The fatigue performance of YP47 welded joints has been investigated by means of extensive fatigue tests accompanied by numerical investigations. As a major result of the investigations it has been found that YP47 joints show a good fatigue performance covered by the present rules and guidelines. A comparison between different common fatigue assessment approaches showed some inconsistencies and need for further adjustment. While the current procedure for the consideration of the thickness effect could be confirmed for butt welds need for modification was found for attachments in this respect. In contrast to the procedure of the relevant rules and guidelines a clear influence of the material's yield strength on the fatigue strength could be observed for welded joints.
The trend towards highly utilized structures and increased sizes of container ships, mainly driven by economy of scale effects, is accompanied by extensive application of high tensile strength steels in order to keep the plate thicknesses within acceptable limits. Materials with nominal yield strength of 460 N/mm2 called YP47 and plate thicknesses of up to 80 mm characterize this development. Due to the combination of high strength materials, thick plates and high cyclic loads, fatigue becomes one of the major design parameters, especially for welded joints. In this respect the thickness and the material's yield strength effects also for welded joints gain significance. Against this background an extensive fatigue test program was set up accompanied by fatigue strength prediction calculations according to the common fatigue approaches i.e. nominal, structural or hot-spot and notch stress approach. Beside the main objective, the investigation of the fatigue performance of YP47 welds, further investigations of the thickness effect, the material influence and the prediction quality of the different fatigue approaches were defined as objectives of the activities.
