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【新文速递】2024年4月10日固体力学SCI期刊最新文章

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今日更新:Mechanics of Materials 1 篇,Thin-Walled Structures 4 篇

Mechanics of Materials

In-plane elastic waves in piezoelectric metamaterials with Parity–Time symmetry

Peng-Hui Li, Zi-Hao Miao, Yi-Ze Wang

doi:10.1016/j.mechmat.2024.105005

具有奇偶-时间对称性的压电材料中的面内弹性波

The propagation of in-plane waves in piezoelectric metamaterial involves the coupling of longitudinal (i.e. quasi–pressure), transverse (i.e. quasi–shear) and electric potential waves, which can result in different exotic phenomena. In this study, the stiffness matrix method is used to analyze the dispersion relation, which contains anomalous propagation characteristics. With the coupling of electric potential, the frequency spectrum of in–plane wave shows new characteristics. The exceptional point caused by non–Hermitian operator that does not exist before also appears when the vertical wave number is imaginary. The oblique incidence of the in–plane wave at the interface between a homogeneous medium and phononic crystal can excite multiple refraction modes which include the negative refraction. The normal mode decomposition is developed to study the in-plane incidence of piezoelectric metamaterial and then the averaged Poynting vector is applied to obtain the refraction angle. Moreover, the defect layer is introduced into the phononic crystals to study the transmission coefficients with two different symmetrical arrangements. When the balanced gain and loss are considered in the metamaterial, the Parity–Time symmetry appears and brings in pairs of exceptional points to achieve a complete transmission with a unidirectional zero reflection.

平面波在压电超材料中的传播涉及到纵波(即准压力波)、横波(即准剪切波)和电位波的耦合,从而导致不同的奇异现象。本文采用刚度矩阵法分析了包含异常传播特性的色散关系。随着电势的耦合,面内波的频谱呈现出新的特征。当纵波数为虚数时,以前不存在的非厄米算子引起的异常点也会出现。平面波在均匀介质和声子晶体界面处的斜入射可以激发包括负折射在内的多种折射模式。采用正交模态分解方法研究了压电材料的面内入射,并利用平均坡印亭矢量计算了折射角。此外,在声子晶体中引入缺陷层,研究了两种不同对称排列方式下的透射系数。当在超材料中考虑平衡增益和损耗时,奇偶-时间对称性出现并引入对异常点,从而实现单向零反射的完全传输。


Thin-Walled Structures

Buckling strengths of Cold-Formed Built-up Cruciform Section Columns under axial compression

Jelena Dobrić, Nina Gluhović, Nenad Fric, Xiongfeng Ruan, Marina Bock, Barbara Rossi

doi:10.1016/j.tws.2024.111879

冷弯组合十字形截面柱轴压屈曲强度研究

This paper describes experiments addressing the buckling and collapse behaviour of cold-formed stainless steel cruciform section columns. Doubly symmetrical flanged cruciform section columns were built using six individual press-braked plain channels made of austenitic grade EN 1.4307 assembled back-to-back. Three different column lengths were tested – namely, short (600 mm), intermediate (1200 mm) and long (2400 mm) lengths, and two channel geometries were used in all tests – with cross-section depths of 200 mm and 100 mm. Tests were carried out under pure axial compression and with fixed end support conditions. Tests were repeated two times for each length. It was observed that the buckling patterns were affected both by the global slenderness and by the spacing between the fasteners. Stocky columns experienced local buckling of the individual channel sections. The plastic failure mechanism was dependent on the fasteners spacing. Intermediate slenderness columns were characterised by interaction between global torsional buckling and local buckling whereas more slender columns failed predominantly through torsional buckling. For the latter, the spacing between the fasteners had a minor influence on the ultimate capacity.

