【新文速递】2024年8月24日固体力学SCI期刊最新文章

 

今日更新：International Journal of Solids and Structures 5 篇，Journal of the Mechanics and Physics of Solids 1 篇，Mechanics of Materials 5 篇，Thin-Walled Structures 8 篇

International Journal of Solids and Structures

New numerical resolution of the elastic quarter-space, eighth-space and finite-length-space contact problems

Amakoe Komlavi Ahyee, Daniel Nelias, Thibaut Chaise, Arnaud Duval

doi:10.1016/j.ijsolstr.2024.113031

弹性四分之一空间、八空间和有限长空间接触问题的新数值解

In this paper, a new algorithm to solve the elastic quarter-space, the eighth-space and the finite-length-space contact problems is proposed. This corresponds to an extension of the Hertz theory. The theoretical foundations of such a problem are limited, due to the presence of displacements at the free edges - or stresses at the virtual edges - resulting to complex boundary conditions. The new approach presented here is 3D and based on Guibault’s ingenious fast correction method. In this approach, the edge effects are taken into account by introducing two corrective factors ψ1, ψ2 respectively on the (Ox) and (Oz) axes to replace the mirror pressure iterative process of Hetenyi. The exact numerical values of these two correction factors are derived analytically. The results show that the free edge can substantially increase locally the contact pressure and therefore the stresses and displacement fields if close to the contact area. So the pressure field and the contact zone present an asymmetry which is more pronounced as the free edge is getting closer. This study is carried out on spaces with one, two and four free edges which will be respectively called: quarter-space, eighth-space and finite-length-space. A validation is performed using a Finite Element Method (FEM) analysis. A parametric study is also performed to exhibit the differences with the Hertz solution, including in the situation where one expects the truncation of the contact area when the free edge is virtually located within the Hertz contact area.

本文提出了一种解决弹性四分之一空间、八分之一空间和有限长度空间接触问题的新算法。这相当于赫兹理论的扩展。由于自由边缘存在位移或虚拟边缘存在应力，导致边界条件复杂，此类问题的理论基础受到限制。本文介绍的新方法是三维方法，基于 Guibault 独创的快速修正方法。在这种方法中，通过在（Ox）轴和（Oz）轴上分别引入两个校正因子ψ1、ψ2，将边缘效应考虑在内，以取代赫特尼的镜面压力迭代过程。这两个校正因子的精确数值是通过分析得出的。结果表明，如果自由边缘靠近接触区域，会大大增加局部接触压力，从而增加应力场和位移场。因此，压力场和接触区呈现出不对称的现象，当自由边缘越来越靠近时，这种不对称现象更加明显。这项研究针对的是有一个、两个和四个自由边缘的空间，分别称为四分之一空间、八分之一空间和有限长度空间。使用有限元法（FEM）分析进行验证。还进行了参数研究，以显示与赫兹解法的不同之处，包括当自由边缘实际上位于赫兹接触区域内时，预计接触区域会被截断的情况。

Microscopic instabilities in single crystal matrix composites

Jacob Aboudi, Srihari Dodla, Rivka Gilat

doi:10.1016/j.ijsolstr.2024.113035

单晶基复合材料的微观不稳定性

A finite strain micromechanical analysis is presented for the prediction of the loss of microscopic stability of a class of metal matrix composites that are subjected to axial compressive loading and undergoing large deformations. The metallic constituent behavior is modeled by the single crystal anisotropic plasticity theory in which, due to the resolved shear stresses, plastic deformations occur along certain pre-defined slip planes. Thus, this incremental plasticity theory is capable of providing the effect of the applied axial loading on the induced shear stresses which dominate the microbuckling. The composites are assumed to possess slight imperfections at the interfaces, and in order to satisfy the interfacial conditions, a perturbation expansion is employed which yields zero and first order micromechanical analysis problems. The zero order problem corresponds to the micromechanical modeling of the composite with no imperfections, whereas the solution of the first order problem is utilized to obtain the critical stresses and deformations at which bifurcation buckling occurs. Both problems are solved by employing the finite strain high-fidelity generalized method of cells (HFGMC) micromechanics. Applications are given for various types of single crystal matrix composites including layered, particulate, continuous and short fiber composites. Finally, a comparison between the compressive strengths of a standard metal matrix boron/aluminum and SiC/single crystal composites is presented and discussed.

为预测一类金属基复合材料在轴向压缩载荷和大变形作用下的微观稳定性损失，提出了一种有限应变细观力学分析方法。单晶各向异性塑性理论模拟了金属组分的行为，在单晶各向异性塑性理论中，由于分解的剪切应力，塑性变形沿着预定的滑移面发生。因此，这种增量塑性理论能够提供施加轴向载荷对主导微屈曲的诱导剪应力的影响。假设复合材料在界面处具有轻微缺陷，为了满足界面条件，采用微扰展开，得到零阶和一阶微力学分析问题。零阶问题对应于无缺陷复合材料的微观力学建模，而一阶问题的解用于获得发生分岔屈曲的临界应力和变形。采用有限应变高保真广义元胞细观力学方法解决了这两个问题。应用于各种类型的单晶基复合材料，包括层状，颗粒状，连续和短纤维复合材料。最后，对标准金属基硼/铝复合材料和SiC/单晶复合材料的抗压强度进行了比较。

