A Nonlinear Model for Dielectric Elastomer Membranes

2005 ◽  
Vol 72 (6) ◽  
pp. 899-906 ◽  
Author(s):  
Nakhiah Goulbourne ◽  
Eric Mockensturm ◽  
Mary Frecker
Keyword(s):  
Large Deformations ◽  
Mathematical Formulation ◽  
Dielectric Elastomer ◽  
External Pressure ◽  
Membrane Area ◽  
System Parameters ◽  
Geometrical Nonlinearities ◽  
Dielectric Elastomer Actuators ◽  
Materials Used ◽  
Dielectric Elastomer Membrane

The material and geometrical nonlinearities of novel dielectric elastomer actuators make them more difficult to model than linear materials used in traditional actuators. To accurately model dielectric elastomers, a comprehensive mathematical formulation that incorporates large deformations, material nonlinearity, and electrical effects is derived using Maxwell-Faraday electrostatics and nonlinear elasticity. The analytical model is used to numerically solve for the resultant behavior of an inflatable dielectric elastomer membrane, subject to changes in various system parameters such as prestrain, external pressure, applied voltage, and the percentage electroded membrane area. The model can be used to predict acceptable ranges of motion for prescribed system specifications. The predicted trends are qualitatively supported by experimental work on fluid pumps [A. Tews, K. Pope, and A. Snyder, Proceedings SPIE, 2003)]. For a potential cardiac pump application, it is envisioned that the active dielectric elastomer membrane will function as the motive element of the device.

Energy Optimal Control of Dielectric Elastomer Actuators via Adaptive Dynamic Programming

2019 ◽  
Author(s):  
Paolo Roberto Massenio ◽  
David Naso ◽  
Gianluca Rizzello
Keyword(s):  
Optimal Control ◽  
Dynamic Programming ◽  
Dielectric Elastomer ◽  
Adaptive Dynamic Programming ◽  
Set Point ◽  
Adaptive Dynamic ◽  
Strongly Nonlinear ◽  
Dielectric Elastomer Actuators ◽  
Control Scheme ◽  
Dielectric Elastomer Membrane

Abstract This paper presents an optimal motion control scheme for a mechatronic actuator based on a dielectric elastomer membrane transducer. The optimal control problem is formulated such that a desired position set-point is reached with minimum amount of driving energy, characterized via an accurate physical model of the device. Since the considered actuator is strongly nonlinear, an approximated approach is required to practically address the design of the control system. In this work, an Adaptive Dynamic Programming based algorithm is proposed, capable of minimizing a cost function related to the energy consumption of the considered system. Simulation results are presented in order to assess the effectiveness of the proposed method, for different set-point regulation scenarios.

High-frequency oscillations of low-voltage dielectric elastomer actuators

2021 ◽  
Author(s):  
Ardi Wiranata ◽  
Makoto Kanno ◽  
Naoki Chiya ◽  
Hozuma Okabe ◽  
Tatsuhiro Horii ◽  
...  
Keyword(s):  
High Frequency ◽  
Low Voltage ◽  
Electric Circuit ◽  
Dielectric Elastomer ◽  
Membrane Thickness ◽  
Frequency Range ◽  
Dielectric Elastomer Actuators ◽  
Roll To Roll ◽  
High Frequency Oscillations ◽  
Dielectric Elastomer Membrane

Abstract To increase safety and reduce the electric circuit cost, Dielectric elastomer actuators (DEAs) must operate below the kV range. The simplest strategy to reduce the voltage operation is to decrease the dielectric elastomer membrane thickness. This research aims to demonstrate DEAs with a nanometric uniform thickness that can operate at a low voltage (below 70 V) and a high frequency. We use the roll-to-roll process to fabricate a 600-nm-thick stretchable PDMS (polydimethylsiloxane) nanosheet and a 200-nm-thick conductive nanosheet. These nanosheet-DEAs are tested in high-frequency operations of DC voltage below 70 V and in a frequency range of 1–30 kHz.

scholarly journals A dynamic electrically driven soft valve for control of soft hydraulic actuators

2021 ◽  
Vol 118 (34) ◽  
pp. e2103198118
Author(s):  
Siyi Xu ◽  
Yufeng Chen ◽  
Nak-seung P. Hyun ◽  
Kaitlyn P. Becker ◽  
Robert J. Wood
Keyword(s):  
Power Density ◽  
Flow Rate ◽  
Dielectric Elastomer ◽  
External Pressure ◽  
Operating Conditions ◽  
Effective Control ◽  
Hydraulic Actuators ◽  
Dielectric Elastomer Actuators ◽  
Multiple Actuators ◽  
Density Dynamic

