Study On Key Technology Of Magneto-rheological Vibration Isolation System

Magneto-rheological (MR) fluid is a kind of smart material got great development in recent years. Under the strong magnetic field, it can be transformed within millisecond from flow state into semi-solid state with controllable yield strength and reversible state transformation. Having high controllability, strong damping force, broad operational temperature range, fast response time and very low power, MR dampers can be made the semi-active vibration isolation systems as required. One of the key researches for nonlinear damping characteristic of MR damper is to establish right dynamic model meeting the requirements of real-time control as well as the structure design for the application of MR damper. The another is to establish effective real-time control strategy in vibration isolation system.This dissertation pays more attentions on the detailed analysis of MR vibration isolation system, especially on setting mathematic model of the twin tube MR damper, obtaining real-time control strategies, validating the control strategies by testing the quarter automobile model.The more detailed researches are as follows:1. The equilibrium equations of MR damper based on Navier-Stokes equations and Bingham plastic characteristics are set up after the properties of MR fluids are analyzed. The rheological behavior of MR fluids is analyzed by axial symmetric and parallel plate flow models.2. The magnetic fields in MR damper are calculated by FEM and electromagnetic theory, with which the average magnetic flux density of the damper fluid gap is gained. This flux density is very important for the magnetic circuit design of MR damper.3. The twin tube MR dampers used in automobiles are analyzed based on the experimental data. This twin tube damper model has clear physical meanings, whose physical parameters can be obtained via experiment data. The expressions for the model are very conviently applied in the actual controller for MR damper. The phenomenon of the hysteresis in MR damper are found to relate with the acceleration,which is confirmed by the dynamical experiments for MR damper by changing values of the electric currents and accelerations.4. The feedback control and the effect of time delay on feedback control are studied. The new semi-active vibration control and fuzzy control strategies based on Lyapunov stability theory, and the control strategies based on acceleration and velocity feedbacks are put forwards. The simulation indicates that the proposed controllers are more effective in the performance of vibration isolation than the traditional Skyhook control system and the superiorities of these proposed controllers are further compared.5. The effectiveness and superiority of the proposed MR semi-active control strategies...