Modeling electromechanical properties of layered electrets: Application of the finite-element method

TL;DR

This paper models the electromechanical behavior of layered electrets using finite-element simulations, exploring how material properties and charge configurations influence piezoelectricity.

Contribution

It introduces a finite-element modeling approach for layered electrets, analyzing the effects of material parameters and charge types on electromechanical responses.

Findings

Piezoelectric coefficients depend strongly on elastic moduli in bipolar charge systems.

Mono-polar charge systems show negligible piezoelectric effects.

Non-uniform surface charges and low Poisson's ratio enhance piezoelectricity.

Abstract

We present calculations on the deformation of two- and three-layer electret systems. The electrical field is coupled with the stress-strain equations by means of the Maxwell stress tensor. In the simulations, two-phase systems are considered, and intrinsic relative dielectric permittivity and Young's modulus of the phases are altered. The numerically calculated electro-mechanical activity is compared to an analytical expression. Simulations are performed on two- and three-layer systems. Various parameters in the model are systematically varied and their influence on the resulting piezoelectricity is estimated. In three-layer systems with bipolar charge, the piezoelectric coefficients exhibit a strong dependence on the elastic moduli of the phases. However, with mono-polar charge, there is no significant piezoelectric effect. A two-dimensional simulation illustrated that higher piezoelectricity coefficients can be obtained for non-uniform surface charges and low Poisson's ratio of phases. Irregular structures considered exhibit low piezoelectric activity compared to two-layer structures.