今日更新:Composite Structures 2 篇,Composites Part A: Applied Science and Manufacturing 2 篇,Composites Part B: Engineering 3 篇,Composites Science and Technology 3 篇
Failures of laminates under nonpenetrative impacts
Junchen Zhou, Zheng-Ming Huang
doi:10.1016/j.compstruct.2024.118096
非穿透性冲击下层压板的失效
Various failures of laminates under low-velocity impacts without penetration are simulated systematically with a limited number of inputs, all measurable following existing standards without any data calibration. No iteration is required to determine any of the failures investigated in this work. Any two adjacent lamina (primary) layers are inserted with a matrix (secondary) layer, whose stresses are modified through two modification coefficients (MCs). The MCs are determined through peak loads of double cantilever beam and end-notched flexure tests on unidirectional laminates, and their weak sensitivity to sample dimensions is shown. Delamination is reproduced by deleting failed secondary-layer elements. The homogenized stresses of fiber and matrix obtained by Bridging Model are converted into true values through the author’s true stress theory to estimate constituent-induced intralaminar failures, such as fiber breakage, matrix crack and interface debonding, against the monolithic fiber or matrix strengths measured independently. Primary- layer elements attaining a fatal failure (fiber breakage or matrix crack accompanied with a critical strain condition) are deleted before an impact termination corresponding to separation of the impactor from target. The predicted delamination areas and impact force, displacement and energy histories for the laminates of three lamination angles under different impact energies agree well with our measured counterparts, validating the efficiency of the simulation.
本文系统地模拟了层压板在低速冲击下无穿透的各种失效,输入数量有限,所有失效均可按照现有标准测量,无需任何数据校准。不需要迭代来确定本工作中调查的任何故障。任意两个相邻的层(主)层插入基质(次)层,基质(次)层的应力通过两个修正系数(mc)进行修正。通过双悬臂梁峰值荷载和单向层合板端缺口挠曲试验确定了MCs,表明MCs对试样尺寸的敏感性较弱。通过删除失败的第二层元素来重现分层。通过作者提出的真应力理论,将桥接模型得到的纤维和基体的均质应力转换为真值,根据独立测量的整体纤维或基体强度,估计由成分引起的纤维断裂、基体裂纹和界面脱粘等层内破坏。达到致命破坏(纤维断裂或伴随临界应变条件的基体裂纹)的初级层单元在撞击终止前被删除,对应于撞击器与目标的分离。在不同冲击能量下,三种层合角度层合材料的分层面积、冲击力、位移和能量历史与实测数据吻合较好,验证了仿真的有效性。
Verification and Validation of finite element models for laminated timber structures using solid, solid-beam and solid-shell approaches
Jeanne Paroissien, Marc Oudjene, Pascal Lardeur
doi:10.1016/j.compstruct.2024.118083
采用实心、实心梁和实心壳方法的层合木结构有限元模型的验证与验证
This paper presents a numerical approach to assess efficiently the vibration performance of adhesive-free engineered wood products assembled through compressed wood dowels. Predictive finite element models are obtained by applying the Verification and Validation methodology. The models are first developed using solid elements. Then, solid-beam and solid-shell approaches based on standard solid elements are developed with first-order or higher-order theories. Beam or shell kinematic assumptions are applied throughout the cross-section of the dowels and through the thickness of the layers. From a numerical point of view, a modification of the system of algebraic equations, based on the concept of independent and dependent nodes, is developed. Dependent nodes are eliminated, resulting in a significant reduction in the number of degrees of freedom and floating-point operations. The methodology is evaluated for the calculation of frequencies and mode shapes of adhesive-free laminated timber beams and timber panels with a mix of solid elements, solid-shell and solid-beam approaches. The study highlights the efficiency of the proposed modelling approach in terms of quality of results and model size reduction.
