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【新文速递】2023年11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 3 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 5 篇

International Journal of Solids and Structures

Hyperspace bounds on mixed mode elastic constants of n-component transversely-isotropic unidirectional materials

Pham Duc-Chinh

doi:10.1016/j.ijsolstr.2023.112584

n 分量横向各向同性单向材料混合模式弹性常数的超空间界限

We consider the general elastic unidirectional composites composed of n transversely-isotropic components (with unidirectional cylindrical boundaries between the phases), which are just macroscopically isotropic in the transverse plane. All 6 mixed-mode elastic constants appear in the complex mixed-mode longitudinal-transverse stress–strain relations (not well-separated into the pure hydrostatic and deviatoric modes as in the usual problems concerning the 3D- or 2D-isotropic bulk and shear moduli). They are subjected to various combination bounds, derived from the minimum energy principles, involving many effective properties simultaneously in the multidimensional-elastic-constant hyperspace. Exploring the possible trial mixed stress–strain modes, we derive from the combination bounds the new sets of bounds, with additional and more refined ones, on all 6 effective mixed-mode longitudinal-transverse constants of the n-component transversely-isotropic unidirectional composites, which improve significantly over the previous results. Refined optimization techniques have been used in conjunction with the iteration procedure. Using Hill relations relating the exact values of some of the effective elastic constants in the two-component case, the bench-mark Paul-Hill-type bounds have also been deduced for all those 6 mixed elastic constants for comparisons with our new bounds (three of them appear to coincide with those of ours, while the others comparatively are near-to-close in numerical examples) in that specific case. Illustrating numerical examples are provided for some two- and multi-component cases. Related to the subject - the matrix approach on bounding elastic anisotropic composites in the literature is critically examined.

我们考虑的是由 n 个横向各向同性成分(各相之间的边界为单向圆柱形)组成的一般弹性单向复合材料,它们在横向平面上只是宏观各向同性。所有 6 个混合模式弹性常数都出现在复杂的纵向-横向混合模式应力-应变关系中(并不像通常的三维或二维各向同性体积模量和剪切模量问题那样,被很好地区分为纯静压模式和偏离模式)。它们受制于各种组合约束,这些约束源于最小能量原则,同时涉及多维弹性常数超空间中的许多有效特性。在探索可能的试验混合应力-应变模式的过程中,我们从组合约束中推导出了新的约束集,并对 n 组横向各向同性单向复合材料的全部 6 种有效混合模式纵向-横向常数进行了补充和完善,与之前的结果相比有了显著改善。结合迭代程序使用了改进的优化技术。利用与双组分情况下某些有效弹性常数精确值相关的希尔关系,还推导出了所有这 6 个混合弹性常数的保罗-希尔型基准边界,以便与我们在该特定情况下的新边界进行比较(其中 3 个似乎与我们的边界相吻合,而其他边界在数值示例中相对接近)。我们还提供了一些双组分和多组分情况的数值示例。与本课题相关的是,我们对文献中关于弹性各向异性复合材料边界的矩阵方法进行了批判性研究。


New buckling solutions of truncated conical shells incorporating pre-buckling nonlinearity

Zhou Chao, Gong Guangping, Chen Liang, Wang Bo, Li Rui

doi:10.1016/j.ijsolstr.2023.112587

包含预屈曲非线性的截顶锥壳新屈曲解法

The pre-buckling nonlinearity is found to have a remarkable effect on both the buckling loads and modes of shells according to the previous studies. In this study, we present a novel accurate buckling analysis of the truncated conical shells under broad boundary constraints incorporating the pre-buckling nonlinearity by a quasilinearization-precise integral method (Q-PIM). Specifically, the nonlinear buckling equations of the shells are transformed into several linear ones by the perturbation and quasilinearization, and they are then solved by the PIM. The produced state transition equations by the PIM are assembled into a global matrix equation, involving the boundary conditions (BCs), to yield the buckling solutions of the shells with or without incorporating the pre-buckling nonlinearity. The convergence study and benchmark buckling solutions verified by the refined finite element method are presented. The quantitative effects of the size parameters and BCs on the nonlinear critical buckling loads as well as the pre-buckling nonlinearity are investigated.

