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A tunable stiffness and damping vibration isolator based on magnetorheological elastomers (MREs) is developed. In this isolator, four MRE elements are used as the tunable springs, whose stiffness can be controlled by varying the magnetic field. A voice coil motor, which is controlled by the relative velocity feedback of the payload, is used as the tunable damper of the isolator. Under the combined ON–OFF control, the proposed vibration isolator shows satisfying isolation effect. The experimental results indicate that the responses of the payload are suppressed significantly in comparison to the passive system. The transmissibility of the payload around the resonant frequency is decreased by 61.5%. The root mean square (RMS) value and the maximum value of the displacement responses of the payload are decreased by 36.0% and 50.0%, respectively. In addition, the RMS values and maximum values of the velocity responses are decreased by 45.4% and 52.5%, respectively. [ABSTRACT FROM AUTHOR]

This article presents the design and analysis of a novel dynamic stiffness tuning vibration absorber working with Magnetorheological elastomers (MRE). In this design, the MRE worked in a shear mode, but its MR effect was significantly enhanced by dynamically squeezing the sample thickness with an embedded piezoelectric (PZT) actuator. With this design, both the quasi-static magnetic field and the PZT driven dynamic squeeze strain in the direction of particles chain were properly adjusted to control the vibration of the primary system. The vibration suppression capabilities were theoretically analyzed by the harmonic analysis. A combined control strategy (the tuning strategy and the ON-OFF strategy) and the control system were developed to suppress the vibration of the primary system. The simulation results indicate that the proposed MRE-PZT-based dynamic stiffness-tuning dynamic vibration absorber (DSTDVA) exhibits more effective suppression capabilities than those conventional MRE-based quasi-static tuned vibration absorbers; the stronger the enhanced effect of squeeze strain on MRE's shear storage modulus is, the more effective vibration suppression capabilities the proposed MRE-PZT-based DSTDVA has. [ABSTRACT FROM AUTHOR]

This paper presents two kinds of magnetorheological elastomers (MREs). One is composed of appropriate silicon rubber, carbonyl iron particles and some other materials. It is cured under a strong magnetic field at a room temperature. Its shear modulus change from 0.34MPa at zero magnetic field to 3.34MPa at 1T magnetic field, the relative MR effect reaches 878%. Such high MR effect has not been reported until now. The other is composed by appropriate natural rubber, carbonyl iron particles and some other materials. After the compositions are mixed in a two-roll mill, they are cured under a strong magnetic field according to a temperature profile. The increment of its modulus reaches 3.6MPa, and the relative modulus increment is 133%. Their mechanical properties are also evaluated. All observed results show that the fabricated MREs are utilizable. They have successfully been utilized to adaptive tuned vibration absorbers, which will serve for vibration absorption of vehicles. [ABSTRACT FROM AUTHOR]

Magnetorheological elastomers' mechanical property is greatly influenced by the microstructure of magnetizable particles embedded in the rubber matrix. When synthesizing magnetorheological elastomers, usually the mixture is cured in the presence of a magnetic field and particles are arranged in chainlike or columnar structure after the crosslink, in order to get remarkable effect controlled by the magnetic field. However curing under the magnetic field will face some problems, e.g. the preparation will become not convenient. In this paper magnetorheological elastomers are prepared in various volume fractions in the absence of a magnetic field. Their dynamic viscoelastic properties are tested by a system designed by ourselves. Their microstructures are observed by scan electronic microscope. Finally the inherent relation is revealed between the magnetoviscoelasticity and the distribution of particles in the matrix as well as the components of the mixture and the chemical technique. A kind of typical microstructure is found to be relative to the magnetoviscoelasticity of magnetorheological elastomers prepared in the absence of a magnetic field. This study also provides a guide when designing and preparing this kind of smart materials. [ABSTRACT FROM AUTHOR]