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【新文速递】2023年12月28日复合材料SCI期刊最新文章

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今日更新:Composite Structures 1 篇,Composites Part A: Applied Science and Manufacturing 3 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 1 篇

Composite Structures

Coupled vibration analysis of bolted variable angle tow plates under combined nonlinear effects

Xiaofeng Liu, Wei Sun, Honghao Liu, Dongxu Du, Hongwei Ma, Hui Li

doi:10.1016/j.compstruct.2023.117847

 

组合非线性效应下螺栓连接变角拖板的耦合振动分析

To establish a dynamical modal of variable angle tow (VAT) plate accurately, the fiber path and fiber orientation of the VAT plate are described by high-order polynomials. Then, a simplified nonlinear joint model with interface dynamic partitioning is proposed to simulate the interface mechanical behavior of bolted joints. Based on these, a nonlinear semi-analytic dynamic model of the bolted VAT plate is built, which considers both material and joint nonlinearity and can accurately predict nonlinear vibration response. After verifying the proposed modeling method, a special bolted VAT plate is used as the analysis object for free vibration and forced vibration analysis. Firstly, the frequency veering behavior of the VAT plate caused by variations in boundary stiffness, connection stiffness, and fiber orientation is studied. Then, by analyzing the forced vibration response of the bolted VAT plate, it is found that under the combined effect of the modal interaction, material nonlinearity, and joint nonlinearity, the bolted VAT plate exhibited complex but rule-based nonlinear dynamic behavior. More importantly, the research work done in this paper has certain guiding significance for the optimization design of vibration resistance of a bolted VAT thin-walled structure with variable stiffness parameters and joint parameters as design variables.

为了准确建立变角丝束(VAT)板的动力学模态,用高阶多项式描述了变角丝束板的纤维路径和纤维取向。然后,提出了具有界面动态分区的简化非线性连接模型,以模拟螺栓连接的界面力学行为。在此基础上,建立了螺栓连接 VAT 板的非线性半解析动态模型,该模型同时考虑了材料和接头的非线性,可以准确预测非线性振动响应。在验证了所提出的建模方法后,以特殊的螺栓连接 VAT 板为分析对象,进行了自由振动和强迫振动分析。首先,研究了由边界刚度、连接刚度和纤维取向变化引起的 VAT 板频率偏移行为。然后,通过分析螺栓连接 VAT 板的受迫振动响应,发现在模态相互作用、材料非线性和连接非线性的共同作用下,螺栓连接 VAT 板表现出复杂但有章可循的非线性动态行为。更重要的是,本文的研究工作对于以可变刚度参数和连接参数为设计变量的螺栓连接 VAT 薄壁结构的抗振性优化设计具有一定的指导意义。


Composites Part A: Applied Science and Manufacturing

Micro structural design and macro synthesis of aerogel networks with gradient stiffness properties

Fuhua Xue, Qingyu Peng, Zonglin Liu, Xingchen Guo, Qian Yan, Xu Zhao, Xiaodong He

doi:10.1016/j.compositesa.2023.107978

 

具有梯度刚度特性的气凝胶网络的微观结构设计和宏观合成

Conductive aerogels have received extensive attention in a variety of application fields such as structural engineering and electrochemistry due to their lightweight, porous and conductive properties. The stiffness of aerogel is a key factor affecting its performance. So compared with conventional single-stiffness aerogels, the preparation of conductive aerogels with gradient stiffness properties is expected to achieve better stiffness matching and greater performance. Here, we develop a theoretical model of the gradient stiffness carbon nanotube (CNT) network and analyze the factors affecting the stiffness of the model from several perspectives, including spatial configuration and intrinsic parameters. Then, according to the guidance of the simulation results, actual CNT aerogels with gradient stiffness properties are successfully synthesized which have an ultra-wide range of stiffness variations. The unique lightweight gradient stiffness conductive aerogels are expected to show outstanding performance in many stiffness-dominated application fields.

导电气凝胶因其轻质、多孔和导电特性,在结构工程和电化学等多个应用领域受到广泛关注。气凝胶的刚度是影响其性能的关键因素。因此,与传统的单一刚度气凝胶相比,制备具有梯度刚度特性的导电气凝胶有望实现更好的刚度匹配和更高的性能。在此,我们建立了梯度刚度碳纳米管(CNT)网络的理论模型,并从空间构型和内在参数等多个角度分析了影响模型刚度的因素。然后,根据模拟结果的指导,成功合成了具有梯度刚度特性的实际碳纳米管气凝胶,其刚度变化范围极广。这种独特的轻质梯度刚度导电气凝胶有望在许多以刚度为主的应用领域展现出卓越的性能。


Investigation of laser-patterned biomimetic microstructures on CFRP and AA5052 surfaces to enhance their single-lap bonding strength

Shih-Feng Tseng, Yu-Sheng Chen, Tang-Wei Gao, Chil-Chyuan Kuo

doi:10.1016/j.compositesa.2023.107980

 

