Yasrebi N.

In this paper a finite element analysis of magnetorheological fluid (MR) damper is presented. Electromegnetical and fluid flow analyses have been performed separately. A two dimensional axis-symmetric model was developed for the piston of MR damper. Electromagnetic analysis was performed to calculate magnetic field in fluid gap (region between cylinder and piston of damper).Nonlinear analysis is carried out for electromagnetic analysis (material of piston, cylinder and MR fluid was modeled as nonlinear magnetic materials). Results of electromagnetic analysis have been used to get the yield stress of MR fluid which depends on the strength of magnetic field. Fluid flow was also analyzed in fluid gap. For fluid flow, the fluid was modeled as Bingham fluid with corresponding yield stress obtained from electromagnetic analysis and consequently, pressure drop across piston damper was obtained. By using these results the damping force was calculated and force-velocity graph was plotted. An MR damper was designed and fabricated in Tehran University, UTMR83.Damper standard tests has been performed on this damper and force-velocity and force-displacement graph were then obtained. Model geometry, material properties and other specifications of the finite element model were extracted from UTMR83 model. Finite element results are then compared with the experimental results obtained from UTMR83 tests. Results matched well and showed that the method used for predicting performance of MR dampers is accurate and can be used for design and optimization purposes.