Investigation on the thermo‐piezo‐flexoelectric energy harvesting performance of self‐powered microbeam devices considering strain gradient and dual‐phase‐lag effects

Abstract

Achieving renewable power for self‐powered electronic devices such as micro/nano‐electro‐mechanical systems is attractive in the fields of energy resources and environment, in this regard, dielectric material structures with excellent energy storage and electromechanical responses have stimulated a surge of research interest. However, in the micro/nanoscale filed, the existing thermo‐electromechanical continuum theories are not capable of fully and effectively characterizing the arising effects, for example, size‐dependent effect and heat lagging effect, etc. To further develop the existing theories, a theoretical prototype for piezo‐flexoelectricity by incorporating strain gradient effect and dual‐phase‐lag heat conduction model is proposed for the first time in this study, and then this proposed model is applied to investigating the energy harvesting performances of a piezo‐flexoelectric micro‐beam under piezoelectric‐thermoelastic coupling. In terms of the differential form of two‐phase elasticity and Hamilton's principle, the governing equations and the boundary conditions for the transverse vibration of a micro‐beam based on the Euler–Bernoulli beam model are derived. By means of the assumed mode method, the influences of the flexoelectricity, the load resistance and the strain gradient on voltage and output power are examined. From the obtained results, it can be aware of that this study not only presents the piezoelectric‐thermoelastic coupling effect of piezo‐flexoelectric configuration in microscale field, but also presents that a piezo‐flexoelectric system at microscale can generate higher power than that reported in previous works. It is hoped that this study could provide some guidelines in designing and optimizing dielectric energy harvesters of micro/nano electronic devices.