研究 CFRP 和 AA5052 表面的激光图案生物仿生微结构,以增强其单次粘接强度

This study focused on laser patterning of the biomimetic microstructures of gecko and tree frog patterns on the bonding surface of CFRP and AA5052 to improve their single-lap bonding strength. Laser-patterned biomimetic microstructures produced a rough surface and a superhydrophilic characteristic. A confocal laser microscope, contact angle measurement equipment and Fourier transform infrared spectroscopy were utilized to examine the surface roughness, wettability characteristic, and chemical bond of CFRP and AA5052, respectively. After the 8-week aging test, the lap shear strength of the test samples without pattern and with gecko and tree frog patterns was 2.22 ± 0.82 MPa, 9.26 ± 0.29 MPa, and 8.56 ± 0.15 MPa, respectively, which decreased approximately 75.8%, 10.96% and 13.09% compared to the unaging tests, respectively. The biomimetic microstructures of laser-ablated gecko patterns were helpful in enhancing the bonding strength of heterogeneous materials and in resisting drastic changes in the environment.

本研究的重点是在 CFRP 和 AA5052 的粘合表面上激光刻画壁虎和树蛙图案的仿生物微结构,以提高它们的单层粘合强度。激光图案化的仿生物微结构产生了粗糙的表面和超亲水性特征。利用激光共聚焦显微镜、接触角测量设备和傅立叶变换红外光谱仪分别检测了 CFRP 和 AA5052 的表面粗糙度、润湿特性和化学键。经过 8 周老化试验后,无花纹、有壁虎和树蛙花纹的试样的搭接剪切强度分别为 2.22 ± 0.82 MPa、9.26 ± 0.29 MPa 和 8.56 ± 0.15 MPa,与未老化试验相比,分别下降了约 75.8%、10.96% 和 13.09%。激光照射壁虎图案的仿生微结构有助于提高异质材料的粘接强度和抵抗环境的剧烈变化。


Magnetically assisted construction of Al2O3 platelets dual network and its excellent thermal conductivity in epoxy resin composites

Fanjun Guo, Kangle Xue, Tao You, Zibo Hua, Li Liu, Jun Li, Yudong Huang

doi:10.1016/j.compositesa.2023.107988

磁力辅助构建 Al2O3 小板双网络及其在环氧树脂复合材料中的优异导热性能

Constructing three-dimensional thermally conductive networks in polymer matrix is a key strategy to improve the thermal management performance of electronic packaging materials. However, optimizing the thermal conductivity of the composite while retaining its electrical insulation properties still requires further structural design. Herein, the heat-transferring Al2O3 platelets dual network was constructed by using a simple compression moulding method combined with a magnetic alignment strategy. Al2O3@Fe3O4 was used for the magnetic orientation arrangement in the vertical direction of the laminated Al2O3 framework. And the obtained Al2O3/Al2O3@Fe3O4/Epoxy composites possessed satisfactory thermal conductivity. The thermal conductivity of the composites containing 34.63 vol% filler was as high as 2.30 W/mK (K‖) and 1.83 W/mK (K⊥), which were significantly higher by 945% and 732% compared to epoxy resin. In addition, the introduction of Al2O3@Fe3O4 in the composite promoted isotropic thermal conductivity and provided electromagnetic shielding properties.

在聚合物基体中构建三维导热网络是提高电子封装材料热管理性能的关键策略。然而,在优化复合材料导热性能的同时保留其电气绝缘性能仍需要进一步的结构设计。在此,我们采用简单的压缩成型方法,结合磁性排列策略,构建了传热 Al2O3 小板双网络。Al2O3@Fe3O4 用于层叠 Al2O3 框架垂直方向的磁性取向排列。所获得的 Al2O3/Al2O3@Fe3O4/ 环氧树脂复合材料具有令人满意的导热性。含有 34.63 Vol% 填料的复合材料的导热系数分别高达 2.30 W/mK (K‖)和 1.83 W/mK (K⊥),与环氧树脂相比,分别显著提高了 945% 和 732%。此外,复合材料中 Al2O3@Fe3O4 的引入促进了各向同性导热性,并提供了电磁屏蔽性能。


Composites Part B: Engineering

3D printing of topologically optimized wing spar with continuous carbon fiber reinforced composites

