Measurement of sheet welding buckling deformation

Buckling distortion of sheet is inevitable and difficult to correct in welding process. Using advanced measurement method to obtain the buckling law and reveal the mechanism of welding buckling deformation has many difficulties. This paper aims to realize full-field buckling distortion measurement in welding and cooling process based on a noncontact way with digital image correlation (DIC) technology. First, a new algorithm was proposed to match corresponding points which was suitable for low correlation and large distortion. Second, an experimental platform was set up for both sheet welding and measuring with DIC measurement system. Finally, the distorted data were analyzed to reveal the buckling law by bead-on-plate welding experiment. The experimental results demonstrate that low carbon steel would form buckling distortion in welding and cooling process, showing disc and saddle shapes, respectively. The inherent strain mainly distributed around the weld, and the longitudinal contraction of weld was the main reason for plastic buckling. The experiments for welding buckling law could not only verify the prediction theory of welding distortion based on finite element numerical simulation, but also provide the basis and thinking for welding correction methods. The buckling measurement based on DIC plays a positive guiding and promoting role in developing sheet welding process.