Shape reconstruction of mixed type void flaws using Born inversion method

We study an approximate technique for determining the shapes of mixed type void flaws in elastic media from knowledge of the ultrasonic scattering amplitudes. It is well known that the technique is highly effective under weak scattering conditions. In the paper, two cement paste cylindrical specimens with mixed type void flaws are prepared and ultrasonic measurements are carried out by experimental means. The measurement area is restricted in the plane perpendicular to the axis of cylindrical specimen. The measured wave data are fed into the approximate technique formula-the Born inversion method and cross-sectional image is obtained. We find that good results have been obtained for strong scattering void flaws such as mixed type void flaws in cement paste cylindrical specimens.