Investigation of the Elastic-Plastic Stress State Around a Reinforced Opening in a Spherical Shell
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CENTER
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A study was made to correlate theoretical stresses and strains in a pressurevessel having a reinforced opening with experimental data obtained for progressive stages of elastic-plastic deformation up to the point of failure. The pressure vessel consisted of a hemispherical dome 12 inches in diameter with a wall thickness of 0.060 inch and a reinforced opening 1 inch in diameter and was machined from 6061 aluminum. The reinforcement was an integrally machined ring 1.70 inches in outer diameter and 0.300 inch thick. In general, there was good agreement between the experimental data and the theoretical results based on true stress - conventional strain data and modified shell dimensions. The conclusion was drawn that the theoretically computed elastic-plastic stresses can be used with the true ultimate tensile strength of the shell material to give a reasonably accurate prediction of the burst pressure. Also, the elastic stress- with the true ultimate tensile strength concentration factor can be used together with true ultimate tensile strength to give a conservative approximation of this burst pressure.
- Metallurgy and Metallography