STRESSING ISSUE OF A PIEZOCERAMIC CANTILEVER WITH LONGITUDINAL POLARISATION AND ELECTRODE COATINGS

The main subject of this study is the investigation of the free vibration of a rectangular prismatic piezoceramic cantilever with longitudinal polarization and electrode coatings. Based on the general solution of coupled equations for piezoceramic material, applying the equations of electro-elasticity and satisfying electrical and mechanical conditions for the stress of a cantilever made from PZT4 piezoceramic material, componential displacements, electric potential, specific strain, electric field, and piezoelectric displacement, are determined and numerically obtained with Matlab software package. Based on the obtained equations and simulation results, it is possible to optimize the dimensions of the cantilever and determine the type of piezoceramic.

Effective properties of a porous inhomogeneously polarized by direction piezoceramic material with full metalized pore boundaries: Finite element analysis

This paper concerns the homogenization problems for porous piezocomposites with infinitely thin metalized pore surfaces. To determine the effective properties, we used the effective moduli method and the finite element approaches, realized in the ANSYS package. As a simple model of the representative volume, we applied a unit cell of porous piezoceramic material in the form of a cube with one spherical pore. We modeled metallization by introducing an additional layer of material with very large permittivity coefficients along the pore boundary. Then we simulated the nonuniform polarization field around the pore. For taking this effect into account, we previously solved the electrostatic problem for a porous dielectric material with the same geometric structure. From this problem, we obtained the polarization field in the porous piezomaterial; after that, we modified the material properties of the finite elements from dielectric to piezoelectric with element coordinate systems whose corresponding axes rotated along the polarization vectors. As a result, we obtained the porous unit cell of an inhomogeneously polarized piezoceramic matrix. From the solutions of these homogenization problems, we observed that the examined porous piezoceramics composite with metalized pore boundaries has more extensive effective transverse and shear piezomoduli, and effective dielectric constants compared to the conventional porous piezoceramics. The analysis also showed that the effect of the polarization field inhomogeneity is insignificant on the ordinary porous piezoceramics; however, it is more significant on the porous piezoceramics with metalized pore surfaces.

Study on some Behavioral Particularities of the Piezoceramic Elements from the Ultrasonic Converter Construction

The ultrasound processing is in continuous development, always bringing better technological solutions. Ultrasonic welding occupies an important place within this category of processing. The present study focuses on some piezoceramic materials that represent the active elements in the structure of the required energy generator on which ultrasonic welding is based in fact. Using the analytical method of investigation, several aspects of piezoceramic material structural behavior during the exploitation were followed, both at macroscopic and microscopic level. Some causes and effects of changes to their functionality have been analyzed. The paper concludes with observations and recommendations on optimizing the manufacture and use of piezoceramic materials intended for converter construction for ultrasonic welding.