Faculty Publications
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Item 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.Item Investigation of magnetorheological brake with rotor of combined magnetic and non-magnetic materials(Springer Nature, 2019) Acharya, S.; Kumar, H.Magnetorheological (MR) brakes are a type of electromagnetic brakes that make use of controllable viscoelastic properties of magnetorheological fluid for braking. The torque capacity of the MR brake depends on the magnitude of magnetic flux density generated in the MR fluid. In this study, the effect of combination of magnetic and non-magnetic materials for rotor disk of MR brake with the objective to maximizing the flux density in the MR fluid gap at the rotor periphery was investigated. Initially, the MR brake rotor disk radius and MR fluid gap thickness were determined by using Genetic Algorithm optimization technique for desired torque ratio and torque capacity. Magnetostatic analyses were performed at different current magnitudes to determine the magnetic field and flux density in the MR brake. Further, to enhance the magnetic field intensity in the MR fluid at the rotor periphery, the rotor was modeled with three different configurations of MR brake with combinations of magnetic and non-magnetic steel and magnetostatic analyses of the MR brake were performed. It was found that the leakage of flux away from rotor periphery was reduced and there is significant increase and concentration of the magnetic field and flux density in the MR fluid gap through the use of rotor disk with combined magnetic and non-magnetic materials which would subsequently increase the torque capacity of the MR brake. © 2019, Springer Nature Switzerland AG.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.Item 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.Item Modelling and predicting the dynamic response of an axially graded viscoelastic core sandwich beam(KeAi Communications Co., 2023) Nagiredla, S.; Joladarashi, S.; Kumar, H.The present study explored the influence of axial gradation of viscoelastic materials on the dynamic response of the sandwich beam for structural applications. The finite element (FE) formulations are used to model and investigate dynamic response of the sandwich beam. The classical beam theory is used to develop the FE formulations and Lagrange's approach is considered to obtain the equations of motion (EOM). FE code is developed and validated with the existing literature and also conducted the convergence study for the developed FE method. Further, the influence of different viscoelastic materials and boundary conditions on the dynamic response of the sandwich beam is investigated. Four different axial gradation configurations of viscoelastic materials are considered for the present work to explore the influence on natural frequency, loss factor and frequency response of the sandwich beam. The modeled axial gradation of viscoelastic material has displayed a considerable impact on the peak vibrational amplitude response of the sandwich beam for all the boundary conditions and these configurations improved the damping capabilities at different configurations for the structural applications. © 2023 China Ordnance Society