Stroke Magnification in Dielectric Elastomer Actuators with Dynamic Excitation

Abstract:
Dielectric elastomer (DE) membrane actuators are known to provide high strokes compared to DE stack actuators. A graphical method can be used to design a membrane actuator system (combination of membrane DEA and biasing elements) for a specific application. This method considers the equilibrium of forces at steady-state, and thus completely neglects the dynamic behavior, such as inertial effects. Since the design is based on low frequencies, the resulting system designed is not expected to provide satisfactory performance in dynamic applications, as well. To overcome this issue, in this work we extend the quasi-static approach by including the effects of inertia force in a strip actuator system design. This allows to design a linear biasing spring in terms of spring rate and pre-compression, in order to tune the system resonance at a desired frequency. It is shown that this approach allows a stroke magnification in a range, which is typically only possible by means of complex non-linear biasing elements. Finally, the extended graphical model is used to predict the dynamic behavior of a DEA-spring-system.