Study On The Reinforcement Structure Of Pressure Hull Of Submarine With Large Cutout

Due to the requirements of techniques and structure, Pressure Vessels often need to include large cutouts of various types which goes beyond the application of Design by Rules. But because of the changes of the geometry parameters, methods of manufacture and types of loads, it is difficult to calculate the stress and strain in the cylindrical shell structures with large cutouts in theory. Therefore, it is an important subject to analyze the structure systematically and roundly.Among the pressure area method, ASME method, finite element method and methods of design and calculation of submarine structure, the reinforcement calculation method of cylindrical shell with large cutouts was analyzed and compared. The similarities and difference were given. The principle of the calculation formulas of the methods was deduced. The difference was demonstrated by means of this four reinforcement design methods that a cylindrical shell with large cutout was calculated.The shows distribution of the area near by the junction of the coaming and the shell of large coaming-to-cylinder diameter ratio structure are studied. Two kinds of structures namely are studied and compared to each other. The finite element method and the strain-gauging method are applied in this work to investigate the distributions at reinforced area. Some new and valuable conclusions are achieved. The bigger the cutout rate of large cylindrical cutout is, the higher stress that the area of cutout produces. The bending stress at cutout edge is creasing very fast, in excess of 10% of the hoop membrane stress. Therefore, the bending stress should not be ignored but be checked solely.A study of limit loads was carried through three-dimensional nolinear finite element analysis on a coaming on cylinder shell structures subjected to uniform pressure. Models were studied by three-dimension nonlinear finite element method to gain the load-displacement and load-strain curves. By these curves, limit loads was carried out. The value of the limit load reduced with the cutout rate increase. The coaming has a favorable effect on the limit load.