CHARACTERIZATION AND MODELING MAGNETORHEOLOGICAL BY-PASS DAMPER EXPLOITING FLOW THROUGH A POROUS MEDIA

摘要

A magnetorheological (MR) fluid bypass damper exploiting flow through porous media is developed utilizing a valve filled with porous media instead of regular uniform channels to adoptively regulate damping force. The MR damper includes a cylinder containing an MR fluid, a movable piston and a bypass valve. The bypass valve filled with porous media is used to provide a magnetically energizable passageway. A stationary magnetic coil is wrapped around the bypass valve, isolated from the MR fluid and external to the device. The axis of the bypass valve is collinear with the center of the magnetic coil such that the magnetic flux return guide of the coil can be either empty (air) or any high permeability steel material which provides flexibility for damper design. The damper is applied with sinusoidal excitations. Equivalent viscous damping is used to characterize the damper. It is shown that the MR damper exploiting flow through porous media can provide high controllable damping force using a compact damper configuration. To describe the behavior of the MR damper, the flow path in the porous media is considered as a multiple-pipe system. Using quantitative and empirical analysis of the magnetic and rheological properties of MR fluid flowing through the porous media in the bypass valve, the controllable damping performance of the damper is well predicted using the model, and the force-displacement hysteresis behavior of the damper can also be described by the analytical model. The model is validated by the experimental data at different frequencies and applied currents.