本文提出了一种通过压缩木钉装配无胶粘剂工程木制品的振动性能的数值评估方法。应用验证和验证方法得到预测有限元模型。这些模型首先是使用实体元素开发的。然后,基于一阶或高阶理论,发展了基于标准实体单元的固体梁和固体壳方法。梁或壳的运动学假设应用于整个销子的横截面和层的厚度。从数值角度出发,基于独立节点和相依节点的概念,对代数方程组进行了改进。消除了相关节点,从而大大减少了自由度和浮点操作的数量。该方法用于计算无胶粘剂层压木梁和木板的频率和模态振型,采用固体单元、固体壳和固体梁的混合方法。该研究强调了所提出的建模方法在结果质量和模型尺寸减小方面的效率。
A new method for obtaining the in situ interfacial shear strength of the 3D woven composite
Qingsong Zong, Jinzhao Huang, Ruijian Sun, Junfeng Ding, Tao Zheng, Kai Huang, Licheng Guo
doi:10.1016/j.compositesa.2024.108215
三维编织复合材料原位界面抗剪强度的一种新方法
The interfacial strengths have significant effects on the accuracy of numerical simulations for the 3D woven composite (3DWC). However, obtaining the in situ interfacial strengths of the 3DWC currently presents substantial challenges. Furthermore, it remains questionable whether the interlaminar strength of laminate composites can represent the interfacial strength of the 3DWC. This paper proposes an in situ experiment-simulation (ISES) method to determine the shear strength of the interface within the 3DWC. For this purpose, several novel off-axis tensile specimens were designed with a simplified and continuous interface structure. A corresponding full-scale finite element (FE) model based on the mesoscale structure of the specimen was established, employing the cohesive zone model to describe the interface mechanical behavior. The in situ interfacial shear strength of the 3DWC was then obtained using the proposed ISES method.
界面强度对三维编织复合材料(3DWC)的数值模拟精度有重要影响。然而,获得3DWC的原位界面强度目前面临着巨大的挑战。此外,层压复合材料的层间强度能否代表3DWC的界面强度还有待商榷。本文提出了一种原位实验模拟(ISES)方法来确定3DWC内界面的抗剪强度。为此,设计了几种具有简化连续界面结构的新型离轴拉伸试件。基于试件的细观结构,建立了相应的全尺寸有限元模型,采用内聚区模型描述界面力学行为。然后使用提出的ISES方法获得了3DWC的原位界面抗剪强度。
Correlation between interfacial bond strength and degree of healing in overprinting PAEK on CF/PAEK composites
Nan Yi, Yu Chen, Jiajia Shen, Richard Davies, Oana Ghita
doi:10.1016/j.compositesa.2024.108217
CF/PAEK复合材料套印PAEK时界面结合强度与愈合程度的关系
Overprinting is a new emerging hybrid manufacturing process that combines composite manufacturing and additive manufacturing, offering the dual advantages of cost-effectiveness and design freedom. This study presents the first endeavour of overprinting high temperature polymers. The joint strength was measured by the rib-on-plate test. A modified non-isothermal healing model was developed to predict the interfacial bond strength, based on thermal history at the interface during overprinting. The model captures how crystallisation impedes interfacial diffusion. The degree of intimate contact was employed to evaluate the true interfacial strength. A positive linear correlation was identified between the interfacial bond strength and the final degree of healing. This study reveals the critical effect of crystallisation on diffusion when the processing temperature is above the glass transition temperature, offering a more comprehensive understanding of the bonding mechanism of high temperature semi-crystalline polymers.
