| Fatigue damage is considered to be very common in ship and offshore structures. River-sea ship is encouraged to be researched further in our country during recent years. This type of ship is of shallow draft and wide breadth, subjected to different wave loads of river and sea; its hull structure requirement is lower than sea ship and higher than river ship. Fatigue strength of this ship type's structure needs further investigation. Based on the background above, a 521 TEU container ship is taken to be the research object in this thesis. Hydrodynamic analysis, strength checking and fatigue study on it are carried out. The main research content includes the following three aspects:(1) Based on 3D potential theory, hydrodynamic analysis is carried out on specific routes river-sea ship to obtain the transfer function of motion and sectional load; Wave loads of exceedance probability 10-7.5 along ship length with zero speed are forecasted, the influence of different loading conditions and sea areas on long-term wave load are researched; the forward speed effects on wave load is discussed under low speed.(2) According to the results of long-term forecast of load control parameters, based on the deterministic design wave method, the most dangerous waves that river-sea ship would suffer are obtained. Apply the designed waves on finite element model, the stress and displacement distribution on ship hull are obtained.(3) The fatigue strength of river-sea ship is studied using China's coastal long-term wave data based on full stochastic analysis, and the fatigue damage of different locations under different load conditions are studied. The influences of hotspot setting and short-crested wave on the fatigue are discussed; Fatigue damage distribution of each checkpoint over short-term sea condition is mainly researched, fatigue damage distribution over wave height, wave period and wave direction are obtained. Lastly, the influence of inland river wave on fatigue of river-sea ship is researched. |
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