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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

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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 Structures

Mechanics of Assembling Two-Dimensional Materials on a Solid Substrate by Droplet Drying

Chen Ziyu, Liu Qingchang, Xu Baoxing

doi: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 Solids

Elastic energy and polarization transport through spatial modulation

Cheng Wen, Zhang Hongkuan, Wei Yu, Wang Kun, Hu Gengkai

doi: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 Materials

Compression of filled, open-cell, 3D-printed Kelvin lattices

Carlsson 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 Structures

A semi-analytical method for vibration localization of plates integrated with low-frequency plate-type resonators

Xue Jian, Zhang Weiwei, Wu Jing, Wang Chao, Ma Hongwei

doi: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 columns

Li Shuai, Jiang Ke, Zhao Ou

doi: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-GIRDERS

Deshpande 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 foundation

Wang Zongcheng, Yao Guo

doi: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 durations

Tunay Merve

doi: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 web

He 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 protection

Yan Hongfei, Jia Enshi, Fang Hai, Zhu Lu, Zhang Xinchen, Dai Zhiwei

doi: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
ACTMechanicalSystemDeform振动断裂复合材料碰撞非线性船舶汽车电子ADS焊接理论材料分子动力学
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【新文速递】2023年11月6日复合材料SCI期刊最新文章

今日更新:Composite Structures 12 篇,Composites Part A: Applied Science and Manufacturing 1 篇Composite StructuresTorsional mechanical properties and damage mechanism of glass fiber-ramie hybrid circular tubeKe Jun, Liu Li-jie, Wu Zhen-yu, Le Zhong-ping, Bao Luo, Luo Dong-weidoi:10.1016/j.compstruct.2023.117680玻璃纤维-拉米混合圆管的扭转力学性能和损伤机理Compared with other green natural fibers, ramie has higher mechanical properties and lower cost. In this study, ramie and glass fiber are made into composite circular tubes by two-dimensional braiding, and their torsional mechanical properties and damage mechanisms are investigated. The results show that under the unit wall thickness, compared with the pure glass fiber circular tube, the maximum torsion angle of the hybrid circular tube with ramie and glass fiber spindle ratio of 1:3 increases by 78%, the weight is reduced by 22%, the cost is reduced by 14%, the maximum torque is increased by 10% and the torsional stiffness is reduced by 18.75%. When the loading direction is the same as the implantation direction with more glass fiber content, the failure is caused by buckling. When the loading direction is the same as the implantation direction with more ramie content, the failure is caused by matrix fracture or fiber fracture. The numerical simulation results of the damage model are consistent with the experimental data and the damage morphology, which verifies the effectiveness of the finite element model. These conclusions provide a reference for the engineering application of composite circular tubes with environmental protection, lightweight and anti-torsion failure ability.与其他绿色天然纤维相比,苎麻具有更高的机械性能和更低的成本。