文档介绍：
Automatic Defect Detection in Ultrasonic TOFD D-Scan
Data Using Digital Image Processing Method#
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CHI Dazhao, GANG Tie*
(State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin
150001)
Abstract: In ultrasonic time of flight diffraction (TOFD) D-scan image, only a small fraction
represents defects, whereas the majority of the data is considered redundant. Because of the low
contrast between defect and background image, TOFD suffers from the difficulty of large amounts of
time and effort consuming in manually interpretation of D-scan image. In addition to this, due to the
nature of the weak diffracted signals, the human factor introduces inconsistency into the interpretation.
In order to distinguish weld defects from the D-scan data automatically and reliably, a defect detection
method based on image processing technique is proposed in the paper. Firstly, image pre-processing
including clutter and noise suppression is conducted. Secondly, information entropy based image
segmentation technique is employed to extract defect in the pre-processed image. At last, mathematical
morphological based post-processing is carried out. The experiment shows that with the proposed
method, TOFD can be used as an automatic weld defect detection technique.
Key words: welding process and equipment; ultrasonic