Study On Magnetorheological Impedance Characteristics And Its Sedimentation Rate Detection Method

Magnetorheological fluids can be widely used in artillery shock absorption,vehicle suspension,robots,transmission,parts manufacturing and other fields due to their magnetorheological effects.However,the magnetorheological fluid belongs to a suspension,and the density of the ferromagnetic particles is significantly greater than the density of the carrier liquid.As time changes,the phenomenon of aggregation and sedimentation of the ferromagnetic particles occurs,so that the characteristic magnetorheological effect is lost.In engineering applications,the failure of magnetorheological devices due to magnetorheological fluids may cause the magnetorheological devices to fail to function properly and cause major safety incidents.Therefore,the detection of magnetorheological fluid sedimentation in magnetorheological devices in engineering practical applications is particularly important.In this paper,a settlement detection method based on magnetorheological fluid-resistance composite impedance model is proposed and implemented.The settlement model of magnetorheological fluid resistance-compression composite is established,and the theoretical model simulation and experimental verification are carried out.The main research work of this paper includes:1.Based on the theory of micro-mechanical equilibrium equation,chain-forming mechanism,piezoresistive model,tunnel model and capacitance effect of MRF,an impedance model based on MRF resistance-capacitance combination is analyzed and constructed.The impedance model of MRF is simulated by MATLAB and Comsol software,and the relationship between the impedance of MRF and the external magnetic field is studied.Based on the impedance model of MRF resistance-capacitance composite and the shearing modes of disk and cylinder,the chain change of MRF in micro-shearing state is analyzed,and the impedance model of MRF in shearing state is deduced.2.Design and build a magnetorheological fluid impedance test platform,including two sets of disk and cylinder shear devices,and study the magnetorheological fluid impedance relationship under steady and shear conditions.At the same time,the effects of magnetic induction intensity,rotor speed,AC power frequency and electrostatic potential on MRF impedance are also studied.3.According to the traditional settlement theory,the settlement process of magnetorheological fluids is deeply analyzed.Based on the experiment and the model method of parameter identification,the settlement rate-concentration model of magnetorheological fluids is established.Combined with the impedance model of magnetorheological fluids resistance-capacitance combination,the settlement model based on magnetorheological fluids impedance is established and verified by experiments.