Faculty Publications
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Item Ballistic Impact Study on Jute-Epoxy and Natural Rubber Sandwich Composites(Elsevier Ltd, 2018) Sangamesh, R.; Ravishankar, K.S.; Kulkarni, S.M.Since ages, human beings have used different methods to protect themselves and their armors from the impact of bullets/projectiles by using structures made up of wood, metals, glass and sand bags etc. These protective structures are heavy and incur cost and inconvenience to transport. Of late, they are replaced by structures of polymers and their composites, because of their light weight and good corrosion resistance. Ballistic impact analysis of composite materials is necessary in order to establish their use in military, aerospace and automotive applications either through experimental studies or using modeling techniques. The aim of the present investigation is to model and analyze the behavior of composites for ballistic impact. Residual velocity, energy absorption and ballistic limit for three different materials Jute-Epoxy (JE), Rubber (Ru), Jute-Epoxy-Rubber sandwich (JRE) for three thicknesses (5, 10, 15mm) and at three velocities (150, 250, 350 m/s) is studied. The study exhibits a significant amount of energy absorption in rubber, almost 10 times as compared to JE plate. Also damage observed was ductile in the case of rubber, while brittle in JE. Sandwich composites (JRE) displayed energy absorption and ballistic limit on par with rubber plates. Thus the applicability of these sandwiches in ballistic impact is established as better energy absorbing protective target structures. © 2017 Elsevier Ltd.Item Comparative study on energy absorbing behavior of stiff and flexible composites under low velocity impact(American Institute of Physics Inc. subs@aip.org, 2019) Mahesh, V.; Joladarashi, S.; Kulkarni, S.M.This paper deals with the comparative study on the energy absorbing behaviour of the flexible composites with that of stiff composites aiming at automobile cladding application. Two types of composites namely Jute-Epoxy (JE) laminate and Jute-Rubber-Jute (JRJ) sandwich are chosen for the purpose of study under impact velocity varying from 2.5 m/s to 10 m/s. The study is carried out using commercially available finite element simulation software. The energy absorption and damage behavior of both the composites are studied. From the results, it was found that JRJ sandwich absorbs almost 54%, 51.2%, 58.1% and 61.78% more energy compared to JE laminate for impact velocity of 2.5 m/s, 5 m/s, 7.5 m/s and 10 m/s respectively and exhibits compliant nature as opposed to JE laminate which exhibits brittle nature. The energy absorption ratio of JRJ sandwich is more compared to JE laminate. Thus, the JRJ sandwich composites are expected to provide better energy absorption, reduce damage propagation under low velocity impact, thereby making them a potential material for automobile structural protective claddings. © 2018 Author(s).Item 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.Item Comparative study on kevlar/carbon epoxy face sheets with rubber core sandwich composite for low velocity impact response: FE approach(Elsevier Ltd, 2021) Mahesh, V.; Joladarashi, S.; Kulkarni, S.M.Recent trend has shifted towards replacing the conventional materials by fiber reinforced polymer composites for various structural applications since the fiber reinforced polymer composites exhibit high strength, lighter weight and low cost. This paper work concentrates on analysing the low velocity impact response of two types of sandwich composites namely kevlar epoxy with rubber core (KE-R-KE) and carbon epoxy with rubber core (CE-R-CE) in terms of energy absorption and damage mitigation. Modelling and analysis is carried out by making use of commercially available explicit finite element (FE) software. Results reveal that kevlar based sandwich composite outstands the carbon based composite both in terms of energy absorption by 37.7% and the energy absorption ratio of KE-R-KE is 1.36 times more compared to CE-R-CE sandwich composite. The damage study reveals that both the proposed sandwich composites exhibit similar damage mechanism dominated by matrix cracking followed by fiber breakage and delamination. The presence of rubber as core material helps in mitigating the damage to the bottom facesheet. © 2021 Elsevier Ltd. All rights reserved.Item Thermal degradation and swelling of thermoplastic vulcanizates from NBR/SAN and NBR/Scrap computer plastics blends(Huthig GmbH, 2009) Anandhan, S.; Rajeev, R.S.; De, S.K.; Bhowmick, A.K.Thermoplastic elastomeric blends of nitrile rubber (NBR)/poly(styrene- coacrylonitrile) (SAN) and NBR/scrap computer plastics (SCP) based on acrylonitrile-butadiene-styrene terpolymer (ABS) were prepared. Thermoplastic elastomeric blends of NBR/SAN containing various amounts of a model waste nitrile rubber powder (w-NBR) were also prepared. Thermogravimetric analysis of the above blends was performed in a nitrogen atmosphere. Both Friedman and Flynn-Wall-Ozawa methods were used for the evaluation of activation energies of thermal degradation of these blends. The dynamically vulcanised blends exhibit higher amount of activation energies for thermal degradation than the unvulcanised ones. Swelling studies were performed in various solvents having different solubility parameter values and maximum swelling was found to occur in a solvent having a solubility parameter that was closer to that of the blend components, i.e., around 20MPa1/2. Dynamically vulcan-ised blends show excellent resistance to IRM #903 oil as well as four chosen solvents possessing different solubility parameters (E).Item Modelling, analysis and optimization of adsorption parameters for H3PO4 activated rubber wood sawdust using response surface methodology (RSM)(2009) Helen Kalavathy, M.H.; Iyyaswami, I.; Ganesapillai, M.G.; Miranda, L.R.Adsorption