Scattering of obliquely incident ultrasonic waves by a cylindrically layered solid structure

The scattering theory for ultrasonic waves obliquely incident on a cylindrical threelayered solid structure is introduced.The intermediate annulus between the outer and inner medium can be simulated as an interface layer,if the layer thickness is small as compared with the wavelength and the inner radius.By asymptotically expanding the transfer matrix that relates stresses and displacements on both sides of the annulus,a three-dimensional spring model is developed to describe the mechanical properties of the interface layer.Numerical computations based on this model have been made for the relations of longitudinal wave scattering crosssections in a glass fiber/aluminum structure with the interface properties.