Instability in Nonlinear Oscillation of Dielectric Elastomers

2015 ◽  
Vol 82 (6) ◽  
Author(s):  
Jian Zhu
Keyword(s):  
Nonlinear Oscillation ◽  
Electromechanical Coupling ◽  
Haptic Feedback ◽  
Dynamic Instability ◽  
Dielectric Elastomer ◽  
Dielectric Elastomers ◽  
Critical Amplitude ◽  
Dielectric Elastomer Actuators ◽  
Coupling Dynamic ◽  
Static Instability

A membrane of a dielectric elastomer oscillates when subject to AC voltage. Its oscillation is nonlinear due to large deformation and nonlinear electromechanical coupling. Dynamic instability in dielectric elastomers—the oscillation with an unbounded amplitude—is investigated in this paper. The critical amplitude of AC voltage for dynamic instability varies with the frequency of AC voltage and reaches a valley when the superharmonic, harmonic, or subharmonic resonance is excited. Prestretches can improve dielectric elastomer actuators' capabilities to resist dynamic instability. The critical deformation at the onset of dynamic instability can be much larger than that at the onset of static instability. Oscillation of dielectric elastomers can be used for applications, such as vibration shakers for haptic feedback, soft loudspeakers, soft motors, and soft pumps. We hope that the current analyses can improve the understanding of dynamic behavior of dielectric elastomers and enhance their stability and reliability.

An Energy-Based Approach to Extract the Dynamic Instability Parameters of Dielectric Elastomer Actuators

2014 ◽  
Vol 81 (9) ◽  
Author(s):  
M. M. Joglekar
Keyword(s):  
Electric Field ◽  
Dynamic Instability ◽  
Time History ◽  
Material Model ◽  
Dielectric Elastomer ◽  
Step Voltage ◽  
Dielectric Elastomer Actuators ◽  
Time History Response ◽  
Maximum Stretch ◽  
Static Instability

An energy-based approach is presented to extract the thresholds on the transient dynamic response of step voltage driven dielectric elastomer actuators (DEAs). The proposed approach relies on establishing the energy balance at the point of maximum stretch in an oscillation cycle followed by the application of an instability condition to extract the dynamic instability parameters. Explicit expressions are developed for the critical values of maximum stretch and the corresponding nominal electric field, thus circumventing the need to perform iterative time-integrations of the equation of motion. The underlying principles of the approach are enunciated for the neo-Hookean material model and further extended to analyze relatively complex multiparameter hyperelastic models (Mooney–Rivlin and Ogden) that are employed prevalently for investigating the behavior of DEAs. The dynamic instability parameters predicted using the energy method are validated by examining the time-history response of the actuator in the vicinity of the dynamic instability. The development of dynamic instability parameters is complemented by energy-based extraction of static instability parameters to facilitate a quick comparison between the two. It is inferred quantitatively that the nominal electric field sufficient to cause the dynamic instability and the corresponding thickness stretch is lower than those corresponding to the static instability. A set of representative case studies for multiparameter material models is presented at the end, which can be used as an input for further experimental corroboration. The results of the present investigation can find their potential use in the design of DEAs subjected to transient loading.

Dynamic Modeling and Experimental Validation of an Annular Dielectric Elastomer Actuator With a Biasing Mass

2015 ◽  
Vol 137 (1) ◽  
Author(s):  
Gianluca Rizzello ◽  
Micah Hodgins ◽  
David Naso ◽  
Alexander York ◽  
Stefan Seelecke
Keyword(s):  
Electromechanical Coupling ◽  
Dielectric Elastomer ◽  
Reference Case ◽  
Dielectric Elastomer Actuators ◽  
Annular Geometry ◽  
Standard Linear ◽  
Dynamic Loading Conditions ◽  
Actuator Design ◽  
Static And Dynamic Loading ◽  
Relevant Range

