This article presents a novel model to portray the behavior of magnetorheological elastomer in oscillatory shear test. The dynamic behavior of an isotropic magnetorheological elastomer is experimentally investigated at different input conditions. A modified Kelvin–Voigt viscoelastic model is developed to describe relationships between shear stress and shear strain of magnetorheological elastomers based on input frequency, shear strain, and magnetic flux density. Unlike the previous models of magnetorheological elastomers, the coefficients of this model, calculated by nonlinear regression method, are constant at various harmonic shear loads and different magnetic flux densities. The results show that the new phenomenological model can effectively predict the viscoelastic behavior of magnetorheological elastomers. Also, the results demonstrate that the trend of shear storage modulus of magnetorheological elastomer based on the frequency is nonlinear from 0.1 to 8 Hz, which is predicted by the present model. The proposed model is beneficial to simulate vibration control strategies in magnetorheological elastomer base devices under harmonic shear loadings.

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Tension-compression operation in MR elastomers (MREs) offers both the most compact design and superior stiffness in many vertical load-bearing applications such as MRE bearing isolators in bridges and buildings, suspension systems and engine mounts in cars, and vibration control equipment. It suffers, however, from lack of good computational models to predict device performance, and as a result shear-mode MREs are widely used in the industry, despite their low stiffness and load-bearing capacity. We start with a comprehensive review of MREs modeling and their dynamic characteristics, showing previous studies have mostly focused on dynamic behavior of MRE in the shear mode, though the MRE strength and MR effect are greatly decreased at high strain amplitudes, due to increasing distance between the magnetic particles. Moreover, the characteristic parameters of the current models either frequency, strain or magnetic field are constant; hence, new model parameters must be recalculated for new loading conditions. This is an experimentally time consuming and computationally expensive task, and no models capture the full dynamic behavior of the MREs at all loading conditions. In this study, we present an experimental setup to test MREs in a coupled tension-compression mode, as well as a novel phenomenological model which fully predicts the stress-strain behavior of the as a function of magnetic flux density, loading frequency and strain. We use a training set of experiments to find the experimentally derived model parameters, which can predict by interpolation the MRE behavior in the relatively large continuous range of frequency, strain and magnetic field. We also challenge the model to make extrapolating predictions and compare to additional experiments outside the training experimental data set with good agreement. Further development of this model would allow design and control of engineering structures equipped with tension-compression MREs and all the advantages they offer.

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In this article, a novel bi-directional shear mode magneto-rheological elastomer–based vibration isolator has been designed, fabricated, and characterized to improve the dynamic response and identification of this class of “intellectual” mechanical devices. A heuristic embodiment has been realized in order to design such an isolator wherein both the vertical and horizontal directions can be operated only in the shear mode not only individually but also simultaneously. Two fixtures have been designed for performing the characterization of the magneto-mechanical behavior of the proposed magneto-rheological elastomer isolator in the vertical and horizontal shear modes under wide ranges of strain amplitude (4%–32%), excitation frequency (1–8 Hz), and magnetic flux density (0–220 mT). Experimental results revealed maximum relative magneto-rheological effects of 35% and 27 % in the vertical and horizontal shear modes, respectively. Furthermore, basic mathematical models of single-degree-of-freedom systems, employing the magneto-rheological elastomer–based isolator in the vertical and horizontal shear modes, have been established. The proposed magneto-rheological elastomer isolator in the vertical mode exhibited natural frequency shift of 6.1% by a small increment in the magnetic flux density which approves the potential of the proposed bi-directional shear mode magneto-rheological elastomer–based vibration isolator for vibration control applications, such as seat suspension systems.