Dielectric elastomer(DE) could be used in generator design and fabrication, which has been verified by experiments. The
function principle of DE generator is contrary to that of DE actuator. By imposing a low voltage to the dielectric
elastomer membrane, electric charges are accumulated on the two surfaces. Then we apply mechanical force to the sides
of the membrane to produce pre-stretch, and the thickness of the membrane becomes thinner and the capacitance
increases, where mechanical energy is converted to elastic energy. After the mechanical force being withdrawn, because
of elasticity, the thickness of membrane increases while the capacitance decreases, and elastic energy is converted to
electrical energy. This is a work cycle of conversion from elastic to electric energy. Researchers have always been
expecting to find a model that can well predict and evaluate the performance of dielectric elastomer generator. Suo et al.
proposed the typical failure model of neo-Hooken type dielectric elastomer generator and calculates the maximal energy
converted in a mechanical and electrical cycle. In this paper, we demonstrate the area of allowable states of various
Mooney-Rivlin type dielectric elastomer generators, which can be employed to direct the design and fabrication of
Mooney-Rivlin silicone generator, and the results coincide with Suo's theory.
By adding randomly distributed short fiber into a shape memory polymer (SMP) matrix, both the mechanical properties
and the shape memory behavior are improved significantly, overcoming some traditional defects of SMP composite
reinforced by long fiber and particles. In this paper, the short fiber reinforced SMP composite are developed for the
improvement of the mechanical and thermal properties of styrene-based SMP bulk. The specimens with different
chopped fiber weight fractions are prepared, and then their mechanical behavior and electrical properties are
investigated. As a result, the resistance against mechanical and thermal mechanical loads in the developed materials
increases due to the role of reinforcement fiber. For the conducting composite filled with short carbon fiber, not only the
actuation of SMP composite can be driven by low voltage, but also its tensile, bending strength, glass transition temperature, storage modulus and thermal conductivity increase by a factor of filler content of carbon fiber increasing. The results show meaningful guidance for further design and the performance evaluation of such composite materials.
Silicone rubber is a common dielectric elastomer material. Actuators made from it show excellent activate properties
including very large strains (up to 380%), high elastic energy densities (up to 3.4 J/g), high efficiency, high responsive
speed, good reliability and durability, etc. When voltage is applied on the compliant electrodes of the dielectric
elastomers silicone rubber, the polymer shrinks along the electric field and expands in the transverse plane. In this paper,
a theoretical analysis is performed on the coupling effects of the mechanical and electric fields. A nonlinear field theory
of deformable dielectrics and hyperelastic theory are adopted to analyze the electromechanical field behavior of these
actuators. Applied elastic strain energy function is obtained from the representative Yeoh model. The electric energy
function involves invariant and variable dielectric constant respectively. Then deduce the constitutive relation for the
dielectric elastomer film actuator based on the selected function. Also the mechanical behavior of the dielectric
elastomer silicone rubber undergoing large free deformation is studied. The constitutive modules of dielectric elastomer
composite under free deformation and restrained deformation are derived. The Barium Titanate (BaTiO3) with high
permittivity was incorporated into the raw silicone to fabricate a new dielectric elastomer, the experimental results that
the elastic modulus and dielectric constant were significantly improved. Finally the Yeoh model was developed to
characterize the elastic behavior of the new dielectric elastomer. The constitutive modules of dielectric elastomer
composite under free deformation and restrained deformation are derived. This is a promising analysis method for the
study of the coupled fields and mechanical properties of the dielectric film actuator.
In this paper, a novel kind of deployable morphing wing base on shape memory polymer (SMP) composite is designed
and tested. While the deployment of the morphing wing still relies on the mechanisms to ensure the recovery force and
the stability performance, the deploying process tends to be more steady and accurate by the application of SMP
composite, which overcomes the inherent drawbacks of the traditional one, such as harmful impact to the flight balance,
less accuracy during the deployment and complex mechanical masses. On the other hand, SMP composite is also
designed as the wing's filler. During its shape recovery process, SMP composite stuffed in the wing helps to form an
aerofoil for the wing and withstand the aerodynamic loads, leading to the compressed aerofoil recovering its original
shape. To demonstrate the feasibility and the controllability of the designed deployable morphing wing, primary tests are
also conducted, including the deploying speed of the morphing wing and SMP filler as the main testing aspects. Finally,
Wing's deformation under the air loads is also analyzed by using the finite element method to validate the flight stability.
