The field of microand nano-mechanics for both solid-state and biological materials continues to attract tremendous interest. At these length scales, innovative experimental methods are continually being developed, including in-situ electron microscopy, super-resolution florescence microscopy, scanning probe microscopy and spectroscopy, and traction force microscopy. Novel microand nano-materials are also emerging, from thin films to nanowires, nanotubes, and twodimensional (2D) materials to microand nano-lattice structures to active soft materials, all of which can exhibit size effects in elastic and inelastic properties as well as sizedependent deformation and fracture mechanisms. Conversely, fundamental studies at the microand nanoscale can be critical to the design of large-scale materials. The overall goal of this special issue in Experimental Mechanics is to highlight some recent advances in this exciting field of research. In this special issue, we present fourteen papers, which include one review paper and thirteen research papers. It starts with the review paper by Liechti that summarizes recent progress in characterizing the interfacial mechanical behavior of 2D materials. 2D materials, crystalline materials consisting of a single or few layer(s) of atoms, have received significant attention recently. Interfacial mechanics (adhesion and friction) is essential for integrated device applications of 2D materials. Future research needs and opportunities on interfacial mechanics of 2D materials are discussed. The issue then moves to the thirteen research papers, which are grouped into three categories – micromechanics, nanomechanics, and cell mechanics. The section on micromechanics includes several papers on the mechanical behavior of materials at the microscale. Digital image correlation (DIC) is a powerful technique to provide full-field displacement and strain maps, which has been extended recently to the microscale. In A high resolution digital image correlation study under multiaxial loading, Polatidis et al. apply DIC to high-resolution images from electron backscatter diffraction in a scanning electron microscope (SEM). The quantitative strain maps provide valuable insights into slip systems under equibiaxial and uniaxial loading. In another article using in-situ SEM testing, In situ micromechanical characterization of metallic glass microwires under torsional loading, Fan et al. report the torsional behavior of Fe-Cobased metallic glass microwires. Both spiral stripes and shear bands are found to contribute to the fracture mechanisms. Xray computed tomography (CT) has also been used to obtain high-resolution three-dimensional descriptions of samples. In A multi-loading, climate-controlled, stationary ROI device for in-situ X-ray CT hygro-thermo-mechanical testing, Vonk et al. develop an in-situ CT device to enable advanced hygrothermal-mechanical tests on specimens subjected to multiple loading modes while controlling and measuring force, displacement, temperature, and relative humidity in real time. The potential for the new CT device is demonstrated by investigating the creasing, folding, and relaxation processes of cardboard within a climate-controlled environment. X-ray methods have also shown utility for assessing residual stresses in multilayer thin films. In Residual stresses in Cu/Ni multilayer thin films measured using the sin2ψ method, McDonald et al. use X-ray diffraction and the sin2ψ method to investigate residual stresses in magnetron-sputtered Cu/Ni multilayer thin films. The findings not only show that residual stress in metal multilayers is strongly dependent on film thickness, but more generally, demonstrate the efficacy of the method when peak broadening and overlapping issues are addressed. Finally, it is important to quantitatively understand the relationship between the population of critical flaws and the distribution of strength in a component. In Material flaw populations and component strength distributions in the context of the Weibull function, Cook and DelRio derive a model linking the parameters describing the flaw population and those describing the strength distribution of components. The model is applied to three sets of microand nano-scale silicon * Y. Zhu yzhu7@ncsu.edu

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微、纳米和细胞力学的最新进展

固态和生物材料的微纳米力学领域继续引起极大的兴趣。在这些长度尺度上，不断开发创新的实验方法，包括原位电子显微镜、超分辨率荧光显微镜、扫描探针显微镜和光谱学以及牵引力显微镜。新型微纳米材料也在不断涌现，从薄膜到纳米线、纳米管和二维 (2D) 材料，再到微纳米晶格结构，再到活性软材料，所有这些都可以在弹性和非弹性特性以及尺寸相关性方面表现出尺寸效应变形和断裂机制。相反，微米和纳米尺度的基础研究对于大型材料的设计至关重要。本期《实验力学》特刊的总体目标是强调这一激动人心的研究领域的最新进展。在本期特刊中，我们展示了 14 篇论文，其中包括一篇综述论文和 13 篇研究论文。首先是 Liechti 的综述论文，该论文总结了表征二维材料界面力学行为的最新进展。二维材料，即由单层或几层原子组成的晶体材料，最近受到了极大的关注。界面力学（粘附和摩擦）对于二维材料的集成设备应用至关重要。讨论了二维材料界面力学的未来研究需求和机会。然后，问题转向 13 篇研究论文，这些论文分为三类——微观力学、纳米力学和细胞力学。微观力学部分包括几篇关于材料在微观尺度上的力学行为的论文。数字图像相关 (DIC) 是一种强大的技术，可提供全场位移和应变图，最近已扩展到微尺度。在多轴载荷下的高分辨率数字图像相关性研究中，Polatidis 等人。将 DIC 应用于扫描电子显微镜 (SEM) 中电子背散射衍射的高分辨率图像。定量应变图为了解等双轴和单轴载荷下的滑移系统提供了宝贵的见解。在另一篇使用原位 SEM 测试的文章中，在扭转载荷下金属玻璃微丝的原位微机械表征，Fan 等人。报告了铁钴基金属玻璃微丝的扭转行为。发现螺旋条纹和剪切带都有助于断裂机制。X 射线计算机断层扫描 (CT) 也已用于获得样品的高分辨率三维描述。在用于原位 X 射线 CT 湿热机械测试的多负载、气候控制的固定 ROI 设备中，Vonk 等人。开发原位 CT 设备，以对承受多种加载模式的样品进行先进的湿热机械测试，同时实时控制和测量力、位移、温度和相对湿度。通过在气候控制环境中研究纸板的折痕、折叠和松弛过程，证明了新 CT 设备的潜力。X 射线方法还显示出用于评估多层薄膜中的残余应力的效用。在使用 sin2ψ 方法测量的 Cu/Ni 多层薄膜中的残余应力中，McDonald 等人。使用 X 射线衍射和 sin2ψ 方法研究磁控溅射 Cu/Ni 多层薄膜中的残余应力。研究结果不仅表明金属多层膜中的残余应力强烈依赖于薄膜厚度，而且更普遍地证明了该方法在解决峰展宽和重叠问题时的有效性。最后，重要的是要定量地了解关键缺陷的数量与部件中强度分布之间的关系。在 Weibull 函数上下文中的材料缺陷种群和组件强度分布中，Cook 和 DelRio 推导出一个模型，将描述缺陷总体的参数与描述组件强度分布的参数联系起来。该模型应用于三组微纳米级硅* Y. Zhu yzhu7@ncsu.edu