Ultrasonic evaluation of dispersive polymers by the piezoelectric embedded element method: modeling and experimental validation

Abstract

In this paper, a one-dimensional model for the frequency evolution of the electric impedance of a thin piezoelectric disk is derived. It is established that this impedance depends on the acoustical properties of the surrounding media. The validity of such a model is improved by comparing theoretical calculations with experimental electrical impedance measurements obtained when the piezoelectric element is bounded between two dispersive plates, parallel faced and of finite thickness. By means of this model, the inverse problem consisting of determining the acoustical properties of the surrounding media from an electrical impedance measurement of the embedded sensor is solved. This is achieved through a nonlinear optimization numerical method. The corresponding results are successfully compared with those obtained by ultrasonic spectroscopy.