This presentation describes the design, manufacturing and testing of an inflatable Dielectric Elastomer Generators (DEGs) with a stadium shape that is intended to be used as integrated prime-mover and power-take-off system of a submerged-membrane pressure-differential Ocean Wave Energy Converter (OWEC). Results highlight the good performances of the developed stadium-shape DEG and its potentialities within the considered OWEC.
Nowadays, several industrial manufacturing processes imply direct cooperation between human operators and robots. This increases production and quality while improving the working conditions. However, the possible presence of physical contact between humans and robots asks for the study and introduction of new technical solutions that aim at guaranteeing a safe Human-Robot Interaction (HRI). Specifically, in recent years, different sensing devices have been developed for collision avoidance monitoring in HRI applications. Generally, common solutions consist of distributed resistive or capacitive sensors networks connected to a central electronic reading board, resulting in a cumbersome layout covering the whole parts of the collaborative robots. In this context, this paper presents an innovative tactile and proximity sensing strategy based on a soft-sensor module that can be installed on the collaborative robot parts or surrounding workspace. The developed module consists of a capacitive sensor based on a silicone elastomer membrane with compliant electrodes attached to the surface, disposed homogeneously on a deformable hemisphere-shape made of silicone. Thanks to the geometrical layout, such a sensor allows multidirectional objects detection resulting in a promising non-invasive solution for collisions avoidance in HRI applications. This work reports the design, manufacturing, and preliminary experimental investigation of such a sensor module, evaluating the electrodes geometry and the most relevant features that optimize objects detection distance and directivity sensing performance.
Flexible thin-film Electro-Adhesive Devices (EADs) represent a promising technology with great potential for gripper applications. Generally, the gripping action of an EAD is due to the electrostatic force induced by an electric field produced by applying a voltage across a couple of electrodes that are embedded between dielectric substrates. This paper presents a novel manufacturing process and the experimental characterization of a multilayer electro-adhesive gripper. The proposed device employs highly elastic silicone (PDMS) thin-film as the grasping layer, i.e., the dielectric layer that comes in contact with the grasped object, a carbon-black mixture in a silicone compound for the electrodes, and a rigid polyimide thin-film as the backing layer, i.e., the dielectric layer on the backside of the EAD. A fabrication methodology is illustrated, which starts from a casting of thin conductive electrodes on a polyimide film, followed by a laser-cutting operation to shape the electrodes and a blade casting process to encapsulate the overall system in a PDMS compound. Different prototypes obtained through this manufacturing procedure have been experimentally evaluated through a testing campaign conducted on three groups of specimens, each composed of five identical samples, with a different electrode thickness per group. Samples are tested for electrostatic shear stress and electrical breakdown during the grasping of paper substrates, identifying the best performing EAD group.
Dielectric Elastomers (DEs) are deformable dielectrics that can be used as active materials in mechatronic transducers, such as actuators, sensors and generators. Focusing on actuation systems, several kinds of DE actuators have been proposed in the literature, being characterized by various shapes/sizes and disparate performances in terms of efficiency, force/power densities and reliability. In any case, up to date, these devices are mostly based on either silicone or acrylic elastomers. On the other hand, actuator prototypes, which exploit the electromechanical properties of styrenic rubber, have been scarcely considered. Therefore, in this paper, a styrene-based-rubber Lozenge-Shaped DE Actuator (LS-DEA) is proposed and its performance are empirically evaluated. In particular, after material characterization and on the basis of a design procedure previously proposed by the authors, it is practically shown how it is possible to optimize the LS-DEA elastic response in order to tailor the application requirements and also (if needed) to obtain a nearly-zero mechanical stiffness. Several experimental results are henceforth provided, as a basis to highlight advantages and disadvantages of styrenic rubber LS-DEA over similar acrylic or silicone-based devices
Dielectric Elastomer Transducers (DETs) are a promising technology for the development of actuators, generators and sensors with high performance and low cost. Practical application and economic viability of DETs is strongly affected by their reliability and lifetime, which depend on the maximum strain and electrical loads that are cyclically applied on such devices. To date, only limited information is available on the fatigue life performances of dielectric elastomer materials and of the transducers made thereof. This paper reports on a first lifetime constant electric-stress test campaign conducted on 38 free-expanding frame-stretched circular DET specimens, made of the silicone elastomer film Elastosil 2030 250/150 by Wacker with blade-casted carbon-black silicone-elastomer electrodes, that have been subjected to nearly square wave electric field signals with 1 Hz frequency, 50% duty cycle and with amplitudes ranging from 65 MV/m to 80 MV/m.
Dielectric Elastomer Transducers (DETs) represent an emerging technology with great potential for mechatronic applications. DETs allow to convert electrical energy into mechanical energy and vice-versa, making it possible to design actuators, generators, and sensors. These devices show many advantages like high energy density, silent operations, and low cost, but their practical applicability is strongly affected by their reliability and lifetime, which depend on both environmental conditions and electro-mechanical loads. Theoretical and experimental studies have recently been initiated to investigate the lifetime ranges of such devices for different loading conditions (e.g., mechanical, electrical, electromechanical). At present, the lifetime characterization of DETs has been conducted by means of stochastic models only. In principle, a better understanding of electro-mechanical fatigue mechanism of DETs can be obtained through an appropriate analysis of their underlying physics. In this context, this paper presents a novel modeling approach for electro-mechanical damage evolution of DETs. In order to describe the phenomena involved in the damage process in physically consistent way, a free-energy framework is adopted. Starting from well-established electro-mechanical free-energy functions, additional variables which account for both mechanical and electrical fatigue mechanisms are introduced. Singular models for damage accumulation are developed and integrated within the free-energy conservation principle, in order to dynamically simulate the life status of the dielectric material when subjected to combined electric and mechanical loads. Finally, the kinetic law for damage evolution history due to combination of different failure modes are introduced, and used to assess DETs reliability based on experimental observations.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.