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【新文速递】2023年11月20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 2 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 2 篇

International Journal of Solids and Structures

Frequency domain Green’s function and boundary integral equations for multifield materials and quasicrystals

Pasternak Viktoriya, Sulym Heorhiy, Pasternak Iaroslav M.

doi:10.1016/j.ijsolstr.2023.112562

多场材料和准晶体的频域格林函数和边界积分方程

Present paper considers anisotropic elastic, magnetoelectroelastic and quasicrystal solids. It is shown that the equations of time-harmonic motion and constitutive relations for considered materials can be presented in the compact and unified form. The matrix approach is proposed for derivation of 3D time-harmonic Green’s functions for considered materials. The cases of each material type are studied separately. Two models of phason field dynamics in quasicrystals are considered in details. It is shown that in the case of phason field models based on the use of hydrodynamic formulations, phonon oscillations have an elastic nature, while the phason field leads to their decay due to phonon-phason interaction. The strict proof is given to the statement that the eigenvalues of the time-harmonic magnetoelectroelaticity problem are all positive. The paper also shows the application of the obtained time-harmonic Green’s functions in obtaining the boundary integral equations for the considered classes of problems. For this purpose, the novel approach is proposed, which utilizes only the symmetry of the unified material property tensor and the inertia matrix. Derived boundary integral equations can be used in the solution of boundary value problems for considered classes of materials.

本文研究了各向异性弹性、磁电弹性和准晶体固体。研究表明,所考虑材料的时谐运动方程和构成关系可以以紧凑统一的形式呈现。为推导所考虑材料的三维时谐格林函数,提出了矩阵方法。对每种材料的情况分别进行了研究。详细考虑了准晶体中的两种相声场动力学模型。结果表明,在基于流体力学公式的声子场模型中,声子振荡具有弹性性质,而声子场则由于声子-声子相互作用而导致其衰减。本文对时谐磁电静问题的特征值均为正值这一说法给出了严格的证明。论文还展示了所获得的时谐格林函数在获得所考虑问题类别的边界积分方程中的应用。为此,论文提出了一种新方法,即只利用统一材料属性张量和惯性矩阵的对称性。推导出的边界积分方程可用于求解所考虑材料类别的边界值问题。


Journal of the Mechanics and Physics of Solids

Pinning cracks by microstructure design in brittle materials

Xiong Xun, Zeng Qinglei, Wang Yonghuan, Li Ying

doi:10.1016/j.jmps.2023.105497

脆性材料微观结构设计中的针状裂纹

In this work, we explore the possibility of controlling toughening mechanisms in brittle materials through microstructure design to enhance their resistance to crack growth. First, a computational framework is established using the distinct element method (DEM) with J integral implemented to simulate complex crack propagation and characterize the effective fracture energy of brittle materials. The fracture behavior of a soda-lime glass plate containing pre-existing voids under tensile loading is simulated, and toughening mechanisms associated with the existence of voids, including blunting-induced pinning and deflection-induced pinning, are identified in brittle materials. Then we seek to modulate the fracture toughness of brittle materials by introducing either randomly distributed voids or sinusoidally distributed voids and controlling the pinning events. Our findings reveal that randomly distributed voids with different volume fractions induce only modest toughening in brittle materials. Sinusoidally distributed voids with specific amplitude and wavelength trigger both crack blunting and deflection in the vicinity of voids, increasing the probability of crack pinning and leading to a significant increase in crack growth resistance. Moreover, we identify the critical conditions for the "embrittlement-toughening transition" and "maximized toughening". Finally, we discuss the difference between void toughening for brittle materials and ductile materials due to distinct toughening mechanisms activated, and also extend the toughening strategy to nacre-like materials. The stairwise herringbone structure is demonstrated to be a promising candidate for structure optimization due to unique stiffness, strength, and toughness.

