Strong sampling surfaces formulation for layered shells

The strong SaS formulation for the three-dimensional (3D) stress analysis of layered shells is based on a new concept of SaS located at Chebyshev polynomial nodes throughout the layers and integration of the equilibrium equations of elasticity. The idea of the SaS method consists in choosing the arbitrary number of SaS parallel to the middle surface in order to introduce the displacements of these surfaces as basic shell unknowns. Such choice of unknowns with the use of the Lagrange polynomials in assumed approximations of displacements and strains through the layer thicknesses leads to a compact form of the layered shell formulation. The feature of the proposed approach is that all SaS are located inside the layers at Chebyshev polynomial nodes. The use of interfaces is avoided that makes possible to minimize uniformly the error due to the Lagrange interpolation. Therefore, the strong SaS formulation can be applied efficiently to the 3D analysis of layered composite shells.