Journal Articles
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Item Morphological and thermal properties of maize fiber composites(Korean Fiber Society, 2012) Saravana Bavan, D.; Mohan Kumar, G.C.Maize stalk has become one of the major sources of fibers from the agricultural residues. Use of these fibers as a reinforcement in the polymer is described in this paper. The present work is focused on establishing the properties such as physical, chemical, morphological structure and thermal properties of maize stalk fiber using different characterization techniques. Simple hand layup method was followed for processing the composite material. Chemical treatments of fibers were carried out to study the interaction of fibers with the matrix. The results revealed that maize fibers can also be used as a traditional fiber as reinforcement in a natural fiber reinforced composite materials. © 2012 The Korean Fiber Society and Springer Science+Business Media Dordrecht.Item Methodological and parametric studies of machinability of carbon and alloy steels(2013) Lalbondre, R.; Krishna, P.; Mohan Kumar, G.C.The carbon and alloy steels form an increasingly diverse variety and range of steels in manufacturing industries. The assessment of the machinability of an engineering material becomes a matter of prime activity to improve productivity. The machinability of carbon and alloy steels is affected by many factors, such as the composition, microstructure, and strength level of the steel; the feeds, speeds, and depth of cut; and the choice of cutting fluid, cutting tool material and its geometry. Thus the machinability is an intrinsic technological property which is complex to understand and difficult to determine. This paper discusses different methodology of determining the machinability and its rating/index. One of the methodologies, the face turning method in particular, shall be used to determine the machinability of carbon and alloy steel. Further it deals with identifying the appropriate cutting parameters to test the machinability in an effective, simple and easy way. The research work findings here provide useful economic machining solution of knowing, in advance, the machinability of steels to gain and maintain a competitive advantage. © 2013 CAFET-INNOVA TECHNICAL SOCIETY.Item Computational design of mould sprue for injection moulding thermoplastics(Society for Computational Design and Engineering info@idsociety.org, 2016) Lakkanna, M.; Mohan Kumar, G.C.; Kadoli, R.To injection mould polymers, designing mould is a key task involving several critical decisions with direct implications to yield quality, productivity and frugality. One prominent decision among them is specifying sprue-bush conduit expansion as it significantly influences overall injection moulding; abstruseness anguish in its design criteria deceives direct determination. Intuitively designers decide it wisely and then exasperate by optimising or manipulating processing parameters. To overwhelm that anomaly this research aims at proposing an ideal design criteria holistically for all polymeric materials also tend as a functional assessment metric towards perfection i.e., criteria to specify sprue conduit size before mould development. Accordingly, a priori analytical criterion was deduced quantitatively as expansion ratio from ubiquitous empirical relationships specifically a.k.a an exclusive expansion angle imperatively configured for injectant properties. Its computational intelligence advantage was leveraged to augment functionality of perfectly injecting into an impression gap, while synchronising both injector capacity and desired moulding features. For comprehensiveness, it was continuously sensitised over infinite scale as an explicit factor dependent on in-situ spatio-temporal injectant state perplexity with discrete slope and altitude for each polymeric character. In which congregant ranges of apparent viscosity and shear thinning index were conceived to characteristically assort most thermoplastics. Thereon results accorded aggressive conduit expansion widening for viscous incrust, while a very aggressive narrowing for shear thinning encrust; among them apparent viscosity had relative dominance. This important rationale would certainly form a priori design basis as well diagnose filling issues causing several defects. Like this the proposed generic design criteria, being simple would immensely benefit mould designers besides serve as an inexpensive preventive cliché to moulders. Its adaption ease to practice manifests a hope of injection moulding extremely alluring polymers. Therefore, we concluded that appreciating injectant?s polymeric character to design exclusive sprue bush offers a definite a priori advantage. © 2015 Society of CAD/CAM EngineersItem Sea coral-derived cuttlebone reinforced epoxy composites: Characterization and tensile properties evaluation with mathematical models(SAGE Publications Ltd info@sagepub.co.uk, 2016) Periasamy, K.; Mohan Kumar, G.C.Using sea coral as a new bio-mass in processing of particle-filled polymer composites is very promising in the field of structural applications. In this study, waste cuttlebone was used as a filler