An Image-Based Method for Automatic Crack Detection for the Mechanical Test of Clinch Joints

Clinching is a cold forming process for hard-to-weld material's joining in the field of automobile lightweight design and manufacture. The automatic crack detection for clinch joints in the loading test is an important monitor process. In this paper, the method of automatic crack detection on clinch joints by using digital image analysis technology was presented, and an image acquisition and processing platform coupled with a single shear pulling test machine was introduced. In order to insure the real-time of the calculation, multiple scan lines perpendicular to the potential crack strip was set, and threshold segmentation and edge detection with Sobel operator was used in the analysis. Results showed that the analysis procedure proposed in this paper is available for automatic crack detection for the loading of clinch joints and can get high computer speed.