Faculty Publications

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    Multi-objective optimisation of cryogenic turning process using Taguchi-based grey relational analysis
    (Inderscience Publishers, 2017) Sivaiah, P.; Dupadu, D.
    Cryogenic machining is a sustainable manufacturing approach; it eliminates coolant disposal cost, health problems compared to the conventional flood cooling. The present study investigates the multiple response optimisation of turning process while machining AISI 17-4 PH stainless steel under the cryogenic environment (jetting of liquid nitrogen at -196°C at the rake face of the tool) by using Taguchi-based grey relational analysis. The optimum levels of the machining parameters are cutting speed at 120.89 m/min, feed rate at 0.048 mm/rev, depth of cut 0.4 mm and physical vapour deposition (PVD) AlTiN coated tungsten carbide (WC). Taguchi-based grey relational analysis method reduced the cutting forces by 7.75%, improved the surface finish by 55.87%, and increased the material removal rate (MRR) by 154.76% and 25% increased the tool flank wear in cryogenic turning process. From the analysis of variance, it was identified that feed rate is the most influenced process parameter on turning performance characteristics. © © 2017 Inderscience Enterprises Ltd.
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    Assessment of spatiotemporal heat flux during quenching in TiO2 and AlN nanofluids
    (ASTM International, 2017) Nayak, U.V.; Ramesh, G.; Prabhu, K.N.
    In the present work, spatiotemporal heat flux transients were estimated during quenching of an Inconel 600 alloy probe in water-based titanium dioxide (TiO2) and aluminum nitride (AlN) nanofluids that have nanoparticle concentrations varying from 0.001 to 0.5 vol. %. The results showed reduced peak heat flux and a longer vapor phase stage during quenching with nanofluids compared to quenching with water. The peak heat flux for quenching in nanofluids was lowered with increase in the nanoparticle concentration. Quenching with TiO2 nanofluids resulted in slower heat extraction compared to quenching in AlN nanofluids at higher concentrations. Quenching with nanofluids resulted in a more uniform quench compared to quenching with water because of the reduction in the rewetting period. © © 2017 by ASTM International.
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    Experimental and 3D FE evaluation of crack initiation energy J 1C in Al6061-TiC composites
    (IOS Press Nieuwe Hemweg 6B Amsterdam 1013 BG, 2018) Raviraj, M.S.; Sharanaprabhu, C.M.; Mohan Kumar, G.C.M.
    The test data crack initiation energy in Mode-I fracture, J 1C is determined experimentally for various compositions of Al6061-TiC composites by using compact tension (CT) specimen with variable aW ratios. Also, 3D nonlinear (elastic-plastic) finite element analysis was carried for Compact Tension (CT) specimen to evaluate J 1C, ahead at the crack-front of several Al6061-TiC composite specimens with various crack lengths. The 3D FEA J 1C results were compared with the experimental results. The J 1C values decrease with increasing crack length of the specimen because of decrease in load carrying capacity of the specimens. Al6061-TiC composites exhibit higher fracture toughness values than their counterparts Al-SiC composites. © 2018 IOS Press and the authors. All rights reserved.
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    Retention of high dielectric constant sodium beta alumina via solution combustion: Role of aluminum ions complexation with fuel
    (Elsevier Ltd, 2018) Gupta, B.; Pujar, P.; Mal, S.S.; Gupta, D.; Mandal, S.
    In the present study, solution combustion technique has been explored to synthesize Sodium ?-alumina (SBA; NaAl11O17) powder and thin films. Three fuels namely urea, glycine and citric acid have been used to seek the feasibility of synthesizing crystalline SBA powder at low temperature. Also, the effect of nature of fuels used as well as calcination treatment on phase evolution and morphology of the as-combusted powder was investigated. Thermal analysis and X-ray diffraction studies suggest the formation of crystalline SBA powder at temperature as low as 259 °C, using urea in the combustion reaction whereas other fuels resulted in amorphous SBA phase and this variation in phase was found due to difference in exothermicity of the fuel used. Thermodynamic and spectroscopic analyses showed that the exothermicity of fuel depends on various factors like (i) standard heat of formation of fuel and (ii) the complexation offered by fuel to metal cations. Furthermore, sodium ?-alumina thin film capacitor (metal-insulator-metal) was also fabricated using urea via spray combustion synthesis. The sodium ?-alumina thin film showed a high dielectric value (?r) of ~21. © 2017 Elsevier Ltd and Techna Group S.r.l.
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    Performance evaluation of mechanical micro-drilling, electrical discharge machining and laser beam machining on nimonic 80A alloy
    (National Institute of Science Communication and Information Resources (NISCAIR) ijact.editor@gmail.com Dr. K. S. Krishnan Marg (Near Pusa Gate) New Delhi 110-012, 2018) Sudhakar, S.; Kumar, P.; Srinivas, G.; Ravishankar, S.; Dupadu, D.; Barshilia, H.C.
    Micromachining techniques such as mechanical micro-drilling, electrical discharge machining (EDM) and laser beam machining (LBM) play an important role in the manufacturing of micro-devices used in mechanical, electronics, aerospace and medical applications. In this paper, an effort has been made to compare the performance of these micromachining techniques with regard to tool wear, burr formation and surface integrity. This is done by producing 20 micro-holes of approximately 800 ?m diameter on a rectangular block (90×30×3 mm3) of Nimonic 80A superalloy. TiAlN coated WC micro-drills, Cu electrodes and CO2 laser beam are used to produce these holes in conventional micro-drilling, EDM and LBM, respectively. The quality of the drilled hole (diameter, surface roughness and micro-burr formation), tool diameter analysis, taper angle and material removal rate (MRR) are compared and reported. A comprehensive analysis is also carried out on overcut, which leads to hole inaccuracy. Results show that mechanical micro-drilling produces better results in the above mentioned characteristics in comparison to LBM and EDM techniques. The relatively better performance of mechanical micro-drilling is attributed to the usage of TiAlN coating on WC tool. © 2018, National Institute of Science Communication and Information Resources (NISCAIR). All rights reserved.