material in epoxy composites. In general, cuttlebone particles derived from crushing and sieving were in aragonite polymorph form. In the present study, calcite polymorph form was obtained after heat treatment of cuttlebone particles at 400°. Presence of polymorph form, elemental composition and thermal stability were confirmed with different characterization techniques. Composites were prepared with aragonite and calcite polymorph form cuttlebone particles and commercially available calcium carbonate as reinforcement in epoxy matrix. Tensile tests were carried out to determine the composites strength and compared with predefined theoretical models. Heat-treated cuttlebone reinforced epoxy composites showed higher tensile properties and better interaction between filler and matrix than other composites. © SAGE Publications.Item Experimental investigation of effect of specimen thickness on fracture toughness of Al-TiC composites(Gruppo Italiano Frattura, 2016) Raviraj, M.S.; Sharanaprabhu, C.M.; Mohan Kumar, G.C.In this paper, the macro and micro-mechanical fracture behavior was studied for aluminum (Al6061) alloy matrix, reinforced with various proportions of TiC particles such as 3wt%, 5wt% and 7wt%. The Al6061-TiC metal matrix composites were produced by stir casting method to ensure uniform distribution of the TiC particulates in the Al matrix. The compact tension (CT) specimens were machined according to ASTM E399 specifications to evaluate the fracture toughness for Al6061-TiC metal matrix composites. The CT specimens were machined for crack to width (a/W) ratio of 0.5 and thickness to width (B/W) ratios of 0.2 to 0.7 with an increment of 0.1. Load versus crack mouth opening displacement (CMOD) data was plotted to estimate stress intensity factor KQ for various thicknesses of the specimen. The fracture toughness KIC was obtained by plotting stress intensity factor versus thickness to width ratios of specimen data. The fracture toughness of these composites varied between 16.4-19.2 MPa?m. Scanning Electron Microscope (SEM) studies was made on the fractured surface of the specimens to understand the micro-mechanisms of failure involve in these composites. Void initiation is more significant in the matrix near the interface. The micro-cracks grow from these micro-voids and crack propagates by linking these micro cracks locating the crack path preferentially in the matrix adjacent to the interface indicating ductile fracture. © 2016, Gruppo Italiano Frattura. All rights reserved.Item Design and development of microneedle array-based electrode for bio-potential measurement(Inderscience Publishers, 2017) Balashanmugam, N.; Naveen, K.; Krishna, K.; Mohan Kumar, G.C.Conventional wet electrodes used in bio-potential measurement like EEG, ECG, etc., require the need for conductivity gel application on skin to wet the surface so that more contact area exist between skin and electrode resulting in better signal acquisition. Wet electrodes have certain drawbacks like the gel tends to underperform within one to two hours after application due to reasons like body heat. To overcome this drawbacks, dry electrodes are being developed which can be classified into two types; one penetrating skin and the other not. Both this type of electrodes has the advantages and limitations. The major drawback of filament type non-penetrating dry electrodes is that if the interest is in acquiring signals during motion, these electrodes tend to move relative to the skin resulting in noisy signal where as the microneedle can overcome this drawback by being continuously in contact with skin in all circumstances. In present work we have used micromachining technique to fabricate PMMA microneedle array. The study involves design of microneedle array, fabrication and mechanical testing of microneedles for skin insertion. It was found that for skin insertion upto 150 ?m microneedles 7.5 N load was required and microneedles were structurally stable at this load. © © 2017 Inderscience Enterprises Ltd.Item Effect of specimen crack lengths on stress intensity factor for Al6061-TiC composites using experimental and 3D numerical methods(Emerald Group Publishing Ltd. Howard House Wagon Lane, Bingley BD16 1WA, 2017) Raviraj, M.S.; Sharanaprabhu, C.M.; Mohan Kumar, G.C.Purpose-The purpose of this paper is to present the determination of critical stress intensity factor (KC) both by experimental method and three-dimensional (3D) finite element simulations. Design/methodology/approach-CT specimens of different compositions of Al6061-TiC composites (3wt%, 5wt% and 7wt% TiC) with variable crack length to width (a/W0.3-0.6) ratios are machined from as-cast composite block. After fatigue pre-cracking the specimens to a required crack length, experimental load vs crack mouth opening displacement data are plotted to calculate the KC value. Elastic 3D finite element simulations have been conducted for CT specimens of various compositions and a/W ratios to compute KC. The experimental results indicate that the magnitude of KC depends on a/W ratios, and significantly decreases with increase in a/W ratios of the specimen. Findings-From 3D finite element simulation, the KC results at the centre