Time-frequency analysis of pulsed eddy current signals

Detection and measurement of the material loss due to corrosion in aircraft fuselage lap splices are of great importance to life management of ageing aircraft. Pulsed eddy current (PEC) techniques have shown the potential to fully characterise these structures. However, variations in the probe lift-...

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Bibliographic Details
Published in:Journal of nondestructive evaluation 2001-06, Vol.20 (2), p.73-86
Main Authors: SAFIZADEH, M. S, LEPINE, B. A, FORSYTH, D. S, FAHR, A
Format: Article
Language:English
Subjects:
Computers in experimental physics
Condensed matter: structure, mechanical and thermal properties
Cross-disciplinary physics: materials science
rheology
Exact sciences and technology
Image processing
Instruments, apparatus, components and techniques common to several branches of physics and astronomy
Materials science
Materials testing
Mechanical and acoustical properties of condensed matter
Mechanical properties of solids
Nondestructive testing: electromagnetic testing, eddy-current testing
Physics
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Summary:Detection and measurement of the material loss due to corrosion in aircraft fuselage lap splices are of great importance to life management of ageing aircraft. Pulsed eddy current (PEC) techniques have shown the potential to fully characterise these structures. However, variations in the probe lift-off, the interlayer gaps and material thinning produce similar PEC signals, making signal interpretation very difficult. This paper describes time-frequency analysis algorithms applied to pulsed-eddy current signals from lap-joint specimens containing simulated flaws. The effect of probe lift-off, interlayer gap, and material thinning on PEC signals is examined in three-dimensional space (amplitude-time-frequency). This study shows that the time-frequency analysis of PEC signals provides specific visual patterns that can be related to the interlayer gap, lift-off, and material loss. (Material: aluminum alloy lap joint.)
ISSN:0195-9298
1573-4862
DOI:10.1023/A:1012244208475