【新文速递】2023年9月27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，Mechanics of Materials 2 篇，Thin-Walled Structures 2 篇

International Journal of Solids and Structures

A consistent multiscale mechanical formulation for media with randomly distributed voids

Blanco P.J., Sánchez P.J., Rocha F.F., Toro S., Feijóo R.A.

doi:10.1016/j.ijsolstr.2023.112494

具有随机分布空隙的介质的一致多尺度力学公式

In this work we are interested in constructing a multiscale framework for solid media featuring a random distribution of voids. The reliability of standard lower bound multiscale models is questionable when voids reach the boundary, and the problem becomes critical when they are randomly arranged over the micro-cell (MC) boundary, such that periodic boundary conditions are not an option to be considered. This work presents a novel multiscale mechanical formulation to model the material behavior of media featuring such kind of heterogeneous constitution. The multiscale model is built within the framework posited by the Method of Multiscale Virtual Power. The original contribution lies at the core of the gradient homogenization formula, which generalizes existing strategies. Such generalized homogenization approach results in new Minimally Constrained Kinematical Multiscale Model (MCKMM). Moreover, alternative -kinematically more constrained with respect to the MCKMM- boundary conditions are proposed in order to obtain a wide family of multiscale sub-models (characterized by corresponding sub-spaces of the space associated with the minimally constrained model), which can be useful in practical applications. Numerical experiments are reported that provide support to the concepts introduced in this work.

在这项研究中，我们希望为具有随机空隙分布的固体介质构建一个多尺度框架。当空隙到达边界时，标准下限多尺度模型的可靠性就会受到质疑，而当空隙在微单元（MC）边界上随机分布时，问题就变得非常严重，因为周期性边界条件是无法考虑的。本研究提出了一种新颖的多尺度力学模型，用于模拟具有此类异质结构的介质的材料行为。多尺度模型是在多尺度虚拟力量方法的框架内建立的。其原创性贡献在于梯度均质化公式的核心，该公式对现有策略进行了概括。这种广义同质化方法产生了新的最小约束运动学多尺度模型（MCKMM）。此外，还提出了与 MCKMM 相比在运动学上更受约束的替代边界条件，以获得广泛的多尺度子模型系列（以与最小约束模型相关的空间的相应子空间为特征），这些子模型在实际应用中非常有用。报告中的数值实验为本研究提出的概念提供了支持。

Mechanics of Materials

Improved XFEM for 3D interfacial crack modeling

Deng Huachao, Yan Bo, Koyanagi Jun

doi:10.1016/j.mechmat.2023.104811

用于三维界面裂纹建模的改进型 XFEM

The conventional extended finite element method (XFEM) usually suffers from the crack tip enrichment for removing the blending elements. This may be inconvenient when treating the three dimensional (3D) and curved crack modeling since the crack tip enrichment is usually defined in the local coordinate system depending on the crack front. To avoid these shortcomings of the XFEM, an improved enrichment scheme is proposed for the 3D interfacial crack modeling. The proposed enrichment scheme removes the crack tip enrichment and two weight functions are introduced to capture the strong and weak discontinuities in the element including the crack front. The new enrichment scheme has advantages for the 3D curved interfacial cracks since all the enrichment functions are defined in the global system and it is unnecessary to introduce additional coordinate systems. Several benchmark problems including the mixed mode stress intensity factors (SIFs), anti-plane load and curved cracks are analyzed by the proposed method with the local refinement technology. Numerical results demonstrate that the proposed method can obtain accurate 3D energy release rate and SIFs. In addition, the proposed method enhances the applications of XFEM and has the potential abilities to the multiple-fields coupling and interfacial crack growth phenomena due to the fact that compatible enrichment functions are utilized.

传统的扩展有限元法（XFEM）在去除混合元素时通常会受到裂纹尖端富集的影响。这在处理三维（3D）和弯曲裂纹建模时可能会带来不便，因为裂纹尖端富集通常是根据裂纹前沿在局部坐标系中定义的。为了避免 XFEM 的这些缺点，我们提出了一种改进的三维界面裂纹建模富集方案。所提出的富集方案取消了裂纹尖端富集，并引入了两个权重函数来捕捉元素（包括裂纹前沿）中的强不连续性和弱不连续性。新的富集方案对于三维曲面界面裂缝具有优势，因为所有富集函数都是在全局系统中定义的，无需引入额外的坐标系。所提出的方法采用局部细化技术分析了几个基准问题，包括混合模式应力强度因子 (SIF)、反平面载荷和弯曲裂缝。数值结果表明，所提出的方法可以获得精确的三维能量释放率和 SIF。此外，由于使用了兼容的富集函数，所提出的方法增强了 XFEM 的应用，并具有处理多场耦合和界面裂纹生长现象的潜在能力。