of CT specimens for various Al6061-TiC composites and a/W ratios show satisfactory agreement with experimental results compared to the surface. Originality/value-The research work contained in this manuscript was conducted during 2015-2016. It is original work except where due reference is made. The authors confirm that the research in their work is original, and that all the data given in the article are real and authentic. If necessary, the paper can be recalled, and errors corrected. © Emerald Publishing Limited.Item Compressive behavior of cenosphere/epoxy syntactic foams in arctic conditions(Elsevier Ltd, 2018) Shahapurkar, K.; Garcia, C.D.; Doddamani, M.; Mohan Kumar, G.C.; Prabhakar, P.In this paper, the effects of arctic condition on the compressive response of ceno-sphere/epoxy syntactic foams are investigated. Understanding the behavior of such foams under extreme conditions is critical for exploring their suitability for constructing lightweight platforms used in arctic explorations, which are exposed to subzero temperatures for extended periods of time potentially degrading their mechanical properties. In the research study presented here, samples of cenosphere/epoxy syntactic foams were conditioned under arctic environment at a temperature of ?60 °C for a period of 57 days. Compression tests were then conducted at room temperature as well as in-situ ?60 °C on the conditioned samples and compared against unconditioned samples tested at room temperature. Combinations of surface modification and cenosphere volume fractions were considered. For the case of unconditioned samples, compressive strength decreased with increasing cenosphere volume fraction for both surface modified and unmodified cenospheres. For the arctic conditioned samples, cenospheres/epoxy foams did not present visible signs of degradation prior to testing, but manifested a reduction in compressive modulus in a range of 47–57% and 47–65% for untreated and treated cenospheres/epoxy syntactic foams as compared to their unconditioned counterparts. On the other hand, the compressive strength increased in a range between 32–68% for untreated and 59–80% for treated cenosphere foams in arctic environment, which can be attributed to the matrix hardening introduced by frigid in-situ environment. Also, under in-situ arctic compressive loading, the post peak response for all foam types have shifted from a progressive failure to a brittle type behavior. © 2017 Elsevier LtdItem Mechanical and tribological behavior of woven sisal fabric(Faculty of Engineering, University of Kragujevac tribology@fink.rs Sestre Janjic 6 Kragujevac 34000, 2019) Nagamadhu, M.; Jeyaraj, P.; Mohan Kumar, G.C.A study has been carried out to investigate the Mechanical and Tribological Properties of Woven Sisal Fabric. Two Plain fabrics were prepared by changing gram per unit area (GSM), and one weft rib fabric is prepared to understand the effect of woven structure on mechanical and wear properties. These fabrics textile properties were determined as per textile ASTM standards. The tensile properties of these fabrics were studied in both warp and weft directions. Further, pilling resistance, abrasion resistance and wear properties of these fabrics were studied using L27 Taguchi Orthogonal Array. The tensile properties were found to be better in weft direction as compared to warp direction in all type of fabrics. The pilling resistances were found better in weft rib fabrics. The abrasion resistance is exhibited better at higher GSM. From the results, it also reveals that higher the crimp value more the resistance against adhesion wear using Pin on disk method. More the yarn linear density more the resistance for adhesion wear. However, the wear load, woven pattern and traveling distance have a significant impact on weight loss and frictional force. © 2019 Published by Faculty of Engineering.Item Effect of cenosphere filler surface treatment on the erosion behavior of epoxy matrix syntactic foams(John Wiley and Sons Inc. cs-journals@wiley.com, 2019) Shahapurkar, K.; Doddamani, M.; Mohan Kumar, G.C.; Gupta, N.Influence of cenosphere surface modification and volume fraction on the solid particle erosion of cenosphere/epoxy syntactic foams is investigated. Fly ash cenospheres are used as filler in both as received and silane surface modified configurations. Erosion behavior is studied at room temperature for different impact angles (30, 45, 60, and 90°) and velocities (30, 45, and 60 m/s). Neat epoxy shows the highest erosion rate compared with that of the syntactic foams. Results show a strong dependence of impact angle and velocity on erosion rate of syntactic foams. With increasing cenosphere content erosion rate decreases for all impact angles. Erosion rate decreases with increasing impact angle and with decreasing velocity. Good interfacial bonding of treated cenospheres enhances the erosion resistance. All the samples exhibit ductile erosive behavior, with maximum erosion at 30°. The velocity exponent and erosion efficiency parameters confirm the ductile behavior of syntactic foams. POLYM. COMPOS., 40:2109–2118, 2019. © 2018 Society of Plastics Engineers. © 2018 Society of Plastics Engineers