Research On The Law Of Welding Distortions Of Typical Ship Panel Structure

Welding technology is one of the key technologies in the process of ship construction. The level of welding largely determines the quality of the construction of the hull, the generating cycle and the production costs. But it is difficult to control the welding distortion in the welding process. The existence of welding distortion will cause the mutation of structure shape, the decrease of precision and the reduction of load capacity. Therefore, it has become an urgent problem to prediction the welding distortion in shipbuilding industry. Taking the typical panel structure in the shipbuilding process as the research object, the impacts of various factors on the welding distortion was analyzed using thermo-elastic-plastic finite element method in this paper.Firstly, nonlinear finite element method was used to simulate the welding process of eight-rib structure with the commercial software MSC.MARC. The thermo-mechanics parameters changing with temperature and the high accuracy heat source model of double elliptical are utilized to compare the influence of material properties on the welding distortion. Material properties parameters include four mechanical parameters:yield stress, elasticity modulus, Poisson’s ratio, coefficient of thermal expansion, and three thermal parameters: thermal conductivity, specific heat capacity and density. Secondly, the effects of welding parameter on transverse shrinkage are also studied. It conclude that:(a) welding shrinkage decreases with the increasing of the plate thickness,(b) welding shrinkage increases with the increasing of heat source power,(c) welding shrinkage decreases with the increasing of welding speed,(d) with the increase of welding heat input the welding distortion present a linear increase,(e) welding shrinkage increases with the increasing of ambient temperature.Finally, The same method are conducted to simulate the welding process on five different typical welded structure:single-rib structure, double-rib structure, three-rib structure, four-rib structure, eight-rib structure respectively. Analysis model was established to quantitatively describe the influence of welding sequence on welding deformation. The results show that compared with the method double-seam welding at the same time, when welding was conducted continuously from one side to the other side, the transverse distortion can be reduced by8%.