A Consistent Shear Deformable Theory for Laminated Plates

Abstract : A consistent theory for the interlayer coupling of transverse shear in laminated plates is presented. Starting from a generalization of Reissner's variational principle for elastic orthotropic plates to laminated plates, it is shown that the shear force in any lamina may depend upon the shear deformation of that lamina as well as others. The coupling depends on the material properties, the stacking sequence and the applied surface tractions. Several existing theories of homogeneous as well as laminated plates are seen to arise as specializations/approximations of the general theory. The nature of the constitutive coupling is illustrated by studying a 12-layer graphite-epoxy laminate. The theory is implemented in a finite element computer program and applied to the determination of stresses in cross-ply as well as angle-ply free- edge delamination specimens, and to study the frequencies of vibration of laminated plates. Composite Laminates, Finite Element Method, Delamination, Free-edge Delamination, Discrete Plate Theory.