Acoustic wave propagation in functionally graded viscoelastic honeycomb sandwich shells: A comprehensive analysis of sound transmission loss

This study investigates the acoustic wave propagation characteristics and sound transmission loss (STL) of functionally graded viscoelastic (FGV) honeycomb sandwich cylindrical shells through a rigorous mathematical and mechanical framework. By integrating the modified Gibson’s formula for the honeycomb core and frequency-dependent viscoelastic properties of FGV materials, a comprehensive analytical model is developed using Hamilton’s principle and first-order shear deformation theory. The governing equations account for structural-acoustic coupling, external airflow effects, and geometric/material parameter variations, including shell radius, core thickness, hexagonal cell dimensions, and FGV foam gradient indices. Numerical solutions reveal that the STL is highly sensitive to structural stiffness and mass distribution: increasing the core thickness enhances STL across all frequency regimes, while larger radii reduce stiffness-controlled region performance. The viscoelastic damping and gradient index of FGV foam layers significantly influence low-frequency STL, whereas external flow Mach numbers shift critical frequencies in the mass-controlled region. Notably, resonance frequencies remain invariant to aerodynamic conditions, emphasizing the dominance of intrinsic structural parameters. This work bridges advanced composite mechanics with vibroacoustic performance optimization, providing theoretical insights for designing lightweight, high-damping sandwich structures in aerospace and transportation applications. The findings highlight the potential of FGV materials and honeycomb sandwich structures for noise control applications and the synergy between mathematical modeling and material engineering.