Surface wave conversion analysis on a lengthwise soldered circular cylindrical shell

This paper deals with wave conversion phenomena through a study of the acoustic scattering from a stiffened cylindrical shell at normal incidence. The analysis presented follows the experimental study which explored the acoustic wave propagation and scattering processes in the case of air-filled submerged cylindrical shells having internal axial solder [J. Chiumia, N. Touraine, D. Décultot, G. Maze, A. Klauson, and J. Metsaveer, J. Acoust. Soc. Am. 105, 183–193 (1999)]. The significant observed phenomena were generation, reflection, and conversion of circumnavigating waves at the solder. The present work confirms the presence of the three phenomena through a theoretical approach based on the elasticity theory. In particular, resonances with new feature whose frequencies are very close to those of the $S0$ wave are highlighted here. The origin of this new resonance feature is identified and can be associated to wave type conversions between $A0$ and $S0$ Lamb waves, occurring when these propagating waves encounter the solder. The air-filled stainless steel studied tube submerged in water has an internal lengthwise solder, which is, in theoretical computations, considered as an internal axial mass layer. The reduced frequency range $(k1a)$ of the study is between 25 and 90, (⁠$k1$⁠: wave number in water; $a$⁠: external radius of the shell).