Yiming Huang, Xiaoyong Tian, Wudan Li, Shiji He, Peng Zhao, Handong Hu, Qian Jia, Meng Luo

doi:10.1016/j.compositesb.2023.111166

用连续碳纤维增强复合材料 3D 打印拓扑优化机翼撑杆

The necessity for more efficient manufacturing approaches of high-performance complex fiber reinforced composites parts is increasing. This study develops a framework to design and produce topologically optimized continuous carbon fiber reinforced composites (CCFRCs) with both high manufacturing efficiency and manufacturability, and experimentally validates via material extrusion (MEX) 3D printing technique in a more than 1-m wing spar for the unmanned aerial vehicle (UAV). The load-carrying structure can be topologically optimized by a solid orthotropic material with penalization method and further designed into a continuous fiber trajectory under the consideration of optimal material density, optimal fiber orientation and 3D printing process limitation. Based on this method, the complex topological CCFRCs can be realized by a single-stroke printing path with intact fiber. The feasibility and effectiveness of the proposed framework have been evaluated on the Messerschmitt-Bölkow-Blohm (MBB) beam which reveals obvious higher performance in specific stiffness and peak load compared with commonly used honeycomb structure. As a case study, a topologically optimized UAV wing spar was designed and validated experimentally. Mechanical testing shows that the designed wing spar can survive in operating loads. Furthermore, a proof-of-concept internal wing structure was presented where conventional wing spar and ribs are replaced by CCFRCs 3D printed structures. It exhibits high load-carrying characteristics, is lightweight and simple to fabricate.

高性能复杂纤维增强复合材料部件越来越需要更高效的制造方法。本研究开发了一个框架,用于设计和生产拓扑优化的连续碳纤维增强复合材料(CCFRC),该框架具有较高的制造效率和可制造性,并通过材料挤压(MEX)3D 打印技术在无人机(UAV)超过 1 米的机翼撑杆上进行了实验验证。在考虑最佳材料密度、最佳纤维取向和三维打印工艺限制的情况下,该承载结构可通过带惩罚方法的固体正交材料进行拓扑优化,并进一步设计成连续纤维轨迹。基于这种方法,复杂拓扑结构的 CCFRC 可通过完整纤维的单冲打印路径实现。我们在梅塞施密特-伯尔考-布洛姆(MBB)梁上评估了所提框架的可行性和有效性,结果表明,与常用的蜂窝结构相比,该结构在比刚度和峰值载荷方面具有更高的性能。作为案例研究,我们设计了拓扑优化的无人机翼梁,并进行了实验验证。机械测试表明,所设计的翼撑能够在工作载荷下正常工作。此外,还展示了一种概念验证内部机翼结构,即用 CCFRC 3D 打印结构取代传统的翼尖和翼肋。该结构具有承载能力强、重量轻、制造简单等特点。


Composites Science and Technology

Cryogenic damage mechanisms of CFRP laminates based on in-situ X-ray computed tomography characterization

Yuanchen Li, Jinxin Meng, Guohao Niu, Heng Yang, Panding Wang, Hongshuai Lei, Daining Fang

doi:10.1016/j.compscitech.2023.110413

 

基于原位 X 射线计算机断层扫描表征的 CFRP 层压板低温损伤机理

Carbon fiber reinforced polymer (CFRP) composites possess excellent properties suitable for use in spacecraft liquid fuel tanks. However, the cryogenic reliability of composites remains challenging owing to the variation in mechanical responses under cryogenic environments. So far, most previous studies have focused on the cryogenic properties of composites, and little has been devoted to the cryogenic damage behaviors of laminates. Herein, the cryogenic damage evolution of CFRP laminates was investigated by micro-computed tomography (μCT) characterization and micromechanical analysis for the first time. To this end, in-situ μCT tensile tests for quasi-isotropic CFRP laminates were conducted at temperatures of 293 K, 193 K, and 93 K, and the observed cryogenic damage characteristics were analyzed. A micromechanical computational model was then developed, and the temperature-dependent constitutive model of epoxy resin was utilized to investigate the cryogenic damage evolution process of laminates. The effects of matrix property variation and thermal stresses on the cryogenic damage of laminates were examined, and the cryogenic fracture toughness for transverse cracking was deduced. The characterization results revealed a significantly increased damage volume fraction of laminates from 0.65% to 1.56% at cryogenic temperatures, mainly originating from the increased delamination (from 0.08% to 0.54%) and 90° ply transverse cracks (from 0.48% to 0.87%). The numerical analyses indicated the cryogenic brittle transition of the matrix as the primary factor responsible for the delamination, while the transverse cracks were influenced by matrix properties and thermal stresses. This study provides critical insight into the cryogenic damage behavior of CFRP laminates, essential for cryogenic applications of composites.

碳纤维增强聚合物(CFRP)复合材料具有适用于航天器液体燃料箱的优异性能。然而,由于低温环境下机械响应的变化,复合材料的低温可靠性仍然具有挑战性。迄今为止,以往的研究大多集中在复合材料的低温性能上,而对层压板的低温损伤行为研究较少。本文首次通过微计算机断层扫描(μCT)表征和微机械分析研究了 CFRP 层压板的低温损伤演变。为此,在 293 K、193 K 和 93 K 温度下对准各向同性 CFRP 层压板进行了原位 μCT 拉伸试验,并对观察到的低温损伤特征进行了分析。然后建立了微机械计算模型,并利用环氧树脂的温度依赖性构成模型研究了层压板的低温损伤演变过程。研究了基体性质变化和热应力对层压板低温损伤的影响,并推导出横向开裂的低温断裂韧性。表征结果表明,在低温条件下,层压板的损伤体积分数从 0.65% 显著增加到 1.56%,主要源于分层(从 0.08% 增加到 0.54%)和 90° 层横向裂纹(从 0.48% 增加到 0.87%)的增加。数值分析表明,基体的低温脆性转变是造成分层的主要因素,而横向裂纹则受到基体特性和热应力的影响。这项研究为 CFRP 层压板的低温损伤行为提供了重要见解,对复合材料的低温应用至关重要。



