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— In the field of structural mechanics the word shell refers to a spatial, curved structural memb... more — In the field of structural mechanics the word shell refers to a spatial, curved structural member. In shells, the external loads are carried by both membrane and bending response. The effect of such responses needs careful observation. This project fulfills the need on study of behavior of shell structures by both mathematical and numerical methods. In the present development, the Donnell's relation forms the basis of stability equation for circular cylindrical shells. The effect of stiffeners on cylindrical structures has been studied, by varying the geometry and orientation of stiffeners. The paper aims to analyze the cylindrical section of an underwater pressure hull, using finite element analysis and strengthen it accordingly. The project considers the finite element method for static structural and deflection analysis of underwater cylindrical structure by using ANSYS 15software. Keywords— critical buckling load or load multiplier, Finite Element Analysis, Pressure Hull, Donell's relation, stiffened cylinders. I. INTRODUCTION Many theoretical studies have been done in cylindrical structures by considering the cylinder as thin, and the stress variation in the direction of thickness as negligible. This research project intends to combine the classic shell theories with the contemporary numerical approach and this thesis primarily focused into, large thickness variation by considering cylinder as thin, moderately thick as well as thick by varying, l/d and r/t ratio. This thesis evaluates the critical buckling load of cylindrical shells subjected to external pressure. The Donnell's relation forms the basis for stability analyses in the literature than any other set of cylindrical shell equation. The finite element modelling of the structure can be done with Ansys Workbench 15. The check for accuracy can be made by comparing the results of both numerical and mathematical method. The load carrying capacity of cylindrical structures can be improved by adding stiffeners, the analysis in variation of stiffener geometry and orientation can be done by considering the cylinder as externally stiffened, internally stiffened and spirally stiffened. The design of a pressure hull is made to withstand an external pressure of 65 bar (according to ASME standard) is analysed and an improved design of pressure hull is suggested to withstand such load with minimum deformation is obtained.
— In the field of structural mechanics the word shell refers to a spatial, curved structural memb... more — In the field of structural mechanics the word shell refers to a spatial, curved structural member. In shells, the external loads are carried by both membrane and bending response. The effect of such responses needs careful observation. This project fulfills the need on study of behavior of shell structures by both mathematical and numerical methods. In the present development, the Donnell's relation forms the basis of stability equation for circular cylindrical shells. The effect of stiffeners on cylindrical structures has been studied, by varying the geometry and orientation of stiffeners. The paper aims to analyze the cylindrical section of an underwater pressure hull, using finite element analysis and strengthen it accordingly. The project considers the finite element method for static structural and deflection analysis of underwater cylindrical structure by using ANSYS 15software. Keywords— critical buckling load or load multiplier, Finite Element Analysis, Pressure Hull, Donell's relation, stiffened cylinders. I. INTRODUCTION Many theoretical studies have been done in cylindrical structures by considering the cylinder as thin, and the stress variation in the direction of thickness as negligible. This research project intends to combine the classic shell theories with the contemporary numerical approach and this thesis primarily focused into, large thickness variation by considering cylinder as thin, moderately thick as well as thick by varying, l/d and r/t ratio. This thesis evaluates the critical buckling load of cylindrical shells subjected to external pressure. The Donnell's relation forms the basis for stability analyses in the literature than any other set of cylindrical shell equation. The finite element modelling of the structure can be done with Ansys Workbench 15. The check for accuracy can be made by comparing the results of both numerical and mathematical method. The load carrying capacity of cylindrical structures can be improved by adding stiffeners, the analysis in variation of stiffener geometry and orientation can be done by considering the cylinder as externally stiffened, internally stiffened and spirally stiffened. The design of a pressure hull is made to withstand an external pressure of 65 bar (according to ASME standard) is analysed and an improved design of pressure hull is suggested to withstand such load with minimum deformation is obtained.