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Author: search.filters.author.Joladarashi, S.Subject: search.filters.subject.Silicones

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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.
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    Rheological Properties of the In-house Prepared Magneto-rheological Fluid in the Pre-yield Region
    (Materials and Energy Research Center, 2022) Nagiredla, S.; Joladarashi, S.; Kumar, H.
    The essence of the present work is to study the rheological properties of the in-house prepared magnetorheological (MR) fluids in the pre-yield region since the rheological properties play a vital role in better understanding of vibration damping capabilities of MR fluids. In the present work, two different compositions of MR fluid samples were prepared with 24 and 30 volume percentages of carbonyl iron (CI) particles. Prepared MR fluid samples contain CI particles as a dispersive medium, silicone oil as a carrier fluid and white lithium grease as an anti-settling agent. The oscillating driving frequency and amplitude strain sweep tests are performed to investigate the rheological properties within the pre-yield region. The influences of driving frequency, strain amplitude, magnetic field and CI particles volume percentage on the rheological properties of the prepared MR fluids were assessed. The linear viscoelastic region of the prepared MR fluid sample was identified and the yield strain obtained was around 0.371%. It is observed that the volume percentage of CI particles in the MR fluid strongly influenced the rheological properties. © 2022 Materials and Energy Research Center. All rights reserved.
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    A study on magnetorheological and sedimentation properties of soft magnetic Fe58Ni42 particles
    (Elsevier B.V., 2022) Aruna, M.N.; Rahman, M.R.; Joladarashi, S.; Kumara, H.; Meena, S.S.; Sarkar, D.; Umesh, C.K.
    In this study, the samples with two volume fractions (ϕ) of Fe58Ni42 (permalloy) i.e. (ϕ1 = 25 and ϕ2 = 30 %) were used as magnetic particles, silicone oil as a carrier fluid, and aluminium disterate as an additive. As received Fe58Ni42 particles surface morphology and composition of the Fe58Ni42 were investigated using field emission scanning electron microscopy (FESEM) coupled with energy dispersive spectroscopy (EDS), respectively. The X-ray Diffraction (XRD) structural information analysis confirmed Fe58Ni42 particles have a face-centered cubic phase, corresponding with the result of the high resolution transmission electron microscopy (HRTEM) characterization technique. The magnetorheological properties were tested via rotational rheometer at four different magnetic field strengths. The results show that sample PMRF-30 has a maximum shear stress, shear viscosity, and dynamic modulus greater than the PMRF-25 sample. In addition, experimental shear stress flow curves are well fitted with Herschel-Bulkley rather than Bingham and Casson rheological models. The permalloy based magnetorheological fluid (PMRF) samples were prepared with a 25 % volume fraction and a 30 % volume fraction of permalloy particles with a sample abbreviation of PMRF-25 and PMRF-30, respectively. Furthermore, the sedimentation stability of suspensions of both the samples was observed using visual inspection. This method result shows the sedimentation ratio with respect to time of 72 h was 31 % and 29 %, respectively. © 2022 Elsevier B.V.
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    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.