MODELING OF VIBRATIONS OF A STACKED PIEZO ELEMENT MADE OF POROUS PIEZOCERAMICS

Abstract

The work is devoted to a numerical study of the effectiveness of using porous piezoceramics in a stacked piezoelectric element, which can be used as a power drive element, a piezoelectric generator, or an ultrasonic emitter. The use of porous piezoceramics in stacked piezoelements has not received enough attention in the literature. The use of porous piezoceramics in stacked piezo elements has not received enough attention in the literature. The paper considers a stacked piezo element consisting of eight solid cylinders counter-polarized in the axial direction. The material of the cylinders is PZT-4 piezoceramic, the porosity of which varies from 0% to 80%. The problem of axial steady-state oscillations in the vicinity of the first resonance frequency and below it is solved. The lower end of the cylinder is fixed along the normal, excitation of oscillations is carried out by mechanical action under uniformly distributed pressure at the upper face or by the action of electric potential difference at the electrodes. The problems are solved in the framework of linear axisymmetric theory of electroelasticity. With mechanical action, the output characteristic of the device is the electrical potential of the free electrodes; with electrical action, it is the amplitude of the axial vibrations of the upper end or the reaction force if it is fixed. The finite element method implemented in the ACELAN package is used as the solution method. As a result of the numerical solution, the dependence of the percentage of porosity on the output characteristics of the piezo element is investigated: the frequencies of resonance and antiresonance, the electromechanical coupling coefficient, the output potential under mechanical loading, the amplitude of oscillations of the free upper end and the coupling reaction at its fixing when the oscillations are excited by the potential difference and the energy of the elastic element attached to this end. The analysis of the dependence of these characteristics allows us to conclude that it is reasonable to use such an element with porous ceramics as a piezoelectric generator and transmitter. It is noted that the choice of the percentage of porosity depends directly on the intensity of loads and the strength of porous piezoceramics.