Introduction

The discovery of piezoelectric phenomena in 1880 led science and technology into a new dimension. It has been over one hundred and twelve years (1880–1992) since the first observation of piezoelectric phenomena by the Curie brothers. Over the years, sophisticated piezoelectricity theories were proposed and refined; new piezoelectric materials were discovered or synthesized (Mason, 1950; Cady, 1964; Mindlin, 1961&1972; Tiersten, 1969; Sesseler, 1981; Dökmeci, 1983; Tzou & Zhong, 1990; etc.). Novel piezoelectric devices were invented and applied to a variety of engineering applications (Mason, 1981; Sessler, 1981; Dökmeci, 1983; Tzou, 1990&1992b; Tzou & Fukuda, 1992). In the recent development of active adaptive structures and micro—electromechanical systems, active piezoelectric and elastic/piezoelectric structures (elastic materials integrated with piezoelectric sensors/actuators and control electronics) and thin—layer piezoelectric devices are very promising in both static and dynamic applications, e.g., aerospace/aircraft structures, robot manipulators, vibration controls and isolations, high—precision devices, micro—sensors/actuators, thin—film micro—electromechanical systems, micro—displacement actuation and control, etc (Tzou & Fukuda, 1991&1992). All these activities have driven a renewed and widely spread interest in piezoelectricity related researches and developments.