套印是一种新兴的混合制造工艺,它结合了复合材料制造和增材制造,具有成本效益和设计自由的双重优势。本研究是高温聚合物套印的首次尝试。采用肋板试验测量接头强度。建立了一种改进的非等温愈合模型,基于叠印过程中界面的热历史来预测界面结合强度。该模型捕捉到了结晶如何阻碍界面扩散。用亲密接触度来评价界面的真实强度。界面结合强度与最终愈合程度呈线性正相关关系。本研究揭示了当加工温度高于玻璃化转变温度时结晶对扩散的关键影响,为更全面地理解高温半晶聚合物的键合机制提供了依据。
Room-temperature plasticity of metallic glass composites: A review
Quan Dong, Jun Tan, Caiju Li, Baran Sarac, Jürgen Eckert
doi:10.1016/j.compositesb.2024.111453
金属玻璃复合材料的室温塑性研究进展
The remarkable mechanical, chemical, and physical characteristics exhibited by metallic glasses (MGs), arising from their disordered atomic arrangement, present substantial application prospects in the aerospace industry, consumer electronics, biomedical implants and devices, sporting goods, etc. However, the brittleness introduced by highly localized shear bands poses a limitation to broader applications. A promising approach to overcome this limitation involves the development of metallic glass composites (MGCs) via introducing a second phase (or multiple phases) to impede shear band propagation, effectively enhancing MGs' plasticity. This review aims to provide a comprehensive overview of the advancements in methods and mechanisms for improving the plasticity of MGCs. It is divided into two main sections: one detailing the impact of in-situ second phases, such as glassy, quasi-crystal, and crystalline phases (nano- and micro-particles, dendrites, B2 phases, ceramic phases, etc.), on the plasticity of MGCs at different scales. The other section explores the influence of ex-situ second phases on the plasticity of MGCs, encompassing particles, fibers, interpenetrating phases, as well as laminated structures like nano-laminated architecture, coatings, and shrink-fit metal sleeves. Additionally, the review outlines challenges and future prospects in the quest for high plasticity MGCs at room temperature.
金属玻璃由于其无序的原子排列而表现出非凡的机械、化学和物理特性,在航空航天工业、消费电子、生物医学植入物和设备、体育用品等方面具有巨大的应用前景。然而,高度局部化剪切带带来的脆性限制了其更广泛的应用。克服这一限制的一个有希望的方法是通过引入第二相(或多相)来阻止剪切带传播,从而有效提高金属玻璃复合材料(MGCs)的塑性。本文综述了提高MGCs塑性的方法和机制的研究进展。它分为两个主要部分:一部分详细介绍了原位第二相,如玻璃相、准晶相和结晶相(纳米和微粒、枝晶、B2相、陶瓷相等)对不同尺度MGCs塑性的影响。另一部分探讨了非原位第二相对MGCs塑性的影响,包括颗粒、纤维、互穿相以及层压结构,如纳米层压结构、涂层和收缩金属套管。此外,综述概述了在室温下追求高塑性MGCs的挑战和未来前景。
Fatigue response of multiscale extrusion-based additively manufactured acrylonitrile butadiene styrene-graphene nanoplatelets composites
Soran Hassanifard, Kamran Behdinan
doi:10.1016/j.compositesb.2024.111464
多尺度挤压增材制备丙烯腈-丁二烯-石墨烯纳米片复合材料的疲劳响应
This study investigates the effect of varying concentrations of graphene nanoplatelets (GNPs) on the mechanical and fatigue characteristics of acrylonitrile butadiene styrene (ABS)/GNPs nanocomposites, both in filament form and as 3D-printed parts with different raster orientations. Quasi-static and cyclic loading tests were performed on specimens containing 0.1 wt.%, 0.5 wt.%, 1.0 wt.%, and 2.0 wt.% GNPs. The results indicated that the addition of 0.1 wt.% GNPs to the ABS polymer matrix increased the ultimate tensile strength (UTS) of the filament by 18%. Addition of 1.0 wt.% and 2.0 wt.% GNPs to the matrix improved the Young's modulus of the filament by up to about 35% but did not enhance the UTS. The filament containing 0.5 wt.% GNPs demonstrated the highest fatigue life, even higher than that of the standard samples fabricated through injection molding technique. This was due to its high static strength, Young's modulus, and ductility. However, when the ABS/GNPs nanocomposites were 3D-printed, the addition of GNPs had no major impact on their fatigue life, especially in the higher load levels. Inadequate adhesion and reduced interlayer bonding strength resulted in a detrimental impact on fatigue life of 3D-printed objects. The extrudate-swell phenomenon seems to significantly affect this reduction in fatigue life. To address this, larger nozzle diameter (0.6 mm) was used in fabricating 3D-printed samples. Results indicated that samples with less distortion and smaller extrudate-swell had higher fatigue life. It highlights the importance of considering GNP concentration and printing parameters for optimal fatigue properties in ABS/GNPs composites.
