Effect of porous surface layer on wave propagation in elastic cylinder immersed in fluid

Abstract

To study the damage of an elastic cylinder immersed in fluid, a model of an elastic cylinder wrapped with a porous medium immersed in fluid is designed. This structure can both identify the properties of guided waves in a more practical model and address the relationship between the cylinder damage degree and the surface and surrounding medium. The principal motivation is to perform a detailed quantitative analysis of the longitudinal and flexural modes in an elastic cylinder wrapped with a porous medium immersed in fluid. The frequency equations for the propagation of waves are derived, each for a pervious and an impervious surface employing Biot theory. The influences of the various parameters of the porous medium wrapping layer on the phase velocity and attenuation are discussed. The results show that the influence of porosity on the dispersion curves of guided waves is much more significant than that of thickness, whereas the phase velocity is independent of the static permeability. There is an apparent “mode switching” between the two low-order modes. The characteristics of attenuation are in good agreement with the dispersion curves results. This work can support future studies for optimizing the theory of cylinder or pipeline damage detection.