Deformation measurements in welded plates based on close-range photogrammetry

A global approach for measuring weld-induced deformations in plated structures is presented in this article. Three-dimensional deformation models of butt-welded plates were obtained before and after three welding tests by using close-range photogrammetry to generate the displacement field from sets of digital images. The procedure was validated against direct measurements of the deformations. A polynomial equation was found to be the best fitting to the surface of a butt-welded plate. Based on the modified Fourier series, a proposed function to represent complex surface was validated. A comparative study on the sampling element size was also included.