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【新文速递】2024年5月21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,International Journal of Plasticity 2 篇,Thin-Walled Structures 1 篇

International Journal of Solids and Structures

Contact formulations for analysis of micropolar media with finite continuum beam elements

L. Obrezkov, B. Bozorgmehri, R. Kouhia, M.K. Matikainen

doi:10.1016/j.ijsolstr.2024.112880

用有限连续光束单元分析微极介质的接触公式

Microscale beam-like structures are standard components of micromechanical systems in many devices. However, the small dimensionality affects their deformation characteristics and leads to misinterpretations of the results. Presenting such size dependency is possible with advanced continuum descriptions via introducing additional variables compared to the classical one. Hence, the problems where contact occurs require the readjustment of boundary conditions considering these extra parameters. That burdens the already challenging task of contact problem calculations and restricts most demonstration examples to two-dimensional problems and geometrical linearity. The resolution of the imposed restrictions within finite element modeling further emphasizes the usage of advanced media in design and facilitates its application to various problems, which is the aim of this paper. The delivery of that task is as follows. Firstly, we present the kinematics and material descriptions for the micropolar media. The authors propose to use a newly developed continuum-based micropolar beam formulation to avoid an overwhelming computational burden and, at the same time, deal with nonlinear stress–strain relations. Secondly, the work develops a contact approach within the micropolar theory from two-dimensional to three-dimensional elasticity, although the contact is considered frictionless. Finally, it compares two existing contact formulations, including the developed one, for the contact beam problems, using the examples of two collinear sliding beams’ bending.

在许多设备中,微尺度梁状结构是微机械系统的标准部件。然而,小维度影响了它们的变形特性,导致了对结果的误读。与经典的连续体相比,通过引入额外的变量,先进的连续体描述可以呈现这种大小依赖关系。因此,发生接触的问题需要考虑这些额外的参数重新调整边界条件。这增加了接触问题计算的难度,并限制了大多数的演示例子只能解决二维问题和几何线性问题。解决有限元建模中所施加的限制,进一步强调了先进介质在设计中的使用,并促进了其在各种问题中的应用,这是本文的目的。该任务的交付如下。首先,我们给出了微极介质的运动学和材料描述。作者建议使用新开发的基于连续体的微极梁公式,以避免压倒性的计算负担,同时处理非线性应力-应变关系。其次,该工作在微极理论中发展了从二维到三维弹性的接触方法,尽管这种接触被认为是无摩擦的。最后,以两根共线滑动梁的弯曲为例,比较了现有的两种接触公式,包括所开发的接触公式。


Journal of the Mechanics and Physics of Solids

An interpenetrating-network theory of the cytoskeletal networks in living cells

Haiqian Yang, Thomas Henzel, Eric M. Stewart, Ming Guo

doi:10.1016/j.jmps.2024.105688

活细胞中细胞骨架网络的互穿网络理论

Cells undergo dramatic deformations during many physiological and pathological processes such as division and migration, and their mechanical integrity is supported by cytoskeletal networks (i.e. intermediate filaments, F-actin, and microtubules). Recent observations of cytoplasmic microstructure indicate interpenetration among different cytoskeletal networks, and micromechanical experiments have shown evidence of complex characteristics in the mechanical response of the interpenetrating cytoskeletal networks of living cells, including viscoelastic, nonlinear stiffening, microdamage, and healing characteristics (Hu et al., 2019). However, a theoretical framework describing such a response is missing, and thus it is not clear how different cytoskeletal components with distinct mechanical properties come together to build the overall complex mechanical features of the cytoskeletal networks. In this work, we address this gap by developing a finite-deformation continuum-mechanical theory with a multi-branch visco-hyperelastic constitutive relation coupled with phase-field damage and healing. The proposed interpenetrating-network model elucidates the coupling among interpenetrating cytoskeletal components, and the roles of finite elasticity, viscoelastic relaxation, damage, and healing in the experimentally-observed mechanical response of interpenetrating cytoskeletal networks in living eukaryotic cells.

