Fine tuning the electro-mechanical response of dielectric elastomers

TL;DR

This paper introduces a protocol for accurately modeling the electromechanical behavior of dielectric elastomer membranes using experimental stress-stretch and voltage-stretch data, highlighting the conditions for linearity and the interpretation of failure indicators.

Contribution

It presents a novel method to relate electric displacement and field from experimental data, improving understanding of dielectric elastomer responses and failure mechanisms.

Findings

Linear dielectric model is accurate at low-to-moderate electric fields.

Dielectric permittivity can be deduced from experimental data within this range.

Vertical asymptotes in voltage-stretch data indicate electrical breakdown, not strain stiffening.

Abstract

We propose a protocol to model accurately the electromechanical behavior of dielectric elastomer membranes using experimental data of stress-stretch and voltage-stretch tests. We show how the relationship between electric displacement and electric field can be established in a rational manner from this data. Our approach demonstrates that the ideal dielectric model, prescribing linearity in the purely electric constitutive equation, is quite accurate at low-to-moderate values of the electric field and that, in this range, the dielectric permittivity constant of the material can be deduced from stress-stretch and voltage-stretch data. Beyond the linearity range, more refined couplings are required, possibly including a non-additive decomposition of the electro-elastic energy. We also highlight that the presence of vertical asymptotes in voltage-stretch data, often observed in the experiments just prior to failure, should not be associated with strain stiffening effects, but instead with the rapid development of electrical breakdown.