Thermodynamic model using experimental loss factors for dielectric elastomer actuator design

Abstract

Dielectric Elastomer Actuators (DEAs) are a promising actuation technology for mobile robotics due to their high forceto- weight ratio, their potential for high efficiencies, and their low cost. The preliminary design of such actuators requires a quick and precise assessment of actuator energy conversion performance. To do so, this paper proposes a simple thermodynamic model using experimentally acquired loss factors that predict actuator mechanical work, energy consumption, and efficiency when operating under constant voltage and constant charge modes. Mechanical and electrical loss factors for both VHB 4905 (acrylic) and Nusil's CF19-2186 (silicone) are obtained by mapping the performances of cone-shaped DEAs over a broad range of actuator speeds, capacitance ratios, and applied voltages. Extensive experimental results reveal the main performance trends to follow for preliminary actuator design, which are explained by the proposed model. For the tested conditions, the maximum experimental brake efficiencies are ~35% and ~25% for VHB and CF19-2186 respectively.