Faculty Publications

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Author: search.filters.author.Kumar, H.Subject: search.filters.subject.Damping

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    Vertical dynamic analysis of a quarter car suspension system with MR damper
    (Springer Verlag service@springer.de, 2017) Hemanth, K.; Kumar, H.; Gangadharan, K.V.
    This paper presents ride comfort and road holding analysis of passive and semi-active suspension system using quarter car model. Semi-active suspension system with magnetorheological (MR) damper was modeled as non-parametric model-based magnetic flux density in the fluid flow gap. The skyhook control strategy was used to analyze semi-active control performance. The simulation of passive and semi-active suspension system was carried out under random road profile for different velocities. The result shows that semi-active suspension has significant improvement in terms of ride comfort and road holding of vehicle than passive suspension system. Experimental studies have been conducted to characterize MR damper and a good match is observed between results with simulation results obtained using non-parametric model. © 2016, The Brazilian Society of Mechanical Sciences and Engineering.
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    Optimisation of monotube magnetorheological damper under shear mode
    (Springer Verlag service@springer.de, 2017) Gurubasavaraju, T.M.; Kumar, H.; Mahalingam, M.
    Magnetorheological dampers (MR) are one of the semi active devices, which has the capability of providing variable damping force for the variable input current. Induced force is directly dependent on the amount of magnetic flux density developed in effective fluid flow gap of the MR damper. In the present work, influence of material properties on the magnetic flux is investigated by considering magnetic and nonmagnetic material for the outer cylinder of shear mode type MR damper. Magnetostatic analysis is carried out to obtain magnetic flux density for the initial configuration of the MR damper. From the analysis, it is found that usage of magnetic material cylinder which is insulated with nonmagnetic material provided higher value of magnetic flux and damping force. The geometric optimisation of MR damper is carried out to obtain the maximum flux density in the fluid flow gap. The objective function of the optimisation includes the maximum magnetic flux density and minimising fluid flow gap. Design variables considered are fluid flow gap, number of turns in the electromagnetic coil, length of the flange and DC current input. The optimisation is performed through response surface method using finite element analysis software (ANSYS). The best optimal design parameters are obtained by choosing the appropriate value of objective function. The best configuration of the design parameters, which induce the maximum magnetic flux density, is identified. The force induced in the MR damper is estimated analytically and a comparative study of the optimised and non-optimised results was carried out. © 2017, The Brazilian Society of Mechanical Sciences and Engineering.
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    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.
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    An approach for characterizing twin-tube shear-mode magnetorheological damper through coupled FE and CFD analysis
    (Springer Verlag service@springer.de, 2018) Gurubasavaraju, T.M.; Kumar, H.; Mahalingam, A.
    The most promising technology in the field of semi-active suspension systems is the use of magnetorheological property of MR fluid, whose material behavior can be controlled through external magnetic field. Devices developed based on this principle are adaptive and controllable as desired for a specific application. It is important to understand the damping characteristics of these devices before employing them, using experimental or computational approaches. In the present work, both experimental and computational methods have been adopted for characterizing a twin-tube MR damper with an intention to develop a computational approach as an alternative to experimental test in the preliminary design stage. Initially, experimental characterization of MR damper was carried out at 1.5 and 2 Hz frequencies for damper stroke length of ± 5 mm under different DC currents ranging from 0.1 to 0.4 A. Later, coupled finite-element and computational fluid dynamic analysis has been carried out to estimate the damping force under same conditions as used in the experiment. The results of computation are in good agreement with experimental ones. Furthermore, using this computational approach, the damping force at different frequencies of 1.5, 2, 3, and 4 Hz has been estimated and its time histories are also plotted. The influence of fluid flow gap on the damping force has been determined and results revealed that damping force behaves inversely with fluid flow gap. © 2018, The Brazilian Society of Mechanical Sciences and Engineering.
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    Dynamic analysis of half car model with MR damper as semi-active suspension element
    (International Institute of Acoustics and Vibrations P O Box 13 Auburn AL 36831, 2018) Hemanth, K.; Kumar, H.; Gangadharan, K.V.
