Effects of Dielectric Film Viscoelasticity on Dynamic Behavior of Dielectric Elastomer Minimum Energy Structure

In this paper nonlinear dynamic behavior of bending actuators of dielectric elastomer or Dielectric Elastomer Minimum Energy Structure (DEMES) is studied and the effects of viscoelasticity of dielectric film on system response are investigated. Considering hyper-elasticity and viscoelasticity of dielectric film, the equation of motion of the actuator is extracted using Euler-Lagrange method. The natural frequency of small amplitude oscillations around the equilibrium state is calculated by linearizing the original nonlinear equation and the effects of dielectric film pre-stretch and excitation amplitude on natural frequency is investigated. The numerical simulation of the nonlinear equation of motion for periodic excitation shows that the system possesses harmonic resonances as well as sub-harmonic and super-harmonic resonances. By increasing the damping ratio of the dielectric film, resonance frequency increases for all harmonics and their excitation amplitude decreases. The analytical results show that excitation amplitude of harmonic resonance in chaotic behavior changes to a quasi-alternate and then an alternative behavior by increasing damping ratio.