Comparative study on vibro-acoustic properties of sandwich shells containing functionally-graded porous materials in a thermal environment

The dynamics of functionally-graded (FG) sandwich shells with varied pore distributions in thermal environments is investigated, focusing on their free vibration behaviors and sound transmission loss (STL) characteristics. The effective material parameters are calculated by integrating the graded distribution through three distinct pore distribution laws. The dynamic governing equations are derived by means of the first-order shear deformation theory, guided by Hamilton's principle. The solutions for the natural frequency and acoustic transmission loss factor are obtained from the shell's free vibration general solution and the acoustic displacement function, respectively. A detailed numerical analysis is conducted to assess the impacts of the structural and geometric parameters, as well as the ambient temperature, on the vibro-acoustic properties. The results indicate that vibro-acoustic coupling is most significant in shells with a symmetric non-uniform pore distribution, and the resonance frequency shifts towards lower frequencies as the power-law index increases. These findings offer valuable insights for enhancing the design of materials aimed at vibration damping and acoustic management.