今日更新:Composite Structures 5 篇,Composites Part A: Applied Science and Manufacturing 2 篇,Composites Part B: Engineering 2 篇,Composites Science and Technology 1 篇
Design of multi-material structures using material jetting technology: Topology optimisation, numerical analysis and experiments
Marco Montemurro, Gianluca Alaimo, Enrico Panettieri, Anita Catapano, Massimo Carraturo, Ferdinando Auricchio
doi:10.1016/j.compstruct.2023.117838
利用材料喷射技术设计多材料结构:拓扑优化、数值分析和实验
This paper presents a thorough experimental/numerical validation of optimised multi-material structures fabricated by material jetting technology. The proposed methodology uses, on the one hand, non-uniform rational basis spline (NURBS) entities to represent the geometric descriptor associated with each material phase constituting the continuum and, on the other hand, a general multi-phase material interpolation scheme to penalise the stiffness tensor of the structure. Two design requirements are included in the problem formulation: the lightness and the minimum length scale of each material phase. The influence of the integer parameters intervening in the definition of the NURBS entity and the influence of different combinations of material phases on the optimised solutions are investigated. The proposed approach is applied to 2D and 3D benchmark structures subjected to prescribed displacements representative of a three-point bending test. Based on the result of the topology optimisation process one of the optimised solutions, balancing the requirements of structural stiffness, lightness, and manufacturing constraints, is selected, manufactured and tested. A comparison between experimental and numerical results (obtained by non-linear analyses) is carried out to show the effectiveness of the approach.
本文对利用材料喷射技术制造的优化多材料结构进行了全面的实验/数值验证。所提出的方法一方面使用非均匀有理基础样条曲线(NURBS)实体来表示与构成连续体的各材料相相关的几何描述符,另一方面使用一般多相材料插值方案来对结构的刚度张量进行惩罚。问题表述中包含两个设计要求:每个材料相的轻度和最小长度尺度。研究了 NURBS 实体定义中的整数参数的影响,以及不同材料相组合对优化解决方案的影响。所提出的方法适用于二维和三维基准结构,这些结构受到代表三点弯曲测试的规定位移的影响。根据拓扑优化过程的结果,在平衡结构刚度、轻度和制造限制等要求的基础上,选择、制造并测试了其中一个优化方案。对实验结果和数值结果(通过非线性分析获得)进行比较,以显示该方法的有效性。
All-Scale Approach to Evaluate the Elasticity and Strength of Carbon-Allotrope Reinforced Polyimide
Diogo Galhofo, António P. C. Duarte, Nuno Silvestre
doi:10.1016/j.compstruct.2023.117841
评估碳同位素增强聚酰亚胺弹性和强度的全尺度方法
This computational study conducts a comprehensive all-scale analysis to predict the mechanical behavior (elasticity and strength) of polyimide matrices (Kapton@) reinforced with carbon nanostructures, spanning nanoscale, microscale, mesoscale, and macroscale. Representative volume elements at each scale undergo tensile and shear loadings to extract mechanical properties. Homogenization techniques are applied to transition between scales, considering these properties. Two nanostructures (graphene and γ-graphyne) are explored as reinforcements, evaluating the influence of volume fraction and orientation on composite mechanical properties. Results are validated through comparison with theoretical, computational, and experimental studies. Composite materials exhibited significant improvements in stiffness (up to 44% at a volume fraction of 0.5%) and tensile strength (up to 25% at a volume fraction of 0.5%) compared to the pristine polymeric matrix.
