An investigation of the tertiary coupling effect under the longitudinal mode of a piezoelectric crystal

Abstract

In this article, multiple piezoelectric effects are investigated on the basis of the classical piezoelectric theory. The objective reality of multiple piezoelectric effects is elucidated from theoretical analysis first. Based on four kinds of piezoelectric equations, the relationship between the generation of multiple piezoelectric effects and boundary conditions is analysed, the process of their generation is elaborated, and the formulae of the tertiary piezoelectric effect are deduced. Then, the experimental results of the tertiary coupling effect are obtained under the longitudinal mode of a PZT-5 stack by the methods that are equivalent to changing boundary conditions. Experimental data show that the output of the tertiary direct and converse piezoelectric effect is also linear with the applied force and voltage, respectively. However, the output directions are opposite to that of the primary piezoelectric effect. The theoretical analysis is justified by experimental results and the experimental methods presented are proved to be scientific and feasible. Moreover, the influence of the tertiary piezoelectric effect on the piezoelectric coefficient and the performance of sensors and actuators is further analysed. The study of multiple piezoelectric effects provides a new method for the improvement of the performance of piezoelectric sensors and actuators.