Research Of Fatigue Strength On Common Structural Rules Of Bulk Carriers And Its Joint Structure

The ship is sailing on the sea, the sea waves and internal cargo ship inertial force to sail inthe sea which is when the load changes at any time, and this will makes the ship structure is infor a long time under the alternate load, the parts of stress concentration will gradually formsmall cracks, then continues to expand, eventually causing brittle fracture, which consists ofalternating load caused by cumulative effects is fatigue failure. An overview of modernmarine accident, with the hull to large-scale development, the proportion of accidents causedby fatigue failure is increasing. Therefore, research of the fatigue strength on the key parts isvery necessary, and it has certain instruction function to the ship structural design and safetyassurance. Ship fatigue strength mainly refers to the ship structure node resistance alternatingstress and reduce the growth rate of cracks. Therefore, to improve the fatigue strength ismainly improved structure node connection form, avoid excessive stress concentration.This article mainly aims at the 《CSR》for fatigue strength theory and method undertookstudy, the main contents are as follows:1） Analysis and Research on the fatigue reliability of the various principles and methods(S-N curves and fracture mechanics method), including fatigue load and fatigue strengthprobability model, fatigue life reliability prediction.2） Study 《CSR》for fatigue assessment analysis method, including the finite elementmodeling, fatigue detail mesh generation, boundary conditions, loading and fatigue lifecalculation, and the CCS《hull structure fatigue strength guide》for comparison, analyzing itsadvantages and disadvantages;3） Based on the FEM fatigue assessment method of ship structure, analyse some hotspot node form, raise some improvement and comparative analysis, that member has a smoothgeometry of the free edge member as the stress transmission media, including soft toe, softboard, can effectively to reduce the stress level. And with a82000DWT bulk carrier in asexample, according to《CSR》 for fatigue assessment calculation, and compare with the resultof《hull structure fatigue strength calculation of guide》, study the different componentsconnected on the structure fatigue strength contribution.