capacity of Cu2+ from aqueous solution onto H3PO4 activated carbon using rubber wood sawdust (RSAC) was investigated in a batch system. Kinetic and isotherm studies were carried out, the thermodynamic parameters like standard Gibb's free energy (?G°), enthalpy (?H°) and entropy (?S°) were evaluated. The pseudo-second-order model was found to explain the kinetics of Cu2+ adsorption most effectively. The process optimization was performed through Central Composite Rotary Design using response surface methodology (RSM) by Design Expert Version 5.0.7 (STAT-EASE Inc., Minneapolis, USA). An initial concentration of 35 mg L-1, temperature of 26 °C, carbon loading of 0.45 g (100 mL)-1, adsorption time 208 min and pH of 6.5 was found to be the optimum conditions for the maximum uptake of copper ions of 5.6 mg g-1 in batch mode. © 2009 Elsevier B.V. All rights reserved.Item Behavior of sandwich beams with functionally graded rubber core in three point bending(2011) Doddamani, M.R.; Kulkarni, S.M.; KishoreThe three-point bending behavior of sandwich beams made up of jute epoxy skins and piecewise linear functionally graded (FG) rubber core reinforced with fly ash filler is investigated. This work studies the influence of the parameters such as weight fraction of fly ash, core to thickness ratio, and orientation of jute on specific bending modulus and strength. The load displacement response of the sandwich is traced to evaluate the specific modulus and strength. FG core samples are prepared by using conventional casting technique and sandwich by hand layup. Presence of gradation is quantified experimentally. Results of bending test indicate that specific modulus and strength are primarily governed by filler content and core to sandwich thickness ratio. FG sandwiches with different gradation configurations (uniform, linear, and piecewise linear) are modeled using finite element analysis (ANSYS 5.4) to evaluate specific strength which is subsequently compared with the experimental results and the best gradation configuration is presented. © 2011 Society of Plastics Engineers.Item Response of fly ash-reinforced functionally graded rubber composites subjected to mechanical loading(2012) Doddamani, M.R.; Kulkarni, S.M.A novel approach to estimate the Young's modulus of a functionally graded rubber composite (FGRC) from the damping ratio is demonstrated with the examples of unreinforced and fly ash-reinforced materials. FGRC coupons were prepared using the conventional casting technique. The occurrence of gradation in the specimens was attributed to the variable density of particles present in the fly ash, settling at different depths. The technique of free vibrations was used for experimentation. The damping response of the FGRC specimens was studied. The results obtained from the experiments showed that, with growing filler weight fraction, the Young's modulus of the composite increased. The empirical model developed to predict the magnitude of the modulus turned out to be in good agreement with experimental data. © 2012 Springer Science+Business Media, Inc.Item Full scale experiment and finite element modeling of support structures of substation equipment for evaluation of ground motion amplification(2012) Nandam, S.; Ramesh Babu, R.; Venkataramana, K.Post earthquake performance of porcelain insulators installed for high voltage substation equipment, in general, revealed their vulnerability to failure, not due to any quality deficiency, but due to failure of their supporting structures. Most of the equipment in standalone state, withstood to tests of induced vibrations conforming to International standards. The same tested equipment, when erected in position over its supporting structure failed to sustain earthquake ground accelerations, as the supporting structure adversely contributed to amplification of the ground seismic motions while traversing to the top of the structure or the base of the insulator. This paper critically examines salutary effects of damping of vibrations on a typical instrument- transformer, using a rubber based elastic damper, with particular reference to the connected porcelain insulators, in partial containment of amplification of earthquake acceleration or in minimizing attendant distress on them. The analytical study carried out is based on experimental studies conducted on the equipment using shake table and then correlating the results obtained using finite element analysis, on the full scale model to draw meaningful conclusions. © 2012 CAFET-INNOVA TECHNICAL SOCIETY.Item Compressive properties of sandwiches with functionally graded rubber core and jute-epoxy skins(2013) Doddamani, M.R.; Kulkarni, S.The compressive behaviour of a new class of sandwich composite made up of jute fiber reinforced epoxy skins and piece-wise linear fly ash reinforced functionally graded (FG) rubber core is investigated in flat-wise mode. FG samples are prepared using conventional casting techniéue. Presence of gradation is éuantified physically by weight method. This paper addresses the effect of weight fraction of fly ash, core to thickness ratio (C/H) and orientation of jute on specific compressive modulus and strength. In each trial five replicates are tested with lower amount of fly ash below the upper skin of sandwich (rubber-up). Results of experimentation are subjected to statistical analysis of variance (ANOVA) to find the influential factor governing the compressive behaviour. Furthermore piece-wise linear gradation is modeled in finite element and strength values are compared with experimental results. Sandwich sample with fly ash content of 40%, C/H of 0.4 and orientations of 30?/60? registered better performance. Specific strength is observed to increase upto 30% filler content followed by stabilization. Finite element results for strength match very well with experimental ones.