以往的研究发现,预屈曲非线性对壳的屈曲载荷和模式都有显著影响。在本研究中,我们采用准线性化-精确积分法(Q-PIM),结合预屈曲非线性,对宽边界约束下的截顶锥形壳体进行了一种新的精确屈曲分析。具体来说,通过扰动和准线性化将壳体的非线性屈曲方程转化为多个线性方程,然后用 PIM 求解。由 PIM 生成的状态转换方程被组合成一个全局矩阵方程,其中涉及边界条件 (BC),从而得到包含或不包含预屈曲非线性的壳体屈曲解。本文介绍了收敛性研究和通过精炼有限元法验证的基准屈曲解。研究了尺寸参数和 BCs 对非线性临界屈曲载荷以及预屈曲非线性的定量影响。


Rate-dependent peeling behavior of the viscoelastic film-substrate system

Yin Hanbin, Ma Yinji, Feng Xue

doi:10.1016/j.ijsolstr.2023.112588

粘弹性薄膜-基底系统随速率变化的剥离行为

In contrast to the well-understood peeling behavior of an elastic film-substrate system, the peeling behavior of a viscoelastic film bonded to a rigid substrate remains unclear. This paper established a theoretical peeling model, assuming a uniformly distributed cohesive interfacial interaction, to study the steady-state peeling behavior of a viscoelastic film. The rate-dependent behaviors of the steady-state peeling force and cohesive zone length are mainly analyzed in the present paper. It reveals that there exist 3 typical peeling force-peeling velocity relations relying on the viscous dissipation within the film and the rate-dependent extent of the interfacial adhesion. In addition to the film's viscoelasticity and the peeling velocity, the film thickness, interfacial toughness, and interfacial strength are also identified as factors that influence the steady-state peeling force. For the cohesive zone length of peeling a viscoelastic film, the analytical expression is obtained which demonstrates a dependence on peeling velocity, film viscoelasticity, film thickness, interfacial toughness, and interfacial strength. The present theoretical findings are validated by the finite element simulation and are believed to facilitate the fundamental understandings and practical applications for viscoelastic film-substrate systems.

与人们熟知的弹性薄膜-基底系统的剥离行为不同,粘弹性薄膜与刚性基底粘合后的剥离行为仍不清楚。本文建立了一个理论剥离模型,假设界面相互作用为均匀分布的内聚作用,研究粘弹性薄膜的稳态剥离行为。本文主要分析了稳态剥离力和内聚区长度随速率变化的行为。结果表明,存在 3 种典型的剥离力-剥离速度关系,它们分别依赖于薄膜内部的粘滞耗散和与速率相关的界面粘附程度。除了薄膜的粘弹性和剥离速度外,薄膜厚度、界面韧性和界面强度也是影响稳态剥离力的因素。对于粘弹性薄膜剥离时的内聚区长度,得到的分析表达式表明它取决于剥离速度、薄膜粘弹性、薄膜厚度、界面韧性和界面强度。有限元模拟验证了本理论研究结果,相信有助于对粘弹性薄膜-基底系统的基本理解和实际应用。


International Journal of Plasticity

The interface effect on crack nucleation under dwell fatigue loading in dual-phase Ti alloy

Zhang Linglei, Jiang Binbin, Qiu Jianke, Cao Xumeng, Lei Jiafeng, Yang Rui, Du Kui

doi:10.1016/j.ijplas.2023.103816

双相钛合金停留疲劳加载下裂纹成核的界面效应

The microstructure of dual-phase Ti alloys crucially influences the nucleation of dwell fatigue cracks, which is of significance in determining the dwell fatigue life of Ti alloys. However, the microstructure effect on crack nucleation in dwell fatigue is still in dispute, and direct experimental investigation is desired. Here, we report that the probability of dwell fatigue cracks nucleating at grain boundaries between colonies and primary α grains is approximately one-fifth of that nucleating at grain boundaries between primary α grains. Three dislocation reaction mechanisms are determined for dislocation transmission through αs/β interfaces in colonies, two of which strongly obstruct and disperse dislocations, while the third mechanism leads to concentrated slip bands of dislocations during dwell cycle loading. As decreasing the localization of dislocation slips can effectively reduce the stress concentration at grain boundaries in colonies, it significantly decreases the possibility of crack nucleation. This demonstrates a quantitative relationship between the localization of dislocation slips and the probability of dwell-fatigue crack nucleation. The results provide insights into the quantitative analysis of the microstructure effect on crack nucleation in Ti alloys.

双相钛合金的微观结构对驻留疲劳裂纹的成核有着至关重要的影响,这对决定钛合金的驻留疲劳寿命具有重要意义。然而,微观结构对驻留疲劳裂纹成核的影响仍存在争议,需要进行直接的实验研究。在此,我们报告了驻留疲劳裂纹在鲕粒和原生 α 晶粒之间的晶界成核的概率大约是原生 α 晶粒之间的晶界成核概率的五分之一。确定了位错通过菌落中的αs/β界面传输的三种位错反应机制,其中两种机制强烈阻碍和分散位错,而第三种机制则导致位错在停留循环加载期间形成集中的滑移带。由于降低位错滑移的局部性可有效减少晶胞中晶界的应力集中,从而显著降低裂纹成核的可能性。这证明了位错滑移的定位与驻留疲劳裂纹成核概率之间的定量关系。这些结果为定量分析微观结构对钛合金裂纹成核的影响提供了启示。


Thin-Walled Structures

Experimental and numerical investigations towards the lateral torsional buckling of cellular steel beams

