Dynamics Study On A Sort Of Magnetorheological Fluid Shock Absorber For Vehicle

Magnetorheological fluid shock absorber is a kind of shock absorber device, whose damping medium is Magnetorheological fluid (MRF). With the virtue of large force, small volume, rapid response, simple structure and continuous damping, MRF shock absorber has great potential in shock absorption control field. MRF is a sort of new intelligent materials whose rheological characteristics change rapidly and can be controlled easily in the presence of an applied magnetic field. Because of the characteristics, MRF has been paid wildly attention to in many fields especially in vehicle and engineering shock absorption control.Firstly, in this paper, the constitution, the mechanism and the domestic and foreign research of MRF are introduced. Damping parameter calculational formula is concluded, which reveals the internal relationship between damping force and working pressure, piston movement speed and structural parameters. It provides theory foundations in use of vehicle shock absorption control for this sort of shock absorber.Secondly, the MRF shock absorber designed for the medium-sized wounded transport vehicle is tested. The test result shows the damping capability of the shock absorber is good and the shock absorber works stable. The effect rules in damping capability about the variety of swing, frequency and pressure are acquired. The equivalent linear damping and stiffness are worked out according to the test result. The parameters of Bingham model, nonlinear biviscous model, nonlinear hysteretic biviscous model and modified nonlinear hysteretic model are recognized and four indexes to evaluate model fitting extent are established. As a result, modified nonlinear hysteretic model has best fitting precision. Then the effect rules of damping force calculation model parameter of MRF fluid shock absorber about various test condition are analyzed.In the end, the base isolation simulation of MRF shock absorber is analyzed by SIMULINK. The result shows that when simple harmonic vibration signal is inputted, damping function of MRF shock absorber is obvious which could reduce the response peak value of resonance vibration in high degree. When the input pressure is zero, transfer rate value in the response peak value of resonance vibration is 1.19. It can ensure when the input pressure is in trouble, MRF shock absorber could have well vibration absorption effect. The transfer rate reduces with the input pressure increasing. The minimum transfer rate value in the response peak value of resonance vibration is 1.05. The ratio of the acceleration root-mean-square value of vibration response to that of random signal input is used as evaluation index of vibration absorption effect. It shows vibration absorption efficiency is between 0.2 and 0.3.