Method to analyze electromechanical stability of dielectric elastomers

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Wiki entry by : Dongwoo Lee, AP225 Fall 2010.

Paper in this Wiki : Xuanhe Zhao, Z. Suo, Method to analyze electromechanical stability of dielectric elastomers, Applied Physics Letters 91, 061921 (2007).


The authors talk about the analysis of electromechanical stability of dielectric elastomers. When the thickness of a layer of a dielectric elastomer reduces because of an electric voltage input, the elastomer experiences drastic shrinking, resulting in an electrical breakdown. It is possible to analysis this phenomenon with Hessian of the free-energy function. Fig. 1 shows the schematic diagram of the system that is considered in this paper, and Fig. 2 contains the derived equation for the system; Hessian. The authors show that the electromechanical instability occurs when the Hessian of the free-energy function ceases to be positive definite. In the figure 3, the function <\math>E<\math> has a peak. the left-hand side of eash curve has a positive definite Hessian, the right side has a non-positive-definite Hessian, and the peak has det(H)=0.