Forooghi, Darya2025-11-072025-11-072025-09-102025-11-07http://hdl.handle.net/1993/39447Laminate plate and shell structures with symmetric cross-ply configurations are widely used due to their high stiffness-to-weight ratio. However, conventional lamination theo-ries rely on simplifying assumptions that may introduce inaccuracies, and experimental data is often limited and expensive to obtain. Therefore, having a reliable and accurate numerical model as a reference is valuable for evaluating and improving the analytical approach. This study evaluates the predictive capability of lamination theories by integrating multiple micromechanics models with First-Order Shear Deformation Theory (FSDT), and comparing the results against voxel-based finite element modeling (VB-FEM), which serves as a high-fidelity numerical reference. A range of models—including Voigt–Reuss, Chamis, Halpin–Tsai and its modified form, Generalized Self-Consistent, Mori–Tanaka, Bridging, and two iterative isotropized formulations—are assessed for unidirectional laminae. The most accurate micromechanics models are then used in combination with FSDT to assess the stiffness predictions for cross-ply laminates. Pre-dictions are evaluated across a wide range of fiber volume fractions, from approximate-ly 10% to 70%. Comparison reveals that while all models predict the longitudinal modulus accurate-ly, significant deviations arise in predicting transverse and shear properties. The Bridg-ing model consistently yields the closest agreement with VB-FEM across all five elastic constants, maintaining accuracy even at high volume fractions where the modified Hal-pin–Tsai model begins to fail. Discrepancies in micromechanics-based lamina properties propagate to laminate-level stiffness predictions, highlighting the critical role of model selection. These findings establish VB-FEM as a valuable tool for validating analytical models and guide improved modeling strategies for laminated composite design.engUnidirectional LaminaVoxel-based finite element methodCross-ply laminate stiffnessMicromechanics models