ULTRASONIC IMAGE DATA-PROCESSING FOR THE DETECTION OF DEFECTS

Ultrasonic testing is widely used in material inspection. Forming an u ltrasonic image helps the operator in decision making. This image, how ever, can result in common interpretation difficulties during the test ing of heterogeneous or noisy zones. A new method of detection of defe cts located in a noisy medium is presented: it is based on considering the ultrasonic grey-level image from the beginning of the analysis. T he data processing used here is searching for a certain determinism in the spatial and temporal evolution of the image in the presence of a defect: a first criterion studies the horizontal stability of the grad ients in the image and a second considers the transient temporal natur e of the defect echo. Results obtained on artificial defects located i n real welds are shown. Conclusions with respect to the quality of thi s defect detection method are drawn.