On the dynamic shear failure of Ti-6Al-4V in different test specimen geometries

Yutian Du, Zejian Xu, Caifang Qin, Mengyu Su, P.J. Tan, Fenglei Huang

doi:10.1016/j.ijsolstr.2024.113036

Ti-6Al-4V在不同试样几何形状下的动态剪切破坏

In this paper, the dynamic shear response and failure of Ti-6Al-4V using four different test specimen geometries, viz. Hat-Shaped Specimen (HSS), Flat Hat-Shaped Specimen (FHSS), Chip Hat-Shaped Specimen (CHSS) and Double Shear Specimen (DSS), are critically examined and compared. Through a combination of experiments (using the standard Split-Hopkinson Pressure Bar system), finite-element simulations and metallographic examinations of their fracture morphology, the dynamic shear characteristics (strain hardening, strain rate strengthening effect and failure strain) of Ti-6Al-4V obtained using the different specimen geometries are critically examined, compared and analyzed. It will be shown that differences in the stress/strain uniformity, the plastic deformation zone, and the stress state induced by the different specimen geometries lead to discrepancies in the measured shear response and failure that were observed. The shear stress–strain curve obtained using the DSS will be shown to be more precise than the other specimen geometries.

本文采用帽形试样(HSS)、扁平帽形试样(FHSS)、片状帽形试样(CHSS)和双剪切试样(DSS)四种不同的试样几何形状，对Ti-6Al-4V的动态剪切响应和破坏进行了严格的检验和比较。通过实验(使用标准的Split-Hopkinson压杆系统)、有限元模拟和断口形貌的金相检验相结合，对不同试样几何形状下获得的Ti-6Al-4V的动态剪切特性(应变硬化、应变速率强化效应和失效应变)进行了严格的检验、比较和分析。结果表明，应力/应变均匀性、塑性变形区和不同试样几何形状引起的应力状态的差异导致了所测剪切响应和所观察到的破坏的差异。使用DSS获得的剪切应力-应变曲线将显示比其他试样几何形状更精确。

Theoretical and numerical analysis on buckling instability in a thin film sandwiched between two finite-thickness substrates under in-plane compression

Xuebo Yuan, Peizhi Zhao, Qiuqiu Fan, Youshan Wang, Xiangyu Li

doi:10.1016/j.ijsolstr.2024.113037

夹在两个有限厚度衬底之间的薄膜在平面内压缩下屈曲失稳的理论和数值分析

Capturing the buckling instability mechanics of multi-layered film/substrate structures is essential for providing theoretical guidelines for designing flexible electronics (e.g., stretchable interconnects and strain-limiting structures) and understanding the morphogenesis in biology and geology. Previous buckling models of tri-layer substrate/film/substrate structures often assume infinite substrate thickness and incomplete forms of interfacial shear stress, failing to distinguish between local wrinkling and global buckling. In this work, we extend our previous model (Yuan et al., 2023) by accounting for both finite substrate thickness and a complete form of interfacial shear stress, without assuming uniform membrane strain in the film, to study the buckling instability of tri-layer structures. The local wrinkling versus global buckling is distinguished through energy analysis, yielding phase diagrams for a wide range of geometric parameters and material properties. The effects of finite substrate thickness and moduli on the critical compressive strain and wavelength for the onset of local wrinkling are thoroughly investigated. The high accuracy of current model is demonstrated by the excellent agreement between analytical predictions and finite element analysis. This study provides new insights into the stability analysis of substrate/film/substrate systems, and will aid in the design of flexible electronics

捕获多层薄膜/衬底结构的屈曲不稳定性机制对于为设计柔性电子器件(例如，可拉伸互连和应变限制结构)以及理解生物学和地质学中的形态发生提供理论指导至关重要。以往的三层衬底/薄膜/衬底结构屈曲模型通常假设衬底厚度无限，界面剪切应力形式不完整，无法区分局部起皱和整体屈曲。在这项工作中，我们扩展了之前的模型(Yuan et al.， 2023)，考虑了有限的衬底厚度和完整形式的界面剪切应力，而没有假设薄膜中的均匀膜应变，以研究三层结构的屈曲不稳定性。通过能量分析来区分局部起皱和整体屈曲，得出了广泛几何参数和材料性能的相图。研究了有限衬底厚度和模量对发生局部起皱的临界压缩应变和波长的影响。分析预测结果与有限元分析结果吻合较好，证明了现有模型具有较高的精度。该研究为衬底/薄膜/衬底系统的稳定性分析提供了新的见解，并将有助于柔性电子产品的设计

Multiscale modeling of diffuse damage and localized cracking in quasi-brittle materials under compression with a quadratic friction law

Lun-Yang Zhao, Lu Ren, Ling-Hui Liu, Yuan-Ming Lai, Fu-Jun Niu, Tao You

doi:10.1016/j.ijsolstr.2024.113038

基于二次摩擦规律的准脆性材料压缩扩散损伤和局部裂纹多尺度模拟

The diffuse damage and localized cracking of quasi-brittle materials (i.e., rocks and concrete) under compression can be delineated by a matrix-microcrack system, wherein a solid matrix phase is weakened by a large number of randomly oriented and distributed microcracks, and the macroscopic cracking is formed by a progressive evolution of microcracks. Several homogenization-based multiscale models have been proposed to describe this matrix-microcrack system, but most of them are based on a linear friction law on the microcrack surface, rendering a linear strength criterion. In this paper, we propose a new quadratic friction law within the local multiscale friction-damage (LMFD) model to capture the plastic distortion due to frictional sliding along the rough microcrack surface. Following that, a macroscopic Ottosen-type nonlinear strength criterion is rationally derived with up-scaling friction-damage coupling analysis. An enhanced semi-implicit return mapping (ESRM) algorithm with a substepping scheme is then developed to integrate the complex nonlinear constitutive model. The performance of LMFD model is evaluated compared to a wide range of experimental data on plain concretes, and the robustness of ESRM algorithm is assessed through a series of numerical tests. Subsequently, to effectively describe the localized cracking process, a regularization scheme is proposed by combining the phase-field model with the established LMFD model, and the discretization independent crack localization is numerically verified.

