INTERACTION BETWEEN AXISYMETRIC AND MULTILOBED CREEP BUCKLING OF CIRCULAR CYLINDRICAL SHELLS IN AXIAL COMPRESSION

The present theoretical investigation studies the effect of small multilobed initial deviations from the exact shape upon the deformations and the critical time of a thin-walled circular cylindrical shell which was manufactured with initial axisymmetric deformations. To facilitate the analytical work, the actual solid wall of the shell is imagined to be replaced by an equivalent sandwich wall. The general equilibrium equations derived for shallow shells are expressed in terms of stresses and deviations corresponding to the equivalent sandwich model. The radial displacement as well as the meridional, circumferential and membrane shear stresses are expressed by finite Fourier series for each face of the sandwich model. The compatability conditions used in conjunction with the equilibrium equations lead to a system of linear and nonlinear equations. It is assumed that all deformations are due to nonlinear steady creep governed by Odqvist's power law. The solution of this system of equations is carried out by introducing the solution obtained from the axisymmetric creep buckling theory developed by N.J. Hoff. Furthermore, in order to simplify the equations, it is assumed that the deformations remain small compared to the shell thickness. A closed form solution is found for the multilobed deformation rates and for the critical time as well. However, the latter is too complicated to be evaluated by hand. A numerical integration of the deformation rates shows, for a given cylinder, that the multilobed creep buckling deformations grow much faster than the axisymmetric. Indeed, we find that Koiter's theory of bifurcation buckling for perfectly elastic axially compared circular cylindrical shells has its counterpart in creep buckling.

• Corporate Authors:

  Stanford University

  Department of Aeronautics and Astronautics
  Stanford, CA  United States  94305
• Authors:
  • Benoit, M
• Publication Date: 1973-8

Media Info

• Features: Appendices; References;
• Pagination: 111 p.

Subject/Index Terms

• TRT Terms: Axial loads; Buckling; Creep; Cylinders (Geometry); Shells (Structural forms)
• Uncontrolled Terms: Axial loading; Cylindrical shells
• Subject Areas: Marine Transportation; Materials;

Filing Info

• Accession Number: 00050705
• Record Type: Publication
• Source Agency: Ship Structure Committee
• Report/Paper Numbers: Tech Rpt #26 PhD Thesis
• Contract Numbers: N00014-67A-0112-003
• Files: TRIS
• Created Date: Jan 24 1974 12:00AM