细胞在分裂和迁移等生理和病理过程中会发生剧烈变形,其机械完整性由细胞骨架网络(即中间丝、f -肌动蛋白和微管)支持。最近对细胞质微观结构的观察表明,不同的细胞骨架网络之间存在相互渗透,微力学实验表明,活细胞相互渗透的细胞骨架网络的机械响应具有复杂的特征,包括粘弹性、非线性硬化、微损伤和愈合特征(Hu等人,2019)。然而,缺乏描述这种反应的理论框架,因此尚不清楚具有不同机械性能的不同细胞骨架成分如何聚集在一起以构建细胞骨架网络的整体复杂机械特征。在这项工作中,我们通过发展具有多分支粘-超弹性本构关系的有限变形连续力学理论,结合相场损伤和愈合来解决这一差距。提出的互穿网络模型阐明了互穿细胞骨架组分之间的耦合,以及实验观察到的真核细胞互穿细胞骨架网络力学响应中有限弹性、粘弹性松弛、损伤和愈合的作用。


International Journal of Plasticity

Constitutive modelling of glassy polymers considering shear plasticity and craze yielding

Zhouzhou Pan, Huanming Chen, Laurence Brassart

doi:10.1016/j.ijplas.2024.103996

考虑剪切塑性和开裂屈服的玻璃聚合物本构模型

The inelastic behaviour of thermoplastic polymers below the glass transition temperature can involve shear plasticity or crazing, depending on the strain rate and temperature. Shear plasticity is driven by local shear stresses and is essentially volume preserving. In contrast, crazing is a failure phenomenon occurring under tension and causes significant volume change. In some cases, crazing can also result in large inelastic deformations at macroscopic scale, referred to as craze yielding. The aim of this study is to propose a thermodynamically-consistent constitutive framework that accounts for both shear plasticity and craze yielding in glassy polymers. The main assumption is that shear plasticity and craze yielding occur exclusively from each other, depending on the local stress state. Both are modelled as thermally-activated processes with different activation stresses and flow rules. The theory is validated against experimental data for polylactic acid (PLA). Our model is capable of reproducing the stress–strain response including yielding, softening, and drawing under both shear plasticity and craze yielding, and also accurately predicts the volumetric deformation under tension. In particular, our simulations well capture the interesting phenomenon that craze yielding stabilises localised deformations and prevents necking. Our model can also simulate complex scenarios where both mechanisms occur simultaneously at different locations of the specimen.

热塑性聚合物在玻璃化转变温度以下的非弹性行为可能涉及剪切塑性或裂纹,这取决于应变速率和温度。剪切塑性是由局部剪应力驱动的,本质上是保持体积的。相比之下,起皱是一种在张力作用下发生的破坏现象,会导致显著的体积变化。在某些情况下,开裂也会导致宏观尺度上的大的非弹性变形,称为开裂屈服。本研究的目的是提出一个热力学一致的本构框架,该框架考虑了玻璃聚合物的剪切塑性和开裂屈服。主要假设是剪切塑性和开裂屈服只发生在彼此之间,取决于局部应力状态。两者都被建模为具有不同激活应力和流动规则的热激活过程。用聚乳酸(PLA)的实验数据对理论进行了验证。该模型能够再现剪切塑性和开裂屈服下的屈服、软化和拉伸等应力应变响应,并能准确预测拉伸作用下的体积变形。特别是,我们的模拟很好地捕获了一个有趣的现象,即裂纹屈服稳定了局部变形并防止了颈缩。我们的模型还可以模拟两种机制同时发生在试件不同位置的复杂情况。


Unraveling the Hall-Petch to Inverse Hall-Petch Transition in Nanocrystalline High Entropy Alloys under Shock Loading

Wanghui Li, Meizhen Xiang, Zachary Howard Aitken, Shuai Chen, Yilun Xu, Xinyu Yang, Qingxiang Pei, Jian Wang, Xiaoyan Li, Guglielmo Vastola, Huajian Gao, Yong-Wei Zhang

