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.

Neural network modeling and controllers for magnetorheological fluid dampers

Abstract: One of the challenging aspects of utilizing magnetorheological (MR) dampers to achieve high level of performance is the development of accurate models and control algorithms that can take advantages of the unique characteristics of these devices because of their inherent nonlinearity. In this paper, the authors proposed a direct identification and an inverse dynamic modeling method for MR dampers using recurrent neural networks. Based on the above neural network models, a configuration for the MR damper controller is also explored. The command voltage for the MR damper can be obtained through the neural network model according to the desired damping force determined from the system controller. The architectures and the learning methods of the direct and inverse dynamic neural network models for the MR damper are presented, and some simulation results about the MR damper controller are discussed.

Constitutive models of magnetorheological fluids having temperature-dependent prediction parameter

Abstract: This work presents constitutive models of magnetorheological (MR) fluids, which can predict the shear and dynamic yield stress depending on temperature. Two existing models, the Herschel–Bulkley rheological and power law model, which are frequently used in MR fluid research, are adopted and modified to take the temperature into account. A new constitutive model of MR fluids is developed using the extreme learning machine (ELM) method. In this development, among many machine learning approaches, a simple and efficient learning algorithm for a single hidden layer feed-forward neural network (SLFN) is adopted and applied to the rheological model of MR fluids. The temperature, shear rate, and magnetic field are treated as inputs, and the shear stress is taken as an output. After formulating the models associated with experimental coefficients, the two most important properties of MR fluids; the shear and yield stress are predicted and compared with the measured values. The prediction accuracy for the field-dependent rheological properties of MR fluids in several different temperatures is evaluated and compared. It is shown that the ELM model developed in this work provides the best accuracy, followed by two other modified constitutive equations.

Temperature independent magnetorheological materials

Abstract: A magnetorheological material containing a particle component and a carrier fluid or mixture of carrier fluids having a change in viscosity per degree temperature (Δη/ΔT ratio) less than or equal to about 160 centipoise/°C over the temperature range of about 25° C to -40° C The magnetorheological material exhibits a substantial magnetorheological effect and excellent lubricating properties with a minimal variation in mechanical properties with respect to changes in temperature The magnetorheological material is advantageous in that it provides for the design of devices that are smaller, more efficient and consume less power

Viscoelastic Properties of Magnetorheological Elastomers for Damping Applications

Abstract: Magnetorheological elastomers (MRE) have been synthesized on the basis of a silicon compound and a mixture of carbonyl iron particles of sizes 3–5 and 40–80 μm. Their viscoelastic properties have been studied by dynamic shear oscillations of various amplitudes on a stress controlled rheometer. The magnetic response of the obtained materials has been examined in a magnetic field applied perpendicular to the shear plane. It has been shown that under applied magnetic field both the storage G′ and loss G″ moduli became strain-dependent. The values of G′ and G″ decrease with strain, while their ratio (the loss factor), G″/G′, growths with strain. The higher magnetic field is the more pronounced the strain dependence is. At small strain (up to 1%) MRE demonstrate a giant (more than 10 times) increase of the moduli. Some features of hysteretic behavior of MRE under simultaneously applied magnetic field and external mechanical force have been elucidated. Temperature has a negligible effect on viscoelastic properties and stability of the developed MRE. A damper on the basis of MRE has been designed and its properties have been examined.

Study of the behavior of MR fluids in squeeze, torsional and valve modes

Abstract: In order to understand the effectiveness of MR fluids in some applications, such as bearings, this work focuses on the properties of MR fluids under squeeze mode, torsional mode and squeeze combined with torsional mode. A special device was designed and fabricated to perform these experiments, which were carried out on an Instron Multiaxial Testing Machine. The hysteresis loops of the MR fluids were studied for different intensities of electric current, frequency, strain amplitude and angle amplitude. The results showed that the damping force and the area of the hysteresis loop of MR fluids increase with the current and strain amplitude. Changes on the frequency did not influence the stress values significantly, within the range of frequencies used in these experiments. In order to evaluate the performance of a squeeze film damper (SFD), measurements were made using a MR damper manufactured by Lord Corporation (RD1005), which operates in valve mode. The results of the SFD were compared to the ones obtained with the RD1005 damper. The shape of the hysteresis loop curves and the MR effect were found to be different for the squeeze film damper and the RD1005 damper.