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The Axisymmetric Buckling of Initially Imperfect Complete Spherical Shells.

AD671833

Publication Date	1968
Personal Author	Koga, T.; Hoff, N. J.
Page Count	142
Abstract	A theoretical investigation of the axisymmetric buckling of complete thin-walled spherical shells under uniform external pressure is undertaken to determine the effect of axisymmetric initial imperfections. In the analysis, the complete spherical shell is divided into two parts; the shallow cap in which the initial imperfection exists, and the remaining portion of the shell most of which deforms in simple contraction. The rotation of the meridian of the cap is assumed in the form of a polynomial function. Four matching conditions are enforced at the juncture of the cap and remainder. The total potential energy of the complete spherical shell is minimized in accordance with the Rayleigh-Ritz approximation method. Two types of initial imperfections are studied; one is an axisymmetric dimple, and the other is a spherical region whose radius of curvature is greater than that of the perfect spherical shell. The maximal values of the pressure parameter rho in the equilibrium state before snap-through were calculated for various values of the geometric parameter lambda, which is proportional to the angular extent of the imperfection for a given radius-to-thickness ratio, and the imperfection amplitude parameter delta, which is the ratio of the initial deviation of the shell mid-surface at the axis of rotation to the wall-thickness. The results of numerical computations show that for all values of delta the lowest buckling pressure is reached when lambda is about 4. (Author)
Keywords	Structural shells Buckling(Mechanics) Spheres Defects(Materials) Approximation(Mathematics) Thickness Polynomials Functions Pressure Geometry Surfaces Pressurization Stresses Potential energy Deformation
NTIS Subject Category	46E - Structural Mechanics 50 - Civil Engineering
Corporate Authors	Stanford Univ Calif Dept Of Aeronautics And Astronautics
Document Type	Technical Report
Title Note	Technical rept.
NTIS Issue Number	196817
Contract Number	N00014-67-A-0112

The Axisymmetric Buckling of Initially Imperfect Complete Spherical Shells.

The Axisymmetric Buckling of Initially Imperfect Complete Spherical Shells.
AD671833

Publication Date	1968
Personal Author	Koga, T.; Hoff, N. J.
Page Count	142
Abstract	A theoretical investigation of the axisymmetric buckling of complete thin-walled spherical shells under uniform external pressure is undertaken to determine the effect of axisymmetric initial imperfections. In the analysis, the complete spherical shell is divided into two parts; the shallow cap in which the initial imperfection exists, and the remaining portion of the shell most of which deforms in simple contraction. The rotation of the meridian of the cap is assumed in the form of a polynomial function. Four matching conditions are enforced at the juncture of the cap and remainder. The total potential energy of the complete spherical shell is minimized in accordance with the Rayleigh-Ritz approximation method. Two types of initial imperfections are studied; one is an axisymmetric dimple, and the other is a spherical region whose radius of curvature is greater than that of the perfect spherical shell. The maximal values of the pressure parameter rho in the equilibrium state before snap-through were calculated for various values of the geometric parameter lambda, which is proportional to the angular extent of the imperfection for a given radius-to-thickness ratio, and the imperfection amplitude parameter delta, which is the ratio of the initial deviation of the shell mid-surface at the axis of rotation to the wall-thickness. The results of numerical computations show that for all values of delta the lowest buckling pressure is reached when lambda is about 4. (Author)
Keywords	Structural shells Buckling(Mechanics) Spheres Defects(Materials) Approximation(Mathematics) Thickness Polynomials Functions Pressure Geometry Surfaces Pressurization Stresses Potential energy Deformation
NTIS Subject Category	46E - Structural Mechanics 50 - Civil Engineering
Corporate Authors	Stanford Univ Calif Dept Of Aeronautics And Astronautics
Document Type	Technical Report
Title Note	Technical rept.
NTIS Issue Number	196817
Contract Number	N00014-67-A-0112