Programming and physical realization of extreme three-dimensional responses of metastructures under large deformations
Programming and physical realization of extreme three-dimensional responses of metastructures under large deformations
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DOI：
10.1016/j.ijengsci.2023.103881
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发表时间：
2023-06-12
影响因子：
6.6
通讯作者：
Zhang, Xiaojia Shelly
中科院分区：
文献类型：
--
作者：
Li, Weichen;Jia, Yingqi;Zhang, Xiaojia Shelly
具有可编程机械响应的结构和材料对于许多应用是期望的。已经取得了很大的进步，并导致发现具有非常规编程特性的亚结构/超材料。虽然大多数已建立的研究集中在二维（2D）或伪三维系统，某些复杂的变形和功能只能在三维（3D）空间中实现。缺乏对3D空间中可编程大变形运动学的全面探索可能会遗漏过多的3D变形机制，结构几何形状和复杂的响应，这些可能会导致前所未有的机械功能。本文基于多材料拓扑优化反设计方法，系统地研究了三维结构在有限变形下的几种精确编程的非线性极值响应。发现了具有独特变形能力的复杂3D几何形状。在单调加载条件下，可以产生自恢复的反向旋转和连续的侧向膨胀-收缩等极端行为，这是二维结构无法达到的。相关机制充分利用3D空间，并最佳地利用自由形状的几何形状，材料非线性，材料特性的巨大差异和大旋转来提供目标响应。一些机制在空间上是异构的，在时间上是异步的，在空间上由一系列的子机制组成。尽管具有复杂的几何形状，但通过结合3D打印和铸造为3D几何形状量身定制的混合制造方法精确地制造了具有多相和异质机制的优化结构，并且验证了设计的独特编程行为。实验测得的响应与规定的目标和数值编程的响应高度一致。所发现的独特的3D变形模式和设计，潜在的机制，定制的3D制造方法和实验程序可以为实现完全利用3D空间的面向功能的机械元结构/超材料提供有意义的力学见解和指导方针。
Structures and materials with programmable mechanical responses are desirable for many applications. Great advancement has been achieved and led to the discovery of metastructures/metamaterials with unconventional programmed properties. While most established studies focus on two-dimensional (2D) or pseudo-three-dimensional systems, certain complex deformations and functionalities can only be realized in three-dimensional (3D) space. The lack of comprehensive exploration of programmable large-deformation kinematics in 3D space could leave out a plethora of 3D deformation mechanisms, structural geometries, and complex responses that may lead to unprecedented mechanical functionalities. Based on multimaterial inverse design by topology optimization, this study systematically investigates several precisely programmed nonlinear extreme responses in 3D structures under finite deformations. Sophisticated 3D geometries with unique deformation capabilities are discovered. Under monotonic loading, extreme behaviors such as self-recovering counter-rotation and sequential lateral expansion-contraction are created, which are beyond the reach of 2D structures. The associated mechanisms fully exploit 3D space and optimally harness freeform geometries, material nonlinearity, the large disparity in material properties, and large rotations to deliver the target responses. Some discovered mechanisms are heterogeneous in space and asynchronous in time, spatially consisting of a series of sub-mechanisms. Albeit with complex geometries, the optimized structure with multi-phase and heterogeneous mechanisms is accurately fabricated through a proposed hybrid fabrication method tailored for 3D geometries combining 3D printing and casting, and the design's unique programmed behavior is validated. The experimentally measured response shows high agreement with the prescribed target and numerically programmed responses. The discovered unique 3D deformation patterns and designs, underlying mechanisms, tailored 3D fabrication approach, and experimental procedures could provide meaningful mechanics insights and guidelines for realizing function-oriented mechanical metastructures/metamaterials that fully harness 3D space.