Boissonnade Nicolas, Nseir Joanna, Somja Hugues

doi:10.1016/j.tws.2023.111388

对蜂窝钢梁横向扭转屈曲的实验和数值研究

This paper deals with the response of so-called “cellular members” against lateral torsional buckling. These beams comprising regularly-spaced circular web openings are especially used for their high resistance-to-weight ratio, the possibility to integrate service pipes within their height, and for aesthetics. Such profiles usually exhibit a complex behaviour and many potential failure modes, including interactional local/global instability modes. Regarding global instability, the members are usually designed by means of approximate design rules, which often lead to an unduly conservative solution, with beams sometimes showing up to 150% resistance reserves. The present research works aim at improving this situation, through the development of adequate design formulae. In this respect, the present paper reports on investigations led towards improved solutions for cellular members at the experimental and numerical levels. This first paper focuses on experimental activities and on the development and validation of dedicated shell F.E. models. The results of three bending tests on members spanning from 7.5 m to 11 m are reported. Cross-sectional dimensions, material properties and accurate initial geometrical imperfections were measured for each specimen and further introduced in the corresponding F.E. models, which are shown to provide predictions in close agreement with the experimental results. The companion paper [1] further makes use of the F.E. models within extensive parametric studies and proposes a new set of design rules that could be proposed for integration in Eurocode 3.

本文论述了所谓的 "蜂窝构件 "对横向扭转屈曲的响应。这些梁由间隔规则的圆形腹板开口组成,因其阻力重量比高、可在高度范围内集成服务管道以及美观而得到广泛应用。这种型材通常表现出复杂的行为和许多潜在的失效模式,包括交互式局部/整体失稳模式。在全局失稳方面,构件的设计通常采用近似设计规则,这往往会导致解决方案过于保守,梁的抗力储备有时高达 150%。目前的研究工作旨在通过开发适当的设计公式来改善这种状况。在这方面,本文报告了为改进蜂窝构件的解决方案而进行的实验和数值研究。第一篇论文侧重于实验活动以及专用壳体 F.E. 模型的开发和验证。报告了对跨度为 7.5 米至 11 米的构件进行的三次弯曲试验的结果。对每个试样的横截面尺寸、材料特性和精确的初始几何缺陷进行了测量,并将其进一步引入相应的有限元模型,结果表明,这些模型提供的预测结果与实验结果非常吻合。相关论文[1]进一步在广泛的参数研究中使用了 F.E. 模型,并提出了一套新的设计规则,这些规则可纳入欧洲规范 3。


On the coupling of data-driven computing and model-driven computing with CUF-based beam models

Hui Yanchuan, Giunta Gaetano, Liu Xiao, Zheng Jie, Yang Jie, Huang Wei, Carrera Erasmo

doi:10.1016/j.tws.2023.111394

关于数据驱动计算和模型驱动计算与基于 CUF 的波束模型的耦合

In this article, Model-driven (MD) computing and Data-driven (DD) computing mechanics are coupled under the framework of Carrera’s Unified Formulation (CUF) for beam structures A DD CUF-based computing is applied for the sub-domains of the beam under investigation where the material constitutive models are challenging to be obtained, whereas a MD CUF-based computing is used to deal with the remaining sub-domains where a constitutive model is available. By using CUF, under the premise of sufficient accuracy, the computational cost of DD-MD CUF-based models could be reduced compared with DD-MD FEM models where solid elements are used. Several static cases are analysed to demonstrate the accuracy and reliability of the proposed DD-MD CUF-based model by comparing the obtained results with those from the finite element commercial software tools.

在本文中,模型驱动(MD)计算和数据驱动(DD)计算力学在卡雷拉统一公式(CUF)的框架下对梁结构进行了耦合。通过使用 CUF,在足够精确的前提下,与使用实体元素的 DD-MD FEM 模型相比,基于 DD-MD CUF 模型的计算成本可以降低。我们分析了几个静态案例,通过将获得的结果与有限元商业软件工具的结果进行比较,证明了所提出的基于 DD-MD CUF 的模型的准确性和可靠性。


Damage analysis of deployable thin-walled composite shell structure during coiling up

Chang Zhongliang, Zhao Peng, Zhang Zhijun, Zou Guangping, Zhao Pengyuan, Wu Chenchen

doi:10.1016/j.tws.2023.111395

可展开薄壁复合材料壳体结构在卷绕过程中的损伤分析

Thin-walled coilable composite shells have been successfully used in deployable space payloads due to their high storage efficiency and stiffness-to-weight ratio. However, in real-life applications the deployable composite shells requiring repeatable coiling up and deployment are easy to be damaged, and their damage or failure behaviors due to large deformations has been rarely studied. This paper aims to investigate their damage and failure behaviors during the snap through, equal-sense and opposite-sense coiling up. First, multiscale models are established to compute the mechanical properties of plain-woven fabrics and unidirectional prepregs with consideration of stiffness reduction of the composites. Then, damages of each ply within the thin-walled shell are studied during snap through and coiling up. Simultaneously, effects of hub diameter on the damage of the thin-walled shell were investigated, followed by experimental verification using strain gauges and a scanning electron microscope (SEM). Simulation and experimental results show that the dominated damage of the thin-walled shell is failure of matrix. The SEMs of the edge damaged show failures of both resin and carbon fibers. Tensile damages of matrix can be relieved as the increment of the hub diameter, and no obvious failure is observed at the hub diameter of 50 mm.

