Finite element simulation of plane strain dielectric elastomer membranes actuated by discretized electrodes

Abstract

Dielectric elastomers represent an attractive technology for smart actuator, sensor, and generator systems. In order to estimate how the performance of a membrane dielectric elastomer actuator (DEA) changes with the available design parameters (e.g., geometry, electrodes), numerous characterization experiments have to be performed. Alternatively, accurate simulations tools capable of predicting the system performance can be used to effectively optimize the design of DEA applications. In particular, Finite Element (FE) simulations allow to map global quantities as well as locally distributed quantities such as stress and strain fields as well as the electric field, and therefore appear as suitable for applications in which complex membrane geometries or electrode patterns are used. In this work, an FE model based on Comsol Multiphysics is introduced. This model is based on an electro-mechanically coupled formulation for large deformations, which also includes viscoelastic effects and electrodes geometry, while neglecting inertial effects. Due to the poor aspect ratio of membrane structures discretized with three-dimensional continuum elements, computation times appear as excessively large. To overcome this issue, the geometry is reduced to a two-dimensional structure. In order to simulate the local electric field distribution, both electrodes are discretized separately. For model identification and validation, specimens with and without imprinted electrodes are tested. Based on the developed model, the influence of the discretized electrodes is then examined, by varying electrode dimensions. Furthermore, fringe fields at the electrode edges are investigated in order to better understand local phenomena, e.g., the electrical breakdown mechanisms.