OPTIMIZATION OF ACOUSTIC ABSORBERS WITH MICROSTRUC- TURE: A MULTISCALE STUDY Nikolai Gorbushin, Naili Salah, Nguyen Vu-Hieu Université Paris-Est Créteil, La boratoire Modlélisation et Simulation Multi Echelle, MSME 8208 CNRS, France email: vu-hieu.nguyen@u-pec.fr Poroelastic materials are well known to possess exclusive properties for sound absorption. How- ever, tuning their properties for achieving the better acoustic performance is not an easy experimental tasks which can be significantly improved by mathematical modelling. In this work we exploit the homogenization procedure to determine the effective properties of an air-saturated material with mi- crostructure. These properties are then used to solve an acoustic problem with the final objective of finding the optimal design microstructural parameters for the highest acoustic absorption. The mi- crostructure of a material is formed by the translation of a unit cell. We study certain topologies of a unit cell to verify their effects on the optimization results. Moreover, we consider different types of a skeleton material (perfectly rigid, stiff and soft frames) and demonstrate the influence of the material properties on the optimal design parameters. Particularly, the effective elastic properties experience different patterns for the stiff and soft matrix materials. It leads to the distinct behavior of the absorp- tion coefficient. Additionally, the optimal design parameters for a poroelastic material with a stiff and rigid frames become identical with the high values of optimal porosity whereas for a material with soft frame the optimal porosity remains low. The developed procedure can be adopted for the studies of related problems, such as optimal acoustic absorption of sandwich panels. Keywords: Poroelasticity, homogenisation, effective properties, acoustic absorption, optimisation 1. Introduction The production of new materials requires prior knowledge of the content of components, their me- chanical characteristics, geometrical parameters of compounds and their arrangement inside a solid. Among the huge class of various materials, we focus on poroelastic materials which are widely used as acoustic absorbers and thermal insulators due to their exclusive properties [1]. In the context of design of poroelastic panels with acoustic absorption and/or transmission loss features, optimal macroscopic acous- tic properties of the panel depend not only on the characteristics of bulk porous materials but also on the structural parameters such as the panel’s thickness. Moreover, the composite panel made of mixture of different poroelastic materials may have improved acoustic performances in absorption or transmission loss [2]. The goal of this work is to formulate and implement a procedure to design a poroelastic panel with a maximum acoustic absorption and optimal microstructural cell parameters found by means of the homogenisation technique. 1