Optimal design of MR shock absorber and application to vehicle suspension

Abstract

This paper presents an optimal design of a magnetorheological (MR) shock absorber basedon finite element analysis. The MR shock absorber is constrained in a specific volume andthe optimization problem identifies geometric dimensions of the shock absorber thatminimize a multi-objective function. The objective function is proposed by considering thedamping force, dynamic range and the inductive time constant of the shock absorber. Afterdescribing the configuration of the MR shock absorber, a quasi-static modeling of the shockabsorber is performed based on the Bingham model of an MR fluid. The initial geometricdimensions of the shock absorber are then determined based on the assumption of constantmagnetic flux density throughout the magnetic circuit. The objective function of theoptimization problem is derived based on the solution of the initial shock absorber. Anoptimization procedure using a golden-section algorithm and a local quadratic fittingtechnique is constructed via a commercial finite element method parametric designlanguage. Using the developed optimization tool, optimal solutions of the MRshock absorber, which is constrained in a specific cylindrical volume defined byits radius and height, are determined. Subsequently, a quarter-car suspensionmodel with the optimized MR shock absorber is formulated and the vibrationcontrol performance of the suspension is evaluated under bump and sinusoidal roadconditions.