Fabrication and Characterization of Natural Rubber‐Based Magnetorheological Elastomers at Large Strain for Base Isolators

Abstract

To withstand harsh conditions and have a moderate strength, it is desirable to use natural rubber for base isolators. In addition, previous studies have measured the magnetorheological (MR) effect under low‐strain range, mostly within 10%. In the reality, it is necessary to evaluate the performance under large‐strain range for base isolators. In this study, material properties of natural rubber‐based MREs with various mixing ratios were evaluated under large‐strain range (~100%). In the first step, MREs with various iron ratios were fabricated and evaluated to observe the MR effect according to the ratio and arrangement of iron powder. As a result, the highest MR effect (22.0% at 100% strain) and damping ratio (10.29%) were observed in the sample with 35% iron ratio, and the MR effect of the isotropic and the anisotropic MRE did not show significant difference under large‐strain (50~100%). In the second step, MRE samples containing the optimum iron ratio (investigated in the first step) and various mixing ratios of carbon black and naphthenic oil were prepared. As a result, the MRE containing 60phr of carbon black and 40phr of naphthenic oil had the highest MR effect (33.8% at 100% strain). Compared to the case without additives, it showed an obvious improvement.