Highly deformable actuators made of dielectric elastomers clamped by rigid rings

Abstract

In the nascent field of soft machines, soft materials are used to create devices that actuate robots, sense environment, monitor health, and harvest energy. The soft materials undergo large deformation in response to external stimuli, often leading to instability that is usually undesirable but sometimes useful. Here we study a dielectric elastomer membrane sandwiched between two soft conductors, rolled into a hollow tube, pre-stretched in the hoop direction, and fixed at the ends of the tube to two rigid rings. This structure functions as an electromechanical transducer when the two rings are subject to a mechanical force and the two conductors are subject to an electrical voltage. We formulate a computational model by using a variational principle, and calculate the large and inhomogeneous deformation by solving a nonlinear boundary-value problem. We demonstrate that large actuation strains are achievable when the height-to-radius ratio of the tube is small and the hoop pre-stretch is large. The model provides a tool to analyze various modes of instability and optimize the electromechanical performance.

Review of Soft Linear Actuator and the Design of a Dielectric Elastomer Linear Actuator

“…Teh et al [9] developed a cylindrical actuator, which significantly enlarged the electrically induced linear strains to 200%. Lu et al [10] conducted the theoretical analysis of cylindrical actuator and found out how the height-to-radius ratio of the tube and loading conditions affected the actuation. There also existed some cone-like (loudspeaker-type) linear DE actuators [11][12][13] which could generate a large deformation out of the membrane plane when actuating and stay in the plane without actuating.…”

Constitutive models of artificial muscles: a review

“…To prevent failure and to harness the large deformation of dielectric elastomers, it is necessary to construct a theoretical framework. Based on parameter analysis and loading design, many sensors (Jung et al, 2008;Son and Goulbourne, 2009;Gisby et al, 2013;Liu J.J. et al, 2015), actuators (Carpi and Rossi, 2004;Carpi et al, 2005;2007;Aschwanden and Stemmer, 2006;Plante and Dubowsky, 2007;Shankar et al, 2007;Wissler and Mazza, 2007;Biddiss and Chau, 2008;Moscardo et al, 2008;Kovacs et al, 2009;Liu et al, 2009b;Carpi et al, 2010;Fang et al, 2010;Akbari and Shea, 2012;Son et al, 2012;Giousouf and Kovacs, 2013;Haus et al, 2013;La and Lau, 2013;Shian et al, 2013;Hunt et al, 2014;Lu et al, 2014;Nguyen C.H. et al, 2014;Nguyen C.H.…”

Operational limits of a non-homogeneous dielectric elastomer transducer

“…Many DE configurations were proposed and studied. Some examples include equal-biaxial configuration [5], flat-clamped configuration [6], stacked configuration [7], tubular configuration [8], loudspeaker configuration [9] and parallelogram configuration [10].…”