Faculty Publications
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Item Investigation of steady state rheological properties and sedimentation of coated and pure carbonyl iron particles based magneto-rheological fluids(Elsevier Ltd, 2020) Swaroop, K.V.; Aruna, M.N.; Kumar, H.; Rahman, M.R.MR fluids face a major problem of sedimentation rate due to the high- density difference between the magnetic particles and the carrier medium that affects the performance of the magnetorheological devices. In this work, two MRF samples are prepared, where MRF-1 and MRF-2 are pure and coated carbonyl iron particles (CIPs) based MR fluids. The surface modification of the CIPs is performed using the solvent dispersion method to improve the sedimentation rate. The spherical shape and particle size analysis of the pure CIPs and coated CIPs' morphology is investigated using the Scanning Electron Microscope (SEM). The Thermal Gravimetric Analysis (TGA) shows that the coated CIPs have high thermal stability and confirm that 6% by wt. coating is present in the coated sample. The chemical bonding of the coated CIPs is detected using the Fourier Transform Infrared Spectroscopy (FT-IR). The saturation magnetization (Ms) of pure and coated CIPs is 245 emu/g and 120 emu/g, respectively, at 15 kOe, which is obtained by using a superconducting quantum interface device (SQUID). The rheology flow curve properties show that MRF-1 and MRF-2 exhibit yield stress of about 10 kpa and 9 kpa, respectively, for varying magnetic fields ranging from 0 to 343 kA/m. The Herschel-Bulkley model is fitted with the experimental data and the shear thinning behaviour is observed for both MR fluids. The sedimentation study shows that MRF-2 has better settling rate than MRF-1, which is observed by using the visual observation method up to 600 h. © 2020 Elsevier Ltd. All rights reserved.Item Semi-active vibration control of SiC-reinforced Al6082 metal matrix composite sandwich beam with magnetorheological fluid core(SAGE Publications Ltd info@sagepub.co.uk, 2020) Allien, J.V.; Kumar, H.; Desai, V.Dynamic characterization of silicon carbide particles reinforced Al6082 alloy metal matrix composite sandwich beam with magnetorheological fluid core is experimentally investigated. The study is focused on determining the effect of magnetorheological fluid core on the dynamic behavior of the sandwich structure. The magnetorheological fluid core is enclosed between the top and bottom metal matrix composite beams. The metal matrix composite beams are cast with silicon carbide particles in Al6082 alloy varying from 0 to 20 wt%. The magnetorheological fluid is prepared in-house and contains 30 vol.% carbonyl iron powder and 70 vol.% silicone oil. The free vibration test is conducted to determine the natural frequencies and damping ratio. It is found that the natural frequencies and damping ratio of the sandwich beams increased with an increase in the applied magnetic flux density. The experimental forced dynamic response of sandwich beams is carried out using sine sweep excitation. Vibration amplitude suppression capabilities of the sandwich beams subjected to varying magnetic flux densities are determined. The experimental forced vibration results reveal that metal matrix composite–magnetorheological fluid core sandwich beams have excellent vibration amplitude suppression capabilities. © IMechE 2019.Item Dynamic behavior of sandwich beams with different compositions of magnetorheological fluid core(Taylor and Francis Ltd., 2021) Acharya, S.; Allien, V.J.; Puneet, P.; Kumar, H.Magnetorheological fluid (MRF) sandwich beams belong to a class of adaptive beams that consists of MRF sandwiched between two or more face layers and have a great prospective for use in semi-active control of beam vibrations due to their superior vibration suppression capabilities. The composition of MRF has a strong influence on the MRF properties and hence affects the vibration characteristics of the beam. In this work, six MRF samples (MRFs) composed of combination of two particle sizes and three weight fractions of carbonyl iron powder (CIP) were prepared and their viscoelastic properties were measured. The MRFs were used to fabricate different MRF core sandwich beams. Additionally, a sandwich beam with commercially available MRF 132DG fluid as core was fabricated. The modal parameters of the cantilever MRF sandwich beams were determined at different magnetic fields. Further, sinusoidal sweep excitation tests were performed on these beams at different magnetic fields to investigate their vibration suppression behavior. MRF having larger particle size and higher weight fraction of CIP resulted in higher damping ratio and vibration suppression. Finally, optimal particle size and weight fraction of CIP were determined based on the maximization of damping ratio and minimization of weight of MRF. © 2021 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.