Investigation of a multi-element focused air-coupled transducer.

This paper presents the results of a numerical simulation and experimental test of a multi-element focused air-coupled transducer. The experimental structure of each transducer element comprises 1-3 connectivity piezo-composite stacking with two matching layers to overcome the enormous impedance mismatch between the piezo-composite disc and air. The numerical simulation is carried out using the circular-piston radiation model, and the experimental results for the acoustic field agree well with the simulation results. Furthermore, surface microcracks are detected successfully using a C-scan system involving the designed multi-element focused air-coupled transducer. The results show that the designed multi-element focused air-coupled transducer offers excellent focusing ability and is beneficial for detecting surface microcracks. [ABSTRACT FROM AUTHOR]