【新文速递】2024年3月14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 2 篇，Mechanics of Materials 1 篇，Thin-Walled Structures 2 篇

International Journal of Solids and Structures

A stable numerical framework for long-time dynamic crack analysis

Wenzhen Qu, Yan Gu, Chia-Ming Fan

doi:10.1016/j.ijsolstr.2024.112768

用于长时间动态裂纹分析的稳定数值框架

This paper introduces a stable numerical framework designed to address dynamic crack problems over long-time intervals. The initial step involves the temporal discretization of the governing dynamic equilibrium equations using the arbitrary order Krylov deferred correction method. To ensure precise boundary condition matching, a novel numerical implementation is incorporated into the Krylov deferred correction technique. Subsequently, the resulting system of spatial partial differential equations at each time node is solved using the meshless generalized finite difference method with 4th-order expansions in regions close to the crack-tips and 2nd-order expansions in areas far from the crack-tips. This combined approach capitalizes on the strengths of both the Krylov deferred correction technique and the generalized finite difference method, enabling stable simulations of dynamic cracks with the large time step and without the need for mesh generation. Notably, we refine the collocation nodes near crack tips to attain accurate numerical results for displacement and stress field. Several numerical experiments involving diverse impact loadings are conducted to validate the developed framework. Furthermore, a comparison is made between the dynamic stress intensity factors obtained using our approach and those from existing methods.

本文介绍了一种稳定的数值框架，旨在解决长时间跨度上的动态裂缝问题。第一步是使用任意阶克雷洛夫延迟修正法对支配动态平衡方程进行时间离散化。为了确保精确的边界条件匹配，在克雷洛夫延迟修正技术中加入了一种新的数值实现方法。随后，利用无网格广义有限差分法对每个时间节点上的空间偏微分方程系进行求解，在靠近裂缝尖端的区域采用四阶展开法，在远离裂缝尖端的区域采用二阶展开法。这种组合方法充分利用了克雷洛夫延迟校正技术和广义有限差分法的优点，能够在大时间步长下稳定模拟动态裂缝，且无需生成网格。值得注意的是，我们改进了裂纹尖端附近的配位节点，以获得位移和应力场的精确数值结果。为了验证所开发的框架，我们进行了多次涉及不同冲击载荷的数值实验。此外，我们还比较了使用我们的方法和现有方法获得的动态应力强度因子。

Shape morphing of 2D lattice structures from localized contra-rotations

Kenichiro Yokota, Francois Barthelat

doi:10.1016/j.ijsolstr.2024.112771

从局部反旋转看二维晶格结构的形状变形

The morphing of structure and materials from localized, self-equilibrated actuation loads is limited by Saint-Venant’s principle: Deformations typically decay rapidly from the actuation region, so that changes in shape for the entire structure are negligible. Materials and structures with unusual combinations of elastic properties may induce competitions between different deformation modes over longer decay distances, thereby overcoming this limitation. Here we push this principle to the extreme to generate shape morphing in large 2D lattice structures. We consider planar triangular lattice made of “meta-elements” with unusual combinations of axial, shear and flexural stiffness. We show, using finite element models, that localized contra-rotations on the center nodes can morph the entire structure in bending, provided that adequate combinations of elastic properties are selected. We use the global curvature as measure of this deformation to establish precise design guidelines for morphing. We finally propose physical embodiments of these meta-elements and lattice structures which we fabricated using laser cutting, and which tested using servo-motors to impose contra-rotations on the two center nodes. The results validate our models and the design guidelines: planar lattice can morph in bending with significant curvatures, especially when the size of the structure is small. In comparison, similar lattice structures made of regular beams show no morphing, with all the deformation localized near the center nodes. These findings may lead to new strategies to actuate morphing materials and structures, with applications in aerospace or robotics.

结构和材料在局部自平衡致动载荷作用下的变形受到圣-韦南原理的限制：变形通常会从致动区域迅速衰减，因此整个结构的形状变化可以忽略不计。具有不同寻常弹性特性组合的材料和结构可能会在较长的衰减距离内引起不同变形模式之间的竞争，从而克服这一限制。在这里，我们将这一原理发挥到极致，在大型二维晶格结构中产生形状变形。我们考虑的是由 "元元元 "组成的平面三角形晶格，其轴向、剪切和挠曲刚度具有不同寻常的组合。我们利用有限元模型证明，只要选择适当的弹性特性组合，中心节点上的局部反旋转就能使整个结构在弯曲时变形。我们使用全局曲率来衡量这种变形，从而为变形制定精确的设计准则。最后，我们提出了这些元元件和晶格结构的物理实施方案，我们使用激光切割技术制造了这些元元件和晶格结构，并使用伺服电机对两个中心节点施加反向旋转进行了测试。测试结果验证了我们的模型和设计准则：平面晶格在弯曲时可以产生明显的曲率变形，尤其是在结构尺寸较小时。相比之下，由规则梁构成的类似晶格结构不会发生变形，所有变形都集中在中心节点附近。这些发现可能会带来驱动变形材料和结构的新策略，并应用于航空航天或机器人领域。

