Research On The Fatigue Strength Assessment Approach For Sea-river Going Ship

Sea-river going ship is convenient and efficient and play an irreplaceable role in Chinese development.Compared with the traditional ships,the sea-river going ship encounter the environmental loadings caused by both river and sea,and their structures should safety the requirements from both river and sea rules during the sailing from river to sea.However,we usually use the requirements specialize for sea ships to evaluate the fatigue strength of sea-river going ship,which may lead to conservative ship structures.Therefore,it is necessary to carry out a systematic study on fatigue strength assessment on sea-river going ship.A sea-river going ship was choosed as an example in order to study the fatigue strength assessment approach.First,the SESAM software was used to calculate the ship wave loading in several typical loading conditions for the ship,and both short-term and long-range forecasting were obtained.The whole ship structure has been direct analyzed based on the design wave method;and the stress and deformation of the ship were obtained.Then,according to CCS,DNV and CSR specifications,the simplified fatigue calculations on the sea-river going ship were carried out and compared.Finally,a local finite element model of the structural hot spot was built;and spectrum fatigue analysis was implemented with consideration of the loading characteristics of the sea-river going ship.The simplified fatigue method and spectrum fatigue method are used in this thesis to check the fatigue strength of a sea-river going ship.The spectrum fatigue method showed a smaller prediction which is closer to the true.The research work can be used as reference to the fatigue strength for similar ships,and the direct fatigue strength analysis demonstrated in this thesis can be significance for the other ships.