ABSTRACT

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.

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