TY - JOUR
T1 - Structural Damage Localization by Outlier Analysis of Signal-processed Mode Shapes
T2 - Analytical and Experimental Validation
AU - Ulriksen, Martin Dalgaard
AU - Damkilde, Lars
PY - 2016
Y1 - 2016
N2 - Contrary to global modal parameters such as eigenfrequencies, mode shapes inherently provide structural information on a local level. Therefore, this particular modal parameter and its derivatives are utilized extensively for damage identification. Typically, more or less advanced mathematical methods are employed to identify damage-induced discontinuities in the spatial mode shape signals, hereby, potentially, facilitating damage detection and/or localization. However, by being based on distinguishing damage-induced discontinuities from other signal irregularities, an intrinsic deficiency in these methods is the high sensitivity towards measurement noise. In the present paper, a damage localization method which, compared to the conventional mode shape-based methods, has greatly enhanced robustness towards measurement noise is proposed. The method is based on signal processing of a spatial mode shape by means of continuous wavelet transformation (CWT) and subsequent application of a generalized discrete Teager-Kaiser energy operator (GDTKEO) to identify damage-induced mode shape discontinuities. In order to evaluate whether the identified discontinuities are in fact damage-induced, outlier analysis is conducted by applying the Mahalanobis metric to major principal scores of the sensor-located bands of the signal-processed mode shape. The method is tested analytically on the basis of a free-vibrating beam and experimentally in the context of a residential-sized wind turbine blade subjected to an impulse load.
AB - Contrary to global modal parameters such as eigenfrequencies, mode shapes inherently provide structural information on a local level. Therefore, this particular modal parameter and its derivatives are utilized extensively for damage identification. Typically, more or less advanced mathematical methods are employed to identify damage-induced discontinuities in the spatial mode shape signals, hereby, potentially, facilitating damage detection and/or localization. However, by being based on distinguishing damage-induced discontinuities from other signal irregularities, an intrinsic deficiency in these methods is the high sensitivity towards measurement noise. In the present paper, a damage localization method which, compared to the conventional mode shape-based methods, has greatly enhanced robustness towards measurement noise is proposed. The method is based on signal processing of a spatial mode shape by means of continuous wavelet transformation (CWT) and subsequent application of a generalized discrete Teager-Kaiser energy operator (GDTKEO) to identify damage-induced mode shape discontinuities. In order to evaluate whether the identified discontinuities are in fact damage-induced, outlier analysis is conducted by applying the Mahalanobis metric to major principal scores of the sensor-located bands of the signal-processed mode shape. The method is tested analytically on the basis of a free-vibrating beam and experimentally in the context of a residential-sized wind turbine blade subjected to an impulse load.
KW - Structural Health Monitoring
KW - Damage localization
KW - Wavelet transformation
KW - Generalized discrete Teager-Kaiser energy operator
KW - Outlier analysis
KW - Structural Health Monitoring
KW - Damage localization
KW - Wavelet transformation
KW - Generalized discrete Teager-Kaiser energy operator
KW - Outlier analysis
U2 - 10.1016/j.ymssp.2015.07.021
DO - 10.1016/j.ymssp.2015.07.021
M3 - Journal article
SN - 0888-3270
VL - 68-69
SP - 1
EP - 14
JO - Mechanical Systems and Signal Processing
JF - Mechanical Systems and Signal Processing
IS - February
ER -