Design and characterization of an actively deformable shell structure composed of interlinked active hinge segments driven by soft dielectric EAPs

Active shell structures with large out-of-plane displacement potential may be used to generate an interaction between the structural shape and the environment. Among the electroactive polymers (EAPs), in particular, the soft dielectric EAPs represent a promising technology to drive shell actuators due to their huge active strain potential and intrinsic compliance.This paper presents a shell actuator based on soft dielectric EAPs, which can actively take complex, single-curved shapes. The actuator is composed of seven interlinked active hinge segments, where the pre-strained dielectric films are arranged in an agonist–antagonist configuration. The soft dielectric EAP films, which act as an active skin, are thereby mounted to a hinged mechanical backbone structure.A computer-controlled system for the individual supply of the agonist–antagonist segments is proposed, where the DC high voltages provided by only one single HV amplifier is consecutively switched in a repeated loop to the active hinge segments.The experimental characterization included, on the one hand, the quasi-static full angular displacement potential of the shell actuator. Angles of displacement exceeding 90° back and forth at the free end of the actuator were observed. On the other hand, we examined the dynamic behaviour of the shell actuator under phase-shifted sinusoidal activation of the hinge segments. As expected, the actuator displayed an “organic” propagation of transversal displacement waves along its principal axis (similar to the swimming motion of fish).