
Accession Number : AD0671833
Title : THE AXISYMMETRIC BUCKLING OF INITIALLY IMPERFECT COMPLETE SPHERICAL SHELLS.
Descriptive Note : Technical rept.,
Corporate Author : STANFORD UNIV CALIF DEPT OF AERONAUTICS AND ASTRONAUTICS
Personal Author(s) : Koga,Tatsuzo ; Hoff,Nicholas J.
Report Date : MAY 1968
Pagination or Media Count : 142
Abstract : A theoretical investigation of the axisymmetric buckling of complete thinwalled 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 RayleighRitz 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 snapthrough were calculated for various values of the geometric parameter lambda, which is proportional to the angular extent of the imperfection for a given radiustothickness ratio, and the imperfection amplitude parameter delta, which is the ratio of the initial deviation of the shell midsurface at the axis of rotation to the wallthickness. The results of numerical computations show that for all values of delta the lowest buckling pressure is reached when lambda is about 4. (Author)
Descriptors : (*SHELLS(STRUCTURAL FORMS), BUCKLING), SPHERES, DEFECTS(MATERIALS), APPROXIMATION(MATHEMATICS), THICKNESS, POLYNOMIALS, FUNCTIONS(MATHEMATICS), PRESSURE, GEOMETRY, SURFACES, PRESSURIZATION, STRESSES, POTENTIAL ENERGY, DEFORMATION
Subject Categories : Structural Engineering and Building Technology
Mechanics
Distribution Statement : APPROVED FOR PUBLIC RELEASE