Thursday, November 21, 2013
Mechanical and Civil Engineering Seminar
Micro-Deformation Mechanisms of Particle-Filled Magnetorheological Elastomers: Experiments, Theory and Numerics
Kostas Danas, Research Assistant Professor, Laboratoire de Mécanique des Solides, LMS, Ecole Polytechnique
Magnetorheological elastomers (MREs) are ferromagnetic particle impregnated rubbers whose mechanical properties are altered by the application of external magnetic fields. Due to their coupled magnetoelastic response, MREs are finding an increasing number of engineering applications. In this work, we present a combined experimental, theoretical and numerical study of the macroscopic response of a particular MRE consisting of a rubber matrix phase with spherical carbonyl iron particles. The MRE specimens used in this work are cured in the presence of strong magnetic fields leading to the formation of particle chain structures and thus to an overall transversely isotropic composite. The MRE samples are tested experimentally under uniaxial stresses as well as under simple shear in the absence or in the presence of magnetic fields and for different initial orientations of their particle chains with respect to the mechanical and magnetic loading direction. The deformation micro-mechanisms leading to the overall magnetostriction of the MRE are explained by simple full-field microstructural calculations. A brief discussion about the similarities and differences between the modeling of MREs and electro-active polymers (EAPs) is also made.