Faculty Publications

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    Modelling and analysis of thermomechanical behaviour in composite bimorph actuator
    (Trans Tech Publications Ltd ttp@transtec.ch, 2018) Hiremath, H.; Kulkarni, S.M.
    This paper presents study of a thermomechanical bimorph actuator, constituted by layers of polymer composite material. The proposed bimorph consists of polydimethylsiloxane (PDMS) and carbon black-polydimethylsiloxane (CB-PDMS) polymer composite layered structure. The thermomechanical response of the PDMS and CB-PDMS material is studied. Deflection of bimorph for change in temperature is studied for different thickness and volume percentage of CB bimorph. Three different thicknesses and three volume fractions of CB are used for analysis of bimorph. Deflections of the bimorph are obtained from two different approaches analytical and FE. The modelling of bimorph carried out using multi-physics (FE) software. Results obtained from above approaches are agreeing well with different volume fractions of CB and thickness. It is observed that the bimorph with higher amount of CB has larger deflection. An optimum deflection achieved in an equal layer of bimorph actuators. In this study, the largest displacement noticed at 6 mm thick CB-PDMS layer with 5 Vol% of carbon black filler. © 2018 Trans Tech Publications, Switzerland.
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    Ballistic performance study of kevlar29 fibre reinforced polyester composite
    (Trans Tech Publications Ltd ttp@transtec.ch, 2019) Sangamesh, R.; Hiremath, H.; Ravishankar, K.S.; Kulkarni, S.M.
    Ballistic qualities of the material are important for the military defence barrier application for protection of military persons, their vehicles and equipment. In the present investigation ballistic performance of Kevlar29 fibre reinforced polyester composite (KPC) is analysed. A definite parametric study, taking into account various shape of projectiles (Flat-F, Spherical-S and Conical-C) impact on the composite target of different thicknesses (12, 16 and 20 mm). Impact velocity of the projectile considered for analysis 100-400 m / s. Ballistic parameters such as residual velocity, deformation and penetration behaviour are predicted. Conical projectile has more effect on the composite target compared to other projectile. Composite thickness influenced the energy absorption. The thickness increase from 12 mm to 20 mm which leads to increase in the energy absorption by almost 20%. © 2019 Trans Tech Publications, Switzerland.
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    Optimization of Bilayer Actuator Based on Carbon Black/Polymer Composites
    (Institute of Physics Publishing helen.craven@iop.org, 2019) Hiremath, H.; Sangamesh, R.; Kulkarni, S.M.
    In the last few years, actuators based on polymer composite have been created for incredible potential applications in the zone of artificial muscle, micro-robots, relays, and energy harvesting. Polymer composites show the more massive deflection or bending due to the electrothermal and photothermal efforts. Subsequently, these have excellent orientation on the effect because of material properties and structure. In this study, theoretical modeling is employed to understand and analyze the actuator performance by incorporating carbon black (CB) into the polymer material. Polydimethylsiloxane (PDMS) acts as a polymer matrix with bilayer geometry. The displacement of bilayer polymer composite is identified by the length and thickness of two layers, the distinction of coefficients of thermal expansion (CTE) between bilayer and temperature change are inspected. Theoretical outcome demonstrates that the displacement is enormously affected by the thickness proportion of bilayer actuator. In this manner, it is optimized by upgrading thickness proportion and distinct parameters of the bilayer actuator. Thus, this investigation will give a hypothetical reference to the realistic design and realization of the CB/PDMS composite based on a thermal input. © Published under licence by IOP Publishing Ltd.
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    Study on ballistic characteristics of glass-epoxy-rubber sandwiches
    (Trans Tech Publications Ltd ttp@transtec.ch, 2020) Sangamesh, R.; Hiremath, H.; Ravishankar, K.S.; Kulkarni, S.M.
