Array Based Defect Detection and 2d Reconstruction: a Self Contained, Non-iterative Technique

Amongst a number of NDE methods Ultrasonics has been a tool of choice to inspect, since the likely defects and important material properties are most easily, and inexpensively, uncovered in ultrasonic NDE. Due to physical constraints of accessing the other side of the structure and the immeasurability of transmitted signal (like cardiovascular imaging), ultrasonic reflection technique has great importance in NDE and medical. In present work, ultrasonic reflection methodology has been devised for reconstruction of centered as well as offset defects with equal efficiency. It involves defect characterization by analyzing the reflected signal data collected using phased array ultrasound instrument in pulse echo mode. Approximate location of the underlying defect was estimated by performing a linear scan across the accessible periphery of the specimen. Accordingly sectorial scan data collected at various positions of the probe along the boundary of the specimen was assimilated into a single database. This was succeeded by an extensive error analysis of the data which aimed at filtering out the various noise components. The filtered output was acted upon by the MATLAB code to reconstruct the defect. From the point of view of computation time and quality of reconstructed image, the algorithm has reconstructed defects with reasonable accuracy. The samples included various defect geometries; circular, elliptical, rectangular, to name a few. Various material combinations of samples and their respective defect inserts were tested, like, aluminium-steel, perspex-air, steel-epoxy, etc. Results have shown that algorithm is capable of characterizing multiple defects with a little lesser accuracy depending on defect dimensions. Comparisons with actual defect geometries have been presented.