In-situ strain measurement and error analysis of arc welding with 2D digital image correlation

The deformation and residual stress generated by the welding process can seriously affect the use of components. As a result, it is very important to understand the evolution of stress and strain during the welding process. The strain measurement method based on digital image correlation (DIC) is an excellent method to detect welding strain and residual stress. The out-of-plane translation and out-of-plane rotation introduce errors to the two-dimensional DIC. In this paper, the causes of errors are analyzed theoretically, and the formulas of errors caused by the out-of-plane displacement and the out-of-plane rotation are derived. The out-of-plane translation experiment and the out-of-plane rotation experiment were carried out to verify the theory , and the experimental results are consistent with the theoretical analysis results. The error caused by the out-of-plane translation can be reduced by increasing the object distance; the error caused by the out-of-plane rotation is greatly affected by the rotation angle.