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Advanced ultrasound activated Lockin-Thermography for defect selective depth resolved imaging

Gleiter, A. and Riegert, G. and Zweschper, Th. and Degenhardt, R. and Busse, G. (2006) Advanced ultrasound activated Lockin-Thermography for defect selective depth resolved imaging. 28th Thermosense Conference, 2006-04-17 - 2006-04-20, Orlando, Florida (USA).

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Abstract

Ultrasound activated Lockin-Thermography („ultrasound attenuation mapping“) is a defect selective NDT-technique. Its main advantage is a high probability of defect detection since only defects produce a signal while all other features are suppressed. The mechanism involved is local sound absorption which turns a variably loaded defect into a heat source. Attenuation of elastic waves in a solid due to internal mechanical losses was reported for the first time in 1979 by Henneke and colleagues for continuous and pulsed ultrasound injection. Later, amplitude modulated ultrasound was used to derive frequency coded phase angle images combining defect-selectivity with robustness of measurement. With mono-frequent ultrasound excitation a standing wave pattern might hide defects. With additional modulation of the ultrasound frequency such a misleading pattern can be minimized. Applications related to quality maintenance (aerospace, automotive industry) will be presented in order to illustrate the potential of frequency modulated ultrasound excitation and its applications.

Document Type:Conference or Workshop Item (Paper)
Title:Advanced ultrasound activated Lockin-Thermography for defect selective depth resolved imaging
Authors:
AuthorsInstitution or Email of Authors
Gleiter, A.Institute of Polymer Testing and Polymer Science, Department of Non-Destructive Testing
Riegert, G.Institute of Polymer Testing and Polymer Science, Department of Non-Destructive Testing
Zweschper, Th.Institute of Polymer Testing and Polymer Science, Department of Non-Destructive Testing
Degenhardt, R.UNSPECIFIED
Busse, G.Institute of Polymer Testing and Polymer Science, Department of Non-Destructive Testing
Date:2006
Keywords:Lockin-Thermography, Sonic Thermography, Ultrasound Thermography, Attenuation Mapping, Defect Selective NDT, dark field method
Event Title:28th Thermosense Conference
Event Location:Orlando, Florida (USA)
Event Type:international Conference
Event Dates:2006-04-17 - 2006-04-20
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Aeronautics
HGF - Program Themes:Aircraft Research
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Structures & Materials
Location: Braunschweig
Institutes and Institutions:Institute of Composite Structures and Adaptive Systems
Deposited By: Doris Ries
Deposited On:21 Apr 2007
Last Modified:27 Apr 2009 13:34

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