Abstract: An MR shock absorber under impact load is investigated. A single-rod long-stroke impact absorber is developed. Based on Bingham model and its structure of MR damper under impact load, a dynamic model of MR damper under impact load is derived, which is composed of annular damping hole’s friction damping force, coulomb damping force, inertia damping force, throttle damping force, structure additional damper force and other friction forces. By applying the least square algorithm, important parameters in the dynamic model are identified. Experimental results confirm the accuracy of the derived and fitted dynamic model. According to its strong nonlinearity, wide frequency range and high peak-value of acceleration characteristics of impact load, an output target tracer using sliding control strategy is designed and simulated on the basis of constructing hardware-in-the-loop platform. The control effects of three control strategies, namely, On-Off strategy, PID strategy and sliding mode control strategy, are compared and analyzed. The results show that the vibration peak value of MR impact absorber under sliding mode control strategy is reduced by 27.33%, and its piston stroke is reduced by 48.75% , thus being the most ideal control effect.

Key words: Dynamic modeling, Impact load, Magnetorheological absorber, Sliding mode control