Study On The Chaining Mechanism Of Magnetorheological Fluids And Its Experimental Analysis

Magnetorheological Fluid(MRF)is a new type of intelligent material with controlled properties.Because of its unique magnetorheological effect and good rheological properties,it has been widely used in engineering applications.With the development of engineering application of magnetorheological fluid,it is particularly important to provide reliable performance of the magnetorheological fluid.The macroscopic properties of magnetorheological fluid is determined by its microscopic structure.In order to make better use of its macro mechanical properties,the corresponding mechanical models are established based on the microscopic morphology of magnetorheological fluid and the main influencing factors of magnetorheological fluid.This will be of great help to understand the mechanism of MRF,optimize the microstructure of MRF,and expand its wider field of engineering.In this paper,the magnetorheological effect was first described,and the existing chain mechanism theory was compared and analyzed.The results showed that the theory of dipole moment was simple and easy to calculate and analyze.Based on the dipole moment theory,the simplified model and exact dipole model of magnetic particles under magnetic field were deduced.Through the analysis of the macro model of magnetorheological fluid,the main factors that influence the structure of MRF were obtained,such as magnetic induction intensity,particle volume fraction and particle radius.Secondly,the numerical simulation and experimental observation on the mechanism of MRF were carried out.In the numerical simulation,a mathematical model wasestablished based on molecular dynamics.The relevant data showed that magnetic particles were mainly affected by magnetic force,viscous resistance and repulsive force.On this basis,gravity and buoyancy were added in this paper.Based on these two conditions,mathematical models were established respectively.The results of the chain of magnetic particles by magnetic force,viscous resistance and repulsive force were compared with the results of magnetic particles by magnetic force,viscous resistance,repulsive force,gravity and buoyancy.The analysis showed that the acceleration of the particles under five forces was less than the acceleration of the particles subjected to three forces,and then the force of the particles subjected to the five forces tends to be more balanced,which was closer to the actual particles into a chain of simulation.The microstructures of magnetorheological fluids under different influence factors were simulated under the mechanical model with increasing gravity and buoyancy.In the experiment,the static observation device was set up.The static device could measure the magnetic particle radius.And the image processing was carried out to extract the particle points to verify the relationship between the number of particles and volume fraction.At the same time,the microscopic morphology of the particles was observed under the different influence factors by using the self-made magnetorheological fluid.Finally,the distance between the chain and the chain was measured by the mesh between the numerical simulation chart and the experimental observation map under different influencing factors.The comparison of the simulated and experimental values showed that the relative error was less than 10%,which verifies the rationality of the established simulation model.The model could effectively simulate the microstructure of magnetorheological fluids,which was of great significance to the practical application of MRF.