Numerical Investigation on the Effect of Thermo-mechanical Tensioning on the Residual Stresses in Thin Stiffened Panels

In shipbuilding industry, thin plates are widely used to maintain the minimum hull weight and to increase the fuel efficiency. These thin plates, when welded, are more prone to buckling distortions. So, it is very much important to predict these buckling distortions beforehand and try to mitigate them in the fabrication stage rather than doing it later. By doing this, the competitiveness in cost and time can be increased. In this study, a numerical investigation on the reduction of buckling distortions in the fabrication of orthogonal stiffened panels as used in shipbuilding was conducted. A method of in-process distortion mitigation technique, named as thermo-mechanical tensioning (TMT) was introduced to reduce the compressive residual stress in the far-field zone. The detail stress development mechanism in TMT process is discussed here. Commercially available finite element software ANSYS (R) 15 was used for calculations. The simulations revealed that the peak tensile stresses in the weld zone and the corresponding far-field compressive residual stresses get significantly reduced by the implementation of TMT. Thus, with reduction of compressive residual stress, buckling of such stiffened panels is effectively mitigated.