这项计算研究进行了全面的全尺度分析,以预测用碳纳米结构增强的聚酰亚胺基质(Kapton@)的机械行为(弹性和强度),分析范围包括纳米尺度、微尺度、中尺度和宏观尺度。对每个尺度上的代表性体积元素进行拉伸和剪切加载,以提取机械性能。考虑到这些特性,均质化技术被应用于尺度之间的过渡。将两种纳米结构(石墨烯和γ-石墨烯)作为增强材料进行研究,评估体积分数和取向对复合材料机械性能的影响。通过与理论、计算和实验研究的比较,对结果进行了验证。与原始聚合物基体相比,复合材料在刚度(体积分数为 0.5%时可提高 44%)和拉伸强度(体积分数为 0.5%时可提高 25%)方面都有明显改善。
Probabilistic fatigue strength assessment of cross-ply laminates: Exploring effects of manufacturing defects through a two-scale modeling approach
Sara Eliasson, Gustav Hultgren, Zuheir Barsoum, Per Wennhage
doi:10.1016/j.compstruct.2023.117844
交叉层压板的概率疲劳强度评估:通过双尺度建模方法探索制造缺陷的影响
The study presents a two-scale modeling approach allowing for an efficient fatigue strength evaluation on a macro scale considering a micro-mechanical defect characterization of a Carbon Fiber Reinforced Polymer (CFRP) material. The modeling approach integrates a macro model with the effective elastic properties from micro-mechanical simulations considering voids. This enables the analysis of defects’ influence on material fatigue strength using a probabilistic weakest link approach. A CFRP laminate with a cross-ply layup was investigated. Two simulation case studies demonstrate the effect of void content and size on the characteristic fatigue strength. An experimental investigation was conducted testing the laminates in tension-tension fatigue verifying the predicted numerical behavior. The numerical models identify a difference in the characteristic fatigue strength consistent with the fatigue test results. It is numerically concluded that the investigated CFRP material’s fatigue strength is affected by the presence of voids and even with only a slight difference in the global void volume fraction a scatter in fatigue strength is identified.
该研究提出了一种双尺度建模方法,可在宏观尺度上对碳纤维增强聚合物(CFRP)材料的微观机械缺陷特征进行有效的疲劳强度评估。该建模方法将宏观模型与考虑到空隙的微观机械模拟得出的有效弹性特性相结合。这样就能利用概率最弱环节法分析缺陷对材料疲劳强度的影响。研究了一种交叉层叠的 CFRP 层压材料。两个模拟案例研究证明了空隙含量和大小对特征疲劳强度的影响。对层压板进行了拉伸疲劳试验,验证了预测的数值行为。数值模型确定的特征疲劳强度差异与疲劳测试结果一致。通过数值得出的结论是,所研究的 CFRP 材料的疲劳强度受到空隙的影响,即使整体空隙体积分数只有微小差异,疲劳强度也会出现差异。
Multiple blast resistance enhancement through negative-mass meta-honeycombs with multi-resonator
Yao Huang, Jiu Hui Wu, Shao Kun Yang, Li Bo Wang, Fuyin Ma
doi:10.1016/j.compstruct.2023.117845
通过多谐振器负质量元蜂窝增强多重抗爆能力
Conventional honeycomb materials are difficult to resist multiple blast because the enormous energy generated by the explosion would cause plastic deformation of the material, which weakens the strength of the structure. In this paper, a novel meta-honeycomb is designed by adding local resonance system to hierarchical cells, which is based on the multi-resonator-enhanced bandgap property, to withstand multiple blast. This meta-honeycomb reverses the energy absorption mode of traditional honeycomb materials; that is, the energy absorption by plastic deformation of the material becomes the reflection of the stress wave through the equivalent negative mass property generated by the local resonance system, which significantly reduces the deformation of the material and the reaction force at the support under impact loads. In particular, for the secondary explosion loading, the maximum deformation of the meta-honeycomb is reduced by 74% compared with the traditional hierarchical honeycomb. Furthermore, it is demonstrated that the design of meta-honeycomb can be optimized by coupling the bandgap generated by the negative mass property, thereby improving the energy absorption efficiency. This research result provides a new concept for the design of blast-proof materials, which has a high potential for a wide range of engineering applications.