在这项研究中,我们探讨了通过微结构设计控制脆性材料增韧机制的可能性,以增强其抗裂纹生长的能力。首先,我们利用独特的元素法(DEM)建立了一个计算框架,并将该框架与 J 积分来模拟复杂的裂纹扩展,并描述脆性材料的有效断裂能。我们模拟了含有预先存在空隙的钠钙玻璃板在拉伸载荷下的断裂行为,并确定了脆性材料中与空隙存在相关的增韧机制,包括钝化诱导针 刺和挠曲诱导针 刺。然后,我们试图通过引入随机分布的空隙或正弦曲线分布的空隙并控制针 刺事件来调节脆性材料的断裂韧性。我们的研究结果表明,不同体积分数的随机分布空隙只能对脆性材料产生适度的增韧作用。具有特定振幅和波长的正弦分布空隙会在空隙附近引发裂纹钝化和挠曲,增加裂纹针销的概率,从而显著提高裂纹生长阻力。此外,我们还确定了 "脆化-韧化转变 "和 "最大化韧化 "的临界条件。最后,我们讨论了脆性材料和韧性材料由于激活了不同的增韧机制而产生的空隙增韧差异,并将增韧策略扩展到了珍珠质材料。由于具有独特的刚度、强度和韧性,阶梯状人字形结构被证明是结构优化的理想候选材料。


Angle-dependent protrusion of cell membranes

Tang Huayuan, Ye Hongfei, Zhang Hongwu, Yi Xin, Zheng Yonggang

doi:10.1016/j.jmps.2023.105500

细胞膜的角度突起

Protrusion induced by cylindrical tubes against cell membranes plays essential roles in numerous biological processes, including filopodia growth, cellular packing or entry of one-dimensional nanomaterials, and indentation of cells by needle-like probes. Though the mechanical interaction between the cell membrane and a perpendicular tube has been widely investigated, little is known about how an inclined protruding tube interacts with the cell membrane. Here, we theoretically investigate the angle-dependent protrusion of cylindrical tubes against cell membranes. It is found that perpendicular protrusion is stabilized by the elastic deformation of cell membranes. Increasing the angle between the protrusion direction and perpendicular direction or increasing membrane tension leads to an increasing peak force for the membrane tubulation and increasing plateau resistive force for the maintenance of membrane tubules. Moreover, two fundamental protruding modes leading to the tip-roof and finial-roof system configurations are identified. Inclined protrusion retards the configurational transition from the tip-roof to the finial-roof configuration, and causes possible bending and buckling of protruding tubes due to a large membrane resistive force. Our results offer fundamental insights into the interaction between cell membranes and one-dimensional nanomaterials, and contribute to the understanding and control of membrane protrusion in biological systems.

圆柱管对细胞膜的突起在许多生物过程中发挥着重要作用,包括丝状体的生长、细胞的包装或一维纳米材料的进入,以及针状探针对细胞的压入。虽然细胞膜与垂直管之间的机械相互作用已被广泛研究,但人们对倾斜的突出管如何与细胞膜相互作用却知之甚少。在此,我们从理论上研究了圆柱形管与细胞膜之间随角度变化的突起。研究发现,细胞膜的弹性变形稳定了垂直突起。增大突出方向与垂直方向之间的角度或增加膜张力会导致膜管化的峰值力增加,而维持膜管化的高原阻力增加。此外,还确定了两种基本的突出模式,分别导致尖端-屋顶和顶端-屋顶系统配置。倾斜突起延缓了从顶端-屋顶构型到顶盖-屋顶构型的构型转变,并由于较大的膜阻力可能导致突起管弯曲和屈曲。我们的研究结果从根本上揭示了细胞膜与一维纳米材料之间的相互作用,有助于理解和控制生物系统中的膜突起。


International Journal of Plasticity

Ductile ultrastrong China low activation martensitic steel with lamellar grain structure

Zhou J.H., Wang J., Ritchie Robert O., Wu Y.C., Cheng J.W., Wang L., Yin X.W., Jiang Y.F., Ren J.G.

