Application of Damage Detection of Steel Structure Lamb Wave Modal Superposition Imaging Based on Scanning Laser Vibration Measurement

Abstract

Due to their high strength, high-temperature resistance, good toughness, and plasticity, steel structural plates are widely used in major engineering structures such as high-speed rail, vehicles, and civil engineering. However, they are easily damaged by external loads and impacts during long-term service. Aiming at the shortcomings of dispersion and multi-modal effects in the current Lamb wave detection, and since damage information cannot be effectively identified, this paper studies, through simulation and experiments, the Lamb wave driven by a sinusoidal modulation five-peak wave signal in a steel structure plate with flat-bottomed holes. The finite element numerical model of the propagation was established, and the corresponding damage detection experimental platform including steel and aluminum boards was built. The experimental data were obtained by Scanning Laser Doppler Vibrometer (SLDV). It can be seen from the experimental results that under the condition of the same frequency, the damage reflection energy of the two different modes is relatively obvious. Through the data fusion of the two modes, the results obtained are more accurate than the damage imaging results of the single mode in the frequency wavenumber (f-k) domain. Finally, the damage location experiment of one through hole in the steel board and the double flat bottom holes in aluminum plate are carried out to verify the feasibility of the algorithm in isotropic plate.