Role of a fractal shape of the inclusions on acoustic attenuation in a nanocomposite

H. Luo (1) , Y. Ren (2) , A. Gravouil (1) , Valentina M. Giordano (3) , Q. Zhou (2) , H. Wang (2) , Anne Tanguy (1, 4)

1 LaMCoS - Laboratoire de Mécanique des Contacts et des Structures [Villeurbanne]
2 State Key Laboratory of Solidification Processing
3 ENERGIE - (nano)Matériaux pour l'énergie
4 ONERA, Université Paris Saclay [Palaiseau]

Phononic materials structured at the macro- or nano-scale are at the forefront of materials research for controlling transport of sound and heat, respectively. Besides the structure length scale, the exact geometry has been found to be of relevance as well. In this work, we provide an extensive finite element investigation of the effect of the shape of periodically dispersed inclusions in a 2D matrix on propagation and attenuation of an acoustic wave packet. We show that, by significantly complexifying the shape from circular to fractal-like (dendrite shape), phonon scattering at wavelengths comparable with the inner structure of the inclusion is enhanced, leading to a strong attenuation that can be fitted by a compressed exponential function, while in the circular case, the diffusive regime is observed.

Mots clés: Acoustic attenuation; Elastic modulus; Thermal conductivity; Acoustic signal processing; Glass; Phononic crystal; Phonon scattering; Wave mechanics; Thermal transport; Nanocomposites

Domaines: Matériaux; Acoustique [physics.class-ph]

H. Luo, Y. Ren, A. Gravouil, Valentina M. Giordano, Q. Zhou, et al.. Role of a fractal shape of the inclusions on acoustic attenuation in a nanocomposite. APL Materials, 2021, 9 (8), pp.081109. ⟨10.1063/5.0056496⟩. ⟨hal-03323968⟩