【新文速递】2023年11月27日固体力学SCI期刊最新文章

今日更新：Journal of the Mechanics and Physics of Solids 2 篇，Mechanics of Materials 1 篇，International Journal of Plasticity 1 篇，Thin-Walled Structures 1 篇

Journal of the Mechanics and Physics of Solids

Effect of roughness of a nominally plane bonded interface between dissimilar materials

J.R. Barber

doi:10.1016/j.jmps.2023.105495

不同材料之间名义平面粘接界面粗糙度的影响

A method is presented for determining the perturbation in the three-dimensional stress field due to roughness of a nominally plane bonded interface between dissimilar materials subjected to far-field uniform strains. An appropriate combination of Boussinesq potentials and arguments from symmetry reduces the problem to the solution of a harmonic boundary-value problem for the half space, where the boundary values are determined by the slope of the interface and the far-field strains. A wide range of interface shapes can be generated using combinations of classical singular harmonics such as the source solution. The method is illustrated by several examples.

本文提出了一种方法，用于确定由于受到远场均匀应变的异种材料之间的名义平面粘接界面粗糙度引起的三维应力场扰动。通过适当结合布森斯克势能和对称性参数，可将问题简化为半空间谐波边界值问题的求解，其中边界值由界面斜率和远场应变决定。利用经典奇异谐波的组合（如源解），可以生成多种界面形状。该方法通过几个实例进行了说明。

How to select discrete or continuous interfaces in biological materials to achieve a strength-toughness tradeoff

Zheyuan Yu, Peiran Li, Zhilong Peng, Yin Yao, Shaohua Chen

doi:10.1016/j.jmps.2023.105502

如何选择生物材料中的离散或连续界面，以实现强度-韧性权衡

Many biological materials, such as nacre, bone and turtle shell cuticle, can successfully achieve a tradeoff between strength and toughness, which is attributed to the stacked microstructure formed by soft and hard phases. However, among these biological materials, the soft phase-formed interfaces of some biological materials are continuous, while those of some are discrete. In this paper, a shear lag model considering an elasto-plastic discrete interface is established to reveal the selection mechanism of two kinds of interfaces in different biological materials, thus solving the tradeoff between strength and toughness. Based on the shear lag model, theoretical solutions of the stress and displacement in the hard phase and the shear stress in the soft interfacial phase are obtained for a general case with any number of interfacial bonding segments. The relationship between the effective stress and effective strain of the representative volume element (RVE) is further achieved, with the help of which the strength and toughness of staggered bio-composites can be analyzed. Corresponding experiments based on 3D-printed samples are further performed to verify the theoretical predictions. It is found that, when the hard phase and soft phase have comparable mechanical properties, like those in turtle shell cuticle, the interface guarantees a high load transfer efficiency to generate the ultimate stress in the platelet, while its discrete distribution leads to a higher interfacial shear stress level than that in a continuously bonded interface. Such a material-structure co-action induces a hybrid damage mode of hard phase fracture and soft phase failure, consequently leading to an excellent strength-toughness tradeoff. However, if the mechanical properties of two phases differ significantly, like those in nacreous materials or bone, a discrete interface should result in a unique damage mode of interface failure and a low utilization efficiency of hard phase. Instead, a continuous interface in this case is more conducive to obtain a tradeoff between strength and toughness. All the results demonstrate that biological materials choose different interface structures to meet the requirements of strength and toughness matching, based on the differences in the mechanical properties of soft and hard phases. Such a selection mechanism provides a direct reference for the optimal design of artificial composites with an excellent strength-toughness match.

许多生物材料，如珍珠质、骨和龟甲角质层，都能成功实现强度和韧性之间的权衡，这归功于由软相和硬相形成的叠层微结构。然而，在这些生物材料中，有些生物材料的软相界面是连续的，而有些则是离散的。本文建立了一个考虑弹塑性离散界面的剪切滞后模型，以揭示不同生物材料中两种界面的选择机制，从而解决强度和韧性之间的权衡问题。基于剪切滞后模型，在具有任意数量界面结合段的一般情况下，得到了硬界面相的应力和位移以及软界面相的剪切应力的理论解。并进一步得出了代表体积元素（RVE）的有效应力和有效应变之间的关系，从而分析了交错生物复合材料的强度和韧性。为了验证理论预测，还进一步基于三维打印样品进行了相应的实验。实验发现，当硬相与软相的机械性能相当时（如龟甲角质层的机械性能），交错界面可保证较高的载荷传递效率，从而在血小板中产生极限应力，而其离散分布则导致界面剪应力水平高于连续粘合界面。这种材料与结构的共同作用会诱发硬相断裂和软相破坏的混合破坏模式，从而实现极佳的强度-韧性权衡。然而，如果两相的机械性能差异很大，如珍珠质材料或骨骼，则离散界面应导致界面破坏的独特损坏模式，并降低硬相的利用效率。相反，在这种情况下，连续界面更有利于在强度和韧性之间取得平衡。所有结果都表明，生物材料会根据软硬相机械性能的差异，选择不同的界面结构来满足强度和韧性匹配的要求。这种选择机制为优化设计具有优异强度-韧性匹配的人工复合材料提供了直接参考。

