Techno Press
Techno Press

Smart Structures and Systems   Volume 13, Number 6, June 2014, pages 975-991
DOI: http://dx.doi.org/10.12989/sss.2014.13.6.975
 
Crack location in beams by data fusion of fractal dimension features of laser-measured operating deflection shapes
R.B. Bai, X.G. Song, M. Radzieński, M.S. Cao, W.Ostachowicz and S.S. Wang

 
Abstract     [Full Text]
    The objective of this study is to develop a reliable method for locating cracks in a beam using data fusion of fractal dimension features of operating deflection shapes. The Katz\'s fractal dimension curve of an operating deflection shape is used as a basic feature of damage. Like most available damage features, the Katz\'s fractal dimension curve has a notable limitation in characterizing damage: it is unresponsive to damage near the nodes of structural deformation responses, e.g., operating deflection shapes. To address this limitation, data fusion of Katz\' s fractal dimension curves of various operating deflection shapes is used to create a sophisticated fractal damage feature, the \'overall Katz;s fractal dimension curve\'. This overall Katz\'s fractal dimension curve has the distinctive capability of overcoming the nodal effect of operating deflection shapes so that it maximizes responsiveness to damage and reliability of damage localization. The method is applied to the detection of damage in numerical and experimental cases of cantilever beams with single/multiple cracks, with high-resolution operating deflection shapes acquired by a scanning laser vibrometer. Results show that the overall Katz\'s fractal dimension curve can locate single/multiple cracks in beams with significantly improved accuracy and reliability in comparison to the existing method. Data fusion of fractal dimension features of operating deflection shapes provides a viable strategy for identifying damage in beam-type structures, with robustness against node effects.
 
Key Words
    damage detection; crack location; multiple cracks; operating deflection shape; data fusion; fractal dimension; laser measurement
 
Address
R.B. Bai, M.S. Cao and S.S. Wang:Department of Engineering Mechanics, Hohai University, Nanjing 210098, China
R.B. Bai: Department of Engineering Mechanics, Shandong Agricultural University, Taian, 271018, China
X.G. Song:School of Electrical and Electronic Engineering, Newcastle University, Newcastle upon Tyne NE1 7RU, United Kingdom
M. Radzieński:Institute of Fluid-Flow Machinery, Polish Academy of Sciences, 14 Fiszera St., 80-231 Gdansk, Poland
W.Ostachowicz:Institute of Fluid-Flow Machinery, Polish Academy of Sciences, 14 Fiszera St., 80-231 Gdansk, Poland;
Faculty of Automotive and Construction Machinery, Warsaw University of Technology, 84 Narbutta St., 02-524 Warsaw, Poland
 

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