Large Electrostatic Deformation of a Dielectric Elastomer Annulus

A large quasi-static deformation analysis of a thin annulus made of dielectric elastomer is presented in this paper. The material is assumed to be perfectly elastic, isotropic, and incompressible. An electric field is applied through the thickness of the annulus. The outer periphery of the annulus is held fixed, while the inner periphery is free to move. The radial stress and strain distributions are determined using two nonlinear differential equations obtained from equilibrium, stress-strain and geometric relations. Mooney’s (1940) from of the strain energy function is used for the analysis. The non-linear differential equations are solved for the principal extension ratios, λ1 and λ2 , using Matlab’s two-point boundary value function BCP4C. The radial and circumferential stresses are calculated using the derived solutions. The resluts of the mathematical model showed that for increasing effective (squeeze) pressure, the readial and circumferential stress transitions from tensile to compressive states at a “critical” effective (squeeze) pressure. Also, for the annulus with non-zero hole pressure, there exists an operating range for both the hole pressure and effective (squeeze) pressure of which the model is mathematically as well as physically viable.Copyright © 2003 by ASME