The aim of this study is using finite element method (FEM) to develop a computer aided engineering (CAE) technique for calculating temperature and stress distributions in large-plate welding. From the stress distribution, the maximum tensile residual stress can be predicted which is the most critical parameter in determining the structural integrity of large-plate weldments. Experimental measurements of temperature are carried out to validate the FEM simulation. Hopefully, the developed CAE technique and validated FEM model could help plan a better welding process for large-plate welding and improve its structural robustness. A double ellipsoidal volumetric heat source is employed in the FEM model to simulate large-plate welding. The simulated variation of temperature at selected positions is compared with experimental measurements to verify the effectiveness of the FEM modeling developed. The thermal history at selected positions shows a similar trend between simulations and experiments. In particular, simulation results of temperature variation concur with one of the three given experiments. At the melt pool area after the welding and cooling process, von-Mises equivalent stress is much larger than that at the edge of plate. The maximum residual stress (in von-Mises equivalent form) is located at the melt pool area and has a value of 294 MPa which is close to the yield strength (290 MPa). Therefore, plastic deformation is expected to take place around this highly stressed region. The magnitude of residual stress decreases with increasing distance from the melt pool area and heat affected zone. Higher compressive residual stress is concentrated at the starting and ending regions on the welding path, for the normal stress component (xx) in the direction perpendicular to the welding path. For the normal stress component (yy) in the direction parallel to the welding path, larger tensile residual stress is located at the melt pool area and it becomes compressive stress at the region away from the welding path.
