Magnetorheological fluid

About: Magnetorheological fluid is a research topic. Over the lifetime, 8538 publications have been published within this topic receiving 131502 citations. The topic is also known as: MRF & MR fluid.

Magnetic field dependent electro-conductivity of the graphite doped magnetorheological plastomers

Abstract: In this work we reported a novel graphite doped conductive magnetorheological plastomer (GMRP) with magnetic field dependent electro-conductivity. The conductivity of the GMRPs increased by increasing the content of the graphite particles, while it decreased with the graphite size. When the graphite content reached 15 wt%, the conductivity of GMRPs is approximately 10 000 times higher than the non-doped MRP. Because the iron particles in the GMRPs were magnetic, the conductivity of the GMRPs was magnetically sensitive. Upon applying a 780 mT magnetic field, the electric conductivity could increase about 1000 times larger than the one under zero magnetic field. A particle–particle resistance model was developed to investigate the influence of the magnetic field and graphite doping on the conductivity, and the fitting curve matched the experimental results very well. Finally, a magnetically controllable on–off switch based on GMRPs was proposed and its working mechanism was discussed.

Compact MR-brake with serpentine flux path for haptics applications

Abstract: This research explores a new approach to shape the magnetic flux path in a MR brake. Magnetically conductive and non-conductive elements were stacked to weave the magnetic flux through the rotor and the outer shell of the brake. This approach enabled design of a more compact and powerful MR brake. In addition, a ferro-fluidic sealing technique was developed to prevent the fluid from leaking and to reduce off-state friction. Experimental results showed that, when compared to a commercial MR brake, our 33% smaller prototype MR-brake could generate 2.7 times more torque (10.9 Nm). A 1-DOF haptic interface employing the brake enabled crisp virtual wall collision simulations. Significant reduction in the off-state torque was obtained by applying a reverse current pulse to collapse a residual magnetic field in the brake.

Magnetorheological polymer gels

Abstract: Magnetorheological materials are provided comprising magnetic particles, a polymeric gel and a carrier material. The polymerization of the gel is preferentially accomplished in the presence of the magnetic particles and the carrier material. Magnetorheological materials are provided having a selected off-state viscosity and a selected on-state apparent viscosity. The method of preparing these magnetorheological materials is also provided. The carrier material, the polymeric gel and the magnetic particles are selected so that the resulting magnetorheological material has the desired off-state viscosity and on-state apparent viscosity. These materials have good dispersion characteristics, reduced settling, superior off-state viscosity and superior apparent viscosity in the presence of a magnetic field.

A New Magneto-rheological Fluid Damper for High-mobility Multi-purpose Wheeled Vehicle (HMMWV)

Abstract: This study focuses on the design, development, and testing of a new magnetorheological fluid (MRF) damper for high-mobility multi-purpose wheeled vehicle (HMMWV). The new damper is designed to provide controllability while keeping the same geometrical dimensions as the original equipment manufacturer (OEM) damper. To design a fail-safe MRF damper, MRF behavior is simulated using the Bingham Plastic model, and the magnetic field distribution is obtained by a three-dimensional electromagnetic finite element analysis. A fail-safe MRF damper is referred to one which retains a minimum damping capacity comparable to that of OEM damper in the event of a power supply or electronic system failure. The proposed MRF damper is designed to achieve non-symmetrical force characteristics with different force responses at rebound and compression phases. Theoretical predictions and experimental results are presented for the force—displacement and force— velocity behaviors of the damper under different input motions, variou...

Application of smart passive damping system using MR damper to highway bridge structure

Abstract: Magnetorheological (i.e., MR) dampers are one of the most prospective semiactive control devices for civil engineering applications to earthquake hazard mitigation, because they have many advantages such as small power requirement, reliability, and low price to manufacture. A smart passive system based on an MR damper system without including a power supply, controller, and sensors consists of an MR damper and an electromagnetic induction (i.e., EMI) system that uses a permanent magnet and a coil. The electromotive force induced by movement of a structure can control MR damper effectively without any external power supply and control algorithm. This smart passive control system is implemented to verify the effectiveness for seismic protection of benchmark structural control problem for the seismically excited highway bridge, which is based on the newly constructed 91/5 highway over-crossing in Southern California. The results of the numerical simulations show that the presented control system can be beneficial in reducing seismic responses of benchmark bridge structure.