Electromechanical stability in charge-controlled dielectric elastomer actuation

Deformation of dielectric elastomer under a voltage load is large but is limited by the pull-in instability. A recent experiment showed that by spraying charges on the dielectric, a large deformation is obtained without pull-in. We propose a thermodynamic model to describe the electromechanical stability of charge-controlled actuation, with particular emphasis on the electrostatic energy created by constant charges and its coupling with the deformation. We examine the electrostatic stress induced by charges and compare it with the Maxwell stress. The mechanism in the stabilization when spraying charges is interpreted and is different from the previous conclusion on strain-stiffening. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3670048]