准脆性材料(即岩石和混凝土)在压缩作用下的弥漫性损伤和局部开裂可以用基体-微裂纹系统来描述，其中固体基体相被大量随机取向和分布的微裂纹削弱，宏观开裂是由微裂纹的逐步演化形成的。目前已经提出了几种基于均质化的多尺度模型来描述这种基体-微裂纹系统，但大多数模型都是基于微裂纹表面的线性摩擦规律，给出了线性强度准则。本文在局部多尺度摩擦损伤(LMFD)模型中提出了一种新的二次摩擦规律，以捕捉粗糙微裂纹表面摩擦滑动引起的塑性变形。在此基础上，通过上尺度摩擦损伤耦合分析，合理推导了宏观ottosen型非线性强度准则。针对复杂非线性本构模型，提出了一种改进的半隐式回归映射(ESRM)算法。将LMFD模型的性能与素面混凝土的大量实验数据进行比较，并通过一系列数值试验对ESRM算法的鲁棒性进行了评估。随后，为了有效地描述局部裂纹过程，提出了相场模型与LMFD模型相结合的正则化方案，并对离散化独立裂纹局部化进行了数值验证。

Journal of the Mechanics and Physics of Solids

Derivation of an effective plate theory for parallelogram origami from bar and hinge elasticity

Hu Xu, Ian Tobasco, Paul Plucinsky

doi:10.1016/j.jmps.2024.105832

从杆弹性和铰弹性出发推导平行四边形折纸的有效板理论

Periodic origami patterns made with repeating unit cells of creases and panels bend and twist in complex ways. In principle, such soft modes of deformation admit a simplified asymptotic description in the limit of a large number of cells. Starting from a bar and hinge model for the elastic energy of a generic four parallelogram panel origami pattern, we derive a complete set of geometric compatibility conditions identifying the pattern’s soft modes in this limit. The compatibility equations form a system of partial differential equations constraining the actuation of the origami’s creases (a scalar angle field) and the relative rotations of its unit cells (a pair of skew tensor fields). We show that every solution of the compatibility equations is the limit of a sequence of soft modes — origami deformations with finite bending energy and negligible stretching. Using these sequences, we derive a plate-like theory for parallelogram origami patterns with an explicit coarse-grained quadratic energy depending on the gradient of the crease-actuation and the relative rotations of the cells. Finally, we illustrate our theory in the context of two well-known origami designs: the Miura and Eggbox patterns. Though these patterns are distinguished in their anticlastic and synclastic bending responses, they show a universal twisting response. General soft modes captured by our theory involve a rich nonlinear interplay between actuation, bending and twisting, determined by the underlying crease geometry.

由折痕和面板的重复单元格组成的周期性折纸图案以复杂的方式弯曲和扭曲。原则上，这种软变形模态允许在大量单元的极限下进行简化的渐近描述。从广义四平行四边形折纸板弹性能的杆铰模型出发，推导出一套完整的几何相容条件，确定了该极限下折纸板的软模态。相容性方程形成了一个偏微分方程组，约束折纸折痕的驱动(标量角场)和单位细胞的相对旋转(一对斜张量场)。我们证明了相容方程的每一个解都是一系列软模态的极限——具有有限弯曲能量和可忽略拉伸的折纸变形。利用这些序列，我们导出了平行四边形折纸图案的类板理论，该理论具有显式的粗粒度二次能量，这取决于折痕驱动的梯度和细胞的相对旋转。最后，我们以两种著名的折纸设计:Miura和Eggbox模式来说明我们的理论。虽然这些模式在抗裂和同裂弯曲响应中有所区别，但它们表现出普遍的扭转响应。我们的理论捕获的一般软模式涉及驱动，弯曲和扭转之间丰富的非线性相互作用，由底层折痕几何决定。

Mechanics of Materials

Revisiting Andrews method and grain boundary resistivity from a computational multiscale perspective

D. Güzel, T. Kaiser, H. Bishara, G. Dehm, A. Menzel

doi:10.1016/j.mechmat.2024.105115

从计算多尺度角度重述Andrews方法和晶界电阻率

The effective material response as observed at a macro level is a manifestation of the material microstructure and lower scale processes. Due to their distinct atomic arrangement, compared to bulk material, grain boundaries significantly affect the electrical properties of metals. However, a scale-bridging understanding of the associated microstructure–property relation remains elusive so that phenomenological approaches such as the Andrews method are typically applied. In the present contribution we revisit Andrews method from a computational multiscale perspective to analyse its limits and drive concepts to go beyond. By making use of homogenisation techniques we provide a solid theoretical foundation to the Andrews method, discuss its applicability and tacit assumptions involved, and resolve its core limitations. To this end, simplistic analytical examples are discussed in a one-dimensional setting to show the fundamental relation between the Andrews method and homogenisation approaches. Building on this knowledge the importance of the underlying microscale morphology and associated morphology-induced anisotropies are in the focus of investigations based on simplified microstructures. Concluding the analysis, scaling laws for isotropic microstructures are derived and the transferability of the results to realistic, (quasi-)isotropic polycrystals is shown.

