Direct Calculation Of Bulk Carrier Structure Strength And Research Of Strength Criterion

The strength of ship structure is the main .factor that affects the safety of ship ocean transportation. For the increasing of ship dimensions and new type ship building, every ship's class society is searching for reasonable and reliable new design method. Then ship structural direct calculation method comes to occur, and every ship's class society takes it into use. Usually, direct calculation must be carried out for the bulkcarrier that the length is more than 190m or the structure is complex. But in calculation, they have difference. This article main purpose is to analyze the different boundary condition how to affect the stress result.This article first elaborates the ship structure direct calculation concrete methods and regulations of CCS, DNV, LR and GL. These four ship's class societies all use two holds length finite element modal near the central section. They mesh the finite element modal mainly according to the distance of longitudinal frames, we call this fine mesh finite element modal. The elements in the modal are mainly shells and beams. The difference is the calculation of external force, specially the methods of dealing with boundary conditions. Moreover it lists the permit stress of CCS, DNV, LR and GL to analyze results.This article gives a discussion that is methods and demands of CCS, DNV, LR and GL in modeling. We modeled a 150000DWT bulkcarrier and chosed 8 working conditions according to "load manual" and "CCS bulkcarrier direct calculation note". In calculating load, this article only uses the load calculation formula of CCS.This article discusses every method in dealing with boundary conditions of CCS, DNV, LR and GL.This article calculates the finite element modal using the different boundary condition of CCS, DNV, LR and GL, compares the calculation result with the permit stress to prove the safety of structure and Then analyzes the results and comes to conclusion. From the conclusion, we can know the results can give a same judgment of ship structure safety, adding end shear force can little increase the stress and multi linear adding may make the result worse.