Acoustic transmission modeling of smart multifunctional graded porous shells under subsonic flow and hygrothermal conditions

Due to the increasing need for lightweight and adaptable structures in fields such as aerospace, automotive, and noise mitigation, a comprehensive understanding of the vibroacoustic characteristics of advanced multifunctional smart shell systems under realistic operating environments is crucially important. A significant contribution of this work lies in analyzing the sound transmission loss (STL) of single- and double-walled functionally graded porous magneto-electro-elastic (FGPMEE) shells, considering the combined effects of porosity, applied electric voltage, magnetic potential, Mach number, temperature, and humidity variations. The power law model characterizes the material's graded characteristics, which change with thickness from barium titanate (BaTiO₃) to cobalt iron oxide (CoFe₂O₄). Furthermore, four separate distributions of porosity for the smart materials are taken into account. The dynamic-acoustic equations are obtained by using third-order shear deformation theory (TSDT) and Hamilton's principle, along with fluid-structure boundary conditions. The semi-discretization and state-space representation of the governing equations are achieved by the use of Fourier series expansions. Following the results' validation, a thorough parametric analysis is conducted to assess the effects on transmission loss performance across a defined frequency range of the following variables: applied electric voltage, magnetic potential, Mach number, temperature changes, humidity levels, and incidence angle. These findings demonstrate the potential of FGPMEE shells for enhanced noise mitigation under diverse operational scenarios.