To improve the energy efficiency, the demand for new light weight solutions has been increased significantly in the last decades. The weight reduction of the current ship structures is possible using thinner plates, i.e. plate thickness between 3 and 4 mm. However, at present this is not possible due to the 5 mm minimum plate thickness requirements given by classification societies. The present paper investigates the fatigue strength of thin plated ship structures. In the European research project BESST-"Breakthrough in European Ship and Ship Building Technologies", the extensive fatigue test programme was carried out for butt and fillet welded specimens, which were manufactured by the arc, laser and laser-hybrid welding methods. The test programme covered also the different production quality, and thus, a large variation of misalignments was included. Fatigue test results were analysed using the nominal as well as the structural stress approach, where the actual geometry of the specimens was taken into account. The results show that the present design S-N curve with slope value of three is applicable to thin plates, but it is slightly non-conservative. The fatigue test results for thin plates show better agreement with the slope value of five. For thin plates and slender ship structures, the secondary bending stress due to angular misalignment plays an important part and changes as the function of the applied tension load. Therefore, it is important to consider the plate straightening effect in structural stress analysis.
|Title of host publication||Analysis and Design of Marine Structures - Proceedings of the 4th International Conference on Marine Structures, MARSTRUCT 2013 : 4th International Congress on Marine Structures|
|Publication date||Mar 2013|
|Publication status||Published - Mar 2013|