Development on 2DOF-type and Rotary-type shock absorber damper using MRF and their efficiencies

Two types of dampers were developed: 2DOF (degree of freedom )-type and Rotary-type, to protect the patient lying on the bed in ambulance from shock due to sudden break. Both consists of a number of plates with slits and Magnetic Rheological Fluid (MRF) filled in the damper, so that magnetic field generated by permanent magnets and controllable electric field will freeze MRF and shear force can be gained. The damping mechanism is based on the fail-safe characteristic of the MRF damper that in zero-field (current off-state), the damper will be in passive mode operation and similar to the passive shock absorber. This paper presents a preliminary work of development of semi-active damper and investigation on the efficiency of using MRF as damper material in both types. Experimental tests were carried out and it is shown that both dampers suppressed the shock significantly while Rotary-type has a better performance than 2DOF-type.