Welding deformation control of thin panel block structure using plastic counter-deforming method

Welding is the fundamental process in manufacturing marine structures. Welding deformation is, however, inevitable due to non-uniform distribution of temperature during welding. The deformation due to welding is one of the principal obstacles in enhancing the productivity in manufacturing procedure of marine structures. And this should be much more seriously considered in the case of thin blocks found in ship and offshore structures. This paper is concerned with the deformation control of thin panel blocks. Up to the present, several methods for deformation control have been proposed. In this paper the plastic counter-deforming method has been applied to reduce the welding deformation of thin panel blocks. The counter-deforming method is to deform the panel in the opposite direction to that of welding deformation by using line heating. In order to illustrate the usefulness of the method, welding tests have been carried out for several specimens, and thermo elasto-plastic analysis has been also carried out. The numerical results are compared with those of welding tests. More numerical analysis have been carried with varying affecting parameters to produce the results from which optimum heating condition can be deduced.