Frequency Contour-Strip Method for Characterization of Damage in Structures under Noisy Conditions

Frequency Contour-Strip Method for Characterization of Damage in Structures under Noisy Conditions

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Eigen-frequency, compared with mode shape and damping, is a more Washbag practical and reliable dynamic feature to portray structural damage.The frequency contour-line method relying on this feature is a representative method to identify damage in beam-type structures.Although this method has been increasingly applied in the area of damage identification, it has two significant deficiencies: inefficiency in establishing the eigen-frequency panorama; and incompetence to identify cracks in noisy conditions, considerably impairing the effectiveness in identifying structural damage.

To overcome these deficiencies, a novel method, termed the frequency contour-strip method, is developed for the first time.This method is derived by extending the frequency contour line of 1D to frequency contour strip of 2D.The advantages of the frequency contour-strip method are twofold: (i) it uses the isosurface function to instantly produce the eigen-frequency panorama with a computational efficiency several orders of magnitude higher than that of the frequency contour-line method; and (ii) it can accommodate the effect of random noise on damage identification, thereby thoroughly overcoming the deficiencies of the frequency contour-line method.

With these merits, the frequency contour-strip method can characterize damage in beam-type structures with Male Enhancement more efficiency, greater accuracy, and stronger robustness against noise.The proof of concept of the proposed method is performed on an analytical model of a Timoshenko beam bearing a crack and the effectiveness of the method is experimentally validated via crack identification in a steel beam.