Rotational Energy Harvesting (High Energy Orbital Oscillations)

Abstract

This thesis presents the conception, design, and experimental validation of a rotational piezoelectric energy harvesting system that utilises high-energy orbital oscillations to capture broadband mechanical energy from rotation situated within vibrational environments. The work addresses the long-standing challenge of narrow operational bandwidth in traditional rotational harvesters by introducing a dual-mode nonlinear mechanism that transitions between gravitational excitation and magnetically induced bi-stability depending on the angular velocity.
At low rotational speeds, the harvester operates in a gravitational mode, where a freely moving magnet cyclically perturbs a piezoelectric cantilever via magnetic coupling, enabling efficient energy extraction from slow rotations. As the rotational velocity increases, centripetal forces axially dominate the cantilevers, establishing a bi-stable potential landscape through magnetic repulsion and axial loading. This condition induces amplitude-independent snap-through oscillations between potential wells that is relatively agnostic to precise value of excitation frequency, generating large-amplitude responses and broadening the operational frequency range. Analytical modelling, supported by finite element simulations, demonstrates the interplay between gravitational and centripetal nonlinearities, confirming the onset of bistability and validating the system’s dynamics across a wide range of rotational speeds.
A series of experimental prototypes was developed using PVDF and PVDF-TrFE + BTO composite cantilevers, with composite sample fabrication performed by the collaborating materials team in Japan, and their performance was assessed under band-limited noise, aerospace, automotive, and infrastructure vibration conditions. Results show that device orientation has a measurable effect on performance: the cantilever-downward configuration delivered ~10.5% higher power density than the upward configuration under comparable excitation, confirming orientation-dependent dynamics. Spectral analyses (FFT and STFT) further verified the broadband nature of the response.
Collectively, the research establishes a unified nonlinear framework for broadband rotational energy harvesting through high-energy orbital oscillations. The proposed architecture offers a lightweight, compact, and adaptable solution for self-powered sensing in aerospace, automotive, and structural-health-monitoring applications. By integrating gravitational, magnetic, and centripetal nonlinearities within a single platform, this work advances the state of the art in sustainable, autonomous power generation for diverse and dynamically varying environment.

Date of Award	Feb 2026
Original language	English
Awarding Institution	Aston University
Supervisor	Yu Jia (Supervisor) & Xianghong Ma (Supervisor)