Abstract
Magnetorheological (MR) fluids can be used in a variety of smart semiactive systems. The MR damper shows an especially great potential to mitigate environmentally induced vibration and shocks. Another aspect of MR fluids is the construction of MR valve networks in conjunction with a hydraulic pump resulting in a fully active actuator. These devices are simple, have few moving parts, and can be easily miniaturized to provide a compact, high energy density pressure source. The present study describes a prototype MR-piezo hybrid actuator that combines the piezopump and MR valve actuator concepts, resulting in a self-contained hydraulic actuation device without active electromechanical valves. Durability and miniaturization of the hybrid device are major advantages due to its low part count and few moving parts. An additional advantage is the ability to use the MR valve network in the actuator to achieve controllable damping. The design, construction, and testing of a prototype MR-piezo hybrid actuator is described. The performance and efficiency of the device is derived using ideal, Bingham plastic and biviscous representations of MR valve behavior, and is evaluated with experimental measurements. This study seeks to provide a design tool to develop an actuator for a specific application.