Dielectric elastomer film actuators: characterization, experiment and analysis**This article was originally submitted for the special section ‘Smart Composite Materials:Selected Papers from the International Conference on Multifunctional Materials andStructures (MFMS 08) (Hong Kong, 28–31 July 2008)’, Smart Materials and Structures,volume 18, issue 7.

Abstract

Silicone is a common dielectric elastomer material. Actuators made from it show excellentactivation properties including large strains (up to 380%), high energy densities (up to3.4 J g−1), high efficiency, high responsive speed, good reliability and durability, etc. When a voltageis applied on the compliant electrodes of the dielectric elastomers, the polymer shrinksalong the electric field and expands in the transverse plane. In this paper, a siliconedielectric elastomer is synthesized and the area strains are tested under different electricfields. Pre-strain and a certain driving electric field are applied to the film andthe induced large strain by the Maxwell stress is measured. Barium titanate (BaTiO3) was incorporated into the silicone to fabricate a new dielectric elastomer: theexperimental results show that the elastic modulus and dielectric constant weresignificantly improved. The experimental results coincide well with those of finite elementanalysis at a large deformation. Also, a theoretical analysis is performed on the couplingeffects of the mechanical and electric fields. A nonlinear field theory of deformabledielectrics and hyperelastic theory are adopted to analyze the electromechanical fieldbehavior of these actuators. Also the mechanical behavior of the dielectric elastomerundergoing large free deformation is studied. Finally, the constitutive model of a dielectricelastomer composite under free deformation and restrained deformation is derived.