Abstract: Impact test on a self-designed long-stroke MR damper is done and the dynamic performance of MR damper is examined. By curve fitting the experimental data with nonlinear least square method, it is shown that the steady flow equations for parallel plates based on the non-linear Herschel-Bulkley fluid model are able to accurately describe the dynamic behavior of the MR damper in the falling stage of the recoil velocities under impact load. Since the mathematical expression of the above model is complicated with different forms in high and low recoil velocities respectively, a simplified dynamic model with uniform mathematical expression is proposed, in which the hyperbolic tangent function is used to make the force-velocity curve smooth at low velocities, and parameters in this model are identified. Using the proposed MR damper dynamic model, impact simulation platform of MR damper is established in Matlab/Simulink, and numerical simulation of this impact test is done. It is shown that the simulation curves fit well with the experimental ones, and the validity of the simplified model of MR damper is verified.

Key words: Impact load, Magneto-rheological dampers, Mathematical modeling, Parameter identifications