doi:10.1016/j.ijplas.2024.104010

冲击载荷下纳米晶高熵合金中Hall-Petch向逆Hall-Petch转变的研究

The transition from Hall-Petch (HP) to inverse Hall-Petch (IHP) behaviors associated with grain size reduction has been recognized for over two decades. However, the underlying mechanisms for such transition in high entropy alloys (HEAs) under dynamic loading, in which abundant deformation mechanisms could be activated either sequentially or simultaneously, remain unclear. Here, we investigate the HP to IHP transition in nanocrystalline CoCrFeMnNi HEAs under shock loading by examining their deformation mechanisms and flow stresses using large-scale molecular dynamics (MD) simulations. It is found that this transition is strongly dependent on the shock pressure as a result of the complex interplay among multiple competing deformation mechanisms, including the hardening mechanisms such as dislocations interactions and grain boundary (GB) blocking, as well as the softening mechanisms like phase formation, amorphization, GB thickening, and grain rotation. Moreover, there exists a critical shock pressure, which corresponds to the largest critical grain size for the HP-IHP transition. Below the critical shock pressure, the critical grain size increases with pressure due to a stronger hardening effect in grain interior (GIs), while above the critical pressure, the critical grain size first decreases and then undergoes a pressure-insensitive plateau before further decrease due to softening effects in GIs. A theoretical model that includes different deformation mechanisms is proposed for the first time to capture the shock pressure-dependent HP-IHP transition. Our work provides valuable guidance for optimizing the grain size of nanocrystalline HEAs for applications involving dynamic loadings.

从霍尔-佩奇(HP)到与晶粒尺寸减小相关的逆霍尔-佩奇(IHP)行为的转变已经被认识了二十多年。然而,在动态载荷下,高熵合金(HEAs)的这种转变的潜在机制尚不清楚,其中大量的变形机制可以顺序或同时激活。本文采用大尺度分子动力学(MD)模拟方法,研究了CoCrFeMnNi纳米晶HEAs在冲击载荷下从HP到IHP的转变过程。研究发现,这种转变强烈依赖于冲击压力,这是多种竞争变形机制复杂相互作用的结果,包括位错相互作用和晶界阻塞等硬化机制,以及相形成、非晶化、晶界增厚和晶粒旋转等软化机制。此外,存在一个临界冲击压力,该压力对应于HP-IHP相变的最大临界晶粒尺寸。当冲击压力低于临界冲击压力时,由于晶粒内部的硬化作用更强,临界晶粒尺寸随压力增大而增大;而当冲击压力高于临界冲击压力时,由于晶粒内部的软化作用,临界晶粒尺寸先减小,然后进入一个压力不敏感的平台期,再进一步减小。一个理论模型,包括不同的变形机制,首次提出捕捉冲击压力相关的HP-IHP转换。我们的工作为动态加载应用中纳米晶HEAs的晶粒尺寸优化提供了有价值的指导。


Thin-Walled Structures

Local damage and imperfection sensitivities of pyramidal core sandwich cylinders

Shuai Kang, Wu Yuan, Hongwei Song

doi:10.1016/j.tws.2024.112020

锥心夹层柱的局部损伤及缺陷灵敏度

Local damage and imperfections may affect the loading capacity of truss core sandwich cylinders. This study develops a numerical model to investigate the effects of missing lattice struts, unbound nodes, openings, and eigenmode-shape imperfections on the buckling and post-buckling behavior of pyramidal core sandwich cylinders. Results from the numerical model show that the pyramidal core sandwich cylinder is sensitive to missing struts and unbound nodes when local buckling is the main failure model. Critical loads show a gradual decrease as the opening damage increases. Pyramidal core sandwich cylinders are not sensitive to eigenmode-shape imperfections compared to the equivalent single-walled shells.

局部损伤和缺陷会影响桁架芯筒的承载能力。本研究建立了一个数值模型来研究缺失的晶格支柱、未绑定节点、开口和特征模态缺陷对锥形芯芯夹层柱屈曲和后屈曲行为的影响。数值模拟结果表明,当局部屈曲为主要破坏模式时,锥体芯芯夹层柱对缺失支撑和未绑定节点敏感;随着开口损伤的增加,临界载荷逐渐减小。与等效的单壁筒壳相比,锥形芯芯夹芯筒对本征模态缺陷不敏感。



来源:复合材料力学仿真Composites FEM
ACTMechanicalSystemDeform非线性ADSECAD裂纹理论化机材料分子动力学
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首次发布时间:2024-11-14
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【新文速递】2024年5月11日固体力学SCI期刊最新文章

