DYNAMIC POWER AND ENERGY CAPABILITIES OF COMMERCIALLY-AVAILABLE ELECTROACTIVE INDUCED-STRAIN ACTUATORS

A method has been developed to predict the apparent material constants , the input and output power and energy, and the electro-mechanical en ergy conversion efficiency of electroactive induced-strain actuators u nder full-stroke, quasi-linear dynamic operation. The effect of the pi ezo-electric counter electro-motive force on the apparent input admitt ance is included. The nonsymmetric expansion-retraction behavior of th e electro-active material under full-stroke dynamic operation is symme trized using a bias-voltage component and a superposed dynamic voltage amplitude that produce, in the actuator, a static position and a dyna mic stroke amplitude, respectively. It is shown that the presence of t he bias-voltage operation increases significantly the reactive power a mplitude, and a simple formula for estimating this increase is provide d. Reaction power values up to three times larger than those for unbia sed operation were found. The secant linearization method and vendor d ata were used to evaluate the full-stroke piezoelectric strain coeffic ient, d, elastic compliance, s, electrical permittivity, epsilon, and electro-mechanical coupling coefficient, kappa, of the electro-active actuator. Consistency with the basic active-material values was checke d, and correction of the actuator full-stroke electro-mechanical coupl ing coefficient was applied, when required. Maximum power and energy d elivery under optimal dynamic conditions (dynamic stiffness match) was studied, and the dynamic energy output capability of several commerci ally-available actuators were computed. Output energy densities per un it volume, mass, and cost were also calculated. The best electro-mecha nical conversion efficiency, which was shown to take place at stiffnes s ratios slightly different from the dynamic stiffness match, was also computed.