薄壁可卷绕复合材料壳体具有较高的存储效率和刚度重量比,已成功用于可展开的空间有效载荷。然而,在实际应用中,需要可重复卷绕和展开的可展开复合材料壳体很容易损坏,而对其因大变形而导致的损坏或失效行为的研究却很少。本文旨在研究其在扣穿、等义和反义卷绕过程中的损伤和失效行为。首先,在考虑降低复合材料刚度的情况下,建立多尺度模型来计算平织织物和单向预浸料的力学性能。然后,研究了薄壁壳体内各层在卡入和卷起过程中的损坏情况。同时,研究了轮毂直径对薄壁外壳损坏的影响,并使用应变仪和扫描电子显微镜(SEM)进行了实验验证。模拟和实验结果表明,薄壁外壳的主要损伤是基体的破坏。边缘损坏处的扫描电子显微镜显示树脂和碳纤维都发生了破坏。基体的拉伸损伤可随着轮毂直径的增大而缓解,在轮毂直径为 50 毫米时未观察到明显的破坏。


A dimensionless analytical analysis for buckling and lateral buckling interaction of thin-walled beams with open cross sections

Bakhach Zaenab, Kaimbillah Ahmed El, Hamdaoui Abdellah, Braikat Bouazza, Mohri Foudil, Damil Noureddine

doi:10.1016/j.tws.2023.111396

开放截面薄壁梁屈曲和侧向屈曲相互作用的无量纲分析

This paper investigates the interaction between buckling and lateral buckling of thin-walled beams with arbitrary open cross-section using nonlinear modeling in large rotation and with warping. First, the equilibrium equations have been transformed into dimensionless ones, and within a nonlinear stability model, various dimensionless parameters are introduced to control the interaction between buckling and lateral buckling. In comparison to a reference of literature, this work focuses on the case of arbitrary sections and includes a greater number of higher-order terms in our analysis. These additions have an impact on the coefficients of the stability formula by expanding its applicability to non- symmetric sections. Then, the effect of the different dimensionless parameters, thus introduced on the stability curve, has been studied. The proposed solutions are validated and compared to numerical solutions obtained by a general finite element package including the warping developed by the authors using Asymptotic Numerical Method (ANM) to solve the initial nonlinear equations.

本文利用非线性模型研究了任意开截面薄壁梁在大旋转和翘曲情况下屈曲与侧向屈曲之间的相互作用。首先,将平衡方程转化为无量纲方程,并在非线性稳定性模型中引入各种无量纲参数来控制屈曲和侧向屈曲之间的相互作用。与参考文献相比,本研究侧重于任意截面的情况,并在分析中加入了更多的高阶项。这些新增项扩大了稳定性公式对非对称截面的适用范围,从而对公式系数产生了影响。然后,研究了由此引入的不同无量纲参数对稳定性曲线的影响。提出的解决方案得到了验证,并与作者使用渐近数值法(ANM)求解初始非线性方程的通用有限元软件包(包括翘曲)获得的数值解决方案进行了比较。


A novel non-contact measurement strategy for large-size inflatable structures based on numerical predictions

Gao Weinan, Song Bo, Chen Xueyan, Lin Guochang, Tan Huifeng

doi:10.1016/j.tws.2023.111397

基于数值预测的新型大尺寸充气结构非接触测量战略

The deformation characteristics of expansive inflatable structures, like airships, provide essential data for their operation in the stratosphere. However, due to rapid configuration changes in these structures with fluctuating air pressure, obtaining accurate morphological data quickly during testing can be challenging. This paper presents a precise method for predicting deformation in large-scale inflatable structures. A finite element method was employed to meticulously model the inflatable structure, underpinned by an inflatable ring skeleton support, and predict its potential maximum deformation points. Leveraging this predictive model as a guide, we proposed utilizing a laser scanning technique for non-contact measurements of the anticipated maximum deformation sites, aiming to discern the deformation patterns of the structure under varying air pressures. A good agreement between the non-contact measurement results and the numerical simulations affirms the efficiency and precision of the proposed methodology. This non-contact measurement strategy, grounded in finite element predictions, streamlines the measurement process, economizing on time and reducing complexity. Such an approach promises to be invaluable for expansive structures like airships. Furthermore, the insights derived from this non-contact method will be pivotal for anticipating the mechanical behaviors of full-scale stratospheric airships during their operations and for refining their design models.

