Browsing by Author "Mohan Kumar, G.C."

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A detailed study on hybrid plant fibers for packaging applications
(2012) Saravana Bavan, D.; Mohan Kumar, G.C.
Natural fibers are the most economic and usable fibers in upcoming generation of composite industries. They are valid in several applications of automotive sectors, structural field, and packaging industries. The present work is focussed on processing a hybrid plant fiber of vetiver and maize that can be used for packaging industries. The hybrid fiber is processed through Vacuum Assisted Resin Transfer Molding (VARTM) method. The obtained fiber is a biocomposite material of plant fiber and bio resin of epoxodized soya bean oil. The material is tested for mechanical, thermal and morphology properties and it can be summarized that these novel hybrid fibers are good looking and have appreciable properties that can be used for packaging applications. These materials are green and less harm to environment compared to synthetic fibers.
A novel approach to determine the thermal transition of gum powder/hydro-gels using dynamic mechanical analysis
(American Institute of Physics Inc. subs@aip.org, 2018) Nagamadhu, M.; Jeyaraj, P.; Mohan Kumar, G.C.
The dynamic characterization of materials plays a major role in the present area. The many researchers are worked on solid materials and its characterization, it can be tested using dynamic mechanical analyzer (DMA), however, no such work on powder a semiliquid samples. The powder and liquid samples can also easily characterization as like solid samples using DMA. These powder samples are analyzed with a material pocket method which can be used to accurately determine very low levels of variation in powder properties, due to the high sensitivity of DMA to glass transitions. No such DMA studies on hydrogel and Gum powders. The gum powders are used in various applications start from food industries, pharmacy, natural gums paste, biomedical applications etc. among all this applications gum Ghatti is one of the powders using for varies applications. Around 50 milligrams of Ghatti powders are placed inside material pocket and analyzed storage modulus (Gâ€²), loss modulus (Gâ€³) and tan delta (Î´). Also, understand the curing and glass transition effect using water, glycerin and superplastic from room temperature to 200Â°C. The result shows that storage modulus decreases with increase in temperature in pure Ghatti powder. The surprising improvement in storage modulus was found with an increase in temperature with addition of water, glycerin, and superplastic. However, loss modulus and tan delta are also having very significant influence and also shows a clear peak of the tan delta. The loss modulus results were found to be improved by adding solidifying agents, along with this water and superplastic better influence. But glycerine found to be hydrogel in nature and thermodynamic properties are much influenced by frequency. Â© 2018 Author(s).
Acoustic analysis of short areca fiber-reinforced PF composites
(2009) Mohan Kumar, G.C.
In this paper, mechanical properties of the fibers extracted from the dried areca fruit are determined and compared with the other known natural fiber coir. The tensile test of this fiber has indicated that the tensile strength and young's modulus are 110-160 MPa and 2.4GPa respectively. Randomly distributed Areca fibers are reinforced with Phenol Formaldehyde to form composite laminates. Variation of physical properties of these laminates was determined and compared with wood based particle boards. Sound transmission loss measurement has been made using two chamber acoustic measurements Technique. Areca-reinforced composite exhibits an excellent sound absorption compared to plywood. Acoustic analysis of the developed composites shows that areca Composite has good acoustic sound absorption so it is found to be suitable material for acoustic building like theaters, auditoriums, office building factories etc.
Compressive and swelling behavior of cuttlebone derived hydroxyapatite loaded PVA hydrogel implants for articular cartilage
(American Institute of Physics Inc. subs@aip.org, 2018) Kumar, B.Y.S.; Mohan Kumar, G.C.; Isloor, A.M.
Developing a novel antibacterial, nontoxic and biocompatible hydrogel with superior physio mechanical properties is still becoming a challenge. Herein, we synthesize hydroxyapatite (HA) powder from cuttlefish bone and prepare a series of stiff, tough, high strength, biocompatible hydrogel reinforced with HA by integrating glutaraldehyde into PVA/HA. Powder was characterized by SEM and XRD. Compressive strength and swelling properties are studied and compare the results with the properties of healthy natural articular cartilage. Â© 2018 Author(s).
