Journal Articles
Permanent URI for this collectionhttps://idr.nitk.ac.in/handle/123456789/19884
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Item Simultaneous estimation of unknown parameters using a-priori knowledge for the estimation of interfacial heat transfer coefficient during solidification of Sn–5wt%Pb alloy—an ANN-driven Bayesian approach(Springer, 2019) Vishweshwara, P.S.; Gnanasekaran, N.; Arun, M.The present methodology focuses on model reduction in which the prevalent one-dimensional transient heat conduction equation for a horizontal solidification of Sn–5wt%Pb alloy is replaced with Artificial Neural Network (ANN) in order to estimate the unknown constants present in the interfacial heat transfer coefficient correlation. As a novel approach, ANN-driven forward model is synergistically combined with Bayesian framework and Genetic algorithm to simultaneously estimate the unknown parameters and modelling error. Gaussian noise is then added to the temperature distribution obtained using the forward approach to represent real-time experiments. The hallmark of the present work is to reduce the computational time of both the forward and the inverse methods and to simultaneously estimate the unknown parameters using a-priori engineering knowledge. The results of the present methodology prove that the simultaneous estimation of unknown parameters can be effectively obtained only with the use of Bayesian framework. © 2019, Indian Academy of Sciences.Item Inverse approach using bio-inspired algorithm within Bayesian framework for the estimation of heat transfer coefficients during solidification of casting(American Society of Mechanical Engineers (ASME), 2020) Vishweshwara, P.S.; Gnanasekaran, N.; Arun, M.In any parameter estimation problem, it is desirable to obtain more information in one single experiment. However, it is difficult to achieve multiple objectives in one single experiment. The work presented in this paper is the simultaneous estimation of heat transfer coefficient parameters, latent heat, and modeling error during the solidification of Al-4.5 wt %Cu alloy with the aid of Bayesian framework as an objective function that harmoniously matches the mathematical model and measurements. A 1D transient solidification problem is considered to be the mathematical model/forward model and numerically solved to obtain temperature distribution for the known boundary and initial conditions. Genetic algorithm (GA) and particle swarm optimization (PSO) are used as an inverse approach and the estimation of unknown parameters is accomplished for both pure and noisy temperature data. The use of Bayesian framework for the estimation of unknown parameters not only provides the information about the uncertainties associated with the estimates but also there is an inherent regularization term in which the inverse problem boils down to well-posed problem thereby plethora of information is extracted with less number of measurements. Finally, the results of this work open up new prospects for the solidification problem so as to obtain a feasible solution with the present approach. © © 2020 by ASMEItem Vibration analysis of fully and partially filled sandwiched cantilever beam with magnetorheological fluID(Taylor's University, 2020) Srinivasa, N.; Gurubasavaraju, T.M.; Kumar, H.; Arun, M.This paper presents the experimental and computational study on damping effect of the fully and partially filled sandwich cantilever beams. The sandwich beams referred as adaptive beams have a core layer filled with magnetorheological fluid (MRF) between two aluminium face plates. Forced vibration tests were conducted under different magnetic fields with the application of external force in the form of sinusoidal sweep excitation using an electrodynamic shaker. Effect on damping and natural frequency due to change in MR fluid core thickness of 2 mm, 4 mm and 6 mm for the fully filled beam and fluid core length of 75 mm, 150 mm and 250 mm for partially filled beam were investigated. Modal and harmonic analysis of the MR sandwich beams were carried out using FE analysis. The results indicated that in the case of the fully filled beam, a reduction in the natural frequency with the increase in MR fluid core thickness and a better damping at 2 mm fluid core thickness were observed. Also, in the case of the partially filled beam a reduction in natural frequency and improvement in damping is found with the increase in core length and magnetic field. The results of these analyses can be useful in designing the sandwich beams for structural application. © School of Engineering, Taylor's UniversityItem Influence of temperature on magnetorheological fluid properties and damping performance(IOP Publishing Ltd, 2022) Kumar Kariganaur, A.; Kumar, H.; Arun, M.The magnetorheological (MR) system's performance depends on the MR fluid's temperature in operation. This study aims to evaluate the temperature effect of MR fluid on performance while the damper is working. Before synthesizing MR fluid, scanning electron microscopy, x-ray diffraction, and particle size analysis verifies for the synthesis of MR fluid in-house. Characterization of the MR fluid at different temperatures and magnetic fields was carried out. The Herschel-Bulkley model is used to analyse the nonlinearity in the fluid by incorporating the temperature effect. The range of critical parameters used to fabricate the MR damper is selected using the Technique for Order of Preference by Similarity to Ideal Solution performance score. The temperature of the MR fluid is measured using an embedded thermocouple