Abstract:
Owing to its benefit of changing stiffness, Magnetorheological Elastomers (MRE) can be effectively used as base isolator in buildings and bridges to resist unpredictable loading conditions e.g. seismic activities. This research aims to study the effects of using Iron nanoparticles in silicon rubber matrix on dynamic properties of MRE’s and to make MRE more adaptable to seismic forces, specifically at high strains. Micro-sized iron particles were reduced to nanoparticles using a planetary ball milling machine. Samples, using only microparticles, nanoparticles & a mixture of nano & microparticles (hybrids) were prepared for different percentage concentrations. The experimental test rig was set up for dynamic shear testing under known amplitude, frequency, and magnetic field, summing up to total 540 tests. The experimental results revealed that the use of nanoparticles had a significant increase in the effective stiffness by 13 % at higher strains and low flux values for hybrid MREs. Further attaining MR effect at a higher frequency is difficult using microparticles however for hybrid MREs, the MR effect was higher for higher frequency. The maximum MR effect was observed for samples with 40% iron content. Key Words: Magnetorheological Elastomer, nano particles, High strains, Mullin effect, Base isolator, Planetary ball milling, Magnetorheological effect.
