A numerical study on electrostrictive visco-hyperelastic actuators and generators

In this research, we develop a numerical framework capable of evaluating the electrostriction effect on the electrostatic, finite deformation and viscoelastic response of dielectric elastomers. The principle of virtual work is employed to derive the governing equations and their weak form. The Zener rheological model is adopted for viscoelastic modeling. The constitutive equations incorporate the electrostriction effect into viscoelastic dielectric elastomers. The applications of this paper include a 3D torsional actuator and a circular diaphragm generator. The inhomogeneous displacement fields and complex geometry of these applications necessitate the use of the finite element method. Based on the applications, two types of elements are designed and verified: a 3D element and an axisymmetric element. The effects of two decisive factors in viscoelasticity, i.e., the viscosity parameter and the loading rate, are studied on the response of the actuator in the presence of electrostriction. The results demonstrate significant improvements by accounting for electrostriction in both actuator performance and operating voltage. Investigating the effect of electrostriction on the energy harvesting cycle of the generator with various viscosity parameters reveals that a more negative (positive) electrostrictive coefficient results in greater (smaller) mechanical and electrical work and lower (higher) cycle efficiency.