Finite element analysis of temperature and stress fields in butt welding
Ng, Vervin Jun Hao
Date of Issue2016
School of Mechanical and Aerospace Engineering
During a welding process, intensively localized heat input and sharp temperature gradient often occur, generating stress and distortions to components. These distortions and deformations can cause misalignment and dimensional inaccuracies during the assembly of marine structures where rectification could be costly and difficult. Submerged arc welding is one of the most commonly used welding processes for marine architecture due to their high deposition rate and high quality weld. In this study, a 12mm thick ASTM A36 corrugated steel plate is selected as the experimental material. A combination of finite element method is carried out on transient thermal and structural analysis using ANSYS Parametric Design Language code. In this model, a moving heat source replicating a welding torch with heat distribution is first simulated in the thermal analysis to illustrate the heat generated on the material during the course of welding. Thermal history is then retrieved and converted into physical body forces to be applied in the structural analysis. The heat transfer effect based on past literature which consists of heat conduction and natural convection has been considered. Results extracted from thermal analysis indicate slow cooling rate along weld line due to the possible assumptions made by the author. Conclusion drawn from the structural analysis showed that both maximum stress and displacement occurs toward the rear of the plate. In addition, the author also found that the material will continue to deform during cooling, while stress level decreases. Future works could be to include other factors such as radiation and forced convection to verify the significant of these heat transfers during the cooling process.
Final Year Project (FYP)
Nanyang Technological University