Abstract: In this paper, in-plane equivalent elastic modulus of a honeycomb sandwich, consisting of hexagonal cell core and face sheet, is studied by using a theoretical analysis. It is shown that the equivalent elastic modulus can not been analyzed with high precision by treating the honeycomb as a composite of two materials: the core and the face sheet, because the core consists of portions of the slanting cell walls and the vertical cell walls, whose rigidities differ greatly. Dividing the core into the slanting cell wall portion and the vertical cell wall portion, and regarding the honeycomb as a composite of three materials, a method to calculate elastic modulus is proposed based on the principle of the minimum potential energy, and its validity is verified by numerical results of FEM.

Key words: FEM