Fatigue Strength Assessment And Test Research On The Structure Of Multideck Ship

Compared with conventional ship, the multideck ship contained complex ship structure and multipliex sailing loadcases. Fatigue problem of multideck ship was more serious. At present the fatigue problems of ship structure had been deep researched,but the research mainly focused on conventional ship. As to multideck ship, few studies of structural design and fatigue strength analysis can be found, and few design rules can be followed. In the dissertation,the method of simplified process and spectral-based fatigue analyses suitable for multideck ship structure were researched with a replenishment ship as an example. The real thickness fatigue test of multideck ship's typical structure was done. The main contents were as follows:1) The differences between the simplified method presented by CCS and DNV rules were analysed. The fatigue strength of multideck ship structure was assessed by the simplified method.2) The multideck ship had complex structure and legion typical spots. In the dissertation,the kind of spots which had serious fatigue problem was screened with coarse mesh based on the spectral analysis,and the fatigue strength of spots was assessed with fine mesh.3) On the basis of whole ship structure's fatigue analysis, the positions of ship superstructure end and corner which had serious fatigue problems were determined , and real thinkness fatigue model tests were designed. The fatigue life of specimens' was obtained under different load levels.4) The probability statistical method was used to precesse the fatigue test dates, and the S-N cuvers characteristic of test spots were obtained. The fatigue strength of research positions were calculated and compared under the fatigue testing P-S-N curve and the E curve of CCS rules.