Sound insulation analysis of micro-perforated panel coupled with honeycomb panel considering air cavity for offshore plants

Abstract

The wall panels used in offshore plants require sound insulation performance as well as fireproofing. A honeycomb panel made of metal is incombustible but unsatisfactory at the middle frequencies for sound transmission loss because the coincidence frequency occurs when the bending wavelength on the panel matches the wavelength of the incident wave. In this study, the application of a micro-perforated plate to the honeycomb panel was considered to supplement the sound transmission loss at the middle frequencies. The honeycomb core was assumed to overlap an orthotropic layer with an air layer, and face sheets were assumed to be isotropic. The kinetic and potential energy for the face sheets and the honeycomb core, the kinetic energy for the air layer located between the face sheets, and the sound absorption coefficient for the panel were derived. These were substituted into the Lagrange equation, and by solving the equation, the sound transmission loss was obtained. By comparing the experimental results with theoretically predicted results, it was found that the theory well reflected the measured surface density, elasticity, and absorption coefficient. Finally, simulations were performed for the micro-perforated plate perforation presence, micro-perforated plate perforation diameter, cell wall thickness, and cell size. These were analyzed with regard to the surface density, elasticity, and absorption coefficient.