<p>The quantitative measurements of the corrosion in pipeline, pressure vessels and plate-like waveguide structures are one of the leading challenges in Nondestructive Testing (NDT). Ultrasonic imaging techniques provide a new and easy way to perform quantitative measurement of the degree of corrosion in various probed structures. Compared with other imaging techniques, full waveform inversion (FWI) is one of the most advanced defect reconstruction algorithms with the imaging resolution attaining the magnitude of one wavelength of the probing acoustic signal. In this article, we investigate the full potential of FWI approach by using it to reconstruct the shape and thickness distribution of plate-like structure with multi-complex defects. The results show that, the FWI approach significantly surpasses other fast screening methods like the defect probability reconstruction algorithm (DPRA) in terms of the shape and remaining thickness of the defects, as the DPRA can only give defect weight distribution instead of thickness distribution on the probed structure. What's more, in the DPRA, defect weight distribution is reconstructed based on elliptical distribution function, such linear reconstruction algorithm cannot include the effect of higher order terms of the reflected signal, which means it is not possible for such methods to attain better resolution than the FWI approach. Consequently, if we need to perform quantitative analysis of the corrosion, the FWI method is one of the most promising algorithms to be applied in the comprehensive inspection of the complex structures in the industrial field.</p>

High Resolution Multi-Complex Defect Imaging Using Full Waveform Inversion Technique

Paper Proceedings: https://asmedigitalcollection.asme.org/qnde/QNDE2021/volume/85529

ASME 2021 48th Annual Review of Progress in Quantitative Nondestructive Evaluation (QNDE2021)

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