Double adjustable shock absorbers utilising electrorheological and magnetorheological fluids

Double adjustable shock absorbers allow for independent adjustment of the yield force and post-yield damping in the force versus velocity response. To emulate the performance of a conventional double adjustable shock absorber, an electrorheological (ER) and magnetorheological (MR) automotive shock absorber were designed and fabricated at the University of Maryland. For the ER shock absorber, an applied electric field between two tubular electrodes, located in the piston head, increases the force required for a given piston rod velocity. For the MR shock absorber, an applied magnetic field between the core and flux return increases the force required for a given piston rod velocity. For each shock absorber, two different shaped gaps meet the controllable performance requirements of a double adjustable shock absorber. A uniform gap allows for control of the yield force of the shock absorber, while a nonuniform gap allows for control of the post-yield damping. Force measurements from sinusoidal displacement cycles, recorded on a mechanical damper dynamometer, validate the performance of uniform and non-uniform gaps for adjustment of the yield force and post-yield damping, respectively.