A study on the type-b hot spot stress

Abstract

Stress distributions in the vicinity of type-b hot spot in the in-plane gusset welded joints and in the free edge of the stiffened cruciform welded joints were evaluated according to the solid model, the fine mesh shell model, and the coarse mesh shell model. The hot spot stress (HSS) of each FE model was evaluated by extrapolating the stresses at the read out point (ROP) to the hot spot position according to the recommendations of IIW and were compared. Regarding the in-plane gusset welded joints, it is confirmed that the HSS by the solid model and the shell model are corresponding in the case of in-plane notch in which the thicknesses of the main plate and the gusset plate are same. It is observed that the shell model estimates lower HSS than that by the solid model when the main plate is thicker than the gusset plate. The reason of this difference is considered that the shell model does not evaluate the stress distribution in the thickness direction of the main plate in front of the in-plane gusset plate but evaluate the averaging stress. A simple correction factor to the HSS evaluated by the shell model based on the ratio of both plate thicknesses was examined. Regarding the free edge of the loaded attached plate in the stiffened cruciform welded joints, it is confirmed that the hot spot is on the corner edge of the attached plate. It is observed that the shell model estimates lower HSS than that by the solid model.