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Author: search.filters.author.Kumar, H.Subject: search.filters.subject.Shear stress

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    Evaluation of optimal parameters of MR fluids for damper application using particle swarm and response surface optimisation
    (Springer Verlag service@springer.de, 2017) Gurubasavaraju, T.M.; Kumar, H.; Mahalingam, A.
    The controllable rheological properties of MR fluid exhibit viscoelastic properties within pre-yield, which are essential for the characterization of MR dampers for the isolation of vibration. In the present work, using particle swarm optimisation (PSO), it is identified that the proportion of MR fluid constituents, fluid gap and current are the parameters which influence majorly on the rheological properties and damping effect of MR damper. Initially, rheological properties of the prepared MR fluid samples are determined using rotational plate–plate type rheometer with the magnetorheological device cell attachment by keeping three levels of gap between the parallel plates. Three different proportions of MR fluid are prepared based on the volume fraction of carbonyl iron particle, i.e., 25, 30 and 35% in the silicone carrier fluid along with 1% of lithium-based grease as stabiliser. The objective function of this optimisation problem is to maximise the shear stress and damping force of the MR damper. The design of experiment (DOE) is employed to obtain the various combinations of parameters and their respective responses. The interaction of the regression model obtained from the DOE is used in PSO to evaluate the optimal parameters. The results indicated that the MR fluid with the particle concentration of 31% is the optimal proportion for MR damper application. © 2017, The Brazilian Society of Mechanical Sciences and Engineering.
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    Performance analysis of a semi-active suspension system using coupled CFD-FEA based non-parametric modeling of low capacity shear mode monotube MR damper
    (SAGE Publications Ltd, 2019) Gurubasavaraju, G.; Kumar, H.; Mahalingam, A.
    In this work, an approach for formulation of a non-parametric-based polynomial representative model of magnetorheological damper through coupled computational fluid dynamics and finite element analysis is presented. Using this, the performance of a quarter car suspension subjected to random road excitation is estimated. Initially, prepared MR fluid is characterized to obtain a relationship between the field-dependent shear stress and magnetic flux density. The amount of magnetic flux induced in the shear gap of magnetorheological damper is computed using finite element analysis. The computed magnetic field is used in the computational fluid dynamic analysis to calculate the maximum force induced under specified frequency, displacement and applied current using ANSYS CFX software. Experiments have been conducted to verify the credibility of the results obtained from computational analysis, and a comparative study has been made. From the comparison, it was found that a good agreement exists between experimental and computed results. Furthermore, the influence of fluid flow gap length and frequency on the induced force of the damper is investigated using the computational methods (finite element analysis and computational fluid dynamic) for various values. This proposed approach would serve in the preliminary design for estimation of magnetorheological damper dynamic performance in semi-active suspensions computationally prior to experimental analysis. © IMechE 2018.
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    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.
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    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.
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    Synthesis of magnetorheological fluid and its application in a twin-tube valve mode automotive damper
    (SAGE Publications Ltd info@sagepub.co.uk, 2020) Madhavrao Desai, R.; Acharya, S.; Jamadar, M.-E.-H.; Kumar, H.; Joladarashi, S.; Sekaran, S.C.R.
    The change in rheological properties of smart materials like magnetorheological fluid when brought under the influence of a magnetic field can be utilized to develop magnetorheological devices where the output has to be continuously and quickly varied using electronic control interface. In the present study, magnetorheological fluid is synthesized and used as a smart fluid in a twin-tube magnetorheological damper operating in valve mode. The behavior of the magnetorheological fluid is experimentally characterized in a rheometer and mathematically modeled using Herschel–Bulkley model. The parameters of the Herschel–Bulkley model are expressed as polynomial functions of strength of the magnetic field in order to find the shear stress developed by the magnetorheological fluid at any given strength of the magnetic field applied. The magnetorheological damper, which was designed for application in a passenger van, is tested in the damper testing machine. The performance of the damper at different damper velocities and current supplied is studied. The range of values for the parameters of the experimental testing are chosen to emulate the actual conditions of operation in its intended application. Nondimensional analysis is performed, which links magnetorheological fluid rheological properties and geometrical parameters of magnetorheological damper design with the force developed by the damper. Finite element method magnetics is used to find the strength of the magnetic field at the fluid flow gap. Analytical methods are used to calculate the damper force developed due to the field-dependent yield stress and compared with experimental force values. The resulting dynamic range of the magnetorheological damper is also assessed. © The Author(s) 2020.
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    Influence of different fumed silica as thixotropic additive on carbonyl particles magnetorheological fluids for sedimentation effects
    (Elsevier B.V., 2021) Aruna, M.N.; Rahman, M.R.; Joladarashi, S.; Kumar, H.; Bhat Panemangalore, D.B.
    The present work reports the influence of different types of surface area, hydrophobic, and hydrophilic fumed silica mixed in silicone oil as a thixotropic additive on carbonyl particles based magnetorheological fluids (MRFs) were prepared. Scanning electron microscopy analysis confirms the fumed silica particles attached to the surfaces of CIPs. The vibrating sample magnetometer result shows the MRF4 and 5 have a better magnetic saturation value of 30.12 emu/gm and 40.12 emu/gm, respectively. The experimental rheological flow curve behaviours are investigated using the magnetorheometer. The Herschel–Bulkley rheological model is found to be in good agreement with the experimental curves and suggested shear thinning property is observed. The results showed that the hydrophilic silica with larger surface area type presented (i.e.MRF 4 and 5) better magnetorheological fluid characteristics in terms of shear stress, with a high value of dynamic yield stress, and have much-improved sedimentation ratio up to seven days. © 2021 Elsevier B.V.