    This article focuses on the Finite Element (FE) analysis of the ballistic performance of the polymer composites. These composites consisting of natural rubber (NR), glass-epoxy (GE) and glass-rubber-epoxy (GRE) sandwich of different thicknesses (3, 6 and 9 mm) under the impact of the conical nose projectile for a velocity variation of (180, 220 and 260 m / s). FE modeling was carried out to forecast the energy absorption, ballistic limit velocity and failure damage mode of the target material. The significant influence of thickness, interlayers and sandwiching effect was studied: the lowest ballistic limit was obtained for 3 mm thick GE. The energy absorption capacity of GRE sandwich was highest among the natural rubber and GE. The work can be extended for the experimental validation purpose so that these polymer composite materials could be utilized in the defense sector for bullet-proofing. © 2020 Trans Tech Publications Ltd, Switzerland.
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    Analysis of coefficient of thermal expansion in carbon black filled PDMS composite
    (Trans Tech Publications Ltd ttp@transtec.ch, 2020) Hiremath, H.; Sangamesh, R.; Kulkarni, S.M.
    Polymer composites are gaining attention due to their superior thermal properties. Especially carbon black /carbon nanotubes/ graphene filled polymer composites are used in energy harvesting, thermal actuators and MEMS. The coefficient of thermal expansion (CTE) is one of the most important properties in the polymer composite. In the present study, thermal expansion of polydimethylsiloxane (PDMS) matrix is filled with carbon black particle of varied volume fraction is modeled. Two-dimensional finite element (FE) model is computed in order to explain the thermal expansion behavior of the polymer composite and same is carried out for ambient to 70 K temperature. A 2D regular arrangement of circular particle packing model is set up and simulated. The FE model predicts that filler geometry has a little effect on the thermal expansion than the percentage of filler in the composite. Thermal expansion of composite is compared with the theoretical model. It shows that the CTE of composite reduces as the filler percentage increase, also gives good agreement in the both models. Hence, it is found that the addition of carbon black to the polymer composite could make it perform significantly better in thermal expansion. © 2020 Trans Tech Publications Ltd, Switzerland.
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    Modeling and optimization of thermally excited carbon black and polymer composite actuator
    (Elsevier Ltd, 2020) Hiremath, H.; Kulkarni, S.M.
    As of late, actuators in view carbon black, carbon nanotube and graphene were shown in the extraordinary potential application in the field of drug delivery system, relay switches, robotics, energy harvesting and so on. Now a day electro-thermal and photo-thermal driven actuator based on polymer composite show larger actuation compare to the traditional thermal actuator. Though, the impact of structural dimensions and material parameters on the actuator execution ought to be investigated further. Since it is a critical point in the design and fabrications of the high-performance actuator In the present work, finite element (FE) analysis is adopted to simulate the thermally driven bilayer actuator and investigated the performance based on carbon black and polymer composite. Thus, the computational method is carried out to design and optimize the geometry and material parameters such as thickness, the coefficient of thermal expansion and so on. FE simulation results demonstrate that each layer thickness of the actuator has an important role in curvature deformation. A maximum curvature is obtained of 8.9 m-1 by simulation, which is a decent expected value in light of the geometry and material. Furthermore, a larger change in temperature and CTE between two layers additionally predicts the more prominent bending curvature. Consequently, this investigation is relied upon to give a theoretical baseline to plan and fabrication of CB based thermal actuator for a greater actuation performance. © 2018 Elsevier Ltd.
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    Influence of filler on dielectric properties of silicone rubber particulate composite material
    (Elsevier Ltd, 2020) Mathias, K.A.; Hiremath, H.; Manohar Shankar, B.S.; Kulkarni, S.M.
    This paper deals with the development of silicone rubber particulate composites filled with strontium titanate to improve dielectric properties of neat silicone rubber. The composite material is prepared by a solution casting method with three different volume percentages of the filler. The composite samples prepared are tested for dielectric properties as per standards. The influence of filler on dielectric properties of composite material is studied by testing for dielectric permittivity, loss tangent, and ac conductivity. The dielectric permittivity experimentally obtained is compared with the available empirical models. The dielectric permittivity, loss tangent, and ac conductivity of silicone rubber composite increased with the increase of volume percentage of strontium titanate. Compared to neat silicone rubber the dielectric permittivity, loss tangent, and ac conductivity of the silicone rubber composite filled with 10% volume of strontium titanate is increased by 66%, 117%, and 267% respectively. Further, the empirical models confirmed that dielectric permittivity obtained is within the limit. The microscopic study reveals that the improved dielectric properties attributed to the stronger bond between the silicone rubber and the strontium titanate particles. © 2019 Elsevier Ltd. All rights reserved.
