Geometric optimization of dielectric elastomer electrodes for dynamic applications

Dielectric elastomers are soft actuators, made of an elastomer membrane sandwiched by compliant electrodes. Because of their high energy density and quick response, they are well suited for dynamic applications such as loudspeakers. Thanks to progress in the manufacturing process of dielectric elastomer actuators, the electrode shape can be patterned to very diverse shapes. In this study, we focus on the relation between the electrode shape and the dynamical and acoustical behavior of a dielectric elastomer loudspeaker. By using a finite element model of the loudspeaker, an optimization algorithm is set up to compute optimal electrode shapes according to chosen objectives, such as maximizing or minimizing the contribution of an eigenmode to the radiated sound. The optimal designs are then tested experimentally, and the efficiency of the optimization procedure is assessed. It is shown that the frequency response of dielectric elastomer loudspeakers can be tuned by optimizing the shape of the electrodes, and simulations suggest that the directivity can also be controlled. Finally, perspectives of the proposed optimization method are briefly discussed. (C) 2021 Elsevier Ltd. All rights reserved.