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Modified energy harvesting figures of merit for stress- and strain-driven piezoelectric systems

Published version
Peer-reviewed

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Authors

Roscow, JI 
Pearce, H 
Khanbareh, H 
Kar-Narayan, Sohini  ORCID logo  https://orcid.org/0000-0002-8151-1616
Bowen, CR 

Abstract

© 2019, The Author(s). Piezoelectrics are an important class of materials for mechanical energy harvesting technologies. In this paper we evaluate the piezoelectric harvesting process and define the key material properties that should be considered for effective material design and selection. Porous piezoceramics have been shown previously to display improved harvesting properties compared to their dense counterparts due to the reduction in permittivity associated with the introduction of porosity. We further this concept by considering the effect of the increased mechanical compliance of porous piezoceramics on the energy conversion efficiency and output electrical power. Finite element modelling is used to investigate the effect of porosity on relevant energy harvesting figures of merit. The increase in compliance due to porosity is shown to increase both the amount of mechanical energy transmitted into the system under stress-driven conditions, and the stress-driven figure of merit, FoM33X, despite a reduction in the electromechanical coupling coefficient. We show the importance of understanding whether a piezoelectric energy harvester is stress- or strain-driven, and demonstrate how porosity can be used to tailor the electrical and mechanical properties of piezoceramic harvesters. Finally, we derive two new figures of merit based on the consideration of each stage in the piezoelectric harvesting process and whether the system is stress- (FijX), or strain-driven (Fijx).

Description

Keywords

49 Mathematical Sciences, 51 Physical Sciences, 7 Affordable and Clean Energy

Journal Title

European Physical Journal: Special Topics

Conference Name

Journal ISSN

1951-6355
1951-6401

Volume Title

228

Publisher

Springer Science and Business Media LLC
Sponsorship
European Research Council (639526)