Characteristics Study Of Hybrid Damper Based On Magnetorheological Effect

Mechanical vibration causes premature failure, unable to work or even failure of equipment, so it is necessary to take appropriate measures to reduce the harmful vibration. The damper is installed between the vibration source and the equipment which can reduce the impact of mechanical vibration on equipment effectively.Magnetorheological materials are composed of micron sized soft magnetic particles with high permeability and polymer (oil, rubber) with low permeability. Base on magnetorheological effect,magnetorheological materials are magnetizable and their mechanical performances increase at the presence of magnetic field rapidly,continuously and reversibly. So magnetorheological elastomers (MREs) and magnetorheological fluids (MRFs) can be used as vibration isolating materials to design a high performances hybrid damper based on magnetorheological effect.Mechanical performances of MREs and MRFs can be increased by changing the external current to make hybrid damper has wider vibration isolation range and achieve real-time control.The basic preparation process was finalized by analyzing the performance requirements of raw materials. Carbonyl iron powder and silicone rubber were used as basic materials for MREs. Carbonyl iron powder and two methyl silicone oil were used as basic materials for MRFs. MRFs were mixed into MREs to form hybrid elastomers which have large variation range of stiffness and damping. Particle structures were observed by using microscopy. Mechanical performances of MREs and MRFs were measured and analyzed. Experimental results show that the shear stress and apparent viscosity of MRFs increase with the increase of external current,and under the same magnetic field, the increase of the elastic modulus of MREs in the compression mode is larger than that in the shear mode.Scheme of hybrid damper was analyzed. Based on the principle of vibration isolation and analysis of performances on MREs and MRFs, the stress state of elastomers was determined. The number of the exciting coil turns was calculated theoretically. Analysis software was used to simulate and analyze the magnetic circuit of the damper, the distribution of magnetic field lines was obtained. Base on reducing the leakage of magnetic flux, the whole structure of the hybrid damper was designed and assembly.Set up vibration isolation test platform which uses two eccentric motors installed in the opposite direction as the excitation structure to generate the vertical excitation force. Real-time data collection was realized by acceleration sensor and acquisition card. Damper performances were tested by adjusting the external current and exciting frequency. The experimental results show that MRE damper and the hybrid damper have good isolation effect. It is verified that the stiffness and damping of the damper based on magnetorheological materials can be changed under the action of external current. Excitation frequency is in the range of 20-60Hz, the vibration damping rate of the hybrid damper is 43%-50%. Compared to MRE damper, the hybrid damper has wider range of vibration isolation and can achieve better isolation effect.