Friction Mechanism And Experimental Study Of Sealing Element Of Magnetorheological Damper

Magnetorheological fluid(MRF)is a new kind of intelligent material,which is a suspension formed by magnetic particles of micron size distributed in a non-magnetic liquids.The magnetorheological damper based on the unique magnetorheological effect of magnetorheological fluid has been widely used in major engineering fields such as carrier vehicles,aerospace spacecraft and bridge design.As the magnetorheological fluid contains magnetic particles,the reciprocating movement of the piston rod inevitably brings it into the sealing area,resulting in wear failure of the sealing element.Leakage caused by seal failure has always been a difficult problem in the production and use of magnetorheological dampers.In the application of damper,NBR O-ring is often used as reciprocating seal element.Therefore,based on fluid lubrication theory,this paper conducts theoretical and experimental research on the friction and wear characteristics of NBR O-ring under the effect of MRF.The main research contents of this paper are as follows:(1)The current research status of magnetorheological fluid tribology and the research progress of establishing mathematical model based on the reciprocating seal theory were briefly described and the sealing mechanism and wear failure of O-ring were analyzed and summarized.(2)Considering three states of elastic,elastic-plastic and plastic deformation of sealing ring under the action of magnetic particles,a friction model of particles under the action of multiple particles is established;Considering the load-bearing function of the micro-convex body,the friction model of the micro-convex body is established.(3)Based on the theory of hydrodynamic lubrication,the coupling particles and the bearing capacity of micro-convex bodies were used to establish the mathematical model of O-ring affected by carbonyl iron particles under the effect of MRF,and the numerical calculation was conducted by using MATLAB software.The aim is to analyze the influence of magnetorheological fluids containing different particle sizes and different particle mass fractions on the friction characteristics of O-rings.(4)The magnetorheological damper sealing friction and the servo motor driven wear test bed were designed and built.The structure design of the magnetorheological damper,the design of the motion control system of the test bed and the design of the data acquisition system are studied in depth.(5)Magnetorheological fluids were prepared with different mass fractions and particle sizes,then,the mathematical model was experimentally verified based on the built friction and wear test bench of sealing element of magnetorheological damper,and the wear surface morphology of O-ring under the effect of magnetorheological fluid was observed by ultra-deep field microscope,so as to further explore the friction and wear mechanism of O-ring under the effect of magnetorheological fluid.