Using d15 Piezoelectric Transducers for Ultrasonic Inspection of Delamination in Laminated Structures

Abstract

A laminated beam consisted of internally embedded d15 piezoelectric transducers in a pitch-catch configuration was fabricated with artificial delamination created at the interface of aluminum layers. The severity of damage was also varied to evaluate the effectiveness of the approach to detect delamination. A five-peak tone burst signal centered at 30 kHz was supplied to piezoelectric actuators throughout the experiment to produce antisymmetric waves in the laminate specimen. It was found that the closer the delamination occurred to the d15 PZT actuator the greater the change in signal increasing the probability to be identified using antisymmetric A0 wave mode. The analysis suggests that d15 PZT actuators should be placed in regions where delamination is likely to occur in laminated structures. Also, the propagation path of delamination was successfully predicted using a set of sensor signals processed using damage index methods including Pearson correlation coefficient and root mean square deviation. Evaluation of the results indicated that embedded d15 piezoelectric transducers exclusively couple to antisymmetric guided waves and can advance signal analysis for detection of delamination with ultrasonic structural health monitoring systems.