Damage imaging in a laminated composite plate using an air-coupled time reversal mirror

Journal Article · Tue Nov 03 00:00:00 EST 2015 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4935210· OSTI ID:1236773

Le Bas, P. -Y. ^[1]; Remillieux, M. C. ^[1]; Pieczonka, L.  ^[2]; Ten Cate, J. A. ^[1]; Anderson, B. E. ^[1]; Ulrich, T. J. ^[1]

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1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2. AGH Univ. of Science and Technology, Krakow (Poland)

We demonstrate the possibility of selectively imaging the features of a barely visible impact damage in a laminated composite plate by using an air-coupled time reversal mirror. The mirror consists of a number of piezoelectric transducers affixed to wedges of power law profiles, which act as unconventional matching layers. The transducers are enclosed in a hollow reverberant cavity with an opening to allow progressive emission of the ultrasonic wave field towards the composite plate. The principle of time reversal is used to focus elastic waves at each point of a scanning grid spanning the surface of the plate, thus allowing localized inspection at each of these points. The proposed device and signal processing removes the need to be in direct contact with the plate and reveals the same features as vibrothermography and more features than a C-scan. More importantly, this device can decouple the features of the defect according to their orientation, by selectively focusing vector components of motion into the object, through air. For instance, a delamination can be imaged in one experiment using out-of-plane focusing, whereas a crack can be imaged in a separate experiment using in-plane focusing. As a result, this capability, inherited from the principle of time reversal, cannot be found in conventional air-coupled transducers.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: LANL/LDRD; 2010-3/2; AC52-06NA25396
• OSTI ID: 1236773
• Alternate ID(s): OSTI ID: 1224929
• Report Number(s): LA-UR-15-26993; APPLAB
• Journal Information: Applied Physics Letters, Vol. 107, Issue 18; ISSN 0003-6951
• Publisher: American Institute of Physics (AIP)
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
36 MATERIALS SCIENCE
time reversal mirror
air-coupled imaging
nondestructive testing
elastic waves
ultrasonic transducers
Piezoelectric transducers
mirrors
ultrasonography