A0 Wave in a Submerged Stiffened Cylindrical Shell

Abstract

Abstract The backscattering of a normal incident plane acoustic wave by a stiffened cylindrical shell is considered. The studied cylindrical shell is made of stainless steel and its internal to external radius ratio is b/a = 0.98. The shell submerged in water is strengthened by an internal plate of the same material and thickness, which is diametrically soldered. As for the unstiffened shell, A wave (Scholte-Stoneley wave) and S0 wave (first symmetrical Lamb wave) are detected in the frequency range investigated (50–200 ka where k is the wave number in water). On the contrary, the presence of the plate into the tube allows the detection of A0 wave (flexural Lamb wave) whereas it is not observed for the unstiffened shell, owing to the attenuation of the wave during the propagation around the tube. In particularl, A0 wave could be reflected on the junction with enough energy to re-emit in water. Furthermore, wave type conversions are allowed by way of the junctions: S0–A0 wave conversions are observed.