Soft porous silicone rubbers with ultra-low sound speeds in acoustic metamaterials

Abdoulaye Ba (1) , Artem Kovalenko (2) , Christophe Aristégui (1) , Olivier Mondain-Monval (2) , Thomas Brunet (1)

1 I2M - Institut de Mécanique et d'Ingénierie de Bordeaux
2 CRPP - Centre de Recherche Paul Pascal

Soft porous silicone rubbers are demonstrated to exhibit extremely low sound speeds of tens of m/s for these dense materials, even for low porosities of the order of a few percent. Our ultrasonic experiments show a sudden drop of the longitudinal sound speed with the porosity, while the transverse sound speed remains constant. For such porous elastomeric materials, we propose simple analytical expressions for these two sound speeds, derived in the framework of Kuster and Toksöz, revealing an excellent agreement between the theoretical predictions and the experimental results for both longitudinal and shear waves. Acoustic attenuation measurements also complete the characterization of these soft porous materials.

Domaines: Physique [physics]

Abdoulaye Ba, Artem Kovalenko, Christophe Aristégui, Olivier Mondain-Monval, Thomas Brunet. Soft porous silicone rubbers with ultra-low sound speeds in acoustic metamaterials. Scientific Reports, 2017, 7 (1), pp.1-6. ⟨10.1038/srep40106⟩. ⟨hal-02901486⟩