Understanding 3D hydrodynamics of active electroelastic materials in complex multimodal motion

人造的水下运动装置仍然无法与鱼类快速灵活地游动的能力相媲美。鱼类利用其主动体和鳍的分布式灵活性来游泳和导航，这是传统的基于执行器的设计难以实现的。巨纤维复合压电材料实现了模拟复杂鱼类运动的分布式驱动运动。这些高效的活性材料可以定制和驱动以产生各种结构运动，从而为系统地探索由活性结构产生的复杂三维流体力学流动提供了独特的方法。该项目将采用实验和计算模型来了解如何利用主动压电材料来设计仿生水下推进器。该项目将通过新的和现有的课程以及参与研究来推进本科和研究生的工程教育。参与该项目的研究生将获得独特的实验和理论技能，并获得流体动力学，结构动力学与振动，机电系统，智能结构和数值方法的基础知识。本项目旨在对在粘性流体中经历复杂多模态振荡的具有内部压电驱动的主动弹性板产生的非定常水动力流动有一个基本的了解。该项目的假设是，通过结合内部驱动的弯曲和扭曲模式，可以产生具有特定大小和方向的流体流动。利用压电宏纤维复合材料结构的全耦合三维模拟将与实验相结合，探索层流状态下内致电弹性板的新型多模态流体力学。具体而言，研究将集中在共振振荡导致的大振幅结构变形的流体动力学。柔性压电复合板将被开发、测试和表征，以有效地在不同的弯曲和弯曲-扭转组合模式下工作。这些内部驱动复合材料的水弹性行为将被彻底研究，以建立驱动模式与产生的水动力和流动模式之间的联系。该项目将确定与水弹性耦合相关的动量传递和能量损失的物理机制。本研究的结果将推动当前关于内部驱动弹性材料的弹性流体动力学的知识，通过将最新技术扩展到复杂的结构运动，结合三维流体动力学模拟，将其应用于仿生运动，变形，流动控制，传感和能量收集。特别是，结果将提供基础知识，使前所未有的水生机器人鳍采用多模态运动的发展。由于压电是一个可逆过程，该项目的结果将对其他新兴领域产生影响，如非定常流动中的能量收集和传感。

Man-made devices for underwater locomotion still cannot match the ability of fishes to swim quickly with great agility. Fish leverage distributed flexibility of their active body and fins to swim and navigate, which is difficult to achieve using conventional actuator-based designs. Macro-fiber composite piezoelectric materials enable distributed actuation movement which may mimic complex fish motions. These efficient active materials can be tailored and actuated to create various structural motions, thereby offering a unique approach to systematically explore the complex three-dimensional hydrodynamic flows generated by active structures. This project will employ experiments and computational modeling to understand how active piezoelectric materials can be harnessed in designing biomimetic underwater propulsors. The project will advance undergraduate and graduate engineering education through new and existing courses and engagement in research. Graduate students participating in the project will obtain unique experimental and theoretical skills and acquire fundamental knowledge on fluid dynamics, structural dynamics and vibrations, electromechanical systems, smart structures, and numerical methods. This project seeks to gain a fundamental understanding of unsteady hydrodynamic flows generated by active elastic plates with internal piezoelectric actuation that undergo complex multimodal oscillations in a viscous fluid. The project hypothesis is that, by combining bending and twisting modes of internal actuation, it is possible to generate fluid flows with tailored magnitude and direction of the resultant hydrodynamic force. Fully-coupled three-dimensional simulations will be integrated with experiments using piezoelectric macro-fiber composite structures to explore the novel multimodal hydrodynamics of internally-actuated electroelastic plates in laminar flow regimes. Specifically the research will focus on the hydrodynamics of resonance oscillations leading to large-amplitude structural deformations. Flexible piezoelectric composite plates will be developed, tested, and characterized to effectively operate at different bending and combined bending-twisting modes. The hydroelastic behavior of these internally actuated composites will be thoroughly investigated to establish the connection between the actuation modes and resulting hydrodynamic forces and flow patterns. The project will identify physical mechanisms governing momentum transfer and energy losses associated with hydroelastic coupling. The results of this study will advance the current knowledge on the elastohydrodynamics of internally actuated elastic materials for applications in bio-inspired locomotion, morphing, flow control, sensing, and energy harvesting by extending the state of the art to complex structural motions coupled with three-dimensional fluid dynamics simulations. In particular, the results will provide fundamental knowledge enabling the development of unprecedented aquatic robot fins employing multimodal motions. Since piezoelectricity is a reversible process, the results of this project will have an impact on other emerging areas such as energy harvesting and sensing in unsteady flows.