Magnetorheological Elastomers in Finite Deformations: Micromechanics and Instabilities
Stephan Rudykh (Massachusetts Institute of Technology), Katia Bertoldi (Harvard University)
Soft Materials and Structures
Tue 4:20 - 5:40
Barus-Holley 158
We study the behavior of magneto-rheological elastomers (MREs) undergoing large deformations in the presence of a magnetic field. These composite materials comprise soft elastomeric matrix and rigid magnetizable particles. Indeed, the performance of MREs strongly depends on the distribution of the particles. For example, MREs with periodic microstructures can exhibit stronger magneto-mechanical coupling than the ones with random distribution of magneto-active particles. The behavior of the latter is estimated by application of a recently developed homogenization technique for magneto-active composites. In contrast, finite element models are used to determine the response of the periodic MREs. Moreover, we analyze the behavior of the MREs where the particles are aligned in chain-like structures. These structures are formed due to the presence of a magnetic field during the curing stage of MRE manufacturing. Remarkably, the anisotropic MREs exhibit stronger stiffening when subjected to external stimuli. We derive a compact model for the behavior of these materials. The model is based on an exact solution for layered MREs. The model agrees nicely with the available experimental data. Further, we make use of the model to identify the critical magneto-mechanical loadings associated with the onset of instabilities. We analyze the role of the magnetic field and the anisotropy direction, as well as material parameters and constituent volume fractions on the stability of the anisotropic MREs. The examples are given for different modes of finite deformations for both in-plane and fully 3D settings. References S. Rudykh and K. Bertoldi, “Stability of Anisotropic Magnetorheological Elastomers in Finite Deformations: a Micromechanical Approach.” J. Mech. Phys. Solids, 61, 949–967 (2013)