Buckling Analysis of Composite Sandwich Panel with Symmetric FGM Core,Using Improved High-order Theory

In this paper, linear elastic buckling analysis of rectangular composite sandwich panel with composite laminate faces and symmetric functionally graded material (FGM) core is presented. Unidirectional steady in-plane forces and simply supported boundary conditions are applied on the faces’ edges only. Hamilton principle and functional method are used to derive equilibrium equations, which are usually minimum functional of stored energy. In the mathematical formulation a new improved higher-order sandwich panel theory (IHSAPT) was used. First shear deformation theory (FSDT) is used for faces. Core displacement in various directions is modeled by polynomial function with indeterminate coefficients. It is assumed that the core is able to sustain shear and normal in-plane stresses. Temperature and humidity effects are neglected and the FGM core is modeled symmetrically. Finally, the effects of aspect ratio, thickness to side ratio, core materials’ modulus ratio, and various kinds of FGM distribution functions and powers on the critical buckling load are investigated. The numerical results show, that the effects of in plane stresses in the thick functionally graded cores on the critical buckling load cannot neglected. Also, the effects of type of FGM distribution functions and powers on the critical buckling load are considerable.