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An infrared-induced terahertz imaging modality for foreign object detection in lightweight honeycomb structure

An infrared-induced terahertz imaging modality for foreign insert detection in a glass fiber-skinned lightweight honeycomb composite panel
 
: Zhang, Hai; Sfarra, Stefano; Osman, Ahmad; Szielasko, Klaus; Stumm, Christopher; Genest, Marc; Maldague, Xavier P.V.

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IEEE transactions on industrial informatics 14 (2018), Nr.12, S.5629-5636
ISSN: 1551-3203
ISSN: 1941-0050
Englisch
Zeitschriftenaufsatz
Fraunhofer IZFP ()
terahertz; polynomial fitting; fourier transform; empirical orthogonal function; lightweight honeycomb

Abstract
In this paper, terahertz time-domain spectroscopy (THz-TDS) is used for the first time to detect fabricated defects in a glass fiber-skinned lightweight honeycomb composite panel. A novel amplitude polynomial regression (APR) algorithm is proposed as a pre-processing method. This method segments the amplitude-frequency curves to simulate the heating and the cooling monotonic behavior as in infrared thermography. Then, the method of empirical orthogonal function (EOF) imaging is applied on the APR pre-processed data as a post-processing algorithm. Signal-to-noise ratio analysis is performed to verify the image improvement of the proposed APR-EOF modality from a quantitative point of view. Finally, the experimental results and the physical analysis show that THz is more suitable with respect to the detection of defects in glass fiber lightweight honeycomb composites.

: http://publica.fraunhofer.de/dokumente/N-497390.html