Response time of magnetorheological fluids and magnetorheological valves under various flow conditions

Abstract

In this study, the response times of magnetorheological fluids and magnetorheological fluid valves are studied under various flow configurations. Two types of valving geometries, annular flow and radial flow, are considered in the magnetorheological fluid valve designs. The transient pressure responses of magnetorheological fluid valves are evaluated using a diaphragm pump with a constant volume flow rate. The performance of each magnetorheological valve is characterized using a voltage step input as well as a current step input while recording the activation electric voltage/current, magnetic flux density, and pressure drop as a function of time. The variation of the response time of the magnetorheological valves under constant volume flow rate is experimentally investigated. The Maxwell model with a time constant is employed to describe the field-induced pressure behavior of magnetorheological fluid under a steady flow. The results demonstrate that the pressure response times of the magnetorheological fluid and the magnetorheological valves depend on the designs of the electric parameters and the valve geometry. Magnetorheological valves with annular flow geometry have a slower falling response time compared to their rising response time. Magnetorheological valves with radial flow geometry demonstrate faster pressure response times both in rising and in falling states.

Geometry optimization of a magnetorheological clutch operated by coils

“…In the absence of magnetic field, the ferromagnetic particles are randomly dispersed, while if the fluid is crossed by magnetic field, the ferromagnetic particles align themselves along the magnetic field and confer to the MRF a higher shear strength. As stated by suppliers, 3 the time needed to change the particles' orientation upon the application, or the removal, of the magnetic field is less than 5 ms, as confirmed also in Wereley, 4 while some studies regarding real MRF devices assess that the response time is strongly variable in the range 0.01-1.2 s. 5,6 Even though the first MRFs applications date back to the late 1940s to early 1950s, when the first magnetorheological clutches operated by coils were designed and patented by Rabinow, 7,8 the research activity grew up recently, [9][10][11] thanks to the availability of commercial MRFs and to the spread of Finite Element (FE) software, which can accurately compute the magnetic field distribution in complex geometries.…”

Electrical Properties of Magnetoactive Boron‐Organo‐Silicon Oxide Polymers

“…Conventional MAP demonstrate a similar, though far less dramatic reduction in electrical resistance for an applied magnetic field . Although the magnetic reaction for magnetorheological fluids takes place within 20 ms, the mechanical reaction can be twice this . Magnetoactive polymers are magnetoelastic so the change can take up to several seconds .…”

Magnetic Circuit Analysis and Fluid Flow Modeling of an MR Damper With Enhanced Magnetic Characteristics

“…4. This coil configuration, Configuration (A), is adopted, for example in [22]. However, it is different from the coil configuration presented in [16,23], Configuration (B), in which the current in the coils flow in opposite direction.…”