Papers by Author: Ahmed Issa

Abstract: This paper presents experimental investigations of three MR fluid types under the influence of several factors in tension loading mode. One MR fluid was water-based, MRF-241ES, while the other two were both hydro-carbon based, MRF-132DG and MRF-122-2ED. The magnetic properties of the MR fluids varied significantly due to a higher particle density in the water-based MR fluid compared to the hydrocarbon-based MR fluids. Tension as a squeeze mode, is as an operational mode where two flat parallel surfaces, standing opposite to each other, are pulled apart from each other by an external force, acting along the path of the magnetic flux lines. The experiments were performed in a vertical direction in the environment of a DC magnetic field. Stress-strain curves of the MR fluids under tension showed similar characteristics despite the fact that different types of the carrier fluids were used. The results revealed that the magnitude of the stress, for a given strain value, depended on the applied current and the initial gap size. It was found that, for higher applied currents and smaller initial gap sizes, there were larger stress values. However, the tensile speed had no significant effect on the stress-strain curves of MR fluids.

Abstract: In this paper, the behaviours of three types of MR fluids under quasi-static loadings in tension mode were investigated. One type of water-based and two types of hydrocarbon-based MR fluids were activated by a magnetic field generated by a coil using a constant value of DC electrical current. Experimental results in terms of stress-strain relationships showed that the MR fluids had distinct unique behaviours during the tension process. A high ratio of solid particles to carrier liquid in the MR fluid is an indication of high magnetic properties. The water-based MR fluid had a relatively large solid-to-liquid ratio. At a given applied current, a significant increase in tensile stress was obtained in this fluid type. On the other hand, the hydrocarbon-based MR fluids had relatively lower solid to liquid ratios, whereby, less increases in tensile stress were obtained. The behaviours of MR fluids were dependent on the relative movement between the solid magnetic particles and the carrier fluid. A complication occurs because, in the presence of a magnetic field, there will be a tendency of the carrier fluid to stick with the magnetic particle