Buckling and geometrically nonlinear analysis of sandwich structures

•We present a FEM model for buckling and nonlinear analysis of sandwich panels.•The model is based on a layerwise shell/plate approach.•The results agree well with benchmark solutions.•We conclude that ESL models are not suitable for soft core sandwich panels.

In this work a finite element model is presented for buckling and nonlinear analysis of multilayer sandwich plates and shells, with a soft core sandwiched between stiff elastic layers. The finite element is obtained by assembling all element-layers through the thickness using specific assumptions on the displacement continuity at the interfaces between layers, but allowing for different behaviors of the layers. The stiff elastic layers are modelled using the classic plate theory and the core is modelled using Reddy׳s third order shear deformation theory. The present finite element model is a non-conforming triangular plate/shell element with 24 degrees of freedom for the generalized displacements. This model is applied in the solution of illustrative examples and the results are presented and discussed.