Automated inspection system for detecting metal surface cracks from fluorescent penetrant images

Yonghong Tang; Aiqun Niu; William G. Wee; Chia Yung Han

doi:10.1117/12.205514

27 March 1995 Automated inspection system for detecting metal surface cracks from fluorescent penetrant images

Yonghong Tang, Aiqun Niu, William G. Wee, Chia Yung Han

Proceedings Volume 2423, Machine Vision Applications in Industrial Inspection III; (1995) https://doi.org/10.1117/12.205514
Event: IS&T/SPIE's Symposium on Electronic Imaging: Science and Technology, 1995, San Jose, CA, United States

Abstract

Cracks occurred in aircraft engine parts have to be detected as early as possible to prevent engine failure. Fluorescent Penetrant Inspection (FPI), that applies fluorescent materials on metallic surfaces for flaw detection, is a generally accepted technology for nondestructive inspection of surface cracks. The major problem with application of FPI technology is the costly false alarms caused by non-crack fluorescence indications (noise), especially when inspecting used engine parts. A novel crack-detection system for automatic FPI of engine parts using image processing and pattern recognition theories is presented. A strong noise reduction capability and a small number of reliable features for pattern recognition are the two primary characteristics of the system, which contains three major modules: noise-reduction and preclassifier module, feature extraction module, and pattern recognition module including four pattern classifiers. An image synthesizing technique is developed to simulate real-world situations by combining the segmented fluorescence images of man-made cracks with the noisy background of fluorescent images captured from actual used parts. The designed system can eliminate over 80% of noise while retain 94% of crack indication. The total error rate using Fisher's linear classifier is less than 3%, with only 4% of crack misclassification.

Citation Download Citation

Yonghong Tang, Aiqun Niu, William G. Wee, and Chia Yung Han "Automated inspection system for detecting metal surface cracks from fluorescent penetrant images", Proc. SPIE 2423, Machine Vision Applications in Industrial Inspection III, (27 March 1995); https://doi.org/10.1117/12.205514

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