Research on Internal Damage Imaging Based on Laser Ultrasonic Wavenumber Domain Filtering

This paper proposes a wavenumber domain filtering method for completely non-contact laser ultrasonics. which is applicable to the detection of damage on the inside of the isotropic and anisotropic structures. Firstly, the A0 modal part of the Lamb signal is extracted. Secondly, a three-dimensional Fourier transform is applied to the signal, which transforms the signal from the space-time domain to the wavenumber-frequency domain. Finally, the data are filtered by the wave-number domain filtering method and the Fourier inverse transform is performed to obtain a resultant map that can characterize the defect location. This method achieves accurate imaging of damage on aluminum plate and CFRP plate.