Effect of biaxial cyclic loading path on the mechanical and microstructure properties of articular cartilage

Gao Lilan, Feng Luming, Tan Yansong, Gao Qijun, Liu Gang, Zhang Chunqiu

doi:10.1016/j.mechmat.2023.104812

双轴循环加载路径对关节软骨机械和微观结构特性的影响

Cyclic loading stimulation has the potential to change both the mechanical properties and microstructure of cartilage, subsequently damaging the articular cartilage and contributing to joint osteoarthritis. This study focuses on investigating the behavior of knee articular cartilage under biaxial cyclic loading and analyzing the associated microstructural changes at the ultrastructural level. We studied the in-plane biaxial cyclic loading behavior of cartilage with a particular emphasis on understanding the effects of loading paths, taking into consideration the complex loading conditions encountered during daily activities. The experimental results reveal a clear influence of the constraints in the Y-direction (orthogonal direction) on the strain evolution in the X-direction. Furthermore, the variation in orthogonal stress corresponding to the loading path significantly impacts the biaxial mean strain of the test sample. To be specific, the uniaxial path, characterized by no constraints in the Y-direction, demonstrates the highest mean strain of 25.08 ± 0.88% in the X-direction, while the proportional path exhibits the lowest mean strain (10.77 ± 0.49%) in the X-direction due to the Y-direction's largest stress constraint. We explored the effects of stress amplitude and peak stress holding time on mean strain under a square path. Our observations indicate that the mean strain of cartilage increases with the higher stress amplitude or the longer peak stress holding time. Additionally, we analyzed the collagen fibril networks before and after biaxial cyclic loading to reveal the intrinsic deformation mechanism. The rearrangement of collagen fibril networks is closely associated with the stress state of cartilage, where higher stress levels lead to more severe fibril damage.

循环加载刺激有可能改变软骨的机械性能和微观结构，进而损伤关节软骨并导致关节骨关节炎。本研究重点研究膝关节软骨在双轴循环加载下的行为，并在超微结构层面分析相关的微观结构变化。考虑到日常活动中遇到的复杂加载条件，我们研究了软骨在平面内的双轴循环加载行为，重点是了解加载路径的影响。实验结果表明，Y 方向（正交方向）的约束对 X 方向的应变演变有明显影响。此外，加载路径对应的正交应力变化对测试样本的双轴平均应变有显著影响。具体来说，单轴路径的特点是在 Y 方向上没有限制，在 X 方向上表现出最高的平均应变（25.08 ± 0.88%），而比例路径由于 Y 方向的应力限制最大，在 X 方向上表现出最低的平均应变（10.77 ± 0.49%）。我们探讨了应力振幅和峰值应力保持时间对方形路径下平均应变的影响。我们的观察结果表明，软骨的平均应变随着应力振幅越大或峰值应力保持时间越长而增加。此外，我们还分析了双轴循环加载前后的胶原纤维网络，以揭示其内在变形机制。胶原纤维网络的重新排列与软骨的应力状态密切相关，应力水平越高，纤维损伤越严重。

Thin-Walled Structures

Non-destructive characterization of cylindrical shells by probing: Identification of the probing location from energy barrier and probing forces using Measured Geometric Imperfections (MGI)

Ankalkhope Suhas, Jose Sandeep

doi:10.1016/j.tws.2023.111232

通过探测对圆柱形外壳进行非破坏性鉴定：利用测量的几何缺陷 (MGI) 从能量屏障和探测力识别探测位置

In the present study, the prediction of the critical buckling load of an axially compressed cylindrical shell is investigated based on the novel non-destructive probing method with the aid of Measured Geometric Imperfections (MGI). A laser point scanner is used to obtain the imperfection data. The imperfection data is analyzed to find a sample space of points where the buckling is likely to initiate. The optimum location for probing is determined from the sample set by finding the Least Resistance Path (LRP) to probing using two methods, one based on the Energy barrier and the other from the reaction forces observed corresponding to deep probe advancements. It is found that MGI can aid the procedure by improving the selection of the probing points and hence the prediction accuracy; However, MGI does not eliminate the need for multiple probing. The study has shown the possibility of obtaining multiple probing locations that can predict the peak load within acceptable levels of accuracy.

