A variational constitutive framework for the nonlinear viscoelastic response of a dielectric elastomer

Kamran Khan, Husam Wafai, Tamer S. El Sayed

Research output: Contribution to journalArticlepeer-review

43 Scopus citations

Abstract

We formulate a variational constitutive framework that accounts for nonlinear viscous behavior of electrically sensitive polymers, specifically Dielectric Elastomers (DEs), under large deformation. DEs are highly viscoelastic and their actuation response is greatly affected in dynamic applications. We used the generalized Maxwell model to represent the viscoelastic response of DE allowing the material to relax with multiple mechanisms. The constitutive updates at each load increment are obtained by minimizing an objective function formulated using the free energy and electrostatic energy of the elastomer, in addition to the viscous dissipation potential of the dashpots in each Maxwell branch. The model is then used to predict the electromechanical instability (EMI) of DE. The electro-elastic response of the DE is verified with available analytical solutions in the literature and then the material parameters are calibrated using experimental data. The model is integrated with finite element software to perform a variety of simulations on different types of electrically driven actuators under various electromechanical loadings. The electromechanical response of the DE and the critical conditions at which EMI occurs were found to be greatly affected by the viscoelasticity. Our model predicts that under a dead load EMI can be avoided if the DE operates at a high voltage rate. Subjected to constant, ramp and cyclic voltage, our model qualitatively predicts responses similar to the ones obtained from the analytical solutions and experimental data available in the literature. © 2012 Springer-Verlag Berlin Heidelberg.
Original languageEnglish (US)
Pages (from-to)345-360
Number of pages16
JournalComputational Mechanics
Volume52
Issue number2
DOIs
StatePublished - Nov 10 2012

ASJC Scopus subject areas

  • Computational Theory and Mathematics
  • Computational Mathematics
  • Mechanical Engineering
  • Ocean Engineering
  • Applied Mathematics

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