Improved spatial filter based damage imaging method on composite structures

To overcome the problem of frequency dispersion, multi-mode and mode convention of Lamb wave signal propagation on composite structures, a spatial filter based strunctural damage imaging method improved by Hilbert transform was proposed. The principle of signal synthesis and imaging based on spatial filter was analyzed. Based on the principle, Hilbert transform was adopted to construct analytic signals of time domain response signals of sensors to participate in the process of signals synthesis and imaging. Imaging of simulating acoustic source was done to validate the feasibility of this method, and then imaging of excitation source and damage on plate-like structures of carbon fiber composite materials was performed to validate the function of this method. The research shows that this method can recognize the angle of damage and the time-of-arrival of damage scattering signals relative to the piezoelectric transducers array efficiently.