本文介绍了冷弯不锈钢十字形截面柱的屈曲和破坏行为的实验研究。双对称法兰十字形截面柱由6个独立的压制动平面通道组成,这些通道由奥氏体等级EN 1.4307背对背组装而成。测试了三种不同长度的柱子——即短(600毫米)、中间(1200毫米)和长(2400毫米)长度,所有测试中都使用了两种通道几何形状——横截面深度分别为200毫米和100毫米。试验是在纯轴向压缩和固定端支条件下进行的。每个长度重复测试两次。结果表明,屈曲模式受整体长细和紧固件间距的影响。粗壮柱经历了个别通道段的局部屈曲。塑性破坏机制与紧固件间距有关。中等细度柱的破坏主要是整体扭转屈曲和局部屈曲的相互作用,而较细度柱的破坏主要是扭转屈曲。对于后者,紧固件之间的间距对极限承载力的影响较小。


Improvement of interfacial thermal contact conductance and mechanical performance of metal-composite joint via controlling anchoring structures

Ziwei Feng, Xueyan Zhang, Chunlin Qin, Jianhui Su, Caiwang Tan, Hongyun Zhao, Bo Chen, Xiaoguo Song

doi:10.1016/j.tws.2024.111882

通过控制锚固结构改善金属复合材料接头的界面热接触导率和力学性能

This study discussed the interfacial heat conduction in depth during the laser welding of metal to composite by constructing rough morphologies adopting the laser ablation method. Results revealed the interface temperature was significantly elevated, reaching 375°C under a line spacing of 0.4mm, which was higher 45°C than without treatment. For one thing, the increased surface roughness reduced the heat loss and caused the heat concentration at the interface. For another thing, the expanded contact area improved the wettability and strengthened the physical adsorption, and the highest work of adhesion was increased to 49mJ/mm2, reaching 1.3 times of those without treatment. The thermal contact resistance was thus decreased, which was confirmed by finite element analysis. Finally, the maximum tensile-shear force and strength of joints were 4171N and 23MPa, which was 3.7 times and 3.9 times of those joints without treatment. Additionally, the fatigue life and anti-salty corrosion of joints were improved, providing an effective method for further application.

本文采用激光烧蚀的方法,对金属与复合材料激光焊接过程中的界面热传导进行了深入的研究。结果表明,在线间距为0.4mm时,界面温度显著升高,达到375℃,比未处理时高45℃。一方面,表面粗糙度的增加减少了热损失,引起了界面处的热集中。另一方面,接触面积的扩大提高了润湿性,增强了物理吸附,最高粘附功提高到49mJ/mm2,达到未处理的1.3倍。通过有限元分析证实了接触热阻的减小。最后,节理的最大拉剪力和强度分别为4171N和23MPa,分别是未处理节理的3.7倍和3.9倍。提高了接头的疲劳寿命和抗盐腐蚀性能,为进一步推广应用提供了有效的方法。


Coupled vibration analysis of partially liquid-filled cylindrical shells with internal horizontal plates

Songhao Chen, Yueyang Han, Xiang Zhu, Tianyun Li, Kexin Zhong

doi:10.1016/j.tws.2024.111884

内水平板部分充液圆柱壳的耦合振动分析

A semi-analytical method is proposed to analyze the coupling vibration characteristics of a partially liquid-filled cylindrical shell with an internal horizontal plate, considering the sloshing effect of the free liquid surface. Two coordinate systems are set at the midpoint of the free surface and the geometric center of the cylindrical shell's cross-section, respectively. The Flügge shell and Kirchhoff-love theories are adopted to establish the motion equations of the cylindrical shell and the plate on the structural coordinate system, respectively, in which the displacement functions are expressed with the wave propagation method. The liquid velocity potential functions are described in the symmetrical/anti-symmetrical forms based on the liquid coordinate system, which satisfies Laplace's equation. The coupling governing equations are deduced by the continuous conditions of force and displacement on the fluid-shell interface. After that, the coupling vibration responses can be solved. The accuracy of the present method is verified by the comparison with the finite element method. The influences of the structures’ parameters and liquid effect on the coupling system's free and forced vibration behaviors are discussed, and the sloshing behaviors of the internal fluid are also discussed under different parameters.

