Research On Magnetic Field Performance Of Magnetorheological Fluid Dynamometer In Operation

Magnetorheological Fluid(MRF)is a new kind of intelligent material.It is a stable suspension consisting mainly of small magnetic particles mixed with base liquor.When the magnetic field is not applied,it has better fluidity as the liquid.When the magnetic field is applied,it can quickly change from Newtonian fluid to viscoplastic body in a very short time,showing similar mechanical properties to solid.This change is also continuous,reversible and controllable.These excellent characteristics make it widely used in vehicle,medical,construction,aviation and other fields,and accepted by people.The magnetic circuit environment with good performance is an important condition for the normal work of the magnetorheological fluid device.A good magnetic environment can make magnetic flux higher within the work area of magnetorheological fluid to ensure good stability of magnetorheological fluid devices;moreover,a well-designed magnetic field environment can optimize the circuit structure of magnetorheological fluid guiding device to achieve better economy and practicality.In this paper,a magnetorheological fluid loaded magnetic field test rig was first built.A series of experiments were carried out on three magnetorheological fluid samples with volume percentages of 24.4%,31.5% and 38.7% respectively,and the influence characteristics of various factors on magnetic flux density of magnetorheological fluid were studied.Meanwhile,the magnetic field simulation was carried out by using Ansoft Maxwell software.The simulation results were compared with the experimental results to prove the feasibility of the simulation method,and provided a basis for the subsequentresearch of magnetorheological fluid dynamometer.Secondly,magnetorheological fluid was applied as a medium to dynamometer.The working characteristics and working modes of magnetorheological fluid dynamometer were discussed.According to the needs of this project,a disc type magnetorheological fluid shear dynamometer was selected.The working principle,device structure and magnetic circuit composition of magnetorheological fluid dynamometer were analyzed,and the torque model of magnetorheological fluid dynamometer was established based on Bingham fluid model.Finally,the magnetic field simulation of the magnetorheological dynamometer was carried out by the verified simulation method,and the distribution of the total distribution of the magnetic field and the magnetic field in the working gap were obtained.The distribution of magnetic force line in the working gap of magnetorheological fluid was more uniform,and the magnetic induction intensity was within the range of 120-162 m T.Based on the dynamometer device,the factors affecting the magnetic performance of the dynamometer were analyzed,such as the magnetic ring,the excitation current,the magnetic material,etc.And the magnetic circuit of the magnetorheological fluid dynamometer was optimized in the case of small change in the overall structure.