dielectric elastomer
Effect of mechanical pre-stretch on the stabilization of dielectric elastomer actuation
A dielectric elastomer is capable of giant electromechanical actuation but fails at breakdown due to instability under certain conditions with a small deformation. By applying a mechanical pre-stretch, one obtains a stabilized large actuation.
NONEQUILIBRIUM THERMODYNAMICS OF DIELECTRIC ELASTOMERS
NONEQUILIBRIUM THERMODYNAMICS OF DIELECTRIC ELASTOMERS
Xuanhe Zhao, Soo Jin Adrian Koh, Zhigang Suo
Theory of dielectric elastomers
In response to a stimulus, a soft material deforms, and the deformation provides a function. We call such a material a soft active material (SAM). This review focuses on one class of soft active materials: dielectric elastomers. Subject to a voltage, a membrane of a dielectric elastomer reduces thickness and expands area, possibly straining over 100%. The phenomenon is being developed as transducers for broad applications, including soft robots, adaptive optics, Braille displays, and electric generators.
Modeling Viscoelastic Dielectrics
Dielectric elastomer, as an important category of electroactive polymers, is known to have viscoelastic properties that strongly affect its dynamic performance and limit its application. Very few models accounting for the effects of both electrostatics and viscoelasticity exist in the literature, and even fewer are capable of making reliable predictions under general loads and constraints. Based on the principals of nonequilibrium thermodynamics, this paper develops a field theory that fully couples the large inelastic deformations and electric fields in deformable dielectrics.
Theory of dielectric elastomers capable of giant deformation of actuation
Theory of dielectric elastomers capable of giant deformation of actuation
Xuanhe Zhao, Zhigang Suo
Physical Review Letters, 104, 178302 (2010)
PhD Winterschool on Dielectric Elastomer Transducers
I’ve just come back from a Winter School on Dielectric Elastomer Transducers, held at Monte Verità, Ascona, Switzerland, 10-16 January 2010. Lectures were given by various people, covering the theory of electromechanical interaction, design of devices, development of materials, and technologies of manufacturing. I was asked to give three lectures on the theory. I attach the slides of my lectures.
Dielectric elastomers of interpenetrating networks
Recent experiments have shown that a voltage can induce a large deformation in an elastomer of interpenetrating networks. We describe a model of interpenetrating networks of long and short chains. As the voltage ramps up, the elastomer may undergo a snap-through instability. The network with long chains fills the space and keeps elastomer compliant at small to modest deformation. The network with short chains acts as a safety net that restrains the elastomer from thinning down excessively, averting electrical breakdown. It appears possible to find a dielectric elastomer capable of giant deformation of actuation. You can read the paper, or take a look at the slides posted here.
Maximal energy that can be converted by a Dielectric Elastomer Generator
Mechanical energy can be converted to electrical energy by using a dielectric elastomer generator. The elastomer is susceptible to various modes of failure, including electrical breakdown, electromechanical instability, loss of tension, and rupture by stretch. The modes of failure define a cycle of maximal energy that can be converted. This cycle is represented on planes of work-conjugate coordinates, and may be used to guide the design of practical cycles.