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【新文速递】2023年11月21日复合材料SCI期刊最新文章

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今日更新:Composites Part A: Applied Science and Manufacturing 3 篇,Composites Science and Technology 2 篇

Composites Part A: Applied Science and Manufacturing

Enhancing mechanical properties and thermal conductivity in polymer bonded explosives by multi-scale surface modification of carbon fibers

He Guansong, Wang Peng, Zhong Ruolei, Li Xin, Yin Huamo, Chen Jie, Liu Shijun, Yang Zhijian

doi:10.1016/j.compositesa.2023.107918

通过对碳纤维进行多尺度表面改性,提高聚合物粘合炸药的机械性能和导热性能

Poor interfacial interaction and strength largely restrict the overall performance and practical application of carbon fibers (CFs) reinforced composites. The favorable interfacial properties were the key to realize superior mechanical properties in composites. Herein, we reported a novel multi-scale surface modification strategy of CFs to strengthen interfacial properties. Based on chemical oxidation treatment, the surface of CFs was further in situ grafted by a crosslinked high-strength polymer network consisting of aromatic diisocyanate, graphene oxide (GO) and polyethylenen glycol (PEG), which significantly improved the interfacial bonding and mechanical strength of interface layer itself. Benefitting from this multi-scale surface treatment, a high-efficiency mechanical enhancement of polymer bonded explosives (PBX) was achieved. With only 0.3 wt% fiber content, the maximum tensile and compressive strength PBX composites were both significantly improved, which were 63% and 39% higher than those of pure PBX, respectively. Meanwhile, the thermal conductivity was also enhanced, yielding a significant synergistic enhancement effect. The interface failure mechanism of the composite under stress was clarified by the fracture morphology characterization. This study sheds a light for exploring novel surface modification and has the potential application in in high performance polymer composites.

界面相互作用和强度差在很大程度上限制了碳纤维(CFs)增强复合材料的整体性能和实际应用。良好的界面性能是实现复合材料优异机械性能的关键。在此,我们报告了一种新型的多尺度碳纤维表面改性策略,以增强界面性能。在化学氧化处理的基础上,进一步在 CF 表面原位接枝由芳香族二异氰酸酯、氧化石墨烯(GO)和聚乙二醇(PEG)组成的交联高强度聚合物网络,从而显著提高了界面层本身的界面结合力和机械强度。得益于这种多尺度表面处理,实现了聚合物结合炸药(PBX)的高效机械增强。在纤维含量仅为 0.3 wt% 的情况下,PBX 复合材料的最大拉伸强度和抗压强度都得到了显著提高,分别比纯 PBX 复合材料高出 63% 和 39%。同时,热导率也得到了提高,产生了明显的协同增强效应。通过断口形貌表征,阐明了复合材料在应力作用下的界面失效机理。这项研究为探索新型表面改性提供了启示,具有在高性能聚合物复合材料中应用的潜力。


Shape-memory polyurethane elastomer originated from waste PET plastic and their composites with carbon nanotube for sensitive and stretchable strain sensor

Zhou Xing, Wang Guosheng, Li Dexiang, Wang Qi, Zhu Keming, Hao Yaya, Xu Yueyang, Li Neng

doi:10.1016/j.compositesa.2023.107920

 

利用废 PET 塑料制成的形状记忆聚氨酯弹性体及其与碳纳米管的复合材料,用于灵敏且可拉伸的应变传感器

Chemical recycling of polyethylene terephthalate (PET) bottles is prospective for reducing waste plastics. The transformation of waste PET into valuable composites in high efficiency still remains a formidable challenge. Here we report the synthesis of polyurethane elastomer (PUE) by using the degraded products from waste PET via one-pot chain extended process. Then, the composites composed of PUE as substrate with carbon nanotubes as fillers are applied in fabricating stretchable strain sensor. The results show that the degraded product was successfully introduced into the polyurethane chains. The PUE chains showed disordered stacking as the degraded product content increased, with the modulus and elongation at break were up to 763.9 %. The composites assembled strain sensors exhibited stable sensing performance and excellent durability after 1000 cycles at 20 % tensile strain. This may supply a path to efficiently recycle waste PET plastic into valuable and functional composites, and even devices.

聚对苯二甲酸乙二酯(PET)瓶的化学回收利用在减少废塑料方面前景广阔。如何高效地将废弃 PET 转变为有价值的复合材料仍是一项艰巨的挑战。在此,我们报告了利用废弃 PET 的降解产物,通过一锅扩链工艺合成聚氨酯弹性体(PUE)的过程。然后,以聚氨酯弹性体为基材,碳纳米管为填料组成的复合材料被应用于制造可拉伸应变传感器。结果表明,降解产物被成功引入到聚氨酯链中。随着降解产物含量的增加,聚氨酯链出现了无序堆叠,模量和断裂伸长率高达 763.9%。组装应变传感器的复合材料在 20% 拉伸应变条件下循环使用 1000 次后,显示出稳定的传感性能和出色的耐用性。这为将废弃 PET 塑料有效回收利用为有价值的功能性复合材料甚至设备提供了一条途径。


