Multi-damage identification based on joint approximate diagonalisation and robust distance measure

12th International Conference on Damage Assessment of Structures

Cao, S.^1 ; Ouyang, H.^1,2

Centre for Engineering Dynamics, School of Engineering, University of Liverpool, Liverpool

L69 3GH, United Kingdom^1

State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, Dalian

116023, China^2

关键词: Ambient excitation;    Coefficient of variation;    Damage Identification;    Frequency domain decomposition;    Joint approximate diagonalisation;    Operational deflection shapes;    Participation factors;    Practical engineering;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/842/1/012022/pdf
DOI  :  10.1088/1742-6596/842/1/012022

来源: IOP

【 摘 要 】

Mode shapes or operational deflection shapes are highly sensitive to damage and can be used for multi-damage identification. Nevertheless, one drawback of this kind of methods is that the extracted spatial shape features tend to be compromised by noise, which degrades their damage identification accuracy, especially for incipient damage. To overcome this, joint approximate diagonalisation (JAD) also known as simultaneous diagonalisation is investigated to estimate mode shapes (MS's) statistically. The major advantage of JAD method is that it efficiently provides the common Eigen-structure of a set of power spectral density matrices. In this paper, a new criterion in terms of coefficient of variation (CV) is utilised to numerically demonstrate the better noise robustness and accuracy of JAD method over traditional frequency domain decomposition method (FDD). Another original contribution is that a new robust damage index (DI) is proposed, which is comprised of local MS distortions of several modes weighted by their associated vibration participation factors. The advantage of doing this is to include fair contributions from changes of all modes concerned. Moreover, the proposed DI provides a measure of damage-induced changes in 'modal vibration energy' in terms of the selected mode shapes. Finally, an experimental study is presented to verify the efficiency and noise robustness of JAD method and the proposed DI. The results show that the proposed DI is effective and robust under random vibration situations, which indicates that it has the potential to be applied to practical engineering structures with ambient excitations.