Fast guided waves inspection using compressive sensing and wavenumber domain analysis

Many nondestructive evaluations and structural health monitoring techniques for plate like structures rely on the full field analysis related to stress guided waves propagation. Such techniques can be quite slow as in general the acquisition of the full wave field and its processing, aimed at extracting damage related information, are time consuming processes. Therefore, strategies to reduce the acquisition time and improve the damage detection and quantification are sought. This research describes a method based on Compressive Sensing (CS) and a wavenumber estimation technique that can lead to fast scanning and improved damage detection. The proposed technique exploits the full wavefields which are rapidly reconstructed by applying the CS technique. Then, frequency wavenumber processing is performed to identify the maximum wavelength. Finally a dedicated masking procedure is implemented to enhance the defect-induced scattering. To demonstrate the effectiveness of the proposed techniques, several experiments were performed on aluminum structure, emulating defect with a mass. In the experiments, guided waves are excited with a piezoelectric transducer bonded to the inspected structure and sensed by an air-coupled probe mounted on a CNC machine. The results demonstrate that the proposed technique allows to reduce the amount of measurements needed and therefore the needed scanning time, as just the 20% of the Nyquist scanpoints were measured, and improves the performance of damage imaging tasks by removing automatically noise artifacts.