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.

A high performance magnetorheological valve with a meandering flow path

Abstract: The huge developments in the field of magnetorheological (MR) fluid-based devices will have a great influence on the future of mechatronic applications due to the ease of interfacing between electronic controls and the mechanical components that they provide Among various MR fluid-based devices, an MR valve would be particularly significant for the development of other devices, if it could be successfully achieved One of the most challenging obstacles to MR valve development is the difficulty of achieving device miniaturization while, at the same time, improving the achievable performance This study demonstrates a novel design for an MR valve, using the meandering flow path approach in order to increase the effective area so that the MR fluid can be regulated within a small-sized valve The meandering flow path is formed by combining multiple annular, radial and orifice flow channels In order to analyze the valve performance, a mathematical model of the proposed MR valve is derived and combined with numerical simulation using the finite element method, with the intention of predicting the achievable pressure drop that can be generated by the valve The predicted MR valve performances are then experimentally evaluated using an oscillation-disturbed bypass hydraulic cylinder The simulation results show that the proposed MR valve design could yield substantial pressure drop improvement, which is confirmed by the experiment

Method and apparatus for chemical polishing using field responsive materials

Abstract: A process for, and apparatus for, Chemically-Mechanically Polishing (CMP) a semiconductor wafer with a slurry including ElectroRheological (ER) and/or MagnetoRheological (MR) fluids. The combination of the materials and an electric field provides inherent tuning of polishing rates, locally and globally, and improves flatness and uniformity, as well as minimizing recession and erosion.

A review of design and modeling of magnetorheological valve

Abstract: Following recent rapid development of researches in utilizing Magnetorheological (MR) fluid, a smart material that can be magnetically controlled to change its apparent viscosity instantaneously, a lot of applications have been established to exploit the benefits and advantages of using the MR fluid. One of the most important applications for MR fluid in devices is the MR valve, where it uses the popular flow or valve mode among the available working modes for MR fluid. As such, MR valve is widely applied in a lot of hydraulic actuation and vibration reduction devices, among them are dampers, actuators and shock absorbers. This paper presents a review on MR valve, discusses on several design configurations and the mathematical modeling for the MR valve. Therefore, this review paper classifies the MR valve based on the coil configuration and geometrical arrangement of the valve, and focusing on four different mathematical models for MR valve: Bingham plastic, Herschel–Bulkley, bi-viscous and Herschel–Bulkley with pre-yield viscosity (HBPV) models for calculating yield stress and pressure drop in the MR valve. Design challenges and opportunities for application of MR fluid and MR valve are also highlighted in this review. Hopefully, this review paper can provide basic knowledge on design and modeling of MR valve, complementing other reviews on MR fluid, its applications and technologies.

Carbon Nanotube–Magnetite Composites, With Applications to Developing Unique Magnetorheological Fluids

Abstract: The development of carbon nanotube (CNT) based technology is limited in part by the lack of effective bulk methods for precisely manipulating and aligning nanotubes at the very fine scale Moreover, the innate hydrophobic and inert nature of the CNT surface limits their compatibility with aqueous systems and flexibility for surface chemistry functionalization This paper assesses the variety of methods developed to couple magnetically susceptible components such as ferromagnetic material with CNTs in order to overcome these limitations In addition to reviewing the past 16 years of relevant literature, our own methods for noncovalent surface coating of CNT's with magnetite nanoparticles are described The application of such composites is then explored within the framework of a magnetorheological (MR) fluid It is found that the addition of magnetite nanoparticles to a MR fluid enriches the available MR response, resulting, in some cases, in an increased sedimentation stability, larger saturation critical stresses, and faster response to time varying magnetic fields Finally, our own composite based MR fluid is discussed, and shown to possess a field dependent response that is a hybrid between that observed in ferrofluids and conventional MR fluids