传统的蜂窝材料很难抵御多重爆炸,因为爆炸产生的巨大能量会导致材料塑性变形,从而削弱结构的强度。本文基于多谐振器增强带隙特性,在分层单元中加入局部共振系统,设计出一种新型元蜂窝材料,以抵御多重爆炸。这种元蜂窝材料逆转了传统蜂窝材料的能量吸收模式,即通过局部共振系统产生的等效负质量特性,将材料塑性变形的能量吸收转变为应力波的反射,从而显著降低了冲击载荷下材料的变形和支撑处的反作用力。特别是在二次爆炸载荷下,元蜂窝的最大变形量比传统分层蜂窝减少了 74%。此外,研究还证明,通过耦合负质量特性产生的带隙,可以优化元蜂窝的设计,从而提高能量吸收效率。这项研究成果为防爆材料的设计提供了一个新概念,在广泛的工程应用中具有很大的潜力。
High-Tg shape memory polyimide composites with “spot-plane” directional thermally conduction structure based on AlN nanoparticles and acidified graphene
Xiaofei Wang, Yang He, Xinli Xiao, Wei Zhao, Jinsong Leng
doi:10.1016/j.compstruct.2023.117846
基于氮化铝纳米颗粒和酸化石墨烯的具有 "点平面 "定向热传导结构的高 Tg 形状记忆聚酰亚胺复合材料
In order to enhance the thermal conduction property and shorten response time of shape memory polyimide (SMPI), “spot-plane” directional thermally conductive acidified graphene/AlN/SMPI composites were prepared, in which AlN nanoparticles were used as “thermal conduction spots” and acidified graphene was used as two-dimensional “thermal conduction planes”. The SMPI composite doped with 6 wt% AlN and 0.8 wt% acidified graphene had good heat conducting properties (the in-plane thermal conductivity of 5.90 W m-1K-1), excellent mechanical propertied (the tensile strength of 134.5 MPa, and Young’s modulus of 3.8 GPa), high shape memory transition temperature (at 419 ℃), and great thermal stability and shape memory properties. Compared with SMPI resin matrix, the response time of the acidified graphene/AlN/SMPI composite was shortened by 140 s, only 20 s, and it can be applied in flexible electronics, intelligent response structures and active deformation structures in high-temperature environment.
为了提高形状记忆聚酰亚胺(SMPI)的热传导性能并缩短其响应时间,制备了 "点-面 "定向导热酸化石墨烯/AlN/SMPI 复合材料,其中 AlN 纳米颗粒被用作 "热传导点",而酸化石墨烯被用作二维 "热传导面"。掺杂了 6 wt% AlN 和 0.8 wt% 酸化石墨烯的 SMPI 复合材料具有良好的导热性能(面内导热系数为 5.90 W m-1K-1)、优异的力学性能(拉伸强度为 134.5 MPa,杨氏模量为 3.8 GPa)、较高的形状记忆转变温度(419 ℃)以及较好的热稳定性和形状记忆性能。与 SMPI 树脂基体相比,酸化石墨烯/AlN/SMPI 复合材料的响应时间缩短了 140 秒,仅为 20 秒,可应用于高温环境下的柔性电子器件、智能响应结构和主动变形结构。
Liquid crystal/polymer composites for energy-efficient smart windows with a wide working temperature range and low off-axis haze
Jianjun Xu, Zuowei Zhang, Longxiang He, Yingjie Shi, Yanzi Gao, Meina Yu, Huai Yang
doi:10.1016/j.compositesa.2023.107976
液晶/聚合物复合材料用于工作温度范围宽、离轴雾度低的节能智能窗
As a type of intelligent dimming film, polymer dispersed liquid crystal (PDLC) films show attractive application prospects in field of smart windows. However, their current performance cannot meet the requirement of outdoor window applications, especially in severe conditions, such as poor shielding effect at high temperature, delayed response at low temperature and high off-axis haze. To simultaneously solve these problems, a PDLC film was prepared by optimizing the structure of acrylate crosslinking agent and birefringence of LC, which exhibits good shielding effects and contrast ratio (10) at high temperature of 100 °C, short rise time (0.16 s) and decay time (2.4 s) at low temperature of -30 °C, and a satisfying low off-axis haze (on-state haze < 10% at ±45°, on-state transmittance > 65% at ±60°). This study provides meaningful supplements for the application of PDLC film in outdoor smart windows, especially in automotive smart windows under extreme weather conditions.
