【新文速递】2023年12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 1 篇

International Journal of Solids and Structures

Computational and physical aspects for the occurrence of crease in an elastomer under general loading conditions

Seishiro Matsubara, Atsuya Ogino, So Nagashima, Dai Okumura

doi:10.1016/j.ijsolstr.2023.112610

弹性体在一般加载条件下出现皱褶的计算和物理问题

We study the occurrence of crease in an elastomer under three loading conditions from both computational and physical points of view. A two-dimensional finite element analysis, including a perturbation force–based approach, is performed to detect the stable creased state, where the crease formation is completed. A mesh convergence study for the energy release and crease depth in the creased state provides a guideline for the finite element mesh requisite for predicting the occurrence of crease. We also visualize the mesh convergence for the critical creasing onset by plotting the set of compressive strain and mesh resolution at the point where the energy release is zero. In addition, the present evaluation method of the surface tension using the energy release and surface area change for an elastomer with a traction-free surface yields a good prediction for the creasing onset delayed by surface tension without additional numerical implementations or adjustment parameters. This facilitates the comprehensive study of the creasing onset delayed by the surface tension under general loading conditions. The results reveal that tensile deformation in the out-of-plane direction encourages the retardation of the creasing onset via the extension of the width and the energy emission. We further demonstrate that energetically preferential crease interval can be used to evaluate the spacing between creases delayed by moderate surface tension.

我们从计算和物理角度研究了弹性体在三种加载条件下出现折痕的情况。我们进行了二维有限元分析，包括基于扰动力的方法，以检测折痕形成完成后的稳定折痕状态。对折痕状态下的能量释放和折痕深度进行的网格收敛研究为预测折痕发生所需的有限元网格提供了指导。我们还通过绘制能量释放为零时的压缩应变集和网格分辨率图，直观显示了临界起皱点的网格收敛情况。此外，对于无牵引力表面的弹性体，本评估方法利用能量释放和表面积变化来评估表面张力，无需额外的数值实现或调整参数，就能很好地预测因表面张力而延迟的起皱。这有助于在一般加载条件下对表面张力延迟起皱进行全面研究。研究结果表明，平面外方向的拉伸变形会通过扩展宽度和能量释放来促进起皱延迟。我们进一步证明，能量优先折痕间隔可用于评估由适度表面张力延迟的折痕间距。

Journal of the Mechanics and Physics of Solids

A unified disconnection model of stress-driven grain boundary migration in nanocrystalline metals

Anping Hua, Junhua Zhao

doi:10.1016/j.jmps.2023.105515

纳米晶金属中应力驱动晶界迁移的统一断开模型

Disconnection-based model has recently become one of the most recognized ways to unify grain boundary-dominated plasticity of nanocrystalline metals. Here, we proposed a unified disconnection model with a general energetic description formula by considering diverse Burgers vectors, anisotropy in kinetics, shear strengths, and grain size effects in disconnection-mediated grain boundary migration. The quantitative relation was identified between the energy variations from this model and the multi-disconnection slip characteristics of recent in situ atomistic observation. We used the double-disconnection model degraded by this model to reveal the origin of these disconnections nucleating successively from the same free surface and the reason for their composition or decomposition. The obtained energy maps further demonstrated all possible disconnection nucleation, propagation, interaction and annihilation, where the most energetically preferred evolution path of disconnection motion was confirmed by present molecular dynamics simulations. This unified model and its applications enrich our understanding of grain boundary-mediated plasticity and favor the manageable design of nanocrystalline metals.

基于断裂的模型最近已成为统一纳米晶金属晶界主导塑性的公认方法之一。在此，我们提出了一个统一的断开模型，该模型具有通用的能量描述公式，考虑了断开介导的晶界迁移中的各种布尔矢量、动力学各向异性、剪切强度和晶粒尺寸效应。我们确定了该模型的能量变化与最近原位原子观测的多断开滑移特征之间的定量关系。我们使用由该模型退化的双断开模型来揭示从同一自由表面相继成核的这些断开的起源及其组成或分解的原因。所获得的能量图进一步证明了所有可能的断开成核、传播、相互作用和湮灭，其中能量最优先的断开运动演化路径得到了目前分子动力学模拟的证实。这一统一模型及其应用丰富了我们对晶界介导的塑性的理解，有利于纳米晶金属的可控设计。

