今日更新:Composite Structures 3 篇,Composites Part A: Applied Science and Manufacturing 2 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 1 篇
Low-velocity impact behaviour of flat and tapered Single-Double composites specimens
Alessandro Vescovini, Carina Xiaochen Li, Cecilia Malverti, Bo Cheng Jin, Andrea Manes
doi:10.1016/j.compstruct.2024.118823
扁平和锥形单-双复合材料试样的低速冲击行为
This study examines low-velocity impact on five specimen sets produced using the card-sliding technique with non-crimp fabrics (NCFs) and adopting a Single-Double (SD) stacking sequence. Two sets of specimens are flat with a constant cross-section, fabricated with ±45° and ±30° NCF orientations, respectively. Two other sets feature a tapered cross-section with the same NCFs as the flat specimens, and the fifth set comprises tapered specimens with the same fiber orientations as one of the tapered sets but incorporates NCFs with varied areal density. The specimens undergo testing according to the ASTM international standard, with thermal transients during impacts recorded using an infrared camera. Finite Element Method (FEM) analyses are validated against and compared with experimental results. The study discusses impact behavior and failure modes, focusing on various damage mechanisms, emphasizing the effects of the tapered cross-section, different NCFs, and stacking sequence. This investigation elucidates the response of NCF composite materials to low-velocity impacts, highlights the benefits of the SD stacking sequence and card-sliding technique in tapering the laminate cross-section, and underscores their potential in reducing delamination and promoting intra-laminar failure, thereby enhancing composite durability and performance.
本研究对采用滑卡技术制作的五组试样进行了低速冲击试验,这些试样使用了非织造布(NCF)并采用了单双(SD)层压顺序。其中两组试样为截面恒定的平板,分别采用±45°和±30°的 NCF 方向制作。另外两组试样具有锥形截面,所用 NCF 与平板试样相同,第五组试样为锥形试样,纤维方向与其中一组锥形试样相同,但采用了不同面积密度的 NCF。试样按照 ASTM 国际标准进行测试,冲击过程中的热瞬态变化通过红外摄像机记录。有限元法(FEM)分析结果与实验结果进行了验证和比较。研究讨论了冲击行为和失效模式,重点关注了各种损伤机制,着重分析了锥形截面、不同 NCF 和层压顺序的影响。这项研究阐明了 NCF 复合材料对低速冲击的响应,突出了 SD 堆叠顺序和卡片滑动技术在减小层压板横截面方面的优势,并强调了它们在减少分层和促进层内失效方面的潜力,从而提高复合材料的耐久性和性能。
Fiber-level automatic modeling strategy of 3D rotary braided preform based on motion information
Xin Yang, Cheng Lu, Siyi Bi, Chenglong Zhang, Huiqi Shao, Shaoju Fu, Jinhua Jiang, Frank K. Ko, Nanliang Chen
doi:10.1016/j.compstruct.2024.118832
基于运动信息的三维旋转编织预制件纤维级自动建模策略
Numerous intricate fiber architectures for composite preforms can be generated by the three-dimensional rotary braiding technique due to the individually controllable horn gear mechanism. Herein, a methodology for mesoscopic morphology prediction is presented to investigate the internal geometry of these architectures. The methodology involves an algorithm for carrier path prediction, a fiber element considering dynamics, the modifications of contact detection and the design of a friction force model. Furthermore, the accuracy of structure predictions for three types of fabrics is validated and the inner structure simulation is verified using X-ray CT scanning. Two representative unit cells for fabric characterization are proposed and parametric equations are established to describe the structure of unit cells. The parametric studies illustrate the significant influences of increase in horn gear slot number on the yarn number, the overall size of unit cell and the yarn volume fraction, but few effects on the yarn group.