while the damper is operating at different loading parameters. The results reveal that the fluid temperature rises significantly from atmospheric to 125.39 °C with decrease in damping force by 66.32% at higher loading parameters. The theoretical model predicts the increase in temperature similar to that of the experimental values with an average error of 10.24% in the on-state condition. Particle characterization after dynamic testing reveals particle morphology has not changed but the saturation magnetization of the particles reduced by 57% at higher temperatures (127 °C). It is observed through thermogravimetric analysis that, the life of the fluid is reduced by 0.25%, which is negligible after dynamic testing of the fluid for approximately 85000 cycles. Finally, to imitate the temperature effect on the particle, particles were heat-Treated at 200 °C, 400 °C, and 600 °C, and through scanning electron microscope image it is confirmed that deterioration of the particle starts after 200°C, if the fluid is operated for a prolonged amount of time. © 2022 IOP Publishing Ltd.Item Effect of temperature on sedimentation stability and flow characteristics of magnetorheological fluids with damper as the performance analyser(Elsevier B.V., 2022) Kumar Kariganaur, A.; Kumar, H.; Arun, M.dimentation stability and high yield stress of a magnetorheological fluid (MRFs) are essential parameters for better damping performance for any practical application. Preliminary investigations have been carried out on carbonyl iron particles to determine the morphology, particle size, crystal structure, and saturation magnetization for their feasibility of synthesizing magnetorheological fluids in-house. This study synthesizes various MRFs from various commonly used carrier oils and additives. The MRF samples were prepared for 25% volume fractions of carbonyl iron (CI) powder in either silicone oil (350cSt) or hydraulic oil (50cSt) and by using lithium and calcium-based additives or a combination of both the additives. The sedimentation stability and yield behaviour at different temperatures show a remarkable drop in sedimentation rate and yield stress for all the MR fluid samples. The characterization of the prepared MR fluids reveals that MRF-1, MRF-3, MRF-5 are more stable and have high yield stress values. MRF-1 is selected to further characterize its dynamic performance in magnetorheological damper fabricated based on geometric dimensions obtained from the response surface optimization technique. The results indicate a 164.45% and 135.48% increase in damping force at higher amplitude and higher frequencies at 0A and 1A currents. Further, similar tests have been carried out by synthesizing MRF-7 with silicone oil (50cSt) + lithium base grease as the additive. The sample's stability and yield stress with temperature are carried out, and performance analysis shows a remarkable change in damping force than MRF-1. The dynamic range obtained is practically viable in MRF-7 than MRF-1, with less variability. Finally, temperature characteristics captured from the thermocouple of the MR damper reveal that an average of 43.78% reduction in damping force when the temperature is increased by 19.5 °C with increased dynamic range. © 2022 Elsevier B.V.Item Impact of increased particle concentration on magnetorheological fluid properties and their damping performance(Korean Society of Rheology, Australian Society of Rheology, 2022) Kariganaur, A.K.; Kumar, H.; Arun, M.Magnetorheological (MR) fluid properties are essential in analyzing the performance of any MR fluid system. The fluid properties are dependent on shape, size, and magnetic saturation of the magnetic particles. Preliminary characteristics with SEM, particle size analysis (PSA), and vibration sample magnetometer (VSM) on carbonyl iron particles were performed to verify the particle’s feasibility to synthesize the MR fluid in a laboratory. Synthesis and characterization of MR fluids with particle concentrations (PC) of 10% (PC10), 15% (PC15), 20% (PC20), 30% (PC30), and 35% (PC35) by volume are carried out. To show the inherent nonlinearity of the MR fluid, Herschel–Bulkley model is used. The relationship between sedimentation velocity, yield stress, and thermal conductivity is established as a function of particle concentration with experimental uncertainty of 6.15, 5, and 8.96%, respectively. Functional testing of PC15 and PC30 was carried out on an MR damper fabricated on dimensions obtained from the literature for the required size. The results indicate that damping force is 42% more in PC30 than PC15 at higher loading parameters. Finally, the saturation magnetization of the MR fluid depends not only on applied current but also on loading parameters when operating in the system. © 2022, Korean Society of Rheology.Item Effect of reduced geometric dimensions on torque generation in two plate rotor magnetorheological brake with in-house magnetorheological fluid(Institute of Physics, 2023) Kariganaur, A.K.; Kadam, S.; Kumar, H.; Arun, M.The present study is aimed to evaluate the torque generation capacity of a two plate rotor magnetorheological (MR) brake using in-house prepared MR fluid. The prepared MR fluids were studied for sedimentation rate at different temperatures and flow characterization at different currents and at specific temperatures. The yield stress of the fluid is explored through Herschel-Bulkley model. The results depict significant increase in sedimentation rate and decrease in yield stress with increase in temperature of the MR fluid. MR brake (model-1) is fabricated after finite element method