Faculty Publications
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Item Dynamic deformation–dependent magnetic field–induced force transmissibility characteristics of magnetorheological elastomer(SAGE Publications Ltd info@sagepub.co.uk, 2017) Poojary, U.R.; Hegde, S.; Gangadharan, K.V.The need for broad-band vibration isolation performance of the structures is fulfilled by magnetorheological elastomer–based smart vibration isolation system. The smart isolation capabilities of magnetorheological elastomer isolator vary with the input dynamic deformation levels. In this study, force transmissibility measurement approach is adapted to evaluate the influence of dynamic deformation on the field-induced isolation capabilities of magnetorheological elastomer. The variation in isolation capabilities of magnetorheological elastomer is assessed in terms of isolation effect. Isolation performance of magnetorheological elastomer is enhanced with the increase in the magnetic field. Under increased dynamic deformation levels, the isolation characteristics of magnetorheological elastomer are influenced by the Payne effect. Dominance of the Payne effect under non-magnetized state of magnetorheological elastomer has enhanced the isolation effect at larger strain levels. The influence of strain on isolation characteristics of magnetorheological elastomer is verified from the magnetic force simulation between a pair of dipoles performed in ANSYS (version 14). © 2016, © The Author(s) 2016.Item Experimental investigation on the effect of carbon nanotube additive on the field-induced viscoelastic properties of magnetorheological elastomer(Springer New York LLC barbara.b.bertram@gsk.com, 2018) Poojary, U.R.; Hegde, S.; Gangadharan, K.V.The additives improve the properties of magnetorheological elastomer by modifying the surface of ferromagnetic filler particles or by varying the properties of a host polymer matrix. In this study, effect of carbon nanotube additive on the viscoelastic properties of magnetorheological elastomer reinforced with optimum quantity of ferromagnetic filler is studied. Room temperature vulcanizing silicone elastomer-based test samples are prepared by mixing the elastomer with the carbon nanotube and carbonyl iron powder blend obtained from ultrasonication. Viscoelastic properties are measured by adopting the dynamic blocked transfer stiffness method. The results revealed that the properties of magnetorheological elastomer vary significantly with the inclusion of carbon nanotube. With the addition of 0.5 wt% carbon nanotube, the zero field dynamic stiffness of magnetorheological elastomer is enhanced by 36.7% and the loss factor is increased by 17.2%. The enhancement in zero field properties led to the least field-induced enhancement for magnetorheological elastomer doped with 0.5 wt% carbon nanotube. A relatively larger flexibility of pure magnetorheological elastomer samples had resulted in the maximum field-induced enhancement of 48.04%. Among the prepared test samples with carbon nanotube addition, the sample loaded with 0.25 wt% carbon nanotube exhibited a pronounced stiffness enhancement and lower loss factor. This substantiated the existence of an optimum limit for carbon nanotube additive. The present study also confirmed the feasibility of developing MRE tailor-made to suit the particular application by selecting a proper composition of matrix, filler and the additives. © 2017, Springer Science+Business Media, LLC, part of Springer Nature.Item Material modeling of frequency, magnetic field and strain dependent response of magnetorheological elastomer(Springer, 2021) Poojary, U.R.; Gangadharan, K.V.Accurate modeling of material behavior is very critical for the success of magnetorheological elastomer-based semi-active control device. The material property of magnetorheological elastomer is sensitive to the frequency, magnetic field and the input strain. Additionally, these properties are unique for a particular combination of matrix and the filler loading. An experimental-based characterization approach is costly and time consuming as it demands a large amount of experimental data. This process can be simplified by adopting material modeling approach. The material modeling of magnetorheological elastomer is an extension of conventional viscoelastic constitutive relations coupled with hysteresis and magnetic field sensitive attributes. In the present study, a mathematical relation to represent the frequency, magnetic field and strain dependent behavior of magnetorheological elastomer is presented. The viscoelastic behavior is represented by a fractional zener element and the magnetic field and strain dependent attributes incorporated in the model by a magnetic spring and linearized Bouc-–Wen element, respectively. The proposed model comprised of a total of eight parameters, which are identified by minimizing the least square error between the model predicted and the experimental response. The variations of each parameter with respect to the operating conditions are represented by a generalized expression. The parameters estimated from the generalized expression are used to assess the ability of the model in describing the dynamic response of magnetorheological elastomer. The proposed model effectively predicted the stiffness characteristics with an accuracy, more than 94.3% and the corresponding accuracy in predicting the damping properties is above 90.1%. This model is capable of fitting the experimental value with a fitness value of more than 93.22%. © 2021, The Author(s).