Estimation of wall reduction of plate using the fundamental symmetric mode lamb wave

Final aim of this study is to estimate the corrosion-induced wall reduction of the bottom plate in storage tanks from the outside of the tank. We excited strong S-0-mode Lamb waves by impacting the center of the edge plane of a plate, and monitored both the amplitude and arrival time of the S-0-mode reflected from artificial slits by a low frequency receiver mounted at the edge plane. The amplitude of reflected S-0-mode Lamb waves increased proportionally with slit depth. Locations of defects, calculated from the arrival time of reflected S-0-mode Lamb waves, were estimated as the locations of actual slits with an error below 2%.