SUMMARY

This work investigates the use of flexible Macro-Fiber Composite (MFC) piezoelectric materials for bio-inspired bending-twisting actuation. The focus is placed on different piezoelectric composite architectures for flapping-wing flight and fish-like swimming applications. The MFC-based architectures studied in this work are a Double Bimorph (DB) with narrow 0-degree-fiber laminates and an Asymmetric Bimorph (AB) with 0/45-degree-laminates (for flapping-wing applications), and a Triple Bimorph (TB) with narrow 0-degree-fiber laminates to mimic a 3-degree-of-freedom (3-DOF) biomimetic caudal fin (for aquatic robotics). The DB architecture has four narrow MFC laminates forming two bimorphs with a chord-wise distance while the AB includes two wide MFC laminates with different fiber orientation. The electroelastic dynamics of these two architectures are experimentally characterized for actuation under different voltage levels through their frequency response curves covering the fundamental bending and twisting modes. Actuation power consumption levels are also recorded for each configuration and vibration mode. Moreover, solar energy harvesting using flexible films with dimensions similar to the DB and AB architectures are investigated toward self-powered flapping. Desktop wind tunnel tests are performed for the characterization of bending-twisting coupling with changing flow speed. In addition to studying the actuation capabilities, both architectures are tested for vibrational energy harvesting. The DB is also studied for active stiffness change without shape change under static actuation. The TB architecture representing a 3-DOF caudal fin is studied specifically for underwater robotic fish applications. Various actuation patterns are applied to create flat, cupping, and rolling motions. Thrust production, velocity response, and power consumption levels are recorded for a range of actuation frequencies in an effort to identify the most efficient case.