Mechanical energy from vibrations is widespread in the ambient environment. It may be harvested efficiently using triboelectric generators. Nevertheless, the harvesters' effectiveness is restricted because of the limited bandwidth. This thesis proposed a comprehensive theoretical and experimental investigation of a variable frequency energy harvester, which integrates a Vibro-impact triboelectric-based harvester and magnetic nonlinearity to increase the operation bandwidth and improve the efficiency of conventional triboelectric harvesters. A cantilever beam with a tip magnet is aligned with another fixed magnet at the same polarity to induce a nonlinear magnetic repulsive force. A triboelectric harvester is integrated into the system by utilizing the lower surface of the tip magnet to serve as the top electrode of the harvester, while the bottom electrode with an attached Polydimethylsiloxane insulator is placed underneath. Numerical simulations are performed to examine the impact of the potential wells formed by the magnets. The structure's static and dynamic behavior at varying excitation levels, separation distance, and surface charge density are all discussed. In order to develop a variable frequency system with wide bandwidth, the system's natural frequency varies by changing the distance between the two magnets to reduce or magnify the magnetic force to achieve monostable or bistable oscillations. When the system is excited by vibrations, the beams will vibrate, which will cause an impact between the triboelectric layers. This impact will produce an alternating electrical signal through periodic contact-separation motions between the harvester's electrodes. Theoretical findings were experimentally validated. The findings of this research have the potential to pave the way for developing an effective energy harvester capable of scavenging energy from ambient vibrations across a broad range of excitation frequencies. We enhanced the frequency bandwidth by 110.41 % compared to the conventional energy harvester. Combining magnetic nonlinearity and Vibro-impact can effectively broaden the operational frequency bandwidth and enhance the harvested energy for triboelectric energy harvesters.
Date of publication
Alwathiqbellah Ibrahim, Ph.D., Neal Barakat, Ph.D., Nelson Fumo, Ph.D.
Masters in Mechaical Engineering
Qaseem, Qais, "INVESTIGATION OF MAGNETIC BISTABILITY FOR A WIDER BANDWIDTH IN VIBRO-IMPACT TRIBOELECTRIC ENERGY HARVESTERS" (2023). Mechanical Engineering Theses. Paper 22.