Studies On The Characteristics Of Magnetorheological Adjustable Damper

Compared with passive suspension, the vehicle semi-active suspension improves both riding comfort and vehicle maneuverability. As a kind of promising damper, magnetorheological (MR) damper has arosed great attention. There are some MR Dampers for saled and used on the top grade vehicles in the foreign, but questions have been found such as the MR fluid was unsteadiness, the temperature rose during the working time,Characteristic of Response,wear of the damper,and so on. Studies on the MR Damper were origination moment in our country. The development trend of the vehicle suspension and damper technology are introduced in this paper. The research status and development course about the MR fluent and MR Dampers are summarized. According to the questions of the MR Damper, characteristic of the damp,MR fluid,temperature and response time have been studied with experiment and theory method which were helpful to improve the performance of the MR Damper.The common theory models of the MR Damper were analyzed to find the change rule of the parameters. Experiment has been done to test the damp characteristics of Lord RD-1005-3 MR Damper. Results show the controllable character and delay character of the MR Damper. Curve about coulomb damper force and current were drafted as the triangle power were used to activate the damper. As the current is in small scope, there are linearity relation between the coulomb damper force and current.Based on the flux model of the MR Damper, turbulent flow, calculation theory, initial and boundary conditions and mesh creation, a three dimension dynamic model of the flow mode MR Damper has been established in Fluent. The pressure field and velocity field have been simulated. Result shows that the velocity field was affected by the shape of the piston and the pressure field has influence on the damper force.Temperature characteristic about MR Damper has been researched. Theory model based on the experiment were established which can be used to calculate the temperature diversification course. Results of the experiment and theory analysis show that the current and activate way is the main reason which result in the temperature rising during working. Suspension system vibration model was established, theory calculation model about the heat capacity of MR Damper in the fuzzy semi-active suspension were researched, Effect of the vehicle speed, road grad and suspension parameters has been analyzed. The heat of MR Damper was due to the road grade, vehicle speed, unsprung mass and tyre stiffness. Sprung mass has little influence on it. Suspension parameters and characteristic of heat should be thought over when design the MR Damper used in the semi-active suspensions.Response time of MR damper and the effect of operating parameters have been investigated. Inductance and resistance of the electromagnetism loop, viscidity of MR Fluid, flat clearance have significant effect on the response time of the damper.Using a triangle wave to maintain constant velocity across the damper, In this experimental study, a commercially available MR damper was tested and the response time was found. The parameters include operating current and system compliance. The results indicate that compliance and operating current still have effect on the response time of the damper.Based on the motorial steability theory of dynamic time delay system, method to conclude the critical time delay's numerical value of MR suspension system was put forward, factors that effect the dynamic performance and reasons of lose steability of MR suspension was analyzed, relations between critical time delay value and unajustable damper's force,ajustable damper's force was analyzed,all the results offer a foundation to the study of the time delay controlled theory in the suspension system.Based on theory to solve the critical time delay numerical value,it used fuzzy internal model control to give a compensate control of the MR-suspension,the suspension system controlled by fuzzy controled method and the compensate controlled method were simwed,all the results indicated that the acceleration of the sprung mass reduced, the tyre's dynamic load were amended if suspension controlled by compensate method, suspension's compensate controlled method that base on the MR damper can amend the suspension's capability.