本研究将苎麻和玻璃纤维通过二维编织制成复合圆管,并对其扭转力学性能和损伤机理进行了研究。结果表明,在单位壁厚条件下,与纯玻璃纤维圆管相比,苎麻与玻璃纤维主轴比为 1:3 的混合圆管的最大扭转角增加了 78%,重量减轻了 22%,成本降低了 14%,最大扭矩增加了 10%,扭转刚度降低了 18.75%。当加载方向与玻璃纤维含量较多的植入方向相同时,破坏是由屈曲引起的。当加载方向与植入方向相同且苎麻含量较多时,破坏是由基体断裂或纤维断裂引起的。损伤模型的数值模拟结果与实验数据和损伤形态一致,验证了有限元模型的有效性。这些结论为具有环保、轻质和抗扭转破坏能力的复合材料圆管的工程应用提供了参考。Free vibration characteristics of integrated fluted-core composite sandwich cylindersLi Xinyu, Zhang Hao, Yang Haiyang, Luo Junrong, Xiao Zhongmin, Lei Hongshuaidoi:10.1016/j.compstruct.2023.117691 集成凹槽夹芯复合材料圆柱体的自由振动特性Due to their excellent mechanical properties and inherent design versatility, fluted-core composite sandwich structures have gained substantial attention in aerospace and rail transit applications. This study investigated the free-vibration characteristics of composite fluted-core sandwich cylinders. Theoretical models were established following the Rayleigh-Ritz method to predict the natural frequencies of sandwich cylinders under free vibration. The representative cylindrical specimens were prepared using carbon fiber-reinforced plastics (CFRP) and integrated forming co-cured method. To analyze the additional effects of cutouts on vibration performance, specimens with circular cutouts were also fabricated. The vibration tests were performed to determine the natural frequencies and modal shapes under free-free boundary conditions. Validated finite element simulations were employed to assess the accuracy of theoretical results and investigate the influences of geometric parameters on the structural vibration behavior. The results indicated that circumferential lobar modes characterized the first five mode shapes. Significant enhancements were attained by increasing the structural stiffness through adjustments in the circumferential cell number, core-ribs thickness, or size of cutouts. However, when the structural stiffness increases beyond a certain threshold, it has limited effect on the vibration frequencies. The findings provided a comprehensive understanding of the vibration characteristics and optimized design of fluted-core sandwich cylinders.由于具有优异的机械性能和固有的设计多功能性,凹槽芯复合材料夹层结构在航空航天和轨道交通应用中得到了广泛关注。本研究调查了复合材料凹槽夹芯圆柱体的自由振动特性。采用雷利-里兹法建立了理论模型,以预测夹层圆柱体在自由振动下的固有频率。使用碳纤维增强塑料(CFRP)和集成成型共固化方法制备了具有代表性的圆柱形试样。为了分析切口对振动性能的额外影响,还制作了带有圆形切口的试样。振动测试用于确定自由边界条件下的固有频率和模态振型。为了评估理论结果的准确性,并研究几何参数对结构振动行为的影响,采用了经过验证的有限元模拟。结果表明,圆周叶状模态是前五种模态振型的特征。通过调整圆周单元数、芯肋厚度或切口尺寸来增加结构刚度,可以显著提高振动性能。然而,当结构刚度增加超过一定临界值时,对振动频率的影响有限。研究结果为凹槽夹芯圆柱体的振动特性和优化设计提供了全面的理解。Optimal thickness distribution design for blending composite laminates using buckling factor predictionHuynh Thanh N., Lee Jaehongdoi:10.1016/j.compstruct.2023.117693利用屈曲因子预测混合复合材料层压板的最佳厚度分布设计This article introduces a two-stage optimization approach for finding optimal blended composite laminate designs where the optimal thickness distribution is predicted based on determined stacking sequences. At each iteration, the stacking sequences are first optimized and then utilized as inputs to predict the optimal regional thicknesses through CNN-based regional buckling factor prediction. By predicting the optimal thicknesses, the proposed process simplifies the highly constrained mixed-variable blending optimization problem, expands its option space, and reduces the number of design variables, all of which improve the combinatorial optimization efficiency. An integration of the proposed approach with a design guideline-based Genetic Algorithm is presented. The approach is applied to solve an 18-panel benchmark blending problem, the acquired solutions are compared with those of previous studies in the literature. The obtained result highlights the significant enhancement in performance of the integrated method.