Faculty Publications
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Item Influence of additives on the synthesis of carbonyl iron suspension on rheological and sedimentation properties of magnetorheological (MR) fluids(Institute of Physics Publishing helen.craven@iop.org, 2019) Aruna, M.N.; Rahman, M.R.; Joladarashi, S.; Kumar, H.Magnetorheological (MR) fluid is one of the major constituent element in structural suspensions and damping characteristic in automobile applications. The major drawback is sedimentation in MR fluids, in the present study an attempt has been done to address the sedimentation issue. The synthesis and characterization of MR fluid in combination with clay and additives leads to improvement in sedimentation rate. The four different types of MR fluid were prepared in combination with clay, friction reducing agent and poly-alpha-olefin (PAO) oil naming as MRFp-1, 2, 3 and 4 as tabulated in table 1. The cost effective MRFp-3 shows better result compared to commercially available MR fluid with respect to off/on state shear stress, viscosity. It is also observed that in-house prepared MRFp-3 has better sedimentation than commercially available (LORD-132DG) up to 700 h. © 2019 IOP Publishing Ltd.Item Determination of optimal magnetorheological fluid particle loading and size for shear mode monotube damper(Springer Verlag service@springer.de, 2019) Acharya, S.; Saini, R.S.S.; Kumar, H.Magnetorheological (MR) fluids belong to a class of controllable fluids, and the composition and concentration of its components govern its magnetorheological properties. In this study, an optimum particle loading (or mass fraction) and size of iron particles in MR fluid for use in a shear mode monotube MR damper were determined based on the damping force and off-state viscosity of synthesized MR fluid samples. Initially, the morphological and magnetic properties of carbonyl iron particles were characterized. Six MR fluid samples were prepared composed of combination of three different particle loadings and two sizes of iron particles. Magnetorheological tests were conducted on these samples to determine the flow curves at off-state and on-state magnetic field conditions. Herschel–Bulkley model was used for mathematical representation of flow curves at different magnetic fields and to determine their dynamic yield stress. Further, a shear mode monotube MR damper with accumulator was designed by using optimization technique for desired dynamic range and damping force. Magnetostatic analysis was performed to determine the magnetic field strength generated in the shear gap at different currents. The damping force was calculated for synthesized MR fluids based on their dynamic yield stress corresponding to the magnetic field strength in the shear gap. Analysis of variance was performed to analyse the significance of independent factors on the damping force and off-state viscosity of MRF. The optimal particle loading and size which yielded maximum damping force with minimum off-state viscosity were determined using a multi-objective genetic algorithm. © 2019, The Brazilian Society of Mechanical Sciences and Engineering.Item Investigation of sedimentation, rheological, and damping force characteristics of carbonyl iron magnetorheological fluid with/without additives(Springer, 2020) Aruna, M.N.; Rahman, M.R.; Joladarashi, S.; Kumar, H.In the present study, the magnetorheological fluid (MRF) samples are prepared using pure carbonyl iron particles (CIPs), CIPs/Claytone APA/Molyvan 855 additive, and friction reducer dispersed in poly-alpha-olefin oil. The scanning electron microscopy reveals that the Claytone additive morphology looks like a surface abundant in small folds, which connect the gaps between the spherical pure CIPs and prevent sedimentation in the MRF. The magnetic saturation properties are investigated through the vibrating sample magnetometer. The pure CIPs MRF shows (Ms) value as 146.12 emu/g, and the CIPs/Claytone APA/Molyvan indicates (Ms) as 55.12 emu/g. The magnetorheological flow curves, such as shear stress and viscosity as a function of shear rate, are investigated for the MRF samples through the magnetorheometer. The sedimentation analysis of the MRF is observed by visual inspection and shows that the CIPs/Claytone APA/Molyvan improved the sedimentation rate than the pure CIPs MRF. Finally, the experimental characterization of the prototype monotube MR damper is carried out using the hydraulic dynamic testing machine at 1.5 Hz frequency for damper peak–peak displacement length of ± 5 mm at three intervals of 0 h, 24 h, and 72 h in damper to know the effect on damping force for the prepared MRF samples against the sedimentation rate. © 2020, The Brazilian Society of Mechanical Sciences and Engineering.Item Characterization of an in-house prepared magnetorheological fluid and vibrational behavior of composite sandwich beam with magnetorheological fluid core(Sharif University of Technology, 2023) Nagiredla, S.; Joladarashi, S.; Kumar, H.In this research work, two different compositions of MR fluid samples with 24 and 30 percentage (%) volume fraction of carbonyl iron (CI) particles are prepared. Prepared MR fluid (MRF) samples contain carbonyl iron particles as a dispersive medium, silicone oil as a carrier fluid, and white lithium grease as an anti-settling agent. Influence of oscillating driving frequency, strain amplitude, magnetic field, and the percentage of CI particle on the rheological properties of the MR fluid samples are presented. Storage modulus and loss factor equations are estimated from the rheometry results using a linear regression method. The properties of MR fluid samples are taken to design and model the sandwich beams using ANSYS ACP software, where carbon epoxy composite material is used as the face layer and MR fluid as the core material. Modal, harmonic, and transient analysis studies have been conducted on all the modelled sandwich beams. Influence of MR fluid core material thickness, face layer thickness, CI particle volume percentage in the prepared MR fluid sample, and magnetic field on the vibrational response of the sandwich beams have been presented. Carbon-epoxy composites with an in-house made MRF sandwich beam has shown some significant results in the vibrational response. © 2023 Sharif University of Technology. All rights reserved.Item Synthesis, characterization and selection of optimal constituents of magnetorheological fluid for damper application(National Institute of Science Communication and Policy Research, 2025) Acharya, S.; Puneet, N.P.; Desai, R.M.; Sundaram, V.; Kumar, H.Magnetorheological (MR) dampers are a category of energy dissipating devices that employ magnetorheological fluids which undergoes drastic change in its behaviour under the presence of magnetic stimulus. The damping characteristics of an MR damper predominantly depends on the dimensions of damper and on the constituents of MR fluid (MRF). In this work, an optimal MRF composition suitable for a monotube MR damper has been selected from six prepared MRF based on optimization. Initially, MR damper piston dimensions have been obtained by means of optimization. The damper has been fabricated and filled with commercial MRF 132DG™ fluid (Lord Corporation) and its performance has been tested. The experimental results have been validated with computational results. In the next part of the study, MRF samples composed of three particle weight fractions of fine and coarse sized iron particles have been synthesized and the rheological properties have been measured and compared with those of commercial MR fluid. The force-displacement characteristics of damper employing synthesized MRF have been determined with and without application of current to damper coil. Finally, by means of Multi-Objective Genetic Algorithm, optimum iron particle size and weight fraction have been selected from the pareto front solutions. © 2025, National Institute of Science Communication and Policy Research. All rights reserved.