来源:复合材料力学仿真Composites FEM
ACTMechanicalMAGNET振动断裂复合材料非线性化学拓扑优化航天电子ADSUG裂纹理论化机材料仿生试验
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首次发布时间:2024-11-05
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【新文速递】2023年12月21日复合材料SCI期刊最新文章

今日更新:Composite Structures 6 篇,Composites Part A: Applied Science and Manufacturing 2 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 1 篇Composite StructuresEnvelope enrichment method for homogenization of non-periodic structuresFlorian Vazeille, Louis Laberge Lebeldoi:10.1016/j.compstruct.2023.117819非周期性结构均质化的包络富集法The homogenization of composite materials is critical for accurately predicting their mechanical performance, particularly when complex reinforcement arrangements are involved. Microstructural characteristics exert a substantial influence on the composite’s properties during practical applications. A widely adopted approach for analyzing composites is the numerical simulation of a Representative Volume Element (RVE). Although this method is well-established for periodic RVEs, it encounters difficulties when applied to non-periodic meshes, which complicates the imposition of classical boundary conditions on nodes exhibiting varying properties. To address this challenge, we propose a novel methodology that involves modeling an envelope surrounding the RVE, to which periodic boundary conditions are applied. By defining the envelope as a homogeneous material, stress transmission to the RVE is facilitated. The stiffness tensor of the envelope is updated iteratively through a homogenization process, ultimately converging to the effective properties of the RVE. The method is validated on a non-periodic arrangement of spherical inclusions embedded within a matrix. Convergence is observed in the different cases studied within ten iterations and the results are found within the Voigt and Reuss bound.复合材料的均质化对于准确预测其机械性能至关重要,尤其是在涉及复杂的增强排列时。在实际应用中,微观结构特征对复合材料的性能有很大影响。一种广泛采用的复合材料分析方法是代表性体积元素(RVE)数值模拟。虽然这种方法在周期性 RVE 中得到了广泛应用,但在应用于非周期性网格时却遇到了困难,这使得在显示不同属性的节点上施加经典边界条件变得复杂。为解决这一难题,我们提出了一种新方法,即对 RVE 周围的包络建模,并对其施加周期性边界条件。通过将包络定义为均质材料,可促进应力向 RVE 的传递。包络的刚度张量通过均质化过程迭代更新,最终收敛到 RVE 的有效属性。该方法在嵌入矩阵中的球形夹杂物的非周期性排列上进行了验证。在所研究的不同情况下,均在十次迭代内收敛,结果在 Voigt 和 Reuss 约束内。Design-oriented Stress-strain Model for RC Columns with Dual FRP- Steel Confinement MechanismJavad Shayanfar, Joaquim A. O. Barros, Mohammadali Rezazadehdoi:10.1016/j.compstruct.2023.117821采用玻璃钢-钢双重约束机制的 RC 柱应力-应变模型的设计导向性Many research studies have been conducted to evaluate confinement-induced enhancements on the mechanical properties of FRP (fiber-reinforced polymers)-confined plain concrete elements subjected to axial compressive loading, leading to the development of extensive predictive models. Nevertheless, experimental stress-strain results for FRP-confined RC columns (FCRC) have demonstrated some behavioural features that cannot be simulated accurately through this kind of model, developed exclusively for FRP-confined concrete columns (FCC). In this paper, a new design-oriented stress-strain model is proposed for the prediction of load-carrying capacity versus axial strain relationship of FCRC. For this purpose, a new parabolic stress-strain expression is developed for calculating the first branch of FCRC’s response up to the transition zone, followed by a linear function. New formulations are proposed to determine the first branch’s stress-strain gradient, transition zone-related information and the second branch’s slope, calibrated using a large test database of FCRC. The proposed design-oriented model is capable of simulating accurately the combined influence of the dual FRP and steel confinement on load-carrying capacity versus axial strain relationship of FCRC. Lastly, the capability of this model is validated by comparison to existing experimental data of FCRC and those obtained from some of existing models in the literature.为了评估纤维增强聚合物(FRP)约束素混凝土构件在承受轴向压缩荷载时由约束引起的力学性能增强,已经开展了许多研究,并开发了大量预测模型。