In damage detection algorithms the use of mode-force error arising from reduced analytical system matrices precludes the possibility of stiffness damage localization for those elements residing entirely outside the analysis set. Subsequently, any indication of mode-force error arising from damage appears as a force imbalance in each reduced degree of freedom due to the erroneous load paths introduced in the reduction process. The result is a smearing of the otherwise localized nature of the error thereby altering the interpretation of perturbation matrix-based damage detection results. To address this issue this work seeks to reconcile the inherent dimensional mismatch between finite element models and incomplete measured modal data by use of a subspace recognition procedure based on the problem of subset selection. The spatial characteristics of the reduced dynamic residual are assumed to represent a characteristic signature of a damaged element or set of elements where a signature is defined as the significant vector basis spanning the reduced residual matrix as defined by a singular value decomposition process. Stiffness damage is thereby localized by a measure of the subspace intersection dimension of the experimentally measured signature with analytically regenerated candidate elemental signatures. The analytically regenerated signatures arise from a mapping of elemental stiffness matrix sets via the transformation procedure used in the reduction process and the measured modal matrix. Multiple signatures are identified after an orthogonalization of the original target signature with respect to the most consistent signature in the previous iteration. For damage localization to be possible each mapping must project a nonnull and unique signature in the analysis set residual. This work is evaluated on damage simulations of a 155 mm aeroshell and the NASA Langley Research Center eight-bay experimental test bed.
Structural damage localization using element signature recognition
Schadensortung in Tragwerken mittels Elementsignaturerkennung
AIAA Journal (online) ; 45 , 1 ; 71-78
2007
8 Seiten, 9 Bilder, 16 Quellen
Article (Journal)
English
Anpassung (Übereinstimmung) , Fachwerkträger , Finite-Elemente-Methode , Freiheitsgrad , mathematische Transformation , mathematisches Modell , Matrix (Zahlenschema) , Matrizenrechnung , Merkmalerkennung , Modalanalyse , Schadensortung , Schwingungsanalyse , Steifigkeit , Störungstheorie , Theorie-Experiment-Vergleich , Tragwerk (Flugzeug)
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