The simultaneously achieved high permittivity and low loss in tri-layer composites via introducing negative permittivity layer

Song Xiaoting, Zhang Zidong, Fan Guohua, Liu Yao, Fan Runhua

doi:10.1016/j.compositesa.2023.107921

通过引入负介电常数层,在三层复合材料中同时实现高介电常数和低损耗

Dielectric composites with excellent power densities have garnered significant attentions in electrical systems and pulsed energy storage. However, the low permittivity and high dielectric loss are greatly limit their applications. Herein, we present a novel approach involving tri-layer composites, where a middle negative-έ layer is sandwiched between outer positive-έ layers. This design aims to realize the balance of comprehensive performances by the interfacial polarization and synergistic effect between positive and negative-έ layers. Amazingly, the composite with content 3-5-3 with the thickness ratio of 1:20:1 shows remarkable permittivity of 679 coupled with a low loss tangent of 0.017 @ 10kHz, which is approximately 141 times higher than PI matrix with 4.8 of permittivity. Remarkably, the composite with content 3-5-3 (1:1:1) exhibited an improved Ud and high η of 1.35 J/cm3 and 94.5%, respectively. This work presents a new class of tri-layer composites with negative-έ layer, whose design method is applicable in high-property dielectric composites.

具有出色功率密度的介电复合材料在电气系统和脉冲储能领域备受关注。然而,低介电常数和高介电损耗极大地限制了它们的应用。在此,我们提出了一种涉及三层复合材料的新方法,即在外层正έ层之间夹入中间负έ层。这种设计旨在通过界面极化和正负έ层之间的协同效应实现综合性能的平衡。令人惊奇的是,厚度比为 1:20:1 且含量为 3-5-3 的复合材料显示出 679 的显著介电常数和 0.017 @ 10kHz 的低损耗正切,这比介电常数为 4.8 的 PI 基体高出约 141 倍。值得注意的是,3-5-3(1:1:1)含量的复合材料显示出更高的 Ud 值和更高的η 值,分别为 1.35 J/cm3 和 94.5%。这项研究提出了一种新型负έ层三层复合材料,其设计方法适用于高特性介电复合材料。


Composites Science and Technology

Interfacial reinforcement of carbon fiber composites through a chlorinated aramid nanofiber interphase

Mamolo Steven U., Sodano Henry A.

doi:10.1016/j.compscitech.2023.110351

 

通过氯化芳纶纳米纤维间相实现碳纤维复合材料的界面加固

Carbon fiber-reinforced polymers (CFRPs) rely on a strong interfacial bond between the reinforcing fibers and polymeric matrix to yield the high strength and toughness expected by a composite material. Poor interfacial strength leads to sub-optimal load transfer and introduces stress concentrations, which can reduce overall performance and result in catastrophic failure. Aramid nanofibers (ANFs) have shown significant promise for interfacial reinforcement in polymeric composite systems due to their high tensile strength, large specific surface area, and abundant polar functional groups. However, due to the chemically inert nature of carbon fibers, ANFs do not readily bond to their surface – thus limiting their application to CFRPs. In this work, we demonstrate that chlorination of ANFs and oxygen plasma treatment of carbon fibers enables the formation of a chlorinated ANF (Cl-ANF) interphase through chemical and physical adsorption using a simple dip-coating process, while fully preserving the tensile strength of the carbon fibers. The Cl-ANF interphase yielded a 79.8 % increase in interfacial shear strength and a 33.7 % increase in short beam strength. By enhancing the interfacial bond between fiber and matrix without degradation of the fiber's tensile strength, this method provides a rapid and reliable process to improve the mechanical properties of CFRP composites.

碳纤维增强聚合物(CFRP)依靠增强纤维与聚合物基体之间牢固的界面结合力来实现复合材料所期望的高强度和韧性。界面强度差会导致载荷传递效果不理想,并引起应力集中,从而降低整体性能并导致灾难性故障。芳纶纳米纤维(ANFs)具有拉伸强度高、比表面积大和极性官能团丰富等特点,因此在聚合物复合材料体系中的界面加固方面大有可为。然而,由于碳纤维的化学惰性,ANFs 不易与碳纤维表面结合,因此限制了其在 CFRP 中的应用。在这项工作中,我们证明了对 ANFs 进行氯化处理和对碳纤维进行氧等离子体处理后,可通过简单的浸涂工艺,利用化学和物理吸附作用形成氯化 ANF(Cl-ANF)相,同时完全保持碳纤维的抗拉强度。Cl-ANF 中间相使界面剪切强度提高了 79.8%,短束强度提高了 33.7%。通过增强纤维与基体之间的界面结合力而不降低纤维的抗拉强度,这种方法为提高 CFRP 复合材料的机械性能提供了一种快速可靠的工艺。


Optimizing energy storage density of the multi–layer composite of poly(vinylidene fluoride) and nano–Ni plated CaCu3Ti4O12 with an ultralow filling content