在本研究中，利用测量几何缺陷 (MGI) 的新型无损探测方法，对轴向压缩圆柱形壳体的临界屈曲载荷进行了预测。使用激光点扫描仪获取缺陷数据。对缺陷数据进行分析，以找到可能发生屈曲的点的样本空间。根据样本集确定最佳探测位置，方法是使用两种方法找到探测的最小阻力路径 (LRP)，其中一种方法基于能量屏障，另一种方法基于探测深度前进时观察到的反作用力。研究发现，MGI 可以改进探测点的选择，从而提高预测准确性，从而有助于该过程；但是，MGI 并不能消除多次探测的需要。研究表明，可以获得多个探测点，从而在可接受的精度范围内预测峰值载荷。

Nonlinear Large-Amplitude Vibration Analysis of Annular Sector Plates Made of FGMs Subjected to Cooling Shock

Ansari R., Zargar Ershadi M., Akbardoost Laskoukalayeh H., Rouhi H.

doi:10.1016/j.tws.2023.111233

受冷却冲击的 FGM 环形扇形板的非线性大振幅振动分析

A numerical approach is developed in the present article to study the geometrically nonlinear vibrations of annular sector plates made of functionally graded materials (FGMs) due to being exposed to cooling shock. The first-order shear deformation plate theory (FSDT) is used in the modeling of plate, and governing equations of motion are derived based on Hamilton's principle considering von Kármán nonlinear kinematic relations. It is also considered that the properties of FGMs are dependent on temperature and distribution of materials. According to the uncoupled thermoelasticity theory, the temperature distribution is obtained via 1D Fourier-type transient heat conduction equation. To numerically solve the problem, the generalized differential quadrature (GDQ) method and Newmark-beta integration scheme are utilized. Considering two different types of thermal loading as cooling shock, the effects of various parameters including thermal load rapidity time, geometry, magnitude of thermal load and material properties on the large-amplitude vibrations of annular sector plates are investigated.

本文开发了一种数值方法来研究由功能分级材料（FGMs）制成的环形扇形板在受到冷却冲击时产生的几何非线性振动。在板的建模中使用了一阶剪切变形板理论（FSDT），并根据汉密尔顿原理（考虑到 von Kármán 非线性运动学关系）推导出了支配运动方程。同时还考虑到 FGM 的特性取决于温度和材料分布。根据非耦合热弹性理论，温度分布可通过一维傅里叶型瞬态热传导方程获得。为了对问题进行数值求解，采用了广义微分正交（GDQ）方法和 Newmark-beta 积分方案。考虑到两种不同类型的热负荷作为冷却冲击，研究了热负荷快速时间、几何形状、热负荷大小和材料特性等各种参数对环形扇形板大振幅振动的影响。