doi:10.1016/j.ijplas.2023.103813

具有片状晶粒结构的韧性超强中国低活化马氏体钢

The low high-temperature mechanical properties of reduced activated ferrite martensitic (RAFM) heat-resistant steels limit the maximum operating temperature of nuclear fusion reactors. However, it is difficult to improve the strength of the material without reducing its plasticity. In this study we prepared a China low activation martensitic (CLAM) steel with a layered structure through hot rolling followed by low-temperature tempering, which successfully improved its strength and ductility. In addition, we elucidate the ductility mechanisms in such lamellar structural materials. When the strength of the grain boundaries exceeds that of the grains, cracks will continuously extend along the layered grain boundaries, eventually resulting in a delamination fracture mechanism. When the grains strength exceeds that of the grain boundaries, cracks will continuously form through the relative sliding of the grain boundaries, and a large number of small cracks will initiate and propagate longitudinally along the layered boundaries. Both forms of crack propagation cause longitudinal expansion along the layered grain boundaries. The resulting longitudinal extension of cracks markedly diminishes local stress concentration to promote plastic deformation, thereby significantly increasing the ductility of the material. Employing the combination of this delamination ductility mechanism with interface strengthening and precipitation strengthening, the strength of the CLAM steel for nuclear applications is shown to be enhanced by ∼30% without loss of elongation. The current delamination ductility strategy provides a unique pathway to develop materials with ultrahigh strength and superior ductility at economical material costs.

还原活化铁素体马氏体(RAFM)耐热钢的高温机械性能较低,限制了核聚变反应堆的最高工作温度。然而,要在不降低材料塑性的情况下提高其强度却很困难。在这项研究中,我们通过热轧和低温回火制备了具有层状结构的中国低活化马氏体(CLAM)钢,成功提高了其强度和延展性。此外,我们还阐明了这种层状结构材料的延性机理。当晶界强度超过晶粒强度时,裂纹会沿着层状晶界不断延伸,最终形成分层断裂机制。当晶粒强度超过晶界强度时,裂纹会通过晶界的相对滑动不断形成,大量细小裂纹会沿着层状晶界纵向扩展。这两种形式的裂纹扩展都会导致沿层状晶界的纵向扩展。由此产生的裂纹纵向扩展明显减少了局部应力集中,促进了塑性变形,从而显著提高了材料的延展性。将这种分层延展机制与界面强化和析出强化相结合,用于核应用的 CLAM 钢的强度可提高 30%,而伸长率不会降低。当前的分层延展性策略为以经济的材料成本开发具有超高强度和卓越延展性的材料提供了一条独特的途径。


Thin-Walled Structures

Coupled vibration analysis of a rotating pre-twist blade-hub assembly with a setting angle reinforced by graphene nanoplatelets

Yan Kai, Zhao Tian Yu, Ma Hui

doi:10.1016/j.tws.2023.111287

用石墨烯纳米片强化带设定角的旋转预扭叶片-轮毂组件的耦合振动分析

Due to its light weight and great mechanical performance, the spinning blade-hub assembly are widely used in modern rotary machines, such as the aero-engine, gas turbine, and so on. This paper conducted theoretical modeling and vibration analysis of a functionally graded (FG) pre-twist blade-hub rotor structure with a setting angle reinforced by graphene nanoplatelets (GPLs), where the hub and blade are modeled by elastic cylindrical shell and plate, respectively. To improve the structural stiffness, the blade-hub (plate-cylindrical shell) assembly is prepared from graphene nanoplatelet (GPL) reinforcement and polymer matrix. Both uniform and nonuniform GPL distributions are considered in the plate and cylindrical shell, which leads to a FG assembly. Determined via the Halpin-Tsai model and the rule of the mixture, the effective material properties vary continuously along the thickness direction of the plate and cylindrical shell. According to the Kirchhoff plate theory and the Donnell shell theory, the coupled equations of motion of the FG rotating blade-hub assembly are derived by using the Lagrange's equation. Moreover, the component mode synthesis (CMS) and assumed mode method are applied to obtain the free vibration results of the blade-hub rotor. By employing the finite element method, the theoretical model and analysis is verified. Finally, special attention is given to the influence of the material parameters (GPL distribution pattern, GPL weight fraction, GPL length-to-thickness ratio and GPL length-to-width ratio) and structural parameters (blade pre-twist angle and blade setting angle) on the free vibration frequency of the composite blade-hub rotor system.

