Wave Propagation in Viscoelastic Dielectric Elastomer Media
Abstract
Dielectric elastomers (DEs) are capable of producing large deformation under electric stimuli, which makes them desirable materials for a variety of applications including biomimetics, dynamics, robotics, energy harvesting, and waveguide devices. In general, DEs possess intrinsic hyperelasticity and viscosity. Such material properties may significantly affect the dynamic performance of DE-based devices. The delicate interplay among electromechanical coupling, large deformation, material viscosity and dynamics makes modeling of the performance of DE-based devices more challenging. Therefore, in order to provide guidelines for the optimal design of DE waveguide devices, it is essential to develop appropriate and reliable models, and efficient numerical methods to examine their performance first.
In this thesis, by integrating the state-of-art finite-deformation viscoelasticity theory into the framework of small-amplitude wave propagation superposed on a finitely deformed medium, the Rayleigh-Lamb wave propagation in a viscoelastic DE medium is investigated. Simulation results have demonstrated the effects of material viscosity, status of relaxation, external electric load, and mechanical pre-stretch on the dispersion behavior of the wave. For both pure elastic and viscoelastic DE media, waves with certain frequencies could be filtered by actively tuning electric loads. Moreover, some interesting findings conclude that the material viscoelasticity may cause some significant changes in the wave dispersion behavior. Therefore, incorporating the material viscosity in modeling DE waveguide is expected to provide more accurate prediction on their performance. This thesis will help to better understand the fundamentals of wave propagation in DE media and trigger more innovative and optimal design for DE waveguide applications.