本文介绍了一种用于寻找最佳混合复合材料层压板设计的两阶段优化方法,根据确定的堆叠顺序预测最佳厚度分布。在每次迭代中,首先优化堆叠序列,然后将其作为输入,通过基于 CNN 的区域屈曲因子预测来预测最佳区域厚度。通过预测最佳厚度,所提出的流程简化了高度受限的混合变量混合优化问题,扩大了其选项空间,并减少了设计变量的数量,所有这些都提高了组合优化效率。本文介绍了建议方法与基于设计准则的遗传算法的整合。该方法被应用于解决一个 18 面板基准混合问题,所获得的解决方案与之前文献中的研究进行了比较。结果表明,集成方法的性能显著提高。Strength and manufacturability enhancement of a composite automotive component via an integrated finite element / artificial neural network multi-objective optimization approachHenrique Fonseca João, Jang Woojung, Han Dosuck, Kim Naksoo, Lee Hyungyildoi:10.1016/j.compstruct.2023.117694通过综合有限元/人工神经网络多目标优化方法提高汽车复合材料部件的强度和可制造性This study addresses the enhancement of an injection-molded fiber-reinforced plastic / metal hybrid automotive structure and its plastic injection molding process through the integration of the finite element method, artificial intelligence and evolutionary search methods. Experiments are conducted to validate the finite element models. The orthogonal array and Latin hypercube methods are employed to generate a database via finite element analysis. The database is then used to train artificial neural networks that accurately evaluate component distortion, manufacturing time, and structural strength. A genetic optimization algorithm is applied to identify optimal process parameters. The procedure was demonstrated to simultaneously reduce product warpage and manufacturing time by 10 and 62 %, respectively, when compared with the reference manufacturing process while strength is kept above the required levels with a reduced number of required data points. A more in-depth investigation into the causes of strength variation and deformation is also provided. The results contribute to the advance of robust composite automotive structures with superior quality, manufactured through efficient processes.本研究通过整合有限元方法、人工智能和进化搜索方法,对注塑成型的纤维增强塑料/金属混合汽车结构及其注塑成型工艺进行改进。实验验证了有限元模型。采用正交阵列法和拉丁超立方法通过有限元分析生成数据库。然后利用该数据库训练人工神经网络,以准确评估部件变形、制造时间和结构强度。遗传优化算法用于确定最佳工艺参数。结果表明,与参考制造流程相比,该流程可同时将产品翘曲和制造时间分别减少 10% 和 62%,同时在减少所需数据点数量的情况下将强度保持在所需水平之上。此外,还对强度变化和变形的原因进行了更深入的研究。这些结果有助于推动通过高效工艺制造出质量上乘的坚固复合材料汽车结构。Formation of non-uniform fibre distribution and its effect on the flexural performance of pultruded GFRP box beamsQi Songming, Alajarmeh Omar, Alhawamdeh Mohammad, Shelley Tristan, Schubel Peter, Rendle-Short Kendric, Zeng Xuesendoi:10.1016/j.compstruct.2023.117695 非均匀纤维分布的形成及其对拉挤 GFRP 箱形梁弯曲性能的影响This study investigates the effect of non-uniform fibre distribution (NUFD) as a defect in the pull-winding manufacturing process on the mechanical properties of pultruded glass fibre-reinforced polymer (GFRP) box section profiles. These profiles exhibit balanced mechanical properties but are susceptible to NUFD during production, negatively affecting local buckling capacity. Experimental and numerical analyses were conducted on pultruded GFRP profiles manufactured under three winding tension configurations, resulting in a 5% variance in load capacity during