Magnetorheological Fluid Based Devices Reported in 2013–2018: Mini-Review and Comment on Structural Configurations

This paper presents a mini-review of magnetorheological (MRF) fluid-based devices (MRF devices in short) including the brake, clutch, damper, and the mount reported from 2013 to 2018. MRF devices are usually designed based on three operating modes of MRF: flow mode, shear mode and squeeze mode. Each mode has its own characteristics for the high performance of application systems. Therefore, numerous design configurations of MRF devices have been proposed by many researchers. In this article, among many different MRF devices such as MRF brake, clutch, damper and MRF mount proposed over the last 6 years are examined in the sense of their structural configuration and operating principles. Certain advantages and demerits of each MRF device are also discussed. In addition, some useful design guidelines of MRF devices, which are absolutely different from developed MRF devices so far, are provided to enhance design simplicity and control performance

Research on deep hole drilling vibration suppression based on magnetorheological fluid damper

Based on the working principle of magnetorheological fluid damping, in this paper, a set of squeezing mode Magneto-rheological Fluid (MRF) dampers is designed for drilling vibration suppression in deep hole machines. Elaborate analysis of the correlativity between the dynamic morphology trajectory of the machined hole surface, the vibration of the drilling tool-shaft, and the theoretical derivation of the damping force, is put forward in accordance with the Bingham model and Euler-Bernoulli beam Equation. Simultaneously, the contrast analysis of the vibration suppression effect is carried out through the drilling experiments with and without an MRF damper. In addition, a series of measurements on the vibration characteristics of the drilling shaft, the drilling tool and the guide surface wear patterns, and the machine hole surface are analyzed, respectively. Both the drilling experiments and theory studies have revealed that the strength of the magnetic field changed with the drill shaft at different levels of vibration. The MRF damper could suppress the vibration with nonlinear characteristics initiatively and instantaneously, by variable damping, which can eventually improve the surface roughness. In addition, according to the phenomenon of tool tipping, the breakage of the guide bars and the machine hole surface deduces the condition of the vibration effect objectively

High-flux magnetorheology at elevated temperatures

Commercial applications of magnetorheological (MR) fluids often require operation at elevated temperatures as a result of surrounding environmental conditions or intense localized viscous heating. Previous experimental investigations of thermal effects on MR fluids have reported significant reductions in the magnetorheological stress with increasing temperature, exceeding the predictions made by considering the thermal variations in the individual physical properties of the fluid and solid constituents of a typical MR fluid. In the low-flux regime, designers of MR fluid actuators can alleviate this thermal reduction in stress by increasing the applied magnetic field strength. However, this is not possible in the high-flux regime because of magnetic saturation, and it becomes necessary to explore and understand the intrinsic limitations of the fluid at elevated temperature. We describe a new magnetorheological fixture, which was designed as an accessory to a commercial torsional shear rheometer, capable of applying magnetic flux densities up to 1 T and controlling the sample temperature up to 150°C. During the design of the instrument, close attention was given to the uniformity of the magnetic field applied to the sample by using numerical simulations. Incorporation of a custom-built magnetic flux sensor which matches the environmental capabilities of the fixture enables in situ measurement of the local magnetic field at each temperature. The numerical results are also validated by spatially resolved measurements of the local magnetic field. Finally, we explore the ability of a shift factor between fluid magnetization and yield strength to describe the measured variation in the MR fluid response at elevated temperatures

High-flux Magnetorheology at Elevated Temperatures

by increasing the applied magnetic field strength. However, because the fluid response to the applied field is limited in the high-flux regime by magnetic saturation, the ability to correct thermorheological changes are limited and it becomes necessary to explore and understand the intrinsic limitations of the fluid at elevated temperature. We describe a new magnetorheological fixture that is designed as a removable accessory to a commercial torsional shear rheometer. Careful consideration of the mechanical, thermal and electromagnetic design constraints enabled us to extend the operating range of the device. The assembled fixture is capable of applying magnetic flux densities up to 1T and controlling 2 the sample temperature up to 150°C. During the design of the instrument, close attention was given to the uniformity of the magnetic field applied to the sample by using finite element simulations. Incorporation of a custom-built magnetic flux sensor which matches the environmental capabilities of the fixture enables in-situ measurement of the local magnetic field at each temperature. The numerical results are also validated by spatially-resolved measurements of the local magnetic field throughout the sample. Finally, we explore the ability of a shift factor between fluid magnetization and yield strength to describe the measured variation in the MR fluid response at elevated temperatures

