Abstract

The aim of the present work concerns the influence of the interface quality, porosity and temperature on the acoustic coefficient behaviour of multilayer structures. A plane periodic multilayer structure composed of two plates in contact with different interface qualities is used: one in Aluminium (AL) and the other one in Polyethylene (PE). These isotropic materials, present a high acoustic impedance contrast. To obtain the effective acoustic parameters of the perforated polyethylene layer, the Hashin-Shtrikman (HS-ort) model is used. Pseudo Stroh-Formalism (PSF) is used to calculate the reflection and transmission coefficients. Then, the absorption coefficient and sound transmission loss are deduced. To model the interface conditions, mass-spring systems that represent particle bonds at the microscopic level are used. Results showed that the parameters of interface and temperature strongly influence the absorption and the sound transmission loss. The more the stiffness of the spring increases, the amplitude of the sound transmission loss decreases and a shift towards lower frequencies is observed on absorption according to two insonification sides. The temperature variation inside the multilayer structure allows us to characterize the system with local effective parameters. Application to local materials made of Stabilized Earth Bricks (SEB) and Compressed Earth Bricks (CEB) is also presented.

Keywords:Absorption; Sound transmission loss; Thermoelastic multilayer; Porosity; Interface; Stabilized, Compressed earth