Session: 01-10-01: Congress-Wide Symposium on NDE & SHM: Ultrasonic Waves for Material Characterization and Damage Assessment

Paper Number: 99546

99546 - Damage Identification for Beam-Like Structures Based on Proper Orthogonal Modes of Guided Wavefields 

Engineering structures in service can suffer from operational loads and long-term environmental effects, which cause unwanted structural failures and casualties. The necessities to lower the possibility of failures and extending useful lives of the structures motivate to develop accurate and noise-robust damage identification methods, which can lead to efficient early maintenance operations. Recently, guided wavefield-based methods for damage identification have been studied widely thanks to the availability of scanning laser Doppler vibrometers (SLDVs), which can measure vibrational velocities of points on a predefined grid assigned to a structure. A guided wavefield can show features of guided waves propagating along a structure and their interactions with discontinuities associated with damage. The interactions can be referred to as local anomalies, which can be intensified to identify the location and extent of the damage by advanced signal processing techniques. Recently, guided wavefield-based methods have been studied for damage identification by extracting and localizing local anomalies in guided wavefields in the time- and frequency-wavenumber domains. Meanwhile, proper orthogonal modes (POMs) obtained by the proper orthogonal decomposition has been studied for vibration-based damage identification. In this paper, the effectiveness of POMs of guided wavefields for damage identification in beam-like structures is studied. Since local anomalies in the POMs can be covered by global trends of the POMs, the continuous wavelet transform is used to suppress the global trends and intensify the local anomalies. The fundamental mechanism of how the continuous wavelet transform with Gaussian wavelet functions of a proper order can suppress the global trends of POMs and intensify local anomalies of POMs is explained. Significant POMs used for damage identification are determined by an adaptive truncation technique. The proper orders of the Gaussian wavelet functions, i.e., their number of vanishing moments, are determined based on the modal assurance criterion and a statistical criterion. The continuous wavelet transform of the significant POMs with Gaussian wavelet functions of the proper orders are used to yield an accumulative damage index. Numerical and experimental investigations of the proposed method are conducted on damaged beam-like structures. Their results verified that the proposed method is accurate and noise-robust for identifying the location and extent of damage in beam-like structures.  It was found that (1) the proposed method can accurately identify the location and extent of damage, and (2) the proposed method is robust for different scenarios of damage, excitation forces and measurement noise. In future works, it is worthwhile to conduct investigations on the location of damage at the end of beam-like structures by using POMs of guided wavefields.

Presenting Author: Yongfeng Xu University of Cincinnati

Presenting Author Biography: Yongfeng Xu is an assistant professor in the University of Cincinnati.

Authors:

Wei Zhou University of Cincinnati
Yongfeng Xu University of Cincinnati