Effects of off-plane deformation and biased bi-axial pre-strains on a planar contractile dielectric elastomer actuator

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Abstract

Dielectric elastomers are in a special class of electro-active polymers known for generating expansion in plane and contraction in thickness under voltage application. This paper advancesthe understanding of a planar contractile dielectric elastomer actuator (cDEA) that is distinctfrom conventional multi-layer cDEAs but generates comparable contractile strains. Its structure has a rod-constrained rhombus-shaped electrode region, which undergoes simultaneous in-plane contraction and extension during actuation depending on the configuration of the rod-constraining. It is demonstrated that when the planar cDEA is driven by high voltages, off-plane deformation (i.e., wrinkling) in the direction of contraction causes the rod-constrained electrode region to lose
tension and extend in the lateral direction, resulting in a significant increase in contraction strain. It also demonstrates that the contraction strain can be increased further by having biased bi-axial pre-strains. By incorporating both effects, the new cDEA generates a maximum contraction strain of 13%, twice that reported previously for planar cDEAs. A modified planar cDEA, having an additional rigid frame to maintain the pre-strain in the lateral direction to contraction was also developed to demonstrate contractile force actuation. Finally, a stability study shows that the planar cDEA has a primary failure mode of electrical breakdown close to the corners of the rod-constrained electrode
region. Having inactive regions around the active cell is essential for generating contraction and eliminating buckling of the planar cDEA in the lateral direction.
Original languageEnglish
Number of pages18
JournalActuators
Publication statusAcceptance date - 29 Oct 2018

Keywords

  • DEA
  • topological optimization
  • pre-strain
  • fibre enforcement
  • rod-pre-strain
  • planar cDEA

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