Investigation of time-reversed ultrasonic waves focusing in multilayered media

Abstract

In the paper we investigate the time-reversal approach application for non-destructive evaluation of layered structures and it is shown, that the time-reversal mirrors (TRM) can be used for detection of scattering sources in layered media and the time-reverted waves successfully pass through layer-stacking zones and refocuses to the initial source. The investigations were performed for two cases: 2-layered structure (liquid-solid) and 3-layered structure (liquid-solid-liquid). The results show that multiple reflections caused by different structure layers and boundaries were eliminated by the TRM. Wave energy does not dissipate after mode conversion at liquid-solid interfaces, but is redirected to waves which coincide in some arbitrary time instant. Numerical modeling was performed by finite element method using the commercially available software ABAQUS/Explicit.