Guided Wave Tomography Based on Full Waveform Inversion

Abstract

In this paper, a guided wave tomography method based on Full Waveform Inversion (FWI) is developed for accurate and high resolu- tion reconstruction of the remaining wall thickness in isotropic plates. The forward model is computed in the frequency domain by solving a full-wave equation in a two-dimensional acoustic model, accounting for higher order eects such as diractions and multiple scattering. Both numerical simulations and experiments were carried out to obtain the signals of a dispersive guided mode propagating through defects. The inversion was based on local optimization of a waveform mist func- tion between modeled and measured data, and was applied iteratively to discrete frequency components from low to high frequencies. The resulting wave velocity maps were then converted to thickness maps by the dispersion characteristics of selected guided modes. The results suggest that the FWI method is capable to reconstruct the thickness map of a irregularly shaped defect accurately on a 10 mm thick plate with the thickness error within 0.5 mm.

Seismic wavefield imaging of Earth’s interior across scales

“…FWI is computationally and algorithmically demanding, and, although these demands hampered progress for many decades, these restrictions have been largely overcome in the past decade, due to advances in algorithms and computing technology. Today, FWI is widely used in applications including medical imaging [10][11][12][13][14] , nondestructive testing [15][16][17][18][19][20][21][22][23][24] , near-surface characterization [25][26][27][28][29][30] , onshore and offshore exploration seismology [31][32][33][34][35][36][37][38][39] , deep crustal seismic imaging [40][41][42][43][44][45][46][47] , earthquake seismology [48][49][50][51][52][53][54] and ambient-noise seismology 55,56 . A comprehensive ove...…”

“…Applications of seismic FWI can be categorized as controlled-source, earthquake and ambient-noise seismology. In addition to hydrocarbon exploration and deep crustal imaging [40][41][42][43][44][45][46][47] , controlled-source applications can be further subdivided by scale into medical imaging [10][11][12][13][14] , nondestructive testing [15][16][17][18][19][20][21][22][23][24] and near-surface charac terization of the top tens of metres of the Earth [25][26][27][28][29][30] , but these are beyond the scope of this Technical Review. Since 2010, ambient-noise FWI based on seismic interferometry [159][160][161] has emerged 55,56 .…”

A Sparse Model of Guided Wave Tomography for Corrosion Mapping in Structure Health Monitoring Applications

“…However, its performance relies on the background estimate being sufficiently accurate via ray tomography. Besides on these three tomography algorithms, the full wave-form inversion (FWI) method presents a novel nonlinear inverse scattering model to implement reconstruction images of guided wave tomography [23]. Compared with diffraction tomography, FWI allows higher order diffraction and scattering and has the same theoretical resolution limit [24].…”

Inversion method to reconstruct fault transient traveling wave on overhead transmission lines

“…The waveform inversion technique is derived from geological exploration . In exploration seismograph system, an artificial source launches seismic waves to the ground.…”