Instabilities in highly deformable systems: unique opportunities for control of flow and vibrations

一类具有可调不稳定性的新型有源器件正从柔性结构的设计领域中涌现出来，用于执行器、自适应系统和自调节流体的设计。然而，可用的表征技术仅限于传统材料，有前途的功能仍有待探索。该研究项目由哈佛大学K. Bertoldi研究小组开展，旨在利用非线性结构的最新研究成果，提高我们对现代材料的理解和科学分类，并扩展调谐不稳定性在各种环境中的应用领域。在子项目I中，模拟了充满流体的高度可变形结构的动态过程，并与几何和材料特性相关。可逆的独特机会，剧烈的压实允许覆盖软结构，紧凑的材料，以及两者之间的混合。这种统一的方法将传统的表征技术（例如无损参数识别，临界频率预测）扩展到新的结构。在子项目II中，非线性谐振器嵌入在应变控制的屈曲单元中。局部谐振腔的光谱丰富度由可展开单元结构的屈曲调节，从而产生具有各种可调衰减机制的新型功能超材料。对最有前途的几何形状的数值和实验测试将证明优化设计的鲁棒性和适用性。

A novel class of active devices with tuned instabilities is emerging from the exciting field of compliant structures for the design of actuators, adaptive systems, and self-regulating fluidics. Yet, available characterization techniques are restricted to conventional materials and promising functionalities remain to be explored. This research project at the research group of K. Bertoldi (Harvard University) aims at exploiting latest research on non-linear structures to sharpen our understanding and scientific classification of modern materials and to extend the application areas of tuned instabilities in various environments.In subproject I, the dynamic processes in fluid-filled, highly deformable structures are simulated and related to geometric and material properties. The unique opportunity of reversible, drastic compaction allows to cover soft structures, compact materials, and hybrids in between. This unifying approach extends conventional characterization techniques (e.g. nondestructive parameter identification, prediction of critical frequencies) to novel structures.In subproject II, non-linear resonators are embedded in strain-controlled buckling cells. The spectral richness of local resonators is regulated by the buckling of the deployable cell structure, yielding a new functional meta-material with various tunable attenuation regimes. Numerical and experimental tests of the most promising geometries will prove the robustness and applicability for an optimized design.