magnetics exhibit magnetic field of approximately 0.145 T in the shear gap than other two models (model-2 and model-3) considered in this study. Characterization of the MR brake illustrates that there is an increase in torque with increasing current. Further tests have been carried out to identify the effect of sedimentation on torque generation at 52 °C after 15 h of sedimentation. The results indicate 16% reduction in the initial torque because of settling of particles. MR fluid and particles characterization illustrates that 322 °C and 400 °C are critical points in controlling the MR fluid input parameters. © 2023 IOP Publishing Ltd.Item Study on operational temperature of magneto-rheological fluid and design dimensions of magneto-rheological damper for optimization(Institute of Physics, 2024) Kumar Kariganaur, A.; Kumar, H.; Arun, M.This study aims to restrict the upper limit for flow gap and effective length in magnetorheological (MR) damper for optimal performance. Initially, the sedimentation study of in-house MR fluid (25%) shows that an 8% reduction in the sedimentation ratio with the addition of additive and nonlinear Herschel-Bulkley (HB) model fit reflects a 32.5% decrease in average yield stress with increasing currents when the parallel plate gap is increased from 1 mm to 2 mm. Owing to this decrease in yield stress, further study is extended to fabricate two MR dampers with limit values (LV) of flow gap and effective length with a common magnetic outer cylinder. Testing results of MR dampers revealed a 72% reduction in damping force at 0.8 A current when the LV’s is increased from LV-1 to LV-2. Selecting LV-1 over LV-2 as the upper limit for any design optimization will give the MR damper optimal performance. At higher input parameters, amplitude has a 135% greater impact on damping force than frequency and current. It is also demonstrated that saturation magnetization depends on the applied magnetic field and input loading parameters. Finally, gravimetric analysis shows that the effectiveness of the MR fluid and magnetic particle starts to decline after 322 °C and 400 °C. © 2024 IOP Publishing Ltd.Item Design and Development of Internal Wound Magnetorheological Elastomer Mount for Structural Vibration Isolation(Springer, 2025) Bhat, S.H.; Saroj, A.A.; Kumar, H.; Arun, M.; Vaidyanathan, R.V.Vibration isolation of structures is crucial for enhancing reliability when subjected to mechanical vibrations and shocks. This research investigates the application of Magneto-Rheological Elastomer (MRE) mounts to mitigate vibrations in a 15 kg structure. A unique MRE mount with internal windings was designed and developed using magneto-static analysis with maximizing magnetic flux density across MRE through the Design of Experiments (DoE). MRE samples were prepared considering 20, 40 and 60% (wt.) carbonyl iron particle (CIP) content within a silicon elastomer matrix and analyzed under a rheometer. Further, these MRE samples were considered for forced vibration studies with structures placed on MRE mounts across different frequencies. Repeated experiments with all in-house MRE samples demonstrated that the MRE mount significantly mitigated vibrations at different currents and compositions. The transmissibility plot revealed a maximum amplitude reduction of 3.73 times for the 60% MRE sample. These results underscore the importance of optimizing MRE mount and CIP content for effective vibration isolation, which is vital for prolonging the operational lifespan of critical structures. © The Institution of Engineers (India) 2025.Item Design and Development of Multi-Mode Magneto-Rheological Fluid Mount for Structural Vibration Isolation(Springer, 2025) Bhat, S.H.; Kumar, H.; Arun, M.; Vaidyanathan, R.V.Purpose: The study investigates the application of Magneto-Rheological Fluid (MRF) mounts as semi-active vibration control solutions for critical structures, with the primary objective of developing a unique multi-mode MRF mount and in-house MRF optimization for effective vibration isolation. Methods: In-house MRF is synthesized with varying carbonyl iron particle concentrations and characterized to understand its rheological behavior under different current levels. A unique multi-mode MRF mount is developed to operate simultaneously in squeeze, flow, and shear modes, utilizing a translatory-to-rotary motion conversion mechanism. Magneto-static analysis of various design configurations is conducted in ANSYS to achieve a higher magnetic flux density across the MRF gap—a critical parameter for MRF mount performance. The configuration yielding the highest magnetic flux density is selected for fabrication and is tested with in-house MRF samples under varying currents. Based on the characterization results, fluid optimization is performed using Response Surface Methodology (RSM) to maximize damping ratio and yield stress, which directly impact vibration isolation performance. Modal analysis of a specific structure is conducted to determine its characteristics, followed by forced vibration analysis with MRF mounts powered individually at varying currents. Results: Transmissibility plots demonstrate that the developed multi-mode MRF mount effectively reduces vibrations, achieving up to 48% isolation under applied currents. Conclusion: The multi-mode MRF mount shows strong potential as a semi-active vibration isolation solution. Its significant vibration isolation capability under current influence highlights its suitability for various critical structures and supports its use in vibration-sensitive applications. © Springer Nature Singapore Pte Ltd. 2025.