Variation: Prestretch

The prestretch of the membrane is a very important parameter to influence the performance of dielectric elastomer actuators. When the dielectric membrane is prestretched, it decreases in thickness. Since the size of the Maxwell stress is determined by the electric field across the membrane (see Modeling section), smaller voltages are required to obtain the same Maxwell stress when the membrane is prestretched.

The more important influence of the prestretch on the actuation performance is that it moves the occurrence of electromechanical instability (see Modeling section) to larger strains or even completely removes it, so that larger strains are possible before failure.

The following figures show the results of a study that investigates the effect of prestretch on the performance of circular dielectric elastomer actuators:

design3.png

Prestretch 3x3

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Prestretch 4x4

design6.png

Prestretch 5x5

design7.png

(Strain after 900s as function of voltage for different prestrains)

Bibliography

Keplinger et al. (2012) Harnessing snap-through instability in soft dielectrics to achieve giant voltage-triggered deformation.

Keplinger et al. (2013) Stretchable, transparent, ionic conductors.

Koh et al. (2009) Maximal energy that can be converted by a dielectric elastomer generator.

Wissler and Mazza (2007) Mechanical behavior of an acrylic elastomer used in dielectric elastomer actuators.

Pelrine et al. (2001) Dielectric elastomers: generator mode fundamentals and applications.

Pelrine et al. (2000) High-Speed Electrically Actuated Elastomers with Strain Greater Than 100%.

Röntgen WC. (1880) Ueber die durch Electricität bewirkten Form—und Volumenänderungen von dielectrischen Körpern.

Suo, Zhigang (2010) Theory of dielectric elastomers.

Contributors

Philipp Rothemund