【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 Structures

Computational Cosserat periporomechanics for strain localization and cracking in deformable porous media

Xiaoyu Song, Hossein Pashazad

doi: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 model

Moonhong Kim, Seunghun Lee, Dongwoo Sohn, Hyun-Gyu Kim

doi: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 Solids

Influence of nearby fiber on fiber–matrix debonding: Coupled Criterion prediction and debonding shape determination

H. Girard, A. Doitrand, B. Koohbor, R.G. Rinaldi, N. Godin, D. Long, J. Bikard

doi: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 verification

Feng Du, Pengyu Lv, Hongyuan Li, Jianxiang Wang, Li-Hua Shao

doi: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 Materials

Nanoscale dynamic mechanical analysis of a viscoelastic matrix inclusion within an elastic substrate

Ofer Braunshtein, Yaniv Shelef, Benny Bar-On

doi: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 Structures

Analysis on aeroelastic stability of rectangular-planed air-supported membrane structures

Keye Yan, Yue Wu, Zhaoqing Chen, Junbin Zhao

doi: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 contact

Bo Lei, Tingting Yuan, Jinyang Liu, Caishan Liu

doi: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 Beams

Size Ai, Jianzheng Wei, Zhimin Xie, Huifeng Tan

doi: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。