Model-based parameter analysis of dielectric elastomer loudspeakers

Abstract

Dielectric elastomers (DEs) are polymeric multifunctional materials that can be used to develop lightweight electrostatic actuators. Among other, DEs allow developing coilfree loudspeakers, in which the acoustic diaphragm and the actuator are embedded into a single DE membrane, whose deformations are driven by electrostatic stresses. In this paper, we present a simulation analysis of a DE loudspeaker with the aim of highlighting the effect of relevant design parameters (namely, the DE membrane thickness, diameter, and geometric aspect ratio) on the acoustic response. For the sake of illustration, we make reference to a simple loudspeaker layout, which does not require any mechanical or pneumatic biasing elements, and only consists in a DE membrane pre-loaded offplane. Based on a validated finite element multi-physics model of the system, we discuss how the system response (namely, eigenfrequencies and generated sound pressure level) varies with the design parameters. The presented results point out thresholds and trends that are relevant for the choice of DE loudspeakers' design parameters.