Corrosion of aircraft aluminium lap joints is a major problem that can affect maintenance costs and structural integrity. The thickness loss due to corrosion reduces the residual strength and fatigue life of lap joints. Ten percent material loss is the maximum corrosion level that can generally be tolerated in the large transport aircraft; beyond that replacement or repair is often required. A question has been raised by those in the industry concerning the reliability of test methods that are used to detect corrosion that results in 10 % material loss. In this paper, different nondestructive testing technologies available for detection and measurement of hidden corrosion in lap joint structures were tested. Ultrasonic testing, eddy current testing at four frequencies and pulsed eddy current testing were used. Also, two postprocessing approaches based on data fusion and signal processing were assessed. These techniques were applied to a real aircraft lap joint section that contained different levels of corrosion. The C-scan images of each technique provided the information necessary to compare the capability of the techniques using the root mean squared error and probability of detection analysis. Ultrasonic testing had the best resolution but only for the first layer of a multilayer structure. Although the pulsed eddy current test slightly overestimated the thickness loss in two layer structures, it provided the best overall results. The data fusion of pulsed eddy current and eddy current results can improve the results of any of these techniques alone, but it needs at least two C-scans of the specimen. The optimal rnixing of multifrequency eddy current data also provides a better estimation of thickness loss when compared to the data obtained by the conventional eddy current alone.


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    Titel :

    Evaluation of NDT techniques for corrosion detection and quantification in lap joints


    Weitere Titelangaben:

    Bewertung von ZfP-Verfahren zum Nachweis und zur Quantifizierung von Korrosion in Überlappstößen


    Beteiligte:
    Safizadeh, M.S. (Autor:in) / Forsyth, D.S. (Autor:in) / Liu, Z. (Autor:in) / Fahr, A. (Autor:in)

    Erschienen in:

    Materials Evaluation ; 66 , 5 ; 501-506


    Erscheinungsdatum :

    2008


    Format / Umfang :

    6 Seiten, 9 Bilder, 1 Tabelle, 8 Quellen



    Medientyp :

    Aufsatz (Zeitschrift)


    Format :

    Print


    Sprache :

    Englisch





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