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

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 ofmore » time reversal, cannot be found in conventional air-coupled transducers.« less
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  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. AGH Univ. of Science and Technology, Krakow (Poland)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0003-6951; APPLAB
Grant/Contract Number:
LANL/LDRD; 2010-3/2; AC52-06NA25396
Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 107; Journal Issue: 18; Journal ID: ISSN 0003-6951
American Institute of Physics (AIP)
Research Org:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Org:
Country of Publication:
United States
42 ENGINEERING; 36 MATERIALS SCIENCE time reversal mirror; air-coupled imaging; nondestructive testing; elastic waves; ultrasonic transducers; Piezoelectric transducers; mirrors; ultrasonography