Application of Moiré interferometry to study residual deformation in lap-welded steel plates

Moiré interferometry combined with hole-drilling is an effective method for measuring welding residual deformation. In this study, two lap-welded rectangular steel plates with different overlap widths were manufactured, and cross-gratings with a frequency of 1200 lines per mm were replicated on test areas of the welds. Sixteen through holes were drilled in the plates to release residual stress, while Moiré interferometry, integrated with a phase-shifting technique, was used to determine the corresponding surface residual deformation. The distribution characteristics of the residual displacements around the drilled holes were investigated using the experimental data as basis. The relationship between the residual displacement located in the plates and the distance to the weld lines is also presented in this paper. Furthermore, the magnitude and direction of the residual strain both near the holes and within the plates were analysed. The experimental data and detailed analysis in this paper can serve as some reference for research on the residual strain of welds.