The far-field scattering response of a side drilled hole in single/layered anisotropic media in ultrasonic pulse-echo setup

Ultrasonic testing for defects in anisotropic material is one of the difficult problems in non-destructive testing (NDT) with elastic waves. Even though a series of studies have been performed on the waves interacting with flaws, however, only a small portion was on anisotropic materials. In this paper, an analytical solution for the far-field scattering response of a side drilled hole (SDH) in anisotropic media in an ultrasonic pulse-echo setup with its incident wave normal to the axis of cylindrical hole is presented. The solution is based on the Kirchhoff approximation, and validated upon several numerical examples, yielding satisfactory results in the comparison to the results achieved by different methods. Also, an attempt is made to extend the use of this solution from homogeneous anisotropic media to weld, which is considered as the multi-layer anisotropic media.