Transmitter beamforming and weighted image fusion–based multiple signal classification algorithm for corrosion monitoring

Abstract

With the increase in aging aircrafts, corrosion monitoring has attracted much attention in the structural health monitoring area. Multiple signal classification has been gradually applied to structural health monitoring area as a new promising method because of its ability of directional scanning and the potential to monitor multiple signal sources. However, applying multiple signal classification algorithm to monitor real damage still faces some challenges. First, the scattered Lamb waves obtained using a single actuator is relatively weak, making the signal-to-noise ratio of the scattered signals low and resulting in the low precision of multiple signal classification–based monitoring. Second, linear sensor array–based structural health monitoring methods have the problem of blind area at the angles close to 0° and 180°. To meet these challenges and target at providing monitoring ability of both the position and severity of the damage, a novel transmitter beamforming and weighted image fusion–based multiple signal classification algorithm is proposed using a dual array that consists of two linear sensor arrays to enhance the amplitude of scattered Lamb waves from corrosion, improve its signal-to-noise ratio and eliminate the blind area. The corrosion severity can be evaluated by analyzing the largest eigenvalue of signal covariance matrix developed using the multiple signal classification algorithm. The proposed transmitter beamforming and weighted image fusion–based multiple signal classification algorithm is verified on aluminum plates with real corrosion damages at five stages. Experimental results show that the proposed method can realize corrosion monitoring with a good precision even at the blind monitoring area.

Sector Piezoelectric Sensor Array Transmitter Beamforming MUSIC Algorithm Based Structure Damage Imaging Method

“…Qing et al [40] proposed a damage monitoring method for torsional elastic waves, which realized the monitoring of high attenuation honeycomb structures. Bao et al [41,42] proposed the transmitter beamforming MUSIC algorithm based on a bilinear array and achieved low SNRs corrosion damage monitoring in a reinforced aviation structure. The array error was also corrected, and thus, the localization accuracy of the algorithm was improved.…”

Frequency Aliasing-Based Spatial-Wavenumber Filter for Online Damage Monitoring

“…In the existing SHM technologies, the damage imaging method which has high signal-to-noise ratio can visually indicate damage location and size. Examples of these imaging techniques include the delay-and-sum method [6][7][8][9], time reversal method [10][11][12][13], probabilistic diagnostic algorithm [14][15][16][17], phased array method [18][19][20][21], multisignal classification method [22][23][24][25][26], and spatial-wavenumber filter method [27][28][29][30][31][32][33][34][35]. Among them, the spatial-wavenumber filter method, which has been extensively studied, can extract the specific mode of the Lamb wave, distinguish the incident wave and damage scattering wave, and reduce the overlap of Lamb wave signals [33][34][35].…”

Identification and Compensation Technique of Non-Uniform Temperature Field for Lamb Wave-and Multiple Sensors-Based Damage Detection

“…Lamb wave-based structural health monitoring (SHM) technique has been proved to be one of the strongest techniques for online and real-time damage detection of aircraft structures because of the superior capability of travelling long distances and covering large monitoring area with limited numbers of piezoelectric sensors [1]. Plenty of Lamb wave-based damage detection algorithms, including delay and sum [2,3], phased array [4,5], tomography [6,7,8,9,10,11], and migration [12,13], have been developed. Comprehensive reviews on the application of Lamb wave for structural health monitoring can be found in the literature [1,14,15].…”

“…Comprehensive reviews on the application of Lamb wave for structural health monitoring can be found in the literature [1,14,15]. Depending on whether reference data of Lamb wave in the pristine structure is needed or not, these algorithms can be divided into two categories, i.e., reference-free algorithms [16,17,18,19] and reference-dependent ones [2,3,4,5,6,7,8,9,10,11,12,13]. Reference-dependent algorithms are more practical than reference-free ones for real application in aircraft structures due to the complex nature of the Lamb wave, including multiple mode, modes conversion and scattering at the boundary.…”