Gao Liang, Zhang Yuting, Xiao Qianqian, Gao Zhengwu, Wang Xuan

doi:10.1016/j.compscitech.2023.110353

 

优化超低填充物含量的聚偏氟乙烯和纳米镍镀层 CaCu3Ti4O12 多层复合材料的储能密度

Surface modification of nanoceramics with high dielectric constant can increase dielectric constant of polymer composites voiding excessive dielectric loss, however, low discharged energy density (Ud) of composites at a low loading limits potential applications in high–energy–storage devices under low electric field. Herein, Ni–plated CaCu3Ti4O12 nanoparticle (CCTO@Ni) is used to improve the electric properties of the poly(vinylidene fluoride) monolayer composites (C/PVDF), and an ultralow loading of 0.5 vol% promotes the largest Ud of 2.53 J/cm3 at 230 MV/m, resulting from MWS interface polarization and Coulomb barrier effect included by CCTO@Ni fillers, which is used to further prepare three kinds of multi–layer structured C/PVDF composites by solution casting layer by layer. Comprehensive testing shows that the PVDF–C/PVDF–PVDF–C/PVDF–PVDF five–layer film (P–C–P–C–P) enhances the dielectric constant and breakdown strength to contribute the maximal Ud of 6.65 J/cm3 at 297.8 MV/m, which is 118% larger than that of pure PVDF. Above excellent characteristics are attributed to the interface polarization of the middle C/PVDF layer and the alleviating and blocking effect of the middle and outer PVDF layers, which are clarified in depth by the finite element simulation and enhanced breakdown model.

对具有高介电常数的纳米陶瓷进行表面改性可以提高聚合物复合材料的介电常数,从而避免过多的介电损耗,然而,复合材料在低负载时的低放电能量密度(Ud)限制了其在低电场下高能量存储设备中的潜在应用。在本文中,镀镍的 CaCu3Ti4O12 纳米粒子(CCTO@Ni)被用来改善聚偏氟乙烯单层复合材料(C/PVDF)的电性能,0.5 vol% 的超低负载可使其在 230 MV 下的最大放电能量密度达到 2.53 J/cm3。 CCTO@Ni 填料在 230 MV/m 时产生的 MWS 界面极化和库仑势垒效应,进一步通过逐层溶液浇注制备了三种多层结构的 C/PVDF 复合材料。综合测试结果表明,PVDF-C/PVDF-PVDF-C/PVDF-PVDF 五层薄膜(P-C-P-C-P)提高了介电常数和击穿强度,在 297.8 MV/m 时的最大 Ud 为 6.65 J/cm3,比纯 PVDF 大 118%。上述优异特性归功于中间 C/PVDF 层的界面极化以及中间和外层 PVDF 层的缓解和阻挡作用,有限元模拟和增强击穿模型深入阐明了这一点。



来源:复合材料力学仿真Composites FEM
ACTMechanicalSystem断裂复合材料化学ADSUG电场材料储能多尺度电气
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首次发布时间:2024-11-03
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【新文速递】2023年11月5日固体力学SCI期刊最新文章