    This paper presents the dynamic analysis of a half-car model with a magnetorheological (MR) damper subjected to random excitation. Experimental studies have been conducted to predict the behavior of the prototype twin-tube MR damper. The mathematical model of the prototype MR damper has been proposed by using the Bouc-Wen model. The half-car model with the MR damper has been used to predict the ride comfort and road holding performance. Comparative studies between the half-car model with the passive and semi-active suspension system with a proportional-integral-derivative (PID) control shows that the MR damper suspension system offers a good performance. © 2018 International Institute of Acoustics and Vibrations. All Rights Reserved.
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    Dynamic analysis and optimization of SiC reinforced Al6082 and Al7075 MMCs
    (Institute of Physics Publishing helen.craven@iop.org, 2019) Allien, V.J.; Kumar, H.; Desai, V.
    Composites play a vital role in engineering applications. The main aim of this study was to analyse how addition of SiC will improve the damping properties of metal matrix composites (MMCs). The strengthening of composites depends on physical, mechanical and dynamic factors. In the present study, Al6082 and Al7075 aluminum alloy reinforced with (0, 1, 2, 3, 4, 5, 7.5, 10, 15 and 20) different weight percentages of silicon carbide particles (SiCp) MMCs have been fabricated through stir casting method. The microstructure, density, hardness, tensile strength, impact strength, natural frequencies and damping ratio of the MMCs were determined. The mechanical tests and free vibration analysis results revealed that the addition of SiCp reinforcement enhanced the strength and stiffness of the aluminum alloy MMCs. Multi-attribute decision making (MADM) techniques like analytic hierarchy process (AHP) and technique for order preference by similarity to ideal solution (TOPSIS) methods were applied for determining the best fabricated MMCs. Based on MADM techniques, 15% SiC/Al7075 composite was selected as the best material and using response surface methodology (RSM) 13.66% SiC/Al7075 composite was found as the optimal composite material. © 2019 IOP Publishing Ltd.
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    Performance analysis of a semi-active suspension system using coupled CFD-FEA based non-parametric modeling of low capacity shear mode monotube MR damper
    (SAGE Publications Ltd, 2019) Gurubasavaraju, G.; Kumar, H.; Mahalingam, A.
    In this work, an approach for formulation of a non-parametric-based polynomial representative model of magnetorheological damper through coupled computational fluid dynamics and finite element analysis is presented. Using this, the performance of a quarter car suspension subjected to random road excitation is estimated. Initially, prepared MR fluid is characterized to obtain a relationship between the field-dependent shear stress and magnetic flux density. The amount of magnetic flux induced in the shear gap of magnetorheological damper is computed using finite element analysis. The computed magnetic field is used in the computational fluid dynamic analysis to calculate the maximum force induced under specified frequency, displacement and applied current using ANSYS CFX software. Experiments have been conducted to verify the credibility of the results obtained from computational analysis, and a comparative study has been made. From the comparison, it was found that a good agreement exists between experimental and computed results. Furthermore, the influence of fluid flow gap length and frequency on the induced force of the damper is investigated using the computational methods (finite element analysis and computational fluid dynamic) for various values. This proposed approach would serve in the preliminary design for estimation of magnetorheological damper dynamic performance in semi-active suspensions computationally prior to experimental analysis. © IMechE 2018.
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    Design and experimental characterization of a twin-tube MR damper for a passenger van
    (Springer Verlag service@springer.de, 2019) Desai, R.M.; Jamadar, M.E.H.; Kumar, H.; Joladarashi, S.; Raja Sekaran, S.C.
