Magnetic Circuit Analysis and Fluid Flow Modeling of an MR Damper With Enhanced Magnetic Characteristics

A novel design of a magnetorheological (MR) damper is developed, fabricated, modeled, and tested. The design includes some features that enhance the magnetic characteristics of the damper. The iron-cobalt-vanadium "Vacoflux-50" alloy and the "AMT-Smartec+" MR fluid, whose magnetic characteristics have been predicted to enhance the performance of the damper, are used in the new design. Moreover, the location of the MR fluid region in the piston construction has been chosen so that the magnetic field maximizes. To evaluate the impact of the proposed design improvements, an approach to modeling the performance of a previously tested MR damper of a different design, different magnetic material, and different MR fluid has been developed. The approach combines a finite element analysis (FEA) of the magnetic circuit and a nonlinear analytical model of fluid flow. The results of the FE/analytical approach have been validated using the available published results of the same damper. Hence, the approach has been used to predict the performance of the same damper due to the use of the proposed design improvements. The FE/analytical approach accounts for the nonlinear characteristics caused by the magnetic saturation of materials and the effects of fluid compressibility and aeration in the damper. It has been found that the implementation of the proposed design features leads to a remarkable increase in the magnetic field and the fluid yield stress. Also, the inclusion of the nonlinear magnetic and fluid flow characteristics have been found to affect the magnetic field distribution and the fluid yield stress greatly.