Vibration, Control and Stability of Dynamical Systems

From Preface: This is the fourteenth time when the conference “Dynamical Systems: Theory and Applications” gathers a numerous group of outstanding scientists and engineers, who deal with widely understood problems of theoretical and applied dynamics. Organization of the conference would not have been possible without a great effort of the staff of the Department of Automation, Biomechanics and Mechatronics. The patronage over the conference has been taken by the Committee of Mechanics of the Polish Academy of Sciences and Ministry of Science and Higher Education of Poland. It is a great pleasure that our invitation has been accepted by recording in the history of our conference number of people, including good colleagues and friends as well as a large group of researchers and scientists, who decided to participate in the conference for the first time. With proud and satisfaction we welcomed over 180 persons from 31 countries all over the world. They decided to share the results of their research and many years experiences in a discipline of dynamical systems by submitting many very interesting papers. This year, the DSTA Conference Proceedings were split into three volumes entitled “Dynamical Systems” with respective subtitles: Vibration, Control and Stability of Dynamical Systems; Mathematical and Numerical Aspects of Dynamical System Analysis and Engineering Dynamics and Life Sciences. Additionally, there will be also published two volumes of Springer Proceedings in Mathematics and Statistics entitled “Dynamical Systems in Theoretical Perspective” and “Dynamical Systems in Applications”

SIRM 2017

This volume contains selected papers presented at the 12th International Conference on vibrations in rotating machines, SIRM, which took place February 15-17, 2017 at the campus of the Graz University of Technology. By all meaningful measures, SIRM was a great success, attracting about 120 participants (ranging from senior colleagues to graduate students) from 14 countries. Latest trends in theoretical research, development, design and machine maintenance have been discussed between machine manufacturers, machine operators and scientific representatives in the field of rotor dynamics. SIRM 2017 included thematic sessions on the following topics: Rotordynamics, Stability, Friction, Monitoring, Electrical Machines, Torsional Vibrations, Blade Vibrations, Balancing, Parametric Excitation, and Bearings. The papers struck an admirable balance between theory, analysis, computation and experiment, thus contributing a richly diverse set of perspectives and methods to the audience of the conference

Magnetorheological fluids for extreme environments : stronger, lighter, hotter

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 270-275).The controllable properties of magnetorheological (MR) fluids offer reliable and efficient actuation means to a number of far-ranging engineering applications. In this thesis we are motivated by the applications of MR fluids in oil & gas exploration and production. These applications also bring about a number of operational requirements for the fluid such as generating large magnetically induced shift in rheological properties with tolerance to elevated temperatures and low fluid density in order to maintain manageable hydrostatic downhole pressures. In this thesis we investigate a number of these fluid design constraints. Firstly, the evolution of the rheological properties of MR fluids over a wide range of magnetic field and temperature was investigated. A magnetorheometry fixture with a unique combination of high-field and high-temperature capability was manufactured. With the experimental measurements and the results from a numerical model of interparticle magnetic interaction, a scaling law was identified between the applied magnetic field and the resulting MR yield stress. The aggregation phenomena and the evolution of fluid microstructure were also investigated in microfluidic geometries with strong particle-wall interactions. The results of this study highlighted design features and operational techniques that can improve the performance of MR fluid valves. Investigation of fluid flow in non-uniform magnetic fields showed that in these regions the motion of the particle phase is governed by a balance between hydrodynamic and magnetophoretic forces. Finally, the flow of MR fluids in spatially-inhomogeneous magnetic and deformation fields was studied. A slit-flow magnetorheometer was manufactured to measure the bulk MR response of the fluid under non-uniform fields. In order to understand the parameters governing these flows and to develop a predictive tool for further investigations, a two-fluid suspension-balance constitutive model was developed which captures the key features of multi-phase flow and fluid anisotropy. The model was numerically implemented using the finite element method and was used to study the transport of MR fluids in spatially-inhomogeneous flows such as those encountered in contraction and expansion channels. This model provides insight into the design and optimization of MR fluid devices that can enhance the magnetically-controlled gain in flow resistance under downhole conditions.by Murat Ocalan.Ph.D

Nanofluid Flow in Porous Media

Studies of fluid flow and heat transfer in a porous medium have been the subject of continuous interest for the past several decades because of the wide range of applications, such as geothermal systems, drying technologies, production of thermal isolators, control of pollutant spread in groundwater, insulation of buildings, solar power collectors, design of nuclear reactors, and compact heat exchangers, etc. There are several models for simulating porous media such as the Darcy model, Non-Darcy model, and non-equilibrium model. In porous media applications, such as the environmental impact of buried nuclear heat-generating waste, chemical reactors, thermal energy transport/storage systems, the cooling of electronic devices, etc., a temperature discrepancy between the solid matrix and the saturating fluid has been observed and recognized