4. Post-Buckling

Sandwich structures are capable of sustaining loading beyond the buckling bifurcation point. With this in mind, a comprehensive geometrically nonlinear theoretical treatment of sandwich plates and shells is considered to provide insight into their structural performance within this loading region. Within this comprehensive theoretical treatment, there are few structural and material conditions considered. The face sheets are considered symmetric with respect to their local and global mid-surfaces while constructed from anisotropic laminated composites. The facings are assumed imperfect and thin thereby neglecting the transverse shear stresses in the facings. The core is assumed to be of the weak-type construction. With these theoretical aspects, two cases of laminated facings are considered, cross-ply and angle-ply. Two formulations, the mixed formulation and the displacement formulation, are presented within the theoretical developments. To arrive at the post-buckling solution, the extended Galerkin method and Newton’s method are adopted. Finally, a number of kinematical and physical parameters are considered in regard to the load-carrying capacity of these sandwich panels. Several results are presented which provides sufficient insight to the behavior of these structures.