Design and characterization of an active hinge segment based on soft dielectric EAPs

This paper presents an active hinge configuration driven by soft dielectric EAPs, which is able to perform specific rotary motions back and forth. The active structure is composed of a hinged support structure to which from both sides pre-strained dielectric elastomer (DE) films are attached. The resulting structure is similar to a biological agonist–antagonist configuration. Based on a hyperelastic model for the dielectric film the design of the active hinge segment was optimized to achieve the best overall performance in terms of the angle of displacement of the free segment and the blocking force of the constrained segment, respectively. In experimental tests the blocking force and the free angle of deflection of active hinge segments with different setups were characterized. The effects from asymmetrical and symmetrical pre-straining of the DE films as well as from stacking of several DE film layers were investigated. Fairly good agreement between the modelling and the experiments was found. In addition, the durability of the active hinge samples under cyclical activation was experimentally determined. Typically, rather few activation cycles were endured before a dielectric breakdown occurred.