<title>Comparison of solid state actuators based on power and energy criteria</title>

Abstract

A study of published literature and vendor information about solid-state induced-strain actuators has been undertaken to establish their dynamic-operation mechanical and electrical characteristics, and to compare their output power and energy density criteria. A theory was developed from first principles to predict the input and output power and energy amplitudes under dynamic operation including the piezo-electric counter electro-motive force and the bias- voltage effects. The effective electro-mechanical coupling coefficient, k, for an assembled active-material stack was calculated from vendor data using a remarkably simple formula. Values between 0.45 and 1.038 were found, somehow in disagreement with the generally accepted value of 0.7 for the basic material. Dynamic energy output at the optimal stiffness match condition was found to have values of up to 0.260 J for some off-the-shelf actuators. Dynamic energy density per unit volume and unit mass varied in the range 0.5 - 3.7 J/dm3 and 0.058 - 0.482 J/kg, respectively. Conversion efficiency between input electrical power and output mechanical power was found to vary widely in the range 3.74% - 32.39%. This paper presents, with priority, two remarkably simple formulae: one for calculating the effective electro-mechanical coupling coefficient, K, using standard vendor data; the other for estimating the peak reactive power for bias-voltage operation of the actuator.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.