Invited Research Lecture: Air-coupled Ultrasonic NDE - Principles and Applications

Date: 19 May 2009 - 19 May 2009

Venue: SIMTech Auditorium, Tower Block, Level 3


Conventional ultrasonic Nondestructive Evaluation (NDE) typically requires a coupling medium in the form of liquid or gel.  This requirement poses problems in the inspection of perforated structures like engine necelles with acoustic control and materials that are intolerant to wetting or contamination, such as green ceramics, foam, wood, and paper products.  Non-contact, air-coupled ultrasound therefore has a distinct advantage and can therefore facilitate simpler field applications.  Technological development over the last two decades has made air-coupled ultrasound an increasingly useful tool for nondestructive testing of materials and structures. This presentation will review the basic physical principles involved in air-coupled ultrasonic transmission and the state-of-the-art in air-coupled transducers and instrumentation. A number of application examples of NDE using air-coupled ultrasound will be described.  Capabilities of air-coupled ultrasound in the manufacturing environment and for field inspection will also be described.  

About the Speaker
Prof David K Hsu is a Senior Scientist at the Center for Nondestructive Evaluation and an Adjunct Professor of Aerospace Engineering at Iowa State University. He holds a PhD in Physics from Wayne State University in 1971. He has been actively involved in NDE research at ISU since 1984. His main research interests are ultrasonics, NDE, and composite materials. He has developed special ultrasonic transducers with Gaussian and Bessel Beam profiles, a fieldable ultrasonic scanner (the "Dripless Bubbler") for detecting corrosion on aircraft, the Computer Aided Tap Tester (CATT) for inspecting composites, and a fieldable air-coupled ultrasonic scanner. The Dripless Bubbler received an R&D100 award and both the CATT and the Dripless Bubbler have been commercialised. His current research area includes NDE for composite repairs, degradation damage of composites and the application of air coupled ultrasound. Prior to ISU, he taught physics in the Department of Physics at Colorado State University where he did research on nuclear acoustic resonance in metals and alloys and studied the properties of metal hydrides. He has published more than 250 papers and holds seven US patents.

10.30am    Registration

10.45am    Presentation by Prof David Hsu

11.45am    End

Who Should Attend
Research scientists, engineers, industry professionals, academic experts, engineering and science students.

Registration for the lecture is free of charge. Seats are available on a first-come, first served basis.

For technical enquiries, please contact Dr Sim Lay May, Precision Measurements Group, Email:
For general enquiries, please contact Alice Koh, Email: