Piezoelectric devices and their application in smart structures

Abstract

Piezoelectric materials are the main functional materials for sensors and actuators in smart structures. In this paper, two new types of piezoelectric devices, functionally graded (FG) piezoelectric bending actuators and piezoelectric fibers with metal core, and their applications in smart structures are introduced. A new process to fabricate piezoelectric ceramic fibers of 150 mum to 250 mum in diameter with metal cores of 50 mum in diameter has been developed. Since the metal core can be used as an electrode, a single fiber can be used as sensor or an actuator after the other electrode is coated on the outer surface of the fiber. After being poled, the fiber can be used as a sensor or an actuator. The fundamental electromechanical characteristics of the fibers are investigated and an example of application as Lamb wave sensors is introduced. The fabrication process of functionally graded piezoelectric bending actuators and the characteristics of the fabricated actuators are introduced. The material compositions with different dielectric and piezoelectric constants were selected. The durability of the fabricated FG piezoelectric actuators was measured in a vibration test and compared with that of the traditional bimorph actuator to evaluate the improvement of performance. The results show that the durability of the FG piezoelectric actuators is much higher than that of the bimorph actuator.