Research On MR Micro-mechanism And Wall Slip Characteristics

Magnetorheological fluid is a new type of intelligent material,which is mainly composed of three parts: soft magnetic particles,carrier fluid and additives.It has unique MR effect.Magnetorheological transmission technology is a new kind of power transfer technology.It has many advantages,such as rapidly,reversible,simple control and low energy consumption,etc.Therefore,it has a broad application prospect.According to the existing problems in current studies of MRFs and MR transmission,the following aspects have been deeply studied in this paper.The composition,performance evaluation index and preparation method of magnetorheological fluid are expounded.A uniform magnetic field generator is designed.The magnetic circuit of the device is analyzed by simulation and experiment.The microstructure of the magnetorheological fluid is observed by high definition microscope.The influence of magnetic field strength and particle mass fraction on the microstructure of magnetorheological fluid is obtained.On the basis of understanding the meaning of the magnetic dipole,the characteristics of the single chain dipole model,the double chain dense dipole model and the finite element model are summarized.Based on the finite element model,the error characteristics of the single chain dipole model are analyzed.The influence rule of particle size,particle spacing and magnetic induction intensity on shear yield stress is summarized,and based on that,the single chain dipole model is corrected.The composition and working principle of the dynamic shear yield stress tester are introduced in detail,and the conversion relation between torque and shear yield stress is derived.The effect of mass fraction,particle size and magnetic induction intensity on shear yield stress is studied by experiments,and single chain dipole model,modified single chain dipole model and experimental results are compared,and the rationality of single chain dipole model correction is verified.The cause of the wall slip phenomenon of the magnetorheological fluid is explained.The magnetic force of magnetorheological fluid particles and the wall surface is simulated and analyzed.The result reveals the influence of permeability of wall material on wall slip.The influence of wall radial groove density,groove width and groove depth on wall slip characteristics is studied by means of simulation and experiment.