Mechanics of Materials

Mechanics of hard-magnetic soft materials: A review

Lu Lu, Jay Sim, Ruike Renee Zhao

doi:10.1016/j.mechmat.2023.104874

硬磁软材料力学：综述

Hard-magnetic soft materials are a class of magnetically responsive composites obtained by embedding hard-magnetic particles into a soft polymeric matrix. They have found widespread applications in shape-morphing systems, soft robotics, biomedical devices, and active metamaterials due to their ability to feature complex, untethered, reversible, and rapid deformations in response to magnetic loads. To guide the rational design of these functional applications, extensive efforts have been devoted to studying the mechanical behavior of hard-magnetic soft materials. In this paper, we review the recent progress in the mechanics of hard-magnetic soft materials. First, we introduce existing constitutive models capable of describing the coupled magneto-elastic deformations of hard-magnetic soft materials. Then, we discuss the mechanical response of structures made of hard-magnetic soft materials, including rods, beams, plates, and shells, under mechanical and magnetic loading. Subsequently, we introduce the design and behavior of magneto-mechanical metamaterials with tunable properties enabled by hard-magnetic soft materials. In addition, optimization-guided inverse design strategies for hard-magnetic soft materials to achieve predefined properties or deformations are also briefly reviewed. Finally, we provide our views on the potential future directions in the field of mechanics of hard-magnetic soft materials. We expect the current review to guide researchers to better understand different theoretical and computational frameworks of mechanics of hard-magnetic soft materials and thus aid with designing functional systems using these materials for various applications.

硬磁软材料是通过将硬磁颗粒嵌入软聚合物基体而获得的一类磁响应复合材料。由于硬磁软材料能够在磁负荷作用下发生复杂、无束缚、可逆和快速的变形，因此被广泛应用于形状变形系统、软机器人、生物医学设备和有源超材料等领域。为了指导这些功能应用的合理设计，人们一直致力于研究硬磁软材料的机械行为。本文回顾了硬磁软材料力学的最新进展。首先，我们介绍了能够描述硬磁软材料磁弹性耦合变形的现有构成模型。然后，我们讨论了由硬磁软材料（包括棒、梁、板和壳）制成的结构在机械和磁载荷下的机械响应。随后，我们介绍了由硬磁软材料实现的具有可调特性的磁机械超材料的设计和行为。此外，我们还简要回顾了以优化为导向的反向设计策略，以实现硬磁软材料的预定义特性或变形。最后，我们对硬磁软材料力学领域未来的潜在发展方向提出了自己的看法。我们希望当前的综述能指导研究人员更好地理解硬磁软材料力学的不同理论和计算框架，从而帮助设计出使用这些材料的功能系统，并应用于各种领域。

International Journal of Plasticity

Fatigue crack growth behaviour of an additively manufactured titanium alloy: Effects of spatial and crystallographic orientations of α lamellae

Zhiying Liu, Soumya Sobhan Dash, Jiahui Zhang, Tianyi Lyu, Lizhong Lang, Daolun Chen, Yu Zou

doi:10.1016/j.ijplas.2023.103819

添加剂制造的钛合金的疲劳裂纹生长行为：α薄片的空间和晶体取向的影响

Laser-based directed energy deposition (LDED) enables the rapid near-net-shape fabrication of large-scale titanium components for aerospace applications. However, the fatigue failure of the LDED-produced titanium alloys hinders their widespread use in critical load-bearing structures subjected to cyclic loading. Here, we investigate the fatigue crack growth behaviour of LDED-produced Ti-6Al-2Zr-Mo-V alloy in both as-deposited and heat-treated states. The two states of samples consist of α and β laths with the majority of α laths showing distinct crystallographic and spatial orientations. They show distinct cracking behaviours: (i) Fatigue cracks with lengths lower than ∼400 µm grow along α/β boundaries and are surrounded by limited plastic deformations in the as-deposited sample, while in the heat-treated sample, they grow along basal or prismatic planes of the α lamellae associated with substantial plastic deformations; (ii) Fatigue cracks with lengths over ∼400 µm are primarily deflected by α/β boundaries in the as-deposited sample, but are retarded by severe plastic deformations in the heat-treated sample; (iii) Secondary cracks appear along the α/β boundaries in the as-deposited sample, whereas in the heat-treated sample, they initiate in the interior and preferentially along the prismatic plane of the α lamellae due to localized shearing and plastic deformation. The fatigue crack growth behaviours are strongly correlated with orientations (both crystallographic and spatial) and size of the α lamellae in our titanium samples. These findings highlight the significance of simultaneously tuning the spatial orientations of α lamellae and their crystallographic orientations to enhance the fatigue crack growth resistance of LDED-produced titanium alloys.