来源：复合材料力学仿真Composites FEM

【新文速递】2023年9月22日固体力学SCI期刊最新文章

International Journal of Solids and StructuresGraphic statics and symmetrySchulze Bernd, Millar Camerondoi:10.1016/j.ijsolstr.2023.112492图形静力学和对称性Reciprocal diagrams are a geometric construction dating back to Maxwell and Cremona in which a self-stressed plane framework with a planar graph is paired with another self-stressed reciprocal framework on the dual graph. Either one of the reciprocal frameworks is the form diagram of a self-stressable structure and the other is the force diagram of the corresponding axial forces. This geometric technique offers insights into the self-stresses and infinitesimal motions (mechanisms) of both frameworks in the reciprocal pair. For a symmetric framework with a fully-symmetric self-stress, we obtain an equi-symmetric reciprocal pair of plane frameworks, as well as the associated symmetric discrete dual Airy stress function polyhedra. In this paper we exploit symmetry to refine the Maxwell-Cremona correspondence by considering the decomposition of the self-stress and motion spaces into invariant subspaces corresponding to the irreducible representations of the symmetry group. As such, the familiar s = m∗ + 1 relationship for the number of self-stresses of a framework, s, and the number of mechanisms of the reciprocal,m*, is reworked into a symmetry adapted version which provides greater insights into the properties of the reciprocal framework pair. We also show how the quotient graph of a symmetric framework and its reciprocal can be used to efficiently detect infinitesimal motions, self-stresses and polyhedral liftings of different symmetry types. This allows for symmetry-adapted simplified structural analyses of symmetric structures.互易图是一种几何结构，可追溯到麦克斯韦和克雷莫纳，其中平面图上的自应力平面框架与对偶图上的另一个自应力互易框架配对。其中任何一个互易框架都是自应力结构的形式图，而另一个互易框架则是相应轴向力的力图。通过这种几何技术，可以深入了解互对框架中两个框架的自应力和无限小运动（机制）。对于具有完全对称自应力的对称框架，我们可以得到等对称互对平面框架，以及相关的对称离散双 Airy 应力函数多面体。在本文中，我们考虑将自应力和运动空间分解为对应于对称群不可还原表示的不变子空间，从而利用对称性来完善麦克斯韦-克雷莫纳对应关系。因此，我们所熟悉的s = m∗ + 1框架自应力的数量关系、s与倒数的机制数之间的 + 1 关系、m*的商图被重新制作成一个对称性适应版本，该版本能让我们更深入地了解互易框架对的特性。我们还展示了如何利用对称框架及其倒数的商图来有效检测不同对称类型的无限小运动、自应力和多面体提升。这样就可以对对称结构进行对称适配的简化结构分析。International Journal of PlasticityThe Mechanism for Li-addition Induced Homogeneous Deformation in Mg-4.5 wt. % Li AlloyXu Jing, Guan Bo, Xin Yunchang, Li Xiao, Wu Peidong, Huang Xiaoxu, Liu Qingdoi:10.1016/j.ijplas.2023.103763镁-4.5 wt%锂合金中锂离子添加诱导均匀变形的机理The mechanism by which Li additions induce a more homogeneous deformation was systematically investigated in this study by comparing the deformation behavior of pure Mg and Mg-4.5 wt. % Li using experiments, crystal plasticity simulations, and theoretical calculations. The results of the digital image correlation measurements showed that under tension along the transverse direction (TD), strong localized deformation bands with an angle of approximately 20° with respect to the TD were observed in pure Mg, but were absent in Mg-4.5 wt. % Li. Slip trace analyses indicated that basal slip was the predominant deformation mode for pure Mg, whereas that for Mg-4.5 wt. % Li was prismatic slip. A high relative activity of pyramidal slip, approximately 17%, was observed in Mg-4.5 wt. % Li at a high strain of 10%. Contraction or double twins were hardly detected during the entire tension process. Crystal plasticity simulations revealed that the 4.5 wt. % Li addition dramatically reduced the critical resolved shear stress (CRSS) ratio of pyramidal slip: prismatic slip: basal slip, which was 31.5:21:1 for pure Mg and 4.3:1.3:1 for Mg-4.5 wt. % Li. Theoretical calculations using the CRSS ratios determined by simulations revealed that easy and uniform deformation propagation induced by a dramatically reduced CRSS ratio of prismatic slip to basal slip played a more important role in improving the deformation homogeneity, in addition to the enhanced activity of pyramidal slip. The mechanisms for how Li additions improve the ductility of Mg are also revisited in this paper.本研究通过实验、晶体塑性模拟和理论计算，比较了纯镁和 Mg-4.5 wt. % Li 的变形行为，系统地研究了锂添加物诱导更均匀变形的机制。数字图像相关测量的结果表明，在沿横向（TD）拉伸的情况下，在纯镁中观察到与 TD 成约 20° 角的强局部变形带，但在 Mg-4.5 wt.滑移痕量分析表明，基底滑移是纯镁的主要变形模式，而镁-4.5 wt.在 10%的高应变下，Mg-4.5 wt. % Li 中的金字塔滑移相对活跃度较高，约为 17%。在整个拉伸过程中几乎检测不到收缩或双孪晶。晶体塑性模拟显示，4.5 wt. % Li 的添加大大降低了金字塔滑移：棱柱滑移：基底滑移的临界解析剪切应力（CRSS）比，纯 Mg 为 31.5:21:1，而 Mg-4.5 wt. % Li 为 4.3:1.3:1。利用模拟确定的 CRSS 比进行的理论计算显示，棱柱滑移与基底滑移的 CRSS 比急剧下降所引起的易于均匀变形传播，除了增强金字塔滑移的活性外，在改善变形均匀性方面发挥了更重要的作用。本文还重新探讨了添加锂如何改善镁的延展性的机制。来源：复合材料力学仿真Composites FEM