【新文速递】2024年3月16日固体力学SCI期刊最新文章

 

今日更新：International Journal of Solids and Structures 1 篇，Mechanics of Materials 1 篇，International Journal of Plasticity 1 篇

International Journal of Solids and Structures

Anomalous buckling of odd elastic plates

Andi Lai, Guo Fu, C.W. Lim

doi:10.1016/j.ijsolstr.2024.112774

奇数弹性板的反常屈曲

Buckling of thin-walled structures such as plates and shells is a consequence of in-plane stress being released through out-of-plane displacements. Generally, thin-walled structures that are subjected to tension or zero stress conditions remain stable. In this article, the anomalous tension buckling and stress-free active buckling of odd elastic plates are reported, which are a novel instability caused by odd elastic effects. The latter can only occur in the form of left- or right-handed chiral deformation and it does not involve external loads or internal active stress in a critical state. We demonstrate that the chiral rotation angle deformation is responsible for the active buckling of the plates, because the energy required for instability can be obtained based on the odd elastic effect. These findings can serve as an interpretation in a novel way for the occurrence of surface morphologies with biological activities, as well as provide references for buckling designs and applications of active structures.

板和壳等薄壁结构的屈曲是平面内应力通过平面外位移释放的结果。一般来说，薄壁结构在拉伸或零应力条件下会保持稳定。本文报告了奇异弹性板的反常拉伸屈曲和无应力主动屈曲，这是一种由奇异弹性效应引起的新型不稳定性。后者只能以左旋或右旋手性变形的形式发生，在临界状态下不涉及外部载荷或内部主动应力。我们证明，手性旋转角变形是板块主动屈曲的原因，因为不稳定所需的能量可以根据奇异弹性效应获得。这些发现以一种新颖的方式解释了具有生物活性的表面形态的发生，并为活性结构的屈曲设计和应用提供了参考。

Mechanics of Materials

A novel metamaterial with instantaneously sign-switchable coefficient of thermal expansion and Poisson's ratio

Hao Wu, Minghui Fu, Mingming Chen, Wen Jiang, Rongchang Zhong, Binbin Zheng, Jingxiang Huang

doi:10.1016/j.mechmat.2024.104974

热膨胀系数和泊松比可瞬时符号切换的新型超材料

Most materials expand when heated and contract when cooled. In contrast, negative thermal expansion materials exhibit the opposite behavior. In this paper, we present a metamaterial that expands both when heated and cooled. The unit cell configuration is crafted by embedding two isosceles triangular structures composed of high thermal expansion materials within a re-entrant hexagonal honeycomb framework. Initially, the bases of the two isosceles triangles are in contact. The metamaterial exhibits two deformation states under different external loads. Analytical formulas for the equivalent parameters were derived based on classical beam theory within the regime of small deformation. Finite element simulations were conducted to validate the accuracy of these analytical formulas. The influence of geometric parameters on the metamaterial is discussed in detail. The results demonstrate that the metamaterial can exhibit excellent multi-functional properties within a small range of deformation, including instantaneous sign-variable coefficients of thermal expansion and Poisson's ratios, along with significantly distinct tensile and compressive stiffnesses. This metamaterial consistently exhibits expansive characteristics regardless of variations in ambient temperature. Additionally, the material always expands laterally regardless of the sign of uniaxial loads. Based on these properties, the metamaterial can be applied to fasteners in the aerospace industry that require permanent locking, ensuring stability in various temperature and mechanical load conditions.

大多数材料在加热时膨胀，冷却时收缩。相反，负热膨胀材料则表现出相反的行为。在本文中，我们介绍了一种在加热和冷却时都会膨胀的超材料。我们将两个由高热膨胀材料组成的等腰三角形结构嵌入一个再入六边形蜂窝框架中，从而制作出这种单元格结构。起初，两个等腰三角形的底面相接触。超材料在不同的外部载荷作用下呈现出两种变形状态。在小变形状态下，根据经典梁理论推导出了等效参数的分析公式。为了验证这些分析公式的准确性，还进行了有限元模拟。详细讨论了几何参数对超材料的影响。结果表明，该超材料可在小变形范围内表现出卓越的多功能特性，包括瞬时符号可变的热膨胀系数和泊松比，以及明显不同的拉伸和压缩刚度。无论环境温度如何变化，这种超材料始终表现出膨胀特性。此外，无论单轴载荷的符号如何，该材料始终具有横向膨胀性。基于这些特性，这种超材料可应用于航空航天工业中需要永久锁定的紧固件，确保在各种温度和机械负载条件下的稳定性。

International Journal of Plasticity

Analysis of slip transfer across grain boundaries in Ti via diffraction contrast tomography and high-resolution digital image correlation: When the geometrical criteria are not sufficient

E. Nieto-Valeiras, A. Orozco-Caballero, M. Sarebanzadeh, J. Sun, J. LLorca

doi:10.1016/j.ijplas.2024.103941

通过衍射对比断层扫描和高分辨率数字图像相关性分析钛中晶界的滑移转移：当几何标准不充分时

High-resolution digital image correlation was employed to analyze the occurrence of slip transfer across grain boundaries in pure Ti. The microstructure was characterized in 3D through diffraction contrast tomography and electron backscatter diffraction. The prismatic slip activity was captured in the shear strain maps at different strains, and the grain boundaries were classified according to the occurrence/absence of slip transfer. Different geometrical slip transfer criteria were tested, and, in general, the slip transfer likelihood increased when the slip systems across the boundary were well-aligned. Nevertheless, a detailed analysis of selected grain boundaries revealed that slip transfer could be triggered or impeded depending on the local stresses acting on the neighborhood, regardless of the alignment between the slip systems. The microstructural and deformation patterns where the geometrical criteria are not enough to predict slip transfer are assessed.

采用高分辨率数字图像相关技术分析了纯钛中发生的晶界滑移。通过衍射对比断层扫描和电子反向散射衍射对微观结构进行了三维表征。不同应变下的剪切应变图捕捉到了棱柱滑移活动，并根据滑移发生/不发生对晶界进行了分类。对不同的几何滑移标准进行了测试，一般来说，当边界上的滑移系统排列整齐时，滑移的可能性会增加。然而，对所选晶粒边界的详细分析显示，滑移转移的触发或阻碍取决于作用于邻域的局部应力，而与滑移系统之间的排列无关。在几何标准不足以预测滑移的情况下，我们对微观结构和变形模式进行了评估。