Modelling of spring roll actuators based on viscoelastic dielectric elastomers

In this article, the effect of viscoelastic deformation is analyzed theoretically to evaluate the performance of spring roll dielectric elastomer (DE) actuators. By patterning the electrodes on the rolls, respectively, two functions are studied: axial elongation and bending. The thermodynamic model of viscoelastic DE spring roll is established, and the governing equation is deduced by the free energy method. It is found that when the applied voltage is static and relatively small, both the axial elongated and bending deformed spring rolls can reach equilibrium after viscoelastic relaxation. The evolutions in different timescales and the final profile are presented. The dynamic response is studied as well, by applying a sinusoidal voltage. For the axial elongated spring roll, viscoelasticity can reduce amplitude and increase mean stretch of the actuator. For the bending deformed spring rolls, the results indicate that the spring stiffness has a more significant impact on dynamic performance compared to the effect of voltage.