Mechanics of Materials

Shear bands occurrence in collapsing thick-walled cylinders: Role of user-defined perturbations

M. Xavier, M. Reynaud

doi:10.1016/j.mechmat.2024.104960

厚壁圆柱体坍塌时产生的剪切带：用户定义的扰动的作用

Self-organization of multiple adiabatic shear bands (ASB) is often investigated through collapsing thick-walled cylinders (TWC). In the present work, the material behaviour is described by a thermoviscoplastic constitutive law with a strain energy based failure model. Inhomogeneities in the specimen are somehow represented using Voronoi cells. In addition, a user-defined perturbation is imposed in the numerical perturbation to each Voronoi cell. Therefore, a mesh independent perturbation is obtained. Several draws of initial perturbation are considered to investigate variability in shear band patterns. The numerous realizations are analyzed through an algorithm to track and count shears bands providing statistically significant results. The influence of the failure model and perturbation parameters on shear bands number and length is studied. While short bands are affected by the size of the cells, it is shown that the self-organized pattern of developed bands is relatively independent of the imposed Voronoïcell structure. The amplitude of the perturbation affects neither the pattern nor the length of bands (within the considered range of amplitude of the user-defined perturbation).

多绝热剪切带（ASB）的自组织通常通过厚壁圆柱体（TWC）的坍塌进行研究。在本研究中，材料行为由热粘塑性构成定律和基于应变能的失效模型来描述。试样中的非均质性以某种方式用 Voronoi 单元表示。此外，在对每个 Voronoi 单元进行数值扰动时，会施加用户定义的扰动。因此，可以获得与网格无关的扰动。为了研究剪切带模式的变化，考虑了几种初始扰动。通过跟踪和统计剪切带的算法分析了大量的实现情况，并得出了具有统计意义的结果。研究了破坏模型和扰动参数对剪切带数量和长度的影响。虽然短剪切带会受到单元尺寸的影响，但研究表明，已形成剪切带的自组织模式相对独立于所施加的 Voronoïcell 结构。扰动的振幅既不会影响剪切带的形态，也不会影响剪切带的长度（在用户定义的扰动振幅范围内）。

Thin-Walled Structures

Experimental and Numerical Investigation of Square Concrete-Filled Double-Skin Steel Stiffened Tubular Stub Columns with CHS Inner Tubes under Axial Compression

Wei-Feng Huang, Yong-Bo Shao, M.F. Hassanein, Marijana Hadzima-Nyarko, Dorin Radu, K.A. Cashell

doi:10.1016/j.tws.2024.111792

带 CHS 内管的方形混凝土填充双层钢加劲管式支柱在轴向压缩下的实验和数值研究

This paper explores the performance of concrete-filled double-skin (square stiffened hollow sections (SHS) outer and circular hollow sections (CHS) inner) steel tubular (CFDSST) stub columns under axial compression through experimental research and finite element analysis. The static axial compression experiments of six concrete-filled stiffened steel tubular (CFST) stub columns and fifteen CFDSST stub columns were conducted. The test method, process, phenomena and results are introduced in detail. The results indicated that compared with conventional CFST stub columns, CFDSST stub columns with reasonable hollow ratio can maintain load-carrying capacity, increase ductility and reduce self-weight. Increasing the strength of concrete is the most effective way to increase the load-carrying capacities of specimens when other variables remain constant. Finite element (FE) software was then utilised to generate the models of current specimens. The simulation results showed reasonableness and accuracy compared to the experimental results. Based on the validated models, parameter analysis was performed to reveal the influence of concrete strength, width-to-thickness ratio of the outer steel tube, stiffener depth, hollow ratio and yield strength of the outer steel tube on the ultimate strengths of the specimens. In addition, compared with test and FE strengths, the ultimate strengths predicted by available international codes were found to be quite conservative. Consequently, a formula was proposed to predict the load-carrying capacity of CFDSST stub columns considering the effective cross-sectional areas of the outer steel tubes and the strength of the confined concrete. The formula has been shown to provide the best prediction with acceptable reliability.

