Singular stress fields in cellular cores for structural sandwich panels

The present study is concerned with the singularity of the stress fields in the cell walls of hexagonal honeycomb cores used in sandwich construction. The stress singularity under consideration occurs at the intersections of the cell walls at the core face sheet interface due to incompatibilities in the modes of deformation associated with the unconstrained cellular core and the face sheets. The stress fields are investigated by means of a closed-form asymptotic analysis and numerically by means of the finite element method. The stress singularity at the intersection is found to be of the pure power-law type. The dependence of order and intensity of the singularity on core and face sheet geometry and material as well as on the loading conditions is investigated in detail. A brief discussion of possible fracture concepts closes the study.