Bending behavior of sandwich structures with flexible functionally graded core based on high-order sandwich panel theory

In this study the problem of a sandwich beam with functionally graded (FG) core is attended with use of higher order sandwich panel theory forcing no pre-determined assumptions setting limits to the displacement and stress fields in the core. Face-sheets are analyzed using classical beam theory and the core is subjected to elasticity formulation. Governing equations and boundary conditions are derived using the principle of virtual displacements and governing equations based on five primary variables are solved using Navier’s solution. This method yields nonlinear patterns of displacements in the core and as a result it can manage to present localized effects of the core including the change in the core thickness under the load point which is an improvement on the previous classical and higher order theories. This present theory can handle any type of loadings distributed or concentrated and also any type of boundary conditions even when at the same edge, upper and lower face-sheets do not have the same boundary conditions. The solution is compared with present literature for a beam with conventional core. The results indicate positive effects of using FG core to reduce the possibility of delamination of the structure at interfaces between the upper and lower face-sheets and the core.