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 Ltd
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 Engineers
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.
Design of sprue bush for a plastic injection mould: A machine perspective
(Association for Machines and Mechanisms, 2013) Lakkanna, M.; Kadoli, R.; Mohan Kumar, G.C.
Design methodology and criteria to configure sprue bush for enhancing functionality is systematically compiled from plastic injection moulding machine perspective. Sprue conduit's sensitivity to moulding objectives are quantitatively ghettoised as expansion ratio on the basis of ubiquitous empirical relationships. This generic, simple, inexpensive preventive criterion enables sprue bush conduit geometry design to exemplifying the melt injection specifically for a particular machine. Continuous Sensitivity Equation Method (CSEM) was adopted to sensitise sprue conduit expansion over infinite dimensional range exclusively for injection rate, maximum injection pressure and barrel size. Inferred results were exponential in nature with injection rate having direct proportionality, while maximum injection pressure and barrel size had inverse proportionality to conduit expansion off parting plane. Off them injection rate was found to be relatively more influential than injection pressure and barrel size.
Dynamic mechanical analysis of glutaraldehyde cross linked polyvinyl alcohol under tensile mode
(American Institute of Physics Inc. subs@aip.org, 2019) Mohan Kumar, G.C.; Jeyaraj, P.; Nagamadhu, M.
Nowadays researchers are looking out for biodegradable materials alternate to petroleum-based materials due to many global issues. Polyvinyl Alcohol (PVA) cross-linked with Glutaraldehyde (GA) polymer have found widespread applications in light-weight structures in replacement of non-biodegradable polymers. The PVA cross-linked with GA polymers were prepared using a conventional compression type molding technique. Dynamic Mechanical Analysis has been carried out to evaluate the tensile storage and loss modulus, tan delta, and elongation, in the temperature range of 25-160Â°C. The results exhibit improvement of thermo-mechanical properties at higher temperatures due to GA crosslinking. Experimental results indicate that the tensile storage and loss modulus were improved due to GA crosslinking. The elongation of PVA-GA decrease considerably with GA crosslinking. The shore D hardness improves with crosslinking up to 20% GA, and further marginal increase in hardness beyond 20% GA crosslinking. Â© 2018 Author(s).
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
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.
Effect of stacking sequence on mechanical properties neem wood veneer plastic composites
(American Institute of Physics Inc. subs@aip.org, 2018) Nagamadhu, M.; Mohan Kumar, G.C.; Jeyaraj, P.
This study investigates the effect of wood veneer stacking sequence on mechanical properties of neem wood polymer composite (WPC) experimentally. Wood laminated samples were fabricated by conventional hand layup technique in a mold and cured under pressure at room temperature and then post cured at elevated temperature. Initially, the tensile, flexural, and impact test were conducted to understand the effect of weight fraction of fiber on mechanical properties. The mechanical properties have increased with the weight fraction of fiber. Moreover the stacking sequence of neem wood plays an important role. As it has a significant impact on the mechanical properties. The results indicated that 0Â°/0Â° WPC shows highest mechanical properties as compared to other sequences (90Â°/90Â°, 0Â°/90Â°, 45Â°/90Â°, 45Â°/45Â°). The Fourier Transform Infrared Spectroscopy (FTIR) Analysis were carried out to identify chemical compounds both in raw neem wood and neem wood epoxy composite. The microstructure raw/neat neem wood and the interfacial bonding characteristics of neem wood composite investigated using Scanning electron microscopy images. Â© 2018 Author(s).
Effect of TiC addition on fracture toughness of Al6061 alloy
(American Institute of Physics Inc. subs@aip.org, 2018) Raviraj, M.S.; Sharanaprabhu, C.M.; Mohan Kumar, G.C.
