Dielectric elastomer actuators (original) (raw)
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Smart Structures and Materials 2006: Electroactive Polymer Actuators and Devices (EAPAD), 2006
In this work the electromechanical performance of planar, single-layered dielectric elastomer (DE) actuators was investigated. The mechanical power density and the overall electromechanical efficiency of DE stripe actuators under continuous activation cycles were examined. The viscoelastic behavior of the dielectric film was modeled with a threedimensionally coupled spring-damper framework. This film model was fitted to the mechanical behavior of the acrylic film VHB 4910 (3M) evaluated in a combination of a uniaxial loading test with holding time and subsequent unloading. In addition the quasielastic film model was derived in order to evaluate the quasistatic behavior of DE actuators under activation. For the simulation of DE actuators the boundary conditions of the film model were accordingly adapted. By embedding the actuator into an appropriate electrical circuit electrodynamic effects were incorporated as well. The quasielastic model of a planar DE actuator with free boundary conditions predicted a stable deformation state for activation with constant charge. For activation with constant electrical voltage, however, the model showed a stable and an instable equilibrium state. For activation voltages beyond a critical voltage the film collapses in thickness direction due to the electrostatic forces (Maxwell stresses). A biaxially prestrained stripe actuator was described with the viscoelastic film model. The stripe actuator was cyclically activated and cyclically elongated with a phase shift (displacement-controlled). A qualitative parameter study showed that the overall electromechanical efficiency as well as the specific power density of such DE actuators strongly depends on the electrical activation and the external mechanical loading.
Finite element modelling of dielectric elastomer minimum energy structures
Applied Physics A-materials Science & Processing, 2009
This paper presents an experimentally validated finite element model suitable for simulating the quasi-static behaviour of Dielectric Elastomer Minimum Energy Structure(s) (DEMES). A DEMES consists of a pre-stretched Dielectric Elastomer Actuator (DEA) adhered to a thin, flexible frame. The tension in the stretched membrane causes the frame to curl up, and when a voltage is applied, the frame returns to its initial planar state thus forming a useful bending actuator. The simulation method presented here incorporates a novel strain energy function suitable for simulating general DEA actuator elements. When compared against blocked force data from our previous work, the new model provides a good fit with an order of magnitude reduction in computational time. Furthermore, the model accurately matched experimental data on the free displacement of DEMES formed with non-equibiaxially pre-stretched VHB4905 membranes driven by 2500 V. Non-equibiaxially pre-stretching the membranes allowed control of effective frame stiffness and bending moment, this was exploited by using the model to optimise stroke at 2500 V in a hypothetical case study. Dielectric constant measurements for non-equibiaxially stretched VHB4905 are also presented.
Electroactive Polymer Actuators and Devices (EAPAD) 2013, 2013
Dielectric elastomer actuators are considered as promising candidates for robotic elements. To this end, planar dielectric elastomer actuators (p-DEAs) and dielectric elastomer minimum energy structures (DEMES) are applicable. However, the knowledge of their electrical and mechanical characteristics is of major importance for engineering tasks. Therefore we study p-DEAs and DEMES by impedance spectroscopy (IS) and dynamic capacitive extensometry (DCE). We vary the boundary conditions with regard to p-DEAs (free and fixed boundaries) and fabricate various DEMES with one angular degree of freedom. A mixture of carbon black particles and silicone oil serves as compliant electrodes. We present equivalent circuit models of the actuators based on impedance spectroscopy data, the frequency ranges in which they are applicable and effects of aging on the equivalent circuit models. By DCE the electrical characteristics of dielectric elastomer actuators are monitored in situ during dynamic high voltage actuation. These electrical characteristics of the dielectric elastomer actuators such as p-DEAs and DEMES can be related to their transient stretch in response to high voltage driving signals. We study the viscoelastic response of the actuators to square driving signals of different magnitudes; furthermore we monitor the state of the compliant electrodes. By means of the DCE measurement data and the impedance spectra the p-DEAs and DEMES can be compared. Downloaded From: http://proceedings.spiedigitallibrary.org/ on 07/29/2013 Terms of Use: http://spiedl.org/terms Proc. of SPIE Vol. 8687 86871G-2 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 07/29/2013 Terms of Use: http://spiedl.org/terms Proc. of SPIE Vol. 8687 86871G-3 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 07/29/2013 Terms of Use: http://spiedl.org/terms
El-Cezeri Fen ve Mühendislik Dergisi, 2021
Dielectric Elastomer Actuator (DEA) consists of a thin dielectric elastomer membrane sandwiched between two electrode layers. When low current high voltage is applied to the two conductive layers, opposite loads occur on the surface which tends to pull one another. This voltage application causes thinning in width and expansion in surface area. DEAs are the favorite subject of research due to their low-cost advantages, fast response, high energy density, wide deformation, and softness. Due to the rigidity of the electric motors and the metal components of the robot, soft-acting robots using DEA are preferred to perform complex tasks instead of conventional robots. Robots with DEA have higher flexibility and better adaptability. Therefore, soft robots are popular topic in robotics research. DEAs are the best candidate materials for next-generation soft robot actuators and artificial muscles. In this study, simulation of the robotic systems has been realized by using DEAs calculation methods. Simulation results were compared with the data obtained from the application. This study will be the source of future studies on the subject. In the simulation, Matlab 2016 student and Labview Home and Students programs were used.
