Measurement of the Welding Full-Field Deformation of the Sheet Material with Different Curvature Based on Digital Image Correlation

It is of difficulties in measuring welding deformation because of high temperature and the light intensity. In this paper the traditional welding deformation measurement method are reviewed,and the features and limitations of each method were analyzed,and then focused on the non-contact optical measurement method based on the WDIC. In this paper, a noncontact measurement method based on WDIC (weak digital image correlation) is proposed to obtain full-field buckling deformation in the whole welding and cooling process. And the matching difficulties which are caused by weak speckle performance and the large deformation around the solder joint are overcome through the method of piecewise benchmarks based on the continuity of adjacent states. Based on the above methods, the experiment of the sheets welding with three different curvatures was carried on and the following conclusions are summarized based on the analysis of the buckling deformation. The formation mechanisms of out-of-plane deformation in welding area were clarified based on the experimental results. First, low carbon steel occurs buckling deformation with dish shape in welding process and saddle shape in cooling process. Second, the curvature of the sheet has a great influence on the result of the welding. The sheet with a bigger curvature has the smaller displacement in Z direction in the welding process and the smaller transverse strain in the area adjacent to the welding seam. Those measuring results can be used to analyze the influence factors of welding deformation, control the welding deformation and verify the welding numerical simulation.