Comparison between finite elements simulation of residual stress and computer vision measurements in a welding TIG process

In this work, residual stresses arising after an industrial TIG welding process on an aerospace grade part are investigated. The customer demand for high product resistance and high dimensional accuracy calls for the control of the welding process and the minimisation of the residual stresses. Dimensional check of manufactured parts was traditionally performed in a quality room by means of coordinate measuring machines (CMM). For parts larger than 1 meter, this operation shows several issues, as the handling and the need for large and expensive measuring devices. These needs can be fulfilled by an innovative method that, through continuous dimensional check, allows to optimise the welding process parameters. This method is built on a post-process measurement of part shrinkage based on a Computer Vision technique, the outcome being a 3D reconstruction of the actual part. Moreover, the whole procedure is low-cost and time saving, as it can be performed with a conventional camera mounted on a tripod. A Finite Element Model (FEM) of the TIG process on the selected sample was developed. The result of the numerical model was compared with the Computer Vision-based post-process measurement. The simulation scenario predicted by Finite Element Analysis agrees with measurements.