Analysis of critical buckling load in reinforced and unrcinforccd functionally graded double curved shallow shells and cylindrical shells

This study deals with the formulation of governing equations of a generally cross and horizontal grid stiffened functionally graded (FG) plates and shallow shells based upon the classical shell theory and the smeared stiffeners technique taking into account geometrical nonlinearity in Von Karman-Donnell sense. The material properties of the FG plates are assumed to be temperature- independent and vary continuously through the thickness according to a simple power law distribution in terms of the volume fractionof constituents. By use of the Galerkin method an approximated analytical solution to the nonlinear stability problem of reinforced FGM plates and shallow shells is performed. The postbuckling load-deflection curves of the shells are investigated and analytical expressions of the upper and lower buckling loads are presented. There are different comparison between effect of stiffeners and type of them and investigated structure.