今日更新:International Journal of Solids and Structures 4 篇,Journal of the Mechanics and Physics of Solids 1 篇,Mechanics of Materials 1 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 2 篇International Journal of Solids and StructuresDesign and validation of a new ring hoop plane strain test for characterizing the anisotropic plastic behavior of tubular materialsZied Ktari, Ali Khalfallahdoi:10.1016/j.ijsolstr.2024.112869用于表征管状材料各向异性塑性行为的新型环箍平面应变试验的设计与验证The accurate characterization of the plastic behavior of tubular materials is challenging due to the difficulties in acquiring proper specimens for mechanical testing. In this study, we propose a novel testing technique, namely the ring hoop plane strain Test (RHPST), as a supplementary test for characterizing materials experiencing distinct strain paths compared to standard uniaxial tensile tests. To design a suitable ring specimen’s geometry that satisfies the necessary plane strain conditions, we developed a meta-modelling approach merging response surface method (RSM) and the finite element method (FEM). Experimental tests are conducted on RHPST specimens, and 3D digital image correlation (DIC) technique is used to monitor the strain fields within the specimen's gauge section. However, observations indicate the presence of edge effects on the gauge specimen. These edge effects significantly influence and limit the homogeneity of the plane strain field. To tackle this limitation, a correction procedure is developed for separating the authentic plane strain area, constituting approximately 78% of the RHPST specimen's width. Furthermore, we successfully fabricated a novel grooved ring specimen (GRHPST), which exhibits a wider region of the plane strain state encompassing up to 90% of the gauge width, while minimizing the impact of edge effects. The true stress-true strain curve obtained from the GRHPST specimen exhibits exceptional agreement with the curve predicted using the Hill48 yield criterion. Notably, no additional corrections are required for the measured true stress-true strain curve, thereby affirming the efficacy of the GRHPST specimen as an adept test for characterizing the anisotropic plastic behavior of AA6063 tubes.由于难以获得适当的力学测试样品,因此准确表征管状材料的塑性行为具有挑战性。在这项研究中,我们提出了一种新的测试技术,即环箍平面应变试验(RHPST),作为一种补充测试,用于表征与标准单轴拉伸试验相比经历不同应变路径的材料。为了设计满足平面应变条件的环形试件几何形状,提出了一种融合响应面法(RSM)和有限元法(FEM)的元建模方法。对RHPST试件进行了实验测试,并采用三维数字图像相关(DIC)技术对试件计截面内的应变场进行了监测。然而,观察表明存在边缘效应的规范试样。这些边缘效应显著地影响和限制了平面应变场的均匀性。为了解决这一限制,开发了一种校正程序,用于分离真实的平面应变区域,该区域约占RHPST试件宽度的78%。此外,我们成功地制作了一种新型的沟槽环试件(GRHPST),它显示出更宽的平面应变状态区域,包括高达90%的规宽,同时最小化了边缘效应的影响。从GRHPST试样获得的真应力-真应变曲线与使用Hill48屈服准则预测的曲线异常一致。值得注意的是,测量的真应力-真应变曲线不需要额外的修正,从而肯定了GRHPST试样作为表征AA6063管各向异性塑性行为的有效试验。Non-Oscillatory fracture mode partition for interface crack under Mixed-Mode loadingChang-Wei Liu, Tz-Cheng Chiudoi:10.1016/j.ijsolstr.2024.112871混合模态加载下界面裂纹的非振荡断裂模式划分The oscillatory crack-tip field in the classical interface fracture mechanics solution often leads to complications in identifying the mode mixity in bimaterial interface fracture problems. In this paper, a non-singular series solution for the continuum problem of a crack on the cohesive-spring interface under mixed-mode loading is presented and compared to the classical oscillatory solution. A Gaussian process regression model was also developed to enable quick evaluation of the phase angle for interface delamination characterization by using mixed-mode bending fracture test.经典界面断裂力学解法中裂纹尖端的振荡场往往导致双材料界面断裂问题中模态混合识别的复杂性。本文给出了黏结-弹簧界面裂纹在混合模态载荷作用下的连续问题的非奇异级数解,并与经典振动解进行了比较。建立了高斯过程回归模型,通过混合模弯曲断裂试验快速评估界面分层表征的相位角。