Online welding process monitoring using multi-optical sensing techniques (Conference Presentation)

The increasing need for improvement of weld quality and productivity requires advanced welding monitoring and control technologies. In our research, a multi-optical sensing approach is utilized to maximize the effectiveness of reliable weld flaw detection and real-time adaptive feedback control of welding conditions to eliminate the formation of weld defects. Weld pool characteristics and strain-stress evolution in the heat affected zone, two factors that closely related to certain weld defects are monitored. The sensing system mainly consists of a digital camera synchronized with a laser-based illumination and filtering system to suppress the strong arc light so that the weld pool and the surrounding region can be clearly visualized to measure the weld pool surface dimension and estimate the penetration depth. The strain evolution and the weld distortion in the heat affected zone can also be monitored by digital image correlation (DIC) method with the assistance of the recently developed high-temperature speckle preparation method. In additional, a procedure has been developed to determine the stress evolution in real time.