INTERPRETATION OF ELASTIC-WAVE SCATTERING THEORY FOR ANALYSIS AND DESIGN OF FLAW-CHARACTERIZATION EXPERIMENTS - LONG-WAVELENGTH LIMIT

Recently, the results of a general theory of the scattering of elastic waves from a flaw embedded in an isotropic medium were shown in the far-field limit to be compactly represented by a single vector, the f vector. Studying the f vector is thus a way to investigate systematically the dependence of the scattering on the polarization of the incident mode, scattering angle, changes in material parameters, and shape. In the long-wavelength limit the f vector is exactly determinable and exhibits significant features of the flaw. We discuss long-wavelength scattering results for volume flaws and idealized cracks and compare some of the results with those of the Born approximation, which has already been calibrated by comparison to exact calculations and experiment.