Development of Devices Based on Electrically Actuated Soft Elastomers

Calabrese, Luigi (2019) Development of Devices Based on Electrically Actuated Soft Elastomers. PhD thesis, University of Trento.

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Dielectric elastomer (DE) actuators are electromechanical transducers that essentially consist of one layer of an insulating soft elastomer coated on both sides with com- pliant electrodes. When a voltage is applied between the electrodes, an electrostatic pressure deforms the elastomer triggering the motion of the actuator. In this the- sis, this principle is exploited for the development of three different actuators: an electroactive compression bandage, a hydrostatically coupled actuator for use in the field of soft manipulators and a dielectric elastomer based inchworm-like robot able to perform locomotion. By doing so, several challenges related to the design, to the modeling and to the manufacturing of this kind of devices are raised and tackled. During the development of the electroactive compression bandage, the issue of electrical insulation and prevention of electrical discharge in wearable devices was addressed by using coating layers as an interface between the DE actuator and the human body. Both experimental investigations and a finite electro-elasticity analyti- cal model showed that the passive layers play a key role for an effective transmission of the actuation from the active layers to the load. Indeed, the model showed that by increasing the number of electroactive layers, the pressure variation can be increased, although with a saturation trend, providing a useful indication for future designs of such bandages. The second piece of work here reported consists in a design upgrade of the Hy- drostatically Coupled Dielectric Elastomer Actuator (HC-DEA), already known in the literature, that enable its use in the field of soft manipulators. The new design fea- tures segmented electrodes, which stand as four independent elements on the active membrane of the actuator, enabling it for generating both out of plane and in plane motions. This novel design makes the actuator suitable for delicate transportation of a flat object. This capability was proven via an experimental investigation in which a flat Petri dish was roto-translated on a platform composed of two actuators. The electromechanical transduction performance of the actuator was characterized and its contact mechanics was modeled. Finally, a smart robot structure that exploits anisotropic friction to achieve stick- slip locomotion is presented. The robot, which is made out just of a plastic beam, a planar dielectric elastomer actuator and four bristle pads with asymmetric rigid metallic bristles, exploits the resonance condition to reach the maximum locomotion speed. The fundamental frequency of the structure, which was estimated both ana- lytically and numerically, was identified within the range of frequencies in which the top locomotion speed was observed during the experiments to be identified.

Item Type:Doctoral Thesis (PhD)
Doctoral School:Civil, Environmental and Mechanical Engineering
PhD Cycle:31
Subjects:Area 08 - Ingegneria civile e Architettura > ICAR/08 SCIENZA DELLE COSTRUZIONI
Repository Staff approval on:05 Aug 2019 08:44

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