Out-of-plane motion of a planar dielectric elastomer actuator with distributed stiffeners

A new design for a multi-layer dielectric elastomer actuator, reinforced with periodic stiffeners is presented. The resulting actuator enables complex out-of- plane motion without the need of the elastomer membrane prestretch. An in situ optical imaging system is used to capture the complex deformation pattern and track the non-planar displacement and curvature under the applied voltage. The role of the stiffeners periodicity, φ, on the macroscopic actuator response is analyzed numerically utilizing ABAQUS finite element software. A user-material subroutine is developed to represent the elastomer deformation under the applied electric field. It is found that the actuator force-stroke characteristics can be greatly changed by varying φ, while maintaining the same overall actuator stiffness. The numerical results showed a band of localized deformation around the stiffeners. The refinement of the stiffener, φ, increases the total actuated volume within the span of the actuator, and thereby the macroscopic actuator stroke. The stored elastic strain energy within the actuator is also increased. φ might be further refined down to the actuator sheet thickness, wherein the localized deformation bands overlaps. This is the practical limit of the stiffeners spacing to achieve the largest macroscopic actuator stroke. The developed experimental and modeling framework would enable the exploitation and optimization of different actuator designs to achieve a preset load-stroke characteristic.