Yang Nan, Silverberg Jesse L
Tianjin Key Laboratory of the Design and Intelligent Control of Advanced Mechatronical Systems, Tianjin University of Technology, Xiqing District, Tianjin 300384, China;
Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115
Proc Natl Acad Sci U S A. 2017 Apr 4;114(14):3590-3595. doi: 10.1073/pnas.1620714114. Epub 2017 Mar 20.
A defining feature of mechanical metamaterials is that their properties are determined by the organization of internal structure instead of the raw fabrication materials. This shift of attention to engineering internal degrees of freedom has coaxed relatively simple materials into exhibiting a wide range of remarkable mechanical properties. For practical applications to be realized, however, this nascent understanding of metamaterial design must be translated into a capacity for engineering large-scale structures with prescribed mechanical functionality. Thus, the challenge is to systematically map desired functionality of large-scale structures backward into a design scheme while using finite parameter domains. Such "inverse design" is often complicated by the deep coupling between large-scale structure and local mechanical function, which limits the available design space. Here, we introduce a design strategy for constructing 1D, 2D, and 3D mechanical metamaterials inspired by modular origami and kirigami. Our approach is to assemble a number of modules into a voxelized large-scale structure, where the module's design has a greater number of mechanical design parameters than the number of constraints imposed by bulk assembly. This inequality allows each voxel in the bulk structure to be uniquely assigned mechanical properties independent from its ability to connect and deform with its neighbors. In studying specific examples of large-scale metamaterial structures we show that a decoupling of global structure from local mechanical function allows for a variety of mechanically and topologically complex designs.
机械超材料的一个决定性特征是其属性由内部结构的组织方式而非原始制造材料决定。这种对工程内部自由度的关注转变，使得相对简单的材料展现出了广泛的卓越机械性能。然而，要实现实际应用，这种对超材料设计的初步理解必须转化为设计具有规定机械功能的大规模结构的能力。因此，挑战在于在使用有限参数域的同时，将大规模结构所需的功能系统地逆向映射到设计方案中。这种“逆向设计”通常因大规模结构与局部机械功能之间的深度耦合而变得复杂，这限制了可用的设计空间。在此，我们介绍一种受模块化折纸和剪纸启发的构建一维、二维和三维机械超材料的设计策略。我们的方法是将多个模块组装成一个体素化的大规模结构，其中模块的设计具有比整体组装所施加的约束数量更多的机械设计参数。这种不等式允许整体结构中的每个体素被唯一地赋予与其与相邻体素连接和变形能力无关的机械属性。在研究大规模超材料结构的具体示例时，我们表明全局结构与局部机械功能的解耦允许进行各种机械和拓扑复杂的设计。