然而,FRP 密实 RC 柱(FCRC)的应力-应变实验结果表明,这种专门为 FRP 密实混凝土柱(FCC)开发的模型无法准确模拟某些行为特征。本文提出了一种以设计为导向的新应力应变模型,用于预测 FCRC 的承载能力与轴向应变关系。为此,开发了一种新的抛物线应力-应变表达式,用于计算 FCRC 直至过渡区的第一个响应分支,随后是一个线性函数。提出了新的公式来确定第一分支的应力-应变梯度、过渡区相关信息和第二分支的斜率,并使用 FCRC 的大型测试数据库进行校准。所提出的以设计为导向的模型能够准确模拟玻璃钢和钢双重约束对 FCRC 承载能力与轴向应变关系的综合影响。最后,通过与现有 FCRC 试验数据以及文献中一些现有模型所获得的数据进行比较,验证了该模型的能力。An enhanced constitutive model to predict plastic deformation and multiple failure mechanisms in fibre-reinforced polymer composite materialsI.R. Cózar, F. Otero, P. Maimí, E.V. González, A. Turon, P.P. Camanhodoi:10.1016/j.compstruct.2023.117696预测纤维增强聚合物复合材料塑性变形和多重失效机制的增强构效模型Spurious damage modes in continuum damage mechanics models for fiber-reinforced polymer composite materials based on the effective stress tensor can be generated when large strains occur. A methodology to prevent this spurious phenomenon is developed in the present work. The longitudinal damage activation functions are based on the effective stress tensor, however, nominal stresses are used on the transverse damage activation functions. The proposed method can be straightforwardly implemented on previously-developed constitutive models which use effective stress tensor, an explicit implementation of the proposed constitutive model is presented. The enhancement of the predicted failure mechanisms obtained from the present constitutive model, with respect to the models which use effective stress tensor, is demonstrated. The proposed constitutive model presents a good agreement of the predicted failure pattern obtained from open-hole compressive experimental tests, as well as on the predicted failure strength.在基于有效应力张量的纤维增强聚合物复合材料连续损伤力学模型中,当出现大应变时可能会产生假损伤模式。本研究开发了一种方法来防止这种虚假现象。纵向损伤激活函数基于有效应力张量,而横向损伤激活函数则使用名义应力。所提出的方法可以在以前开发的使用有效应力张量的构成模型上直接实施,本文介绍了所提出的构成模型的明确实施方法。与使用有效应力张量的模型相比,本构成模型所预测的破坏机制得到了增强。建议的构成模型与开孔压缩实验测试得出的预测破坏模式以及预测破坏强度具有良好的一致性。Mass lumping schemes fitted to MLS-based numerical manifold method in vibration of plates with cutouts using CPT and FSDTShuaixing Zhao, Shan Lin, Miao Dong, Hongwei Guo, Hong Zhengdoi:10.1016/j.compstruct.2023.117815 在使用 CPT 和 FSDT 的带切口的板振动中,基于 MLS 的数值流形方法适用的质量叠加方案It is critical to accurately extract the natural frequencies in the transverse vibration of plates using the classical plate theory (CPT) and the first-order shear deformation plate theory (FSDT). The moving least squares (MLS) based numerical manifold method (MLS-based NMM) in conjunction with a suitable diagonally lumped mass matrix is a reasonable choice because it can naturally treat plates with cutouts and easily formulate an H2 regular approximation based on MLS interpolation, as well as mitigate shear locking issues for vibration analysis of thin plates based on FSDT. Moreover, the mass lumping techniques involving the row-sum method, the diagonal scaling method, and the mathematically rigorous manifold-based method are extended and derived in the unified framework of MLS-based NMM for transverse vibration analysis of plates. Furthermore, the positive-definiteness of the lumped mass matrix (LMM) generated by the manifold-based mass method is explained in MLS settings, and the row-sum method is proven to be a special case of the manifold-based method. A comprehensive comparative study of different LMMs is performed in accordance with the consistent mass matrix (CMM) on extensive numerical benchmarks. Numerical results demonstrate the convergence properties of LMMs compared with CMM in MLS-based NMM for plate vibration based on CPT and FSDT. It can be observed that LMMs yield comparable performance compared with CMM. The row-sum method obtains accurate results in most cases but can not guarantee the positivity. In contrast, the manifold method can guarantee the positive-definiteness of LMM and is more accurate than the diagonal scaling method in most cases.利用经典板理论(CPT)和一阶剪切变形板理论(FSDT)精确提取板横向振动的固有频率至关重要。基于移动最小二乘法(MLS)的数值流形方法(MLS-based NMM)与合适的对角块状质量矩阵相结合,是一种合理的选择,因为它可以自然地处理带有切口的板,并能轻松地根据 MLS 的移动最小二乘法和对角块状质量矩阵制定出 H2 正则近似,还能缓解基于 FSDT 的薄板振动分析中的剪切锁定问题。