今日更新:International Journal of Solids and Structures 1 篇,Journal of the Mechanics and Physics of Solids 1 篇,Mechanics of Materials 1 篇,Thin-Walled Structures 7 篇International Journal of Solids and StructuresMechanics of Assembling Two-Dimensional Materials on a Solid Substrate by Droplet DryingChen Ziyu, Liu Qingchang, Xu Baoxingdoi:10.1016/j.ijsolstr.2023.112554通过液滴干燥在固体基底上组装二维材料的力学原理Assembly of two-dimensional (2D) nanomaterials by droplet drying offers a straightforward and low-cost route to obtain their bulk forms for widespread applications in manufacturing and printing of functional structures and devices. However, unlike rigid nanoparticles that usually do not experience mechanical deformation, 2D nanomaterials are easily deformed and folded during assembly by evaporative drying, and traditional assembly theory that can address these fundamental deformation mechanisms is currently lacking. In the present study, we have developed an energy-based rotational spring-mechanical slider mechanics model to describe the mechanical deformation and assembly of 2D material graphene on a solid substrate during the evaporation of its droplet solution. In the development of theory, the mechanical folding deformation of 2D material graphene itself is modeled by the rotational spring, and the folding-induced interior interactions of graphene itself and its assembly interactions with neighboring ones and solid substrate all due to van der Waal force are modeled by the mechanical sliders. The surface wettability of substrate and the evaporative modes of droplet on substrate including constant contact angle (CCA), constant contact radius (CCR), and their combination are also incorporated into the mechanics model. In parallel, large-scale molecular dynamics (MD) simulations with the development of coarse-grained model of 2D graphene and its virtual force field interaction with liquid is performed and show remarkable agreement with theoretical predictions on both assembly patterns and dimensional sizes. The effect of graphene size and its interaction strength with substrate on assembly is also elucidated. This work helps understand fundamental science in assembly of mechanically deformable nanomaterials by solution drying, and also provides immediate guidance to ink-based printing techniques for manufacturing deformable nanomaterials-enabled devices with controlled patterns on substrates.通过液滴干燥法组装二维(2D)纳米材料为获得其块状形态提供了一条直接而低成本的途径,可广泛应用于功能结构和设备的制造和打印。然而,与通常不会发生机械变形的刚性纳米颗粒不同,二维纳米材料在通过蒸发干燥进行组装的过程中很容易发生变形和折叠,而目前还缺乏能够解决这些基本变形机制的传统组装理论。在本研究中,我们建立了一个基于能量的旋转弹簧-机械滑块力学模型来描述二维材料石墨烯在其液滴溶液蒸发过程中在固体基底上的机械变形和组装。在理论发展过程中,二维材料石墨烯本身的机械折叠变形由旋转弹簧建模,而石墨烯本身的折叠引起的内部相互作用及其与相邻石墨烯和固体基底之间由于范德华力引起的组装相互作用则由机械滑块建模。基底的表面润湿性和液滴在基底上的蒸发模式(包括恒定接触角 (CCA)、恒定接触半径 (CCR) 及其组合)也被纳入力学模型。与此同时,还进行了大规模分子动力学(MD)模拟,建立了二维石墨烯的粗粒度模型及其与液体相互作用的虚拟力场,结果表明其组装模式和尺寸大小与理论预测非常吻合。研究还阐明了石墨烯尺寸及其与基底相互作用强度对组装的影响。这项工作有助于理解通过溶液干燥组装机械可变形纳米材料的基础科学,也为基于油墨的印刷技术在基底上制造具有可控图案的可变形纳米材料设备提供了直接指导。Journal of the Mechanics and Physics of SolidsElastic energy and polarization transport through spatial modulationCheng Wen, Zhang Hongkuan, Wei Yu, Wang Kun, Hu Gengkaidoi:10.1016/j.jmps.2023.105475通过空间调制实现弹性能量和偏振传输Thouless pumping, a specific type of quantum Hall effect, enables topological transport of energy through internal pathways by modulating adiabatically the Hamiltonian of a system. This intriguing phenomenon has been mostly observed in discrete waveguide systems. In this study, we propose a similar phenomenon for a continuous in-plane elastic system and explore its topological properties, including vibrational spectra and localized modes. This pumping is achieved by directly incorporating spatial modulation on material elasticity. We illustrate that a given polarization of elastic waves can be transported and converted along customized paths through phase modulation of elastic tensor. This transport is topologically protected, allowing precise and robust control over elastic wave propagation. To actualize this phenomenon, a family of lattice microstructures, termed as pentamode materials, is specifically engineered to accommodate the distribution of elastic tensor. The topological properties of the modulated lattice are found to agree well with the continuum model. The approach offers an alternative and promising strategy for effectively manipulating elastic waves, paving the way for various applications in elastic waveguiding and wave-based technologies.