Synergistic Influence of Auxetic Core Design and RG Foundations on the Buckling Stability of Nanocomposite Sandwich Plates: A Novel MZZT Framework

This study develops a high-fidelity analytical framework to investigate the synergistic effects of auxetic core architecture and Radially Graded (RG) elastic foundations on the buckling behavior of nanocomposite sandwich annular plates. The structure incorporates three-phase nanocomposite face sheets consisting of carbon fibers, an epoxy matrix, and a nano-interphase layer bonded to an auxetic core that enables tailored in-plane deformation and enhanced energy absorption. The governing equations are derived using Murakami’s Zig-Zag Theory (MZZT) combined with the Generalized Differential Quadrature Method (GDQM), which accurately represents layerwise kinematics and interfacial stress continuity while maintaining computational efficiency. The results show that coordinated tuning of the auxetic geometry and foundation gradation produces up to 40% improvement in the critical buckling load compared with plates supported on uniform Winkler foundations. Increasing the rib thickness and inclination angle of the auxetic lattice enhances overall stiffness and stability, while excessive cell elongation reduces buckling resistance due to localized flexibility. Moderate stiffness gradients with β between 0.8 and 1.2 provide the most effective stress–stiffness matching, particularly for radius ratios in the range of 0.5 to 0.7. The proposed framework establishes a new paradigm for adaptive stability control in multifunctional sandwich systems and offers a physically consistent and computationally efficient tool for designing lightweight, highperformance structures in aerospace and energy-related applications.