膨胀性充气结构(如飞艇)的变形特性为其在平流层中的运行提供了重要数据。然而,由于这些结构会随着气压的波动而迅速发生构型变化,因此在测试过程中快速获取准确的形态数据是一项挑战。本文提出了一种预测大型充气结构变形的精确方法。采用有限元方法对充气结构(由充气环骨架支撑)进行细致建模,并预测其潜在的最大变形点。以这一预测模型为指导,我们建议利用激光扫描技术对预计的最大变形点进行非接触式测量,以辨别结构在不同气压下的变形模式。非接触式测量结果与数值模拟结果之间的良好一致性证实了所建议方法的效率和精确性。这种以有限元预测为基础的非接触式测量策略简化了测量过程,节省了时间并降低了复杂性。这种方法对于飞艇这样的大型结构来说非常有价值。此外,从这种非接触式方法中获得的见解对于预测全尺寸平流层飞艇在运行期间的机械行为以及改进其设计模型至关重要。



来源:复合材料力学仿真Composites FEM
ACTMechanicalSystemDeform疲劳复合材料非线性通用电子ADS裂纹理论材料多尺度控制试验
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【新文速递】2023年11月26日固体力学SCI期刊最新文章

今日更新:International Journal of Solids and Structures 2 篇,Journal of the Mechanics and Physics of Solids 2 篇,Mechanics of Materials 1 篇,Thin-Walled Structures 3 篇International Journal of Solids and StructuresComputational Cosserat periporomechanics for strain localization and cracking in deformable porous mediaXiaoyu Song, Hossein Pashazaddoi:10.1016/j.ijsolstr.2023.112593可变形多孔介质中应变定位和开裂的 Cosserat 周缘力学计算Strain localization and cracking in porous media are significant issues in engineering and science. Periporomechanmics is a strong nonlocal framework for modeling the mechanics and physics of porous media with evolving discontinuities. In periporomechanics, the horizon that usually lacks a physical meaning serves as a nonlocal parameter. In this article, as a new contribution, we formulate a Cosserat periporomechanics paradigm incorporating a micro-structure related length scale for modeling shear banding and cracking in dry porous media. In this new Cosserat-periporomechanics framework, each material point is endowed with both translational and rotational degrees of freedom following the Cosserat continuum theory. We formulate a stabilized Cosserat constitutive correspondence principle through which classical micro-polar constitutive models for porous media can be used in Cosserat periporomechanics. We have numerically implemented the Cosserat periporomechanics paradigm through an explicit Lagrangian meshfree algorithm. We first present numerical examples to validate the implemented computational Cosserat periporomechanics paradigm for modeling shear bands and cracks. We then present numerical examples to demonstrate the efficacy and robustness of the Cosserat periporomechanics for modeling the shear banding bifurcation and crack branching in dry porous media.多孔介质中的应变局部化和开裂是工程和科学领域的重大问题。周界力学是一个强大的非局部框架,用于模拟具有不断变化的非连续性的多孔介质的力学和物理学。在周界力学中,通常缺乏物理意义的地平线可作为非局部参数。在本文中,作为一项新贡献,我们提出了一种 Cosserat 周缘力学范式,该范式结合了与微结构相关的长度尺度,用于模拟干燥多孔介质中的剪切带和裂缝。在这一新的 Cosserat 周缘力学框架中,每个材料点都被赋予了 Cosserat 连续理论的平移和旋转自由度。我们提出了一个稳定的 Cosserat 构成对应原理,通过该原理,多孔介质的经典微极性构成模型可用于 Cosserat 周界力学。我们通过显式拉格朗日无网格算法,在数值上实现了 Cosserat 周缘力学范式。我们首先通过数值示例验证了用于剪切带和裂缝建模的 Cosserat 周缘力学计算范式。然后,我们以数值实例证明了 Cosserat 周缘力学在干多孔介质剪切带分叉和裂缝分支建模中的有效性和稳健性。Determination of flexoelectric coefficients of higher-order continuum theories from CsCl lattice modelMoonhong Kim, Seunghun Lee, Dongwoo Sohn, Hyun-Gyu Kimdoi:10.1016/j.ijsolstr.2023.112596从氯化铯晶格模型确定高阶连续理论的柔电系数Flexoelectricity is an electromechanical coupling phenomenon between inhomogeneous deformation and electric polarization. The classical theory, which relies on the strain, is insufficient for representing flexoelectricity. Instead, a higher-order continuum theory that employs a measure capable of expressing local inhomogeneous deformation is necessary. In the present work, we concatenate higher-order continuum theories with a CsCl lattice structure consisting of charged particles and determine the resulting constitutive coefficients for higher-order continuum theories. First, we derived continuum internal energy density functions for dielectrics from the conservation laws. We consider two different higher-order continuum theories: coupled stress and strain gradient theories. Second, we present a procedure for determining the coefficients of higher-order continuum theories by using a discrete lattice model under the assumption that the internal energies of the lattice and continuum models are the same for identical deformations. To validate the coefficients, three sample problems are examined by presenting their analytical solutions. The results of sample problems demonstrate that the two higher-order theories can provide quantitative information about the size and flexoelectric effects. In particular, the strain gradient theory predicts the deformation of the lattice structure more accurately.