Hybrid Structural Composites with Energy Harvesting Capabilities

Hybrid materials have received significant interest due to the potential enhancements they provide over traditional materials such as sensing, actuating, energy scavenging, thermal management, and vibration damping. While traditional materials can be utilized for either one of these functions or loadbearing, the hybrid materials are superior as they allow combination of a wide array of functionalities whilst being suitable for load-bearing purposes. The goal of this thesis is to elucidate the synergistic effects of hybridization of two piezoelectric materials; zinc oxide nanowires (ZnO NWs) and thin film of lead zirconium titanate (PZT) on the mechanical and energy harvesting of beams made from plain-woven carbon fiber reinforced epoxy composites (CFRPs). ZnO NWs have, by contrast, displayed great promises. While not only being a very strong piezoelectric material, it enhanced the mechanical and dynamic properties of the composite due to the increased surface area and mechanical interlocking. However, the aspect of energy scavenging is somewhat limited due to the weak piezoelectrical effects of ZnO nanowires. In this thesis, the prospects of ZnO NWs are exploited further to improve both their production processes and piezoelectric performance. Combining ZnO NWs grown on carbon fibers combined with other piezoelectrical materials has not yet been implemented but appears to be encouraging. This is the focus of this thesis. Despite that the composite comprising the combination of the two piezoelectric materials showed a minor drop in tensile strength and damping characteristics, the substantial gain in both stiffness (25.8 % increase compared to plain composite) and the electrical power gain (733.94 % more than that for ZnO NWs) is very promising for future application of the hybrid material into real engineering problems. A comprehensive study utilizing available commercial finite element software to simulate and foresee the behavior of hybrid materials was also carried out. The simulations agreed qualitatively with the experimental observations and explanations of the discrepancies between the model and experiment setup were discussed. Despite the preliminary promising results, more work is necessary to exploit the full potential of these material by optimizing the design of the energy harvesting devices and establishing more feasible models that treat the electromechanical coupling of these multifunctional hybrid composites more realistically