Magnetorheological Elastomer Isolator In Shear-Compression Mixed Mode

Vibration is a usual phenomenon in our daily life. In order to suppress the effect ofnuisance vibration on precision instruments and equipments, it is necessary to designvibration isolator or absorber. The isolation device commonly used for small equipmentis a rubber isolator. The rubber isolator works without energy input at low cost.However, one type of rubber isolators operates with a passive work model and usuallyworks only in a narrow frequency range with good damping effect. If the outsidevibration frequency ranges change, the isolation performance of the rubber isolator willbe greatly reduced, even leading to a “resonance phenomena”. Magnetorheologicalelastomer (MRE) is a kind of smart materials whose stiffness and damper could becontrolled by the magnetic field quickly and reversely. Vibration isolators made of MREshow great promising applications.In this paper, MRE is firstly made and tested under shear and compression modefor the vibration isolator. Then, a vibration isolator of mixture mode is designed, and anexperiment is carried on to test its performance of vibration isolation. Specific works asfollows:Firstly, according to application requirement of mixed mode isolator, the MREwith specific components is made in this work, and tested the characters of the MRE inspecific amplitude and frequency of shear mode and pressure mode, respectively.Secondly, according to working principle of isolators, a vibration isolator of mixturemode (compression and shear mode.) is designed, and an experiment is carried on totest its performance of vibration isolation. The MRE isolator is composed of two piecesof MRE. One works in shear mode, the other works in compression mode. Excitationmagnetic field of the isolator is generated by the excitation coil，it direction is in parallelwith the pressure direction and vertical with shear direction. The stiffness of the isolatoris controlled to achieve semi-active variable stiffness of the isolator by adjusting theexcitation current to control the modulus of the MRE. Because of compression modeMRE modulus is higher than the shear mode; the structure can effectively reduce thestatic strain caused by the quality of the isolation device. Finally the experimentalresults show that the design of MRE isolator can effectively change the natural frequency of the vibration isolation system. Variable stiffness range of the vibrationisolation system is increased with application current increasing.