Dielectric elastomer composites

Tian, Li; Tevet-Deree, L.; deBotton, Gal; Bhattacharya, Kaushik

doi:10.1016/j.jmps.2011.08.005

Cited by 97 publications

(121 citation statements)

References 13 publications

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“…Different from the traditional DEs, the effective electromechanical coupling in these particle/matrix composites becomes highly nonlinear, making it a challenging task to properly model such materials from theoretical point of view (Li B. et al, 2013). Some analytical efforts have been devoted to this problem, but most of them were limited to small strains (Tian et al, 2012). Although numerous DE structures and devices have been successfully modeled and analyzed, DE actuators with self-healing capability , increasing sophistication in stacking or even hierarchical configurations (Haus et al, 2013) require more theoretical effort to address the underlying challenges that impede the practical application of these smart materials in artificial muscles.…”

Section: Concluding Remarks and Outlookmentioning

confidence: 99%

Mechanics of dielectric elastomers: materials, structures, and devices

Qian

2016

JZUS-A

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Dielectric elastomers (DEs) respond to applied electric voltage with a surprisingly large deformation, showing a promising capability to generate actuation in mimicking natural muscles. A theoretical foundation of the mechanics of DEs is of crucial importance in designing DE-based structures and devices. In this review, we survey some recent theoretical and numerical efforts in exploring several aspects of electroactive materials, with emphases on the governing equations of electromechanical coupling, constitutive laws, viscoelastic behaviors, electromechanical instability as well as actuation applications. An overview of analytical models is provided based on the representative approach of non-equilibrium thermodynamics, with computational analyses being required in more generalized situations such as irregular shape, complex configuration, and time-dependent deformation. Theoretical efforts have been devoted to enhancing the working limits of DE actuators by avoiding electromechanical instability as well as electric breakdown, and pre-strains are shown to effectively avoid the two failure modes. These studies lay a solid foundation to facilitate the use of DE materials, structures, and devices in a wide range of applications such as biomedical devices, adaptive systems, robotics, energy harvesting, etc.

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Section: Concluding Remarks and Outlookmentioning

confidence: 99%

Mechanics of dielectric elastomers: materials, structures, and devices

Qian

2016

JZUS-A

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“…This is because at intermediate angles the layers can rotate to avoid instability. We recall that layer rotation is also a mechanism for large actuation [20,21]. This region of stability closes at sufficiently high electric fields.…”

Section: Introductionmentioning

confidence: 80%

“…This approach has been shown to be promising in experiments [8,18]. Moreover, theoretical estimations [19][20][21] show that the experimental results are only a beginning, and proper optimization of the microstructure can lead to orders of magnitude improvement in electromechanical coupling.…”

Section: Introductionmentioning

confidence: 99%

“…The second point of departure from previous work is that we formulate the equations for anisotropic media. This is important as the effective microstructures resulting in large coupling [20,21] the electric field and mechanical loading are applied at an arbitrary angle to the layers. Again, this is motivated by considerations of enhanced actuation [20,21].…”

Section: Introductionmentioning

confidence: 99%

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Multiscale instabilities in soft heterogeneous dielectric elastomers

2014

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The development of instabilities in soft heterogeneous dielectric elastomers is investigated. Motivated by experiments and possible applications, we use in our analysis the physically relevant referential electric field instead of electric displacement. In terms of this variable, a closed form solution is derived for the class of layered neo-Hookean dielectrics. A criterion for the onset of electromechanical multiscale instabilities for the layered composites with anisotropic phases is formulated. A general condition for the onset of the macroscopic instability in soft multiphase dielectrics is introduced. In the example of the layered dielectrics, the essential influence of the microstructure on the onset of instabilities is revealed. We found that: (i) macroscopic instabilities dominate at moderate volume fractions of the stiffer phase, (ii) interface instabilities appear at small volume fractions of the stiffer phase and (iii) instabilities of a finite scale, comparable to the microstructure size, occur at large volume fractions of the stiffer phase. The latest new type of instabilities does not appear in the purely mechanical case and dominates in the region of large volume fractions of the stiff phase.

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“…As noted above, we will work with a charge density field ρ and assume that the coarse-graining is also valid for point charges by replacing ρ with appropriate Dirac masses. Our starting point is to write ρ following the ideas of 2-scale methods [All92,TTDDB12]. I.e., we consider the setting where the charge density varies over 2 different lengthscales.…”

Section: Coarse-graining the Electrostatic Field Energymentioning

confidence: 99%

Atomistic-to-continuum multiscale modeling with long-range electrostatic interactions in ionic solids

Marshall

Dayal

2014

Journal of the Mechanics and Physics of Solids

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We present a multiscale atomistic-to-continuum method for ionic crystals with defects. Defects often play a central role in ionic and electronic solids, not only to limit reliability, but more importantly to enable the functionalities that make these materials of critical importance. Examples include solid electrolytes that conduct current through the motion of charged point defects, and complex oxide ferroelectrics that display multifunctionality through the motion of domain wall defects. Therefore, it is important to understand the structure of defects and their response to electrical and mechanical fields. A central hurdle, however, is that interactions in ionic solids include both short-range atomic interactions as well as long-range electrostatic interactions. Existing atomistic-to-continuum multiscale methods, such as the Quasicontinuum method, are applicable only when the atomic interactions are short-range. In addition, empirical reductions of quantum mechanics to density functional models are unable to capture key phenomena of interest in these materials.To address this open problem, we develop a multiscale atomistic method to coarse-grain the longrange electrical interactions in ionic crystals with defects. In these settings, the charge density is rapidly varying, but in an almost-periodic manner. The key idea is to use the polarization density field as a multiscale mediator that enables efficient coarse-graining by exploiting the almost-periodic nature of the variation. In regions far from the defect, where the crystal is close-to-perfect, the polarization field serves as a proxy that enables us to avoid accounting for the details of the charge variation. We combine this approach for long-range electrostatics with the standard Quasicontinuum method for short-range interactions to achieve an efficient multiscale atomistic-to-continuum method. As a side note, we examine an important issue that is critical to our method: namely, the dependence of the computed polarization field on the choice of unit cell. Potentially, this is fatal to our coarse-graining scheme; however, we show that consistently accounting for boundary charges leaves the continuum electrostatic fields invariant to choice of unit cell.

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Dielectric elastomer composites

Cited by 97 publications

References 13 publications

Mechanics of dielectric elastomers: materials, structures, and devices

Mechanics of dielectric elastomers: materials, structures, and devices

Multiscale instabilities in soft heterogeneous dielectric elastomers

Atomistic-to-continuum multiscale modeling with long-range electrostatic interactions in ionic solids

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