此外,在基于 MLS 的 NMM 统一框架下,扩展并推导了涉及行和法、对角线缩放法和基于流形的数学严谨方法的质量叠加技术,用于板的横向振动分析。此外,还解释了基于流形的质量矩阵(LMM)在 MLS 环境下的正定义性,并证明行和法是基于流形方法的特例。根据一致质量矩阵(CMM),在大量数值基准上对不同的 LMM 进行了全面的比较研究。数值结果表明,在基于 CPT 和 FSDT 的板振动 MLS NMM 中,与 CMM 相比,LMM 具有收敛特性。可以看出,与 CMM 相比,LMM 的性能相当。行和法在大多数情况下都能得到精确的结果,但不能保证正向性。相比之下,流形法可以保证 LMM 的正定义性,并且在大多数情况下比对角缩放法更精确。Analysis and Experiments of Bi-stable Laminate Configuration Control Based on MFC Piezoelectric ActuationYulin Jiang, Lu Yang, Chaofeng Li, Xueyang Miaodoi:10.1016/j.compstruct.2023.117820基于 MFC 压电致动的双稳态层压板配置控制分析与实验This paper studies the configuration change control and the snap-through phenomenon of bi-stable laminate with the MFC piezoelectric plate. The kinetic and potential energy expressions of the piezoelectric bi-stable laminate were obtained based on the von-Karman hypothesis. The constitutive equations of the system were given using a six-parameter displacement model, and the potential function of the system was derived using Hamilton’s principle. The configuration changes of the piezoelectric bi-stable laminate under different geometrical conditions were analyzed. The influence of voltage on the bi-stable laminate configuration was studied by applying different driving voltages. The snap-through energy variation of the piezoelectric bi-stable laminate under different geometrical conditions was investigated. In the experimental part, the changes in bi-stable laminate configuration with different geometrical conditions and after attaching the piezoelectric plate were compared. Different driving voltages were applied to measure the difference in piezoelectric bi-stable laminate configuration, and the critical snap-through voltages were recorded. The measured changes in bi-stable laminate configuration and snap-through voltage at different voltages prove the correctness of the theoretical presentation.本文研究了带有 MFC 压电板的双稳态层压板的构型变化控制和快穿现象。根据 von-Karman 假设得到了压电双稳态层压板的动能和势能表达式。利用六参数位移模型给出了系统的构成方程,并利用汉密尔顿原理推导出了系统的势函数。分析了压电双稳态层压板在不同几何条件下的构型变化。通过施加不同的驱动电压,研究了电压对双稳态层压板构型的影响。研究了压电双稳态层压板在不同几何条件下的快穿能量变化。在实验部分,比较了不同几何条件下和安装压电板后双稳态层压板配置的变化。通过施加不同的驱动电压来测量压电双稳态层压板配置的差异,并记录临界击穿电压。在不同电压下测得的双稳态压电片配置和速通电压的变化证明了理论表述的正确性。Comprehensive 3-D homogenization approach for predicting mechanical properties and creep behavior of polymer nanocomposites reinforced with graphene nanoplateletsHadi Mehdipour, Abbas Rohani Bastami, Mohammad Hossein Soorgeedoi:10.1016/j.compstruct.2023.117823预测石墨烯纳米片增强聚合物纳米复合材料力学性能和蠕变行为的综合三维均质化方法The aim of this study is to provide a comprehensive 3-D homogenization approach based on the high-fidelity generalized method of cells method to predict the mechanical properties and creep behavior of polymer nanocomposite reinforced with graphene nanoplatelets. Several fundamental experimental aspects including the volume fraction, size, and random orientation of graphene nanoplatelets, the interphase region, and the aggregation state of nanofillers of graphene are taken into account. The present study introduces two novel perspectives. At first, the aggregation of graphene nanoplatelets is formulated as dependent on volume fraction. Then the size of graphene is formulated as an important factor affecting the interphase region and the mechanical properties of polymer nanocomposite. Micromechanical tests conducted using the proposed method illustrate the good agreement with experimental data. The results of the parametric study on different experimental aspects revealed important findings. (i) For a specific value of graphene nanoplatelet volume fraction, the mechanical properties of polymer nanocomposite are at the best state. By increasing the graphene content beyond the specified graphene content value, the effective properties of graphene are decreased. (ii) The size of graphene nanoplatelets and the characteristics of the graphene/polymer interphase region have a direct effect on the properties of the nanocomposite.