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Description
Dielectric Elastomers have the potential of exhibiting large strains when the material is in the presence of an electric field. The dielectric in this case is a soft acrylic (VHB 4910) film that is sandwiched between two compliant electrodes that are subjected to a high voltage potential. When high voltage is applied, attracting charges lead to a contractive force known as electrostatic pressure. The electrostatic pressure deforms the elastomer membrane and the contraction occurs in the thickness (z plane) direction, which leads to actuation and expansion of the film. The pressure in the z direction is usually governed by electrostatic pressure from Pelrine, $\rho=\epsilon_0\epsilon_rE^2$. In the Pelrine model the relative permittivity is held constant when calculating for pressure. Recent research has found that relative permittivity in this case is not at all constant. New literature has shown that permittivity decreases as stretch rates increase. From a microscopic level, polarization within the DEA determines the material's permittivity, which makes it deformation dependent. This work looks to investigate, theoretically and experimentally, a polarization dependent electrostatic pressure model. Using the Tettex 2822 measuring system we can back-solve for the permittivity of the DEA as a function of stretch. This data was collected and used to find a best fit curve to determine various permittivity ranges of the DEA from its relax state to its max deformation.