挠电是不均匀变形与电极化之间的一种机电耦合现象。依靠应变的经典理论不足以表现挠电现象。取而代之的是一种高阶连续理论,它采用了一种能够表达局部不均匀变形的量度。在本研究中,我们将高阶连续理论与由带电粒子组成的氯化铯晶格结构结合起来,并确定了由此产生的高阶连续理论的构成系数。首先,我们根据守恒定律推导出了电介质的连续内能密度函数。我们考虑了两种不同的高阶连续理论:耦合应力和应变梯度理论。其次,我们提出了一种通过使用离散晶格模型来确定高阶连续理论系数的程序,该程序的假设是,在相同变形情况下,晶格模型和连续模型的内能是相同的。为了验证这些系数,我们对三个示例问题进行了研究,并给出了它们的分析解。样本问题的结果表明,两种高阶理论可以提供有关尺寸和挠电效应的定量信息。尤其是应变梯度理论能更准确地预测晶格结构的变形。Journal of the Mechanics and Physics of SolidsInfluence of nearby fiber on fiber–matrix debonding: Coupled Criterion prediction and debonding shape determinationH. Girard, A. Doitrand, B. Koohbor, R.G. Rinaldi, N. Godin, D. Long, J. Bikarddoi:10.1016/j.jmps.2023.105498附近纤维对纤维-基体脱粘的影响:耦合标准预测和脱胶形状确定Fiber-matrix interface debonding in two-fiber specimens under remote tensile loading is studied both experimentally and numerically by means of a coupled stress and energy criterion. Depending on its relative position, the neighboring fiber induces a perturbation of both stress and energy fields at the reference fiber interface which results in asymmetrical debonding initiation and propagation. The determination of the debonding initiation and propagation shape is addressed based on either (i) stress isocontours, (ii) energy isocontours or (iii) the Coupled Criterion (CC). It was found that the debonding initiation configuration can be determined based on stress (respectively energy) isocontours for small (respectively large) enough interface brittleness number. For intermediate brittleness number, the debonding initiation configuration cannot be obtained using neither the stress nor the energy isocontours, but requires a coupling of both aspects. Despite different initiation debonding configurations, the corresponding initiation remote stresses do not differ much, which results in similar debonding configurations after unstable crack propagation following initiation.通过应力和能量耦合准则,对远程拉伸加载下双纤维试样中的纤维-基体界面剥离进行了实验和数值研究。根据其相对位置,邻近纤维会在参考纤维界面上引起应力场和能量场的扰动,从而导致非对称的脱粘开始和传播。脱粘开始和传播形状的确定基于 (i) 应力等值线、(ii) 能量等值线或 (iii) 耦合准则 (CC)。研究发现,在界面脆性数足够小(分别为足够大)的情况下,可以根据应力(分别为能量)等值线确定脱粘起始构型。对于中等脆性数,既不能使用应力等值线,也不能使用能量等值线,而是需要将这两方面耦合起来,才能获得脱粘起始构型。尽管起始脱粘构型不同,但相应的起始远应力差别不大,这就导致起始后裂纹不稳定扩展后的脱粘构型相似。A theoretical model to determine solid surface tension through droplet on film configuration and experimental verificationFeng Du, Pengyu Lv, Hongyuan Li, Jianxiang Wang, Li-Hua Shaodoi:10.1016/j.jmps.2023.105504通过膜上液滴构型确定固体表面张力的理论模型及实验验证Determination of the surface tension of solids has been a challenging issue. This work presents an approach to the issue based on the configuration of a droplet spreading on a free standing film. Firstly, a theoretical model for the equilibrium configuration of a droplet spreading on a film is developed, which reveals that the surface elasticity has little contribution to the equilibrium configuration, and the effective strain of the film is determined by the bulge angle analytically. Based on these observations, a new procedure is presented to measure the surface tension of the film through droplet loading, which is realized by extrapolating the film tension as a function of the product of the film thickness and the effective strain. Finally, as a validation, we use this approach to extract the surface tension of soft elastomers. This work provides a viable and robust approach to determination of the surface tension of solids.固体表面张力的测定一直是一个具有挑战性的问题。这项研究提出了一种基于液滴在独立薄膜上扩散的构型来解决这一问题的方法。首先,建立了液滴在薄膜上扩散的平衡构型理论模型,发现表面弹性对平衡构型的贡献很小,薄膜的有效应变由凸起角分析确定。基于这些观察结果,我们提出了一种通过液滴加载测量薄膜表面张力的新程序,该程序通过将薄膜张力推断为薄膜厚度和有效应变乘积的函数来实现。最后,作为验证,我们使用这种方法提取软弹性体的表面张力。这项工作为测定固体表面张力提供了一种可行且稳健的方法。