Faculty Publications
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Item Study on Mechanical & Cryogenic Properties of Carbon Epoxy Composites(Institute of Physics Publishing helen.craven@iop.org, 2018) Sunil Kumar, B.V.; Neelakantha, N.V.; Surendranathan, A.O.; Anilas, K.Carbon-fiber-reinforced polymers are composite materials. In this case the composite consists of two parts: a matrix and reinforcement. In CFRP the reinforcement is carbon fiber which provides the strength. The matrix is usually a polymer resin such as epoxy to bind the reinforcements together. The material properties depend on these two elements. The reinforcement will give the CFRP its strength and rigidity measured by stress and elastic modulus respectively. Unlike isotropic materials like steel and aluminium CFRP has directional strength properties. The properties of CFRP depend on the layouts of the carbon fiber and the proportion of the carbon fibers relative to the polymer. This paper deals with the studies done on cryogenic treatment (Liquid Nitrogen) of composites having different fiber and matrix composition. In this work studies are done to find the effects caused by the liquid nitrogen on composites mechanical properties and change in properties due to different fiber and matrix composition in composites. It was observed that due to cryogenic treatment there was changes in the physical properties of the specimens. The specimens had deformed in their shape. The more deformation was seen in 60:40 specimen which was treated for 48 hrs and tensile strength of the composites at cryogenic temperature had higher values than that normal temperature for 70:30 specimen which was treated for 24hrs. The flexure strength of the composites at cryogenic temperature had higher values than the normal temperature for all the specimens. The flexure strength is more for 70:30 specimen which was treated for 48hrs. © Published under licence by IOP Publishing Ltd.Item Experimental analysis on effect of various fillers on mechanical properties of glass fiber reinforced polymer composites(American Institute of Physics Inc. subs@aip.org, 2019) Aveen, K.P.; Bhajantri, V.; D'Souza, R.; Neelakantha, N.V.; Jambagi, S.Filler materials are the inert materials which are used in glass fiber reinforced polymer (GFRP) composites for modifying the chemical and physical properties of the matrix polymers to reduce material costs, to improve processability, to improve product performance or to simply act as extenders or matrix diluents. Effect of fillers on mechanical properties like tensile strength, flexural strength, tensile modulus, impact strength, hardness was tested by various methods experimentally. The present work focused on fabrication of Glass Epoxy composite with Mother of pearl, fly ash and aluminum powder used as filler material. The Filler material was varied in % composition by 3%, 6% and 9% in the total volume. This study was carried in order to determine the mechanical properties of fabricated composite by conducting Tensile and Flexural tests. The tests showed the composite with aluminum filler material exhibits better tensile property and composite with fly ash filler exhibits better flexural property. © 2018 Author(s).Item Study on fracture toughness of carbon-carbon composites at low temperatures(Elsevier Ltd, 2022) Sunil Kumar, B.V.S.; Neelakantha, N.V.; Kumar, M.; Lokesha, M.; Vasantha Kumar, S.N.; Surendranathan, A.O.Carbon-carbon composites (C-CC), employed as composites in space and other industries for their outstanding properties. In extreme temperatures, the C-CC has proved to be the most efficient material. C-CC is one of the top thermal quality high-temperature materials such as high-temperature stability, excellent thermal conductivity, and low-temperature expansion coefficients. C-CC brake disks are highly demanded in aviation, trains, trucks, even race vehicles. Although C-CC is normally utilized at very high service temperatures, recently it has been necessary to explore these in low-temperature circumstances as components must also pass through low-temperature conditions in modern applications. In developing engineering structures, materials and systems for their technical safety, durability, and reliability, fractures and damage prevention and evaluation have an important role to play. Fracture toughness means quantifying the resistance of the fracture when a crack occurs. The present experimental study explores the influence of low temperature on the fracture toughness of C-CC. The low temperatures test of the samples has been done at a temperature between -10 °C and -40 °C. The results demonstrate that the fracture toughness value consistently raised as the temperature dropped. The Fluctuation began at a -10 °C from 2 % with a forecast of -40 °C to 32 %. © 2022 Elsevier Ltd. All rights reserved.Item Carbon-carbon composites by preformed yarn method(2011) Naik, P.; Neelakantha, N.V.; Surendranathan, A.O.; Jayaraju, T.The conventional techniques of manufacturing carbon-carbon(C/C) composites have reportedly encountered problems because the resulting C/C composites exhibit non-uniform properties such as bending strength and density. A novel method of manufacturing C/C composites by preformed yarns (PY) is used. The matrix powder consists of coke powders and the binder. The preformed yarn contains the matrix powders inside the carbon fiber bundle and coated on circumference with nylon-6 polymer. This preformed yarn is then chopped and hot pressed at about 600°C to get bars and pellets. These are again heat treated at 1500°C and further impregnated by one more pitch cycle, again heat treated at 2200°C. The tests for hardness, compression strength, Creep strength, resistance to oxidation, and fracture toughness are conducted on these pellets and bars. The micostructural analysis in SEM is done. These tests reveal that the properties obtained from PY method are superior to the properties obtained from any other conventional method.Item Influence of Precracking Techniques on Fracture Toughness of Carbon-Carbon Composites(Penerbit UTHM, 2021) Sunil Kumar, B.V.S.; Neelakantha, N.V.; Lokesha, M.; Surendranathan, A.O.Abstract: Carbon-Carbon composites are one such material which give designers significant importance for advanced applications over conventional materials. The remarkable characteristics of carbon-carbon composites had made these products initially extremely useful in the field of aerospace and defense applications. Now, they are presently used in many applications such as biomedical implants, glass, and high temperature glass, etc. In material science, fracture toughness is a trait that depicts the ability of a material to withstand fractures and is one of the most important features in many design applications of any material. A precracked specimen is a sample that is used to accurately assess the distribution of cracks and it is a favored method. This paper describes a comparison of four precracking techniques for carbon-carbon composites using SENB specimen. The potential implications of these techniques on fracture toughness values have been evaluated. The outcome of this work indicates that precracking with a jewel saw is recommended over the other techniques. © 2021. UTHM Publisher. All rights reserved.