Stability analysis of dielectric elastomer using the elastic strain energy function with two material constants

Dielectric elastomers (DE) are the most promising electroactive polymer materials capable of being applied in smart actuators. When the DE film sandwiched between two compliant electrodes is applied high electric field, due to the electrostatic force between two electrodes, the film expands in-plane and contracts out-of-plane such that its thickness becomes thinner. The thinner thickness results in higher electric field which inversely squeezes the film again. This positive feedback induces a mode of instability, known as electromechanical instability or pull-in instability. When the electric field exceeds certain critical value, the DE film collapses. In this paper, the elastic strain energy function with two material constants is applied to analyze the stability of dielectric elastomers, which facilitates to understand fully Suo's nonlinear theory. The results verify again the truth of this theory and exploit larger application spectrum. The method is capable of analyzing the stability of different dielectric materials with different values of k and the result can be useful on design of the dielectric elastomer actuator.