Al 6061 matrix was reinforced with different proportions of TiC particles such as 3wt%, 5wt% and 7wt% and the effect on fracture toughness was studied. Al-TiC metal matrix composites were produced by stir casting method to ensure uniform distribution of the TiC particulates in the Al matrix. LEFM (Linear Elastic Fracture Mechanics) has been used to characterize the fracture toughness using various specimen geometries. The compact tension (CT) specimens with straight through notch were machined as per ASTM E399 specifications. All the specimens were machined to have constant a/W=0.5 and B/W was varied from 0.2 to 0.7. A sharp crack initiation was done at the end of notch by fatigue loading using servo-hydraulic controlled testing machine. Load v/s crack mouth opening displacement (CMOD) data was plotted and stress intensity factor, KQ determined. Critical stress intensity factor KIC was obtained by plotting KQ v/s thickness of specimen data. The fracture toughness of the composites varied between 16-19 MPaâˆšm as compared to 23MPaâˆšm for base alloy Al6061. Composites with 3wt% and 7wt% TiC showed better fracture toughness than 5wt% TiC reinforced Al metal matrix composites. Â© 2018 Author(s).
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.
Functionally graded bio-ceramic reinforced PVA hydrogel composites for knee joint artificial cartilages
(American Institute of Physics Inc. subs@aip.org, 2018) Mohan Kumar, G.C.
Research progress in materials science for bio-based materials for cartilage repair or supportive to host tissue has become a fashionable, worldwide. Few efforts in biomedical engineering has attempted in the development of newer biomaterials successfully. Bio ceramics, a class of materials been used in particulate form as a reinforcement with polymers those ensure its biocompatibility. Every artificial biomedical system has to meet the minimum in Vitro requirements for successful application. Equally the biological behavior of normal and diseased tissues is also essential to understand the artificial systems to human body. Â© 2018 Author(s).
Influence of textile properties on dynamic mechanical behavior of epoxy composite reinforced with woven sisal fabrics
(Springer, 2020) Nagamadhu, M.; Jeyaraj, J.; Mohan Kumar, G.C.
Due to low cost and environmentally friendly characteristics, natural fibers gain much attention over synthetic fiber. The aim of the present work is to characterize the textile properties of three different types of sisal fabric and study dynamic mechanical properties and water absorption behavior of the sisal fabric reinforced epoxy composite. Influence of grams per square meter of fabric, weaving pattern of the fabric on textile properties of the fabric is studied first. Further, the effect of the same on the dynamic mechanical properties of the sisal composites is studied. Effect of fiber weight percentage and dynamic frequency on dynamic mechanical properties also studied. Results reveal that the storage modulus (G?) decreases with increasing temperature in all the woven types of composites under consideration. However, Plain 2 (P2) and Weft Rib (WR) composites have shown better values of G? even after the glass transition temperature (Tg). From the results, it is also evident that storage and loss modulus (G??) increases when the yarn diameter decreases which is observed at a higher temperature also. It is also observed that fabric density also plays a significant role in the enhancement of G? and G?? values. The water absorption of Plain 1 (P1) based composites are found to be less compared to the other types of composites analyzed. © 2020, Indian Academy of Sciences.
Leveraging the effectiveness of hybrid metal-fiber composites in high speed rotating machines
(American Institute of Physics Inc. subs@aip.org, 2019) Gonsalves, T.H.; Mohan Kumar, G.C.; Ramesh, M.R.
Fiber metal composites made up of alternative layers of metallic and composite are now widely used in Aircraft structures are result of one such effort which bring in the combined strengths of composites and metals. In a similar way, the use of metal fiber composites made up of composite material laminates sandwiched between metallic sheets firmly bonded with high quality adhesives can become an effective replacement of conventional metallic components in high speed machinery such as gas turbines. The benefits of this hybrid form of composite material has the potential of use in areas where fiber reinforced composite material cannot be directly exposed due to the harsh environment of gas turbines. In addition, the metallic surfaces can easily interface into their respective metallic assemblies. Such hybrid composite materials used in static structures can push some of the structural natural frequencies beyond the operating speeds. Composite material used in supporting structures can effectively dampen the excessive vibrations and to further improve the damping capacity the viscoelastic material can also be strategically inserted between the layers. In rotating systems hybrid composite material can be used for some of the long slender shafts to push the critical speeds away from the operating speeds. But unlike supporting structures the damping present in the composite material can induce rotor dynamic instability of rotor-bearing systems. Hence the right combination of metal and fiber reinforced composites can effectively avoid or place the resonances and drastically reduce the vibrating stresses to improve the overall fatigue life of rotating machinery. Â© 2018 Author(s).
