Stiffness nonlinearity as a means for resonance frequency tuning and enhancing mechanical robustness of vibration power harvesters

Abstract

This paper addresses a particular type of power harvesting in which energy in the periodic movement of structures is parasitically converted to stored electric charge. In such applications, tuning of the vibration power harvesters' resonance frequency is often required to match the host structures' forcing frequency. This paper presents a method of adjusting the boundary conditions of nonlinear stiffness elements as a means of tuning the resonance frequency of piezoelectric vibration power harvesters (altering the deformation mode from bending to in-plane stretching). Using this tuning method, the resonance frequency was experimentally varied between 56 and 62 Hz. For a vibration level of 2 mm/s, the harvester has a similar Q to a linear system but its Q is reduced by one third at a vibration level of 10 mm/s. This behavior is important for applications where high sensitivity is required for low vibration levels but mechanical robustness is required for high vibration levels.

Toward Broadband Vibration-based Energy Harvesting

“…A similar investigation was pursued by Loverich et al (2008), in which the resonance can be tuned by adjusting the pre-deflection of the circular plate, as shown in Figure 10. The resonance frequency could be experimentally varied between 56 and 62Hz by adjusting the boundary location by approximately 0.5mm.…”

A review on frequency tuning methods for piezoelectric energy harvesting systems

“…Loverich et al 47 also investigated such a tunable device, in which the resonance can be tuned by adjusting the pre-deflection of a circular plate. Fig.…”

Experimental study on a wide-band piezoelectric energy harvester with rotating beams vibrating in perpendicular directions

“…To resolve this critical problem, many methods have been proposed. They can be divided into two major category: active tuning technique [17][18][19][20][21][22][23] and operational frequency bandwidth widening technique [24][25][26][27][28][29][30]. The active tuning technique could ideally track the excitation frequency and adjust the operation frequency automatically to match the excitation frequency to achieve a maximum power.…”