bending. Results show that corner NUFD influences local buckling capacity more than flange NUFD. Specifically, corner NUFD decreases load capacity by up to 20%, while flange NUFD increases it by up to 3%. Conversely, the effect of NUFD location is insignificant to the failure determined by the material strength without buckling instability. Moreover, a linear relationship between the rotational restraint coefficient and corner fibre volume fraction provides insight into the impact of material imperfections on load capacity.本研究调查了非均匀纤维分布(NUFD)这一拉卷制造过程中的缺陷对拉挤玻璃纤维增强聚合物(GFRP)箱型材机械性能的影响。这些型材具有均衡的机械性能,但在生产过程中容易出现 NUFD,对局部屈曲能力产生负面影响。我们对在三种缠绕张力配置下生产的拉挤 GFRP 型材进行了实验和数值分析,结果显示弯曲时的负载能力差异为 5%。结果表明,转角 NUFD 比凸缘 NUFD 对局部屈曲能力的影响更大。具体来说,角部无损探伤最多会降低 20% 的承载能力,而凸缘无损探伤最多会提高 3%。相反,NUFD 位置的影响对于由材料强度决定的无屈曲不稳定性的失效并不明显。此外,旋转约束系数与边角纤维体积分数之间的线性关系有助于深入了解材料缺陷对承载能力的影响。Manufacturing and characterization of an interpenetrating metal matrix composite reinforced with a 3D-printed metallic glass lattice structure (Ni60Nb20Ta20)Dittmann Kerstin, Trauth Anna, André Weidenmann Kaydoi:10.1016/j.compstruct.2023.117697用 3D 打印金属玻璃晶格结构(Ni60Nb20Ta20)增强的互穿金属基复合材料的制造与表征Metallic glasses (MG) exhibit remarkable properties, like high strength, hardness, and elastic strain limit due their amorphous structure. But they also exhibit low ductility and brittle behavior, making them less suitable for monolithic components. Therefore, MG offer high potential for use as a reinforcing phase in a ductile matrix. Especially interpenetrating metal matrix composites (MMCs) are suitable, since good interfacial adhesion can be achieved due to the metallic character of the MG and mechanical properties can be further enhanced by the interpenetrating structure. Temperature during manufacturing process must be below crystallization temperature of the MG. Until now, interpenetrating MMCs have been manufactured by infiltrating the metal matrix foam with MG, requiring a high melting temperature of the matrix and thus excludes lightweight metals. In this work it was possible to infiltrate an open porous lattice structure of MG (Ni60Nb20Ta20) due to its high crystallization temperature with AlSi12 by gas pressure infiltration resulting in a novel MMC. X-ray diffraction measurements confirm that no crystallization occurred during infiltration. Micrographs show a good infiltration quality and interfacial bonding between both phases. An increase in Young's modulus of 28% and compressive strength in the MMC can be achieved compared to the AlSi12-matrix.金属玻璃(MG)因其无定形结构而具有高强度、硬度和弹性应变极限等显著特性。但它们也表现出低延展性和脆性,因此不太适合用于整体元件。因此,MG 作为韧性基体中的增强相具有很大的应用潜力。特别是互穿金属基复合材料(MMC),因为 MG 的金属特性可以实现良好的界面粘附性,互穿结构可以进一步提高机械性能。制造过程中的温度必须低于 MG 的结晶温度。迄今为止,互穿式 MMC 都是通过在金属基泡沫塑料中渗入 MG 来制造的,这要求基体具有较高的熔化温度,因此不包括轻质金属。在这项工作中,由于 MG(Ni60Nb20Ta20)的结晶温度较高,因此可以通过气压渗透将其与 AlSi12 一起渗透到开放多孔晶格结构中,从而制造出新型 MMC。X 射线衍射测量证实,在浸润过程中没有发生结晶。显微照片显示,两相之间的浸润质量和界面结合良好。与 AlSi12 基质相比,MMC 的杨氏模量和抗压强度提高了 28%。