THE INELASTIC BUCKLING STRENGTH OF FABRICATED HY-80 STEEL HEMISPHERICAL SHELLS
Research and development rept.
DAVID W TAYLOR NAVAL SHIP RESEARCH AND DEVELOPMENT CENTER BETHESDA MD STRUCTURES DEPT
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Eight, 66-in.-diameter, fabricated HY-80 steel hemispherical shells designed to fail by inelastic buckling were tested to observe the effects of initial imperfections and residual stresses on elastic behavior and collapse strength. The results demonstrate that the effect of secondary moments and residual stresses on collapse strength diminish as the ratio of elastic to inelastic buckling pressure increases. It was possible to predict the collapse pressures of these models within 10 or -10 percent by utilizing imperfection analysis and extrapolating previous test results of less stable shells. Fairly good agreement was also obtained by using the same imperfection analysis to predict the membrane stresses in the center of the flat spots. Addition of the results of these tests to those obtained on shells in the less stable regions provides a basis for a reasonable collapse equation for practical spherical shells over the range of shell stability of interest to deep submergence.