Magnetorheological Fluids Employing Substitution of Nonmagnetic for Magnetic Particles to Increase Yield Stress

Abstract

Magnetorheological fluids (MRFs) were synthesized to investigate potential enhancements in magnetorheology when replacing magnetic particles with nonmagnetic micro-scale glass beads, that is, to increase yield stress, while reducing density and particle settling rate. Two MRF samples having 40 volume percent (vol%) of particles were synthesized: MRF-40 and MRF-37. MRF-40 had 40 vol% of carbonyl iron (CI) particles, and MRF-37 contained 35.7 vol% of CI particles and 4.3 vol% of glass beads. A comparative study of MRF characteristics was conducted to determine the impact of the nonmagnetic glass beads on yield stress, as well as viscosity, and settling rate. Both MRFs were characterized as follows: 1) magnetorheology as a function of magnetic field, 2) sedimentation rate in a fluid column measured using an inductance-based sensor, and 3) cycling of a small-scale damper undergoing sinusoidal excitations at frequencies of 1 Hz for characterization and 4 Hz for endurance tests. Optical micrographs of the glass beads were taken before and after damper cycling to assess durability. The MRF with glass beads initially doubled the damper yield force (relative to the MRF with no glass beads) at high field strengths in damper tests. This increase in yield force did not persist as the damper was cycled in an endurance test and the glass beads eroded. Fe particle sedimentation rate was reduced by about 4% in the MRF with glass beads.Index Terms-Magnetorheological fluids, nonmagnetic glass beads, yield stress.

Magnetorheology: a review

“…big or small, spherical or not spherical, magnetically soft or hard, magnetic or non-magnetic, mechanically hard or soft, etc.). By using bidisperse MRFs one can improve dispersion stability, 95 reduce the off-state viscosity, 96 increase the MR effect 95,[97][98][99][100][101] and minimize the sedimentation. 97,98 First papers in this field explored mixing particles of different sizes (bimodal MRFs) with at least one particle in the micrometer range.…”

“…By using bidisperse MRFs one can improve dispersion stability, 95 reduce the off-state viscosity, 96 increase the MR effect 95,[97][98][99][100][101] and minimize the sedimentation. 97,98 First papers in this field explored mixing particles of different sizes (bimodal MRFs) with at least one particle in the micrometer range. In these references two main groups can be distinguished depending on the particle diameter ratio between 74 CIP/PANI B2000 Spheres CC grade from BASF/one step in situ oxidation polymerization process Chen et al 75 CIP/graphene oxide B1000 Spheres CM grade from BASF/Hummers' method Dong et al 77 Sepiolite/magnetite Unknown Rods Sigma Aldrich/coprecipitation Hajalilou et al 78 CIP/Ag B1000 Spheres Unknown/Green method Kim et al 79 CIP/polyamide 6 B4500 Spheres CD grade from BASF/in situ polymerization method through a phase inversion method Kim et al 80 CIP/PGMA B2000 Spheres CC grade from BASF/dispersion polymerization Kwon et al 81 CIP/xanthan gum B5000 Spheres ISP/solvent casting method Kwon et al 82 Magnetite/PANI Unknown Spheres Micelle-assisted self-assembly method Nguyen et al 83 CIP/silica B4500 Spheres CD grade from BASF/Stöber Park et al 84 Magnetite/PMMA B10 Spheres Coprecipitation/double miniemulsion method Park et al 85 Magnetite/polypyrrole B500 Spheres Hydrothermal/in situ polymerization Piao et al 86 PANI/magnetite Unknown Fibers Chemical oxidative polymerization/precipitation Chae et al 87 PS/magnetite B500 Spheres Surfactant-free Pickering emulsion polymerization/Sigma Aldrich Fang and Choi 88 CIP/MWCNT B4500 Spheres CD grade from BASF/using 4-aminobenzoic acid Fang et al 89 CIP/PANI/MWCNT B4500 Spheres CD grade from BASF/dispersion polymerization and solvent casting Fang et al 90 CIP/PS/MWCNT B4500 Spheres CD grade from BASF/dispersion polymerization and emulsification Liu et al 91 CIP/silica B4500 Spheres CD grade from BASF/sol-gel method based on the silane grafted CIP in two steps Liu and Choi 92 PMMA/magnetite B10 000 Snowman Seeded polymerization/coprecipitation Liu and Choi…”

Magnetorheological fluid composites synthesized for helicopter landing gear applications

“…By doing so, a landing gear can exploit the field adjustable yield stress to control the stroking load of a landing gear oleo to minimize impact loads transmitted to the aircraft fuselage. Magnetorheology depends on several factors including particle shape (Bell et al, 2007), and coatings (Fang and Choi, 2008) or passive particles (Powell et al, 2012). However, in this study, the focus will be on the feasibility of synthesizing MRFs employing three different carrier fluids, which are hydraulic oils licensed for use in landing gear .…”

Magnetorheological composite materials (MRCMs) for instant and adaptable structural control

“…Magnetorheological elastomers (MREs), composed of ferromagnetic nanoor micro-particles embedded in a stiff polymeric matrix, have also been used as a core layer to produce smart, adaptive sandwich panels and beams with promising results (Yalcintas and Dai 2004;Lee et al 2014;Hasheminejad and Shabanimotlagh 2010). Basic composite MR fluids have been produced by adding a small volume of non-magnetic microparticles, such as polystyrene or glass spheres, to traditional MR fluids (Popplewell and Rosensweig 1996;Powell et al 2012) to enhance colloidal stability of the fluid and increase yield stress, and set-on-demand concrete has been investigated by adding ferromagnetic particles to cement paste during the mixing process and using an external magnetic field to influence the fresh-state properties (Nair and Ferron 2014). However, while useful for controlling the fresh-state properties of concrete, note that the dispersed magnetic particles cannot be used to influence properties of MR concrete after setting has occurred because the magnetic particles cannot freely rearrange themselves within the stiffened concrete matrix.…”