6 wt% CuBTCO 的 PFC（PFC-CuBTCO-6%）的摩擦系数和质量磨损率分别为 0.017 和 1.1×10-9 g/(Nm)，与含 6 wt% CuBTC 的 PFC 相比分别降低了 63.8% 和 76.3%。PFC-CuBTCO-6% 的优异摩擦学特性归功于 CuBTCO 释放的油胺形成的吸附膜与基于 PTFE 的转移膜之间的固液协同润滑作用。这项研究为织物衬垫复合材料的固液协同润滑结构设计提供了一种新方法。Composites Part B: EngineeringMechanism-based damage and failure of fused filament fabrication componentsIván Rivet, Narges Dialami, Miguel Cervera, Michele Chiumentidoi:10.1016/j.compositesb.2023.111119基于机理的熔融长丝制造组件的损坏和失效Fused Filament Fabrication (FFF) is a polymer-based Additive Manufacturing (AM) technology that produces complex layered components. The characterization of the inherited orthotropic properties of FFF components and their failure analysis is a challenging endeavor. In this paper, the failure mechanics of FFF parts are studied via a Mechanism-Based (MB) damage material model. A MB damage criterion is developed by considering that the damage is driven by different failure modes identified according to the printing pattern. The developed criterion is compared to the Tsai–Wu (TW) criterion, which is commonly used for orthotropic materials with different strengths in tension and compression. Also, a MB cracking model that incorporates the orthotropic brittleness of FFF components is developed. The application of this cracking model requires solely two parameters to be defined. Numerical predictions of the cracking of two different experimental tests illustrate the similarities and the differences between the MB and TW damage criteria. The results demonstrate that the MB damage criterion can accurately match the experimental results, while the TW criterion fails to describe correctly the failure modes in complex 3D stress states.熔融长丝制造（FFF）是一种基于聚合物的增材制造（AM）技术，可生产复杂的分层部件。表征 FFF 部件的继承正交特性并对其进行失效分析是一项具有挑战性的工作。本文通过基于机理（MB）的损伤材料模型对 FFF 零件的失效力学进行了研究。考虑到破坏是由根据印刷模式确定的不同破坏模式驱动的，因此制定了 MB 破坏准则。所开发的准则与蔡武（TW）准则进行了比较，后者通常用于具有不同拉伸和压缩强度的各向同性材料。此外，还开发了一种包含 FFF 组件正交脆性的 MB 裂纹模型。应用该开裂模型只需定义两个参数。对两种不同实验测试的开裂情况进行的数值预测说明了 MB 和 TW 损坏标准之间的异同。结果表明，MB 损伤准则能够准确匹配实验结果，而 TW 准则则无法 正确描述复杂三维应力状态下的破坏模式。来源：复合材料力学仿真Composites FEM
