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Author: search.filters.author.Kumar H.Start date: 2020

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    Study the dynamic behaviour of seven DOF of full car model with semi-active suspension system
    (2021) Krishna H.; Vasanth S.; Sonnappa D.; Kumar H.; Gangadharan K.
    This paper presents an investigation on the ride comfort and road-holding performance of a vehicle equipped with the semi-active suspension system. The full car semi-active suspension model with 7 degrees of freedom (7 DOF) system is adopted for the study and a fuzzy-logic control strategy is considered for minimising the effect of road disturbance on vehicle performance. The responses of a vehicle have been analysed under the Indian average random road profile (ISO8608) against the conventional passive suspension system. The performance of the semi-active suspension system is evaluated by heave, roll and pitch acceleration of the vehicle body around its centre of gravity. The performance of a vehicle with the semi-active suspension system has been compared with the response conventional passive suspension system. The result specifies that, the semi-active suspension system with a fuzzy-logic controller reduces around 43% of vibration amplitude at the resonance frequency of vehicle than the passive suspension system. Copyright © 2021 Inderscience Enterprises Ltd.
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    Selection of optimal composition of MR fluid for a brake designed using MOGA optimization coupled with magnetic FEA analysis
    (2020) Acharya S.; Saini T.R.S.; Sundaram V.; Kumar H.
    The design of Magnetorheological (MR) brake and the composition of MR fluid (MRF) used in it have a significant effect on its performance and hence an effort has been made in this study to determine the optimal dimensions of MR brake and composition of MRF suitable for the brake application. Initially, optimum parameters of MR brake were computed considering the properties of commercially available MRF 132DG fluid using multi-objective genetic algorithm (MOGA) optimization. This was performed in MATLAB software coupled with magnetostatic analyses in ANSYS APDL software. The braking torque of designed MR brake utilizing MRF 132DG fluid was experimentally determined and validated with analytical ones. Further, selection of optimal composition of MRF was done considering In-house MRF samples composed of different combinations of particle mass fractions, mean particle diameters and base oil viscosities. A design of experiments (DOE) technique was employed and braking torque corresponding to the synthesized MRF samples at different speeds and current supplied were measured along with the variation of shaft speed during braking process. Grounded on the experimental results, using MOGA optimization technique, MRF composed of smaller sized iron particles (2.91 microns) with mass fraction of 80.95% and lower viscosity base oil (50 cSt) was selected as optimal composition of MRF for use in MR brake. Maximization of field induced braking torque and minimization of off-state torque were chosen as the objective functions for both the optimal design of MR brake and selection of optimal composition of MRF. Finally, the sedimentation stability of MRFs were investigated. © The Author(s) 2020.
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    Performance Evaluation of a Single Sensor Control Scheme Using a Twin-Tube MR Damper Based Semi-active Suspension
    (2021) Desai R.M.; Jamadar M.-E.-H.; Kumar H.; Joladarashi S.
    Background: Magneto-rheological (MR) dampers have a promising future for application in automotive semi-active suspensions. The damping force produced by MR dampers can be modulated by controlling the electric current supplied to it. Purpose: The present work explores a twin-tube MR damper working in valve mode for application in a semi-active SUV suspension system. Further, the performance of a single sensor control scheme is evaluated. Methods: The MR damper is characterized in a damper testing machine to demonstrate the MR behaviour and also to show that it develops similar magnitude of force as a passive damper used in SUV suspension. To prove the superiority of semi-active suspension, a single degree of freedom quarter car test rig is built and ground excitation is given in the form of displacement input from a hydraulic actuator. Constant current control, Skyhook control and Rakheja-Sankar (RS) control method are employed as three different control strategies and compared with passive suspension to study the advantages. Peak acceleration response of the sprung mass is studied for better passenger ride comfort and peak ground force is studied for preventing damage to road surface as well as to vehicle suspension elements. Results: RS control provides much lower sprung mass vertical acceleration than Skyhook control and constant current control. RS control method led to 36% reduction of peak ground force when compared to Skyhook control. Conclusion: For a semi-active suspension using twin-tube MR damper, RS control method provides better ride comfort to passengers due to lower peak vertical acceleration when compared to constant current control or Skyhook control method. Moreover, for preventing damage to road surface as well as to vehicle suspension elements, RS control method, requiring a single sensor, is a much better choice. © 2021, Krishtel eMaging Solutions Private Limited.