本研究研究了不同浓度的石墨烯纳米片(GNPs)对丙烯腈-丁二烯-苯乙烯(ABS)/GNPs纳米复合材料的机械和疲劳特性的影响,包括长丝形式和具有不同光栅取向的3d打印部件。准静态和循环加载试验对含有0.1 wt.%、0.5 wt.%、1.0 wt.%和2.0 wt.% GNPs的试样进行。结果表明,在ABS聚合物基体中添加0.1 wt.%的GNPs可使长丝的极限拉伸强度提高18%。在基体中加入1.0 wt.%和2.0 wt.%的GNPs可使长丝的杨氏模量提高约35%,但没有提高UTS。含有0.5 wt.% GNPs的长丝显示出最高的疲劳寿命,甚至高于通过注射成型技术制造的标准样品。这是由于其高静态强度,杨氏模量和延展性。然而,当ABS/GNPs纳米复合材料进行3d打印时,GNPs的添加对其疲劳寿命没有重大影响,特别是在更高的载荷水平下。粘附力不足,层间结合强度降低,对3d打印物体的疲劳寿命产生不利影响。挤压膨胀现象似乎对疲劳寿命的降低有显著影响。为了解决这个问题,在制造3d打印样品时使用了更大直径(0.6 mm)的喷嘴。结果表明,变形小、挤压膨胀小的试样具有较高的疲劳寿命。它强调了考虑GNP浓度和打印参数对ABS/GNPs复合材料最佳疲劳性能的重要性。
Silk-inspired architectured filament with enhanced stiffness and toughness for fused deposition modelling (FDM)
Li Liang, Filippo Berto, Chao Gao
doi:10.1016/j.compositesb.2024.111474
丝质启发的结构长丝,具有增强的刚度和韧性,用于熔融沉积建模(FDM)
Architectured materials, those capable of manipulating the spatial configurations of two or more material phases, have recently gained substantial attention, primarily due to their unprecedented material properties (e.g., exceptional strength-to-weight ratio and intriguing negative Poisson's ratio). Most architectured materials draw inspiration from the microstructure of natural solutions. One of fascinating examples are spider silk and cocoon silk. Their multimaterial core-shell fibrous structure exhibits remarkable mechanical properties—high stiffness, strength, and toughness. In this study, silk-inspired dual-phase Core-Shell Architectured Filament (CSAF), which combines a rigid Polylactic Acid (PLA) core with a soft Thermoplastic Polyurethane (TPU) shell, was developed as feedstock for additive manufacturing. The mechanical testing of dual-phase CASF printed samples reveal intriguing results. Notably, the optimized CASF in this study, whose volume fraction of rigid core was set as 52%, was observed a substantial improvement of the printed specimens in initial stiffness and energy absorption capacity—up to a remarkable 14-fold increase in initial stiffness and a ∼9% enhancement in energy absorption when compared to the pure TPU filament. To gain a deeper understanding of the synergistic effects arising from geometrical and material configurations on the structure’s damage mechanism, a theoretical model of this core-shell structure was developed. Computational models have been built to validate theoretical model, and the results from finite element analysis are in excellent agreement with experimental results. These discoveries offer valuable insights to enhance mechanical performance of the feedstock for additive manufacturing.
