Influence of working gap on magneto-rheological coupler

This paper studies the influence of working gap on the magnitude and distribution of the magnetic field density and the shear stress of a magneto-rheological coupler.The results of FEA and experiments indicate that the magnitude of the magnetic field density decreases with the increase of the working gap,while the distribution of the magnetic field density and the shear stress becomes more uniform along the axial direction.Because of the magnetic saturation and the existence of the stress yield of the magneto-rheological fluid,the working gap,for the range of 0.2 to 1.2mm,has limited influence on the magnetic flux density and the stress.The further computational results show that the transmission torque only decreases 25% in this procedure.Base on these findings,the working gap should be chose properly to get a sufficient magnetic field and transmission torque for a given device with consideration of machining and assembling cost associated with a smaller working gap.