在宏观水平上观察到的有效材料响应是材料微观结构和低尺度过程的表现。由于其独特的原子排列，与块状材料相比，晶界显著影响金属的电学性能。然而，对相关微观结构-性质关系的尺度桥接理解仍然难以捉摸，因此通常应用诸如安德鲁斯方法之类的现象学方法。在目前的贡献中，我们从计算多尺度的角度重新审视安德鲁斯方法，分析其局限性并推动概念超越。通过使用均质化技术，我们为安德鲁斯方法提供了坚实的理论基础，讨论了其适用性和所涉及的隐性假设，并解决了其核心局限性。为此，在一维环境中讨论了简单的分析例子，以显示安德鲁斯方法和均质化方法之间的基本关系。基于这一知识，基于简化微结构的研究重点是潜在的微尺度形态和相关的形态诱导的各向异性。通过分析，导出了各向同性微观结构的标度规律，并证明了结果可转移到实际的(准)各向同性多晶体。

Feasibility problems with the differential Mori-Tanaka method and modifications for refining inclusion stress predictions

Deepjyoti Dhar, Atul Jain

doi:10.1016/j.mechmat.2024.105125

微分Mori-Tanaka方法的可行性问题和改进，以改进包体应力预测

Prevalent mean-field homogenization techniques excel in approximating effective stiffness, they fall short in predicting the stress states of individual inclusions within the same phase. Differential Mori-Tanaka (DMT) method presents possibilities for estimating stresses/strains in individual inclusions, which can be used for improved micromechanics of short fibre composites. This paper showcases inherent physical admissibility problems associated with DMT and proposes a novel modification to address them. The two schemes viz. DMT and modified-DMT are benchmarked using full-FE results. The modified-DMT effectively circumvents the physical admissibility problems with the DMT and is shown to results in qualitatively superior predictions of stresses in individual inclusions.

普遍的平均场均匀化技术在近似有效刚度方面表现出色，但在预测同一相内单个夹杂的应力状态方面存在不足。差分Mori-Tanaka (DMT)方法提供了估计单个夹杂物的应力/应变的可能性，可用于改进短纤维复合材料的微观力学。本文展示了与DMT相关的固有物理可采性问题，并提出了一种新的修改方法来解决这些问题。两种方案，即DMT和修改DMT是基准使用全有限元结果。改进后的DMT有效地规避了DMT的物理可容许性问题，并显示出对单个包裹体应力的高质量预测。

Semi-Analytical Framework for Modelling of Surface Heating and Its Impact on Nonlinear Stability of Nanotube Reinforced Doubly Curved Porous Fiber Composite Panels

Sumeet Chakraborty, Amit Yadav, Tanish Dey, Rajesh Kumar, Ankur Singh

doi:10.1016/j.mechmat.2024.105126

纳米管增强双弯曲多孔纤维复合材料板表面加热及其对非线性稳定性影响的半解析框架

In elevated temperatures, the stiffness of the panel deteriorates and can lead to loss of stability of structures. Hence, the stability analysis of thin-walled structures is a critical investigation in the thermal environment. Finding such criticality, the present semi-analytical study investigated the nonlinear stability behaviour of porous doubly curved thin-walled panels subject to surface heating like dome heating and localised heating. To improve the stiffness of the panel, the matrix is reinforced with carbon nanotubes (CNTs). Improper mixing of such nanoparticles can lead to agglomeration or bundling effect, which may reduce the structure's stiffness. Still, its investigation in surface heating can be an essential aspect that is found to be untouched by researchers for porous shell panels. The effective material properties of the three-phase composite panel are determined using the Eshelby-Mori-Tanaka (E-M-T) approach and the Chamis homogenization technique. Using the variational principle, governing equations are derived and further simplified to non-linear algebraic equations using the Galerkin technique. Gibson and Ashby foam model is used to model cell structure. It is observed that a complete agglomerated state results in higher post-buckling strength, a continuous deformation path due to biaxial compression and curved geometry, and porosity of cellular structure distribution and cell walls are the important parameters to study the stability of panel in a thermal environment are the major conclusions drawn from the current study. Current investigation can be an important contribution towards modelling aircraft structure in supersonic airflow and furnace walls of thermal power plants subjected to localised heating.

在高温下，面板的刚度会恶化，并可能导致结构稳定性的丧失。因此，薄壁结构的稳定性分析是热环境下的一项重要研究。找到这种临界，本半解析研究探讨了多孔双弯曲薄壁板的非线性稳定性行为在表面加热，如圆顶加热和局部加热。为了提高面板的刚度，采用碳纳米管(CNTs)对基体进行增强。这类纳米颗粒的不当混合会导致团聚或捆绑效应，从而降低结构的刚度。尽管如此，它在表面加热方面的研究可能是多孔壳板研究人员未触及的一个重要方面。采用Eshelby-Mori-Tanaka (E-M-T)法和Chamis均质技术测定了三相复合材料板的有效材料性能。利用变分原理推导了控制方程，并利用伽辽金技术进一步简化为非线性代数方程。采用Gibson和Ashby泡沫模型模拟细胞结构。研究结果表明，完整的团聚状态可以获得较高的屈曲后强度，双轴压缩和弯曲几何形状导致的连续变形路径，以及细胞结构分布和细胞壁的孔隙率是研究板在热环境下稳定性的重要参数。目前的研究可以为超音速气流中的飞机结构和局部加热下火电厂炉壁的建模做出重要贡献。

On the tractive rolling nanocontact of an exponentially graded coating-substrate structure

