Modelling of dielectric elastomer loudspeakers including dissipative effects

Abstract

This contribution presents a theoretically investigation of dielectric elastomer loudspeakers similar in design to the loudspeakers studied at SRI International more than 10 years ago. The main emphasis of the contribution is on the effect of dissipative effects, specifically radiative losses (acoustic losses). The starting point of the theoretical model is a free-energy description and include hyper-elastic contributions. In the designs considered in this work the dielectric elastomer material is subject to a pre-strain which has been applied either by subjecting the membrane to an applied back pressure, or simply applying a biaxial mechanical pre-strain. The membrane is then actuated relative to this pre-strain by the application of an applied ac voltage. The nonlinear equations are linearized around the given pre-strain in order to perform relatively fast calculations of the mechanical frequency response of the structure.