由于单向角齿轮机构的可控制,三维旋转编织技术可以生成许多复杂的复合预制件纤维结构。本文提出了一种介观形态预测方法来研究这些结构的内部几何结构。该方法包括载流子路径预测算法、考虑动力学的纤维元件、接触检测的修正和摩擦力模型的设计。进一步验证了三种织物结构预测的准确性,并利用x射线CT扫描验证了内部结构模拟。提出了两种具有代表性的织物表征单元格,并建立了描述单元格结构的参数方程。参数化研究表明,增大喇叭齿轮槽数对成纱支数、单胞总尺寸和成纱体积分数有显著影响,但对成纱组的影响不大。
Mechanisms of defect formation and evolution in drilling thermoplastic CF/PEEK composite using twist and step drills
Xunxun Zhang, Jielin Chen, Haihang Wang, Tai Ma, Liangliang Lin, Lu Yang, Tao Wang, Weiwei Ming, Qinglong An, Ming Chen
doi:10.1016/j.compstruct.2024.118833
用麻花钻和阶梯钻钻热塑性CF/PEEK复合材料缺陷形成和演变机理
During the drilling of thermoplastic carbon fiber reinforced polyetheretherkrtone (CF/PEEK), significant issues such as material smearing, burr formation, and delamination arise due to the softening and melting of the matrix material when exposed to heat. This study delves into the mechanisms of damage formation and evolution during the drilling of CF/PEEK using twist drills equipped with chip-split grooves and two-step step drills. Various factors such as drilling temperature, thrust force, chip morphology, and machined surface quality were meticulously examined to understand the material removal mechanisms. A three-dimensional defect factor, accounting for burr, tearing, and delamination, was employed to assess the overall hole quality. The utilization of chip-split grooves led to the formation of spiral chips, effectively preventing chip creasing and clogging, reducing drilling temperature. Comparatively, Twist drills exhibited a 62% increase in drilling forces but an 18% decrease in drilling temperatures compared to step drills. Furthermore, twist drills demonstrated a notable 57% reduction in burr and tear areas and a significant 69% decrease in delamination areas. Analyzing the distribution of delamination, the exit delamination associated with the step drills was found to be 19% smaller than the twist drills, while the entrance delamination area was five times larger.
在热塑性碳纤维增强聚醚醚酮(CF/PEEK)的钻孔过程中,由于基体材料在受热时的软化和熔化,会出现材料涂抹、毛刺形成和分层等重大问题。本研究采用带切屑槽的麻花钻和两步法钻,探讨了CF/PEEK钻削过程中损伤的形成和演化机制。研究人员仔细检查了钻进温度、推力、切屑形貌和加工表面质量等各种因素,以了解材料的去除机制。三维缺陷因子,考虑毛刺,撕裂和分层,被用来评估整体孔质量。切屑劈开槽的利用导致螺旋切屑的形成,有效地防止了切屑压痕和堵塞,降低了钻进温度。相比之下,与阶梯钻相比,麻花钻的钻进力增加了62%,但钻进温度降低了18%。此外,麻花钻显示毛刺和撕裂区域显著减少57%,分层区域显著减少69%。通过对分层分布的分析,发现阶梯钻的出口分层面积比麻花钻小19%,而入口分层面积是麻花钻的5倍。
Predicting the tensile properties of wood plastic composites using material extrusion with meta-based Few-Shot learning
Zhuo Zeng, Yan Zhou, Shifeng Wen, Cheng Zhou
doi:10.1016/j.compositesa.2024.108671
基于元基Few-Shot学习的材料挤压拉伸性能预测
This study investigated the optimization of process parameters affecting the tensile properties of wood plastic composites (WPC) produced by material extrusion (MEX). In the field of MEX, determining the optimal process parameters is complex, and a lack of sufficient data constrains the application of existing applied machine learning methods. In this study, a meta-based few-shot regression framework involving semi-regression, meta-learning, and fine-tuning, was developed to accurately predict the tensile properties of MEX-formed WPC while avoiding overfitting. A small dataset with varying wood contents, printing temperatures, and layer thicknesses were used to predict Young’s modulus, tensile strength, and elongation at break, which demonstrated a 42.6%, 41.9%, and 40.3% improvement in accuracy, respectively, over multilayer perceptron (MLP) when applying the proposed method. The proposed method also demonstrated improved generalization and was validated against the MLP technique. The study concluded that meta-learning can effectively manage the small datasets typical in additive manufacturing, providing a robust tool for optimizing three-dimensional printing parameters.
