Quantitative Detection of Delaminations in CFRP Composite Plate by Spatial-Frequency-Wavenumber Analysis Based on Laser Ultrasonic Guided Waves

To comprehensively quantitative assessment of delamination location in CFRP composite plates, a Lamb wave spatial frequency wavenumber imaging method based on laser ultrasonic full-wavefield scanning inspection is proposed in this paper. For a CFRP composite plate specimen containing a delamination, a piezoelectric sensor is arranged to excite a sinusoidal modulation tone-burst signal. A laser transducer is used for pointwise reception to obtain Lamb waves full-wavefield data. Frequency domain filtering were performed on the wavefield signal to obtain single-mode wavefield. Short-space Fourier transform and instantaneous wavenumber analysis were applied to single-mode wavefield signal to obtain a distribution image of Lamb wave spatial wavenumber respectively. At the same time, the Lamb wave dispersion relation in CFRP composite plate is analyzed, and the delamination location is calculated based on this relationship. Finally, it can be seen from the imaging results that instantaneous wavenumber analysis can accurately locate the distance between the delamination and the laser scanning detection surface, but the short-space Fourier transform technology cannot identify the location of defects under the experimental parameters set in this paper.