Faculty Publications
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Item Statistical modeling of a magneto-rheological fluid damper using the design of experiments approach(2007) Shivaram, A.C.; Gangadharan, K.V.In this work, a through-rod-type magneto-rheological (MR) test damper has been designed and fabricated for experimental study. Various factors, such as the magnetic field strength, volume fraction of particles in the MR fluid, shearing gap between piston and cylinder, vibration frequency and amplitude, have been considered as input factors, and the root-mean-square (RMS) damping force as the output factor (response variable). These input factors are varied in two levels (low and high) during the initial phase of experimentation using 25 factorial design; the motivation is to identify the most influential factors. In the second phase of experimentation, the response surface method has been used to identify the modeling equation and to plot the response surfaces. Further, force versus displacement diagrams have been plotted at these factor levels; these give an insight into the damping behaviour of the MR damper. © IOP Publishing Ltd.Item A novel approach to investigate effect of magnetic field on dynamic properties of natural rubber based isotropic thick magnetorheological elastomers in shear mode(Central South University of Technology f-ysxb@mail.csut.edu.cn, 2015) Hegde, S.; Kiran, K.; Gangadharan, K.V.The preparation of natural rubber based isotropic thick magnetorheological elastomers (MRE) was focused on by varying the percentage volume concentration of carbonyl iron powder and developing a test set up to test the dynamic properties. Effect of magnetic field on the damping ratio was studied on the amplification region of the transmissibility curve. The viscoelastic dynamic damping nature of the elastomer was also studied by analyzing the force-displacement hysteresis graphs. The results show that MR effect increases with the increase in magnetic field as well as carbonyl iron powder particle concentration. It is observed that softer matrix material produces more MR effect. A maximum of 125% improvement in the loss factor is observed for the MRE with 25% carbonyl iron volume concentration. FEMM simulation shows that as carbonyl iron particle distribution becomes denser, MR effect is improved. FEMM analysis also reveals that if the distance between the adjacent iron particles are reduced from 20 ?m to 10 ?m, a 40% increase in stored energy is observed. © 2014, Central South University Press and Springer-Verlag Berlin Heidelberg.Item Sound radiation and transmission loss characteristics of a honeycomb sandwich panel with composite facings: Effect of inherent material damping(Academic Press, 2016) Arunkumar, M.P.; Jagadeesh, M.; Jeyaraj, J.; Gangadharan, K.V.; Mailan Chinnapandi, M.C.L.This paper presents the results of numerical studies carried out on vibro-acoustic and sound transmission loss behaviour of aluminium honeycomb core sandwich panel with fibre reinforced plastic (FRP) facings. Layered structural shell element with equivalent orthotropic elastic properties of core and orthotropic properties of FRP facing layer is used to predict the free and forced vibration characteristics. Followed by this, acoustic response and transmission loss characteristics are obtained using Rayleigh integral. Vibration and acoustic characteristics of FRP sandwich panels are compared with aluminium sandwich panels. The result reveals that FRP panel has better vibro-acoustic and transmission loss characteristics due to high stiffness and inherent material damping associated with them. Resonant amplitudes of the response are fully controlled by modal damping factors calculated based on modal strain energy. It is also demonstrated that FRP panel can be used to replace the aluminium panel without losing acoustic comfort with nearly 40 percent weight reduction. © 2016 Elsevier LtdItem 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.Item 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.Item Parametric studies on bending stiffness and damping ratio of Sandwich structures(Elsevier B.V., 2018) Rajpal, R.; Lijesh, L.; Gangadharan, K.V.Sandwich structures are extensively used in aviation industries to reduce the overall weight of the system. Although the mechanical behavior of these structures has been widely studied, the performance of core shape in vibration response has been minimally explored. This study focuses on understanding the various influences of sandwich structures considering the following parameters: (i) nature of core shape, (ii) number of infill shapes, and (iii) orientation of cores, which affect the dynamic behavior of sandwich structures. Nine sandwich structures comprising three different core shapes, hexagon, triangle, and square shapes, in three different orientations, namely 0° 45° and 90° were considered for the present study. These structures in the beginning were put by modal analysis using finite element method (FEM). All the nine structures were printed using the fused deposition method to validate the FEM findings, while the DEWE soft data acquisition system was used to estimate the modal parameters (i) natural frequency and (ii) damping