Electro-mechanical actuation modulates fracture performance of soft dielectric elastomers

Abstract

Soft dielectric elastomers respond to electric stimuli by undergoing large deformations and changes in their material properties. The actuation with deformable electrodes attached to the material originates Coulomb and dipole forces that convert the electric field into a mechanical response. Applications at large deformations can entail crack onset and propagation. Within this context, the response of a soft polymer to an applied electric field may serve to influence the fracture behavior of such materials, potentially enhancing it. Here we explore the fracture performance of an ultra-soft dielectric elastomer. To do so, we conduct tensile tests while applying electrical actuation on samples with pre-cuts. Additionally, we examine the elastomer filled with piezoelectric BaTiO3 particles to ameliorate the fracture performance beyond the limits observed in the unfilled material. In conjunction with the experiments, we employ a bespoke fracture phase-field model to analyze the stress triaxiality near the crack tip. The results indicate that the electric actuation induces beneficial crack tip blunting and stress de-concentration, enhancing the fracture toughness up to a 125% and delaying crack propagation. Our work provides a route for applications of soft dielectric elastomers that require improved fracture properties or, more broadly, the modulation of fracture behavior.