This paper presents a model for the electromechanically coupled dynamic behavior of dielectric elastomer actuators (DEA). The main goal is to develop a lumped, dynamic model which can be used for the optimization of actuator design in specific applications as well as for the synthesis of high precision, model-based feedback control algorithms. A mass-biased membrane actuator with an annular geometry is chosen as a reference case to introduce the modeling concept. The mechanical model extends standard linear visco-elasticity through the introduction of a nonlinear hyperelastic Ogden element. Electromechanical coupling is implemented through the Maxwell stress concept. The DEA model is then experimentally calibrated and validated for both quasi static and dynamic loading conditions. It can be shown that both mechanical preloading and electric actuation can be reproduced over a relevant range of masses and frequencies.

scholarly journals Linear-Quadratic Regulator for Control of Multi-Wall Carbon Nanotube/Polydimethylsiloxane Based Conical Dielectric Elastomer Actuators

Actuators ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 18
Author(s):  
Titus Mulembo ◽  
Waweru Njeri ◽  
Gakuji Nagai ◽  
Hirohisa Tamagawa ◽  
Keishi Naito ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Rise Time ◽  
Electromechanical Coupling ◽  
Linear Quadratic Regulator ◽  
Fast Response ◽  
Dielectric Elastomer ◽  
Soft Robotics ◽  
Artificial Muscles ◽  
Linear Quadratic ◽  
Dielectric Elastomer Actuators

Conventional rigid actuators, such as DC servo motors, face challenges in utilizing them in artificial muscles and soft robotics. Dielectric elastomer actuators (DEAs) overcome all these limitations, as they exhibit complex and fast motions, quietness, lightness, and softness. Recently, there has been much focus on studies of the DEAs material’s non-linearity, the non-linear electromechanical coupling, and viscoelastic behavior of VHB and silicone-based conical DEAs having compliant electrodes that are based on graphite powder and carbon grease. However, the mitigation of overshoot that arises from fast response conical DEAs made with solid electrodes has not received much research focus. In this paper, we fabricated a conical configuration of multi-walled carbon nanotube/polydimethylsiloxane (MWCNT/PDMS) based DEAs with a rise time of 10 ms, and 50% peak overshoot. We developed a full feedback state-based linear-quadratic regulator (LQR) having Luenberger observer to mitigate the DEAs overshoot in both the voltage ON and OFF instances. The cone DEA’s model was identified and a stable and well-fitting transfer function with a fit of 94% was obtained. Optimal parameters Q = 70,000, R = 0.1, and Q = 7000, R = 0.01 resulted in the DEA response having a rise time value of 20 ms with zero overshoot, in both simulations and experiments. The LQR approach can be useful for the control of fast response DEAs and this would expand the potential use of the DEAs as artificial muscles in soft robotics.

scholarly journals A Simple Dynamic Characterization Method for Thin Stacked Dielectric Elastomer Actuators by Suspending a Weight in Air and Electrical Excitation

Actuators ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 40
Author(s):  
Kentaro Takagi ◽  
Yuya Kitazaki ◽  
Kota Kondo
Keyword(s):  
Elastic Modulus ◽  
Forced Vibration ◽  
Electromechanical Coupling ◽  
Great Difficulty ◽  
Dielectric Elastomer ◽  
Local Deformation ◽  
Dynamic Elastic Modulus ◽  
Electrical Excitation ◽  
Dynamic Characterization ◽  
Dielectric Elastomer Actuators

This paper proposes a simple but effective method for characterizing dielectric elastomer actuators (DEAs), especially for thin stacked DEAs, which are promising for haptic devices but which measure the dynamic elastic modulus with great difficulty. The difficulty of the measurement of such a thin stacked DEA arises from the friction and local deformation of the surface between the DEA and a contact, as shown in this paper. In the proposed method, a DEA is vertically suspended and a weight is attached to it. The proposed method requires no contact with the surface of a DEA and uses only a weighting mass. Experimental results demonstrated the proposed method can estimate almost essential constants, such as the dynamic elastic modulus (Young’s modulus and damping time constant), the electrical constants (permittivity and resistivity), and the coefficient of electromechanical coupling, through the forced vibration induced by voltage actuation.