考虑自由液面晃动效应,提出了一种半解析法分析内水平板部分充液圆柱壳的耦合振动特性。在自由表面的中点和圆柱壳截面的几何中心分别设置两个坐标系。采用fl<s:1> gge壳理论和Kirchhoff-love理论分别建立了柱壳和板在结构坐标系上的运动方程,其中位移函数用波传播法表示。在满足拉普拉斯方程的液体坐标系下,以对称/反对称形式描述了液体的速度势函数。根据流壳界面上力和位移的连续条件,推导了耦合控制方程。然后求解耦合振动响应。通过与有限元法的比较,验证了该方法的准确性。讨论了结构参数和液体效应对耦合系统自由和强制振动特性的影响,并讨论了不同参数下内部流体的晃动特性。


High-frequency vibration analysis of panels under aerothermoelastic effects in supersonic airflow by an energy finite element method

Zhaolin Chen, Zhichun Yang, Yingsong Gu, Xiaochen Wang

doi:10.1016/j.tws.2024.111885

超声速气流中热弹性作用下面板高频振动的能量有限元分析

Vibration analysis of heated panels in supersonic airflow under aerothermoelastic effects has attracted wide attention, but the high-frequency vibration characteristics have not yet been thoroughly studied. A novel energy finite element method (EFEM), which can consider the aerothermoelastic effects, is proposed to investigate the high-frequency vibration response of heated panels in supersonic airflow. By separating the high-frequency response from the static or low-frequency aerothermoelastic response, a linearized high-frequency forced vibration equation is derived from the nonlinear motion equation of the panel. On this basis, the effects of in-plane and aerodynamic forces on the propagation properties of elastic waves in the panel are analyzed theoretically. By introducing these effects and the equivalent loss factors of elastic waves into EFEM theory, the energy density governing equation and the corresponding energy finite element model are established. Through numerical comparative studies, it is demonstrated that the proposed EFEM can well capture the aerothermoelastic effects and efficiently predict the high-frequency vibration response of heated panels in supersonic airflow. Particularly, the present EFEM is valid for panels in different aerothermoelastic states such as thermal buckling and flutter. In addition, the effects of aerothermoelasticity on the high-frequency vibration response are studied in detail, and the corresponding effect mechanism is revealed.

热弹性作用下加热板在超声速气流中的振动分析已引起广泛关注,但其高频振动特性尚未得到深入研究。提出了一种考虑气动热弹性效应的能量有限元方法来研究加热板在超声速气流中的高频振动响应。通过将面板的高频响应与静态或低频气动热弹性响应分离,从面板的非线性运动方程推导出线性化的高频强迫振动方程。在此基础上,从理论上分析了面内力和气动力对弹性波在面板中传播特性的影响。将弹性波的这些影响和等效损失因子引入有限元理论,建立了弹性波的能量密度控制方程和相应的能量有限元模型。数值对比研究表明,本文提出的有限元方法能够很好地捕捉到热弹性效应,并能有效地预测加热板在超声速气流中的高频振动响应。特别地,本有限元法适用于不同气动热弹性状态下的板,如热屈曲和颤振。此外,还详细研究了气动热弹性对高频振动响应的影响,揭示了其影响机理。



来源:复合材料力学仿真Composites FEM
ACTMechanicalSystem振动疲劳复合材料非线性ADSUG焊接理论材料控制试验
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首次发布时间:2024-11-14
最近编辑:8天前
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【新文速递】2024年3月29日复合材料SCI期刊最新文章