Regulation systems for fluid-driven soft robots predominantly consist of inflexible and bulky components. These rigid structures considerably limit the adaptability and mobility of these robots. Soft valves in various forms for fluidic actuators have been developed, primarily fluidically or electrically driven. However, fluidic soft valves require external pressure sources that limit robot locomotion. State-of-the-art electrostatic valves are unable to modulate pressure beyond 3.5 kPa with a sufficient flow rate (>6 mL⋅min−1). In this work, we present an electrically powered soft valve for hydraulic actuators with mesoscale channels based on a different class of ultrahigh-power density dynamic dielectric elastomer actuators. The dynamic dielectric elastomer actuators (DEAs) are actuated at 500 Hz or above. These DEAs generate 300% higher blocked force compared with the dynamic DEAs in previous works and their loaded power density reaches 290 W⋅kg−1 at operating conditions. The soft valves are developed with compact (7 mm tall) and lightweight (0.35 g) dynamic DEAs, and they allow effective control of up to 51 kPa of pressure and a 40 mL⋅min−1 flow rate with a response time less than 0.1 s. The valves can also tune flow rates based on their driving voltages. Using the DEA soft valves, we demonstrate control of hydraulic actuators of different volumes and achieve independent control of multiple actuators powered by a single pressure source. This compact and lightweight DEA valve is capable of unprecedented electrical control of hydraulic actuators, showing the potential for future onboard motion control of soft fluid-driven robots.

scholarly journals Mechanical behavior of a circular dielectric elastomer membrane under out-of-plane deformation

2020 ◽  
Vol 37 ◽  
pp. 184-191
Author(s):  
J W Zhang ◽  
J W Chen ◽  
Z Q Ren
Keyword(s):  
Mechanical Behavior ◽  
System Analysis ◽  
Plane Deformation ◽  
Dielectric Elastomer ◽  
Electrical Parameters ◽  
Dielectric Elastomer Actuators ◽  
Out Of Plane ◽  
Gent Model ◽  
Dielectric Elastomer Membrane ◽  
Theoretical Results

Abstract The mechanical behavior of a circular dielectric elastomer membrane (DEM) under the contact of a rigid ball is studied in this paper. The out-of-plane deformation of the DEM is unfolded to an equivalent in-plane deformation, and the mechanical behavior is further studied through the Helmholtz free energy theory and the Gent model. The theoretical results obtained from the proposed analysis approach are validated through the out-of-plane deformation experiments, and the influence of the DEM's thickness on the mechanical behavior is revealed and explained. Furthermore, the influences of some key dimensional, dynamical and electrical parameters on the DEM's mechanical behavior are investigated and discussed. The research results are helpful for the system analysis of dielectric elastomer actuators and dielectric elastomer generators with out-of-plane deformations.

scholarly journals A broadbanded pressure differential wave energy converter based on dielectric elastomer generators

2021 ◽  
Author(s):  
Michele Righi ◽  
Giacomo Moretti ◽  
David Forehand ◽  
Lorenzo Agostini ◽  
Rocco Vertechy ◽  
...  
Keyword(s):  
Wave Energy ◽  
Large Deformations ◽  
Dielectric Elastomer ◽  
Wave Energy Converter ◽  
Pressure Differential ◽  
Design Stage ◽  
Small Scale ◽  
Energy Converter ◽  
Wide Range ◽  
The Waves

AbstractDielectric elastomer generators (DEGs) are a promising option for the implementation of affordable and reliable sea wave energy converters (WECs), as they show considerable promise in replacing expensive and inefficient power take-off systems with cheap direct-drive generators. This paper introduces a concept of a pressure differential wave energy converter, equipped with a DEG power take-off operating in direct contact with sea water. The device consists of a closed submerged air chamber, with a fluid-directing duct and a deformable DEG power take-off mounted on its top surface. The DEG is cyclically deformed by wave-induced pressure, thus acting both as the power take-off and as a deformable interface with the waves. This layout allows the partial balancing of the stiffness due to the DEG’s elasticity with the negative hydrostatic stiffness contribution associated with the displacement of the water column on top of the DEG. This feature makes it possible to design devices in which the DEG exhibits large deformations over a wide range of excitation frequencies, potentially achieving large power capture in a wide range of sea states. We propose a modelling approach for the system that relies on potential-flow theory and electroelasticity theory. This model makes it possible to predict the system dynamic response in different operational conditions and it is computationally efficient to perform iterative and repeated simulations, which are required at the design stage of a new WEC. We performed tests on a small-scale prototype in a wave tank with the aim of investigating the fluid–structure interaction between the DEG membrane and the waves in dynamical conditions and validating the numerical model. The experimental results proved that the device exhibits large deformations of the DEG power take-off over a broad range of monochromatic and panchromatic sea states. The proposed model demonstrates good agreement with the experimental data, hence proving its suitability and effectiveness as a design and prediction tool.

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