Research On Power Transfer Mechanism Of Magnetorheological Fluids Transmission System

Magnetorheological fluids(MRFs)is a new kind of solid-liquid two-phase intelligent material,whose working mechanism is controlled and regulated by an external magnetic field.Magnetorheological(MR)transmission is a new type of transmission technology,which uses MRFs as power and motion transmission mediums,MR transmission has many advantages,such as a quick and reversible response,simple control and low energy consumption,as well as high anti-interference ability,etc.Therefore,it possesses a broad application prospect in the fields of soft start,soft brake,stepless speed control and overload protection for mechanical equipments.According to the problem of power transfer mechanism of MRFs transmission system is not clear,this dissertation conducts an in-depth research from the following aspects.The mechanism of MR effect is researched,the influence characteristics of magnetic field intensity on MR effect are obtained.The material selection principle of MRFs and the influence characteristics of materials with different properties on the performance of MRFs are analyzed,the preparation method of MRFs is researched,five types of high performance MRFs containing Nano-Fe₃O₄ spherical and magnetic particle additive are prepared,the mass fraction of Nano-Fe₃O₄ spherical and magnetic particle additive in MRFs with the best comprehensive performance is determined by experiments.The force of soft magnetic particle and the energy of soft magnetic particle system under the action of a magnetic field are obtained by theoretical analysis,the motion equation of soft magnetic particle and energy equation of soft magnetic particle system are established.A three-dimensional numerical simulation strategy of microstructure evolution characteristics for MRFs,and the acceleration method of the simulation are researched,the microstructure evolution characteristics of MRFs with large particle numbers under different magnetic induction intensities are numerically simulated in three dimensions,the microstructure evolution laws of MRFs with different particle numbers under different magnetic induction intensities are obtained.The experimental system and scheme for researching the microstructure characteristics of MRFs based on industrial CT are designed,an industrial CT scanning test bench for MRFs is established,the industrial CT scanning experiments of MRFs with different particle volume fractions under different magnetic induction intensities are conducted,the overall,local and internal three-dimensional microstructure characteristics of MRFs under the action of magnetic fields are obtained,the variation laws of particle chain lengths and the distribution characteristics of soft magnetic particles are quantitatively captured.The working mode and feasibility of the integrated design of squeeze-strengthening technology in MR brake are researched,a new type of squeeze-strengthening MR brake is developed,the magnetic circuit of the brake is designed and analyzed,the rationality of the magnetic circuit design is verified,and the influence laws of the main design parts on magnetic induction intensities of working gap are obtained by electromagnetic field simulations and experiments.The braking,squeezing and temperature test system for MRFs is designed,the performance test experiments of the squeeze-strengthening MR brake are conducted,the mapping characteristics of braking torques on temperature fields,the variation characteristics of MRFs temperature under different slip powers and different heat dissipation conditions,the enhancement laws of braking torques under different squeezing pressures,and the working performance of squeeze-strengthening MR brake under squeezing actions are obtained,the reliability of the designed squeeze-strengthening MR brake,and the feasibility of the integrated design of squeeze-strengthening technology in the MR brake are verified.Research results obtained in this dissertation play an important guiding significance to the thorough study of power transfer mechanism of MRFs transmission system,and provide a technical support for the development and application of high-power MR transmission devices.The dissertation has 124 figures,22 tables and 137 references.