Mechanics of MaterialsNanoscale dynamic mechanical analysis of a viscoelastic matrix inclusion within an elastic substrateOfer Braunshtein, Yaniv Shelef, Benny Bar-Ondoi:10.1016/j.mechmat.2023.104873对弹性基底中的粘弹性基质包含物进行纳米级动态力学分析Advanced composite materials incorporate viscoelastic matrix inclusions in designated locations within elastic substrates, which grant them specialized energy dissipation capabilities of dynamic loadings. Identifying the local nanomechanical properties of the matrix-substrate complex within the composite is critical to its design and adaptation toward a specific target function. Here, we conduct FE simulations of nanoscale dynamic mechanical analysis (DMA) testing on hemispherical matrix inclusions within elastic substrates and analyze the variations in its indentation storage loss moduli measures for different matrix-substrate configurations. Then, we describe the mechanical system by simple spring models, identify the dominating parameters at different contact states of the nanoscale DMA testing, and obtain highly accurate analytical formulae that link the indentation measures of the matrix-substrate complex to the individual mechanical properties of the matrix and substrate parts. Our analysis can be directly integrated into benchmark nanomechanical testing methodologies of composite materials and promotes the local dynamic-mechanical characterization of complex materials systems, including nanomaterials, micro-architected structures, and bio-inspired designs.先进的复合材料在弹性基体的指定位置加入粘弹性基体夹杂物,使其在动态载荷下具有特殊的能量消耗能力。确定复合材料中基质-基底复合体的局部纳米力学性能,对其设计和适应特定目标功能至关重要。在此,我们对弹性基底中的半球形基质夹杂物进行了纳米级动态力学分析(DMA)测试的有限元模拟,并分析了不同基质-基底配置下压痕存储损耗模量的变化。然后,我们用简单的弹簧模型描述了机械系统,确定了纳米级 DMA 测试中不同接触状态下的主导参数,并获得了高精度的分析公式,将基体-基底复合体的压痕测量值与基体和基底部分的单个机械特性联系起来。我们的分析可直接集成到复合材料的基准纳米力学测试方法中,并促进复杂材料系统(包括纳米材料、微架构结构和生物启发设计)的局部动态力学表征。Thin-Walled StructuresAnalysis on aeroelastic stability of rectangular-planed air-supported membrane structuresKeye Yan, Yue Wu, Zhaoqing Chen, Junbin Zhaodoi:10.1016/j.tws.2023.111416矩形平面气撑膜结构的气弹稳定性分析This research investigates aeroelastic stability of rectangular air-supported membrane structures subjected to wind actions. By employing potential theory to tackle air flows, the relations between extra aerodynamic forces and structural motions are resolved through the utilization of the boundary element method and the finite element method, capturing the complexities associated with structural geometries and wind pressure distributions. By combining these extra aerodynamic forces with structural dynamic equilibrium equations, critical instability wind velocities for various structural vibration modes are derived. The simulation results are validated through aeroelastic wind tunnel tests, demonstrating a close alignment between the numerical findings and experimental observations in terms of the critical wind velocity and the corresponding instability mode. Additionally, the study analyzes influences of structural geometric configurations, internal pressures, and membrane tensile stiffness on the critical instability wind velocities and corresponding instability modes. It is observed that lower aspect ratios, smaller structural spans, higher internal pressures, and greater membrane tensile stiffness can increase the critical instability wind velocity, corresponding to variations in critical instability mode shapes. Results obtained from this research are expected to provide guidance for the development of wind-resistant designs for air-supported membrane structures.本研究探讨了矩形气撑膜结构在风力作用下的气动弹性稳定性。通过采用势理论处理气流,利用边界元法和有限元法解决了额外气动力和结构运动之间的关系,捕捉到了与结构几何形状和风压分布相关的复杂性。通过将这些额外的空气动力与结构动态平衡方程相结合,得出了各种结构振动模式的临界失稳风速。通过气动弹性风洞试验对模拟结果进行了验证,结果表明在临界风速和相应的失稳模式方面,数值结果与实验观测结果非常吻合。此外,研究还分析了结构几何配置、内部压力和膜拉伸刚度对临界失稳风速和相应失稳模式的影响。研究发现,较低的长宽比、较小的结构跨度、较高的内部压力和较大的膜拉伸刚度都会提高临界失稳风速,从而导致临界失稳模式形状的变化。这项研究的结果有望为开发空气支撑膜结构的抗风设计提供指导。