Normal force for static and steady shear mode in magnetorheological fluid

• In the static shear mode, with the magnetic flux density increasing, the normal force will increase to the maximum, and then reduce to a steady value. During the increasing stage, it can be expressed as FN=4667*B2.48 approximately.
• In the steady shear mode, when the magnetic flux density in MR fluid is less than 100 mT, with the increasing of magnetic flux density, the increasing of normal force in MR fluid is not very obvious. Once the magnetic flux density is above 100 mT, there occurs a continuous increasing in normal force dramatically, until the magnetic field tends to saturation, the relationship between the normal force and the magnetic flux density can be expressed as FN=7725*B2.23.
• The experimental results on the dynamic response of normal force show, if the shear plate is stationary, from the magnetic field on to a stable normal force produced, the response time is about 25.11 ms.

This paper presents the normal force phenomena for static and steady shear mode in magnetorheological (MR) fluid. The results of the study show that, in the static mode, with the magnetic flux density increasing, the normal force will increase until the maximum, and then reduce to a steady value, and during the increasing stage, it can be expressed as FN=4667*B2.48 approximately; however, in the steady shear mode, only when the magnetic flux density achieves a certain value, the normal force phenomena will be observed clearly, and with the increasing of magnetic field, the normal force reaches the maximum, and then also decreases to a steady value. Besides, by defining the time parameters of dynamic response, the dynamic response of normal force is studied. If the shear plate is stationary, from the magnetic field on to a stable normal force produced, the response time is about 25.11 ms.