本文通过实验研究和有限元分析，探讨了混凝土填充双层（外层为方形加劲空心截面（SHS），内层为圆形空心截面（CHS））钢管桩柱（CFDSST）在轴向压缩下的性能。对六根混凝土填充加劲钢管（CFST）短柱和十五根 CFDSST 短柱进行了静态轴向压缩实验。详细介绍了试验方法、过程、现象和结果。结果表明，与传统 CFST 存根柱相比，合理空心率的 CFDSST 存根柱可保持承载能力、增加延性并减轻自重。在其他变量不变的情况下，提高混凝土强度是提高试件承载能力的最有效方法。然后利用有限元（FE）软件生成当前试样的模型。与实验结果相比，模拟结果显示出合理性和准确性。在验证模型的基础上，进行了参数分析，以揭示混凝土强度、外钢管宽厚比、加劲件深度、空心率和外钢管屈服强度对试件极限强度的影响。此外，与试验和 FE 强度相比，发现现有国际规范预测的极限强度相当保守。因此，考虑到外钢管的有效截面积和受限混凝土的强度，提出了一个公式来预测 CFDSST 存根柱的承载能力。结果表明，该公式可提供最佳预测，且可靠性可接受。

On the collapse stress of tubular enhanced anti-tetra-missing rib structure

Chuanbiao Zhang, Fucong Lu, Tinghui Wei, Xiangyu Ling, Beicheng Lin, Yilin Zhu

doi:10.1016/j.tws.2024.111801

论管状增强型抗四漏筋结构的坍塌应力

In the contemporary landscape of engineering, escalating demands for advanced material and structural performance have brought metamaterials to the forefront. Among them, the enhanced anti-tetra-missing rib structure has gained prominence owing to its auxetic behavior under significant strain. However, the lack of research on its quasi-static and dynamic mechanical performance have hindered its practical application. To address this, we introduce the tubular enhanced anti-tetra-missing rib structure (TEATMRS) and derive its collapse stress expression under various conditions. Through extensive simulations and experiments, we explore its deformation mechanisms and assess the influence of the structural geometric parameters and impact velocity on collapse stress. The results demonstrate excellent agreement among theoretical description, numerical analysis, and experimental tests, establishing the feasibility of the proposed collapse stress expression. These findings provide a theoretical foundation and design guidance for TEATMRS in engineering applications.

在当代工程领域，人们对先进材料和结构性能的要求不断提高，超材料也随之进入人们的视野。其中，增强型抗四漏肋结构因其在巨大应变下的辅助行为而备受瞩目。然而，由于缺乏对其准静态和动态机械性能的研究，阻碍了其实际应用。针对这一问题，我们引入了管状增强型抗四漏肋结构（TEATMRS），并推导出其在各种条件下的塌陷应力表达式。通过大量的模拟和实验，我们探索了其变形机制，并评估了结构几何参数和冲击速度对坍塌应力的影响。结果表明，理论描述、数值分析和实验测试之间存在极好的一致性，从而确定了所提出的坍塌应力表达式的可行性。这些发现为 TEATMRS 的工程应用提供了理论基础和设计指导。

