Electromagnetical and flow analysis of a magneto-rheological fluid damper, and comparison of results with experiments

Keywords: Magneto?rheological fluids and dampers, Bingham plastic model In the present study, after introducing the magneto?rheological (MR) fluids and MR fluid dampers, electromagnetic analysis of an MR damper is done in computer environment and its operational behavior is predicted by using quasi?static flow analysis. Magneto?rheological fluids are suspensions consisting of a special carrier liquid in which micron?sized iron particles exist. These fluids act like a non?Newtonian fluid when they are subjected to a magnetic field, and their behavior under the magnetic field can be properly described by either Bingham plastic model, for which the shearing stress is defined as ? =? y +?? ? , or Herschel?Bulkley constitutive model with n y ? =? +K? ? , where y ? is the yield stress of the fluid, ? ? is the deformation rate, and K and n are the fluid indexes. In this study, the flow analysis is done based on Bingham plastic model and it is shown that this analysis can be straightforwardly extended to Herschel?Bulkley model. The resulting non?linear system of equations is then solved in order to predict the damping force of the damper corresponding to any piston velocity. The protoyped damper is operated for a period of time in order to reduce the seal drag between contacting mechanical components of the damper to a setady?state level on an operating unit. Then the tests of the damper are conducted at different current and velocity stages ranging from 0 to 2 A and 0 to 2 m/s, respectively on a standart test unit. Finally, theoretical results are compared with the experimental values and it is observed that there is a good agreement between the results.