DE (dielectric elastomer) is one of the most promising artificial muscle materials for its large strain over 100% under driving voltage. However, to date, dielectric elastomer actuators (DEAs) are prone to failure due to the temperature-dependent electric breakdown. Previously studies had shown that the
electrical breakdown strength was mainly related to the temperature-dependent elasticity modulus and
the permittivity of dielectric substances. This paper investigated the influence of ambient temperature
on the electric breakdown strength of DE membranes (VHB4910 3M). The electric breakdown experiment of the DE membrane was conducted at different ambient temperatures and pre-stretch levels. The real breakdown strength was obtained by measuring the deformation and the breakdown
voltage simultaneously. Then, we found that with the increase of the environment temperature, the electric breakdown strength decreased obviously. Contrarily, the high pre-stretch level led to the large
electric breakdown strength. What is more, we found that the deformations of DEs were strongly dependent on the ambient temperature.
In this paper, the emerging technology of energy harvesting based on dielectric elastomers (DE), a new type of
functional materials belonging to the family of Electroactive Polymers (EAPs), is presented with emphasis on its
performance characteristics and some key influencing factors. At first, on the basic principle of DE energy harvesting,
the effects of some control parameters are theoretically analyzed under certain mechanical and electrical constraints.
Then, a type of annular DE generator using the commercial elastomers of VHB 4910 (3M, USA), is specially designed
and fabricated. A series of experimental tests for the device’s energy harvesting performance are implemented at
different pre-stretch ratios, stretch amplitudes (displacements), and bias voltages in the constant charge (open-circuit)
condition. The experiment results demonstrate the associated influence laws of the above control parameters on the
performance of the DE generator, and have good consistent with those obtained from the theoretical analysis. This study
is expected to provide a helpful guidance for the design and operation of practical DE energy harvesting devices/systems.
As a new kind of ionic-driven smart materials, ionic polymer metal composite (IPMC ) is normally fabricated by
depositing noble metal (gold, platinum, palladium etc.) on both sides of base membrane (Nafion, Flemion etc.) and
shows large bending deflection under low voltage. In the process of fabricating IPMC, surface roughening of base
membrane has a significant effect on the performance of IPMC. At present, there are many ways to roughen the base
membrane, including physical and chemical ways. In this paper, we analyze the effects of different surface treatment
time by plasma etching on surface resistance and mechanical properties of IPMCs fabricated by the treated base
membranes. Experimental results show that the base membrane treated by plasma etching displays uniform surface
roughness, consequently reducing IPMC’s surface resistance effectively and forming more uniform and homogeneous
external and penetrative electrodes. However, due to the use of reactive gas, the plasma treatment leads to complex
chemical reaction on Nafion surface, changing element composition and material properties and resulting in the
performance degradation of IPMC. And sandblast way should be adopted and improved without any changes on element
and material structure.
A multi-physical model of ionic polymer metal composites (IPMCs) is presented in this paper when they deform under
an applied voltage. It is composed of two parts, which describe the dynamic electro-transport and the large deformation
respectively. The first part describes the ion and water molecule transport, the equations of which are derived using the
thermodynamics of irreversible process. Besides the gradient of the electric potential and the concentration usually
considered in the previous models of IPMCs, the hydrostatic pressure gradient is confirmed to be one of the main factors
induced the mass transport. The second states the eigen strain induced by the redistribution of ion and water molecule
and reveals the stress field from micro to macro scale by the method of micromechanics. The elastic stress balanced with
the eigen-stress including the hydrostatic pressure can influence the distribution of ion and water molecule reversely. To
explore the reasonable mechanisms of the relaxation phenomena, various kinds of eigen-stresses are discussed here and
preliminary numerical results evaluating deformation are given based on the classical Na+ Nafion type IPMC. It's
obtained that the osmotic pressure is an indispensable eigen-stress to explain the complicated deformation.
The electromechanical behavior of dielectric elastomer is strongly affected by the temperature. Very few models
accounting for the effects of temperature exist in the literature. A recent experiment showed that the variation of
dielectric constant of the most widely used dielectric elastomer (VHB 4910, 3M) according to temperature is relatively
significant. In this paper, we develop a thermodynamic model to study the influence of temperature on the instability in
dielectric elastomer by involving deformation and temperature-dependent dielectric constant. The results indicate that
the increase of temperature could improve the actuation stress and the electromechanical instability of the elastomer.
The electrode of Ionic polymer-metal composites (IPMCs) is the key to understand their working mechanisms and
mechano-electrical properties; however, there is little experimental report on the electrode morphologies and their
forming mechanisms. In this paper, several typical IPMC samples with different electrode morphologies are fabricated
by combining various process steps. The influence of the process steps, such as roughing treatment, immersing reduction
and chemical plating, on the electrode surface and cross-section morphologies is investigated by SEM study, where the
reaction principles are employed to explain that how the metal particles generate and grow at different directions of the
electrode. The current and deformation responses of the samples are measured at the present of a voltage to characterize
the mechano-electrical properties. Then it is concluded that immersing reduction is only suitable as a pre-deposition
process step, and chemical plating is necessary for IPMC with desirable performance.
A new method of initialization about the real-time GPS attitude determination system is presented. The combination solutions of the dualistic, non-linear equations and the ambiguity function method promote the computation efficiency of the initialization. The paper discusses the ambiguity function method and describes the observation equation in terms of geometry. The analytical solution of the dual non-linear coupled equation is given, and the real-time data are processed. As a result, compared with the normal method, the new method is more effective and economical.