Detection and location of internal defects in pieces by using perpendicular ultrasonic apertures

Ultrasonic inspection with a low number of transducers located in perpendicular planes, and working in near-field conditions, constitutes a recent evaluation tool with efficient behaviour for defect detection, because this option involves a low technological cost with a good spatial resolution. Each bi-dimensional elemental area of the tested piece is insonified by different transducers, and a high resolution two-dimensional representation can be obtained by using some digital signal processing techniques specifically developed for making echo-trace combinations. Two methods for acquisition of multiple A-scan lines, and three digital signal processing combination algorithms, together with some results related to the detections of multiple defects, are presented in the paper.