Design And Research Of Magnetorheological Fluid Damper

With rapid developments of modern industrial cities and the expanding of city scale, the influence of vibration on environment of metropolitan life and work has gradually attracted much attention of the people. Actually, the key feature in the urban traffic system is the common mechanical vibration whose damages on human body are the bones vibration and the influence of some mechanical noise. Hence, in order to promote the comfortability of our daily travel, a variety of traditional shock absorbers appear, such as the automobile suspension system whose damping system is often composed of hydraulic shock absorber and spring shock absorber, or car seat vibration system, the composition of its damping system is usually characterized by spring shock absorber with rubber vibration isolation cushion.With rapid developments of science and technology, the research of intelligent materials and the related devices has become a very important research direction, and the smart materials replace gradually the existing traditional ones. As one of the smart materials, magnetorheological(MR) suspension found by the American scholar Rabinow in the 1950s is paid much attention since 1990s. The physical and rheological properties of MR suspensions are changed with the variation of the external magnetic field and show some excellent characteristics such as continuous, rapid, reversible, and precisely controlled. It has been found that magnetic particles are randomly distributed in the absence of the external magnetic field, suspending independently and touching with each other, i.e., MR suspensions exhibit liquid state. Whereas when an external magnetic field is applied, the magnetic particles in the fluid are magnetized, dipole moments are produced, and the particles can be considered magnetic dipoles approximately, so that the magnetic particles approach to each other under the influence of the external field, and align along the direction of the magnetic induction intensity to form chains or columns, namely solid-like state. Based on the rapid transition between solid and liquid states with and without the external magnetic field in a millisecond level, and its reversibility, MR suspensions are gradually applied in shock absorbers which are tested by means of experiments.In this thesis, the influence of pressure and the external magnetic field on phase separations of MR suspensions were studied by computer simulation. Based on the simulation results, MR dampers were designed, an ultrasonic transducer was applied to investigate the damping performances. The content of the thesis is set as follows:(1) Composition, physical mechanisms and preparation of MR suspensions;(2) Monte Carlo simulation of phase separations of MR suspensions;(3) Theoretical design of the MR damper;(4) Part ? of MR damper experiment includes the make of its entity and the design of coil magnetic circuits;(5) Part ? of MR damper experiment includes the vibration test and the analysis of damping performance.(6) Conclusions and outlook.