Magnetorheological (MR) materials are classified as smart materials due to their responsiveness to external magnetic stimuli. Intensive research on MR materials has led to broad applications in several potential fields. A solid carrier matrix state called MR elastomer with its exceptional magnetic responsive feature is obtained by merging magnetizable particles within an elastomeric polymer. This integration results in outstanding characteristics on the rheological performances. Special prominence is given to the understanding of the base materials and fabrication as well as the functional behavior through various characterization methods. Broad applications of MREs are also explored to provide a profound market picture and to motivate researchers to develop novel technology.

In recent years, there has been major interest in the exposure to physical therapy during rehabilitation. Several publications have demonstrated its usefulness in clinical/medical and human machine interface (HMI) applications. An automated system will guide the user to perform the training during rehabilitation independently. Advances in engineering have extended electromyography (EMG) beyond the traditional diagnostic applications to also include applications in diverse areas such as movement analysis. This paper gives an overview of the numerous methods available to recognize motion patterns of EMG signals for both isotonic and isometric contractions. Various signal analysis methods are compared by illustrating their applicability in real-time settings. This paper will be of interest to researchers who would like to select the most appropriate methodology in classifying motion patterns, especially during different types of contractions. For feature extraction, the probability density function (PDF) of EMG signals will be the main interest of this study. Following that, a brief explanation of the different methods for pre-processing, feature extraction and classifying EMG signals will be compared in terms of their performance. The crux of this paper is to review the most recent developments and research studies related to the issues mentioned above.

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This paper presents dynamic viscoelastic properties of magnetorheological (MR) grease under variation of magnetic fields and magnetic particle fractions. The tests to discern the fielddependent properties are undertaken using both rotational and oscillatory shear rheometers. As a first step, the MR grease is developed by dispersing the carbonyl iron (CI) particles into grease medium with a mechanical stirrer. Experimental data are obtained by changing the magnetic field from 0 to 0.7 T at room temperature of 25 °C. It is found that a strong Payne effect limits the linear viscoelastic region of MR grease at strains above 0.1%. The results exhibit a high dynamic yield stress which is equivalent to Bingham plastic rheological model, and show relatively good MR effect at high shear rate of 2000 s −1 . In addition, high dispersion of the magnetic particles and good thermal properties are proven. The results presented in this work directly indicate that MR grease is a smart material candidate that could be widely applicable to various fields including vibration control.

Abstract. In a magnetorheological (MR) fluid, the rheological properties can be changed in a controlled way, the changes being reversible and dependent on the strength of a magnetic field. The fluids have potentially beneficial applications when placed in various geometrical arrangements. The squeeze mode is a geometric arrangement where two flat parallel solid surfaces, facing each other, are pushed towards each other by an external force, operating at right angles to the surfaces. The liquid initially in the gap between them is free to move away from this increasingly small gap, and it does so by flowing parallel to the surfaces, and collecting in a region where it is no longer in the gap between them. The performance of an MR fluid in compression (squeeze) mode has been studied with the magnetic field being generated by a coil carrying different magnitudes of DC electrical current. A test rig was designed to perform this operation with the flat surfaces being horizontal and being pushed together in a vertical direction and the liquid being forced to move in all directions in a horizontal plane. The rig operated by decreasing the size of the gap at a constant rate. For each trial the current in the coil was kept constant and the instantaneous compressive force was recorded. When plotting compressive stress against compressive strain for each trial, the slope of the curve was found to be larger in general when the current was larger. This was an expected result; however the behaviour is more complicated than this. For a significant range of values of the compressive strain, the slope falls to zero, so that the compressive stress shows no increase during this period, while the compressive strain continues