A direct homogenisation approach for determination of the stiffness matrix for microheterogeneous plates with application to sandwich panels

The present study is concerned with the numerical determination of the effective plate stiffness matrix for composite shells with microheterogeneous layers. Contrary to the standard two-step procedure, where the effective plate or shell stiffness matrix is derived by a projection of the effective elasticity tensor onto the plate or shell reference surface, a direct method is proposed. This method uses a strain energy based RVE-procedure which assumes mechanical equivalence of a representative volume element for the given microstructure and a corresponding plate element if the strain energy in both elements is equal, provided that the effective deformation is equal in an average sense. In parametric studies concerning sandwich plates with hexagonal honeycomb cores, it is observed that the direct method and the two-step procedure are equivalent for the determination of the in-plane and the transverse shear properties while a significant deviation of the results obtained by both methods is found in case of the effective bending properties. (C) 2003 Elsevier Ltd. All rights reserved.