基于激光的定向能沉积（LDED）能快速制造出用于航空航天领域的大型钛部件。然而，LDED 生产的钛合金的疲劳失效阻碍了它们在承受循环载荷的关键承重结构中的广泛应用。在此，我们研究了 LDED 生产的 Ti-6Al-2Zr-Mo-V 合金在沉积和热处理两种状态下的疲劳裂纹生长行为。这两种状态的样品由 α 和 β 板条组成，其中大部分 α 板条显示出不同的晶体学和空间取向。它们表现出不同的开裂行为：(i) 长度小于 ∼400 µm 的疲劳裂纹沿着 α/β 边界生长，在析出样品中，裂纹被有限的塑性变形所包围；而在热处理样品中，裂纹沿着 α 薄片的基面或棱柱面生长，并伴有大量塑性变形；(ii) 在未轧制样品中，长度超过 ∼400 µm 的疲劳裂纹主要受 α/β 边界的影响而发生偏转，但在热处理样品中则受到严重塑性变形的阻碍；(iii) 在未轧制样品中，次生裂纹沿着 α/β 边界出现，而在热处理样品中，由于局部剪切和塑性变形，次生裂纹在内部产生，并优先沿着 α 薄片的棱柱平面产生。疲劳裂纹的生长行为与钛样品中 α 薄片的取向（晶体学和空间取向）和尺寸密切相关。这些发现突出表明，同时调整 α 片层的空间取向及其晶体学取向对于提高 LDED 生产的钛合金的抗疲劳裂纹生长性能具有重要意义。

Thin-Walled Structures

Large deformation analysis of functionally graded revolutionary shallow thin shells with bi-modular effect: Snap-through buckling under different boundary constraints

Bo Pang, Xiao-Ting He, Jun-Yi Sun

doi:10.1016/j.tws.2023.111425

具有双模块效应的功能分级革命性浅薄壳的大变形分析：不同边界约束条件下的咬合屈曲

Functionally graded materials (FGMs) enable structures to achieve a smooth transition between different material properties, providing an optimized combination of functions to meet the diversity of engineering needs. However, the presence of bi-modular effect in FGMs is often neglected due to the complexity in the analysis. In this paper, the curvature correction equivalent method based on the von Kármán theory will be applied to the theoretical study for the large deformation problem and the resulting snap-through buckling of functionally graded revolutionary shallow thin shells with bi-modular effect under different boundary constraints. Furthermore, a bi-modular FGMs user material subroutine (UMAT) is developed for the first time to simulate the real material model, thus validating the theoretical solution. The results show that except for the bi-modular effect of materials, boundary constraints of shells also have important influences on the relationship of load vs. central deflection and snap-through buckling. The research of boundary constraints brings new conclusions to snap-through buckling: the rotation constraint and radial constraint at the shell edge have opposite effects on snap-through buckling. This work will contribute to the analysis of the snap-through buckling of functionally graded revolutionary shallow thin shells with an obvious bi-modular effect and under various boundary constraints.

功能分级材料（FGMs）可使结构在不同材料特性之间实现平滑过渡，提供优化的功能组合，以满足工程的各种需求。然而，由于分析的复杂性，双模块效应在 FGM 中的存在往往被忽视。本文将应用基于 von Kármán 理论的曲率校正等效方法，对具有双模块效应的功能分级革命性浅薄壳在不同边界约束条件下的大变形问题和由此产生的快穿屈曲进行理论研究。此外，首次开发了双模块 FGMs 用户材料子程序（UMAT）来模拟真实材料模型，从而验证了理论解法。结果表明，除了材料的双模块效应外，壳体的边界约束对载荷与中心挠度的关系以及快穿屈曲也有重要影响。对边界约束的研究为通过式屈曲带来了新的结论：壳体边缘的旋转约束和径向约束对通过式屈曲的影响是相反的。这项工作将有助于分析具有明显双模块效应和各种边界约束条件下的功能分级革命性浅薄壳的快穿屈曲。