Cylindrical bending of unsymmetric laminated composite and sandwich plates

The present study introduces a novel higher-order zigzag theory for the analysis of laminated composite and sandwich plates under cylindrical bending. The formulation employs a higher-order description of in-plane displacements to capture zigzag variation through the thickness, enabling improved prediction of both global and local responses while retaining the same number of unknowns as the First-Order Shear Deformation Theory (FSDT). The applicability of the model is demonstrated for a wide range of laminated and sandwich configurations, including symmetric, antisymmetric, cross-ply, angle-ply, unsymmetric laminates, and antisymmetric sandwich plates, with variations in thickness ratios, stacking sequences, and number of layers. The proposed theory provides an improved representation of transverse shear behavior by ensuring continuity of transverse shear stresses directly from constitutive relations. In addition, transverse shear stresses are evaluated through integration of the equilibrium equations to further enhance prediction accuracy. The results are assessed through systematic comparisons with selected existing plate theories and available three-dimensional elasticity solutions. Several established models from the literature are independently reproduced and implemented in Matlab, and their results are presented in both tabular and graphical forms to provide a consistent and meaningful evaluation of the predictive capability of the present formulation.