Faculty Publications
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Item Synthesis and Characterization of PVDF/Graphene Nanocomposite Membrane for Water Treatment Applications(Trans Tech Publications Ltd, 2022) Rao, S.; Avinash, A.; As, S.; Hegde, C.; Isloor, A.M.; Vinayak, V.R.Membrane technology advancement has gained momentous consideration around the globe because of their appealing highlights, such as effectiveness, low expenses, and effective solutions for longstanding issues in alchemical industries. This study expected to incorporate graphene nanoparticles into Polyvinylidene difluoride (PVDF) to form nanofiltration (NF) layers using DMF (Dimethyl formamide) as solvent via DIPS (diffusion induced phase separation) technique. PVDF polymer membrane performances with varied percent (1 – 6% wt.) of graphene concentrations are studied with Infrared spectral, water uptake, water contact angle, and ion rejection measurements. Scanning electron microscope (SEM) analysis showed that the pore size is often regulated by incorporating graphene nanoparticles (80-90 nm) as compared to PVDF membranes. The PVDF membranes exhibited a relative increase in the contact angle from PVDF to PVDF-G6%, i.e., 50.3° to 63.46 ± .3, thus, showing a relative increase in hydrophobicity. The higher percent of graphene (> 6% by wt.) results in nano-particle accumulation that showed the performances of PVDF/graphene rejection possessing relatively the same results. The results confirmed that the prepared membranes possess an excellent ability to treat wastewater. © 2022 Trans Tech Publications Ltd, Switzerland.Item Microstructure, mechanical and wear properties of the A357 composites reinforced with dual sized SiC particles(Elsevier Ltd, 2019) Avinash, A.; Bontha, S.; Krishna, M.; Koppad, P.G.; Ramprabhu, T.Current work reports on the development of A357 alloy composite which is reinforced with dual size SiC particles by stir casting route. Influence of different weight fractions (3% coarse+ 3% fine, 4% coarse + 2% fine, and 2% coarse + 4% fine) of dual size SiC particles on mechanical properties and wear resistance of A357 composites is the focus of this work. Hardness and tensile properties were studied for dual size composites and then were compared with A357 alloy. Microstructural study, fractured surface and worn surface investigation were carried out using optical and scanning electron microscopes respectively. Microstructural analysis showed fairly uniform dispersion of dual size SiC particles in A357 matrix with good interfacial bonding. Compared to A357 alloy, the composites showed improvement in hardness, yield, and tensile strength. In particular, composite with 4 wt. % of fine and 2 wt. % of large SiC particles displayed the highest tensile strength while composite with 4 wt. % of large and 2 wt. % of fine SiC particles exhibited high hardness and wear resistance among A357 alloy and dual particle size composites. The strengthening mechanisms that contributed to improvement in strength values were effective load transfer and dislocation strengthening due to thermal mismatch. © 2019 Elsevier B.V.Item The effect of heat treatment on the mechanical and tribological properties of dual size SiC reinforced A357 matrix composites(Elsevier Editora Ltda, 2020) Avinash, A.; Prabhu, T.R.; Babu, U.S.; Koppad, P.G.; Gupta, M.; Krishna, M.; Bontha, S.In the present work, the effect of aging temperature and particle size ratio of SiC particles on the mechanical and tribological properties of A357 composites reinforced with dual particle size SiC were investigated. The composites were prepared by melt-stirring assisted permanent mold casting technique with different weight fractions (3% coarse +3% fine, 4% coarse +2% fine, and 2% coarse +4% fine) of large and small size SiC particles. These three prepared composites are referred as DPS1, DPS2 and DPS3 composites. The solutionizing temperature was maintained constant at 540 ?C for 9 h while the aging was done at 160 ?C, 180 ?C and 200 ?C (T6 treatment) for 6 h. Optical and scanning electron microscopy studies showed fairly uniform dispersion of dual size SiC particles in A357 matrix with good interfacial bonding. High-resolution transmission electron microscopy images showed formation of uniformly dispersed needle-like phase and spherical shaped -Mg2Si precipitates under peak aging conditions. Compared to T6 treated A357 alloy, the T6 treated DPS A357 composites showed improved yield strength, tensile strength, hardness and wear resistance. Among the three composites, hardness and wear resistance of T6 treated DPS2 composite was found to be significantly higher when compared to the other two composites (DPS1 and DPS3). Ratio of large particles to small particles also seems to effect the mechanical and tribological properties. Presence of more small particles was found to be good for strength and ductility whereas more large particles were found to be good for hardness and wear resistance. © 2020 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND licenseItem Free vibration analysis of A357 alloy reinforced with dual particle size silicon carbide metal matrix composite plates using finite element method(Polska Akademia Nauk, 2021) Avinash, A.; Mahesh, V.; Prabhu, R.T.; Gowdru Chandrashekarappa, M.G.C.; Bontha, S.In this work, the free vibration behaviour of A357 composite plate reinforced with dual particle size (DPS) (3 wt.