RESEARCH ON SIGNAL EXCITATION OPTIMIZATION IN LAMB WAVE IMAGING METHOD

The plate structure is susceptible to damages such as cracks, spalling, and fatigue caused by external load impact, chemical corrosion and other effects. Aiming at the problem that ultrasonic Lamb waves have multi-modality and frequency dispersion effects during the propagation of plate structures, and the damage information is difficult to identify. The frequency-wavenumber(f-k) domain filtering method was adopted. By studying the numerical simulation model of the isotropic material plate in the f-k domain sub-modal imaging method, the comparison of driving performance based on 400kHz sine modulated five-peak wave signal and 250-550kHz bandwidth linear Chirp signal is studied. The results show that the damage reflection energy of the two modes in the Chirp signal band is stronger than the sinusoidal modulated five-peak wave signal, and the feasibility of the proposed signal for multi-damage detection is verified by comparing the wave field and time domain signals.