Evaluation of Defect Detection in Aluminium, CFRP and Epoxy Resin Plates Using Non-contact Air-Coupled Ultrasonic Waves

In the field of aerospace materials and structures, water coupled ultrasonic testing was not desirable due to changes in properties and contamination reason. Therefore, in the present study non-contact air coupled ultrasonic transducers were proposed as an alternative examination for such applications. This present study describes our practical knowledge of using piezoelectric air-coupled transducers for visualization and defect identification of aluminium, CFRP and epoxy-resin specimens. Further, the effectiveness of the system is verified by experiments conducted in the inspection of artificial defects and 2D images was reconstructed through scanning of specific specimen surface. Results show that, all the created defects were identified successfully using C-scan technique. The measured defect values were compared with experimental defect values and shows good agreement. The 1 MHz piezoelectric transducer was the best for all the three specimens which is used in the present study because of the material structure being evaluated. The bulk wave piezoelectric transducer was identified as extensive pulse attenuation by the structure of the aluminium, CFRP and epoxy resin.