Prediction Of Welding Deformation & Residual Stress By FEM

Simulation of welding distortions in ship sections are performed for the purpose of establishing utility-based design principles. The long-term goal is to specify an optimal welding procedure, and hence, to minimize distortion and residual stresses due to welding. The welding involves multifarious physical phenomena. In this thesis, the potential usefulness of finite element computation and simple analytical and parametric expressions is demonstrated by means of several examples. Inaccuracies arise partly from thermal deformations due to cutting and welding and partly as dimensional variations due to human factors and this increase the production costs.The objective of the present work has been to simulate some typical welding joints. This included establishing an arbitrary movable heat source, measurements of the temperature distribution in a steel plate, calculation of equivalent shrinkage force by inherent strain method measurement of distortions and stresses and finite element analysis by ANSYS.The purpose of the simulation or calculation is to obtain values for in-plane shrinkage and out-of-plane distortion. For the calculation a 3-D model of a plate assuming a 3-D stress field works quite well. The heat source can be moved in straight lines along the plate, by use of the developed simplified APDL subroutine. The FEM results are here in general lower than those experimentally measured. The distortion and stress patterns are fair. Computational welding simulations are not fully established as a science but almost sufficiently developed to be applied to various simplified problems in the heavy industry. The study has shown the advantage of using the inherent strain method for a welding simulation tool, for simple models which can be used as benchmarks.