David A. Hutchins
Dept. of Eng., Univ. of Warwick, Coventry CV4 7AL, UK
Ultrasonic tomography may be used as a method for imaging the internal structure of a wide range of solid materials. To do so requires tomographic reconstruction programs that can deal with irregular geometries, acoustic raybending and the possible presence of velocity anisotropy. Image reconstruction techniques are now available to deal with such problems, and have been applied to several situations of interest to materials characterization. The first of these involves the study of samples in bulk solid form, where a scanning system involving sliding contact transducers has been used to collect ultrasonic data and image materials that have been subject to thermal cracking. Additional studies have investigated the failure of fiber-reinforced polymer composites under applied load. In both cases, correlation with acoustic emission (AE) data has been performed. Other work has used immersion and noncontact ultrasonic transduction to image the structure of thin plate material using Lamb waves. In all cases, images will be presented and conclusions drawn on the type of information available from such images. [Work supported by SERC.]