Very high dielectric strength for dielectric elastomer actuators in liquid dielectric immersion

Abstract

This letter reported that a dielectric elastomer actuator (3M VHB), which is immersed in a liquid dielectric bath, is enhanced tremendously in dielectric strength up to 800 MV/m, as compared to 450 MV/m for the actuator operated in air. The bath consists of silicone oil (Dow Corning Fluid 200 50cSt), which is 6.5 times more thermally conductive than air, and it is found able to maintain the actuator at a stable temperature. As a result, the oil-immersed dielectric elastomer actuator is prevented from local thermal runaway, which causes loss of electrical insulation, and consequently avoids the damage by electromechanical instability. V

Electrode composition and partial discharges and their role in the breakdown of dielectric elastomer films

“…Since the temperature coefficient of resistivity is typically negative for polymeric dielectrics, this results in higher leakage currents and further heating. This behavior has been verified in dielectric elastomers [8], and actuator structures taking advantage of the thermal heatsinking afforded by dielectric oil being in contact with the elastomer have demonstrated higher breakdown fields [9], indicating thermal breakdown can be mitigated through good thermal management.…”

“…The bottom of the film is also powdered and connected to ground. Both the ground and HV electrode cables are insulated to prevent arc discharge It should be noted that when powdered carbon electrodes are used in this manner, this design is most similar to the structures used in [8], and so the oil bath would also be helping to prevent failure due to thermal runaway. In addition any particles lost into the castor oil are in a low stress region, so they will not affect the PD behavior unless the concentration increases uncontrollably.…”

Dielectric Elastomer Actuator for Soft Robotics Applications and Challenges

“…This uncertainty must be solved to guarantee a stable actuation system. As of now, methods of increasing the breakdown strength through prestretching, liquid dielectric immersion [158][159][160], or predicting the material's breakdown strength are being researched [160,161].…”

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.…”