无苏泵浦是量子霍尔效应的一种特殊类型,它通过对系统的哈密尔顿进行绝热调制,使能量通过内部路径进行拓扑传输。这种有趣的现象主要是在离散波导系统中观察到的。在本研究中,我们提出了连续面内弹性系统的类似现象,并探索了其拓扑特性,包括振动光谱和局部模式。这种抽运是通过直接对材料弹性进行空间调制来实现的。我们说明,通过弹性张量的相位调制,给定极化的弹性波可以沿着定制路径传输和转换。这种传输受拓扑保护,可对弹性波的传播进行精确而稳健的控制。为了实现这一现象,我们专门设计了一系列被称为五模材料的晶格微结构,以适应弹性张量的分布。研究发现,调制晶格的拓扑特性与连续模型十分吻合。这种方法为有效操纵弹性波提供了另一种有前途的策略,为弹性波导和基于波的技术的各种应用铺平了道路。Mechanics of MaterialsCompression of filled, open-cell, 3D-printed Kelvin latticesCarlsson J., Kuswoyo A., Shaikeea A., Fleck N.A.doi:10.1016/j.mechmat.2023.104851压缩填充式开孔 3D 打印开尔文晶格The sensitivity of compressive strength of a polymeric Kelvin lattice to the presence of an epoxy core has been investigated both experimentally and numerically. Crush bands develop in the empty lattice, with large oscillations in load due to geometric softening and the sequential fracture of successive layers of struts. In contrast, the epoxy core has a sufficiently high modulus and strength that outward lateral flow of the epoxy through the open-cell lattice is negligible: the boundary layer, wherein migration of epoxy occurs through the lattice, extends less than one cell size from the surface of the specimen. The epoxy core supports the struts and stabilises the bulk macroscopic response against crush band formation. Finite element analysis of periodic unit cells show that the presence of an almost incompressible epoxy core changes the deformation mode of the lattice from one that is close to uniaxial straining to an isochoric mode. However, both the compressible collapse mode of the empty lattice and the isochoric deformation mode of the filled lattice are bending-dominated. At finite strain, the observed macroscopic strength of the filled lattice is degraded by bending failure of the struts and by tensile cracking of the adjacent core; the failure location is at a particular subset of the nodes of the lattice. Microcrack coalescence leads to the formation of a series of vertical fissures in the specimen.我们通过实验和数值计算研究了聚合物开尔文晶格的抗压强度对环氧树脂芯材存在的敏感性。在空网格中会产生挤压带,由于几何软化和连续层支柱的相继断裂,载荷会产生较大的振荡。相比之下,环氧树脂芯具有足够高的模量和强度,因此环氧树脂通过开孔晶格的外侧流动可以忽略不计:环氧树脂通过晶格发生迁移的边界层从试样表面延伸不到一个晶格大小。环氧树脂芯支撑着支杆,并稳定了整体宏观响应,防止挤压带的形成。周期性单元格的有限元分析表明,几乎不可压缩的环氧树脂内核的存在改变了晶格的变形模式,从接近单轴应变模式变为等速模式。然而,空晶格的可压缩塌缩模式和填充晶格的等速变形模式都以弯曲为主。在有限应变条件下,观察到的填充晶格的宏观强度因支柱的弯曲失效和相邻核心的拉伸开裂而降低;失效位置位于晶格节点的特定子集。微裂缝凝聚导致试样形成一系列垂直裂缝。Thin-Walled StructuresA semi-analytical method for vibration localization of plates integrated with low-frequency plate-type resonatorsXue Jian, Zhang Weiwei, Wu Jing, Wang Chao, Ma Hongweidoi:10.1016/j.tws.2023.111332低频板式谐振器集成板振动定位的半解析方法A plate-type local resonator with varying free boundaries is integrated within the plate to transform the initial low-order global vibration modes into localized vibration modes. A novel semi-analytical method is proposed to analyze the free vibration of the plate with discontinuities in thickness and displacement. The host plate and the resonator are modeled separately and coupled by the condition of displacement compatibility, based on the geometry configuration. A set of local admissible functions, consisting of global and local parts in the resonator domain, is proposed to describe the vibration localization and displacement discontinuity. The Ritz method with the proposed admissible functions is employed to investigate the effect of geometry parameters and boundary conditions on the vibration characteristics of the plates. The lack of orthogonality between the global and localized modes is determined using the analytic mode functions obtained by the proposed method and can be altered by the free boundary conditions of the resonator. The results demonstrate that by applying free boundary conditions to a resonator, the low-order localized vibration frequencies can be significantly reduced by up to 90%, with negligible effect on low-order global frequencies. An original and exciting finding is that the global modes can be assimilated by the corresponding localized vibration modes with close frequencies.在板内集成了一个具有变化自由边界的板式局部谐振器,以将初始低阶全局振动模式转化为局部振动模式。本文提出了一种新颖的半分析方法,用于分析厚度和位移不连续的板自由振动。主机板和共振器被分开建模,并根据几何构造,通过位移相容性条件进行耦合。提出了一组局部容许函数,由谐振器域中的全局和局部两部分组成,用于描述振动局部化和位移不连续性。利用所提出的容许函数的 Ritz 方法研究了几何参数和边界条件对板振动特性的影响。全局模态和局部模态之间缺乏正交性是利用所提出方法得到的解析模态函数确定的,并可通过谐振器的自由边界条件加以改变。结果表明,通过对谐振器施加自由边界条件,低阶局部振动频率可显著降低 90%,而对低阶全局频率的影响可以忽略不计。一个新颖而令人兴奋的发现是,全局振动模式可以被频率接近的相应局部振动模式同化。