Research On Stress And Deform Of Shipbuilding Dependent Processes

Improving manufacturing accuracy, reduce the production costs and increasing labor productivity are inevitable results and requests of the development of shipbuilding. It is an important method for advancing shipbuilding quality to improve shipbuilding processes. Research on technic of shipbuilding processes is the foundation of improve shipbuilding processes. Therefore, research on technic of shipbuilding processes is essential. In this study, researches on three shipbuilding key processes are performed.(1) Research on Dead Load Forming of Hull Steel PlatesThe relatively large deflections of sheet are described and the models of finite element method are built and checked up by experimental measure of dead load forming. The database of the calculations for dead load forming of hull steel plates is established. Data of effective parameters are measured, and the effect principles of the primary parameters such as length, width, thickness, and radius are qualitatively analyzed. With curve estimate and multi-variable stepwise regression analysis methods, mathematical models for the dead load forming of hull steel plates based on the primary parameters such as length, width, thickness are presented.. Based on above algorithm, and combined with shipyard production condition, a forecasting system is developed for the dead load forming of hull saddle shaped steel plates. Factual plate tests in shipyard production show a forming precision of this system.(2) Research on technic of ship superstructure's integral assemblyFirst, ship superstructure's integral assembly (SSIA) is an advance process, but still a hard nut, in ship construction. In this study, taken 12,600 tons oil tanker as an example, the arrangement of lifting padeyes in SSIA is analyzed with the theory of structure strength and finite element method (FEM). Base on the strength analysis, a new hanger of SSIA is invented and the credibility of design is verified. Some basic regulations of SSIA are found.Secondly, strength Analysis methods of Lifting Padeye are developed. In the paper, the external loads on the padeyes are analyzed and a robust stress check formula is derived using curved beam theory. The results of finite element method (FEM) and the solutions of traditional check formula and new check formula are compared. It is shown that the new expressions account for a better representation of the real stress value and distribution. By applying the strength check formula presented in the paper, the safe reliability of structure design can be improved significantly. (3) Research on technic of cutting hatch openings in ship structureNumerical analysis of cutting in ship structure is performed. This study applies thermal elastoplastic analysis, using finite element techniques, to build a model for the temperature distribution during cutting and stress distribution in the workpiece. A non-contact temperature method—Infrared Radiation (IR) is used for surface temperature measurement. The residual stresses at the surface of the workpiece were measured by impact-indentation measurement. The results of finite element analysis were compared with experimental results to confirm the accuracy of the method. Numerical experiment of cutting hatch in flat plate is put up, and the effect principles of the primary parameters such as length of cutting line, bound condition, size of steel plate, the form of hatch, position of hatch are analyzed. On this basis, numerical analysis of cutting in ship structure is performed and the deformation and stress are analyzed.