研究了影响材料挤压法生产木塑复合材料拉伸性能的工艺参数优化。在MEX领域,确定最佳工艺参数是复杂的,并且缺乏足够的数据限制了现有应用机器学习方法的应用。在本研究中,开发了一种基于元的少次回归框架,包括半回归、元学习和微调,以准确预测mex形成的WPC的拉伸性能,同时避免过拟合。采用不同木材含量、打印温度和层厚度的小数据集来预测杨氏模量、抗拉强度和断裂伸长率,结果表明,与多层感知器(MLP)相比,应用该方法的精度分别提高了42.6%、41.9%和40.3%。该方法还证明了改进的泛化,并与MLP技术进行了验证。研究得出结论,元学习可以有效地管理增材制造中典型的小数据集,为优化三维打印参数提供了一个强大的工具。
Complementarities of nanoindentation and atomic force microscopy for exploring micromechanical features of ancient flax fibres
Camille Goudenhooft, Sylvie Durand, Célia Caër, Alessia Melelli, Anthony Magueresse, Olivier Arnould, Eric Balnois, Anita Quiles, Darshil U. Shah, Johnny Beaugrand, Alain Bourmaud
doi:10.1016/j.compositesa.2024.108694
纳米压痕与原子力显微镜在探索古亚麻纤维微力学特征中的互补作用
The use of flax (Linum usitatissimum L.) fibres for textile dates back to several millennia; in Ancient Egypt flax was widely used in many everyday items. While flax fibres continue to diversify today as composite reinforcements, the study of their historical use is highly relevant when it comes to their durability; archaeological samples offer unique lenses for understanding changes in intrinsic fibre properties after long–time periods. Through a comprehensive examination of ancient Egyptian flax fibres from four archaeological artefacts, this study carries out a detailed characterisation of the fibre ultrastructure and micromechanical properties by combining nanoindentation (NI) and atomic force microscopy (AFM). This work highlights the complementary of these techniques for both heritage and materials science; it demonstrates on some samples, the remarkable cell wall stiffness, even after thousands of years, which is a key element for the bio-based composites sector, to better understand the degradation mechanisms of plant fibres.
亚麻(Linum usitatissimum L.)纤维用于纺织品可以追溯到几千年前;在古埃及,亚麻被广泛用于许多日常用品。虽然亚麻纤维今天继续多样化的复合增强,其历史使用的研究是高度相关的,当它涉及到其耐久性;考古样本提供了独特的透镜,以了解长时间后内在纤维特性的变化。通过对四件考古文物中的古埃及亚麻纤维的全面检查,本研究结合纳米压痕(NI)和原子力显微镜(AFM)对纤维的超微结构和微力学性能进行了详细的表征。这项工作突出了这些技术对遗产和材料科学的补充;它在一些样品上展示了显著的细胞壁刚度,即使经过数千年,这是生物基复合材料部门的一个关键因素,以更好地了解植物纤维的降解机制。
In-Situ Cure Monitoring of Structural Composite by Embedment of Vertically Aligned Carbon Nanotube Forests
Tobias Karlsson, Abhik Dutta, Per Hallander, Malin Åkermo
doi:10.1016/j.compositesb.2024.112105
垂直排列碳纳米管森林嵌入结构复合材料的原位固化监测
The next generation of composite structures within aerospace is envisioned to evolve from a strictly mechanical to a multifunctional structure, adding functionalities to the structure by embedment of functional filler material or incorporation of foreign structures. The introduction of carbon nanotubes (CNTs) into the composite structure to achieve sensing capabilities is one example. In this paper, online cure monitoring of aerospace-grade glass fibre/epoxy prepreg laminates is performed by in-situ resistive measurements on embedded vertically aligned carbon nanotube (VACNT) forests. The measured resistance over the course of the cure cycle has a reproducibility in its shape, itself a reflection of the state of the embedded CNTs. The measured resistance is interpreted after studying the morphology of the VACNT forest, cure kinetics and viscosity of the resin, and volumetric changes of both resin and laminate during the cure cycle. The resistive signal is determined to detect the transition between the air-evacuation and consolidation regimes of the laminate compaction and the gel point of the epoxy. Unique observations after the gel point are recorded, theorised to be caused by the build-up of residual stresses in the laminate. The proposed cure monitoring sensor system offers great flexibility, being able to monitor the curing process locally anywhere in the laminate. Additionally, the proposed sensor offers a life-span multifunctionality to the produced component, possessing strain and temperature sensing capabilities in the cured state ideal for structural health monitoring.