Youxue Ban, Zhiqiang Li, Changwen Mi

doi:10.1016/j.mechmat.2024.105127

指数梯度涂层-衬底结构的牵引滚动纳米接触

This paper studies the tractive rolling nanocontact occurring between an exponentially graded coating-substrate structure and a circular rigid indenter. Employing the framework of Steigmann–Ogden surface elasticity, it models the surface effects inherent in the nanocontact of graded coatings. The contact area is assumed to comprise a central stick zone bounded by two distinct slip zones. Central to the investigation is the utilization of the nonclassical Flamant solution, which serves as the foundational framework for deriving integral equations governing the continuity of both vertical and tangential displacement gradients. Utilizing Gauss–Chebyshev quadratures, the paper discretizes and collocates these integral equations, along with the force equilibrium conditions and shear traction smooth condition at the leading side stick/slip transition point. An iterative algorithm is then developed to tackle the resultant algebraic system, particularly concerning the discretized contact pressure and friction traction. The paper rigorously validates its proposed solution method and numerical algorithm against existing literature results, showcasing their accuracy and reliability. Moreover, it conducts extensive parametric studies to unravel the effects of various parameters, such as surface material properties, coefficient of friction, inhomogeneity index, and thickness of the exponentially graded coating. These analyses uncover the significant role of surface effects in shaping contact pressure, frictional traction, stresses, subsidence distributions, and stick–slip zones. Notably, the inclusion of surface effects is found to reduce maximum stress and subsidence while inducing a shift of the stick region towards the rolling direction. The parametric exploration of graded coating properties also offers insights into tailoring nanocontact responses for gradient nanostructures.

本文研究了指数梯度涂层-衬底结构与圆形刚性压头之间的牵引滚动纳米接触。采用Steigmann-Ogden表面弹性的框架，它模拟了梯度涂层纳米接触中固有的表面效应。假定接触区域包括一个由两个不同的滑动带包围的中心粘滞区。研究的核心是利用非经典Flamant解，它作为推导控制垂直和切向位移梯度连续性的积分方程的基础框架。利用高斯-切比雪夫正交，对这些积分方程进行离散化和配位，并给出了前缘粘滑过渡点处的力平衡条件和剪切牵引平滑条件。然后，开发了迭代算法来处理所得到的代数系统，特别是关于离散的接触压力和摩擦牵引力。本文根据已有文献结果对所提出的求解方法和数值算法进行了严格验证，证明了其准确性和可靠性。此外，它还进行了广泛的参数研究，以揭示各种参数的影响，如表面材料性能、摩擦系数、不均匀性指数和指数级渐变涂层的厚度。这些分析揭示了地表效应在形成接触压力、摩擦牵引力、应力、沉降分布和粘滑带方面的重要作用。值得注意的是，表面效应的加入减少了最大应力和沉降，同时引起了棒区向滚动方向的移动。梯度涂层性能的参数化探索也为定制梯度纳米结构的纳米接触响应提供了见解。

Orientation-related and temperature-dependent continuous grain boundary migration in multi-principal element alloys

Hao Hu, Tao Fu, Chuanying Li, Mengye Duan, Deqiang Yin, Shayuan Weng, Xianghe Peng

doi:10.1016/j.mechmat.2024.105132

多主元素合金中取向相关和温度相关的连续晶界迁移

Grain boundaries (GBs) significantly affect the mechanical properties of metals and alloys. In this study, we investigated using molecular dynamic simulations the migration behavior of Σ25 (710), Σ5 (310), and Σ37 (750) [001] symmetric tilt GBs in CoCrCuFeNi multi-principal element alloy (MPEA) and Cu samples subjected to shear deformation. In Cu, the migration of the GBs exhibits a coupled migration pattern, consistent with the Cahn model; while in MPEA, the migration pattern varies with GB angle and temperature. Both Σ25 (710) and Σ37 (750) GBs, along with higher temperatures, induce GB roughening and continuous migration in the MPEA samples. Further investigation to the effects of GB angle and temperature was conducted through microstructure evolution tracing and quantitative analysis. A model was developed to describe the temperature-dependent continuous GB migration and average flow stress in MPEA samples with Σ25 (710) or Σ37 (750) GBs. This work can help understand the mechanical behavior of GB in MPEA and provide valuable insights for the development of high-performance materials.

晶界对金属和合金的力学性能有重要影响。在本研究中，我们利用分子动力学模拟研究了Σ25(710)、Σ5(310)和Σ37(750)[001]对称倾斜GBs在CoCrCuFeNi多主元素合金(MPEA)和Cu试样中剪切变形的迁移行为。在Cu中，GBs的迁移表现为耦合迁移模式，符合Cahn模型;而在MPEA中，迁移模式随GB角和温度的变化而变化。Σ25(710)和Σ37 (750) GB随着温度升高，在MPEA样品中诱导GB粗化和连续迁移。通过显微组织演化追踪和定量分析，进一步研究了GB角和温度的影响。建立了一个模型来描述Σ25(710)或Σ37 (750) GB的MPEA样品中随温度变化的连续GB迁移和平均流动应力。这项工作有助于了解GB在MPEA中的力学行为，并为高性能材料的开发提供有价值的见解。

Thin-Walled Structures

A review on the assessment methods of bridge against ship collision

Ming Cai Xu, Tao Wang, Jin Pan

doi:10.1016/j.tws.2024.112347

桥梁抗船舶碰撞性能评估方法综述

In the past several decades, many approaches for assessing the impact load, dynamic response and safety of bridge against ship collision have been developed. The purpose of the present paper is to systematically review the relative experiments, finite element (FE) simulations and simplified analytical methods for practice application and further research. The quasi-static crushing test and impact experiments of full and reduce-scale models of ship bow and bridge are introduced firstly. The theoretical calculation formulae of ship impact force in the specifications and publications are discussed from the view point of the bridge anti-collision design. In the numerical simulations with simplified and high-resolution FE models, various influences parameters on the impact load, deformation and failure modes of bridge are presented, including the mass, angle, velocity, and type of the striking ships. The effects of geometric range, boundary condition, element type, material properties on the interaction between the ship and bridge are also illustrated. The conclusions in the experiments and numerical simulations are provided that might be useful for revising the existing assessment method of ship impact load in the specifications to improve the accuracy of results in the future, such as the influence of ship type, dynamic amplification effect.