作为一种智能调光薄膜,聚合物分散液晶(PDLC)薄膜在智能窗户领域展现出诱人的应用前景。然而,目前其性能还不能满足户外窗户应用的要求,尤其是在恶劣条件下,如高温屏蔽效果差、低温响应延迟、离轴雾度大等。为了同时解决这些问题,研究人员通过优化丙烯酸酯交联剂的结构和 LC 的双折射,制备了一种 PDLC 薄膜,该薄膜在 100 ℃ 高温下具有良好的屏蔽效果和对比度(10),在 -30 ℃ 低温下具有较短的上升时间(0.16 秒)和衰减时间(2.4 秒),并且具有令人满意的低离轴雾度(±45° 时的通态雾度小于 10%,±60° 时的通态透射率大于 65%)。这项研究为 PDLC 薄膜在户外智能车窗,尤其是极端天气条件下的汽车智能车窗中的应用提供了有意义的补充。
Significance of transcrystalline layer formation on electrical conductivity of polyamide 6-carbon nanotube nanocomposites: An experimental and theoretical study
Mohammad Farhadpour, Javad Payandehpeyman, Mojtaba Mazaheri, Negar Irandoust, Gholamreza Pircheraghi, Reza Bagheri
doi:10.1016/j.compositesa.2023.107977
跨晶层的形成对聚酰胺 6-碳纳米管纳米复合材料导电性的影响:实验与理论研究
Electrical conductivity and mechanical properties of PA6/carbon nanofillers nanocomposites are highly dependent on the formation of PA6 transcrystalline layers onto the carbon nanofillers. In the current study, the substantial effects of PA6 viscosity and CNTs modification on transcrystalline layer formation in nanocomposites were investigated both experimentally and theoretically. FESEM, TEM, and solvent extraction observations showed almost identical morphological features for all samples, with well-dispersed carbon nanofillers within the matrix, and dispersed droplets morphology. Therefore, the differences in electrical conductivity among various nanocomposites were attributed to the only variable, which was differences in PA6 transcrystalline layer formation. It was found that employing high viscosity PA6, as well as modifying CNTs, both result in reduced transcrystalline layer formation and thus higher electrical conductivity, as corroborated by the theoretical modeling. Moreover, the evaluation of mechanical properties further elucidated that the transcrystalline layer formation can improve the tensile strength, Young’s modulus, and heat deflection temperature. Hence, on the one hand, transcrystalline layer formation endowed nanocomposites with superior mechanical properties due to the strong interfacial adhesion between the nanofillers and polymer matrix. On the other hand, however, it decreased the electrical conductivity by hindering electron tunneling through the dense and insulative transcrystalline layers.
PA6/ 碳纳米填料纳米复合材料的导电性和机械性能在很大程度上取决于 PA6 在碳纳米填料上形成的透晶层。本研究从实验和理论两方面研究了 PA6 粘度和 CNTs 改性对纳米复合材料透晶层形成的实质性影响。FESEM、TEM 和溶剂萃取观察结果表明,所有样品的形态特征几乎相同,碳纳米填料在基体中分散良好,液滴形态分散。因此,各种纳米复合材料导电性能的差异可归因于唯一的变量,即 PA6 晶体层形成的差异。研究发现,采用高粘度 PA6 和对 CNT 进行改性都会减少透晶层的形成,从而提高导电率,这也得到了理论模型的证实。此外,对力学性能的评估进一步阐明,跨晶层的形成可提高拉伸强度、杨氏模量和热变形温度。因此,一方面,由于纳米填料与聚合物基体之间具有很强的界面粘附性,跨晶层的形成赋予了纳米复合材料优异的力学性能。但另一方面,它阻碍了电子通过致密和绝缘的跨晶层,从而降低了导电性。
Mechanical properties of hierarchical lattice via strain gradient homogenization approach
Hua Yang, Zhenkun Liu, Yi Xia, Wei Fan, Ambrose C Taylor, Xu Han
doi:10.1016/j.compositesb.2023.111153
通过应变梯度均质化方法研究分层晶格的力学特性