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    Investigations on the thermal actuation of carbon black reinforced pdms composite uni-layer and bi-layer cantilever beams
    (ModTech Publishing House office@hotelfloramamaia.ro, 2020) Hiremath, H.; Desai, S.; Kulkarni, S.M.; Karanth P, N.; Desai, V.
    Actuators are the essential components of robots, switches, relays, and many other automatic systems. There are various actuator types based on material, geometry, and stimulus. Nowadays, polymer composite based actuators are gaining importance due to their flexibility, ease of processing, low cost, and easy way of tailoring the properties. Among the polymers, Polydimethylsiloxane (PDMS) is one of the promising polymers for the actuator. In the present study, unilayer and bilayer cantilever beams of PDMS based composite subjected to a thermal stimulus are investigated. The Finite Element (FE) and the analytical models are developed for unilayer and bilayer polymer composite beams and simulated for actuator response. The deflection behavior of these beams is investigated for a temperature input range of 308K to 368K. The beams are analyzed for varying Carbon Black(CB) content from 5 to 25 Vol% in PDMS polymer and beam thickness from 1mm to 5mm. It is observed that with an increasing percentage of filler content, the increment in deflection of the bilayer beam is appreciably higher when compared to the unilayer beam. For 25 Vol% of CB, the bilayer beam shows 11.48 times improvement in deflection value. Also, it is noticed that the thickness of the beams influences deflection more compared to the percentage of the CB content. The deflection of the unilayer and bilayer beam is observed to increase linearly with temperature input. At 368K, the bilayer beam deflection is 6.87 times greater than the unilayer. Hence this analysis is the baseline for predicting the actuator performance of the unilayer and bilayer polymer composite beams considering the set of variables. © International Journal of Modern Manufacturing Technologies.
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    Effect of ketjenblack and barium titanate on the piezoresistive behaviour of silicone rubber particulate composites
    (IOP Publishing Ltd, 2021) Manohar Shankar, B.S.; Hiremath, H.; Kulkarni, S.M.
    In the present study, silicone rubber reinforced with ketjenblack and barium titanate were fabricated using high temperature compression molding method. These particulate composites are characterized for piezoresistive sensitivity. Ketjenblack and barium titanate are the conducting and dielectric fillers in the high temperature vulcanized silicone rubber matrix. The effects of ketjenblack and barium titanate fillers, filler loading, amount of curing agent, curing temperature and mixing time on the piezoresistive properties of these composites were investigated. The piezoresistive sensitivity recorded maximum values of 3.7(10-3) (kPa)-1 for dielectric and dielectric-conductive composites. The linear variation of normalized resistance change was observed for change in pressure up to 20 kPa. The dielectric composite sensitivity increases with reduction in dielectric filler and curing agent loadings, increasing with mixing time and curing temperature. The piezoresistive sensitivity for dielectricconductive composites depends on ketjenblack and barium titanate filler loading. These composites demonstrate interaction effects among the factors. © 2021 The Author(s). Published by IOP Publishing Ltd.
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    Experimental studies on mechanical and dielectric behavior of Glycerol filled Silicone rubber composites
    (IOP Publishing Ltd, 2021) Mathias, K.A.; Hiremath, H.; Kulkarni, S.M.
    In this study, Silicone rubber composites are prepared with Glycerol filler in three different volume fractions. The samples developed are subjected to mechanical and dielectric testing. The tensile strength increases first and later decreases with Glycerol loading whereas compression strength decreases with Glycerol loading. Modulus of elasticity in tension and compression both decreases with the increase of Glycerol loading. Dielectric permittivity, dissipation factor and conductivity are increases with the increase of Glycerol loading. The Silicone Rubber (SR) composite with 15% volume of Glycerol filler shown a maximum reduction in modulus of elasticity of 29% (in tension) and 16.8% (in compression), and maximum improvement in the dielectric permittivity of 112% compared to neat silicone rubber. The reduction in modulus of elasticity with an increase in dielectric permittivity with an increase in Glycerol loading suggests that this material is a potential candidate for materials to be used in soft dielectric sensors and actuator applications. © 2021 IOP Publishing Ltd