% coarse + 3 wt.% fine, 4 wt.% coarse + 2 wt.% fine, and 2 wt.% coarse + 4 wt.% fine) SiC is evaluated using the finite element method. To this end, first-order shear deformation theory (FSDT) has been used. The equations of motion have been derived using Hamilton's principle and the solution has been obtained through condensation technique. A thorough parametric study was conducted to understand the effect of reinforcement size and weight fraction, boundary conditions, aspect ratio and length-to-width ratio of plate geometry on natural frequencies of A357/DPS-SiC composite plates. Results reveal significant influence of all the above variables on natural frequency of the composite plates. In all the cases, A357 composite plate reinforced with 4 wt.% coarse and 2 wt.% fine SiC particles displayed the highest natural frequency owing to its higher elastic and rigidity modulus. Further, the natural frequencies increase with decrease in aspect ratio of the plate geometry. Natural frequency also decreases with increase in the number of free edges. Lastly, increasing the length-to-width ratio drastically improves the natural frequency of the plates. © 2021 Polish Academy of Sciences. All rights reserved.Item Al/Graphene/CNT Hybrid Composites: Hardness and Sliding Wear Studies(Belgrade University, 2021) Manjunath Naik, H.R.; Manjunatha, L.H.; Koti, V.; Avinash, A.; Koppad, P.G.; P, S.K.Graphene and carbon nanotubes are two carbon based materials known for their unique wear and friction properties. It would be quite interesting to understand the wear behavior of aluminium hybrid composites when these two nanosize reinforcements are incorporated into it. The hybrid composites with varying weight fractions of graphene (1, 2, 3 and 5 wt.%) and fixed CNT content of 2 wt.% were produced using powder metallurgy technique. The effect of varying graphene content on hardness and sliding wear of hybrid composites was studied. The wear tests were done as per ASTM G-99 standard with fixed sliding velocity (2 m/s) and sliding distance (1200 m) but varying applied load (10 - 30 N). Worn surface analysis was conducted using scanning electron microscope to arrive at wear mechanisms responsible for wear of aluminium and its hybrid composites. Increase in graphene content led to increase in bulk hardness with highest value of 61 RHN for hybrid composite with 3 wt.% graphene content. The wear rate of hybrid composites was found to be decreasing with enhancement in graphene content. Lower wear rate in hybrid composites was due to the formation of lubricating layer on the worn surface. © Faculty of Mechanical Engineering, Belgrade. All rights reservedItem Prediction of transient temperature at bit-rock interface using numerical modelling approach and optimization(Springer-Verlag Italia s.r.l., 2024) Vijay Kumar, V.K.; Avinash, A.; Pon Selvan, C.P.; Girish, B.M.; Kunar, B.M.; Flores Cuautle, J.; Ramakrishna, V.K.; Vinayak, V.One of the major factors impacting on drill bit performance during rock drilling is interface temperature. The performance of the drill bit during drilling operations not only depends on operations parameters but also the properties of rock during drilling in laboratory and field investigations. Hence the present study focused on interface of bit-rock, the temperature had been determined by developing a specially grounded thermocouple. Over 500 different test conditions were performed in each rock sample's case during experimental drilling on a cylindrical block of UCS of 17.83 MPa (fine-grained sandstone grey-FG), 13.70 MPa (medium-grained sandstone-MG), and 51.67 MPa (fine-grained sandstone pink-FGP). The results revealed that the average increase in interface temperature for MG is about 53.74%, FG is about 93.26%, and FGP is about 165.22%. The significant parameters such as uniaxial compressive strength (26%), depth (33%), rate of penetration (15.2%), diameter of the bit (5.26%), and thrust (5.04%) are the most influenced parameters on temperature, followed by spindle speed (1.04%), and torque (0.23%) respectively. The proposed regression models successfully predict the temperature with an R2 value of 91.74%, 90.30%, and 90.95% for MG, FG, and FGP, respectively. Finally overall regression model is developed by considered operational parameters with rock properties to predict temperature and R2 value of 80.8% for all three types of rock samples considered. © The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature 2023.