Local–flexural interactive buckling behaviour and design of press-braked stainless steel slender Z-section columnsLi Shuai, Jiang Ke, Zhao Oudoi:10.1016/j.tws.2023.111317压制不锈钢细长 Z 型截面柱的局部挠性 交互屈曲行为和设计The present paper reports an experimental and numerical study on the local–flexural interactive buckling behaviour and resistances of press-braked stainless steel slender Z-section columns. A testing programme adopted two press-braked stainless steel slender Z-sections and included material testing, initial geometric imperfection measurements and twelve fixed-ended column tests, with the experimental setups, procedures and results fully reported. The testing programme was accompanied by a numerical modelling programme, with finite element models developed and validated against the fixed-ended column test results; upon validation, parametric studies were conducted to generate additional numerical data over a wide range of cross-section dimensions and member lengths. The obtained test and numerical data were adopted to evaluate the relevant design rules for press-braked stainless steel slender Z-section columns susceptible to local–flexural interactive buckling, as set out in the American specification and European code. It was revealed from the evaluation results that the American specification led to accurate interactive buckling resistance predictions, while the European code resulted in relatively conservative interactive buckling resistance predictions. Finally, a revised Eurocode design approach was developed and provided more accurate and consistent interactive buckling resistance predictions for press-braked stainless steel slender Z-section columns than its original counterpart.本文报告了对压刹式不锈钢细长 Z 型截面柱的局部-挠性 交互屈曲行为和阻力的实验和数值研究。测试方案采用了两个压制不锈钢细长 Z 型截面,包括材料测试、初始几何缺陷测量和 12 个固定端支柱测试,并全面报告了实验设置、程序和结果。在进行测试计划的同时,还进行了数值建模计划,开发了有限元模型,并根据固定端立柱测试结果进行了验证;在验证后,进行了参数研究,以生成更多横截面尺寸和构件长度范围内的数值数据。根据获得的测试和数值数据,对美国规范和欧洲规范中规定的易受局部挠性 交互屈曲影响的压煞不锈钢细长 Z 型截面柱的相关设计规则进行了评估。评估结果表明,美国规范得出了准确的交互式抗屈曲预测,而欧洲规范得出了相对保守的交互式抗屈曲预测。最后,开发了一种经过修订的欧洲规范设计方法,与原来的设计方法相比,该方法为压制不锈钢细长 Z 型截面柱提供了更准确、更一致的交互式抗屈曲预测。INFLUENCE OF TRANSVERSE STIFFENING ON THE LATERAL-TORSIONAL BUCKLING RESISTANCE OF BUILT-UP I-GIRDERSDeshpande Ajinkya M., Sherman Ryan J., White Donald W.doi:10.1016/j.tws.2023.111320横向加劲对加层工字梁抗横向扭转屈曲性能的影响Recent studies have shown that the AISC 360 Specification substantially overpredicts the strength of certain built-up steel I-girders subjected to high moment gradient. These strength overpredictions have been attributed to various effects, including (1) the direct scaling of the uniform bending lateral-torsional buckling (LTB) strength curve by the elastically-derived moment gradient factor, Cb, without considering the yielding induced at the larger predicted strengths, (2) reduction in the elastic LTB strength due to web shear and corresponding elastic distortional buckling effects, (3) compression flange lateral bending due to amplification of the initial flange sweep, and (4) intensification of the compression flange lateral bending due to web distortion. This paper scrutinizes the impact of transverse stiffening on the elastic and inelastic LTB resistance of a suite of I-girders previously evaluated experimentally and numerically without transverse stiffening through full-nonlinear shell finite element analysis test simulations. The results provide further insight into the sources of the AISC Specification overpredictions and the practical aspects of adding transverse web stiffeners to increase the LTB strength.最近的研究表明,AISC 360 规范大大高估了某些承受高弯矩梯度的加固钢工字梁的强度。这些强度预测过高归因于各种效应,包括:(1)通过弹性推导的弯矩梯度系数 Cb 直接缩放均匀弯曲侧向扭转屈曲(LTB)强度曲线,而未考虑在预测强度较大时引起的屈曲;(2)由于腹板剪切和相应的弹性扭曲屈曲效应导致弹性 LTB 强度降低;(3)由于初始翼缘扫描放大导致压缩翼缘侧向弯曲;以及(4)由于腹板扭曲导致压缩翼缘侧向弯曲加剧。本文通过全非线性壳体有限元分析测试模拟,仔细研究了横向加劲对一系列工字梁弹性和非弹性 LTB 抗力的影响,这些工字梁之前在没有横向加劲的情况下进行了实验和数值评估。研究结果进一步揭示了 AISC 规范预测过高的原因,以及增加横向腹板加劲件以提高 LTB 强度的实用性。