SIMULATION AND MODELLING OF AE SENSORS FOR CHARACTERIZATION OF ELECTRICAL PARAMETERS

Abstract

Acoustic Emission Analysis (AEA) is becoming increasingly popular among various Nondestructive Testing (NDT) techniques. Piezoelectric type sensors are widely used for Acoustic Emission (AE) measurements. A piezoelectric type AE sensor mainly consists of a piezoelectric element and a non-piezoelectric backing layer. The backing layer presents acoustical loading to the piezoelectric element. The material properties and physical properties of these elements decide the performance of the sensor and l~ence the suitability of a particular sensor for a particular application. A comprehensive modelfor AE sensors is presented which combines Mason's model for piezoelectric element in thickness mode and acoustic transmission line model for backing element This AE sensor model is analyzed to derive expressions for electrical impedance, pressure sensitivity, velocity sensitivity and displacement sensitivity of an AE sensor. A simulation program using MATLAB has been developed to generate impedance and sensitivity characteristics of the sensor. Further, a finite element model of AE sensor has been developed using commercial finite element software ANSYS to generate same performance characteristics of AE sensor. The characteristics obtained as the results of the two programs were compared and found to be matching with each other. This theoretically verified that the model and simulation results obtained using MATLAB program are accurate. Such a program can be useful for predicting performance characteristics of an AE sensor without actually fabricating the sensor and thus simplifying the sensor design process.