Welding is a process to join metals with different arrangements of the plates. In the shipbuilding industry, the joining of plates in such a way as to ensure higher productivity is very important, but the industry has been facing the problem of deformation for seven decades. The shipbuilding industry is trying to control this problem, but thin plates bring non-linear problems in the structure, especially in the bulkhead of the structure that leads to more deformation due to small members of the profiles. This problem occurs in the construction of yachts because clients need good outlook of the ship. To control this problem the computational analysis is the more productive method than other to solve this deformation problem. The thermal elastic plastic FEM method is used to analyse the thermal and mechanical problems. This analysis confirmed that this TEP-Finite Element Method is applicable for the control of deformation in the thin plate.

During fabrication process, material deformations are likely to occur due to various factors such as heat during steel cutting, welding induced deformations, lifting and turning of ship sections, temporary stiffening and other possible modifications of ship sections. Lifting induced deformations is one of the major causes of deformations that highly affect the production cost and quality. The aim of this thesis is to outline the main causes of deformations that occur in ship sections during fabrication and to analyse in detail the lifting and turning operations of one ship section using the Finite Element Method (FEM). A strength check using the FEM has been performed on the selected ship section to investigate the deformations and stresses in two different cases with three different loading conditions. First, the section has been analysed without temporary stiffening in three load scenarios: lifting before turning, worst-case scenario during turning and lifting after turning. Similarly, the second case study has been analysed but with the temporary stiffening added according to the lifting plan. Various influencing parameters that determine the lifting plan has been investigated such as the sling angle which directly affects the deformation characteristics. It is observed that the addition of temporary stiffening is essential to minimize the deformations and to maintain the stress levels below the yield point.