Estimation of piezoelectric material properties by coupling theory and FEM

The performance of the finite element method (FEM) used for modeling ultrasound transducers depends on the accuracy of material properties. In the case where piezoelectric ceramic parameters are not available, the application of FEM to transducer design is very limited. A curve fitting method of estimating ceramic properties by coupling theory and FEM is described. The impedance of ceramic samples with various aspect ratios (width over thickness) were measured. The ceramic constants were adjusted in the FEM model to fit the experimental data. To reduce the number of degrees of freedom, a few of the key parameters, e.g., c₁₁, c₁₃, and c₃₃, were estimated from three samples by coupling theory. The sensitivity of the parameter variation to some special features of the impedance profile (e.g., f_s, f_p) were studied as a guideline for tuning the parameter value. Very good agreement between experiment and FEM over a wide range of aspect ratio (0.1-29) is obtained by this method