Strength Analysis Of Overall Ship FEM Model Based On Design Wave Approach

China is a big ocean country with vast territorial sea and a long coastline. The powerful navy force is needed to protect our country. Even in peace time, a strong naval force can help us attain the objectives that won without battle. If war is unavoidable, powerful navy will play an important role. A huge surface vessel is integral part of navy power. The right strength analysis of naval ship structure is the key for ship design and guaranteeing the safety of the structure.The naval ships have different structural characteristics from conventional ship. She has large openings in the decks and multi-superstructures, which has a tremendous influence on the global longitudinal strength and torsional strength. As a result, navy ship structure can not be considered as a ship beam. This approach is not appropriate for assessing the surface ship.With the development of the finite element method and computer technology, Cabin finite element method appears, and then finite element method of the entire ship has been developed. Deformation and stress of all major components can be calculated through the fem of whole hull. The method is currently the most accurate and perfect method to analysis the hull strength.Determination of wave loads is the key in the strength analysis of overall ship FEM model. Based on linear wave theory, the basic hydrodynamic equations are given for the ship and offshore structures, and the method for calculation of related hydrodynamic parameters and the numerical calculation are presented. At the same time, it gives the long and short term wave predictions methods of ship motion and wave loads based on the spectral analysis and statistical theory. The process of determining the parameters of design waves is given. Furthermore, combined with the long-term wave statistics data, with the use of long-term wave prediction methods and design wave approach, we obtain the design wave parameters under two loading parameters and the associated transient waves in the design wave loads. Determining the ship wave loads with the design wave approach have the advantage of small workload and the method can simulate the real sea condition to get the real wave loads .So that this method makes the finite element results more reasonable.This paper analyses the entire ship strength with finite element model on design wave approach. Finally the paper fixes the high stress area and assess the structural strength of the ship.