本研究旨在提供一种基于高保真广义单元法的综合三维均质化方法,用于预测石墨烯纳米片增强聚合物纳米复合材料的力学性能和蠕变行为。本研究考虑了几个基本的实验方面,包括石墨烯纳米片的体积分数、尺寸和随机取向、相间区域以及石墨烯纳米填料的聚集状态。本研究提出了两个新观点。首先,石墨烯纳米小板的聚集取决于体积分数。然后,石墨烯的尺寸被认为是影响相间区域和聚合物纳米复合材料机械性能的重要因素。使用所提出的方法进行的微机械测试表明,该方法与实验数据非常吻合。不同实验方面的参数研究结果揭示了重要的发现。(i) 在特定的石墨烯纳米颗粒体积分数值下,聚合物纳米复合材料的力学性能处于最佳状态。当石墨烯含量超过规定值时,石墨烯的有效性能就会下降。(ii) 石墨烯纳米小板的尺寸和石墨烯/聚合物相间区的特性直接影响纳米复合材料的性能。Composites Part A: Applied Science and ManufacturingRationally Designed Conductive Wood with Mechanoresponsive Electrical ResistanceGabriella G. Mastantuoni, Van Chinh Tran, Jonas Garemark, Christopher H. Dreimol, Isak Engquist, Lars A. Berglund, Qi Zhoudoi:10.1016/j.compositesa.2023.107970 合理设计具有机动力电阻的导电木材Porous cellular foams, combining lightweight, high strength, and compressibility, hold great promise in a wide range of advanced applications. Here, the native structure of pine wood was modified by in-situ lignin sulfonation and unidirectional freezing, resulting in an alveolate structure inside the wood cell wall with arrays of sub-100 nm channels. The obtained wood foam exhibited highly enhanced permeability while retaining the native cellular arrangement and high lignin and hemicellulose content. Such engineered cellular foam contributed to superior mechanical performance with compressive strength of 9 MPa and Young’s modulus of 344 MPa in the longitudinal direction. The high porosity allowed homogeneous infiltration of conductive polymer PEDOT:PSS inside the wood cell wall. The resulting composite exhibited high conductivity, sponge-like compressibility and the ability to modulate electrical resistance in a reversible manner in the radial direction. This rationally designed conductive wood demonstrated potential in durable and ultrasensitive pressure-responsive devices and strain sensors.多孔细胞泡沫集轻质、高强度和可压缩性于一身,在广泛的先进应用中大有可为。在这里,通过原位木质素磺化和单向冷冻改变了松木的原生结构,从而在木材细胞壁内形成了具有亚 100 纳米通道阵列的泡孔结构。获得的木质泡沫在保留了原生细胞排列以及高木质素和半纤维素含量的同时,还大大提高了透气性。这种工程蜂窝泡沫具有卓越的机械性能,纵向抗压强度达 9 兆帕,杨氏模量达 344 兆帕。高孔隙率使导电聚合物 PEDOT:PSS 能够均匀地渗入木细胞壁内。由此产生的复合材料具有高导电性、海绵般的可压缩性,并能在径向以可逆的方式调节电阻。这种设计合理的导电木材在耐用、超灵敏的压力响应设备和应变传感器方面表现出了潜力。Effects of Cellular Crossing Paths on Mechanical Properties of 3D Printed Continuous Fiber Reinforced Biocomposite Honeycomb StructuresPing Cheng, Kui Wang, Yong Peng, Said Ahzidoi:10.1016/j.compositesa.2023.107972细胞交叉路径对三维打印连续纤维增强生物复合蜂窝结构机械性能的影响3D printing continuous fiber reinforced composite (CFRC) has the advantages of manufacturing complex shapes and short production cycles. Due to the anisotropic mechanical properties of continuous fibers, the printing path of the fibers determines the properties of the printed CFRCs. In this paper, a series of novel cellular crossing paths were proposed to print continuous ramie fiber reinforced biocomposite honeycomb structures (CFHSs). The compression, bending, and tensile tests were performed to analyze the effects of cellular crossing paths on the mechanical properties of CFHSs. An assessment method was presented for analyzing the comprehensive mechanical properties of CFHSs printed by different printing paths. The results showed that the CFHSs printed by no-crossing path (Path-1), single-crossing path (Path-3), and double-crossing path (Path-4) exhibited better compression, bending, and tensile properties, respectively. In addition, the samples printed by Path-3 were the most outstanding in the assessments of comprehensive mechanical properties, the comprehensive performance assessment score was 1.5 times that of the single-crossing path (Path-2, minimum score). Thus, an appropriate cellular crossing path could be selected according to the structural load-bearing state, thereby providing higher mechanical properties.三维打印连续纤维增强复合材料(CFRC)具有制造复杂形状和生产周期短的优点。由于连续纤维具有各向异性的力学性能,纤维的打印路径决定了打印出的 CFRC 的性能。本文提出了一系列新颖的蜂窝交叉路径,用于打印连续苎麻纤维增强生物复合蜂窝结构(CFHS)。通过压缩、弯曲和拉伸试验,分析了蜂窝交叉路径对 CFHS 力学性能的影响。还提出了一种评估方法,用于分析不同印刷路径印刷的 CFHS 的综合力学性能。结果表明,无交叉路径(路径-1)、单交叉路径(路径-3)和双交叉路径(路径-4)印刷的 CFHS 分别具有更好的压缩、弯曲和拉伸性能。此外,路径-3 印刷的样品在综合机械性能评估中表现最为突出,其综合性能评估得分是单交叉路径(路径-2,得分最低)的 1.5 倍。