在过去的几十年里，人们发展了许多方法来评估桥梁的冲击载荷、动力响应和抗船舶碰撞安全性。本文的目的是对相关的实验、有限元模拟和简化分析方法进行系统的综述，以供实际应用和进一步研究。首先介绍了船首和船桥全模型和缩比模型的准静态破碎试验和冲击试验。从桥梁防撞设计的角度讨论了规范和出版物中船舶冲击力的理论计算公式。采用简化的高分辨率有限元模型进行了数值模拟，给出了影响桥梁冲击载荷、变形和破坏模式的各种参数，包括撞击船舶的质量、角度、速度和类型。分析了几何范围、边界条件、单元类型、材料性能等因素对船桥相互作用的影响。实验和数值模拟的结论对今后修订规范中现有的船舶冲击载荷评估方法，提高结果的准确性(如船型影响、动力放大效应等)有一定的参考价值。

A review on energy absorption performance of auxetic composites with fillings

Qifang Hu, Xinyi Zhang, Jianjun Zhang, Guoxing Lu, Kwong Ming Tse

doi:10.1016/j.tws.2024.112348

含填料的生长型复合材料吸能性能研究进展

Auxetic materials have garnered significant attention due to their lightweight and excellent energy absorption capabilities. Nonetheless, they often display relatively lower stiffness when compared with conventional materials. To address this limitation and enhance their mechanical properties, researchers have explored various avenues, including designing hybrid auxetic structures by combining two or more auxetic unit cells and developing auxetic composites using multiple materials. While previous reviews extensively covered hybrid auxetic structures, discussing their classification, design methodologies, fabrication techniques, applications and mechanical behaviours, there has been a noticeable gap in the literature concerning auxetic composites with fillings. Therefore, this paper concentrates on auxetic composites with fillings, delving into their classifications, mechanical responses, and underlying mechanisms. This review article also critically examines different design factors that influence the performance of auxetic composites and compares them with conventional counterparts in terms of mechanisms and mechanical properties. Overall, auxetic composites exhibit superior mechanical characteristics compared to equivalent conventional materials. However, several challenges and limitations persist regarding the design, fabrication, and applications of auxetic composites.

增塑剂材料因其重量轻、能量吸收能力强而备受关注。尽管如此，与传统材料相比，它们通常表现出相对较低的刚度。为了解决这一限制并提高其机械性能，研究人员已经探索了各种途径，包括通过组合两个或多个auxics单元来设计混合auxics结构，以及使用多种材料开发auxics复合材料。虽然以前的综述广泛地涵盖了混合增塑剂结构，讨论了它们的分类、设计方法、制造技术、应用和力学行为，但关于填充增塑剂复合材料的文献却存在明显的空白。因此，本文着重研究了含填料的复合材料的分类、力学响应及其机理。这篇综述文章还批判性地考察了影响auxetic复合材料性能的不同设计因素，并将其与传统的auxetic复合材料在机理和机械性能方面进行了比较。总的来说，与等效的传统材料相比，auxetic复合材料具有优越的机械特性。然而，在设计、制造和应用方面，一些挑战和限制仍然存在。

Torsional Properties of Spiral Carbon Nanocones

Futian Xu, Haifei Zhan, Yuantong Gu, Shuyong Duan, Zirui Li

doi:10.1016/j.tws.2024.112350

螺旋碳纳米锥的扭转性能

Carbon nanostructure plays a unique role in advanced nanodevices. This work investigated the torsional properties and underlying mechanisms of spiral carbon nanocones (SCN) via atomistic simulations. The SCN exhibits four deformation stages, including linear elastic, nonlinear elastic, plastic and failure. The elastic phase is characterized by compressive stress at the inner covalent bond and tensile stress at the outer edge. The plastic transition is initiated at the innermost region, accompanied by in-plane folding. The interlayer interactions of the SCN facilitate its capacity to elicit an axial response during torsion. The resulting axial forces are governed by the layer number, cone angle, and the dimensions of both inner and outer radii. Outer radius exerts the most significant influence on SCN via the interlayer contact area. Furthermore, the inner radius and cone angle are intrinsically linked to the structural stiffness of the inner bore, which affects the axial mechanical response of the SCN during the nonlinear elastic and plastic phases. The Pearson correlation coefficient analysis has validated that these two parameters are the most crucial for SCN torsional performance. This work elucidates the prospective utility of SCN as a novel twist-to-push actuator for advanced nanodevices.

碳纳米结构在先进的纳米器件中起着独特的作用。本文通过原子模拟研究了螺旋碳纳米锥(SCN)的扭转特性及其机制。SCN呈现线性弹性、非线性弹性、塑性和破坏四个变形阶段。弹性相的特征是内共价键处的压应力和外缘处的拉应力。塑性转变始于最内层区域，伴随着面内折叠。SCN的层间相互作用促进了其在扭转期间引发轴向响应的能力。所得到的轴向力由层数、锥角和内外半径的尺寸决定。外半径通过层间接触面积对SCN的影响最为显著。此外，内半径和锥角与内孔的结构刚度有着内在的联系，这将影响SCN在非线性弹塑性阶段的轴向力学响应。Pearson相关系数分析验证了这两个参数对SCN扭转性能的影响最为关键。这项工作阐明了SCN作为先进纳米器件的新型扭推致动器的前景。

A unified dynamic stiffness modeling of multi-plate coupled systems with discrete spring connections

