Performance of a Magnetorheological Hydraulic Power Actuation System

Abstract

The performance of a magnetorheological (MR) hydraulic power system is analytically and experimentally assessed. Four MR valves are implemented as a Wheatstone bridge hydraulic power circuit to drive a hydraulic actuator using a gear pump. The compact hydraulic power actuation system is a Wheatstone bridge network driving a conventional hydraulic actuator. A key advantage of using MR valves in hydraulic actuation systems is that the valves have no moving parts. This reduces complexity and enhances durability compared to conventional mechanical valves. In such a system, an MR fluid is used as the hydraulic fluid. A constant volume pump is used to pressurize the MR fluid. If a change in direction is required, the flow through each of the valves in the Wheatstone bridge can be controlled smoothly via changing the applied magnetic field. A magnetic field analysis is conducted to design a high-efficiency compact MR valve. The behavior and performance of the MR valve is expressed in terms of nondimensional parameters. The performance of the hydraulic actuator system with a Wheatstone bridge network of MR valves is derived using three different constitutive models of the MR fluid: an idealized model (infinite yield stress), a Bingham plastic model, and a biviscous model. The analytical system efficiency in each case is compared to experiment, and departures from ideal behavior, that is, a valve with infinite blocking pressure, are recognized.