A Microtwist Theory of Polarized Mechanical Metamaterials: Modeling and Experiments

偏振机械超材料的微扭曲理论：建模和实验

• 批准号: 1930873
• 负责人: Guoliang Huang
• 金额: $ 25万
• 依托单位: University of Missouri-Columbia
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-01 至 2023-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1930873&HistoricalAwards=false
• 关键词: Microtwist; Theory; Polarized; Mechanical; Metamaterials

Lattice-based metamaterials are materials that have a defined architecture reminiscent of atomic lattices but at a larger length scale. These materials oftentimes display unique capabilities that can be traced back to their micro-architected design. Modern advances in fabrication techniques together with increasingly environmentally conscious design constraints have motivated research in lattice-based mechanical metamaterials, which offer a range of properties unusual to natural materials. To enable their use, it is mandatory to build a fine understanding of how the composition, geometry and overall morphology of the underlying truss govern the mechanical properties desired and targeted on the macroscopic scale (centimeter to meter). This proposal aims to design, model and test lattice metamaterials that are polarized: while featuring the same microstructure everywhere, they still manage to be soft to indentation on one side but hard on the opposite side. While electric polarization is a classical concept of continuum electrodynamics, mechanical polarization in elastostatics and elastodynamics has escaped the scope of earlier theories. The theory developed through this research effort should thus be a new addition to the body of fundamental knowledge in the field of elasticity. The research will also include support of education through recruiting undergraduate in research and graduate students and increasing exposure of engineering students, and the general public, to revolutionary materials with microstructure.Isostatic lattices exhibit a number of infinitesimal collapse mechanisms, i.e., zero modes, that are sensitive to pre-set geometric distortions, such as twisting in Kagome lattices. In a topological transition, zero modes shift from being evenly distributed across bulk and edges to overpopulate preferential edges. In that case, the isostatic lattice displays a polarized behavior where it appears soft on one side and hard on the opposite side. The main aim of the present project is to understand the microstructural mechanisms by which polarization emerges and fades on a macroscopic scale. Focus is on polarization effects that remain dominant even when the size of the unit cell becomes infinitesimal in comparison to the whole lattice. Research efforts are structured around two goals: (1) to build a kinematically enriched continuum theory of elasticity, called ?microtwist elasticity?, capable of modeling polarization effects as well as the underlying zero modes quantitatively and qualitatively by employing suitably developed asymptotic homogenization methods; (2) to investigate the range of static and dynamic phenomena predicted by the microtwist theory and to systematically validate these predictions by mechanical testing of fabricated samples. The proposed theory should bring a fundamental new understanding of architected materials with microstructures based on isostatic lattices.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

基于晶格的超材料是具有使人联想到原子晶格的定义的结构但在更大的长度尺度上的材料。 这些材料通常显示出独特的能力，可以追溯到它们的微架构设计。 制造技术的现代进步以及日益环保的设计约束促使人们研究基于晶格的机械超材料，这种材料提供了一系列与天然材料不同的特性。 为了使其能够使用，必须对底层桁架的组成、几何形状和整体形态如何控制宏观尺度（厘米到米）上所需和目标的机械性能建立良好的理解。该提案旨在设计，建模和测试极化的晶格超材料：虽然到处都具有相同的微观结构，但它们仍然能够在一侧软到压痕，但在另一侧硬。虽然电极化是连续介质电动力学的经典概念，但弹性静力学和弹性动力学中的机械极化已经超出了早期理论的范围。因此，通过这项研究工作开发的理论应该是弹性领域基础知识的新补充。这项研究还将包括通过招募研究生和研究生来支持教育，增加工程专业学生和公众对具有微结构的革命性材料的接触。等静压晶格表现出许多无穷小的坍塌机制，即，零模式，这是敏感的预设几何失真，如扭曲的Kagome晶格。在拓扑转换中，零模式从均匀分布在主体和边缘上转变为过度填充优先边缘。在这种情况下，均衡晶格显示出极化行为，其中一侧显得软，另一侧显得硬。本项目的主要目的是了解微观结构的机制，极化出现和消失在宏观尺度上。重点是极化效应，保持主导地位，即使当单位细胞的大小变得无穷小相比，整个晶格。研究工作是围绕两个目标：（1）建立一个运动学丰富的连续弹性理论，称为？微扭弹性？，能够模拟极化效应以及潜在的零模式定量和定性采用适当的发展渐近均匀化方法;（2）调查的范围内的静态和动态的现象预测的微扭转理论和系统地验证这些预测的机械测试制造的样品。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Broadband acoustic attenuation in microperforated meta-shells with ventilation

• DOI: 10.1063/5.0152725
• 发表时间: 2023-06
• 期刊: Applied Physics Letters
• 影响因子: 4
• 作者: Jiajia Chen;Yonghui Zhang;Yukai Yu;Yao Zhai;H. Nguyen;S. Tracy;Xiaoming Zhou;Guoliang Huang

Non-reciprocal Rayleigh wave propagation in space–time modulated surface

• DOI: 10.1016/j.jmps.2020.104196
• 发表时间: 2021
• 期刊: Journal of The Mechanics and Physics of Solids
• 影响因子: 5.3
• 作者: Qian Wu;Hui Chen;H. Nassar;Guoliang Huang

Microtwist homogenization of three-dimensional Pyrochlore lattices on zero modes and mechanical polarization

• DOI: 10.1016/j.jmps.2021.104564
• 发表时间: 2021-07
• 期刊: Journal of The Mechanics and Physics of Solids
• 影响因子: 5.3
• 作者: Rongyu Xia;H. Nassar;Hui Chen;Zheng Li;Guoliang Huang

A 3D Mechanism-driven Hexagonal Metamaterial: Evaluation of Auxetic Behavior

• DOI: 10.1016/j.ijmecsci.2021.106699
• 发表时间: 2021-11
• 期刊: International Journal of Mechanical Sciences
• 影响因子: 7.3
• 作者: Yutai Su;Xianchen Xu;Jing Shi;Guoliang Huang

Two-dimensional microtwist modeling of topological polarization in hinged Kagome lattices and its experimental validation

• DOI: 10.1016/j.ijsolstr.2022.111891
• 发表时间: 2022-07
• 期刊: International Journal of Solids and Structures
• 影响因子: 3.6
• 作者: Hui Chen;Shaoyun Wang;Xiaopeng Li;Guoliang Huang