With the advancement of 3D printing technology, manufacturing metamaterials with extreme mechanical properties is becoming more feasible. Hierarchical lattices appear to be ideal candidates for obtaining desirable lightweight, high specific stiffness, and enhanced specific energy absorption. They can be constructed by architected substructures at multiple length scales. The interpretations of the underlying deformation mechanisms are necessary in order to manipulate with expected mechanical properties. In this paper, experiments were conducted to examine the effective mechanical behaviors of hierarchical lattice metamaterials. A strain gradient homogenization approach has been employed to correlate their morphological characteristics to the resulting material properties. The effective stiffness tensors are identified including the fourth-, fifth-, and sixth-order stiffness tensors. The higher-order inertial parameters are determined by a fitting procedure. Comparisons between direct finite element analyses and the homogenized strain gradient continua have been made for hierarchical lattice materials under static and dynamic loads. It is found that strain gradient homogenization approach can be an accurate, efficient and reliable way of predicting the mechanical behaviors of hierarchical lattice. A systematic analysis of geometrical parameters was conducted to uncover the underlying mechanisms responsible for the enhancement of effective properties. This work offers a novel approach for designing the mechanical properties of hierarchical metamaterials through precise control of secondary structure types and distributions.
随着三维打印技术的发展,制造具有极端机械特性的超材料正变得越来越可行。分层晶格似乎是获得理想的轻质、高比刚度和增强比能量吸收的理想候选材料。它们可以通过多长度尺度的结构化子结构来构建。为了实现预期的机械性能,有必要对基本变形机制进行解释。本文通过实验研究了分层晶格超材料的有效力学行为。采用应变梯度均质化方法将其形态特征与由此产生的材料特性相关联。有效刚度张量包括四阶、五阶和六阶刚度张量。高阶惯性参数通过拟合程序确定。针对静态和动态载荷下的分层晶格材料,对直接有限元分析和均质化应变梯度连续体进行了比较。结果发现,应变梯度均质化方法可以准确、高效、可靠地预测分层晶格的力学行为。通过对几何参数进行系统分析,揭示了提高有效性能的内在机制。这项研究为通过精确控制次级结构类型和分布来设计分层超材料的力学性能提供了一种新方法。
Cellulose-based ultrastrong wood adhesive and composites constructed through “sandwich” profile bonding interface
Tongda Liu, Guanben Du, Hongxing Yang, Kelu Ni, Hang Su, Haozhang Wen, Byung-Dae Park, Xin Ran, Wei Gao, Mizi Fan, Long Yang
doi:10.1016/j.compositesb.2023.111169
纤维素基超强木材粘合剂和通过 "三明治 "型材粘合界面构建的复合材料
The present paper investigates the bonding interface between cellulose-based adhesive and chemically activated wood to explore the contribution of cohesion and interaction force between adhesive and substrate to the bonding properties. The activated wood surface rich in –NH2 groups is produced by brushing 3-amino-propyl triethoxysilane (APTES) on the natural wood. The amine-functionalized cellulose is made by grafting microcrystalline cellulose with APTES and the adhesive is developed by crosslinking the branched epoxide with the aminated cellulose. Subsequently, a super strong wood laminates is developed by reacting the –NH2 groups on the activated wood surface reacted with the epoxy groups in the adhesive to construct an “amino-epoxy-amino” sandwich bonding interface. The bonding strength of laminates at dry condition and after hot and boiling water treatment is 4.04 MPa, 2.42 MPa and 1.64 MPa, respectively. The strength after boiling water treatment of the plywood laminates made of all-component adhesive enhanced from 0 MPa to 1.64 MPa contrasted with that made of pure aminated cellulose and that prepared from the activated wood surface enhanced from 0.77 MPa to 1.64 MPa contrasted with that made by the nonactivated wood surface. The cohesion of the adhesive and the interaction force between the adhesive and the wood substrate played an important role in the bonding properties.
