Papers by Author: Guggi Kofod

Abstract: The cuboid actuator is presented as a simple system for evaluation of the properties of dielectric elastomer actuators. The Ogden model as a component of this theory is evaluated and parameters for VHB 4910 found in literature are compared. The model is presented and evaluated with both intensive and extensive variables. For the first time direct effects of the width prestretch on electromechanical coupling are clearly presented. Also, the importance of choosing proper parameters for the hyper-elastic model is made clear via example.

Abstract: Dielectric elastomer actuators based on Maxwell-stress induced deformation, are considered for many potential applications where high actuation strain and high energy density are required. They usually rely on a planar actuator configuration, however, a string-like actuator would be less bulky, and more versatile for several applications. In this paper, a co-axial dielectric elastomer actuator that produces relatively high actuation strain is presented. The actuator is manufactured through alternating dip-coating steps with insulating and conductive thin layers. A soluble thermoplastic block-copolymer, SEBS(poly-(styrene-ethylene-butylene-styrene), is used for the dielectric layers as well as for the host material of the compliant electrodes. Electrical conductivity of the electrodes is achieved by incorporation of conductive carbon-black particles in the elastomer matrix. Actuators with a single and with multiple active layers (up to three) have been successfully demonstrated. This geometry is advantageous in that it is compact and can be bundled easily, and should therefore be practical in applications such as “artificial muscles”.