Small-Strain Modeling of Helical Dielectric Elastomer Actuators

The helical configuration represents one of the few currently available to implement contractile Dielectric Elastomer (DE) actuators. While experimental investigations have previously been reported, no model is currently available to assist design. This paper describes a simple analytical electromechanical model of helical DE actuators, applicable for relatively small strains (<10%), consistently with the following assumptions: the effective electrostatic pressure exerted by the compliant electrodes was considered to be constant during actuation; the elastomer was assumed to behave like a linearly elastic body. According to these assumptions, the electromechanical model was derived by means of independent electrical and mechanical analyses, the latter being based on linear elasticity. To validate the model, theoretical predictions were compared with experimental data measured from a silicone-made prototype actuator. Pros and cons of the modeling approach in the small-strain range are discussed.