Exfoliation detection using structurally integrated piezoelectric ultrasonic transducers

Advanced sensors and sensor network technologies are shaping the future of civilian and military air platform health assessment and monitoring. In this paper, the feasibility of applying a structurally integrated thick-film piezoelectric ceramic ultrasonic transducer for monitoring exfoliation corrosion damage is investigated. The ultrasonic transducer can easily and reliably be deposited on metallic and polymeric structures using a sol-gel spray approach. The change in material thickness due to exfoliation damage is estimated using ultrasonic time-of-flight measurements. Experimental results from two aluminium (Al.7075-T6511) specimens are presented. In comparison, conventional water-coupled ultrasonic tests were also conducted to generate a thickness map for each selected specimen before the integrated transducers were fabricated. Close correlation was obtained between both conventional and integrated thick-film ultrasonic measurements, demonstrating the effectiveness of the integrated thick-film ultrasonic transducer for exfoliation corrosion damage assessment and monitoring.