今日更新:Composite Structures 2 篇,Composites Part A: Applied Science and Manufacturing 1 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 4 篇Composite StructuresFree vibration analysis of composite beams and laminated reinforced panels by refined dynamic stiffness method and CUF-based component-wise theoryXiao Liu, Alfonso Pagani, Erasmo Carrera, Xiang Liudoi:10.1016/j.compstruct.2024.118058利用改进的动态刚度法和基于 CUF 的分量-全理对复合梁和层压加固板进行自由振动分析This paper presents a comprehensive analysis of the free vibration behavior of composite beams and laminated reinforced panels. Employing high-order theories with displacement variables only, the investigation combines dynamic stiffness method (DSM) and the Carrera unified formulation (CUF). The 3D displacement field can be expanded in the framework of CUF as any order of generic unknown variables over the cross-section, in the case of beam theories. Specifically, Lagrange expansions (LE) of cross-sectional displacement variables are considered, enabling the refinement modelling of complex cross-sections with different layers (layer-wise) and components (component-wise). The governing differential equations and natural boundary conditions are derived using the principle of virtual displacements. Subsequently, an exact dynamic stiffness matrix is developed by establishing a relationship between the amplitudes of harmonically varying loads and the corresponding responses. The Wittrick–Williams algorithm is employed to solve the transcendental eigenvalue problem resulting from this approach. The Lagrange-based CUF(LE)-DSM outperforms other polynomials (such as Taylor)-based CUF in analyzing composite structures, enabling detailed analysis with various geometries, lamination schemes and boundary conditions. It delivers accurate results in reinforced panel analysis, requiring only 13% of the DOFs compared to 3D FE models, thereby reducing computational costs significantly, as confirmed by comparative studies and validations.本文对复合梁和层压加固板的自由振动行为进行了全面分析。研究采用了仅包含位移变量的高阶理论,结合了动态刚度法(DSM)和卡雷拉统一公式(CUF)。在 CUF 框架内,三维位移场可作为横截面上的任意阶通用未知变量展开,以梁理论为例。具体地说,横截面位移变量的拉格朗日展开(LE)被考虑在内,从而能够对具有不同层(按层计算)和组件(按组件计算)的复杂横截面进行细化建模。利用虚拟位移原理推导出支配微分方程和自然边界条件。随后,通过建立谐波变化载荷振幅与相应响应之间的关系,开发出精确的动态刚度矩阵。该方法采用 Wittrick-Williams 算法来解决由此产生的超越特征值问题。在分析复合材料结构时,基于拉格朗日的 CUF(LE)-DSM 优于其他基于多项式(如泰勒)的 CUF,可对各种几何形状、层压方案和边界条件进行详细分析。与三维 FE 模型相比,它只需要 13% 的 DOFs,从而大大降低了计算成本。Short-term behavior of glass fiber-polymer composite bending-active elastica beam under service load applicationTara Habibi, Landolf Rhode-Barbarigos, Thomas Kellerdoi:10.1016/j.compstruct.2024.118080玻璃纤维-聚合物复合材料弯曲活性弹性梁在使用负荷下的短期行为Bending-active elastica beam is a structural configuration that is based on the elastic deformation of an initially straight beam. This deformation occurs when horizontal displacements are applied to a sliding support, causing the beam to bend into an arched shape. Previous research has focused on the stability of small-scale bending-active structures, thus not considering material strength, which is crucial in real-scale applications and structural design. This paper investigates the short-term structural behavior of bending-active elastica beams using pultruded glass fiber-polymer composite profiles, as used in real-scale structures. A series of short-term bending and service load application experiments were performed considering different bending degrees and loading scenarios. These results were used to validate finite element modeling. They demonstrated that steeper bent beams experience material failure, while shallower ones exhibit snap-through buckling. Material failure initiates on the tensile side of the beams, with cracks initiating at locations of maximum curvature. Higher bending degrees and symmetric loading result in higher maximum loads than lower bending degrees and asymmetric loading. A strain-based failure criterion, which can serve for structural design, is derived.