Investigation of fracture patterns and effect on capacity in all-solid-state batteries based on peridynamic electro-chemo-mechanical modelXiaofei Wang, Qi Tongdoi:10.1016/j.ijsolstr.2024.112873基于全固态电池全动态电化学-力学模型的断裂模式及其对容量的影响研究The evolution of complex fracture patterns of composite electrodes in all-solid-state batteries (ASSBs) during electrochemical cycles is one of the main phenomena driving capacity degradation. Such fracture patterns in active materials usually involve cracks with various orientations. While conventional wisdom usually treats fracture as ultimate failure of materials in many scenarios, the effect of crack in batteries is worth further investigation. Here, a concurrently coupled electro-chemo-mechanical model based on peridynamics has been developed to study fracture patterns and electrochemical performances of composite anodes during processes of charge and discharge. The framework consists of a classic bond-based peridynamic mechanical model, an electrochemical model, and a coupling technique to reflect the interaction between them in a bidirectional manner. The bond-based peridynamic mechanical model considers the active material’s elastic–plastic deformation and the solid electrolyte’s elastic deformation. The fracture energies of the active material, the solid electrolyte, and the interface are also incorporated into this model. The electrochemical model considers the volume expansion of the active material caused by the intercalation of lithium ions and the Butler-Volmer relation of charge transfer on the interface. Various parametric analyses are performed using this modeling framework to investigate the effects of external pressure, fracture energies of active material and solid electrolyte, and Young’s modulus on fracture patterns and electrochemical performances. It is found that different material parameters result in distinct fracture patterns in the active material with radial cracks or circumferential cracks, thus profoundly affecting the rates of charge and discharge. This work demonstrates the importance of considering the complex fracture patterns in electrode materials of batteries and provides insights for selecting more suitable electrode materials to mitigate capacity degradation.全固态电池复合电极在电化学循环过程中复杂断裂模式的演变是导致电池容量退化的主要现象之一。活性物质中的这种断裂模式通常包括不同方向的裂缝。传统观点认为,在许多情况下,断裂是材料的最终失效,但裂纹对电池的影响值得进一步研究。本文建立了一种基于周动力学的电化学-力学耦合模型,用于研究复合阳极在充放电过程中的断裂模式和电化学性能。该框架由经典的基于键的周动力学模型、电化学模型和反映它们之间双向相互作用的耦合技术组成。基于键的周动力力学模型考虑了活性材料的弹塑性变形和固体电解质的弹性变形。活性物质、固体电解质和界面的断裂能也被纳入该模型。电化学模型考虑了锂离子的插入引起活性物质的体积膨胀和界面上电荷转移的Butler-Volmer关系。利用该模型框架进行了各种参数分析,以研究外部压力、活性材料和固体电解质的断裂能以及杨氏模量对断裂模式和电化学性能的影响。研究发现,不同的材料参数会导致活性材料出现不同的断裂模式,包括径向裂纹和周向裂纹,从而深刻影响充放电速率。这项工作证明了在电池电极材料中考虑复杂断裂模式的重要性,并为选择更合适的电极材料以减轻容量下降提供了见解。Large deformation of cable networks with fiber sliding as a second-order cone programmingMykola Tkachuk, Anton Tkachukdoi:10.1016/j.ijsolstr.2024.112848带光纤滑动的大变形电缆网络的二阶锥规划A new model for irreversible large deformations of fiber networks is developed. The fibers are considered as inextensible cables that slide relative to each other in the frictional junctions. This sliding is constituted by a rate-independent flow rule. The nonsmooth dissipation potential for each sliding system is defined as a product of the yield strength and the absolute value of the fiber sliding. The response of the cable segments is nonsmooth as well, since it shows asymmetry with respect to tension and compression. A principle of minimum incremental potential and a pure complementary energy principle are derived for the equilibrium incremental loading of the network at large deformations. They form a pair of primal and dual second-order cone programming problems with matching sets of displacement-based and force-based variables. These problems can be effectively solved by interior point methods that have many advantages compared to the gradient-based methods or dynamic relaxation. The model is extended by a simple mechanism of fiber pull-out resulting from fiber sliding at the free unconstrained ends. This can be used for the microstructural analysis of failure of needle-punched nonwoven materials.