Dynamic instability of dielectric elastomer actuators subjected to unequal biaxial prestress

Sharma, Atul Kumar; Bajpayee, S; Joglekar, Dhanashri M.; Joglekar, M. M.

doi:10.1088/1361-665x/aa8923

Cited by 45 publications

(14 citation statements)

References 53 publications

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“…Moreover, the constitutive relations of DEs are nonlinear, such that their instantaneous moduli vary as functions of the electromechanical loads. These features have led to the design of various applications, such as haptic devices (Kim et al, 2016), soft robots (Gu et al, 2018), actuators (Hajiesmaili & Clarke, 2021;Sharma et al, 2018Sharma et al, , 2019Su et al, 2018Su et al, , 2019Kashyap et al, 2020;Sharma et al, 2017;Khurana et al, 2021) and artificial muscles (Lu et al, 2016), that are based on DEs.…”

Section: Introductionmentioning

confidence: 99%

Gradient-based topology optimization of soft dielectrics as tunable phononic crystals

Sharma

Kosta

Gal

et al. 2022

Composite Structures

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Dielectric elastomers are active materials that undergo large deformations and change their instantaneous moduli when they are actuated by electric fields. By virtue of these features, composites made of soft dielectrics can filter waves across frequency bands that are electrostatically tunable.To date, to improve the performance of these adaptive phononic crystals, such as the width of these bands at the actuated state, metaheuristics-based topology optimization was used. However, the design freedom offered by this approach is limited because the number of function evaluations increases exponentially with the number of design variables. Here, we go beyond the limitations of this approach, by developing an efficient gradient-based topology optimization method for maximizing the width of the band gaps in an exemplary case study. We employ a finite element formulation of the governing equations, and use the properties of each element as the design variables. In order to iteratively update the design variables, we employ gradient-based optimization, namely the Method of Moving Asymptotes. We carry out and implement fully analytical sensitivity analysis for computing the gradient of the objective function with respect to each one of the design variables. The numerical results of the method developed here demonstrate prohibited frequency bands that are indeed wider that those that were generated using metaheuristics-based topology optimization, while the computational cost to identify them is reduced by orders of magnitude.

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Section: Introductionmentioning

confidence: 99%

Gradient-based topology optimization of soft dielectrics as tunable phononic crystals

Sharma

Kosta

Gal

et al. 2022

Composite Structures

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“…Hence, modeling the nonlinear dynamic responses of the DEMES actuator is an important task for the effective design of such devices. Specifically, for the dynamic behavior of the planar DEAs, several investigations considering the effect of prestressing or pre-stretch Dai and Wang (2015); Joglekar (2014); Sharma et al (2017), viscoelasticity Kollosche et al (2015); ; Zhao et al (2020), humidityZhang et al (2021, the initial stretch ratio Dai et al (2016), combined DC and AC voltage Khurana et al (2021a); Sasikala et al (2017); Sheng et al (2014) on the electromechanical behavior of the DEAs are available. Realistically, the inherent material nonlinearity of the DE membrane is scrutinized in all the above-stated work of DEAs.…”

Section: Introductionmentioning

confidence: 99%

An Energy-Based Nonlinear Dynamic Model of Dielectric Elastomer Minimum Energy Structures with Stiffeners: Equilibrium Configuration and the Electromechanical Response

Khurana

Patra

Joglekar

2021

Preprint

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The Dielectric Elastomer-based Minimum Energy Structures (DEMES) pertain to an equilibrium configuration attained by the assembly of a pre-stretched electroactive polymer film and a compliant boundary frame. Because of their unique characteristics, such as fast response and a large reversible stroke; DEMES have been used widely in the development of soft robotic transducers. However, their utility is typically restricted because of the warping resulting from anticlastic curvature. The present investigation examines the effectiveness of stiffeners in controlling this warping, as well as their effect on the resulting electromechanical response when the DEMES is driven electrically. To this end, we devise an energy-based analytical model that predicts the initial equilibrium configuration of an elementary rectangular DEMES with a finite number of stiffeners adhered to the boundary frame. The proposed framework uses the neo-Hookean hyperelasticity model for the polymer film and the linear elastic constitutive model for both the frame and the stiffeners. Predictive capability of the proposed analytical model is established through comparisons with 3D finite element simulations and experimental observations. The analytical model is then extended in the setting of the least-action principle to investigate the complex nonlinear dynamic behavior of the DEMES emanating from the interplay between material and geometric nonlinearities. The proposed dynamic model provides crucial insights into the role of varying levels of geometric and material parameters on the attainment of the initial equilibrium configuration of DEMES and its DC dynamic response when driven by a Heaviside electric load. In particular, we highlight the favorable impact of adding stiffeners in enhancing the stroke of the DEMES and an amplification in the attained equilibrium angle with an increasing spacing between the stiffeners. The analytical model and the results reported in this investigation can be of potential use in pre-designing the geometrical and material properties of DEMES for enhancing its electromechanical performance.

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“…The pullin instability parameters, i.e. electric field and corresponding actuation stretch strongly depend on the material model and on the other several factors, such as temperature, material permittivity and prestress [13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

“…The nonlinear oscillation of a thin circular DE membrane when subjected to combined mechanical and electrical loading was investigated by Zhu et al [32] who inferred that variation in the prestretch, pressure and voltage may be used for tuning the natural frequency of the membrane. The effects of several factors such as prestress [16], initial stretch ratio [33], viscoelasticity [34,35] and a combined DC and AC voltage [36] on the electromechanical performance of the DE transducers have been reported in the literature in the recent past. Liu et al [37] investigated the effect of viscoelasticity on the nonlinear dynamics of a DE balloon using the shooting and arc-length continuation method.…”

Section: Introductionmentioning

confidence: 99%

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DC dynamic pull-in instability of a dielectric elastomer balloon: an energy-based approach

Sharma¹,

Arora²,

Joglekar³

2018

Proc. R. Soc. A.

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This paper reports an energy-based method for the dynamic pull-in instability analysis of a spherical dielectric elastomer (DE) balloon subjected to a quasi-statically applied inflation pressure and a Heaviside step voltage across the balloon wall. The proposed technique relies on establishing the energy balance at the point of maximum stretch in an oscillation cycle, followed by the imposition of an instability condition for extracting the threshold parameters. The material models of the Ogden family are employed for describing the hyperelasticity of the balloon. The accuracy of the critical dynamic pull-in parameters is established by examining the saddle-node bifurcation in the transient response of the balloon obtained by integrating numerically the equation of motion, derived using the Euler-Lagrange equation. The parametric study brings out the effect of inflation pressure on the onset of the pull-in instability in the DE balloon. A quantitative comparison between the static and dynamic pull-in parameters at four different levels of the inflation pressure is presented. The results indicate that the dynamic pull-in instability gets triggered at electric fields that are lower than those corresponding to the static instability. The results of the present investigation can find potential use in the design and development of the balloon actuators subjected to transient loading. The method developed is versatile and can be used in the dynamic instability analysis of other conservative systems of interest.

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Dynamic instability of dielectric elastomer actuators subjected to unequal biaxial prestress

Cited by 45 publications

References 53 publications

Gradient-based topology optimization of soft dielectrics as tunable phononic crystals

Gradient-based topology optimization of soft dielectrics as tunable phononic crystals

An Energy-Based Nonlinear Dynamic Model of Dielectric Elastomer Minimum Energy Structures with Stiffeners: Equilibrium Configuration and the Electromechanical Response

DC dynamic pull-in instability of a dielectric elastomer balloon: an energy-based approach

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