DIFFRACTION OF ULTRASONIC-WAVES BY PENNY-SHAPED CRACKS IN METALS - THEORY AND EXPERIMENT

In this paper an analytical solution to the diffraction of elastic waves by penny-shaped cracks in metals is compared with experimental observations. The analysis, which is based on elastodynamic ray theory, is valid for the region of ka > 1. A digitized spectrum analysis system is described which measures the frequency components of the waves diffracted from a 2500-μ-radius crack in diffusion bonded titanium. The amplitude spectra show good agreement between experiment and theory. The theoretically predicted periodicity of the diffracted spectra provides a simple formula for the inverse problem. Application of this formula to the experimental measurements determines the crack size with excellent accuracy. © 1979 Acoustical Society of America