Nonlinear vibration and stability of sandwich functionally graded porous plates reinforced with graphene platelets in subsonic flow on elastic foundationWang Zongcheng, Yao Guodoi:10.1016/j.tws.2023.111327用石墨烯微粒增强的夹层功能分级多孔板在弹性地基上的亚音速流动中的非线性振动和稳定性This paper investigates the nonlinear vibration and stability of a functionally graded porous sandwich plate reinforced with graphene platelets (GPLR-SFGP) interacting with subsonic airflow on elastic foundation. The plate comprises of a functionally graded porous core with graphene platelet reinforcement and two metal face layers. Utilizing Hamilton's principle, the nonlinear equation of the plate is exported and discretized into ordinary equations using the assumed modes method. The influence of porosity, GPL weight fraction, surface thickness ratio and Winkler Pasternak elastic foundation arguments on the critical divergence velocity of the plate under subsonic flow is revealed by calculating the system characteristic values. The Matcont toolbox is occupied to generate nonlinear amplitude frequency resonance curves, allowing for a comprehensive examination of the influence of these parameters on the nonlinear resonance behavior of the system. The GPLR-SFGP plate exhibits outstanding characteristics, including superior stiffness and a reduced mass, rendering it a suitable choice for exterior applications in airplanes, automobiles, and high-speed railways. The findings in this study can provide valuable insight into the key design parameters that significantly affect the performance of GPLR-SFGP plates, enabling future design efforts aimed at enhancing their efficacy and robustness in real-world applications.本文研究了在弹性地基上与亚音速气流相互作用的石墨烯微粒增强功能分级多孔夹层板(GPLR-SFGP)的非线性振动和稳定性。该夹层板由一个带石墨烯微粒增强的功能分级多孔板芯和两个金属面层组成。利用汉密尔顿原理,板的非线性方程被导出,并通过假定模态法离散为普通方程。通过计算系统特征值,揭示了孔隙率、GPL 重量分数、表面厚度比和 Winkler Pasternak 弹性基础参数对亚音速流动下板临界发散速度的影响。利用 Matcont 工具箱生成非线性振幅频率共振曲线,可全面检查这些参数对系统非线性共振行为的影响。GPLR-SFGP 板具有优异的特性,包括刚度高、质量小,因此适合用于飞机、汽车和高速铁路的外部应用。本研究的发现为我们深入了解对 GPLR-SFGP 板性能有重大影响的关键设计参数提供了宝贵的资料,使我们能够在未来的设计工作中努力提高其在实际应用中的功效和稳健性。Bending behavior of 3D printed sandwich structures with different core geometries and thermal aging durationsTunay Mervedoi:10.1016/j.tws.2023.111329 具有不同核心几何形状和热老化持续时间的 3D 打印夹层结构的弯曲行为In recent years, the Fused Deposition Modeling (FDM) method has been employed in the production of small-scale structural elements with moderate loads, such as small-unmanned aerial vehicles, sports equipment, dental implant molds, and similar applications. In these cases, the FDM technique can utilize polymers like Polyamide (PA), Polylactic Acid (PLA), and Acrylonitrile Butadiene Styrene (ABS) to manufacture structural components. Lightweight sandwich structures are utilized as structural elements in various industries due to their unique characteristics, high stiffness-to-weight ratio, and energy absorption capabilities. Although the number of studies on the mechanical properties of sandwich structures manufactured with FDM has increased in recent years, experimental data on the mechanical characteristics of sandwich structures manufactured with FDM under different thermal aging durations are still insufficient. Driven by this motivation, the energy absorption capabilities of sandwich structures with different four core geometries (i.e., circular, hexagonal, square, and triangular) were experimentally investigated under different thermal aging durations. The sandwich structures were manufactured from PLA material by the FDM method. Four different thermal aging durations, 0, 15, 30 and 45 days, were considered for environmental conditions. Quasi-static three-point bending experiments were conducted to assess the energy absorption capability of lightweight sandwich structures featuring diverse core topologies. The bending test results demonstrate that the core topology significantly affects the energy absorption abilities of sandwich structures. Moreover, fractographic analysis using scanning electron microscopy (SEM) was conducted to gain deeper insights into the impact of thermal aging on aged specimens. In addition, it was concluded that the energy absorption performances of all sandwich structures with different core structure topologies were adversely affected by increasing the thermal aging time.近年来,熔融沉积建模(FDM)方法已被用于生产负荷适中的小型结构件,如小型无人驾驶飞行器、运动器材、牙科植入物模具等类似应用。在这些情况下,FDM 技术可利用聚酰胺 (PA)、聚乳酸 (PLA) 和丙烯腈-丁二烯-苯乙烯 (ABS) 等聚合物制造结构部件。轻质夹层结构因其独特的特性、高刚度重量比和能量吸收能力而被用作各行各业的结构元件。尽管近年来对使用 FDM 制造的夹层结构的机械性能的研究越来越多,但对使用 FDM 制造的夹层结构在不同热老化持续时间下的机械性能的实验数据仍然不足。在这一动机的驱动下,实验研究了四种不同夹芯几何形状(即圆形、六角形、方形和三角形)的夹层结构在不同热老化持续时间下的能量吸收能力。夹层结构由聚乳酸材料通过 FDM 方法制造而成。环境条件考虑了四种不同的热老化持续时间,分别为 0、15、30 和 45 天。通过准静态三点弯曲实验来评估采用不同芯材拓扑结构的轻质夹层结构的能量吸收能力。弯曲试验结果表明,夹芯拓扑结构对夹层结构的能量吸收能力有很大影响。此外,还利用扫描电子显微镜(SEM)进行了断口分析,以深入了解热老化对老化试样的影响。此外,研究还得出结论:随着热老化时间的延长,具有不同芯材拓扑结构的所有夹层结构的能量吸收性能都会受到不利影响。