Dielectric elastomers have received a great deal of attention recently for effectively transforming electrical energy to
mechanical work. Their large strains and conformability make them enticing materials which can be applied in many
domains: biomimetics, aerospace, mechanics, medicals, etc. In order to maximize actuator performance, the dielectric
elastomer actuators should have a high dielectric constant and high dielectric breakdown strength. Here we have
investigated the increase in permittivity of a commercial silicone elastomer by the addition of carbon nanotube. The
percolation threshold of the composites is obtained to be low. Experimental results suggest that for the case of
conductive filler particle-elastomer matrix interaction, actuation strain increases with increasing carbon nanotube content.
A new concept of a morphing wing based on shape memory polymer (SMP) and its reinforced composite is proposed in
this paper. SMP used in this study is a thermoset styrene-based resin in contrast to normal thermoplastic SMP. In our
design, the wing winded on the airframe can be deployed during heating, which provides main lift for a morphing aircraft
to realize stable flight. Aerodynamic characteristics of the deployed morphing wing are calculated by using CFD
software. The static deformation of the wing under the air loads is also analyzed by using the finite element method. The
results show that the used SMP material can provide enough strength and stiffness for the application.
Dielectric elastomers (DE) are the most promising electroactive polymer materials capable of being applied in smart actuators. When the DE film sandwiched between two compliant electrodes is applied high electric field, due to the electrostatic force between two electrodes, the film expands in-plane and contracts out-of-plane such that its thickness becomes thinner. The thinner thickness results in higher electric field which inversely squeezes the film again. This positive feedback induces a mode of instability, known as electromechanical instability or pull-in instability. When the electric field exceeds certain critical value, the DE film collapses. In this paper, the elastic strain energy function with two material constants is applied to analyze the stability of dielectric elastomers, which facilitates to understand fully Suo's nonlinear theory. The results verify again the truth of this theory and exploit larger application spectrum. The method is capable of analyzing the stability of different dielectric materials with different values of k and the result can be useful on design of the dielectric elastomer actuator.
A new concept of a morphing wing based on shape memory polymer (SMP) and its reinforced composites is proposed in
this paper. SMP used in this study is a thermoset styrene-based resin in contrast to normal thermoplastic SMP. During
heating, the wing curled on the aircraft can be deployed, providing main lift for a morphing aircraft to realize the stable
flight. Aerodynamic characteristics of the deployed morphing wing are calculated by using CFD software. The static
deformation of the wing under the air loads is also analyzed by using the finite element method. The results show that the
used SMP material can provide enough strength and stiffness for the application. Finally, preliminary testing is
conducted to investigate the recovery performances of SMP and its reinforced composites. During the test, the
deployment and the wind-resistant ability of the morphing wing are dramatically improved by adding reinforced phase to
the SMP.
Dielectric elastomers (Des) are a type of EAPs with unique electrical properties and mechanical properties: high
actuation strains and stresses, fast response times, high efficiency, stability, reliability and durability. The excellent
figures of merit possessed by dielectric elastomers make them the most performing materials which can be applied in
many domains: biomimetics, aerospace, mechanics, medicals, etc. In this paper, we present a kind of electroactive
polymer composites based on silicone Dielectric elastomers with a high dielectric constant. Novel high DEs could be
realized by means of a composite approach. By filling an ordinary elastomer (e.g. silicone) with a component of
functional ceramic filler having a greater dielectric permittivity, it is possible to obtain a resulting composite showing
the fruitful combination of the matrix's advantageous elasticity and the filler's high permittivity. Here we add the
ferroelectric relaxor ceramics (mainly BaTiO3) which has high dielectric constant (>3000) to the conventional silicone
Dielectric elastomers, to get the dielectric elastomer which can exhibit high elastic energy densities induced by an
electric field of about 15 MV/m. Tests of the physical and chemical properties of the dielectric elastomers are conducted,
which verify our supposes and offer the experimental data supporting further researches.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.