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Etude des milieux granulaires secs et mouillés à l'aide des ondes ultrasonores

Abstract : This work deals with the sound propagation in a stressed dense granular medium. Elastic
waves offer a non invasive method for probing the structure, the viscoelastic properties and non linear
behaviours of force networks in the material. First of all, we briefly describe some results about
small-amplitude ultrasound propagation in granular materials (effective coherent modes, multiply
scattered waves). After then, we show how to infer elastic modulii and characterize the internal
dissipation by using coherent waves and multiply scattered waves, respectively. By studying the
influence of small amount of added liquid in the medium (< 0,1%) or the surface state of beads,
on the viscoelastic properties of dry and wet granular media, we are able to identify two different
origins of dissipation : frictionnal and viscous mechanisms. Finally, we study the non linear behaviour
of large-amplitude sound propagation in a granular medium. More precisely, we characterize
experimentally the reversible hertzian non linear elasticity of the granular medium via harmonic
generation. And then we discuss an original experimental finding which concerns irreversible interaction
process between elastic waves and granular medium. The underlying physics is related to the
Mindlin hysteretic non linearity which causes a softening of the elastic modulus of granular medium
accompagnied by micro-rearrangements at the grain asperity scale.
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https://tel.archives-ouvertes.fr/tel-00129738
Contributor : Thomas Brunet <>
Submitted on : Monday, July 23, 2007 - 3:01:55 PM
Last modification on : Wednesday, February 26, 2020 - 7:06:03 PM
Long-term archiving on: : Tuesday, September 21, 2010 - 1:41:21 PM

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  • HAL Id : tel-00129738, version 2

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Thomas Brunet. Etude des milieux granulaires secs et mouillés à l'aide des ondes ultrasonores. Acoustique [physics.class-ph]. Université de Marne la Vallée, 2006. Français. ⟨tel-00129738v2⟩

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