Acoustic Properties Of Auxetic Foams
Author(s)
I. Chekkal, C. Remillat & F. Scarpa
Abstract
Auxetic foams have raised some interest in noise and vibration control
applications as they showed unusual acoustic properties compared to
conventional ones, particularly at low frequencies. Auxetic foams are porous
materials with a negative Poisson’s ratio. They expand in all directions when
only pulled in one. In this paper, the acoustic properties of auxetic foams are
described both from a numerical and experimental point of view. The acoustic
absorption properties of both auxetic and conventional foam samples were
measured using a two-microphone impedance tube to provide a comparison
between the two types of cellular solids. The acoustical properties of auxetic
foams are discussed in terms of the dynamic parameters. A numerical model
based on Biot’s theory is derived in which the dynamic coefficients of foams are
evaluated. Results are compared and commented to provide explanations on the
unusual acoustical behaviour of auxetic foams.
Keywords: auxetic foams, dynamic parameters, acoustic properties, porous
media, Biot’s model.
1 Introduction
Porous materials are commonly used in vibration and noise control applications
as they are known for their ability to dissipate acoustic waves propagating in
their medium. A porous material consists of a solid phase which is the frame or
the skeleton and a fluid phase which is the air or the fluid in pores. Auxetic
foams are a subset of porous materials. They can be produced from conventional
low density open cell polymer foams by causing the ribs of each cell to
permanently protrude inward, resulting in a re-entrant structure. Auxetic foams
are characterised by a negative Poisson’s ratio. They expand in all directions
when only pulled in one. Such unusual behaviour raised some interest in the
modern word due to their unconventional mechanical and acoustic properties.
Keywords
auxetic foams, dynamic parameters, acoustic properties, porous
media, Biot’s model.
Related Book
Other papers in this volume
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