Gradient Wall‐Thickness Design of Fluorite‐Type Plate Lattice Metamaterials for Integrated Mechanical–Acoustic Performance

Lightweight design combined with multifunctional performance has recently garnered significant interest in the development of advanced metamaterials. This study systematically investigates a fluorite‐type plate lattice metamaterial with adjustable porosity, using numerical simulations and quasistatic compression experiments to evaluate how various geometric parameters affect its mechanical and acoustic properties. Uniform structures display three characteristic collapse modes: uniform collapse, interlayer shear, and local buckling. The results indicate that increasing wall thickness and layer count improves load‐bearing capacity, while optimizing pore size and cell width achieves a balance between strength, specific energy absorption, and low‐ to mid‐frequency sound insulation. Based on this multiparameter analysis, gradient wall‐thickness configurations are introduced, where thinner layers deform initially while thicker layers provide delayed reinforcement, enhancing deformation stability and promoting uniform energy absorption. Among these gradient designs, H‐L‐H structure configuration increases densification strain by roughly 1.87% and provides the highest high‐frequency sound insulation, up to 8.71 dB. In contrast, L‐H‐L structure configuration achieves nearly perfect sound absorption within 4–4.5 kHz frequency range. Overall, this strategy enables the synergistic optimization of mechanical and acoustic performance through combined multiparameter tuning and gradient wall‐thickness design, offering a promising approach for lightweight multifunctional metamaterials in aerospace, transportation, and noise‐sensitive engineering applications.