DYNAMICALLY RECONFIGURABLE PIEZOELECTRIC SENSORS FOR ULTRASONIC NONLINEARITY MEASUREMENTS

Ultrasonic interaction with fatigue damage in a material can lead to nonlinear ultrasonic harmonic generation. Unfortunately, nonlinear generation is often very weak and measurement sensors need to have a large dynamic range to pick weak second harmonic signals. Furthermore, couplant dependence of the ultrasonic measurements can mask any variations in second harmonic generation due to fatigue damage. To overcome this, a couplant-independent method for ultrasonic nonlinearity measurements was recently proposed by us. This method requires two sets of transducers that can each generate/detect both the fundamental and second harmonic signals. In this paper, we describe a dynamically reconfigurable interdigitated Sur-face Acoustic Wave transducer that can effectively be used to generate/receive both the fundamental and the second harmonic signals. This is achieved using simple external electronic reconfiguration of the signals from a pair of interdigitated transducer arrays.