提出了一种新的光纤网络不可逆大变形模型。纤维被认为是不可扩展的电缆,在摩擦结中相互滑动。这种滑动是由一个速率无关的流动规则构成的。每个滑动系统的非光滑耗散势被定义为屈服强度与纤维滑动绝对值的乘积。索段的响应也是非光滑的,因为它表现出相对于张力和压缩的不对称性。导出了网络在大变形时的平衡增量加载的最小增量势能原理和纯互补能量原理。它们形成了一对具有基于位移和基于力变量的匹配集的原始和对偶二阶锥规划问题。与基于梯度法或动态松弛法相比,内点法具有许多优点,可以有效地解决这些问题。将该模型扩展为纤维在自由无约束末端滑动引起的纤维拉出的简单机制。该方法可用于针 刺非织造材料失效的微观结构分析。Journal of the Mechanics and Physics of SolidsA thermodynamic theory coupling photo-chemo-mechano interactions for light-responsive hydrogelZhe Chen, Xuehan Yang, Xuhan Liu, Chuang Li, Shaoxing Qu, Wei Yangdoi:10.1016/j.jmps.2024.105677光响应水凝胶的光化学-力学相互作用的热力学理论Light-responsive hydrogel, as a typical functional hydrogel, is composed of crosslinked hydrophilic polymer chains, photosensitive molecules and water. Under illumination, the photosensitive molecules exhibit a transition in hydrophilic/ hydrophobic properties, leading to migration of water molecules and deformation of the hydrogel based on the temporal and spatial distribution of light. In this study, we propose a nonequilibrium thermodynamic framework to study the photo-chemo-mechano behaviors of light-responsive hydrogel. We firstly describe the light propagation in the hydrogel and the photochemical reaction kinetics. New free energy functions to expound the relationship between the photochemical reaction and thermodynamic process are established, and the constitutive equations are derived. Subsequently, we implant the model into a multi-field coupling analysis software, COMSOL, to conduct a spatio-temporal analysis of the hydrogel's response under uniform light exposure. Finally, we simulate the inhomogeneous deformation of light-responsive hydrogel strips under different illumination conditions and compare the results with experiments. The results highlight the importance of the photochemical reaction rate and the redistribution of light field caused by deformation. The present research holds potential for the precise manipulation and optimal design of light-responsive hydrogel in prospective applications, and offers insights for the synthesis of similar materials as well as the design of pertinent devices.光响应水凝胶是一种典型的功能水凝胶,由交联的亲水聚合物链、光敏分子和水组成。在光照下,光敏分子表现出亲疏水性质的转变,导致水分子的迁移和基于光的时空分布的水凝胶变形。在这项研究中,我们提出了一个非平衡热力学框架来研究光响应水凝胶的光化学-力学行为。首先描述了光在水凝胶中的传播和光化学反应动力学。建立了新的自由能函数,阐述了光化学反应与热力学过程的关系,并推导了本构方程。随后,我们将该模型植入多场耦合分析软件COMSOL中,对均匀光照下水凝胶的响应进行时空分析。最后,我们模拟了不同光照条件下光响应水凝胶条的不均匀变形,并与实验结果进行了比较。结果强调了光化学反应速率和光场再分布的重要性。本研究为光响应水凝胶的精确操作和优化设计提供了潜在的应用前景,并为类似材料的合成以及相关器件的设计提供了见解。Mechanics of MaterialsBand gap study of periodic piezoelectric micro-composite laminated plates by finite element method and its application in feedback controlH.A. Ma, H.J. Liu, Y. Cong, S.T. Gudoi:10.1016/j.mechmat.2024.105029周期压电微复合材料层合板带隙的有限元研究及其在反馈控制中的应用Phononic crystals are materials or structures with periodic variations of elastic constants and density. Elastic waves in phononic crystals cannot propagate within a certain frequency range, called the band gap, due to the interference of their internal structure. This article investigates how fiber orientation affects the band gap properties of periodic micro-composite laminated plates. We examined the impact of five common composite laminate configurations on the system’s band gap and discovered that the antisymmetric configuration had superior high-frequency band gap performance. Based on this finding, we further explored how the antisymmetric angle influenced the system’s band gap. Since the study was