Assessment of a global higher-order deformation theory for laminated composite and sandwich plates

Interlaminar stresses and displacements in cross-ply laminated composite and sandwich plates subjected to lateral pressures are analyzed by a global higher-order plate theory which can take into account the effects of both transverse shear and normal stresses. By using the method of power series expansion of continuous displacement components, a set of fundamental governing equations of a two-dimensional global higher-order theory for rectangular laminates subjected to lateral pressures is derived through the principle of virtual work. Several sets of truncated Mth-order approximate theories are applied to solve the static boundary value problems of a simply supported multilayered plate. Transverse shear and normal stresses can be calculated by integrating the three-dimensional equations of equilibrium in the thickness direction satisfying the continuity conditions at the interface between layers and stress boundary conditions at the external surfaces. Numerical results are compared with those of the published three-dimensional layerwise theory in which both in-plane and normal displacements are assumed to be C0 continuous in the continuity conditions at the interface between layers. Effects of the difference of displacement continuity conditions between the three-dimensional layerwise theory and the single-layer (global) higher-order theory are clarified in multilayered composite plates.