ratio. Natural frequency and damping ratio were estimated using FRF and Nyquist circle plot, respectively. This study demonstrates that although the square core orientated at 0° exhibited superior stiffness in bending loads, the hexagonal core orientated at 0° displayed an admirable combination of both stiffness and damping properties. © 2018 Elsevier B.V.Item A novel method for dynamic characterization of angular displacement-dependent viscoelastic properties of magnetorheological elastomer under torsional loading conditions(Institute of Physics Publishing helen.craven@iop.org, 2019) Shenoy, S.K.; Gangadharan, K.V.The dynamic properties of magnetorheological elastomers are predominantly affected by variation in the input displacements. The displacement-dependent characteristics have been extensively studied under lateral shear, but the property variations under torsional shear have not been explored. The present study focuses on developing a novel method to study the influence of angular displacement on the dynamic properties of magnetorheological elastomers under torsional loading conditions. The experimental setup is developed according to the ISO 10846-2 standard to evaluate the variations in the dynamic torsional stiffness and loss factor. Experiments are conducted for input angular displacements ranging from 0.002 to 0.016 rad for an input frequency between 10 and 30 Hz. Results highlight the effectiveness of the developed method in capturing the rheological properties under torsion. Variations in the dynamic torsional stiffness suggest the dominant behaviour of the input angular displacement. The bound rubber theory is used to interpret the angular displacement dependent variations on the torsional stiffness. Further, the effect of input frequency and magnetic field on the dynamic torsional stiffness is also examined. It is also observed that the damping capacity of the MRE is dependent on the angular displacement and the dissipation capacity of the elastomer is evaluated in terms of loss factor. Results indicate a significant contribution of the interfacial damping over the intrinsic and magneto-mechanical hysteresis damping. © 2019 IOP Publishing Ltd.Item Dynamic performance of magnetorheological Elastomer isolators for adaptive torsional vibration control in SDoF Systems: An experimental study(Elsevier B.V., 2025) Shenoy, P.; Murthy, A.A.; Gangadharan, K.V.; Patil, I.S.This paper presents an experimental investigation into the application of Magnetorheological Elastomer (MRE) isolators for torsional vibration isolation in a Single Degree of Freedom (SDoF) system. First, the characteristics have been extensively studied under torsional shear, followed by the derivation of the Parametric modeling for the system parameters using a fractional derivative-based Poynting-Thomson model. After investigating the dynamic properties of Magnetorheological Elastomers, an experimental test was custom-built using a MRE isolator for torsional vibration isolation in a single degree of freedom (SDoF) system. The system's input and output angular displacements were measured using the Serial Arrangement of Accelerometers (SAA) technique, which accurately captures the torsional modes of the system. The reduction in the system's transmissibility ratios, a measure of vibration isolation ability, was used to assess the effectiveness of the MRE isolators. The experimental results show that the system's natural Frequency shifts noticeably in response to different magnetic fields, significantly lowering transmissibility ratios. The impact of damping on the system was also investigated despite some discrepancies in the patterns. Results highlight a reduction in the amplitude transmissibility to 37.36 %. Co-relating to the field-dependent increase in the Stiffness, a frequency shift of 3 Hz is also observed. © 2025 The AuthorsItem Performance evaluation of magneto-rheological damper with spring accumulator and on-road testing by implementing in a four wheeler vehicle(Springer, 2025) Puneet, N.P.; Devikiran, P.; Kumar, H.; Gangadharan, K.V.Passenger vehicles running over roads are undergoing speedy updates every now and then in terms of design, luxury and passenger expectations. Above all, a passenger expects greater comfort in a vehicle throughout the journey. In many possible ways, semi-active suspension systems are proving themselves as optimum choice between passive and active systems. The present study emphasizes the performance analysis of a class of semi-active systems called magneto-rheological (MR) dampers. An MR damper suitable for a specific four wheeler vehicle with McPherson suspension system is designed and developed with a spring accumulator. The MR damper thus developed has undergone characterization testing subjected to variable input excitation conditions. The MR fluid for this damper is prepared in the laboratory. Sky-hook and ground-hook controllers are used as the current controlling devices. The developed MR damper is then used in the suspension system of the front half of the four wheeler vehicle for on-road testing. The developed damper showed about 20% improvement in the ride comfort level when used with the control strategies. © Indian Academy of Sciences 2025.