本文研究了纤维素基粘合剂和化学活化木材之间的粘合界面,以探讨粘合剂和基材之间的内聚力和相互作用力对粘合性能的贡献。在天然木材上刷涂 3-氨基丙基三乙氧基硅烷(APTES)可产生富含 -NH2 基团的活化木材表面。胺功能化纤维素是通过将微晶纤维素与 APTES 接枝制成的,而粘合剂则是通过支链环氧化物与胺化纤维素交联制成的。随后,活化木材表面的 -NH2 基团与粘合剂中的环氧基团发生反应,构建出 "氨基-环氧-氨基 "夹层粘合界面,从而制成超强木质层压板。层压板在干燥状态下以及经过热水和沸水处理后的粘合强度分别为 4.04 兆帕、2.42 兆帕和 1.64 兆帕。与纯胺化纤维素胶合板相比,全成分胶合剂胶合板经沸水处理后的强度从 0 兆帕提高到 1.64 兆帕,活化木材表面制备的胶合板与非活化木材表面制备的胶合板相比,强度从 0.77 兆帕提高到 1.64 兆帕。粘合剂的内聚力以及粘合剂与木材基材之间的相互作用力对粘合性能起着重要作用。
Effects of exposure in seawater sea-sand concrete pore solution on fatigue performance of carbon FRP bars
Qi Zhao, Xiao-Ling Zhao, Daxu Zhang, Li-Ping Duan
doi:10.1016/j.compscitech.2023.110418
暴露在海水海砂混凝土孔隙溶液中对碳玻璃钢条疲劳性能的影响
The study aims to propose a methodology to predict the fatigue performance of carbon fiber-reinforced polymer (CFRP) bars under the seawater sea-sand concrete (SWSSC) environment. The effects of exposure in SWSSC pore solution on the fatigue damage mechanisms and fatigue performance of CFRP bars are presented. Firstly, the tensile fatigue tests of reference CFRP bars were performed under various stress levels with a constant stress ratio of 0.1. Secondly, the tensile fatigue tests of exposed CFRP bars subject to the simulated SWSSC pore solution were carried out. The tensile failure modes and fatigue damage mechanisms corresponding to different stress levels, were identified using scanning electron microscopy (SEM). Besides, the relationship between fatigue life expectancy and underlying fatigue damage mechanisms was carefully analyzed. Finally, the effective stress level method (ESLM) was proposed to evaluate the residual fatigue life of exposed CFRP bars based on the benchmark S–N curve. Combined with the degradation models (chemical etching/diffusion models) proposed in our previous research, ESLM could bridge corrosion fatigue life prediction of the exposed CFRP bars and the benchmark fatigue data of the non-exposed CFRP reinforcement. The predicted results have good correlations with the experimental data. This method can also provide valuable insight for the corrosion fatigue life prediction of other types of FRP composites.
本研究旨在提出一种方法来预测碳纤维增强聚合物(CFRP)杆件在海水海砂混凝土(SWSSC)环境下的疲劳性能。介绍了暴露在 SWSSC 孔隙溶液中对 CFRP 杆件疲劳损伤机制和疲劳性能的影响。首先,在 0.1 恒定应力比的不同应力水平下对 CFRP 棒材进行了拉伸疲劳试验。其次,对暴露在模拟 SWSSC 孔隙溶液中的 CFRP 杆件进行了拉伸疲劳试验。使用扫描电子显微镜(SEM)确定了不同应力水平对应的拉伸失效模式和疲劳损伤机制。此外,还仔细分析了疲劳寿命与潜在疲劳损伤机制之间的关系。最后,根据基准 S-N 曲线,提出了有效应力水平法(ESLM)来评估裸 露 CFRP 杆件的残余疲劳寿命。结合之前研究中提出的降解模型(化学蚀刻/扩散模型),ESLM 可以将裸 露 CFRP 钢筋的腐蚀疲劳寿命预测与非裸 露 CFRP 钢筋的基准疲劳数据进行桥接。预测结果与实验数据具有良好的相关性。该方法还能为其他类型玻璃钢复合材料的腐蚀疲劳寿命预测提供有价值的见解。