Hysteretic behavior of replaceable low yield point steel links with corrugated webHe Jun, Feng Sidong, Teng Qiang, Lin Weiwei, Shao Yongbo, Hassanein M.F.doi:10.1016/j.tws.2023.111330带波纹腹板的可更换低屈服点钢连接件的滞后行为To develop a new replaceable steel link with high energy dissipation capacity for establishing a rapid recoverable system of bridge piers, a novel demountable and replaceable low yield point steel links with corrugated web (LCSW link) is proposed. A series quasi-static test on six specimens was conducted to investigate their failure process and hysteretic behaviors, considering the effects of different material and shape of the webs, as well the height-to-span ratio of the replaceable link. The experimental results indicate that the LCSW links exhibit three types of failure modes: the local buckling of steel flanges, the welding fracture at flange-to-endplate connection, and the combination of welding fracture at flange-to-endplate connection and shear buckling of CSWs. The hysteretic behaviors of the specimens were mainly affected by the height-to-span ratio. Moreover, utilization of a small height-to-span ratio (1.7 in this paper) and low yield point steel (LYP160 steel) in the links improves the ductility and energy dissipation capacity. Three-dimensional nonlinear finite element models were established to simulate the hysteretic behavior of the LCSW links, and the yield strength and initial stiffness of the LCSW links under lateral loading were obtained through finite element simulation and simplified design method. The comparison of experimental and analytical results indicates that the finite element models were able to simulate the cyclic response well, and these proposed theoretical equations can be used efficiently to predict the capacity of LCSW links.为了开发一种具有高消能能力的新型可更换钢连接件,以建立桥墩快速恢复系统,我们提出了一种新型可拆卸、可更换的波纹腹板低屈服点钢连接件(LCSW 连接件)。对六个试件进行了一系列准静力试验,以研究其破坏过程和滞后行为,同时考虑了腹板不同材料和形状以及可更换连接件的高跨比的影响。实验结果表明,LCSW 连接件表现出三种失效模式:钢翼缘板的局部屈曲、翼缘板与端板连接处的焊接断裂以及翼缘板与端板连接处的焊接断裂和 CSW 的剪切屈曲。试样的滞后行为主要受高跨比的影响。此外,在连接件中使用较小的高跨比(本文中为 1.7)和低屈服点钢材(LYP160 钢)可提高延展性和耗能能力。本文建立了三维非线性有限元模型来模拟 LCSW 连杆的滞后行为,并通过有限元模拟和简化设计方法获得了 LCSW 连杆在横向荷载作用下的屈服强度和初始刚度。实验结果和分析结果的对比表明,有限元模型能够很好地模拟循环响应,这些提出的理论方程可以有效地用于预测 LCSW 链接的承载能力。Impact dynamics analyses on an innovative fiber reinforced rubber composite bumper system for bridge protectionYan Hongfei, Jia Enshi, Fang Hai, Zhu Lu, Zhang Xinchen, Dai Zhiweidoi:10.1016/j.tws.2023.111331 用于桥梁保护的创新型纤维增强橡胶复合材料保险杠系统的冲击动力学分析To protect the bridge and reduce damage resulted in ship collisions, an innovative fiber reinforced rubber composite bumper system was proposed in this work, which composed of steel box and soft body. By changing the impact speed of cart and the steel box web spacing, 3 specimens were tested. Through the horizontal impact test by using the scaled model, impact force time history curves were obtained. The collision failure modes were analyzed. It could observe that the anti-collision facilities not only have the capacity to reduce damage to ships, but also protect the pier. The energy absorption behavior was analyzed. Moreover, main piers of a cable-stayed bridge with actual size were equipped with fiber reinforced rubber composite bumper systems for further collision simulation. Several ship-bridge collisions with and without anti-collision facilities were simulated. At the speed of 2.26 m/s, the peak forces on ship and pier during the collision with fiber reinforced rubber composite bumper system were 11.28 MN and 13.10 MN respectively, which were 25.94% and 13.99% lower than the peak force 15.23 MN of the collision case without fiber reinforced rubber composite bumper system. The analysis results reveal that the facilities are capable to not only increase the collision duration, but also protect ships and bridge piers. The parameter study on the velocity shows that the fiber reinforced rubber composite bumper system is able to resist the impact of higher energy. Stiffener and soft layer thickness changes can also affect impact force response.为了保护桥梁,减少船舶碰撞造成的损害,本研究提出了一种创新的纤维增强橡胶复合材料保险杠系统,该系统由钢箱和软体组成。通过改变小车的撞击速度和钢箱腹板间距,对 3 个试件进行了测试。通过使用比例模型进行水平冲击试验,获得了冲击力时间历程曲线。分析了碰撞失效模式。结果表明,防撞设施不仅能减少对船舶的损害,还能保护码头。分析了能量吸收行为。此外,还为实际尺寸的斜拉桥主墩配备了纤维增强橡胶复合材料缓冲系统,以进一步模拟碰撞。模拟了有防撞设施和无防撞设施的几次船桥碰撞。在速度为 2.26 m/s 时,装有纤维增强橡胶复合材料防撞系统的船与桥墩碰撞时的峰值力分别为 11.28 MN 和 13.10 MN,比未装有纤维增强橡胶复合材料防撞系统的碰撞时的峰值力 15.23 MN 低 25.94% 和 13.99%。分析结果表明,该设施不仅能延长碰撞持续时间,还能保护船舶和桥墩。对速度参数的研究表明,纤维增强橡胶复合材料缓冲系统能够抵抗更高能量的撞击。刚性层和软层厚度的变化也会影响撞击力响应。来源:复合材料力学仿真Composites FEM

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