弯曲活性弹性梁是一种基于初始直梁弹性变形的结构构造。当水平位移施加到滑动支撑上时,这种变形就会发生,从而导致梁弯曲成拱形。以往的研究主要关注小规模弯曲活动结构的稳定性,因此没有考虑材料强度,而材料强度在实际应用和结构设计中至关重要。本文研究了使用拉挤玻璃纤维-聚合物复合材料型材的弯曲活性弹性梁的短期结构行为。考虑到不同的弯曲度和加载情况,进行了一系列短期弯曲和使用荷载应用实验。这些结果用于验证有限元建模。实验结果表明,较陡的弯曲梁会出现材料失效,而较浅的弯曲梁则会出现快速屈曲。材料破坏始于梁的拉伸侧,裂缝始于最大曲率位置。与较低的弯曲度和不对称加载相比,较高的弯曲度和对称加载会产生较高的最大载荷。由此得出了一种基于应变的失效准则,可用于结构设计。Composites Part A: Applied Science and ManufacturingDesignable high-performance TPU foam strain sensors towards human-machine interfacesYuefeng Gu, Zhang Zhenghao, Feifan Fan, Lisi Wei, Tiancheng Wu, Dakai Wang, Qiuhong Lidoi:10.1016/j.compositesa.2024.108169 面向人机界面的可设计高性能热塑性聚氨酯泡沫应变传感器Flexible, breathable, and stable sensors were important in developing human–computer interaction systems and novel wearable devices. However, major challenges were still faced in two aspects, 1) high-performance strain sensors with a large sensing range, and 2) an interaction mode that is both convenient and efficient. Herein, we developed a thermoplastic polyurethane large-skeleton foam (TPU-LS foam) through a steam-induced method. The strain sensor comprised three layers of breathable foam, with CNTs/rGO TPU-LS foam as the inner layer and pure foam as the protective layer. PDMS/TiO2 was sprayed to create a UV-resistant and self-repairing coating, achieving a 66% melanin inhibition rate and a 91% repair rate. The sensor presented a wide work range over 100%, a high gauge factor of 637.8, and long-term durability. We trained machine learning frameworks to recognize different gestures and designed two types of human–computer interaction patterns, allowing users to operate apps with gestures.灵活、透气和稳定的传感器对于开发人机交互系统和新型可穿戴设备非常重要。然而,在两个方面仍面临重大挑战:1)传感范围大的高性能应变传感器;2)既方便又高效的交互模式。在此,我们通过蒸汽诱导法开发了一种热塑性聚氨酯大骨架泡沫(TPU-LS 泡沫)。应变传感器由三层透气泡沫组成,内层为 CNTs/rGO TPU-LS 泡沫,保护层为纯泡沫。喷涂的 PDMS/TiO2 涂层具有抗紫外线和自我修复功能,黑色素抑制率达到 66%,修复率达到 91%。传感器的工作范围超过 100%,测量系数高达 637.8,并具有长期耐用性。我们训练了机器学习框架来识别不同的手势,并设计了两种人机交互模式,让用户可以用手势操作应用程序。Composites Part B: EngineeringA comprehensive review on advancements, innovations and applications of 3D warp interlock fabrics and its composite materialsMulat Alubel Abtewdoi:10.1016/j.compositesb.2024.111395全面回顾三维经编互锁织物及其复合材料的进步、创新和应用Thanks to their superior performance including greater cohesion, good mechanical and delamination behaviors, and excellent formability properties, 3D warp interlock woven fabrics (3DWIFs) have emerged as promising fibrous reinforcement structure for composite material. The current paper explores the innovations, advanced developments, and varied applications of 3DWIFs and its composites. Initially, the paper discusses the fabric&#39;s versatile potential, revealing its exceptional structural integrity, formability, manufacturing techniques, broad spectrum of applications and other parameters compared to conventional two-dimensional woven fabric reinforcements. Furthermore, the potential benefits and challenges of the 3DWIFs and its composite materials are explained to highlight their prospects in current and future industrial applications. Subsequently, the paper further explores the reinforcement&#39;s