来源：复合材料力学仿真Composites FEM

【新文速递】2024年1月3日固体力学SCI期刊最新文章

今日更新：Thin-Walled Structures 2 篇Thin-Walled StructuresDynamic response and cumulative damage mechanism of simplified hull girders under repeated underwater explosionsXiangyu Li, Minzu Liang, Zhandong Tian, Meng Zhoudoi:10.1016/j.tws.2023.111554水下重复爆炸下简化船体大梁的动态响应和累积损伤机制The dynamic response and cumulative damage mechanism of simplified hull girders (SHGs) subjected to repeated underwater explosions were investigated in this research. Experimental and numerical investigations were conducted to gain a comprehensive understanding of the relationship between cumulative damage and explosive charge. Three series of experiments were carried out on SHGs, subjecting them to both single and repeated loading (up to five times). The analysis focused on the overall deflection values of the SHG and the local bottom plate deflection values, revealing a linear relationship with the cumulative number of occurrences. A validated finite element simulation model was employed to examine the response of the SHGs under repeated blast loading, utilizing experimental results for validation. An impact factor was established to quantify the magnitude of the explosive force, considering both the power of the explosive and the distance of detonation. The SHGs showed localized deformation at 10 impact factors, but experience pronounced cumulative effects at 14.4 and 20 impact factors. Furthermore, a consistent decline in the residual strength of the SHGs as the number of explosions increased. Following the first underwater explosion, the damaged SHG displayed an ultimate plastic bending moment of 3696.5 N∙M, reflecting a 16.3% reduction compared to the unloaded SHGs. This reduction can primarily be attributed to the altered load distribution on the deformed SHGs. These findings contributed to the understanding of the cumulative damage behavior and response of SHGs exposed to repeated underwater explosions, providing valuable insights for the design and structural integrity assessment of naval vessels.本研究探讨了简体船体大梁（SHGs）在反复水下爆炸下的动态响应和累积损伤机制。为了全面了解累积损伤与爆炸装药之间的关系，进行了实验和数值研究。对 SHG 进行了三个系列的实验，使其承受单次加载和重复加载（最多五次）。分析的重点是 SHG 的整体挠度值和局部底板挠度值，结果表明两者之间存在线性关系。采用经过验证的有限元仿真模型来研究 SHG 在重复爆炸加载下的响应，并利用实验结果进行验证。考虑到炸药的威力和爆炸距离，建立了一个冲击系数来量化爆炸力的大小。SHG 在冲击系数为 10 时出现局部变形，但在冲击系数为 14.4 和 20 时出现明显的累积效应。此外，随着爆炸次数的增加，SHG 的残余强度持续下降。第一次水下爆炸后，受损的 SHG 显示出 3696.5 N∙M 的极限塑性弯曲力矩，与未加载的 SHG 相比降低了 16.3%。这种降低主要归因于变形的 SHG 上负载分布的改变。这些研究结果有助于了解 SHGs 在反复水下爆炸中的累积损伤行为和响应，为舰船的设计和结构完整性评估提供了有价值的见解。Prestress analysis and geometry optimization for conical cable domes with zero Gaussian curvatureYutao He, Jiamin Guo, Yu Zhao, Mingliang Zhu, Zhiyu Jiangdoi:10.1016/j.tws.2023.111555零高斯曲率锥形索穹的预应力分析和几何优化The conical cable dome with a rotating cone and zero Gaussian curvature is a new type of cable dome with the generatrix that follows a straight line. The paper studies the prestress design and mechanical properties of such cable domes. First, on the basis of the section and vertical diagrams of the proposed cone, a simplified method is developed to calculate feasible prestresses of cables and struts using the principle of nodal balance. Second, prestress distribution, load-bearing capacity, and prestress of the conical cable domes with 15 different combinations of rise-span ratio and inner triangular slope under both prestress and load states are studied. Additionally, the paper proposes five load conditions to assess the performance of the conical cable domes. Finally, the total strain energy, basic frequency, radial reaction, and gravity are optimized through single-criterion and multi-criterion based on the combination of a genetic algorithm and the Newton iteration method. To keep the outer appearance of the conical cable dome, the work selects the strut length as the optimization variable. An optimized conical cable dome is recommended with a low prestress uniformity index and high uniformity index. The results indicate that the conical cable dome is sensitive to the asymmetrical loads, especially the wind loads. For the single-criterion optimization, the structure with the basic frequency under loads as the objective function has the best load-bearing capacity. After optimization, the maximum nodal displacement is 32% and 43% of the original one under LC4 and LC5. Besides, to get a synthetic optimization result, a multi-criterion optimization is suggested.具有旋转锥和零高斯曲率的圆锥形缆索穹顶是一种新型缆索穹顶，其生成矩阵沿着一条直线。本文研究了这种索穹的预应力设计和力学性能。首先，在拟建锥体的剖面图和竖向图的基础上，开发了一种简化方法，利用节点平衡原理计算电缆和支柱的可行预应力。其次，研究了 15 种不同升跨比和内三角坡度组合的锥形索穹在预应力和荷载状态下的预应力分布、承载能力和预应力。此外，本文还提出了评估锥形索穹性能的五种荷载条件。最后，基于遗传算法和牛顿迭代法的组合，通过单标准和多标准对总应变能、基频、径向反力和重力进行了优化。为了保持锥形电缆穹顶的外观，作品选择了支柱长度作为优化变量。建议优化后的锥形索顶具有低预应力均匀性指数和高均匀性指数。结果表明，锥形缆索穹顶对不对称荷载，尤其是风荷载非常敏感。在单标准优化中，以荷载作用下的基本频率为目标函数的结构具有最佳承载能力。优化后，在 LC4 和 LC5 条件下，最大节点位移分别为原来的 32% 和 43%。此外，为了获得合成优化结果，建议采用多准则优化。来源：复合材料力学仿真Composites FEM