INTEGRAL APPROXIMATION METHOD FOR CALCULATING ULTRASONIC BEAM-PROPAGATION IN ANISOTROPIC MATERIALS

Plane-wave solutions to the acoustic wave equations in a generally ani sotropic solid are reviewed, along with their connection to geometric ray theory. A Fourier-transform formulation of the field of a focused beam (coherent point source) passed from a liquid couplant to an aniso tropic specimen through a plane surface is derived. The integral is ap proximated asymptotically using the stationary-phase method. The resul t for isotropic media is derived analytically to facilitate a direct c omparison to the ray theory. The application of this method to the ani sotropic case is illustrated, using the real world example of the aust enitic stainless-steel weld.