distinctive structural characteristics emphasizing its classifications and designing techniques. The discussion extends to the extensive and versatile applications of 3DWIFs and its composites across diverse sectors, including defence and security, the automotive and aerospace industry, and the civil and architectural sectors. By synthesizing and critically analyzing the existing research, this paper will serve as a valuable resource, enlightening the 3DWIF&#39;s present status and projecting its promising prospects both as dry fabric and composite reinforcing material for diverse industrial applications.三维经纱交错编织物(3DWIF)具有更高的内聚力、良好的机械和分层行为以及优异的可成形性等优越性能,因此已成为复合材料中极具前景的纤维增强结构。本文探讨了 3DWIF 及其复合材料的创新、先进发展和各种应用。首先,本文讨论了这种织物的多功能潜力,揭示了与传统二维编织物加固材料相比,其卓越的结构完整性、可成形性、制造技术、广泛的应用范围和其他参数。此外,还解释了 3DWIF 及其复合材料的潜在优势和挑战,以突出其在当前和未来工业应用中的前景。随后,论文进一步探讨了加固材料的独特结构特征,强调了其分类和设计技术。讨论延伸到 3DWIFs 及其复合材料在不同领域的广泛和多用途应用,包括国防和安全、汽车和航空航天工业以及民用和建筑领域。通过对现有研究的综合和批判性分析,本文将成为一份宝贵的资料,揭示 3DWIF 的现状,并预测其作为干法织物和复合材料在不同工业应用领域的广阔前景。Composites Science and TechnologyContinuous additive manufacturing of hemp yarn-reinforced biocomposites with improved impregnation methodGeoffrey Ginoux, Xikun Wu, Chaimae Laqraa, Damien Soulat, Joseph Paux, Manuela Ferreira, L.A.B.A.N.I.E.H. Ahmad-Rashed, Samir Allaouidoi:10.1016/j.compscitech.2024.110561 用改进的浸渍方法连续添加制造麻纱增强生物复合材料This study was motivated by the development of new additively manufactured bio-based materials with high performance. Hemp yarn was used in continuous material extrusion additive manufacturing to produce novel hemp yarn-reinforced biocomposites. The hemp yarn was compared to an original hemp/poly(lactic acid) hybrid yarn prepared by commingling before printing as an improved impregnation method. In X-ray micro-computed tomography, the hybrid yarn-based biocomposite exhibited a higher impregnation rate accompanied by a reduced void content, more aligned fibers, and a more homogeneous distribution of the different constituents, resulting in significantly higher mechanical properties during tensile loading with a more brittle behavior compared to the additively manufactured biocomposite based on pure hemp yarn. In addition, superior mechanical performance was obtained while having lower fiber fraction with the use of hybrid yarns, raising awareness about the importance of improving the impregnation of the plant fibers as well as the fiber volume fraction. This original preparation method can provide bio-based materials with enhanced quality and performance, close to those obtained with conventional manufacturing techniques, while making the most of additive manufacturing for sustainable, lightweight, and high-end applications in health or aerospace.这项研究的动机是开发新的高性能生物基添加制造材料。麻纱被用于连续材料挤压添加制造,以生产新型麻纱增强生物复合材料。作为一种改进的浸渍方法,大 麻纱线与原始的大 麻/聚(乳酸)混合纱线进行了比较。在 X 射线显微计算机断层扫描中,基于混合纱线的生物复合材料表现出更高的浸渍率,同时空隙含量降低,纤维更整齐,不同成分的分布更均匀,因此与基于纯大 麻纱线的添加剂制造的生物复合材料相比,在拉伸加载过程中机械性能显著提高,行为更脆。此外,在使用混合纱线时,虽然纤维分数较低,但却获得了优异的机械性能,这让人们意识到提高植物纤维浸渍度和纤维体积分数的重要性。这种独创的制备方法可以提供质量和性能更高的生物基材料,接近传统制造技术所获得的材料,同时充分利用增材制造技术,实现可持续、轻质和高端的健康或航空航天应用。