Numerical Simulation to Investigate the Influence of Welding Sequences and Boundary Conditions on the Mechanical Behaviour of Gusset Joints

Welding is one of the most widely used joining processes for the fabrication of steel parts. Consequently, it is commonly used in the shipbuilding industry for the fabrication of structural T-stiffeners. However, this process introduces inherent imperfections, such as angular deformation and residual stresses, which can affect structural stability and shorten the lifespan of the parts. This study conducts a literature review to replicate numerical analyses from reference studies, validating the proposed simulation methodology by comparing numerical and experimental thermo-mechanical results. A finite element model is created using MSC Patran and the welding process is simulated with Simufact Welding. Once the methodology is validated, a case study is conducted in which the shielded metal arc welding (SMAW) process is simulated using a simultaneously coupled thermo-elasto-plastic analysis, based on the finite element method. The study aims to determine the influence of welding sequences and mechanical boundary conditions on angular deformation and longitudinal residual stresses in the T-joints of narrow and thin plates made of S355J2 structural steel. These plates are used as structural stiffeners in the stern and bow sections of patrol boats. The goal is to propose an optimal welding sequence and boundary condition configuration that mitigates angular distortion and longitudinal residual stresses in the structural members. The proposed welding sequence consists of four weld lines running from the middle of the plate to the end, whilst the mechanical boundary condition supports the plate along the longitudinal ends.