Research On Friction And Wear Behaviors Of Magnetic-rheological Damper

Magnetorheological(MR)fluid has magnetically sensitive rheological characteristics.First introduced in Rabinow's Magnetic clutch,this fluid has received significant attention since 1948.Almost in seven decades,MR fluid develops from theoretical research to engineering application.Recently,research on the application of MR fluid have been widely conducted.Owning to the promising prospects in engineering application,the field-dependent MR dampers urgently require precise semi-active controlling on the damping force,which is however highly susceptible to negative influences of tribology and temperature.With changeable yield strength,MR fluid usually represents as a Bingham material,the fielddependent behaviour of which is highly similar to a dynamic friction characteristic.However,while Bingham model has been proven useful in the steady-state design and characterisation of MR dampers,the analysis of these devices needs to be consummated by taking into account the dynamic friction forces of seals in most dampers.In addition,the leakage of MR fluid will lead to environmental contamination and MR dampers' disabler.Based on the review of MR damper research,current studies mainly focus on the structural design,the simulation of magnetic field and magnetic circuit along with the calculation of damping force,etc.Surprisingly,though sealing structure has been taken into account in the design of MR dampers,researchers have paid little attention to its longevity and reliability.In other words,current studies show little regard for the tribological characteristics of seals-an important factor influencing the MR dampers' sealability.Therefore,the author takes the tribology of different rod seals in MR damper for research object.(1)According to relevant literature,the development in both MR fluid tribology and MR dampers research are systematically reviewed at home and abroad.At the same time,the factors influencing the seal and other features of MR dampers are summarized.(2)Taking the special structure of combined seals as the analysis object and Hertz contact model as the theoretical basis,the three-body abrasive wear is emphatically studied.Subsequently,based on the MR fluid,the frictional model of the seal structure is established.Meanwhile,the variation law in friction coefficient of seal structure can be deduced by the probability distribution theory of abrasive particles combined.(3)In order to verify and explore the tribological characteristics and mechanism of different seals under MR fluid,a test bed with reciprocating motion is set up.Elaborate description including the scheme principle,hardware composition and software design are presented.(4)Taking one kind of MR damper for example,with constant speed and frequency,experiments of reciprocating motions are carried out in non-piston condition.Particularly,compared to the frictional effects MR fluid has on three kinds of seals,those of silicone oil are analysed.In this paper,the wear mechanism of seals along with its variation in both frictional force and wear loss are investigated under MR fluid.For the sake of exploring the influences of MR fluid particles on the contact pressure and wear of seals,the analytical model and experimental validation are bound together in this paper.This research not only offers a new method for the improvement on sealing structure of MR damper but also provides a theoretical support to precise control on its damping force.