Prediction of welding deformations of large stiffened panels using average plastic strain method

Curved or flat stiffened steel panels used in ships and offshore structures are fabricated mainly by fusion welding. It leads to heat induced plastic strains, distortions and residual stresses. These distortions may adversely affect the subsequent fit-up and alignment of the adjacent panels. A solution methodology named average plastic strain method was developed and adopted based on evaluation of average plastic strains of butt and fillet joints of small scale specimens. These were obtained using the conventional thermomechanical analysis. These plastic strains were then used to determine the overall distortions of large stiffened plate panels. The results obtained were compared with those of established inherent strain method for prediction of distortion of large stiffened plate panels. Computational efficiency of the average plastic strain method was found to be comparable with the inherent strain method. However, the accuracy in the plastic strain method was found to be better than that in the inherent strain method.