Shear buckling of sandwich plates - Incompressible and compressible cores

Shear buckling behavior of sandwich panels with an incompressible and a compressible core is presented. The mathematical formulation includes various formulations for layered sandwich panel such as: Ordinary Sandwich Panel Theory (OSPT), High-Order Sandwich panel Theory (HSAPT) without in-plane core rigidity and with in-plane rigidity (HSAPT-A) Theory. The various models are based on a variational approach that yields the non-linear field equations and the appropriate boundary conditions. The high-order model that takes into account the in-plane rigidity through the depth of the core, denoted as HSAPT-A, uses the accurate solution of the 3D elasticity problem involved. Linearization is achieved using a perturbation technique which yields equations for the pre-buckling and buckling stages along with the appropriate boundary conditions. A Galerkin solution type is adopted for all models and a closed-form solution through the depth of the core is used for the high-order case where the core rigidity is considered. A numerical study of a simply-supported panel with various layouts and dimensions and subjected to in-plane shear load is conducted. The results include bifurcation loads and mode shapes (3D or contour plots) of the displacements, internal stress resultants and interfacial stresses at face-core interfaces.