Electromechanical Admittance Signature Analysis of Piezo-ceramic Transducers for NDE

Abstract

Of the multiple applications of the piezoelectric ceramics transducers such as Lead-Zirconate-Titanate (PZT), one prominent one is in the field of non-destructive evaluation (NDE) using the Electromechanical Impedance method (EMI). In this method a piezo-ceramic transducer (PZT) is bonded on to the structure and actuated using a harmonic voltage at ultrasonic frequency ranges. The dynamics of the PZT-structure interaction is captured in the frequency response of the electrical admittance of the PZT, popularly called as the admittance signature. A mechanical damage in the structure alters the mass, stiffness and damping properties locally, which in turn alters the admittance signature. Many analytical and semi-analytical models of the EMI method that have been used are limited in application to simple systems. The coupled-field finite element modeling has been demonstrated to quite accurately predict the admittance signatures as obtained by the experimental EMI technique. This paper presents the results of identification and quantification studies of damage using the analysis of admittance signatures obtained by coupled-field FE model of a simple cantilever type plate in ANSYSTM.