Investigation on the dynamic performance of viscoelastic dielectric elastomer oscillators considering nonlinear material viscosity

2019 ◽  
Vol 30 (20) ◽  
pp. 3190-3199 ◽  
Author(s):  
Yuanping Li ◽  
Jianyou Zhou ◽  
Liying Jiang
Keyword(s):  
Electromechanical Coupling ◽  
Frequency Tuning ◽  
Dynamic Performance ◽  
Transient State ◽  
Dielectric Elastomer ◽  
Nonlinear Material ◽  
Dielectric Elastomers ◽  
Modeling Framework ◽  
Practical Applications ◽  
External Stimuli

As a typical kind of soft electroactive materials, dielectric elastomers are capable of producing large deformation under external stimuli, which makes them desirable materials for many practical applications in transduction technology, including tunable oscillators and resonators. The dynamic performance of such dielectric elastomer–based vibrational devices is strongly affected by material viscosity as well as electromechanical coupling. Moreover, as suggested by experiments and theoretical studies, dielectric elastomers exhibit deformation-dependent relaxation process, which makes the modeling of the dynamic performance of dielectric elastomer–based devices more challenging. In this work, by adopting the state-of-art modeling framework of finite-deformation viscoelasticity, the effect of the nonlinear material viscosity on the in-plane oscillation and the frequency tuning of dielectric elastomer membrane oscillators is investigated. From the simulation results, it is found that the nonlinear viscosity only affects the transient state of the frequency tuning process. The modeling framework developed in this work is expected to provide useful guidelines for predicting the dynamic performance of dielectric elastomer–based vibrational devices as well as their optimal design.

scholarly journals Soft, tough, and fast polyacrylate dielectric elastomer for non-magnetic motor

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Li-Juan Yin ◽  
Yu Zhao ◽  
Jing Zhu ◽  
Minhao Yang ◽  
Huichan Zhao ◽  
...  
Keyword(s):  
High Performance ◽  
Crosslinking Agent ◽  
High Energy ◽  
Dielectric Elastomer ◽  
High Energy Density ◽  
Dielectric Elastomers ◽  
Dielectric Elastomer Actuators ◽  
Response Bandwidth ◽  
Electrically Actuated ◽  
Soft Actuators

AbstractDielectric elastomer actuators (DEAs) with large electrically-actuated strain can build light-weight and flexible non-magnetic motors. However, dielectric elastomers commonly used in the field of soft actuation suffer from high stiffness, low strength, and high driving field, severely limiting the DEA’s actuating performance. Here we design a new polyacrylate dielectric elastomer with optimized crosslinking network by rationally employing the difunctional macromolecular crosslinking agent. The proposed elastomer simultaneously possesses desirable modulus (~0.073 MPa), high toughness (elongation ~2400%), low mechanical loss (tan δm = 0.21@1 Hz, 20 °C), and satisfactory dielectric properties ($${\varepsilon }_{{{{{{\rm{r}}}}}}}$$ ε r  = 5.75, tan δe = 0.0019 @1 kHz), and accordingly, large actuation strain (118% @ 70 MV m−1), high energy density (0.24 MJ m−3 @ 70 MV m−1), and rapid response (bandwidth above 100 Hz). Compared with VHBTM 4910, the non-magnetic motor made of our elastomer presents 15 times higher rotation speed. These findings offer a strategy to fabricate high-performance dielectric elastomers for soft actuators.

Dynamic instability of dielectric elastomer actuators subjected to unequal biaxial prestress

2017 ◽  
Vol 26 (11) ◽  
pp. 115019 ◽  
Author(s):  
Atul Kumar Sharma ◽  
S Bajpayee ◽  
D M Joglekar ◽  
M M Joglekar
Keyword(s):  
Dynamic Instability ◽  
Dielectric Elastomer ◽  
Dielectric Elastomer Actuators
Sign in / Sign up

Export Citation Format

Share Document