Research On Vibration Absorber Of Rotor Based On Squeezing Magnetorheological Damper

High speed rotating machine can produce vibration during working.The vibration is more intense when across the resonance range.The excessive mechanical vibration will cause the failure of the components and reduce the working life of the machine.So it is necessary to analyze the vibration damping of the vibrating system.Magnetorheological fluid(MRF)is a new kind of intelligent material,which suspends micro sized soft magnetic particles in carrier liquid.At the appearance of the magnetic field,the particles inside MRFs can live themselves to form chain structures and then magnetorheological effect appears.The apparent viscosity can be controlled at the appearance of the magnetic field,and then we can use it in dampers to change the stiffness and damping of the dampers.Under the action of the dampers,the acceleration of the rotor can reduce greatly and ensured the stability when crossing the resonance area.The theory and the principle of vibration reduction of the MRF damper were analyzed in the dissertation.Based on the characteristic of the extrusion mode can provide higher yield strength with the same magnetic field,set the extrusion mode as the working mode of the MRF damper.The expressions of stiffness and damping were obtained according to analyse the working state of the rotor system.The numerical solution is carried out by MATLAB,and we can obtain that the natural frequency of the rotor system is mainly affected by the support stiffness,while the rotor vibration amplitude is mainly affected by the damping.The performance of MRF is tested and analyzed,and determined the structure of squeezing MRF damper.Carbonyl iron powder and dimethyl silicon oil were used as basic materials for MRFs.The parameters of MRF such as volume fraction,current and shear rate were analyzed by rheometer.Experimental results show that the stress increases with the increase of volume fraction,external current and shear rate.The structure of the squeezing MRF damper was determined by combining the performance of MRF and the working conditions of the rotor system,and the key structural-elastic rod is simulated and analyzed by ANSYS/Workbanch.The results show that it can meet the strength requirements.The number of the exciting coil turns was calculated theoretically and the magnetic field lines and magnetic induction intensity were obtained by the finite element software.The results show that the simulation results conform to the theoretical design.Set up vibration control experiment platform to test the vibration absorbe characteristics,and made the vibration control scheme.In the experimental process,the volume fraction and magnetic field intensity of MRF were used as variables to test and analyze the vibration acceleration of the rotor system.The experimental results show that the acceleration decay rate of the system increases with the increase of volume fraction and excitation current.Based on the above analysis,the vibration control scheme of the rotor system is determined and then it was tested and analyzed.Compared to the results with no MRF,the acceleration attenuation rate can be reduced to 41.6%under the scheme.It can cross the resonance range smoothly and achieve better vibration reduction effects.