If magnetorheological (MR) fluids are stored in porous materials, when excited by the external magnetic field, MR fluid will be drawn out and produce MR effect, which could be used to solve the following problems of the MR damper, such as the seal, volume and the cost of MR fluid damper. In this paper, the effect of structure of metal foams on the performance of MR fluid is investigated; the relationship between the penetrability and the porosity of the metal foams is measured, the change of MR fluid performance flowing though the metal foams is obtained. It shows that, after flowing through metal foams, the change of performance of MR fluid is about 2.5%. Compared to the sponge, the porous metal foams have the obvious advantages in high porosity and rigidity, which provide a convenient and low-cost way to design the MR damper.

As a kind of smart material, MR (magneto-rheological) fluid is dramatically influenced by the external magnetic field and can change from the liquid state to semi-solid state in several milliseconds. In this paper, the effect of different volume of MRF on its shear performance is proposed. A set of testing systems, including the plate-on-plate MRF shearing test rig, is built up to measure the relationship between the produced shear torque and the added volume of MRF in different current. The variation of magnetic flux density in the shear gap is measured by teslameter and simulated before and after MRF is added. The results validate the effect of volume on the shear torque experimentally.