Sodagar S., Honarvar F., Sinclair A.

An analytical model is developed for the scattering of acoustic waves from an immersed transversely isotropic rod covered by a cylindrical isotropic cladding. The mathematical formulation is derived for the far-field backscattered amplitude spectrum and displacement field resulting from oblique insonification of the clad rod. The validity of the mathematical model is verified by comparing the results with data available in the literature for simpler cases such as isotropic rods and isotropic clad rods. It has been observed that when interacting with mechanical waves, transversely isotropic materials show two different behaviors and consequently they can be classified as type I and type II. In the current paper, using the developed mathematical model, the form functions and phase diagrams for these two types of transversely isotropic cylinder are studied. It is shown that in the phase diagram of the far-field backscattered amplitude spectrum at small angles below the critical angles a phase-shift of 180 degree is observed for some resonance frequencies while the phase-shift in other resonance frequencies is less than 180 degree. But beyond the second critical angle none of the resonance frequencies experience a phase-shift of 180 degree.