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

人工制造的水下运动装置仍然无法与鱼类的快速敏捷游泳能力相媲美。鱼利用其活动身体和鳍的分布式灵活性来游泳和导航，这是使用传统的基于致动器的设计难以实现的。宏观纤维复合压电材料能够实现分布式致动运动，其可以模仿复杂的鱼类运动。这些高效的活性材料可以进行定制和驱动，以产生各种结构运动，从而提供一种独特的方法来系统地探索活性结构产生的复杂三维流体动力学流动。该项目将采用实验和计算建模来了解如何利用主动压电材料设计仿生水下推进器。该项目将通过新的和现有的课程和参与研究来推进本科生和研究生的工程教育。参加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，结构动力学和振动，机电系统，智能结构和数值方法的基础知识。该项目旨在获得一个基本的理解，非定常流体动力学流动所产生的主动弹性板与内部压电驱动，经历复杂的多模态振荡的粘性流体。该项目的假设是，通过结合内部驱动的弯曲和扭曲模式，有可能产生具有定制的水动力合力的大小和方向的流体流动。完全耦合的三维模拟将与使用压电宏纤维复合材料结构的实验相结合，以探索层流状态下内部驱动电弹性板的新型多模态流体动力学。具体而言，研究将集中在共振振荡导致大幅结构变形的流体动力学。柔性压电复合材料板将被开发、测试和表征，以有效地在不同的弯曲和弯曲-扭转组合模式下操作。这些内部驱动的复合材料的水弹性行为将进行彻底的研究，以建立驱动模式和所产生的水动力和流型之间的联系。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。本研究的结果将推进目前的知识的弹性流体动力学的内部驱动的弹性材料的应用在生物启发的运动，变形，流量控制，传感和能量收集的最先进的扩展到复杂的结构运动，再加上三维流体动力学模拟。特别是，研究结果将提供基础知识，使前所未有的水上机器人鳍采用多模态运动的发展。由于压电是一个可逆的过程，该项目的结果将对其他新兴领域产生影响，例如非稳定流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.