Compressive sensing of phased array ultrasonic signal in defect detection: Simulation study and experimental verification

Abstract

Ultrasonic phased array techniques are widely used for defect detection in structural health monitoring field. The increase in the element number, however, leads to larger amounts of data acquired and processed. Recently developed compressive sensing states that sparse signals may be accurately recovered from far fewer measurements, suggesting the possibility of breaking through the sampling limit of the Nyquist theorem. In light of this significant advantage, the novel use of the compressive sensing methodology for ultrasonic phased array in defect detection is proposed in this work. Based on CIVA software, we first present a simulated study on the effectiveness of the compressive sensing applied in ultrasonic phased array in defect detection through the average mean percent residual difference at varying compression rates. The results particularly show that the compressive sensing yields a breakthrough of the sampling limitation. We then experimentally demonstrate comparative analyses on the signals extracted from three types of artificial flaws (through-hole, flat-bottom hole, and electrical discharge machining notches) on two different specimens (made of aluminum and 20# steel). To find the optimal algorithm combination, the best sparse representation basis is chosen among fast Fourier transform, discrete cosine transform, and 34 wavelet kernels; the reconstruction performance is compared between five greedy algorithms; and the recovery accuracy is further improved via four sensing matrices selection. We also evaluate the influence of the sampling rate, and our results are comparable with the gold standard of signal compression, namely, the discrete wavelet transform.

Nondestructive Ultrasonic Inspection of Composite Materials: A Comparative Advantage of Phased Array Ultrasonic

“…Guided wave modes were generated on Al and CFRP plates by means of a commercially available phased array probe and wedges. The procedure of plate wave generation and parametric evaluation are described in detail in [8,18]. A 1.5 MHz phased array ultrasonic probe with 16 elements and related 60 degrees longitudinal wave wedge was used for guided wave generation and flaw detection.…”

“…Phased array ultrasonic testing (PAUT) can overcome conventional ultrasonic method limitations by providing the capability of signal focusing and steering at desired angles and locations [17][18][19]. In PAUT, a series of ultrasonic elements in a phased array transducer can provide the option to activate each individual element in a programmed sequence [20,21].…”

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].…”

Fully Non-Contact Hybrid NDT Inspection for 3D Defect Reconstruction Using an Improved SAFT Algorithm

“…Depending on the typical application and availability of transducers; either of these two modes is favoured. However, the use of ultrasonic transducers both as exciters as well as receivers of ultrasound has always faced some limitations, including the difficulty to use them in remote applications where it is hard or even impossible to 2 of 14 place the transducer in contact with the object under inspection [6]. The limited resolution and weak generated power of non-contact transducers used as exciters lead to a reduction of the ultrasound waves' penetration depth, limiting their application mostly to the detection of near-surface defects.…”