A Method for the Automatic Characterization of Piezoelectric Ceramic Elements

The routes to perform the characterization of piezoelectric resonators are published in IEEE and IEC Standards. The basis of the standards is the existence of well–defined modes that are been analytically solved. The development of piezoelectric resonator Finite Element Models (FEM) opens the possibility of characterizing elements with geometries different from those recommended in the Standards. In this paper an automatic procedure for the characterization of piezoceramic elements, based on the use of the ANSYS commercial code, is described. The procedure is based on the measurement of the electrical input impedance (Zim) of the sample to characterize; the obtained result is compared with the ANSYS simulation result, performed by using the material parameters in the manufacturer data sheet. The characterization fitting procedure is performed by a non linear fitting method that recursively adjusts the material parameters, until the computed impedance coincides with the experiment. The method was applied to a 1–D rod element, to a thin disk and to a 2–D square element; in all cases the material parameters were computed with a very good agreement between FEM and experiment. The proposed procedure permits the characterization of materials when the manufacturing procedure does not allow the fabrication of the shapes recommended by the Standards.