Concurrent stacking sequence and layout optimization of stiffened composite plates using a spectral element method and an index-based optimization techniqueAlan Salih, Shaban Nefize, Sendur Gullu Kiziltas, Bediz Bekirdoi:10.1016/j.compstruct.2023.117698使用谱元法和基于指数的优化技术同时优化加劲复合板的堆叠顺序和布局Stiffened composite panels are increasingly used in aerospace, marine, and automotive industries due to their lightweight and high-strength properties. However, determining the optimal stacking sequence and/or layout of stiffeners concurrently while adhering to manufacturing guidelines and empirical rules is challenging. To address this issue, we propose a novel one-step optimization framework that couples a highly accurate and computationally efficient spectral element modeling technique with an index-based optimization approach that inherently satisfies the manufacturing guideline and empirical rules. Spectral element modeling (SEM) combines the high accuracy of spectral (meshless) methods with the geometric flexibility of finite element methods. To determine the optimal design, an index-based optimization is proposed to decrease the number of design variables and remove the constraints. We demonstrated the accuracy and computational performance of SEM with results obtained by finite element analysis on composite laminates with and without a cutout. Finally, we applied the proposed optimization framework to various stiffened composite (balanced and symmetric) laminates of up to 200 plies to demonstrate its capability and efficiency.由于具有轻质高强的特性,加劲复合板越来越多地应用于航空航天、船舶和汽车行业。然而,在遵守制造准则和经验规则的同时,确定加劲件的最佳堆叠顺序和/或布局极具挑战性。为解决这一问题,我们提出了一种新颖的一步优化框架,该框架将高精度、高计算效率的谱元建模技术与基于索引的优化方法结合起来,从本质上满足了制造准则和经验规则。谱元建模(SEM)结合了谱(无网格)方法的高精度和有限元方法的几何灵活性。为了确定最佳设计,我们提出了一种基于指数的优化方法,以减少设计变量的数量并消除约束。我们通过对有切口和无切口的复合材料层压板进行有限元分析所获得的结果,证明了 SEM 的准确性和计算性能。最后,我们将提出的优化框架应用于多达 200 层的各种加劲复合材料(平衡和对称)层压板,以证明其能力和效率。Post-Buckling Behavior and Collapse of Double-Double Composite Single Stringer SpecimensVescovini A., Li C.X., Paz J., Jin B., Manes A., Bisagni C.doi:10.1016/j.compstruct.2023.117699双层复合单弦杆试件的屈曲后行为和坍塌This paper presents the work on six single-stringer specimens manufactured using the card-sliding technique with non-crimp fabrics and adopting a Double-Double (DD) stacking sequence. These specimens, representative of sub-structure level components, are used to investigate post-buckling and failure in aerospace structures. Two specimens maintain a constant thickness cross-section, while four are tapered, two of which incorporate a Teflon insert in the stringer flange. All specimens are tested under compression loading conditions, inducing skin buckling, skin-stringer separation, and eventual collapse. Numerical simulations are validated by experimental results and serve to analyze the specimens behavior and the failure mode. The load versus displacement curves of both experimental tests and Finite Element Method (FEM) analyses are compared, along with the out-of-plane displacement field. Subsequently, the observed failure modes are discussed, focusing on the various mechanisms that occurred and considering the impact of flanges and stiffener tapering. Both the FEM simulations and experimental tests demonstrate good agreement, with the flanges tapering revealing notable results. This offers promising evidence of a viable solution to optimize aeronautical structures and enhance resistance to skin-stringer separation.本文介绍了采用无皱织物的卡片滑动技术和双倍(DD)堆叠顺序制造的六个单弦试样。这些试样代表子结构级部件,用于研究航空航天结构的后屈曲和失效。两个试样保持恒定厚度的横截面,四个试样为锥形,其中两个试样在支撑翼缘中加入了特氟龙插入物。所有试样均在压缩加载条件下进行测试,以诱发蒙皮屈曲、蒙皮-弦杆分离和最终坍塌。实验结果对数值模拟进行了验证,并对试样的行为和破坏模式进行了分析。比较了实验测试和有限元法(FEM)分析的载荷与位移曲线以及平面外位移场。随后,对观察到的失效模式进行了讨论,重点是发生失效的各种机理,并考虑了法兰和加劲件锥度的影响。有限元模拟和实验测试均显示出良好的一致性,其中法兰锥度的结果尤为显著。