Optimization of load-driven soft dielectric elastomer generators

The performance of energy harvesting generators based on dielectric elastomers is investigated in this contribution. The amount of energy extracted by a four-step load-driven cycle is constrained by structural instabilities due to the loss of tension, the electric breakdown and the ultimate stretch ratio. To identify the optimal cycle complying with these limits, we formulate a constraint optimization problem proving the dependency of the generator performance on the ultimate stretch ratio and, moreover, a universal limit on the dielectric strength beyond which the optimal cycle is independent of this parameter. Thus, we reveal that there is an upper bound on the amount of harvested energy that depends only on the ultimate stretch ratio. (C) 2014 The Authors. Published by Elsevier B.V.