Control instability and enhance performance of a dielectric elastomer balloon with a passive layer

Dielectric elastomer (DE) balloons, which are widely used as sensors, actuators, and generators, can show large deformations under the influence of internal pressure and electric voltage. In these nonlinear systems, there exists electromechanical instability (EMI), which when combined with material failures, can hinder the generation of large voltage-induced deformations. Moreover, it is important to guarantee electrical safety by providing insulation for the DE balloon. In this paper, we introduce an external passive layer for the DE balloon, considering both protection and performance enhancement. We demonstrate that the EMI can be suppressed or eliminated, and that large voltage-induced deformations can be achieved with the passive layer. Specifically, the coupling model for the DE balloon and the passive layer is derived. With this model, we study the effect of the thickness and shear modulus of the passive layer on the instability and electromechanical performance. Furthermore, we identify five types of failure modes and obtain their dependence on the thickness and shear modulus. The transition between two failure modes and the transition from small to large voltage-induced deformations within one failure mode can be realized by varying the parameter of the passive layer. This research thus provides insights for the design of dielectric elastomer actuators, where both safety and performance are important.