Zhibing Li, Tiangui Ye, Guoyong Jin, Tie jun Yang, Linghua Tian, Yukun Chen

doi:10.1016/j.tws.2024.112351

离散弹簧连接多板耦合系统的统一动刚度建模

This work presents a unified dynamic stiffness modeling for the vibration analysis of multi-plate coupled systems with discrete spring connections (MPCS-DSC). First, based on the governing differential equation of the plate, the dynamic stiffness matrix (DS) of transverse and in-plane vibration for a completely free rectangular plate is separately derived by combining the generalized superposition method and the projection method. Then, according to the continuity of displacements at the connection point between the spring and the plate, the projected DS matrix of the discrete spring is developed. Then, using an element assembly concept similar to that in the finite element method (FEM), global DS matrices of various coupled systems are determined by assembling the spring's DS matrice and the transverse or in-plane DS matrices of the plate. In order to verify the accuracy and applicability of the proposed method, the free and forced vibration analysis of four types of coupling systems is carried out. The reliability and applicability of the proposed method are confirmed by comparing the present results with those from open literature and the finite element solution. This study not only expands the application range of DS modeling theory but also provides a powerful tool to investigate the vibration characteristics of the MPCS-DSC.

本文提出了一种用于离散弹簧连接多板耦合系统(MPCS-DSC)振动分析的统一动态刚度建模方法。首先，基于板的控制微分方程，结合广义叠加法和投影法分别导出了完全自由矩形板的横向和面内振动动力刚度矩阵。然后，根据弹簧与板之间连接点位移的连续性，导出离散弹簧的投影DS矩阵。然后，采用类似于有限元法(FEM)的单元装配概念，通过将弹簧的DS矩阵与板的横向或平面内DS矩阵进行装配来确定各种耦合系统的全局DS矩阵。为了验证所提方法的准确性和适用性，对四种类型的耦合系统进行了自由振动和强迫振动分析。通过与公开文献和有限元解的比较，验证了所提方法的可靠性和适用性。本研究不仅拓展了DS建模理论的应用范围，而且为研究MPCS-DSC的振动特性提供了有力的工具。

Pure distortion of symmetric box beams with hinged walls

Carlos Lázaro, Guillermo Martínez-López, Kai-Uwe Bletzinger, Roland Wüchner

doi:10.1016/j.tws.2024.112356

对称箱梁与铰链墙的纯变形

This paper is concerned with the analysis of the pure torsion and distortion of straight box beams with trapezial cross-sections and hinged walls. A one-dimensional mechanical model for this kind of system subjected to anti-symmetric loads on the end cross-sections and no warping constraints is developed. The distortional stiffness of the system is provided by the torsional rigidity of the wall panels. The cross-sectional kinematic condition for which torsion and distortion are uncoupled has been determined. Novel explicit expressions of the internal and external distortional moments, the distortion constant, and the distortional warping pattern have been deduced; they can be directly translated to the classical distortion theory. Results of representative test cases with different section shapes and loads show excellent agreement with finite element models using shell elements. The model is a first step to analyse bridge decks with a distortionable central cell for wind engineering applications. Finally, an extension of the model, including the distortional stiffness provided by the frame bending stiffness of the cross-section walls, is presented. The extended model is applicable to assess the large-scale torsional-distortional effects in long beams with closed cross sections.

本文研究了带铰接墙的斜截面直箱梁的纯扭转和变形分析。建立了在端部截面受反对称载荷且无翘曲约束的情况下该系统的一维力学模型。系统的扭转刚度由墙板的扭转刚度提供。确定了扭转和畸变解耦的截面运动学条件。导出了内部和外部畸变矩、畸变常数和畸变畸变模式的新的显式表达式;它们可以直接转化为经典的扭曲理论。具有代表性的不同截面形状和荷载的试验结果与采用壳单元的有限元模型吻合良好。该模型是分析具有可变形中心单元的桥面用于风力工程应用的第一步。最后，对该模型进行了扩展，包括框架的弯曲刚度所提供的畸变刚度的截面墙，提出。该扩展模型适用于计算封闭截面长梁的大尺度扭扭效应。

A focused review of the draping process and its impact on the resin infusion in Liquid Composite Molding

Xing Lu, Junchun Ding, Xiongqi Peng, Guangyong Sun, Xukang Wang, Wuyang Yue, Helezi Zhou, Zhigao Huang, Huamin Zhou, Yiu Wing Mai

doi:10.1016/j.tws.2024.112362

重点综述了液体复合成型中悬垂工艺及其对树脂注入的影响

The draping process of textile reinforcements is the first and one of the most critical steps in manufacturing continuous fiber-reinforced polymer composites by Liquid Composite Molding (LCM), i.e., two-dimensional flat textiles are adapted to three-dimensional geometry. The textile deformation caused by draping will decide key physical quantities (fiber orientation, fiber volume content, and defects), significantly affecting the subsequent resin infusion behavior. Several reviews have discussed the draping process but have not establish a strong connection with the infusion process in LCM. Thus, in this focused review, we discuss the CAE chain reported in previous published literature which illustrates the significant impact of the draping process on the infusion process. A comprehensive understanding of the draping process is a prerequisite for accurately modeling the infusion process. In detail, deformation mechanisms, draping simulation approaches, and phenomena predicted by the draping process, are reviewed and discussed. Then, the impact of three deformation behaviors of textiles (shear, compaction, and defects) on the resin infusion are discussed, respectively. Finally, macroscopic infusion simulation is discussed. This review will try to identify the gaps in the draping and infusion processes and contribute to developing the CAE chain of LCM.

