An alternative determination of transverse shear stiffnesses for sandwich and laminated plates

Two-dimensional shear-deformable laminated plate theories can be classified as equivalent single-layer theories and layerwise theories. Layerwise theories lead to better approximations than equivalent single-layer theories, but the large number of independent unknowns in these theories requires more computational power in comparison with calculations, based on equivalent single-layer theories. The quality of any equivalent single-layer theory based calculation is influenced by the correct determination of the effective stiffnesses. Many theories result in identical stiffnesses for bending, tension/compression, in-plane shear and torsion. The differences between the approaches are connected with the transverse shear stiffnesses. The method of determination of the transverse shear stiffnesses proposed here leads to expressions which depend on the solution of a Sturm-Liouville-problem. For special cases, the stiffnesses are calculated and compared with results from other authors. It can be shown that the present approach can be useful not only in the case of laminated plates, but also for sandwich plates. (C) 2000 Elsevier Science Ltd. All rights reserved.