这为优化航空结构和提高抗蒙皮弦杆分离能力提供了可行的解决方案。A Dovetail Core Design for Joints in Composite Sandwich StructuresAqel Rawan, Severson Patrick, Elhajjar Ranidoi:10.1016/j.compstruct.2023.117700复合材料夹层结构接缝的燕尾芯设计The increase in the size of composite sandwich structures requires the introduction of core splices to join various segments. In this study, a novel core splice joint configuration is studied and proposed for composite sandwich structures of thick aluminum-based honeycomb core and facesheets made from carbon fibers and epoxy matrix. Experimental and numerical efforts investigate the impact of dovetail joints with different tenon angles on the auxiliary behavior of composite sandwich structures. The results are compared to conventional or straight-core splices without dovetail features. The core-splice interaction with the complete mechanical behavior of the system was assessed by subjecting the fabricated specimens to combinations of bending and shear forces. Additionally, 3D-finite element models compared normal and shear stresses in the splice material and the core/splice interface among the dovetail configurations considered. The study shows that depending on the dovetail joint detail, an ultimate strength increase between 13 to 51% is achieved compared to the strength from currently used straight joints. In terms of toughness, the dovetail specimens show a 2% to 35% higher toughness compared to the standard straight joints.随着复合材料夹层结构尺寸的增大,需要采用芯材拼接来连接各个部分。本研究针对由厚铝基蜂窝芯材和由碳纤维及环氧基质制成的面材组成的复合材料夹层结构,研究并提出了一种新型芯材拼接接头结构。实验和数值研究了不同榫角的燕尾接头对复合材料夹层结构辅助行为的影响。实验结果与传统或无燕尾槽的直芯拼接进行了比较。通过对制作的试样施加弯曲力和剪切力组合,评估了芯材拼接与系统整体机械行为的相互作用。此外,三维有限元模型还比较了所考虑的燕尾槽配置中拼接材料和芯材/拼接界面的法向应力和剪切应力。研究结果表明,根据燕尾接头细节的不同,与目前使用的直接头相比,其极限强度可提高 13% 至 51%。在韧性方面,与标准直接头相比,燕尾槽试样的韧性提高了 2% 至 35%。Form-finding of elastic gridshell based on spatial elastica modelWANG Xianheng, CHEN Cong, ZHANG Jinsong, QIU Xinmingdoi:10.1016/j.compstruct.2023.117653基于空间弹性模型的弹性网格壳的形状确定In engineering design, elastic gridshells, which are composed of a number of elastic rods, are advantageous because they are lightweight, easy to construct, and low-cost as well as have a long-span space. However, the form-finding of a gridshell is challenging owing to the large deformation and strong geometric-nonlinearity of the structure. In this paper, a new form-finding method based on spatial elastica model (FMSE) is proposed. The deformations of elastic rods, obtained via the elliptic integral solution of spatial elastica, is integrated into the overall deformation of the gridshell. A set of transcendental equations is solved using the quasi-Newton method to ensure that the deformation of the gridshell satisfies the given boundary conditions. To validate the proposed FMSE method, desktop experiments (designed using the theory of Chebyshev nets) are performed on gridshells made of glass fiber reinforced polymer rods. The predictions of the FMSE method agree well with the experimental results. Accordingly, the proposed FMSE method is expected to have potential applications in elastic gridshells, on the investigations of form-finding, load-bearing capability, non-local deformation behavior, and also stability of structures.在工程设计中,由许多弹性杆组成的弹性栅壳具有重量轻、易于建造、成本低以及跨度空间大等优点。然而,由于网格壳结构的大变形和强几何非线性,网格壳的形状搜索具有挑战性。本文提出了一种基于空间弹性模型(FMSE)的全新找形方法。通过空间弹性椭圆积分求解得到的弹性杆的变形被整合到网格壳的整体变形中。