Recycled rubber wastes-based polymer composites with flame retardancy and electrical conductivity: Rational design, modeling and optimizationPaulina Wiśniewska, Natalia A. Wójcik, Paulina Kosmela, Jacek Ryl, Robert Bogdanowicz, Henri Vahabi, Alireza Shadman, Krzysztof Formela, Mohammad Reza Saebdoi:10.1016/j.compscitech.2024.110563 具有阻燃性和导电性的回收橡胶废料基聚合物复合材料:合理设计、建模和优化Polymer recycling techniques experience a maturity period of design and application. Rubbers comprise a high proportion of polymer wastes, highly flammable and impossible to re-melt. Polymer composites based on ground tire rubber (GTR) and ethylene-vinyl acetate copolymer (EVA) containing carbon black (CB) (1–50 phr), with variable EVA/GTR weight composition (10/90, 25/75, 50/50, 75/25 and 90/10), and processing temperature (Low: 100 °C and High: 200 °C) were designed applying Design of Experiments (DOE) approach of Optimal Design. The properties and performance features were experimentally evaluated. The tensile strength (TS) and elongation at break (EB) were optimized using Desirability Function (DF) approach. A wide fluidity window (Labeled POOR, GOOD, and EXCELLENT) and mechanical properties were observed. Overall, higher values of EB were assigned to samples processed at 200 °C. Cubic regression modeling and DF optimization of TS and EB indicated unlikely that one expect a TS ≥ 3 MPa, while EB values more than 500% were likely regardless of CB content for EVA-rich composites. The electrical properties of CB/EVA/GTR samples were examined by impedance spectroscopy technique. An interesting relationship was observed between the DC conductivity and the EVA/GTR ratio and processing temperature. GTR-rich samples showed much higher conductivity than EVA-dominated samples, attributed to the presence of CB in the rubber waste, which, together with the added CB, was able to create conduction paths for the transported electrons. Higher processing temperature of 200 °C improved dispersion of the added CB, i.e. a more even distribution of the conductive phase in the matrix. The uniform and evenly dispersed domains of particles were detected by SEM images for highly CB loaded composites. Surprisingly, 50/50 EVA/GTR composites were resilient against flame, while thermally stable ones in TGA measurements were highly CB loaded ones.聚合物回收技术在设计和应用方面已进入成熟期。橡胶在聚合物废物中占很大比例,极易燃烧且无法再熔化。应用最优设计的实验设计(DOE)方法,设计了基于轮胎橡胶(GTR)和含炭黑(CB)(1-50 phr)的乙烯-醋酸乙烯共聚物(EVA)的聚合物复合材料,EVA/GTR 的重量组成可变(10/90、25/75、50/50、75/25 和 90/10),加工温度可变(低:100 °C 和高:200 °C)。实验评估了这些材料的特性和性能特征。拉伸强度(TS)和断裂伸长率(EB)采用可取函数法(DF)进行了优化。观察到了较宽的流动性窗口(标记为 &quot;差&quot;、&quot;好 &quot;和 &quot;优&quot;)和机械性能。总体而言,在 200 °C 下加工的样品 EB 值较高。TS 和 EB 的立方回归建模和 DF 优化表明,TS ≥ 3 MPa 的可能性不大,而对于富含 EVA 的复合材料,无论 CB 含量如何,EB 值都可能超过 500%。通过阻抗光谱技术检测了 CB/EVA/GTR 样品的电特性。观察到直流电导率与 EVA/GTR 比率和加工温度之间存在有趣的关系。富含 GTR 的样品比以 EVA 为主的样品显示出更高的导电率,这归因于橡胶废料中含有 CB,CB 和添加的 CB 能够为传输的电子创建传导路径。200 °C 的较高加工温度改善了添加的 CB 的分散性,即导电相在基体中的分布更加均匀。通过扫描电子显微镜图像,可以检测到高 CB 负载复合材料的颗粒域均匀且分散一致。令人惊讶的是,50/50 EVA/GTR 复合材料具有抗燃性,而在 TGA 测量中热稳定性较好的是高 CB 含量的复合材料。Quasi-static crush response of lightweight sandwich composite tubes fabricated via newly designed internal thermal expansion techniqueYunfei Peng, Maojun Li, Xujing Yang, Jinzhi Li, Chenfeng Xiongdoi:10.1016/j.compscitech.2024.110574 通过新设计的内部热膨胀技术制造的轻质夹层复合管的准静态挤压响应Different from conventional unidirectional outward-inward forming methods, this study employs a multidirectional internal expansion shaping approach to fabricate lightweight sandwich composite tubes. Integrating carbon fiber reinforced polymer (CFRP), thermal expansion foam and polymethacrylimide (PMI) foam, the sandwich composite tubes demonstrate adaptability in terms of material properties as validated through several experimental trials. The one-step molding process eliminates the requirements for subsequent structural assembly and bonding, while ensuring adhesion between diverse material components. The sandwich composite tubes exhibit superior impact resistance, showcasing a stable progressive crushing failure. The energy absorption mechanism shifts from single CFRP damage to a multi-material composite energy absorption mode. The specific energy absorption (SEA) value of designed sandwich composite tube is up to 102 J/g. The sandwich composite tubes fabricated in this study hold promising applications in advanced vehicle/aerospace lightweighting and crashworthiness safety.