Numerical and Experimental Investigation to Reduction of Sedimentation of Particles in MRFs with Permanent Magnets

摘要

A method to reduce the sedimentation of the ferromagnetic particles in magnetorheological fluids (MRFs) is studied with numerical simulation and experiment. It shows that, making use of the magnetic field generated by a permanent magnet put simply above an MRF, the sedimentation of the particles in the MRF can be reduced remarkably. The magnetic force on a ferromagnetic particle and that on a particle chain are computed with the finite element (FE) code ANSYS. It reveals that the magnetic force on a particle-chain is much larger than the sum of the magnetic force on each individual particle in the chain without considering the interaction between the magnetized particles. The improvement of the sedimentation stability of MRF samples with permanent magnets is also investigated experimentally with a specially designed testing device, and it is found that a proper choice of the permanent magnet and the distance between the MRF sample and the permanent magnet can efficiently improve the sedimentation stability of MRFs.