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Études des propriétés mécaniques d'empilements désordonnés de billes de gel

Abstract : The presentation of a new experimental apparatus to measure directly the osmotic pressure in gels is done. Experiences performed on cylindrical poly(acrylic acid) gels show that the osmotic pressure varies linearly with the concentration of counter-ions below the condensation threshold. The behaviour of disordered loose packings of spheres of gel swollen at constant salinity and submitted to an oedometric compression is non-linear. The force-deformation characteristic presents three regimes which can be described by a power law: the consolidation regime is governed by an exponent close to the Hertz exponent: m1 = 1.6. In the consolidated regime, the number of contacts increases with the deformation; the exponent m2 which describes the behaviour is then greater than m1 : m2 = 2.5. Finally, for large deformations, a strongly non-linear behaviour appears where all the contacts between particles are established and where the behaviour is dominated by die contribution of the particles which are greatly deformed : m3 = 3.5. The hysteresis present in the system is mainly due to the viscous dissipation in the particles without expulsion of the solvent. Considering the isotropic compression induced in the packing of spheres by varying the salinity of the solution, the behaviour of the packing is again non-linear with the free parameter (salinity). The observed behaviour is the consolidate one and is governed by an exponent greater than that governs the behaviour of the packing in the same regime when it is submitted to an oedometric compression.
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  • HAL Id : tel-00529715, version 1

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Touria Lachhab. Études des propriétés mécaniques d'empilements désordonnés de billes de gel. Mécanique [physics.med-ph]. Ecole Nationale des Ponts et Chaussées, 1994. Français. ⟨tel-00529715⟩

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