Dynamic modeling and simulation for pneumatic landing airbag system with frictional contactBo Lei, Tingting Yuan, Jinyang Liu, Caishan Liudoi:10.1016/j.tws.2023.111417带摩擦接触的气动着陆安全气囊系统的动态建模与仿真The landing airbag system is a mechanism composed of thin-walled structures designed to ensure the safe landing of a lander. To investigate the dynamic behavior of the landing airbag with large deformations, a novel modeling approach incorporating gas exchange and frictional contact is proposed. The Absolute Nodal Coordinate Formulation (ANCF) is introduced to model the flexible airbag. Subsequently, the gas parameters inside the airbag are calculated by integrating the Control Volume (CV) Method and the energy conservation equation. Additionally, based on master–slave techniques, a frictional contact formulation for the thin-walled structure and the rigid plane is presented, in which the normal contact force is estimated using the penalty method, and the velocity-based friction model accounting for the stick–slip transition characterizes the tangential friction. Furthermore, the bounding box technology is adopted to improve contact detection efficiency. A series of numerical examples are performed, which demonstrates the proposed model’s advantages in terms of precision and versatility. Finally, the landing dynamic characteristics of the airbag landing system for the small lunar lander are successfully revealed, and the parameter analysis for the airbag system is expected to aid the design optimization of the airbag cushioning system.着陆气囊系统是一种由薄壁结构组成的装置,旨在确保着陆器安全着陆。为了研究着陆气囊在大变形情况下的动态行为,提出了一种包含气体交换和摩擦接触的新型建模方法。该方法引入了绝对节点坐标公式(ANCF)来模拟柔性气囊。随后,通过整合控制体积(CV)法和能量守恒方程,计算出安全气囊内部的气体参数。此外,基于主从技术,提出了薄壁结构与刚性平面的摩擦接触公式,其中法向接触力使用惩罚法估算,而基于速度的摩擦模型考虑了粘滑过渡,表征了切向摩擦。此外,还采用了边界框技术来提高接触检测效率。通过一系列数值示例,证明了所提模型在精度和通用性方面的优势。最后,成功揭示了小型月球着陆器气囊着陆系统的着陆动态特性,气囊系统的参数分析有望帮助气囊缓冲系统的优化设计。Analysis of Negative Stiffness Structures with B-spline Curved BeamsSize Ai, Jianzheng Wei, Zhimin Xie, Huifeng Tandoi:10.1016/j.tws.2023.111418利用 B-样条曲线梁分析负刚度结构With unique mechanical properties, negative stiffness (NS) structures have presented significant advantages in energy absorption. In recent years, NS structures consisting of periodically arranged curved beams have attracted comprehensive attention. However, the curved beams of the current report mainly focus on geometrical parameters in specific configurations, and the variety of the reported geometrical configurations of the flexible beams is relatively limited. In this paper, a B-spline curved beam design method is proposed. A static analysis model of a B-spline curved beam is developed to investigate the force-displacement relations of curved beams in different configurations. The configuration for the B-spline curved beam is obtained, and the relation between the geometric parameters and the mechanical properties of the B-spline curved beam is discussed. Then the mechanical properties of NS structures with periodically arranged B-spline curved beams are analyzed by the finite element method (FEM), and the experiments verified the correctness of the simulation method. Finally, the force-displacement relation and energy-absorption properties of gradient NS structures with B-spline curved beams are discussed. The results indicate that the NS structure with B-spline curved beams has repeatability and effective energy absorption properties. The deformation form of the NS structure can be modulated by gradient NS design, and the energy absorption properties of the NS structure can be improved effectively. The research can provide a reference for the design of NS structures.负刚度(NS)结构具有独特的机械特性,在能量吸收方面具有显著优势。近年来,由周期性排列的曲线梁组成的负刚度结构引起了广泛关注。然而,目前所报道的曲线梁主要集中在特定配置的几何参数上,所报道的柔性梁的几何配置种类相对有限。本文提出了一种 B-样条曲线梁设计方法。建立了 B-样条曲线梁的静态分析模型,以研究不同配置下曲线梁的力-位移关系。得到了 B-样条曲线梁的构型,并讨论了 B-样条曲线梁的几何参数与力学性能之间的关系。然后用有限元法(FEM)分析了周期性布置 B-样条曲线梁的 NS 结构的力学性能,并通过实验验证了模拟方法的正确性。最后,讨论了带有 B-样条曲线梁的梯度 NS 结构的力-位移关系和能量吸收特性。结果表明,带 B-样条曲线梁的 NS 结构具有可重复性和有效的能量吸收特性。通过梯度 NS 设计可以调节 NS 结构的变形形式,有效改善 NS 结构的能量吸收性能。该研究可为 NS 结构的设计提供参考。来源:复合材料力学仿真Composites FEM

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