On the performance mechanisms of Dielectric Elastomer Actuators
Sensors and Actuators A: Physical, 2007
Dielectric Elastomer Actuators (DEAs) show promise for robotics and mechatronics applications. They are lightweight, low costs, and have shown good performance in laboratory demonstration. However, these actuators have not been widely applied commercially after more than ten years of development. One reason is that the mechanisms governing their performance are not completely understood. Hence designing practical actuators is difficult. This paper has the objective of understanding the dominant performance mechanisms of DEAs. To do so, an experimental characterization of actuator performance is conducted in terms of force, power, current consumption, work output, and efficiency. Key performance mechanisms of viscoelasticity and current leakage are identified from experimental observations and analytical models are developed. The models explain well the experimental observations and should aid designers in selecting applications that are appropriate for DEAs as well as designing effective DEAs.
Dynamic response of dielectric elastomer under electrical loading condition
The present paper is concerned with the analytical modeling for a dielectric elastomeric actuator under the electrical loading condition. A common usage of a dielectric elastomeric actuator is to realize simultaneous displacements when an electrical loading is applied. These simultaneous displacements are advantageous in the field of robotics and smart manufacturing industries. A fundamental deformation approach is presented to model the dynamic response of a homogeneously deformed dielectric elastomer with the application of electrical loading condition. The dynamic equation of motion is formulated through the standard Euler-Lagrange method. The numerical results obtained from the developed equation of motion are discussed in comparison with the similar results presented in the literature to show the vibration and oscillation behaviour of the dielectric elastomer.
2021
The present study deals with the buckling phenomenon modeling in a dome-shaped dielectric elastomeric (DE) actuator used in different aerodynamic and fluid power system applications. The DE actuator is a circular membrane type of actuator, which shows a large out-of-plane axial-symmetric deformation with an electrically induced loading condition. A classical continuum mechanics-based analytical model is developed to predict the electrically induced buckling deformation in the actuator. A detailed parametric study has been performed to see the influence of standard Neo-Hookean and Mooney-Rivlin types of potential energies on the geometrical and physical parameters. The findings show that the present model successfully links the sensitivity of different potential energies concerning the actuator’s initial dome height and radius.
2015
Dielectric elastomers (DEs) are being developed as artificial muscles for diverse applications, including soft machines, adaptive optics, haptic surfaces, micro air vehicles, strain sensors, fluidic micro-pumps and energy harvesting (Carpi et al., 2008; Carpi et al., 2010; Brochu & Pei, 2010; Kornbluh et al., 2012). They are superior to piezoelectric, shape memory alloys and electrostrictive materials in terms of large voltage-induced deformation, high energy density, fast response, quiet operation, light weight, and low cost. To increase the electromechanical performance, the elastomers are pre-stretched with an in-plane area stretch up to 36. These large deformations may lead to rupture and thus impair the mechanical integrity of the devices. Further development of dielectric elastomer transducers demands accurate and efficient computational methods (Wissler, 2007; Lochmatter, 2007). The transducers involve nonlinear electromechanical coupling, and are often hybrid structures of s...
Construction Techniques and Statistical Analysis of Dielectric Elastomer Actuators
2018
In this study, a series of experiments were conducted to investigate and improve upon existing construction methods of dielectric elastomer actuators (DEAs). First, a proof of concept was built, which utilized a DEA as an active diaphragm to reproduce sound. Next, two electrode sizes and construction methods were compared via statistical analysis of electrode strain. In an attempt to develop an easier and more efficacious electrode construction method, the substance used for electrodes was then dissolved in six solvents. A commercially available graphite spray was compared against the solutions and determined to be the most promising on the basis of measured surface conductivity and observed particle dispersion. Finally, an actuator was tested with graphite spray electrodes; it was discovered that the spray hardens when dried and was thus not able to produce in-plane deformation.