建筑材料,那些能够操纵两个或多个材料相的空间结构的材料,最近获得了大量的关注,主要是由于它们前所未有的材料特性(例如,特殊的强度重量比和有趣的负泊松比)。大多数建筑材料从自然溶液的微观结构中汲取灵感。其中一个有趣的例子是蜘蛛丝和蚕丝。它们的多材料核壳纤维结构具有显著的机械性能——高刚度、高强度和高韧性。在这项研究中,丝绸启发的双相核-壳结构长丝(CSAF),结合了刚性聚乳酸(PLA)芯和柔软的热塑性聚氨酯(TPU)壳,被开发作为增材制造的原料。双相CASF打印样品的力学测试揭示了有趣的结果。值得注意的是,本研究中优化的CASF,刚性芯的体积分数设置为52%,与纯TPU长丝相比,打印样品的初始刚度和能量吸收能力有了显著提高,初始刚度提高了14倍,能量吸收能力提高了9%。为了更深入地了解几何构型和材料构型对结构损伤机理的协同作用,建立了这种核壳结构的理论模型。建立了计算模型对理论模型进行了验证,有限元分析结果与实验结果吻合良好。这些发现为提高增材制造原料的机械性能提供了有价值的见解。
Automatic reconstruction of closely packed fabric composite RVEs using yarn-level micro-CT images processed by convolutional neural networks (CNNs) and based on physical characteristics
Chongrui Tang, Jianchao Zou, Yifeng Xiong, Biao Liang, Weizhao Zhang
doi:10.1016/j.compscitech.2024.110616
基于物理特征的纱线级微ct图像卷积神经网络(cnn)自动重建紧密堆积织物复合材料RVEs
Micro-CT scanning is an advanced technique to reconstruct inner architectures for RVEs of fabric composites. Currently, however, there exist few automatic approaches to separate closely packed yarns in the micro-CT images with economical resolution that can only identify yarns but not individual fibers. To tackle this issue, an innovative method has been developed in this work to identify cross-section area of the yarns via deep-learning-based image segmentation, and then reconstruct 3D geometry model of the composites containing local fiber orientations. The image segmentation was achieved through semantic segmentation by U-Net with validation accuracy of 87% counted by mIOU and object detection by YOLO v8 with validation accuracy of 99.5% counted by mAP50. Micro-CT slices with different morphological characteristics were divided into three groups via a ResNet50-based image classification network and selected in ratio to form the training datasets for U-Net and YOLO v8 with high representativity and efficiency. Extraction of individual cross-sections of weft and warp yarns were conducted only using the micro-CT scanning from one angle of view to reduce scanning cost and yarn-to-yarn penetration error. An algorithm considering physical constraints of the yarns was also completed to estimate local fiber orientations with maximum error of 18.065°, nearly 50% smaller than the existing method.
微ct扫描是一种重建织物复合材料rve内部结构的先进技术。然而,目前很少有经济分辨率的自动方法从微ct图像中分离出紧密缠绕的纱线,这种方法只能识别纱线而不能识别单个纤维。为了解决这一问题,本工作开发了一种创新的方法,通过基于深度学习的图像分割来识别纱线的横截面面积,然后重建包含局部纤维取向的复合材料的三维几何模型。通过U-Net进行语义分割,mIOU计算验证准确率为87%;使用YOLO v8进行目标检测,mAP50计算验证准确率为99.5%。通过基于resnet50的图像分类网络,将不同形态特征的Micro-CT切片分成三组,按比例选择,形成具有较高代表性和效率的U-Net和YOLO v8的训练数据集。为了减少扫描成本和纱线间的穿透误差,只使用微ct扫描从一个角度提取经纱和纬纱的单个截面。提出了一种考虑纱线物理约束的局部纤维取向估计算法,最大误差为18.065°,比现有方法减小了近50%。
A comprehensive study of low-velocity impact behavior and damage evaluation of angle-ply thin woven GFRP composites under various temperatures
U.A. Khashaba
doi:10.1016/j.compscitech.2024.110608
不同温度下角层GFRP薄编织复合材料低速冲击性能及损伤评价的综合研究
The recent climatic changes have resulted in a significant increase in temperatures over 50°C during summer midday in certain countries. This has motivated the study of the low-velocity impact (LVI) response of angle-ply thin woven glass fiber-reinforced polymer composites under temperatures of 25°C, 50°C and 75°C. The LVI performance of the laminates was assessed by eighteen parameters. A new inexpensive image processing method is developed to accurately measure the damage diameter, area, and perimeter length, which significantly aids in analyzing the damage mechanisms under various test conditions. The damage perimeter length is a new parameter that is used to interprets the change of material behaviors with temperature. The LVI results showed that the impact bending stiffness is increased with impact energy (Ei) due to increasing strain rates, which leads to decreasing the molecular mobility of polymer chains and hence, the materials tend to behave more brittle. Delamination threshold force increased with impact energy and vice versa with temperature. Soaking the specimens for 1 h at 50°C improved post curing and thus, enhanced the cross linking density, which significantly improved most of the impact properties. The penetration energy threshold of 25.5J (85% of Ei) is observed at 30J-50°C. Relaxation of the polymer chain within the glass transition region at 75°C leads to full fracture energy threshold at 30J, which correlated with open force-deformation curve, absorbed energy of 100%, zero elastic energy, zero rebound energy, zero rebound velocity, and increase contact duration. The proposed multivariate regression models accurately predict the impact properties.
