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Title: Characterization of Mechanical and Electrical Properties of Dielectric Elastomer for Actuator Applications
Authors: Sahu, R. K.
Keywords: Mechanical Engineering
Issue Date: 2015
Publisher: IIT Patna
Abstract: Recently, a new class of elastomer capable of responding to external electrical field by displaying significant change in shape and size has emerged. These responsive elastomers which are also known as dielectric elastomers are becoming potential actuator materials in the ever growing field of mechatronics, robotics, bionics, etc. Designing of dielectric elastomer actuator, however, has been challenging due to nonlinear rate-dependent material responses to mechanical and electrical stimulations, multiple modes of failure, multiple parameters of design, and difficulties in measurement of the actuator performance characteristics. The effective application of dielectric elastomer for actuators requires good understanding of the rate-dependent mechanical and electrical properties. In addition, more theoretical attention is required to predict these highly nonlinear rate-dependent properties. Therefore, experimental analysis and modeling of the different mechanical and electrical properties are essential, and will facilitate optimum designing of products that incorporate elastomeric actuators. In this work, comprehensive mechanical and electrical characterizations of acrylic dielectric elastomer are performed for its actuator applications. Mechanical characterizations of the material are illustrated through various standard tests such as monotonic tensile tests, loading-unloading tests, cyclic loading-unloading tests, relaxation and creep tests. Attempts are made to develop modeling techniques such as visco-hyperelastic constitutive model and artificial neural network model which can describe the rate-dependent large deformation behaviors of the dielectric elastomer material. Stretch and frequency dependent dielectric properties like dielectric permittivity, dielectric strength and dissipation loss are investigated experimentally. The present work also describes the development of a novel pre-straining fixture for actuator fabrication. The effects of mechanical and dielectric properties on actuator performance are analyzed through several actuation tests in a circular planar actuator. Estimation of electromechanical coupling which is commonly described by Maxwell stress is considered as one of the key steps for design and optimization of dielectric elastomer (DE) actuator. More precise and accurate estimation of Maxwell stress is performed in this work by considering variation of dielectric constant with respect to frequency, pre-stretch and types of electrodes. Estimated Maxwell stress has been validated through mechanical compression test results.
Appears in Collections:02. ME

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