The multi-scale nature of architectured materials raises the need for advanced experimental methods suitable for the identification of their effective properties, especially when their size is finite and they undergo extreme deformations. The present work demonstrates that state-of-the art image processing methods combined with numerical and analytical models provide a comprehensive quantitative description of these solids and their global behaviour, including the influence of the boundary conditions, of the manufacturing process, and of geometric and constitutive non-linearities. To this end, an adapted multi-scale digital image correlation analysis is used to track both elongations and rotations of particular features of the unit cell at the local and global (homogenized) scale of the material. This permits to observe with unprecedented clarity the strains for various unit cells in the structure and to detect global deformation patterns and heterogeneities of the homogenized strain distribution. This method is here demonstrated on elastic sheets undergoing extreme longitudinal and shear deformations. These experimental results are compared to non-linear finite element simulations, which are also used to evaluate the effects of manufacturing imperfections on the response. A skeletal representation of the architectured solid is then extracted from the experiments and used to create a purely-kinematic truss-hinge model that can accurately capture its behaviour. The analysis proposed in this work can be extended to guide the design of two-dimensional architectured solids featuring other regular, quasi-regular or graded patterns, and subjected to other types of loads.

中文翻译：

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软结构板材极端变形的系统两尺度图像分析

建筑材料的多尺度性质提出了对适用于识别其有效性能的先进实验方法的需求，尤其是当它们的尺寸有限且经历极端变形时。目前的工作表明，最先进的图像处理方法与数值和分析模型相结合，提供了对这些固体及其整体行为的全面定量描述，包括边界条件、制造过程以及几何和本构非线性。为此，采用经过调整的多尺度数字图像相关分析来跟踪材料局部和全局（均质化）尺度下晶胞特定特征的伸长率和旋转。这允许以前所未有的清晰度观察结构中各种单元的应变，并检测均匀应变分布的全局变形模式和异质性。该方法在经历极端纵向和剪切变形的弹性片材上进行了演示。这些实验结果与非线性有限元模拟进行了比较，非线性有限元模拟也用于评估制造缺陷对响应的影响。然后从实验中提取建筑实体的骨架表示，并用于创建可以准确捕获其行为的纯运动学桁架铰链模型。这项工作中提出的分析可以扩展到指导具有其他规则、准规则或渐变图案的二维结构实体的设计，