This study has been tried to establish the predictive equations for the level of transverse restraint stress and the distribution of transverse residual stress of a thick FCA weldment for the erection stage of a large container carrier using FEA and experiment. In order to do it, the restraint degree of a thick weldment of a large container carrier was evaluated using FEA. The validation of FE analysis procedure used for this study was verified by experiment using an H-slit type specimen for various restraint degrees. In experiment, the restraint stress and residual stress of test specimen were measured using uniaxial strain gages and XRD equipment, respectively. The effects of restraint degree, welding heat input, yield strength of the weldments and welding deposit sequence in a weld groove on the restraint stress and the residual stress were evaluated using FEA. Based on the FEA results, the predictive equations for the level of transverse restraint stress and the distribution of transverse residual stress at a thick weldment were established by dimensional analysis and multiple regression method.
Recently, with an increase in deck plate thickness of a container ship, the concern about the fracture safety of a thick butt weldment has increased more and more. This is mainly attributed to the change of fracture characteristics found at the thick weldment of over 60mm. Up to now, however, the design criteria of fracture properties such as CTOD and crack arrestability toprevent the brittle fracture of a thick weldment are yet to be established. Brittle fracture is associated with the various uncertainties related to loading conditions, material strength, defects, initial imperfections such as distortion and residual stress and so on. Therefore, in order to establish the appropriate countermeasures for the brittle fracture of the thick weldment in the container carrier, first of all, the uncertaintiesdescribed previously should be identified.
