Analysis of Ultrasonic Wave Scattering for Characterization of Defects in Solids

Résumé du livre

Measurements and analysis have been carried out on the scattering of ultrasonic elastic waves by voids and solid inclusions in titanium alloy. Both direct scattered amplitudes and mode converted scattering amplitudes were measured for incident shear and incident compressional plane waves. The scatterers were spherical and ellipsoidal in shape. Exact calculation for spherical shapes of arbitrary radius and elastic properties were obtained and compared with the experimental measurements. For other shapes, exact calculations are either impossible or impractical. Scattering from an arbitrary shape was expressed in terms of an integral equation from which an improved Born approximation reduces to the Rayleigh limit for scattering by spheres at low frequencies and to the known static stress field in ellipsoids for zero frequencies. The use of a variational approach has been explored which appears to have the capability of significantly extending the range of validity of the usual long wavelength limit approximations. (Author).