Magnetorheological Rubber Shock Absorber Design

Over the past three decades, a great deal of interest has been generated regarding the use of structural protective systems to mitigate the effects of dynamic environmental hazards on civil engineering structures. These systems usually employ supplemental damping devices to increase the energy dissipation capability of the protected structure. One of the most promising new devices proposed for structural protection is magnetorheological (MR) fluid dampers. MR fluids, characterized by a dynamic yield stress in the presence of a magnetic field, have been viewed as a kind of important actuating material in intelligent structures of MR fluid dampers. Due to their virtues of fast response, low energy dissipation, outstanding rheological effect, less sensitive to contaminants and stability in temperature, MR fluids have been proposed for wide variety of vibration dampers for active damping.In view of MR fluid damping techniques and rubber damping techniques, some MR-rubber damping techniques, including system theory, experimental investigation, design method, manufacture technique, and models of the dampers, etc. have been presented in this dissertation. This dissertation are divided into seven chapters:The purpose and significance of this study are expounded in the first chapter. The application prospect and development tendency of MR fluids and MR devices in the domain of engineering have been pointed out, on the basis of systematically summarizing of state of MR devices and MR technique. In view of existing state of MR techniques, the goals and contents of this dissertation have been put forward briefly.In the next four chapters, according to the working modes of MR devices, combining the ohm's law of magnetic circuit and the design theory of non-steady magnetic circuit, magnetic structures of the MR damper have been worked out. To emulate the performance of conventional shock absorber, a MR-rubber damper and its testing devices were designed and fabricated. An applied magnetic field increase the yield stress of MR fluids in flow annular passages, which alters the velocity profile of MR fluid in the passages and raise the pressure gradient between low cavity and high one at some given flow rates. The motion equations, derived from equation in hydromechanics employing the Newtonian fluid model and the Bingham plastic model, demonstrate that damping force can be controlled by changing the magnetic field in the gaps.In the sixth chapter, the performances of MR-rubber dampers designed and fabricated at Huaqiao University have been tested in Lab, including schematics of electric current of the coil vs. displacement of piston head, electric current of the coil vs. power spectrum of damper, etc. for some given frequences of vibration. The experimental results demonstrate that damping force offered by MR damper increases with the increase of electric current of the coil.Some conclusions and prospects are given in the last chapter. The main achievements of the dissertation are summed up and some directions of future improvement about structure of MR rubber damper are pointed out.