Welding Effects On Thin Stiffened Panels

Abstract

The major problems due to welding effects are the residual stresses and distortions of which the levels affect more or less the resistance and lifetime of welded structure. In steel industry and particularly in shipbuilding, during these last few decades, thin plates are used more and more in ship construction in order to lighten the structure weight. Unfortunately, excessive distortions occurred on these thin stiffened panels and straightening works must be executed in respecting the limit tolerance fixed by the Quality Standard of Ship Construction. These futil works reduce Productivity and Quality, increase Construction Cost and get longer Fabrication Delay. Thus, it is necessary to evaluate, control and minimize the distortion and stress levels of thin welded panels before welding assembly operations. In this paper, a short presentation of the Methodology and its industrial applications in shipbuilding are presented for two panels of a Chemical Parcel Tanker (1996) and a large "Testing" Panel in full scale of a Passsengers Ship (2002). The numerical results due to welding effects so obtained within short computer-time (three hours and half for a 3D FE model of more than two million of degrees of freedom) ) on a linear FEM software were verified with measured stress values and identified with the buckling state of the "Testing" Panel before and after welding operations by photographies.