    The smart behavior of magneto-rheological (MR) fluid is used in the present work in designing, experimentally characterizing and analyzing a MR damper for automotive application using the twin-tube damper concept. A commercially available passive damper of a passenger van was tested to find the characteristic damping requirement of the vehicle. With this as reference, a twin-tube MR damper working in valve mode was designed and fabricated. The magnetic flux density induced in the fluid flow gap is maximized using Taguchi analysis and finite element method magnetics (FEMM) software. The FEMM results are validated by verifying with results obtained analytically using electromagnetic circuit theory. The MR damper filled with commercially available MR fluid was experimentally tested in damper testing machine. The results demonstrate that the force developed by the MR damper is indeed increasing with the value of the current supplied. At various frequencies of input oscillation, the energy dissipated by the MR damper in a single cycle increases significantly with current supplied. The novelty of this work is that a twin-tube MR damper working in valve mode was designed as a replacement for the passive damper used in a passenger van. The MR damper thus developed is capable of producing practical levels of damping force at actual operating frequencies and amplitudes of the passive damper in the passenger van. For further analysis, the behavior of the MR damper is modeled by using the Bouc–Wen model for hysteretic systems. A proportional–integral–derivative controller is used to track the desired damping force in time domain to demonstrate the application of the MR damper in a semi-active suspension system. © 2019, The Brazilian Society of Mechanical Sciences and Engineering.
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    Evaluation of a commercial MR damper for application in semi-active suspension
    (Springer Nature, 2019) Desai, R.M.; Jamadar, M.E.H.; Kumar, H.; Joladarashi, S.; Rajasekaran, S.C.; Amarnath, G.
    As the rheology of a magneto-rheological (MR) fluid can be controlled by an externally applied magnetic field, the damping force generated by a MR damper can be controlled by varying the current supplied to an electromagnet inside the damper. This paper presents the experimental evaluation of such a MR damper RD-8040-1 by Lord Corporation, USA, and its application in a semi-active suspension. The experiments were carried out in damping force testing machine. Sinusoidal displacement input was given to the test damper. The set of experiments were repeated for different levels of current (0–1.5 A in steps of 0.25 A) supplied to the MR damper. Plots of force versus displacement for each frequency of excitation and plots of maximum force versus frequency of excitation show that higher values of current lead to elevated values of MR damper forces. This increase in MR damper load with current supplied is studied and analyzed to develop a mathematical model of the MR damper under investigation. The nonlinear softening hysteretic behavior of the MR damper is simulated by using genetic algorithm provided in the optimization toolbox of MATLAB. Calculations on energy dissipation and equivalent damping coefficient of the MR damper show that the same damper can make the suspension system behave as an underdamped system, critically damped system or overdamped system depending on the value of current supplied to it. The application of this MR damper for heavy vehicle driver’s seat suspension is explored with the help of MATLAB simulations. © 2019, Springer Nature Switzerland AG.
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    Determination of optimal magnetorheological fluid particle loading and size for shear mode monotube damper
    (Springer Verlag service@springer.de, 2019) Acharya, S.; Saini, R.S.S.; Kumar, H.
    Magnetorheological (MR) fluids belong to a class of controllable fluids, and the composition and concentration of its components govern its magnetorheological properties. In this study, an optimum particle loading (or mass fraction) and size of iron particles in MR fluid for use in a shear mode monotube MR damper were determined based on the damping force and off-state viscosity of synthesized MR fluid samples. Initially, the morphological and magnetic properties of carbonyl iron particles were characterized. Six MR fluid samples were prepared composed of combination of three different particle loadings and two sizes of iron particles. Magnetorheological tests were conducted on these samples to determine the flow curves at off-state and on-state magnetic field conditions. Herschel–Bulkley model was used for mathematical representation of flow curves at different magnetic fields and to determine their dynamic yield stress. Further, a shear mode monotube MR damper with accumulator was designed by using optimization technique for desired dynamic range and damping force. Magnetostatic analysis was performed to determine the magnetic field strength generated in the shear gap at different currents. The damping force was calculated for synthesized MR fluids based on their dynamic yield stress corresponding to the magnetic field strength in the shear gap. Analysis of variance was performed to analyse the significance of independent factors on the damping force and off-state viscosity of MRF. The optimal particle loading and size which yielded maximum damping force with minimum off-state viscosity were determined using a multi-objective genetic algorithm. © 2019, The Brazilian Society of Mechanical Sciences and Engineering.