使用准牛顿法求解一组超越方程,以确保网格壳的变形满足给定的边界条件。为了验证所提出的 FMSE 方法,在玻璃纤维增强聚合物棒制成的网格壳上进行了桌面实验(利用切比雪夫网理论设计)。FMSE 方法的预测结果与实验结果非常吻合。因此,所提出的 FMSE 方法有望应用于弹性网格壳,研究结构的寻形、承载能力、非局部变形行为以及稳定性。Design and optimization of the dual-functional lattice-origami metamaterialsJiang Tengjiao, Han Sihao, Han Qiang, Li Chunleidoi:10.1016/j.compstruct.2023.117670双功能晶格原形超材料的设计与优化This study proposes a multi-scale composite lattice-origami metamaterial (MCLOM) to achieve excellent bandgap characteristics and energy absorption capacities. The MCLOMs are constructed by considering the high impedance mismatch of lattice structures, the spatial deformability of origami structures, and the tunability of the components in multi-scale composite materials. Firstly, elastic wave propagation characteristics are analyzed in the Bloch wave framework, revealing the realization of complete bandgaps and their generation mechanism by mode shape analysis and transmission spectrum. Subsequently, an optimization framework integrating the particle swarm optimization (PSO) algorithm is developed to maximize the first bandgap’s bandwidth by adjusting various component parameters. Under optimal distribution, the proposed metamaterials achieve remarkable improvements of 289% and 271% in the design objectives of two lattice-origami metamaterials with 90° dihedral angle compared to the initial distribution. It can be demonstrated that non-uniform distributions of multi-scale composite materials are dramatically effective for broadband wave attenuation. Additionally, while striving to widen the bandgap, the energy absorption capacities of structures are also crucial. The effect of the distribution of multi-scale composite materials with the optimal bandgap on the energy absorption performance is investigated. The results reveal that the optimal distribution of the lattice-origami metamaterials yields notable improvements of 48.26% and 34.86% under low-velocity impact, and 37.41% and 25.19% under medium-velocity impact. This work presents innovative concepts and approaches for devising and implementing novel dual-functional metamaterials, undoubtedly propelling the continual progress of material science and engineering technology in the times ahead.本研究提出了一种多尺度复合晶格-折纸超材料(MCLOM),以实现优异的带隙特性和能量吸收能力。考虑到晶格结构的高阻抗失配性、折纸结构的空间变形性以及多尺度复合材料中各成分的可调谐性,构建了 MCLOM。首先,在布洛赫波框架下分析了弹性波的传播特性,通过模形分析和透射谱揭示了完整带隙的实现及其产生机制。随后,结合粒子群优化(PSO)算法建立了一个优化框架,通过调整各种组件参数来最大化第一带隙的带宽。在最佳分布条件下,与初始分布相比,所提出的超材料在两个具有 90° 二面角的晶格原形超材料的设计目标上分别实现了 289% 和 271% 的显著改进。这表明,多尺度复合材料的非均匀分布对宽带波衰减具有显著效果。此外,在努力拓宽带隙的同时,结构的能量吸收能力也至关重要。本文研究了具有最佳带隙的多尺度复合材料的分布对能量吸收性能的影响。结果表明,晶格原形超材料的最佳分布在低速撞击下分别产生了 48.26% 和 34.86% 的显著改善,在中速撞击下分别产生了 37.41% 和 25.19% 的显著改善。这项研究提出了设计和实现新型双功能超材料的创新理念和方法,无疑将推动材料科学和工程技术在未来时代的不断进步。Multi-phase metamaterials containing framework structures to program thermal expansion and mechanical performancesWang Kaiyu, Chen Jiaxin, Wei Kai, Wang Rong, Yang Xujingdoi:10.1016/j.compstruct.2023.117671包含框架结构的多相超材料可实现热膨胀和机械性能编程Due to suffering the thermal and mechanical loadings simultaneously, metamaterials integrating with the customizable coefficient of thermal expansion (CTE) and high mechanical performances are desirable to ensure the thermal and structural stabilities in engineering devices. Hence, various multi-phase metamaterials with programmable CTEs and mechanical performances