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Propriétés élastiques et viscoélastiques de matériaux composites adaptatifs

Abstract : Magnetorheological elastomers are smart composite materials, whose properties can be
controlled by a magnetic field. They are made of magnetic particles, structured in unidirectional chains
inside a silicone elastomer. Under field, the tests have revealed a high increase of the mechanical
properties: up to 35kPa for a modulus of 62kPa in quasistatic tension, and in dynamic solicitation a
raise of E' of 600kPa at ε=1%, which can even reach 21MPa at ε=10-5! In this latest situation, the
structuring of the particles in chains also results in a sharp increase of Payne effect and the energy
dissipation, much more pronounced under field, even a tiny one (15kA/m). We assume that the bonds
between the polymer and the particles progressively break due to the high local stresses between two
particles (in quasi-contact). To ease the study, a chemical treatment of the surface of the particles has
been set up thanks to functional molecules. The modelling has firstly been built on a macroscopic
system (where all the parameters are controlled), and validated by finite elements simulations (FEM).
An effective medium method can predict the behaviour of a composite with grafted particles (before
debonding), whereas a semi-analytical approach, using a Griffith debonding criteria predicts the
viscoelastic behaviour of the MR elastomer. The complexity of the microstructure and its evolution
have been evaluated, under field, by quasi-static cycles (leading to a σ of -40kPa at ε=0) and
magnetostriction measurements. Other properties can be obtained, such as: piezzoresistivity, periodic
stripes (magnetic guides)...
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https://tel.archives-ouvertes.fr/tel-00009415
Contributor : Eric Coquelle <>
Submitted on : Wednesday, June 8, 2005 - 4:07:00 PM
Last modification on : Monday, October 12, 2020 - 10:27:38 AM
Long-term archiving on: : Friday, April 2, 2010 - 9:36:44 PM

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Eric Coquelle. Propriétés élastiques et viscoélastiques de matériaux composites adaptatifs. Mécanique [physics.med-ph]. Université Nice Sophia Antipolis, 2004. Français. ⟨tel-00009415⟩

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