conducted at a micro scale, micro structural effects were considered. Therefore, we used the modified coupled stress elastic dynamics and a four-node quadrilateral non-conforming element to discretize the micro composite laminated plate model, which had the nodal compatibility of high-order elasticity theory. Moreover, we employed feedback control to the proposed structure to dynamically adjust the band gap width according to different practical needs. This research supports the design of periodic micro-composite laminated plates and the piezoelectric feedback control system, which can control the vibration and wave propagation behaviors of micro structures using coupled piezoelectric sensors and actuators. The piezoelectric feedback control employed two control methods: direct proportional control and acceleration control. This article compared the single and multiple control methods of these two approaches to determine the optimal control strategy.声子晶体是弹性常数和密度具有周期性变化的材料或结构。声子晶体中的弹性波由于其内部结构的干扰,不能在一定的频率范围内传播,称为带隙。本文研究了纤维取向对周期性微复合材料层合板带隙性能的影响。我们研究了五种常见的复合材料层压结构对系统带隙的影响,发现反对称结构具有更好的高频带隙性能。在此基础上,我们进一步探讨了反对称角对系统带隙的影响。由于研究是在微观尺度上进行的,因此考虑了微观结构效应。因此,采用修正的耦合应力弹性动力学和四节点四边形非协调单元对具有高阶弹性理论节点相容性的微复合材料层合板模型进行离散化。此外,我们对所提出的结构采用反馈控制,根据不同的实际需要动态调整带隙宽度。该研究支持了周期性微复合材料层合板和压电反馈控制系统的设计,该系统可以通过耦合压电传感器和执行器来控制微结构的振动和波传播行为。压电反馈控制采用直接比例控制和加速度控制两种控制方式。本文对这两种方法的单控制方法和多控制方法进行了比较,以确定最优控制策略。International Journal of PlasticityPhysical mechanism of the intermittent plastic flow at extremely low temperaturesKinga Nalepka, Błażej Skoczeń, Rafał Schmidt, Weronika Zwolińska-Faryj, Elwira Schmidt, Robert Chulistdoi:10.1016/j.ijplas.2024.103994 极低温下塑性间歇流动的物理机理The physical mechanism of the intermittent plastic flow (IPF) of austenitic steels at extremely low temperatures is explained in the context of microstructure evolution and 3D deformation arising in the area of the shear band. The microstructure change is identified by X-ray diffraction with the use of synchrotron radiation as well as electron backscatter diffraction (EBSD). This complete, global and local, approach reveals the intensive formation of twin boundaries which perform two functions. They become a part of the macroscopic shear band, but also constitute barriers piling up dislocations. Thus, their overcoming results in a stress drop as in the case of breaking the Lomer-Cottrell locks. The investigations show that the rapid displacement is blocked by the intensively produced martensite α’. The main features of the uncovered microstructural evolution are captured in the 3D reconstruction of the shear band obtained with the use of profilometer. Moreover, the effect of the thermodynamic instability is taken into account when assessing the conditions of the IPF. Finally, new kinetics of the IPF is developed. It comprises two functions: B reflecting the surface density of the dislocation pile-ups on the internal lattice barriers, and G corresponding to the surface density of twin boundaries. The breakthrough of the work consists in the discovery of multi-scale mechanism of the IPF, including participation of twin boundaries and the Lomer-Cottrell barriers.从剪切带区域的微观结构演变和三维变形的角度解释了奥氏体钢在极低温度下发生间歇塑性流动(IPF)的物理机制。通过同步辐射 X 射线衍射以及电子反向散射衍射 (EBSD) 来确定微观结构的变化。这种全面、整体和局部的方法揭示了孪生边界的密集形成,孪生边界具有两种功能。它们既是宏观剪切带的一部分,也是堆积位错的屏障。因此,克服孪生边界会导致应力下降,就像打破 Lomer-Cottrell 锁一样。研究表明,快速位移被密集产生的马氏体α'阻挡。利用轮廓仪获得的剪切带三维重建捕捉到了未覆盖微观结构演变的主要特征。此外,在评估 IPF 的条件时还考虑了热力学不稳定性的影响。最后,还开发了新的 IPF 动力学。它包括两个函数: B 反映了内部晶格壁垒上位错堆积的表面密度,而 G 则与孪晶边界的表面密度相对应。这项工作的突破在于发现了 IPF 的多尺度机制,包括孪晶边界和 Lomer-Cottrell 势垒的参与。