因此,可以根据结构承载状态选择合适的蜂窝交叉路径,从而提供更高的机械性能。Composites Part B: EngineeringHierarchical rigid porous composites towards impact resistance and fire safetyYongqian Shi, Ruizhe Huang, Miao Liu, Junqiang Han, Peihui Xu, Yuezhan Feng, Libi Fu, Fuqiang Yang, Bin Yudoi:10.1016/j.compositesb.2023.111139 实现抗冲击和防火安全的分层刚性多孔复合材料Impact injuries and fire risks generally coexist simultaneously in extreme environments. In this context, it is of great necessity to design impact resistant materials with both flame retardant performance and thermal stability. Here, a multi-functional flame retardant coating was prepared from the combination of silica sol (Si-sol), phytic acid (PA) and expandable graphite (EG) by graft modification with γ-propyl-trimethoxysilane (KH550). Subsequently, hierarchical composites were fabricated using one-pot foaming and brush coating method, where the carbon fiber cloth and coating served as the surface layer, while rigid polyurethane foams (RPUF) acted as the interlayer. The hierarchical structure endowed the RPUF composites with high compression resistance and impact resistance properties. Furthermore, the flame retardant coating could effectively reduce the values of peak heat release rate and peak smoke production rate of RPUF composites by 77.5% and 81.8%, respectively. Therefore, these RPUF composites can effectively prevent impact damage and achieve excellent flame retardancy, making them promising candidates as safety protective materials.在极端环境中,撞击伤害和火灾风险通常同时存在。在这种情况下,设计兼具阻燃性能和热稳定性的抗冲击材料就显得尤为必要。在此,我们采用γ-丙基三甲氧基硅烷(KH550)接枝改性的方法,制备了一种由硅溶胶(Si-sol)、植酸(PA)和可膨胀石墨(EG)组合而成的多功能阻燃涂层。随后,采用一锅发泡和刷涂法制备了分层复合材料,其中碳纤维布和涂层作为表层,硬质聚氨酯泡沫(RPUF)作为中间层。分层结构使 RPUF 复合材料具有较高的抗压和抗冲击性能。此外,阻燃涂层还能有效降低 RPUF 复合材料的峰值放热率和峰值产烟率,降幅分别为 77.5% 和 81.8%。因此,这些 RPUF 复合材料能有效防止冲击损伤,并具有优异的阻燃性能,有望成为安全防护材料。Composites Science and TechnologyAn innovative tunable bimodal porous PCL/gelatin dressing fabricated by electrospinning and 3D printing for efficient wound healing and scalable productionErfan Rezvani Ghomi, Vijila Chellappan, Rasoul Esmaeely Neisiany, Nileshkumar Dubey, Kottaiswamy Amuthavalli, Navin Kumar Verma, Rajamani Lakshminarayanan, Seeram Ramakrishnadoi:10.1016/j.compscitech.2023.110402 通过电纺丝和三维打印技术制造的创新型可调双模多孔 PCL/明胶敷料,可实现高效伤口愈合和规模化生产This study presents the development of tunable scaffolds with bimodal porosity comprising poly(ε-caprolactone) (PCL) micro-meshes and PCL/gelatin/ε-polylysine (ε-PL) fibrous layers. Pure PCL scaffolds were prepared using the fused deposition modeling technique featuring grid geometry and interconnected micro-pores, followed by electrospinning to produce PCL/gelatin/ε-PL nanofibrous layers. Field emission scanning electron microscopy was employed to investigate the morphological features of the scaffolds, while the physicomechanical properties were studied using tensile and contact angle tests. Antibacterial performance and skin cell toxicity of the scaffolds were determined by bacterial disc diffusion and viability assays, respectively. Morphological analysis showed the presence of micro-to nano-sized pores in the developed scaffolds. The mechanical test results revealed that the prepared scaffolds exhibited Young's modulus values similar to the human skin with higher strain. The nanocomposite scaffolds were cytocompatible and effectively eradicated common bacteria associated with cutaneous wounds. In light of the aforementioned results along with facile fabrication, the tunable PCL/gelatin/ε-PL porous scaffolds hold great promise for applications in skin wound repair.本研究介绍了由聚(ε-己内酯)(PCL)微网格和 PCL/明胶/ε-聚赖氨酸(ε-PL)纤维层组成的具有双峰孔隙率的可调支架的开发过程。纯 PCL 支架是利用熔融沉积建模技术制备的,具有网格几何形状和相互连接的微孔,然后通过电纺丝产生 PCL/明胶/ε-PL 纳米纤维层。利用场发射扫描电子显微镜研究了支架的形态特征,并通过拉伸和接触角测试研究了其物理机械性能。细菌盘扩散和存活率试验分别测定了支架的抗菌性能和皮肤细胞毒性。形态学分析表明,所制备的支架中存在微到纳米级的孔隙。力学测试结果表明,所制备支架的杨氏模量值与人体皮肤相似,但应变较大。纳米复合材料支架具有细胞相容性,能有效消灭与皮肤伤口有关的常见细菌。鉴于上述结果和简便的制备方法,可调 PCL/明胶/ε-PL 多孔支架在皮肤伤口修复中的应用前景广阔。来源:复合材料力学仿真Composites FEM

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