Structural Analysis of a Full-Scale Spherical Acrylic Plastic Pressure Hull.
Final technical rept. Jul 69-Jun 70,
NAVAL CIVIL ENGINEERING LAB PORT HUENEME CA
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Analysis of a design of a pressure hull incorporating 12 spherical pentagons of acrylic plastic bonded together to form a sphere with an outside diameter of 66 inches and a wall thickness of 2.5 inches. Steel penetrations were located at the two poles. The experimental results were obtained from strain gage data from two independent pressure tests to 500 psi on two acrylic plastic hulls of the same design. The finite element analysis of the hull structure placed particular emphasis on the acrylic plastic-steel boundary. The boundary conditions at the acrylic plastic-steel interface were two extreme cases fixed and free. A time-dependent yield-failure criterion for acrylic plastic was combined with the structural analysis to provide an operating depth curve as a function of both time and temperature. Comparison of the finite element and experimental results indicated excellent agreement. At a temperature of 70 F and a maximum of 50 hours load duration, the acrylic plastic hull can operate to 1,000 feet with a safety factor of 1.5 based on yield and a safety factor of 2.6 based on collapse. Design recommendations are also presented to provide guidelines for future design of the hull and its integration with an undersea vehicle. Author, modified-PL
- Marine Engineering