Abstract
Experimental observations clearly show that the performance of dielectric elastomeric-based devices can be considerably improved using composite materials. A critical issue in the development of composite dielectric materials toward applications is the prediction of their failure mechanisms due to the applied electromechanical loads. In this paper we investigate analytically the influence of electromechanical finite deformations on the stability of multilayered soft dielectrics under plane-strain conditions. Four different criteria are considered: (i) loss of positive definiteness of the tangent electroelastic constitutive operator, (ii) existence of diffuse modes of bifurcation ( microscopic modes), (iii) loss of strong ellipticity of the homogenized continuum (localized or macroscopic modes), and (iv) electric breakdown. While the formulation is developed for generic isotropic hyperelastic dielectrics, results are presented for the special class of ideal dielectrics incorporating a neo-Hookean elastic response. The effect of material properties and loading conditions is investigated, providing a detailed picture of the different possible failure modes.
Highlights
The application of a voltage through electrodes to soft dielectric elastomers deforms them substantially, giving us the opportunity to use this principle to design a new class of actuators
Soft composite dielectrics show great potential in the design of smart devices based on electrosensitive polymers, since their use allows the application of lower voltages as a result of the increased overall dielectric constant
A critical issue related to their development is the prediction of both global and local instabilities that may occur at the macro or at the micro-scale, respectively
Summary
The application of a voltage through electrodes to soft dielectric elastomers deforms them substantially, giving us the opportunity to use this principle to design a new class of actuators. A significant challenge in the development of devices based on dielectric elastomers is that they often require the application of extremely high voltages as a result of the material low dielectric constant. This represents a clear limitation in their development toward further applications, but both experimental (Zhang et al, 2002; Huang et al, 2004; Carpi et al, 2008b) and analytical (deBotton et al, 2007) investigations showed that composite materials can provide a solution to this critical issue. The results clearly show that depending on the heterogeneity contrast between the phases and on the loading conditions different failure modes may occur
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