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    Particulate matter (PM10) enhances RNA virus infection through modulation of innate immune responses
    (2020) Mishra R.; Krishnamoorthy P.; Gangamma, S.; Raut A.A.; Kumar H.
    Particulate matter (PM10) enhances severity of influenza virus infection through skewing innate immunity via modulation of metabolic pathways-related genes. © 2020 Elsevier LtdSensing of pathogens by specialized receptors is the hallmark of the innate immunity. Innate immune response also mounts a defense response against various allergens and pollutants including particulate matter present in the atmosphere. Air pollution has been included as the top threat to global health declared by WHO which aims to cover more than three billion people against health emergencies from 2019 to 2023. Particulate matter (PM), one of the major components of air pollution, is a significant risk factor for many human diseases and its adverse effects include morbidity and premature deaths throughout the world. Several clinical and epidemiological studies have identified a key link between the PM existence and the prevalence of respiratory and inflammatory disorders. However, the underlying molecular mechanism is not well understood. Here, we investigated the influence of air pollutant, PM10 (particles with aerodynamic diameter less than 10 μm) during RNA virus infections using Highly Pathogenic Avian Influenza (HPAI) – H5N1 virus. We thus characterized the transcriptomic profile of lung epithelial cell line, A549 treated with PM10 prior to H5N1infection, which is known to cause severe lung damage and respiratory disease. We found that PM10 enhances vulnerability (by cellular damage) and regulates virus infectivity to enhance overall pathogenic burden in the lung cells. Additionally, the transcriptomic profile highlights the connection of host factors related to various metabolic pathways and immune responses which were dysregulated during virus infection. Collectively, our findings suggest a strong link between the prevalence of respiratory illness and its association with the air quality. © 2020 Elsevier Ltd
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    Optimal design of inverted rotary MR brake with waveform boundary using a novel combined magnetostatic approach
    (2020) Saini R.S.T.; Kumar H.; Chandramohan S.
    In the present work, an inverted rotary drum magneto rheological (MR) brake with waveform arc boundary suitable for prosthetic knee application is optimally designed. Often, the magnetostatic analysis is performed assuming linear magnetic systems and solving a lumped parametric equivalent magnetic model (EMM). Although, this reduces the computational time but compromises the accuracy of the solution. On the other hand, finite element magnetostatic (FEMS) analysis combined with a search-based optimization technique requires more time and effort. In this work, an approach combining the EMM and FEMS methods is proposed to optimally design the MR brake. This method requires the optimization algorithm to maintain an external repository so that individuals which are non-dominated at each generation get stored in the repository and only those individuals are allowed to use FEMS method. This approach reduces the number of function calls made to FEMS method and thus reduces the computational time substantially. A recently proposed multi-objective particle swarm optimization (MOPSO) which evaluates the global best using minimum distance of point of line (MDPL) method is implemented with the proposed combined magnetostatic method. While FEMS method alone resulted in an average computational time of 7.25 h, the proposed method evaluated a similar Pareto front solution in 38 min. Finally, the optimal design is compared to other prosthetic knee MR brakes from the literature. © 2020 IOP Publishing Ltd.
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    Influence of different fumed silica as thixotropic additive on carbonyl particles magnetorheological fluids for sedimentation effects
    (2021) Aruna M.N.; Rahman M.R.; Joladarashi S.; Kumar H.; Devadas Bhat P.
    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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    Free vibration analysis and selection of composite for high strength and stiffness using multi-attribute decision making
    (2021) Allien V.; Kumar H.; Desai V.
