Theoretical study of the electromechanical efficiency of a loaded tubular dielectric elastomer actuator

The electromechanical efficiency of a loaded tubular dielectric elastomer actuator (DEA) is investigated theoretically. In previous studies, the external system, on which the DEA performs mechanical work, is implemented implicitly by prescribing the stroke of the DEA in a closed operation cycle. Here, a more generic approach, modelling the external system by a frequency-dependent mechanical impedance which exerts a certain force on the DEA depending on its deformation, is chosen. It admits studying the dependence of the electromechanical efficiency of the DEA on the external system. A closed operation cycle is realized by exciting the DEA electrically by a sinusoidal voltage around a bias voltage. A detailed parametric study shows that the electromechanical efficiency is highly dependent on the frequency, amplitude, and bias of the excitation voltage and the mechanical impedance of the external system as well. Efficiencies of up to 93% can be observed for the Danfoss PolyPower tubular DEA if the mechanical impedance of the external system is adjusted to the mechanical impedance of the DEA or vice versa. The study shows that a tubular DEA can be dimensioned and operated such that it performs most efficiently for a given application.