Comportement mécanique et vibroacoustique des matériaux cellulaires.

Abstract

Cellular materials constitute a privileged class of composite materials due to the specificity that their physical properties depend both on their constituent material and on the spatial arrangement of this material within a millimetric scale architecture such that metal foams and honeycombs. Auxetic materials, more particularly, have in addition a negative Poisson's ratio. All these properties vary a lot depending on the architecture of the considered cellular materials, i.e. the morphology. The unit cell forming the network has a symmetry with respect to the axes and ; each member consists of two small horizontal links of length h, a large link of length H and a link of length , forming an angle θ with the direction of the straight links. The numerical simulations carried out showed a strong dependence between the geometrical parameters of the cell and the mechanical properties of the cellular solid. Dependence confirmed by experimental results. The vibro-acoustic study of the structure made it possible to determine the absorption and transmission loss coefficients by the structure of the cellular material. The periodic character, and in both directions and , made it possible to simplify the problem to one dimension and by using the conditions of Floquet-Bloch the problem was reduced to the study of a single cell-unit. We have also explored the influence of the angle of incidence of the propagation wave on the reflection, absorption and transmission coefficients and by the same has shown the criticality of the angle θ = 50 ° , angle that allows zero transmission, maximum reflection and absorption.