Research On Adjusting Loads For Direct Calculation Of Strength To The Whole Hull's Structure

It's always difficult to carry on accurate strength analysis and calculation for the hull structure in design and inspection of the ship's structure due to the complexity of the structure and the loadings on it. The traditional method is to consider the hull as a beam and this way is too approximate. Nowadays, when new typed ship being built, their hull structures become more complicated, and the shortcoming of the traditional analytical way is being concerned gradually.However, as hardware technologies of computer develop, it becomes possible to divide the local structure or even the whole ship into finite elements for analysis. Thus, it brings revolutionary break to the strength analysis for hull structures. When all the ship classification societies in the world are seeking a suitable and reliable new design method, the direct calculation method is becoming popular.The finite element analysis is based on a finite element model which could be set up by using the finite element software, in which several types of elements such as elements of membrane, rod, plate, shell and beam are used in light of the actual force acting upon the structural members. The distribution displacement and stresses of the primary members' can be calculated. This method is the most accurate and perfect way to analyse the hull structure at present, and it's also the most accurate way to forecast the response which caused by loads in rational structure design.This paper investigates the whole hull structure's strength calculation for a 110m river-to-sea bulk carrier, using the finite element calculation software MSC.Patran and MSC.Nastran. The cargo loadings are calculated according to the Guidelines for Direct Calculations of Strength of Bulk Carrier, 2003 (CCS), and wave loadings are calculated directly by SCLOS (Structural Calculation system of the Large Opening Ships) software, while the allowable stress in structure strength evaluation are selected according to Guidelines for Direct Calculations of Strength of Bulk Carrier, 2003 (CCS).Wave loadings are very important in the design of the ship structure. The correct calculation for wave loadings is necessary to assure the correct results in the whole ship's quasi-static state condition analysis, as well as the balance situation with the ship weight. The prelimary and accurate adjusting method of the loadings acting in the structural strength analysis are studied in the thesis, and the results from the two methods of the calculation are compared and analyzed.