    This paper describes the optimal selection of chopped strand mat glass-fiber-reinforced unsaturated polyester resin (CGRP) polymer matrix composite (PMC) by considering the strength and stiffness of various composite samples. The two-, four-, six-, eight- and ten-layered CGRP-PMC samples were prepared by using a hand-layup method. Then, the natural frequency and damping ratio of the CGRP-PMC samples were determined through experimental free vibration analysis using DEWESoft software. The density, tensile strength, flexural strength, impact strength, absorbed energy, inter-laminar shear strength, and fracture toughness results of the CGRP-PMC samples were considered as attributes for the selection of the optimal composite using multi-attribute decision making (MADM) techniques. The six-layered CGRP-PMC material was selected as the optimal PMC based on the results of MADM techniques. © 2021 Walter de Gruyter GmbH, Berlin/Boston, Germany 2021.
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    Fault diagnosis of internal combustion engine gearbox using vibration signals based on signal processing techniques
    (2020) KN R.; Kumar H.; GN K.; KV G.
    Purpose: The purpose of this paper is to study the fault diagnosis of internal combustion (IC) engine gearbox using vibration signals with signal processing and machine learning (ML) techniques. Design/methodology/approach: Vibration signals from the gearbox are acquired for healthy and induced faulty conditions of the gear. In this study, 50% tooth fault and 100% tooth fault are chosen as gear faults in the driver gear. The acquired signals are processed and analyzed using signal processing and ML techniques. Findings: The obtained results show that variation in the amplitude of the crankshaft rotational frequency (CRF) and gear mesh frequency (GMF) for different conditions of the gearbox with various load conditions. ML techniques were also employed in developing the fault diagnosis system using statistical features. J48 decision tree provides better classification accuracy about 85.1852% in identifying gearbox conditions. Practical implications: The proposed approach can be used effectively for fault diagnosis of IC engine gearbox. Spectrum and continuous wavelet transform (CWT) provide better information about gear fault conditions using time–frequency characteristics. Originality/value: In this paper, experiments are conducted on real-time running condition of IC engine gearbox while considering combustion. Eddy current dynamometer is attached to output shaft of the engine for applying load. Spectrum, cepstrum, short-time Fourier transform (STFT) and wavelet analysis are performed. Spectrum, cepstrum and CWT provide better information about gear fault conditions using time–frequency characteristics. ML techniques were used in analyzing classification accuracy of the experimental data to detect the gearbox conditions using various classifiers. Hence, these techniques can be used for detection of faults in the IC engine gearbox and other reciprocating/rotating machineries. © 2020, Emerald Publishing Limited.
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    Dynamic behavior of sandwich beams with different compositions of magnetorheological fluid core
    (2021) Acharya S.; Allien V.J.; N P 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.
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    Design of bypass rotary vane magnetorheological damper for prosthetic knee application
    (2020) Saini R.S.T.; Chandramohan S.; Sujatha S.; Kumar H.
    Semi-active systems using magnetorheological fluids have been realized in many novel devices such as linear dampers, rotary dampers, brakes, and so on. Rotary vane-type magnetorheological damper is one such device that uses magnetorheological fluid as a hydraulic medium and a controllable magnetorheological valve to generate variable resistance. This device, due to its limited angle motion, lends itself to a natural application for prosthetic knee joint. In this article, a bypass rotary vane-type magnetorheological damper suitable for prosthetic knee device is designed. In the proposed design, the rotary vane chamber and the bypass magnetorheological valve are connected using hydraulic cables and ports. The design of rotary cylinder is implemented based on the largest possible dimensions within the envelope of a healthy human knee, while the magnetorheological valve is designed optimally using a multi-objective genetic algorithm optimization. Off-state braking torque, induced on-state braking torque and mass of the valve are selected as three objectives. The torque and angular velocity requirements of the normal human knee are used as design limits. The optimal solution is chosen from the obtained Pareto fronts by prioritizing the objective of weight reduction of magnetorheological valve. The optimal solution is capable of producing a damping torque of 73 Nm at a design speed of 8.4 rpm and current supply of 1.9 A. Potential benefits offered by this design when compared with multi-plate magnetorheological brake are flow mode operation, large clearance gap, and fewer design components, thus reducing the manufacturing complexity. © The Author(s) 2020.