织物增强材料的悬垂工艺是液体复合成型(LCM)制造连续纤维增强聚合物复合材料的第一步，也是最关键的步骤之一，即使二维平面纺织品适应三维几何形状。悬垂引起的织物变形将决定关键物理量(纤维取向、纤维体积含量和缺陷)，对后续的树脂注入行为产生重大影响。几篇综述讨论了悬垂过程，但没有建立与输液过程在LCM强联系。因此，在这篇重点综述中，我们讨论了先前发表的文献中报道的CAE链，这些文献说明了悬垂过程对输液过程的重要影响。全面了解悬垂过程是准确模拟输液过程的先决条件。详细介绍了变形机制、垂折模拟方法和垂折过程预测的现象。然后，分别讨论了织物的剪切、压实和缺陷三种变形行为对树脂注入的影响。最后，对宏观输注模拟进行了讨论。本综述将试图找出悬垂和输液过程中的差距，并有助于开发LCM的CAE链。

Compressive testing and modelling of additively manufactured stainless steel equal angle sections with stiffening wave patterns

Ben Chater, Jie Wang, Mark Evernden, Jingbang Pan

doi:10.1016/j.tws.2024.112364

加强型不锈钢等角截面的压缩试验与建模

Traditional structural steel manufacturing routes typically produce prismatic members comprising of flat plate elements. Under compressive actions, the capacity of these sections is often dominated by plate instability of the lowest buckling mode. The current study involves compressive testing of 6 different configurations of non-prismatic stub columns, comprising of pre-defined surface waves tested at 3 different slendernesses and 3 amplitudes including control prismatic sections. Absolute and normalised load-displacement curves are generated to compare against the control sections and assess the potential increase in strength and stiffness, and the samples’ weights are measured to evaluate the relationship between material use and strength when using this method of strengthening. Tensile coupon tests are also carried out on coupons printed from the same material to define material parameters, and an extensive parametric study is undertaken with numerical modelling software. The best case evaluated in this study indicated a strength gain of 89.9% over a control section with an equal volume of used material. Eurocode-compatible buckling characterisation curves are then provided for two of the best performing sections. This study highlights the possibilities of this technology, paving the way towards unprecedented efficiency in future steel construction.

传统的结构钢制造路线通常生产由平板元件组成的棱柱形构件。在压缩作用下，这些截面的承载力通常由最低屈曲模态的板失稳控制。目前的研究包括6种不同配置的非棱柱短柱的压缩测试，包括预先定义的表面波，测试了3种不同的长度和3种振幅，包括控制棱柱部分。生成绝对和归一化载荷-位移曲线，与控制截面进行比较，评估强度和刚度的潜在增加，并测量样品的重量，以评估使用这种强化方法时材料使用与强度之间的关系。还对由相同材料打印的张票进行了拉伸张票试验，以确定材料参数，并使用数值模拟软件进行了广泛的参数研究。本研究中评估的最佳情况表明，与使用相同体积的材料的对照部分相比，强度增加了89.9%。然后为两个性能最好的截面提供了符合欧洲规范的屈曲特征曲线。这项研究强调了这项技术的可能性，为未来钢结构前所未有的效率铺平了道路。

Energy Absorption Characteristics of Fractal Multi-cell Square Tubular Structures under Axial Crushing

Ngoc San Ha, Ting-Uei Lee, Hongjia Lu, Jie Li, Guoxing Lu, Yi Min Xie

doi:10.1016/j.tws.2024.112365

轴向破碎作用下分形多室方管结构的吸能特性

In this study, a new fractal multi-cell square tube (FMST) based on the fractal design of the Sierpinski carpet is proposed for energy absorption. The dynamic crushing performance and energy absorption characteristics of the FMST are numerically and theoretically investigated. Extensive numerical simulations are carried out for the FMST structures with different fractal orders and masses of the structures. The findings reveal that the specific energy absorption of the 3rd order FMST is significantly higher, exhibiting a remarkable 100% increase compared to the 0th order FMST. Furthermore, the undulation of the load-carrying capacity of the 3rd order FMST is reduced by up to 88.5% compared to a conventional square tube, indicating the substantial potential of the FMST for designing highly efficient energy absorbers. Comparative analysis against other hierarchical multi-cell square tubes reported in the literature confirms that the specific energy absorption of the FMST surpasses existing designs. In addition, a theoretical study is presented for the mean crushing force of the proposed FMST, employing the simplified super folding element theory. The theoretical predictions agree well with the numerical results, further validating the effectiveness of the proposed design. This study provides an innovative design of a multi-cell energy absorber with exceptional energy absorption efficiency. The incorporation of fractal principle in the FMST design holds promise for advancing the field of energy absorption, with potential applications in various industries.

本文在Sierpinski地毯分形设计的基础上，提出了一种新的分形多孔方管(FMST)吸能结构。对FMST的动态破碎性能和吸能特性进行了数值和理论研究。对不同分形阶数和结构质量的FMST结构进行了广泛的数值模拟。结果表明，三阶FMST的比能量吸收显著高于零阶FMST，比能量吸收显著提高100%。此外，与传统的方管相比，三阶FMST承载能力的波动幅度降低了88.5%，表明FMST在设计高效吸能器方面具有巨大的潜力。与文献报道的其他分层多单元方管的比较分析证实，FMST的比能量吸收优于现有设计。此外，采用简化的超折叠单元理论对所提出的FMST的平均破碎力进行了理论研究。理论预测与数值结果吻合较好，进一步验证了所提设计的有效性。本研究提供了一种具有特殊能量吸收效率的多电池能量吸收器的创新设计。分形原理在FMST设计中的应用有望推动能量吸收领域的发展，在各个行业都有潜在的应用前景。