Electro-viscoelastic performance of a tubular dielectric elastomer actuator

To reveal the electro-viscoelastic performance of a tubular dielectric elastomer actuator, a dissipative model for the actuator is formulated by adopting the nonlinear theory of viscoelastic dielectrics. The actuator is made by rolling a layer of dielectric elastomer membrane into a tube, which is then fixed tightly with two rigid disks at top and bottom edges respectively. Once actuated by internal pressure and voltage, the tube inflates and deforms into an out-of plane shape, undergoing large deformation. To depict the deformation, the non-equilibrium thermodynamics is employed to derive the state equations and the governing equations, and to characterize the dissipative process, a rheological spring-dashpot model is applied to obtaining the kinetic equations. Numerical simulation is conducted by a joint use of the shooting method and the improved Euler method, and the variations of the considered variables and the profiles of the deformed tube are obtained and demonstrated graphically. The effects of the internal pressure, the voltage as well as the aspect ratio of the tube on the performance of the actuator are considered. The results show that for small pressure or small voltage, the actuator can eventually evolve into a stable state, while for large pressure or large voltage, the actuator can’t reach a stable state due to the occurrence of purely mechanical instability or electromechanical instability. As for the aspect ratio, it significantly influences the performance of the actuator. It is hoped that the approach may provide a better understanding of the electro-viscoelastic performance of such actuators and some guidelines in designing such actuators.