Buckling and postbuckling of delaminated composite sandwich beams

Consider a sandwich plate with balanced or unbalanced anisotropic composite laminated faces and an ideally orthotropic honeycomb core. The paper presents elastic buckling and postbuckling analysis of an axially loaded plate with an across-the-width delamination symmetrically located at the interface of the upper face and core. Since the plate undergoes cylindrical bending deformations on the postbuckling states for the cases considered, only one-dimensional formulations are employed. The transverse deflection and bending moment of the postbuckling solutions are obtained by applying the one-dimensional formulations. The explicit closed-form expressions of the critical buckling load and energy release rate are derived based on this postbuckling solution. Because there is no such general solution presented in the literature, verification is done by some special cases such as delaminated composites (without core), perfect sandwiches (without delamination), and thin-film delaminations. The effects of core, face, and delamination length on the buckling load, the delamination growth, and the ultimate axial load capacity of the delaminated composite sandwiches are also discussed in this paper.