Unified Theory for the Bending and Buckling of Sandwich Shells Application to Axially Compressed, Circular Cylinder Shells
Final technical rept.
STANFORD UNIV CA DEPT OF AERONAUTICS AND ASTRONAUTICS
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A variational development of the governing equations and boundary conditions for the bending and buckling of sandwich curved plates and shells is presented. The theory is applicable to sandwich construction of the honeycomb type and may be used to describe bending, buckling, and postbuckling behavior. With the coupled effects of core transverse shear and normal strain included, the theory reflects the presence of 8 degrees of freedom and 2 constraining conditions. Nine boundary conditions per curved plate or shell edge can be specified apart from the four of the usual type for each of the sandwich facing elements, in terms of either a generalized force or displacement, a condition for either the shear loading or the average displacement of the core is obtained. The governing equations, specialized for small-displacement buckling, are applied to the case of axial compression of circular cylindrical shells. The unified theory analysis reflects three modes of buckling classical general instability and both symmetric and antisymmetric wrinkling.