Nonlinear vibration energy harvesting by intentional excitation of high-frequency dynamical instability

Abstract

In this thesis, a vibration-based energy harvesting system utilizing essential (nonlinearizable) nonlinearities and various electromechanical coupling elements is investigated. These elements include electromagnetic and piezoelectric methods of energy conversion. The mechanical system of interest consists of a grounded, weakly damped linear oscillator (primary system) subjected impulsive loading. This primary system is coupled to a lightweight, damped oscillating attachment (nonlinear energy sink, NES) via a thin wire, which generates an essential geometric cubic sti ness nonlinearity. Various electromechanical coupling elements are included within the oscillator coupling in various con gurations depending on the system being studied. Under single or repeated impulsive input, the damped dynamics of this system exhibit transient resonance captures (TRCs) causing large-amplitude, high-frequency instabilities in the response of the NES. These TRCs result in strong energy transfer from the directly excited primary system to the light-weight attachment. The energy is harvested by the electromechanical elements in the coupling and, in this present case, dissipated across a resistive element in the electrical circuit. The primary goal of this work is to numerically, analytically, and experimentally demonstrate the e cacy of employing this type of high-frequency dynamic instability to achieve enhanced vibration energy harvesting under single or repeated impulsive excitation