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    Optoelectronic properties of hybrid diodes based on vanadyl- phthalocyanine and zinc oxide nanorods thin films
    (Elsevier B.V., 2019) Raveendra Kiran, M.; Ulla, H.; Satyanarayan, M.N.; Umesh, G.
    Herein, we report the optoelectronic properties of hybrid diodes fabricated using vanadyl phthalocyanine (VOPc) and zinc oxide nanorods (ZNR) with the configuration: ITO/ZNR/VOPc/MoO3/Al. Vertically aligned ZnO nanorods were grown using a simple aqueous solution (AS) method as a function of growth temperature. The correlation between the morphology of ZNR films and the optoelectronic properties of the ZNR/VOPc hybrid devices was investigated. The results show that the hybrid diodes with ZNR films grown at 120 °C offer the best optoelectronic properties. The higher photocurrent responsivity, Rph, (16.28 A/W) was achieved for devices with ZNR films grown at 120 °C. This value is 25 times higher than the Rph value obtained for the devices made with ZnO nanoparticle films that were reported earlier. © 2019
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    Evaluation of Mechanical and Tribological Properties of Directionally Solidified Al-Si Based FG Composite
    (Springer editorial@springerplus.com, 2020) N, R.B.; Mr, R.; Kiran Aithal, K.A.
    The present work aims to fabricate graphite reinforced Aluminum-Silicon (Al-Si) based functionally graded composite (FGC). The FGC’s are obtained with the novel directional solidification technique under the influence of lateral vibrations. The accomplished cast composites are investigated for mechanical and tribological properties to understand the significance of vibrations. To validate the gradation in the structure, the FGC’s have been analyzed for hardness at the top and bottom portion. Results revealed that top portion exhibited high hardness with 66 BHN compared to the bottom portion with 48 BHN respectively. These observations were also supported by the scanning electron microscope (SEM) morphologies which revealed that concentration of Si was more at the top portion. The spatial transition of Si can be attributed to the presence of the chill at the bottom and to the influence of lateral vibrations which has led to variation of properties within the structure. Ultimate tensile strength (UTS) results also showed shift in the properties with the bottom portion exhibiting 143.23 MPa compared to the top portion with 98.3 MPa. Furthermore, wear analysis carried out at the top and the bottom portion of the FGC showed that there is a decrease in wear loss, coefficient of friction and specific wear rate at the top portion compared to the bottom portion. Worn-out surface analysis revealed that graphite addition had imparted the self-lubricating property at the top portion which could serve as anti-friction and anti-wear applications in the automotive sector © 2019, Springer Nature B.V.
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    An investigation on the properties of boron modified Cu–Al–Be polycrystalline shape memory alloys
    (Elsevier Ltd, 2020) Bala Narasimha, G.; Murigendrappa, S.M.
    Effect of microalloying of boron (B) i.e., 0.02–0.15 wt% and the variation of composition of Al and Be from 11.3 to 11.9 wt% and 0.41–0.44 wt% respectively, has been investigated on the grain refinement and shape memory properties of polycrystalline Cu–Al–Be shape memory alloy. The tests have been carried out for microstructure, morphology, phases, crystal structure, phase transformation temperatures and shape recovery ratio. The investigation results in boron has strong impact on grain refinement with minimal addition, followed by Al and Be. AlB2 acts as heterogeneous nucleation site in grain refinement and it increases with increase in B and Al. Transformation temperatures increases with boron up to 0.08 wt% and then decreases, whereas increase in Al and Be decreases the temperatures. Doping and increasing of boron up to 0.15 wt% exhibits complete shape recovery, whereas Be < 0.42 wt% and Al < 11.8 wt% exhibits poor recovery ratio. © 2020 Elsevier B.V.
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    Effect of polarization switching on piezoelectric and dielectric performance of electrospun nanofabrics of poly(vinylidene fluoride)/Ca–Al LDH nanocomposite
    (John Wiley and Sons Inc. P.O.Box 18667 Newark NJ 07191-8667, 2020) Shamitha, C.; Mahendran, A.R.; Anandhan, S.
    At present, highly flexible, durable, and lightweight piezoelectric nanogenerators with high-power density and energy conversion efficiency are of great interest. The present study reports a new synthetic route for Ca–Al layered double hydroxide (LDH) nanosheets and incorporation of these two-dimensional nanosheets as filler material into poly(vinylidene fluoride) (PVDF) to produce composite nanofabrics by electrospinning. The polymorphism, crystallinity, and the interaction between PVDF and LDH were studied by Fourier transform infrared spectroscopy, X-ray diffraction, and differential scanning calorimetry techniques. The synergetic effect of PVDF–LDH interaction and in situ stretching due to electrospinning facilitates the nucleation of electroactive ? phase up to 82.79%, which makes it a suitable material for piezoelectric-based nanogenerators. The piezoelectric performance of PVDF/Ca–Al LDH composite nanofabrics was demonstrated by hand slapping and frequency-dependent mechanical vibration mode, which delivered a maximum open circuit output voltage of 4.1 and 5.72 V, respectively. Moreover, the composite nanofabrics exhibited a high dielectric constant and low dielectric loss due to superior interfacial polarization at low-frequency region with LDH loading, promising its potential applications in electronic devices. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48697. © 2019 Wiley Periodicals, Inc.