There is currently a need for compact actuators capable of producing large deflections, large forces, and broad frequency bandwidth. In all existing transducer materials, large force and broadband responses are obtained at the price of small displacements and methods
for transmitting very short transducer element motion to large deformations need to be developed. This paper addresses the development of a hybrid actuator which provides virtually unlimited deflections and large forces through magnetorheological (MR) flow
control and rectification of the resonant mechanical vibrations produced by a magnetostrictive Terfenol-D pump. The device is a self-contained unit which produces large work output concurrently with stiffness and damping control, and is compact and self-locking when unpowered. To increase the output force, hydraulic advantage is created by implementing a driven piston diameter that is larger than the drive piston. Since the pump operates at high speeds in the low kHz range, a fast-acting MR fluid valve is required. The paper presents a four-port MR fluid valve in which the fluid controls its
own flow while carrying the full transducer load. A prototype two-port valve was designed and constructed. Experimental measurements at various pressure levels are presented which demonstrate the new valve concept.