Engineering Institute Seminar: Application of Ultrasonic Propagation Imaging Technology to

Speaker: Jung-Ryul Lee, Ph.D., Department of Aerospace Engineering, Chonbuk National University, South Korea

Abstract: The seminar will present application of in-plane ultrasonic propagation imaging (UPI) system to aircraft, wind turbine, and power plant structural health management. The ultrasonic imaging system being operated in pitch-catch mode consists of a Q-switched laser, laser mirror scanner, and ultrasonic receiver. Laser beam focusing is not necessary and one fixed point ultrasonic sensing is carried out by an integrated, contact, or noncontact sensor. When a laser optical pulse impinges the surface of the target, an ultrasonic wave is created at the affected point. The wave is propagated over the target and reaches the ultrasonic sensing point. Three novel image processing technologies for damage detection and evaluation have been incorporated into the in-plane UPI system, referred to as ultrasonic wave propagation imaging (UWPI), ultrasonic frequency tomography (UFT), and ultrasonic energy propagation imaging (UEPM). In UWPI, damages are detected in the form of scattered wavefields. UFT maps tomograms slicing the frequency component of the waves obtained by the scanning. Any anomaly in the target structure that gives rise to a wave with a changed frequency can be seen in the tomogram with the same frequency as relatively high ultrasonic amplitude concentrated at the location of anomaly. Contrast to the UFT, the UEPI conserves the time information and facilitates frequency selection during the result processing. The result of UEPI can be shown as an ultrasonic energy wavefield emerging from the sensing location. The wavefield propagation is intuitively understandable hence it is suitable even for complex structures. To demonstrate the system robustness as a ground health management system, thick flat and curved skins and a fighter jet pod quartz/epoxy radome with honeycomb core were inspected by combining with PZT sensors integrated in their inner surfaces. To demonstrate the system feasibility as a fast automatic nondestructive inspection system for power plant structures, flow accelerated corrosion inside an elbow pipe and inner cracks in a pipe weld joint were detected by combining a PZT sensor bonded and a fiber guided acoustic wave (FAW) PZT sensor welded on their outer surfaces. As a challenging application, disbond in leading edge specimen of a wind turbine blade was inspected at 40 m by long-distance in-plane UPI system.

Biography: Jung-Ryul Lee is an assistant professor of the Aerospace Department at the Chunbook National University, South Korea, where he joined in 2007. He received his MS from KAIST in Korea, and Ph.D from Ecole Nationale Superieure Des Mines De Saint-Etienne with the 1st class honor in 2004. Before joining the university, he has been a staff member at the National Institute of Advanced Industrial Science and Technology in Japan. His research interest includes integrated structural health & usage monitoring, fiber optic sensors & systems, advanced NDE, and laser-induced ultrasound and plasma. He has published over 100 articles in this area, and received several awards, including 2007 Emerging Researcher Award by the Japanese Society for Nondestructive Inspection.

The flyer for this event is available here.

Contact Kathie Womack @ 663-5206 or email womack@lanl.gov for further information. Seating is limited. Please RSVP by Monday, November 16, 2009.