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.

Simulation of magneto-induced rearrangeable microstructures of magnetorheological plastomers

Abstract: Magneto-induced microscopic particulate structures of magnetorheological plastomers (MRP) are investigated using particle-level dynamics simulation, as this is a basis for studying the macroscopic physical or mechanical properties of MRP. In the simulation, a modified magnetic dipolar interaction force model is proposed to describe the magnetic interaction of two close magnetized iron particles. Other microscopic analytical models of particle–particle and particle–matrix interactions are also constructed. The simulation results show that chain-like and column-like particulate structures are formed when MRP is placed into a steady uniform magnetic field. When MRP is subjected to a stepwise in-plane rotating magnetic field, the microstructure rearranges to form a layered structure parallel to the rotation plane. Moreover, some other patterns or complex magneto-induced rearrangeable microstructures can be achieved by spatially changing the external magnetic field. With the evolution of the microscopic particulate structure in every changing step of the external magnetic field, the microstructure dependent magnetic potential energy and stress state vary sharply at the beginning and then approach respective stable values gradually.

Magnetic-field Sensitive Gels with Wide Modulation of Dynamic Modulus

Abstract: A new class of magnetorheological gel that demonstrates drastic and reversible changes in dynamic modulus without using strong magnetic fields was obtained. The magnetic gel consists of carrageenan...

Hybrid structural control using magnetorheological dampers for base isolated structures

Abstract: In this paper two nonlinear model based control algorithms have been developed to monitor the magnetorheological (MR) damper voltage. The main advantage of the proposed algorithms is that it is possible to directly monitor the voltage required to control the structural vibration considering the effect of the supplied and commanded voltage dynamics of the damper. The efficiency of the proposed techniques has been shown and compared taking an example of a base isolated three-storey building under a set of seismic excitations. Comparison of the performances with a fuzzy based intelligent control algorithm and a widely used clipped optimal strategy has also been shown.

Effect of Particle Size on Shear Stress of Magnetorheological Fluids

Abstract: Magnetorheological fluids (MRF), known for their variable shear stress contain magnetisable micrometer-sized particles (few micrometer to 200 micrometers) in a nonmagnetic carrier liquid To avoid settling of particles, smaller sized (3-10 micrometers) particles are preferred, while larger sized particles can be used in MR brakes, MR clutches, etc as mechanical stirring action in those mechanisms does not allow particles to settle down Ideally larger sized particles provide higher shear stress compared to smaller sized particles However there is need to explore the effect of particle sizes on the shear stress In the current paper, a comparison of different particle sizes on MR effect has been presented Particle size distributions of iron particles were measured using HORIBA Laser Scattering Particle Size Distribution Analyser The particle size distribution, mean sizes and standard deviations have been presented The nature of particle shapes has been observed using scanning electron microscopy To explore the effect of particle sizes, nine MR fluids containing small, large and mixed sized carbonyl iron particles have been synthesized Three concentrations (9%, 18% and 36% by volume) for each size of particles have been used The shear stresses of those MRF samples have been measured using ANTON PAAR MCR-102 Rheometer With increase in volume fraction of iron particles, the MR fluids synthesized using “mixed sized particles” show better shear stress compared to the MR fluids containing “smaller sized spherical shaped particles” and “larger sized flaked shaped particles” at higher shear rate

Modeling and control of an improved dissipative passive haptic display

Abstract: This work investigates the modeling and control of a new dissipative passive haptic display that uses magnetorheological (MR) brakes as actuators. The device is energetically passive, meaning that it can only remove energy from the system. All motive force must be generated by the user, which guarantees stability of the system and safety of the human operator. A first order system approach is presented as a tool for modeling MR fluid behavior in a low-speed braking device. A simulation was developed that uses the brake model and the equations of motion to predict robot motion based on force input and actuator commands. The accuracy of these models was demonstrated with comparisons to experimental data. Two forms of path following velocity control were successfully implemented and shown to significantly reduce path error in preliminary experiments with human operators.