Probing slow dynamics of consolidated granular multicomposite materials by diffuse acoustic wave spectroscopy
Résumé
The stiffness of a consolidated granular medium experiences a drop immediately after a moderate mechanical solicitation. Then the stiffness rises back toward its initial value following a logarithmic time evolution called slow dynamics. In the literature, \textit{slow dynamics} has been probed by macroscopic quantities averaged over the sample volume, for instance by the resonant frequency of vibrational eigenmodes. This article presents a different approach based on Diffuse Acoustic Wave Spectroscopy (DAWS), a technique that is directly sensitive to the details of the sample structure. The parameters of the dynamics are found to depend on the damage of the medium. Results confirm that \textit{slow dynamics} is, at least in part, due to tiny structural rearrangements at the microscopic scale, such as inter-grain contacts.
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