Thin-Walled StructuresNumerical study on the seismic performance of phosphogypsum-filled cold-formed thin-walled steel composite wallsSong Hu, Zongping Chen, Xiaojun Ke, Li Zhoudoi:10.1016/j.tws.2024.111982磷石膏填充冷弯薄壁钢复合墙体抗震性能的数值研究To conduct in-depth research on the seismic performance of phosphogypsum (PG) filled cold-formed thin-walled square steel tube (PFCFS) composite walls, a series of finite element analyses was conducted using the software ABAQUS. The study examined various factors, including PG strength, oriented strand board (OSB) configuration and thickness, stud strength and thickness, screw spacing, axial force ratio, wall sheathing coverage, and height-width ratio. After summarizing, the main findings are as follows: the lateral behavior of walls is significantly affected by PG strength and wall stud thickness, while wall sheathing configuration has a relatively low impact; increasing PG strength, wall stud thickness and strength, wall sheathing thickness, axial force ratio, and the number of wall sheathings (non vs. single vs. double sheathing), or decreasing self-tapping screw spacing and wall height-width ratio enhance the shear capacity of the wall; increasing PG strength, wall sheathing thickness, or reducing wall height-width ratio improve the lateral stiffness and ductility of the wall; increasing wall stud thickness and adding more wall sheathing can improve the lateral stiffness of the wall. However, this can reduce the wall's ductility; by decreasing self-tapping screw spacing or increasing axial force ratio, the lateral stiffness and ductility of the wall exhibit an increasing-then-decreasing trend; increasing wall stud strength does not significantly affect the lateral stiffness of the wall, but it does decrease the ductility. Finally, the simulated lateral stiffness and shear capacity of the wall were compared with the theoretical values, which showed good agreement.为了深入研究磷石膏(PG)填充冷弯薄壁方钢管(PFCFS)复合墙体的抗震性能,采用ABAQUS软件进行了一系列有限元分析。该研究考察了各种因素,包括PG强度、定向刨花板(OSB)结构和厚度、螺柱强度和厚度、螺杆间距、轴向力比、壁护套覆盖率和高宽比。综上所述,主要发现:PG强度和壁钉厚度对墙体侧移行为有显著影响,而壁护结构对墙体侧移行为影响较小;增大PG强度、墙柱厚度和强度、墙护层厚度、轴力比、墙护层数(无护层、单护层、双护层)或减小自攻螺钉间距和墙高宽比均可提高墙体抗剪能力;增加PG强度、壁厚或减小壁高宽比均可提高墙体的侧刚度和延性;增加墙钉厚度和增加墙护层可以提高墙体的侧移刚度。然而,这会降低墙体的延展性;减小自攻螺杆间距或增大轴力比后,墙体侧刚度和延性均呈现先增大后减小的趋势;增加墙柱强度对墙体的侧移刚度影响不显著,但会降低墙体的延性。最后,将模拟墙体的侧移刚度和抗剪能力与理论值进行了比较,两者吻合较好。Stability and nonlinear vibration characteristics of cantilevered fluid-conveying pipe with nonlinear energy sinkXueping Chang, Xiaoxiang Hongdoi:10.1016/j.tws.2024.111987非线性能量汇悬臂式输液管道的稳定性及非线性振动特性Considering the midline non-expansion theory and nonlinear coordinate method, this paper mainly investigates the stability and nonlinear vibration characteristics of cantilevered fluid-conveying pipe with energy sink. Based on Hamilton 's variational principle, the dynamic equation of a cantilevered pipe conveying fluid with nonlinear energy sink (NES) under pulsating flow is established. The system equation is processed by Galerkin method, a novel matrix equations of single-degree-of-freedom and multi-degree-of-freedom coupling system is established. The results show that the physical factors in the flow pipe system have a great influence on the critical flow velocity of the whole system, comparing with the case of adding NES. Increasing the proportion of the mass of the fluid will have a greater impact on the real part frequency, thereby increasing the critical velocity of the fluid-conveying pipe system. Addition of nonlinear energy sink can significantly suppress the amplitude and decrease the unstable vibration of the pipe.基于中线非膨胀理论和非线性坐标法,研究了带能量槽的悬臂式输液管道的稳定性和非线性振动特性。基于Hamilton变分原理,建立了脉动流下具有非线性能量汇的悬臂管输送流体的动力学方程。采用伽辽金法对系统方程进行处理,建立了一种新的单自由度与多自由度耦合系统的矩阵方程。结果表明,与添加NES的情况相比,流动管道系统中的物理因素对整个系统的临界流速有很大的影响。增加流体的质量比例将对实部频率产生较大的影响,从而提高流体输送管道系统的临界速度。非线性能量汇的加入能显著抑制管道的幅值,降低管道的不稳定振动。来源:复合材料力学仿真Composites FEM

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