Acoustic emission localization in plates with dispersion and reverberations using sparse PZT sensors in passive mode

Abstract

A strategy for the localization of acoustic emissions (AE) in plates with dispersion and reverberation is proposed. The procedure exploits signals received in passive mode by sparse conventional piezoelectric transducers and a three-step processing framework. The first step consists in a signal dispersion compensation procedure, which is achieved by means of the warped frequency transform. The second step concerns the estimation of the differences in arrival time (TDOA) of the acoustic emission at the sensors. Complexities related to reflections and plate resonances are overcome via a wavelet decomposition of cross-correlating signals where the mother function is designed by a synthetic warped cross-signal. The magnitude of the wavelet coefficients in the warped distance–frequency domain, in fact, precisely reveals the TDOA of an acoustic emission at two sensors. Finally, in the last step the TDOA data are exploited to locate the acoustic emission source through hyperbolic positioning. The proposed procedure is tested with a passive network of three/four piezo-sensors located symmetrically and asymmetrically with respect to the plate edges. The experimentally estimated AE locations are close to those theoretically predicted by the Cramèr–Rao lower bound.

Toward the Upscaling of Guided Waves-Based NDE and SHM in Aeronautics

“…The methodologies to locate impact based on guided waves can be mainly classified in three groups: (i) inverse methods that locate the impact via model updating, by using neural networks, genetic algorithms, or time reversal [3][4][5][6]; (ii) hyperbolic positioning algorithms that locate impact by using the difference in time-of-flight (ToF), i.e., time difference of arrival (TDoA), of the wavefronts captured by different sensors and proper triangulation algorithms [7][8][9][10][11][12][13]; and (iii) direct strategies which allow to locate the wave source by capturing the wave direction of arrival (WDA) without recurring to the waves ToF [14][15][16][17].…”

Acoustic Emission Source Localization System Using Fiber Bragg Grating Sensors and a Barycentric Coordinate-Based Algorithm

“…AE technique is used to detect, locate, and assess defects. To obtain AE wave, some AE sensors have been widely used, such as piezoelectric sensors (PZT) and capacitive AE sensors [5][6][7][8]. However, the traditional AE sensors have the disadvantages such as complex structure, weak antielectromagnetic interference, and unsuitability for distributed measurement.…”

Impact Localization Method for Composite Plate Based on Low Sampling Rate Embedded Fiber Bragg Grating Sensors

“…In the passive method, these three features, TDOA (Time Difference Of Arrival), AOA (Angle Of Arrival), and RSSI (Received Signal Strength Indication), of the signal are most widely used. For the TDOA-based method, it is easy to implement and does not need specific sensor layout or extra computing power [11,[13][14][15]. However, it requires low signal noise ratio (SNR) of the signal and high sampling rate to obtain the accurate time difference.…”