Mechanical characterisation of acoustic foams: fractional derivatives approach
Invited paper
Laboratoire d'Acoustique de l'Université du Maine, UMR CNRS 6613
Tuesday 2 june, 2015, 16:20 - 16:40
0.7 Lisbon (47)
Abstract:
Porous materials like polymer foam and glass wool are widely used for noise
control in several engineering activities such as aeronautics and automotive
industries. Their properties are two-fold: sound absorption and damping of the
nearby structure.
Generalized constitutive relationships of viscoelastic foams are investigated
in which the time derivatives of integer order are replaced by derivatives of
fractional order. To this point, the justification of such models has resided
in the fact that they are effective in describing the behavior of real
materials. In this work, the three-parameter fractional Kelvin Voigt model is
compared to the four-parameter fractional Zener model in frequency domain and
applied to the prediction of the relaxation function in time domain. These
three-parameter and four-parameter models are theoretically analyzed in time
domain. The fitted storage and loss moduli over wide range of frequency, up
to 10 kHz, can be used in the Biot poroelasticity theory to predict the sound
absorption coefficient of the foam.