A dielectric elastomer membrane integrated with protective passive layers under explicit and implicit prestretch

Dielectric elastomers (DEs) are a category of soft electro-active materials that can be used as sensors, actuators and generators. In order to provide protection, insulation layers are essential and thicker layers can lead to stronger protecion. However, the presence of the additional layers can certainly constrain the deformation of DEs. Thus a balance between protection and performance is needed.Prestretch is widely used for the enhancement of actuation performance. Thus the DE membrane integrated with protective passive layers is studied here, focusing on the effect of the coexistence of the prestretch and passive layers. We identify two approaches of prestretches, where the DE membrane and protective passive layers can be explicitly prestretched by external loads, or the DE membrane can be implicitly prestretched by solely protective passive layers. For the latter approach, it does not require additional components such as rigid clamps or dead weights. We then establish a coupled model for the DE membrane and passive layers. The effects of the prestretches and passive layers on the electromechanical behavior and voltage-induced deformation of the DE membrane are then revealed numerically. Furthermore, we theoretically study the detailed effects of specific mechanical properties of passive layers such as the thickness and shear modulus, which are useful for the design of the system. This theoretical research thus sheds insights for the design of dielectric elastomer applications where both safety and performance are required.