Low cost cpm machine for knee joint
(2012) Metan, S.S.; Krishna, P.; Mohan Kumar, G.C.
In today's world of industrialization, no single branch of Engineering and Technology can be considered independently. In order to increase productivity and profitability, industrial products are designed with the technology involving Mechanical and Electronics principles i.e. Mechatronics. Mechatronics has a vital importance in various fields such as agricultural, aviation, automobile, medical, etc. The scope of present work is to design, manufacture and test the low cost knee Continuous Passive Motion (CPM) machine. By using motorized device of CPM machine, we can gradually move the knee joints. This is not possible actively to the patient due to pain. The knee joint motion without patient's muscular effort is called as passive motion. The machine designed and developed in present work can achieve this. Once the patient is able to use his muscular power for his active joint motion, CPM is no longer medically necessary. In the present work, design and manufacturing of the Low Cost Knee CPM machine has been successfully done and is elaborated. The machine was manufactured and tested at one of the renowned Hospitals in Sholapur-India. The patient is exercised on CPM machine for three weeks and is observed to be improved to normal condition i.e. normal Range of Motion (ROM). Â© (2012) Trans Tech Publications, Switzerland.
Machinability studies of low alloy steels by face turning method: An experimental investigation
(Elsevier Ltd, 2013) Lalbondre, R.; Krishna, P.; Mohan Kumar, G.C.
The present study is an experimental investigation on machinability of two low alloy steels, AISI 9320 and AISI 4340, by face turning method. The face turning method makes use of cylindrical steel specimen as a test piece and a triangular P-30 insert as a cutting tool for testing the machinability. The effectiveness of this method is assessed by studying: the cutting time required for the tool to reach flank wear up to 0.3mm (tool life criterion); tool wear development and wear mechanisms involved in machining; tool life studies and machinability indices of the work-material; surface roughness investigations of the machined surfaces; and chip morphology. The machinability tests undertaken in the current investigation follows some of the guidelines indicated in the international standards, ISO 3685:1993(E) and American Foundry Society (AFS) standard machinability tests. The results presented here demonstrate the ability of the face turning method: to evaluate the tool wear development and tool life studies; to rank the work material according to their machinability, to investigate surface roughness due to tool wear; to investigate chip morphology with crater wear and to characterize the machinability of steels under consideration. The face turning method used here is simple and effective for the given tool-work material pair. Â© 2013 The Authors. Published by Elsevier Ltd.
Maize–natural fiber as reinforcement with polymers for structural applications
(Apple Academic Press, 2012) Saravana Bavan, D.; Mohan Kumar, G.C.
Thermosetting resins are used today with plant fiber for panels suitable for inner door panels for the automotive industry and other applications in structures. The costs of these resins are low compared to thermoplastic resins and also the properties of the resin are well suited for structural application (Wool and Sun, 2005). Recently lot of research has been carried out on natural fibers using resin transfer molding (RTM) as a processing method of composites. Dynamic mechanical properties of sisal based natural fibers reinforced with polyester were investigated using RTM (Sreekumar, 2009, 2009a). Vacuum assisted resin transfer molding (VARTM) techniques have been developed for fabricating small and large components but mainly for complex shapes. It also gives good surface finish to the particular part. It is best suited for low cost components of complex part which should be pressurized by external source. It uses atmospheric pressure as a clamp to hold the laminates together. © 2012 by Apple Academic Press, Inc.