3. Defect Characterization by Quantitative Ultrasonics
The development of several approximations appears to permit accurate and practical calculations of the scattering of elastic waves from volumetric and crack-like defects of simple shapes if the wavelength of the incident wave is larger than the characteristic length of the shape. These approximations, which I call the quasi-static and extended quasi-static, use static solutions of defects in uniform strains to predict scattered (dynamic) fields. Since static solutions for several simple defect shapes (oblate and prolate spheroid, ellipsoid, and circular and elliptical cracks) are available, scattering predictions are possible, and the results of such calculations are presented.
Gubernatis, J. E., "Long Wave Scattering of Elastic Waves from Volumetric and Crack-Like Defects of Simple Shapes" (1978). Proceedings of the ARPA/AFML Review of Progress in Quantitative NDE, September 1976–June 1977. 8.