were developed. Specifically, inspired by the mixture of multiple phases in composites and the rigid rotations of framework structures in materials with negative CTE, a typical pyramid unit was introduced. Additionally, two series of metamaterials were systematically designed, which were constructed in batches from different units through the matrix transformation method. The CTEs of the metamaterials were theoretically established and analyzed. Besides, mechanical performances, including relative density, stiffness and strength were also calculated and discussed. The results suggest that the directionality and magnitude of CTEs are determined by the constructing principle of multi-fold rotations. In addition, the large ranges of programmable CTEs and high load-bearing capacity are available in the devised metamaterials by reasonably modulating the geometrical parameters. The thermal expansion and mechanical performances of the metamaterials could be synchronously programmed. The diversity of the phase configurations and geometrical architectures in the metamaterials offers the opportunity to satisfy manifold requirements in different applications.由于要同时承受热负荷和机械负荷,具有可定制热膨胀系数(CTE)和高机械性能的超材料是确保工程设备热稳定性和结构稳定性的理想选择。因此,各种具有可编程热膨胀系数和机械性能的多相超材料应运而生。具体来说,受复合材料中多相混合以及负 CTE 材料中框架结构刚性旋转的启发,引入了典型的金字塔单元。此外,还系统地设计了两个系列的超材料,通过矩阵变换方法由不同单元分批构建而成。理论上确定并分析了超材料的 CTE。此外,还计算并讨论了超材料的力学性能,包括相对密度、刚度和强度。结果表明,CTE 的方向性和大小由多倍旋转的构造原理决定。此外,通过合理调节几何参数,设计出的超材料还具有大范围的可编程 CTE 和高承载能力。超材料的热膨胀和机械性能可同步编程。超材料相位配置和几何结构的多样性为满足不同应用的多方面要求提供了机会。Composites Part A: Applied Science and ManufacturingObservations of Wrinkling in Non-Crimp Fabrics during Multi-Ply Stack Forming using In situ XCT ScanningJimenez-Martin Claudia, Maes Vincent, Rosini Sebastian, Smith Ronan, Sinclair Ian, Mavrogordato Mark, McMahon Turlough, Kratz Jamesdoi:10.1016/j.compositesa.2023.107880使用原位 XCT 扫描观察多层堆叠成形过程中非起皱织物的起皱情况This paper shows the internal evolution of wrinkles occurring in a single diaphragm forming process using time-resolved in situ XCT scanning. Forming trials were carried out over a curved C-spar geometry using Non-Crimp Fabric (NCF) plies of 45°/135°, 0°/90° and 0°/45° orientations arranged in single-orientation and mixed-orientation stacks. Results show most of the diaphragm movement and change in wrinkle size, shape, and location occurs in the early application (<0.1 bar) of vacuum. The further application of vacuum shows consolidation, with wrinkle size decreasing but shape and location remaining largely unchanged. Single-orientation stacks of 45°/135° plies showed the closest resemblance between initial and final wrinkling, while mixed-orientation stacks showed complex wrinkling due to the 0° plies creating internal ply separation due to excess length. Overall, the study shines a light on the internal interaction between layers that occurs during wrinkling, showing mechanisms only observable with XCT.本文利用时间分辨原位 XCT 扫描技术展示了单隔膜成形过程中皱纹的内部演变过程。成型试验是在弯曲的 C 型支柱几何形状上进行的,使用的是以单一方向和混合方向堆叠排列的 45°/135°、0°/90° 和 0°/45° 方向的无皱褶织物 (NCF) 层。结果表明,隔膜的大部分移动以及皱纹大小、形状和位置的变化都发生在施加真空的初期(小于 0.1 巴)。进一步施加真空后会出现巩固,皱纹的大小会减小,但形状和位置基本保持不变。由 45°/135° 层组成的单取向叠层显示出初始和最终皱纹之间最接近的相似性,而混合取向叠层则显示出复杂的皱纹,这是因为 0° 层由于长度过长而产生了内部层间分离。总之,这项研究揭示了起皱过程中发生的层间内部相互作用,显示了只有 XCT 才能观察到的机制。来源:复合材料力学仿真Composites FEM

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