由于重量轻、机械性能好,旋转叶片-轮毂组件被广泛应用于航空发动机、燃气轮机等现代旋转机械中。本文对石墨烯纳米片(GPL)增强的带设定角的功能分级(FG)预扭转叶片-轮毂转子结构进行了理论建模和振动分析,其中轮毂和叶片分别以弹性圆柱壳和板为模型。为了提高结构刚度,叶片-轮毂(板-圆柱壳)组件由石墨烯纳米片(GPL)增强材料和聚合物基质制备而成。在板和圆柱形外壳中考虑了均匀和不均匀的 GPL 分布,从而得到了 FG 组件。通过 Halpin-Tsai 模型和混合物规则确定,有效材料特性沿板和圆柱形外壳的厚度方向连续变化。根据基尔霍夫板理论和唐奈壳理论,利用拉格朗日方程推导出 FG 旋转叶片-轮毂组件的耦合运动方程。此外,还应用了组件模态综合法(CMS)和假定模态法来获得叶片-轮毂转子的自由振动结果。通过采用有限元方法,对理论模型和分析进行了验证。最后,特别关注了材料参数(GPL 分布模式、GPL 重量分数、GPL 长厚比和 GPL 长宽比)和结构参数(叶片预扭角和叶片设置角)对复合材料叶片-轮毂转子系统自由振动频率的影响。


Free vibration of thin, creased elastic plates: Optimization and scaling laws

Vijayachandran Avinkrishnan A., Oudghiri-Idrissi Othman, Danawe Hrishikesh, Mao Xiaoming, Arruda Ellen, Tol Serife, Waas Anthony M.

doi:10.1016/j.tws.2023.111393

皱褶弹性薄板的自由振动:优化和缩放定律

Creasing, crumpling, and folding help to increase the flexural rigidity of thin elastic plates. In this study, the fundamental frequency is used as a measure of improvement in flexural stiffness. Firstly, an analysis of an orderly, creased, thin elastic plate with nine separate pyramidal crumples is presented. Such a plate shows an increase of 124% in the fundamental frequency with only a 0.5% increase in the total mass/ surface area when compared to that of a flat configuration. Further, scaling laws are introduced for such ordered creased structures for three separate cases- scaling based on (i) the total surface area of the structure, (ii) the amplitude/ height of the ordered pyramidal crumples, and (iii) the number of unit cells within a given edge length of the plate. Further, an optimization problem is posed to achieve maximum flexural stiffness under given constraints for an additively manufactured thin, elastic plate supported on all four edges. The objective is posed as a constrained optimization problem maximizing the fundamental frequency of the structure compared to that of a flat sheet. The results are promising, with a 176% increase in stiffness with only a 0.84% increase in the total mass/ surface area.

压痕、皱褶和折叠有助于提高弹性薄板的抗弯刚度。在本研究中,基频被用来衡量抗弯刚度的改善程度。首先,我们分析了一个有序折皱、带有九个独立金字塔形皱褶的弹性薄板。与平面结构相比,这种板的基频提高了 124%,而总质量/表面积仅增加了 0.5%。此外,还针对三种不同的情况为这种有序皱褶结构引入了缩放定律--缩放基于 (i) 结构的总表面积,(ii) 有序金字塔皱褶的振幅/高度,以及 (iii) 板给定边长内的单元格数量。此外,还提出了一个优化问题,即在给定约束条件下,使加成法制造的四边都有支撑的弹性薄板达到最大挠曲刚度。与平板相比,该问题的目标是使结构的基频最大化。结果很有希望,在总质量/表面积仅增加 0.84% 的情况下,刚度增加了 176%。




来源:复合材料力学仿真Composites FEM
ACTMechanicalAdditiveSystemMAGNET振动断裂复合材料旋转机械航空裂纹理论材料控制
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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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