Styrenic-Rubber Dielectric Elastomer Actuator with Inherent Stiffness Compensation

• Main Authors: Giacomo Moretti, Luca Sarina, Lorenzo Agostini, Rocco Vertechy, Giovanni Berselli, Marco Fontana
• Format: Article
• Language: English
• Published: MDPI AG 2020-06-01
• Series: Actuators
• Subjects: dielectric elastomer; actuator; stiffness compensation; negative spring design
• Online Access: https://www.mdpi.com/2076-0825/9/2/44

Up to date, Dielectric Elastomer Actuators (DEA) have been mostly based on either silicone or acrylic elastomers, whereas the potential of DEAs based on inexpensive, wide-spread natural and synthetic rubbers has been scarcely investigated. In this paper, a DEA based on a styrene-based rubber is demonstrated for the first time. Using a Lozenge-Shaped DEA (LS-DEA) layout and following a design procedure previously proposed by the authors, we develop prototypes featuring nearly-zero mechanical stiffness, in spite of the large elastic modulus of styrenic rubber. Stiffness compensation is achieved by simply taking advantage of a biaxial pre-stretching of the rubber DE membrane, with no need for additional stiffness cancellation mechanical elements. In the paper, we present a characterization of the styrene rubber-based LS-DEA in different loading conditions (namely, isopotential, isometric, and isotonic), and we prove that actuation strokes of at least 18% the actuator side length can be achieved, thanks to the proposed stiffness-compensated design.