与传统的单向外向内成型方法不同,本研究采用多向内胀成型方法制造轻质夹层复合管。这种夹层复合材料管融合了碳纤维增强聚合物(CFRP)、热膨胀泡沫和聚甲基丙烯酰亚胺(PMI)泡沫,其材料性能的适应性经过多次实验验证。一步成型工艺省去了后续的结构组装和粘合要求,同时确保了不同材料成分之间的粘合性。夹层复合材料管表现出卓越的抗冲击性能,呈现出稳定的渐进式破碎失效。能量吸收机制从单一的 CFRP 损坏转变为多材料复合材料能量吸收模式。设计的夹层复合管的比能量吸收(SEA)值高达 102 J/g。本研究中制造的夹层复合管在先进汽车/航空航天轻量化和防撞安全方面具有广阔的应用前景。Robust and wear-durable coating based on halloysite nanotubes/polymer composite for passive daytime radiative coolingXinyuan Zhou, Yuqian Xu, Di Zhang, Ming Huang, Mingxian Liudoi:10.1016/j.compscitech.2024.110566 基于哈洛石纳米管/聚合物复合材料的坚固耐磨涂层,用于日间被动辐射制冷Passive daytime radiative cooling (PDRC) is an efficient strategy to achieve cooling through spectrally selective emission and high solar spectrum reflection. Current preparation strategies for PDRC materials mainly involve doping inorganic micro-nanoparticles into polymers, but their solar reflectance is usually insufficient. Here, we designed a super-white inorganic coating on different substrates based on natural halloysite nanotubes (HNTs) through the doctor blade method. Polyvinyl alcohol (PVA) and water-based acrylic resin (AR) were introduced to increase the adhesion for obtaining robust inorganic coating. HNTs/PVA/AR composite coating shows excellent water resistance, wear resistance, and environmental tolerance, which is mainly due to the strong interfacial interactions between HNTs, PVA, and AR. Compared with the uncoated transparent plastic, the coated plastic exhibits a super-white appearance (whiteness of ∼95%) and maximum solar reflectance of ∼97%. The maximum temperature difference of the HNTs/PVA/AR coated and pristine copper sheet is15 °C under simulated sunlight. The PDRC property is related to the high surface roughness of the coating composed of disordered high-aspect ratio nanotubes and the high whiteness of the raw halloysite materials. The composite coating can tolerate pH from 1–13, temperature change (−60∼250 °C), and different salt environments. The composite coating increases thermal stability, flame retardancy, and giving protective effect of dye against UV degradation. In addition, the HNTs/PVA/AR coated plastic as packaging materials can maintain good freshness of different fruits under strong solar irradiation. The robust HNTs/PVA/AR composite coating with high PDRC properties shows promising application in food packaging, building energy conservation, metal anticorrosive coating, and sunscreen products.被动日间辐射冷却(PDRC)是一种通过光谱选择性发射和高太阳光谱反射实现冷却的有效策略。目前的 PDRC 材料制备策略主要是在聚合物中掺入无机微纳米粒子,但其太阳反射率通常不足。在此,我们通过刮刀法在不同基底上设计了一种基于天然埃洛石纳米管(HNTs)的超白无机涂层。为了获得坚固的无机涂层,我们引入了聚乙烯醇(PVA)和水性丙烯酸树脂(AR)来增加附着力。HNTs/PVA/AR 复合涂层具有优异的耐水性、耐磨性和环境耐受性,这主要归功于 HNTs、PVA 和 AR 之间的强界面相互作用。与未涂覆的透明塑料相比,涂覆后的塑料外观超白(白度达 95%),最大太阳反射率达 97%。在模拟阳光下,HNTs/PVA/AR 涂层铜板与原始铜板的最大温差为 15 °C。PDRC 特性与无序高谱系比纳米管组成的涂层的高表面粗糙度和埃洛石原料的高白度有关。复合涂层可耐受 1-13 的 pH 值、温度变化(-60∼250 °C)和不同的盐环境。复合涂层提高了热稳定性和阻燃性,并使染料具有抗紫外线降解的保护作用。此外,HNTs/PVA/AR 涂层塑料作为包装材料还能在强烈的太阳光照射下保持不同水果的新鲜度。具有高 PDRC 特性的坚固 HNTs/PVA/AR 复合涂层在食品包装、建筑节能、金属防腐涂料和防晒产品方面具有广阔的应用前景。来源:复合材料力学仿真Composites FEM

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