STRUCTURAL DAMAGE DETECTION AND IMAGE BASED ON THE ZERO MIGRATION RECORD OF THE SYNTHETICAL PSEUDO-SPECTRUM

The structural damage detection and migration image based on the zero migration-record of synthetical pseudo-spectrum are discussed. The different forms of numerical calculation formula are deduced from the scalar wave equation of two dimensions. The problem of boundary absorbility is handled by the counter-cyclical extension, which eliminates the illusion of boundary reflection and the disturbance wave. The zero migration record which synthesized by the wave field extrapolation can adapt the complex damage form and the medium in which transverse velocity changes obviously. The dynamic characters of pseudo-spectrum, such as bizarrerie, frequency dispersion, wave shape, amplitude, displacement, energy and concentration coefficient of dynamic stress, are analyzed according to the wave equation. The snapshot and time section of the wave field are obtained which realize the visual detection and recognition of the structural damage. The numerical example shows a good feasibility of the pseudo-spectrum migration to engineering structures detection.