Determination of Young’s modulus of the reduced layer of a piezoelectric RAINBOW actuator

Abstract

The reduced and internally biased oxide wafer (RAINBOW) actuator, a new type of monolithic piezoelectric bending device, is composed of a reduced electromechanically passive layer and an unreduced piezoelectric layer. The determination of the elastic properties of the reduced layer is important for optimizing actuator performance. In this paper, an analytical expression for bending resonant frequency is derived for the cantilever RAINBOW actuator by using composite beam theory. A resonance method is then described for determining Young’s modulus of the reduced layer of RAINBOW actuator. As a piezoelectric bending actuator, RAINBOW can be excited by its electromechanically active PZT layer without using any external excitation method. Young’s modulus can be calculated by measuring its resonant frequency, sample geometry, and densities of component parts. For comparison, the Young’s modulus is also determined by measuring the resonant frequency of a completely reduced plate with an external acoustic excitation method. The results obtained by these two excitation methods show good agreement.