This paper presents the performance of a new magnetorheological elastomer-based semi-active/passive variable stiffness and damping isolator (VSDI) in a scaled building system. The force of the VSDI can be controlled in real time by varying the applied magnetic field. To demonstrate the performance of the VSDI, four prototypes are built and utilized in a scaled three-story building. A Lyapunov-based control strategy is employed and it is demonstrated that it works well for the scaled building system under the scaled El Centro earthquake motion. Experimental results show that the VSDIs significantly reduce the acceleration and relative displacement of the building floors.

This paper presents theoretical modeling of a new magnetorheological elastomer (MRE) base isolator and its performance for vibration control. The elastomeric element of the traditional steel-rubber base isolator is modified to a composite layer of passive elastomer and MRE which makes the isolator controllable with respect to its stiffness and damping. The proposed variable stiffness and damping isolator (VSDI) is designed based on an optimized magnetic field passing through MRE layers to achieve maximum changes in mechanical properties. The controllability of the VSDI is investigated experimentally under double lap shear tests. A model employing the Bouc-Wen hysteresis element is proposed to characterize the force-displacement relationship of the VSDI. An integrated system which consists of four VSDIs is designed, built and tested. Dynamic testing on the integrated system is performed to investigate the effectiveness of the VSDIs for vibration control. Experimental results show significant shift in natural frequency, when VSDIs are activated and the possibility of using the VSDIs as a controllable base isolator.

This article is a review of models that capture the magneto-mechanical response of magnetorheological elastomers (MREs) and MRE-based systems. Where available, experimental validations of models are also discussed. The models are categorized as either particle interaction-based, magnetoelastic response-based, magnetoviscoelastic response-based, or models including the effects of environmental conditions and fatigue. Analytical, numerical, finite element, and phenomenological investigations that explore changes in stiffness and damping of anisotropic MREs are reviewed. Phenomenological models of MRE systems used in different applications are also examined.

This study presents a flexible magnetically-actuated micro fluid transport system utilizing an isotropic magnetorheological elastomer (MRE). Theoretical modeling and analysis of this system is presented for a two-dimensional model. This fluid transport system can propel the fluid by applying a fluctuating magnetic field on the MRE. The magneto-fluid-structure interaction analysis is employed to determine movement of the solid domain and the velocity of the fluid under a controllable magnetic field. The effects of key material, geometric, and magnetic parameters on the behavior of this system are examined. It is demonstrated that the proposed system can propel the fluid unidirectionally, and the volume of the transported fluid is significantly affected by some of the design parameters.

Iron particle coating can improve the behavior of magnetorheological elastomers (MREs) by inhibiting iron particle rusting; however, such a process can change physical properties of MREs such as oxidation resistance, shear modulus, and stiffness change due to an applied magnetic field. In this study, MRE samples are fabricated with regular and polymerized iron particles. To investigate the possibility and extent of these changes, polymerized particle MRE samples are made using a combination of reversible addition fragmentation chain transfer and click chemistry. Shear test sample MREs with pure elastomer and 50 wt% MRE with and without polymerization are fabricated. To observe the effect of oxidation on shear properties of MREs, pure elastomer and 50 wt% coated and non-coated samples are oxidized using accelerated oxidation procedure. Experimental results show that oxidation significantly reduces the shear modulus of the elastomer matrix. The coating process of iron particles does not significantly change the shear modulus of resulting MREs but reduces the loss of shear modulus due to oxidation.