Collaborative Research: Tailoring Energy Landscapes to Harness the Multistability for Reconfigurable 3D Buckled Structures

这笔赠款将集中在三维(3D)结构的多重稳定性的基础研究上，以实现良好控制的、主动的建筑可重构性。可重构结构可以在外界刺激(如机械力、磁场、电场、水化作用、温度和压力)的作用下主动改变其几何形状，从而改变其功能。这种智能的刺激响应型结构在可展开的太阳能电池板、电磁超材料、光子学、生物医学设备、软机器人、超表面等领域有着广泛的应用。然而，大多数现有的重构机制需要持续的外部刺激来保持变形的形状。通过利用结构不稳定性的可重构性已经成为设计各种多功能可重构器件的一种流行和强大的手段，这些器件可以在不需要持续的外部刺激的情况下保持其变形的形状。尽管人们进行了大量的研究，但实现可重构结构的可控性的困难已经严重阻碍了可重构结构的合理设计，特别是对于那些由薄膜组成的可重构结构。这一研究项目将集中于了解3D薄膜结构的几何和力学性质与其多稳定性之间的基本关系，并确定从一个稳定状态到另一个稳定状态的能效重新配置路径。除了研究活动，该项目还将通过支持跨学科博士生培训、本科生研究机会以及面向6-9年级女生和来自代表性不足群体的K-5学生的推广活动，为研究生、本科生和K-12学生的教育做出贡献。该项目的目标是揭示控制灵活、三维(3D)薄膜结构的多稳定、对称和非对称构型之间的建筑重构的基本机制。为了实现这一目标，本项目的具体目标包括：(1)通过能量景观偏置最大化3D薄膜结构的能量势垒，消除稳定状态之间的中间局部极小；(2)最小化从一个局部极小状态到另一个局部极小状态的形状变化的能量成本，并通过磁力控制实现3D薄膜结构的可重构性。这项工作的研究成果将极大地促进我们对多稳态结构力学的认识，通过(I)建立薄膜结构的几何和材料组成与不同稳态的能量图景之间的关系，以及(Ii)确定以最小能量路径有效地将结构从一个稳态操纵到另一个稳态的作用力。此外，该项目最终将促进控制良好的智能可重构结构的设计，并对其他领域产生广泛影响，包括物理、材料科学、智能材料和结构。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This grant will focus on fundamental studies on the multistability of three-dimensional (3D) structures for well-controlled, active architectural reconfigurability. Reconfigurable structures can actively change their geometries and thereby their functionalities upon external stimuli (like mechanical forces, magnetic fields, electric fields, hydration, temperature, and pressure). Such smart, stimuli-responsive structures have a diverse range of applications in deployable solar panels, electromagnetic metamaterials, photonics, biomedical devices, soft robotics, metasurfaces, and many others. Most existing reconfiguration mechanisms, however, require persistent external stimuli to maintain the deformed shape. Reconfigurability through harnessing structural instabilities has emerged as a popular and powerful means of designing various multifunctional reconfigurable devices that can maintain their deformed shape without the need for persistent external stimuli. Despite intensive studies, the difficulty in realizing well-controlled architectural reconfigurability has significantly hindered the rational design of reconfigurable structures, especially for those composed of thin films. This research project will focus on understanding the fundamental relationship between the geometry and mechanical properties of 3D thin-film structures and their multistability and identifying the energy-efficient reconfiguration path from one stable state to another. In addition to the research activities, the project will contribute to the education of students at the graduate, undergraduate, and K-12 levels by supporting interdisciplinary doctoral student training, undergraduate research opportunities, and outreach activities to grade 6-9 girls and K-5 students from underrepresented groups.The objective of this project is to unravel the fundamental mechanics that govern architectural reconfiguration among multistable, symmetric and asymmetric configurations of flexible, three-dimensional (3D) thin-film structures. To achieve this objective, the specific aims of this project include: (1) maximize the energy barrier and eliminate intermediate local minima between stable states of 3D thin-film structures through energy landscape biasing, and (2) minimize the energy cost for shape change from one local minimum state to another, and realize the reconfigurability of 3D thin-film structures through magnetic force control. The research outcomes of the work will significantly advance our knowledge in the mechanics of multistable structures by (i) establishing relations between geometries and material compositions of thin-film structures and the energy landscape of different stable states, and (ii) determining the active forces to efficiently maneuver the structure from one stable state to another following the minimum energy path. In addition, the project will ultimately facilitate the design of well-controlled, smart reconfigurable structures and generate broad impacts on other fields, including physics, materials science, and smart materials and structures.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.