Mechanics of Materials

A simple stress field solution for conical indentation

Zhi-Qiang Wang, Huai-Rong Xiao, Li-Xun Cai, Mao-Bo Huang

doi:10.1016/j.mechmat.2023.104880

锥形压痕的简单应力场解决方案

Classical contact mechanics has revealed the theoretical conical indentation solution of a stress field for ideal elastic–plastic materials based on the expansion cavity model and elastoplastic theory. This study proposes an equivalent stress analytical equation for the representative volume element of the median energy density point under conical indentation. For materials whose constitutive relations conform to power-law hardening, the equivalent stress solution is defined as the characteristic stress factor, and a simple stress field solution characterized by the logarithmic distribution law of dimensionless stress for conical indentation is presented. The verification results of finite element analysis showed that the proposed solution can uniformly describe the distribution of equivalent stress and three principal stresses in the material deformation region near the cone tip.

经典接触力学基于膨胀腔模型和弹塑性理论揭示了理想弹塑性材料应力场的锥形压痕理论解。本研究提出了锥形压痕下中值能量密度点代表体积元素的等效应力解析方程。对于构成关系符合幂律硬化的材料，等效应力解定义为特征应力系数，并提出了以锥形压痕无量纲应力对数分布规律为特征的简单应力场解。有限元分析的验证结果表明，所提出的解决方案可以均匀地描述锥尖附近材料变形区域的等效应力和三个主应力的分布。

Thin-Walled Structures

Quantifying Variation in Maximum Floor Accelerations of Modular Buildings under Earthquakes through Stochastic Nonlinear Structural Analysis

Chen Wang, Tak-Ming Chan

doi:10.1016/j.tws.2023.111454

通过随机非线性结构分析量化地震下模块化建筑最大楼层加速度的变化

For earthquake-resistant design of modular buildings, reinforced concrete (RC) cores can be a viable choice as the vertical seismic force resisting system. The maximum floor acceleration determines the maximum inertial force that will be transferred by the connections in the horizontal diaphragm to the RC walls. However, the randomness in the structural properties of RC walls may result in fluctuations in the floor acceleration response. Given the limited number of horizontal inter-module connections in modular buildings, the failure of these connections can have severe consequences. To ensure adequate safety margins in the design of horizontal diaphragm connections, it is essential to account for the variations in maximum floor accelerations. To quantify these variations, a 9-story prototype building with RC walls was examined in this study. Monte Carlo simulations were conducted on sample structures with univariate and bivariate randomness in fc (concrete cylinder compressive strength) and Fy (yield strength of steel rebars) of RC walls. Nonlinear response history analyses were performed for each sample structure using 22 ground motions to account for uncertainty in earthquake excitation. The results demonstrated significant and highly complex variations in the maximum floor accelerations due to the randomness considered. A coefficient of variation (CoV) of 0.13 was determined for the maximum floor acceleration response resulting from the bivariate randomness in fc and Fy. Furthermore, the variations were found to increase as the correlation scale in the spatial variation of fc increased. Based on the findings, it is proposed to apply an increase ratio of 1.2 to the maximum floor acceleration to account for the randomness of RC wall properties to ensure adequate safety margins in the design of horizontal diaphragm connections.

在模块化建筑的抗震设计中，钢筋混凝土（RC）核心筒可作为垂直抗震系统的可行选择。最大楼层加速度决定了由水平隔墙连接传递到 RC 墙体的最大惯性力。然而，RC 墙结构特性的随机性可能会导致楼层加速度响应的波动。鉴于模块化建筑中模块间水平连接的数量有限，这些连接的失效可能会造成严重后果。为确保水平隔墙连接设计有足够的安全系数，必须考虑最大楼层加速度的变化。为了量化这些变化，本研究对一栋带有 RC 墙的 9 层原型建筑进行了研究。对样本结构进行了蒙特卡罗模拟，并对 RC 墙的 fc（混凝土圆柱体抗压强度）和 Fy（钢筋屈服强度）进行了单变量和双变量随机分析。使用 22 种地面运动对每个样本结构进行了非线性响应历史分析，以考虑地震激励的不确定性。结果表明，由于考虑了随机性，最大楼层加速度的变化非常明显且非常复杂。由于 fc 和 Fy 的双变量随机性，最大楼层加速度响应的变异系数 (CoV) 为 0.13。此外，随着 fc 空间变化相关尺度的增大，变异系数也随之增大。根据研究结果，建议对最大楼层加速度采用 1.2 的增加比率，以考虑到 RC 墙特性的随机性，从而确保在水平隔墙连接设计中留出足够的安全余量。