Damage identification via Laplacian filtering of full wavefield acquisitions

Lamb wavefield imaging in Non-Destructive Testing (NDT) is usually exploited for characterizing the propagation evolution of Guided Waves (GWs) and their interaction with damages in plate-like structures. In typical set-ups, a fixed source is used to generate the GWs, while laser-based receivers are used to acquire the displacement of multiple plate points over a pre-defined spatial grid at different time instants. The interaction between Lamb waves and the damage can be enhanced by specific techniques to reveal the damage position such as cumulative kinetic energy methods, reflection separation and Laplacian filtering in time domain. In this work, we propose an innovative signal processing method to highlight the damage influence in a CFRP by Scanning Laser Doppler Vibrometer (SLDV) measurements based on Laplacian filter in the wavenumber domain. The Laplacian filter in the k-space over multiple frequencies outperforms the same filtering technique in the time domain, enhancing the damage contribution.