In situ strain monitoring in gas tungsten arc welding processes

Strain/stress evolution during welding is essential to understand material's mechanical behavior and the formation of weld defects such as distortion, cracks and residual stresses. In-situ measurement of strain has been very challenging due to the impact from high temperature and intense arc light. In this work, a newly-developed integrated optical system was utilized to monitor material's thermal and strain field adjacent to the fusion line during GTAW process. It was found that the variation of the measurement data could be positively correlated to the change of welding parameters and the characteristics of the final weldment. The purpose of this work is to develop a real-time welding quality monitoring system to proactively prevent the formation of certain weld defects.