最近的气候变化导致某些国家夏季正午的气温大幅升高,超过 50°C。这促使我们对角形薄层玻璃纤维增强聚合物复合材料在 25°C、50°C 和 75°C 温度下的低速冲击(LVI)响应进行了研究。层压板的低速冲击性能由 18 个参数进行评估。开发了一种新的廉价图像处理方法来精确测量损伤直径、面积和周长,这大大有助于分析各种测试条件下的损伤机制。损伤周长是一个新参数,用于解释材料行为随温度的变化。LVI 结果表明,由于应变率的增加,冲击弯曲刚度随冲击能量(Ei)的增加而增加,这导致聚合物链的分子流动性降低,从而使材料表现得更脆。分层阈值力随冲击能量的增加而增加,反之亦然。将试样在 50°C 下浸泡 1 小时可改善后固化,从而提高交联密度,显著改善大部分冲击性能。在 30J-50°C 时,可观察到 25.5J 的穿透能阈值(Ei 的 85%)。聚合物链在 75°C 玻璃转变区内的松弛导致 30J 时达到完全断裂能阈值,这与开放的力-变形曲线、100% 的吸收能、零弹性能、零反弹能、零反弹速度和接触持续时间的增加相关。所提出的多元回归模型能准确预测冲击特性。
Torsional progressive damage mechanisms in 3-D braided carbon fiber/epoxy resin composite tubes
Limeng Xun, Yasmine Mosleh, Baozhong Sun, John-Alan Pascoe, Bohong Gu
doi:10.1016/j.compscitech.2024.110615
三维编织碳纤维/环氧树脂复合材料管扭转递进损伤机理
3-D braided composites are a promising material for manufacturing tubular structures. However, a thorough understanding of their damage mechanisms under torsion is required to maximize their potential applications. The present work constructed a multiscale equivalent model, integrating mesoscopic and homogeneous structures to reveal torsional behavior of 3-D braided carbon fiber/epoxy resin composite tubes. The cumulative failure process, spatial stress distribution and interface damage were calculated to illustrate stress transfer and damage initiation and propagation. It is found that stress varies on the surface and internally within the representative unit cell (RUC). The yarns experience both axial tension parallel to the direction of torsion and axial compression perpendicular to the direction of torsion. The stress difference between them leads to damage initiation and propagation. Interfacial cracking as main damage mode hinders the stress transfer between resin and fiber bundles. The results show that the braided yarn path, axial stress dispersion in two directions and localization of damage effectively impede the torsional damage propagation.
三维编织复合材料是一种很有前途的管状结构材料。然而,为了最大限度地发挥其潜在的应用潜力,需要彻底了解它们在扭转下的损伤机制。本文建立了一个多尺度等效模型,综合了细观和均相结构,揭示了三维编织碳纤维/环氧树脂复合材料管的扭转行为。计算了累积破坏过程、空间应力分布和界面损伤,说明了应力传递和损伤的发生和扩展。研究发现,应力在典型单元胞(RUC)表面和内部均有变化。纱线经历平行于扭转方向的轴向拉力和垂直于扭转方向的轴向压缩。它们之间的应力差导致了损伤的发生和扩展。界面开裂是树脂束与纤维束之间应力传递的主要破坏方式。结果表明:编织纱线的路径、轴向应力在两个方向上的分散和损伤的局部化有效地阻碍了扭转损伤的传播;