An analytical study of sound transmission through stiffened double laminated composite sandwich plates

The main objective of this research work is focused on sound transmission loss analysis of stiffened double laminated composite sandwich plate structures subjected to plane sound wave excitation, wherein the laminated composite plates are composed of perfectly bonded functionally graded carbon nanotubes (CNTs) reinforced composite layers, and in each layer, the carbon nanotubes is uniform or functionally graded along with the thickness direction of structures, and three types of the CNTs distributions are studied. The extended rule of mixture is employed to determine the properties of the composite material. The compatibility of displacements on the interface between the plate and the stiffeners is employed to derive the governing equation of each stiffener. Then fluid-structure coupling is considered by imposing velocity continuity condition at fluid-structure interfaces. By using the space harmonic approach and virtual work principle, the sound transmission loss is described analytically. Since no existing results of sound insulation can be found for such composite material plate structure, comparison studies can only be made with the isotropic and laminated case. Good agreement is found from these comparison studies. Based on the developed theoretical mode, the influences of the volume fractions of CNTs, distribution type of CNTs, structural damping, lamination angle and the number of layers on sound transmission loss are subsequently presented. (C) 2018 Elsevier Masson SAS. All rights reserved.