航空航天领域的下一代复合材料结构预计将从严格的机械结构发展到多功能结构,通过嵌入功能填充材料或结合外部结构来增加结构的功能。将碳纳米管(CNTs)引入复合材料结构以实现传感能力就是一个例子。本文通过嵌入式垂直排列碳纳米管(VACNT)森林的原位电阻测量,对航空级玻璃纤维/环氧预浸层合板进行了在线固化监测。在固化周期过程中测量的电阻在其形状上具有可重复性,其本身反映了嵌入的CNTs的状态。通过研究VACNT森林的形态、固化动力学和树脂的粘度,以及树脂和层压板在固化周期内的体积变化来解释所测得的电阻。电阻信号被确定为检测层压实和环氧树脂凝胶点之间的抽气和固结状态的过渡。记录凝胶点后的独特观察,理论上是由层压板中残余应力的积累引起的。所提出的固化监测传感器系统提供了很大的灵活性,能够在层压板的任何地方监测局部固化过程。此外,所提出的传感器为生产的组件提供了一个寿命周期的多功能,在固化状态下具有应变和温度传感能力,非常适合结构健康监测。
LEGO-inspired fabrication strategy for aramid nanofibers-based multilayer aerogels with tunable multiple functions
Zhe Wang, Yang Zhou, Jiaxin Liu, Bingyang Ma, Won Seok Chi, Guan Heng Yeoh, Guanglan Liao, Tielin Shi, Hu Long
doi:10.1016/j.compscitech.2024.111029
基于芳纶纳米纤维的多种功能可调多层气凝胶的乐高启发制造策略
With the advantage of lightweight, thermal insulation and flame retardant, aramid nanofibers (ANFs)-based aerogel is a promising functional material in military, aerospace and complex environmental applications, but its functionality still needs to be further optimized. Herein, we propose a flexible fabrication strategy to prepare ANFs-based multilayer aerogels through the freeze-casting method, acid-assisted protonation, and freeze-drying. This process integrates various composite ANFs-based aerogel layers to achieve multiple functions, and utilizes the mechanical toughening effects of the porous skeleton and nano-units at both macroscopic and microscopic scales, ensuring strong interlayer bonding force and fluffier skeleton structure, just like the stacking and stitching of LEGO. The different multifunctional degrees of aerogels can be obtained by controlling the structural configuration. Through this process, ANFs-based aerogel with the multilayer configuration of SiC-CNT-SiC/ANF has the lightweight characteristics (0.04711 g/cm3), effective thermal insulation, flame retardant and compression properties (113.83 KPa), which also shows certain joule thermal performance.
芳纶纳米纤维(ANFs)气凝胶具有轻质、隔热、阻燃等优点,是一种在军事、航空航天和复杂环境中应用前景广阔的功能材料,但其功能仍需进一步优化。在此,我们提出了一种灵活的制备策略,通过冷冻铸造法、酸辅助质子化法和冷冻干燥法制备基于anfs的多层气凝胶。该工艺将多种基于anfs的复合气凝胶层集成在一起,实现多种功能,并在宏观和微观上利用多孔骨架和纳米单元的机械增韧作用,确保层间结合力强,骨架结构更蓬松,就像乐高的堆叠和拼接一样。通过控制气凝胶的结构构型,可以获得不同程度的多功能气凝胶。通过该工艺制备出具有SiC-CNT-SiC/ANF多层结构的anfs气凝胶,具有轻质特性(0.04711 g/cm3),有效的保温、阻燃和压缩性能(113.83 KPa),并表现出一定的焦耳热性能。