Faculty Publications
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Item Structure and rheology of chitosan-nanohydroxyapatite composite hydrogel for soft tissue regeneration(American Institute of Physics Inc. subs@aip.org, 2020) Kumar, B.Y.S.; Isloor, A.M.; Periasamy, K.; Kumar, G.C.M.Chitosan (CS) hydrogels show desirable characteristics to use a soft tissue implants due to its biocompatibility, biodegradability and antimicrobial characteristics. However, the structural stability hinders its application in vivo. In the present work nanohydroxyapatite (HAp) was reinforced with chitosan hydrogel and to develop chitosan-hydroxyapatite (CS-HAp) composite hydrogel. The nanohydroxyapatite modifies the hydrogel network by promoting the secondary hydrogen bonds thereby enhances the mechanical stiffness. The elastic modulus could reach 10 kPa which is necessary for the proposed application. Overall, chitosan-hydroxyapatite composite hydrogels are the promising implant materials for next-generation soft tissue regeneration. © 2020 Author(s).Item Model updating of material damping in composite material of rotor-bearing support system(American Institute of Physics Inc. subs@aip.org, 2020) Gonsalves, T.H.; Kumar, G.C.M.; Ramesh, M.R.In this paper the finite element model updating technique is evaluated for the estimation and modeling of material damping of composite material intended to be used in a high-speed rotor-bearing support system. An accurate estimation and modeling of material damping is required for the proper understanding of the dynamic behavior of composite material used in the high-speed rotor-bearing system. Due to the contrasting relevance of material damping as rotating internal damping and stationary external support damping in a high-speed rotor-bearing system, updating methodology is required to be varied. Hence to start with, the finite element numerical model updating of stationary damping of composite material is presented here using the test data extracted from the experimental free vibration and dynamic mechanical analysis (DMA) tests. © 2020 Author(s).Item Synthesis and characterization of graphene oxide by modified hummer method(American Institute of Physics Inc. subs@aip.org, 2020) Kumar, G.C.M.; Jalageri, M.Graphene oxide was prepared by oxidizing the graphite powder using the modified hummer method. Characterization studies are done to investigate physical and chemical properties. In this study, Scanning electron microscopy(SEM), Energy dispersive x-ray spectroscopy(EDX), Fourier transform infrared spectroscopy (FTIR), and X-Ray Diffraction(XRD) results are used.FTIR shows that graphite oxidized and formed oxygen atoms in the graphite layer and forms C=O,C-H,COOH Chemical bonding with graphene. The XRD results showed 2 of 11.300 with interlayer spacing of 0.771nmSEM images report ultra-thin layers. It is a promising method to synthesize GO for various applications like biomedical, electrical, and others. © 2020 Author(s).Item Material optimization of spur gear tooth(American Institute of Physics Inc. subs@aip.org, 2020) Kumar, G.C.M.; Basheer, B.; Sutar, S.; Doddamani, M.Gear is the most critical component widely used in the transmission of motion and power between shafts. During motion, the gears are loaded, which develops critical bending stress at the root of the gear and also at the point of contact. The loading point "Highest Point Single Tooth Contact" (HPSTC) is the most critical in any gear. The present research work involves a reduction in the weight of gear by optimizing material inside the tooth. This work involves removing material by making holes inside the tooth at different locations with different sizes. The FEM analysis leads to optimizing the material utilization and is carried out using ANSYS APDL tool. © 2020 Author(s).Item Gear stress reduction using stress relief features: A review(Elsevier Ltd, 2021) Sutar, S.S.; Kumar, G.C.M.; Doddamani, M.To increase the life of the gear against fatigue failure, which occurs because of repetitive tensile stresses at the root of the tooth is a challenging task. The inability of gear is very sudden against fatigue loading without giving any indications of failure. Many researchers gave practical ways for improving the gear design like, the use of advanced material, harden the gear surface by heat treatment and carburization, improve the surface finish by shot penning method, changing the pressure angle, use asymmetric gear tooth, modify the shape of root fillet curve, etc. But focusing at interchangeability of gear systems all these ways are insufficient. To overcome this and to achieve a reduction of stresses in the stressed zone under loading, introducing stress relief feature in those areas is a powerful technique. For stress reduction in spur gear, this research work reviews use of stress-relieving features like circular shaped, elliptical-shaped, aero fin-shaped in the stressed zone. Also, it has summarized the effect of combinations of stress relief features, optimized locations of these features to minimize the stresses and increase the life of the gear. © 2021 Elsevier Ltd. All rights reserved.Item Short term creep behavior of neem wood veneer epoxy composites(American Institute of Physics Inc., 2023) Nagamadhu, M.; Kivade, S.B.; Vijay Kumar, S.V.; Kumar, G.C.M.Neem wood used many structural applications due to its coarse grain with interlocking fibers leads to excellent mechanical properties with a very good life. However, wood structures are exposed to various environmental conditions, so it is necessary to investigate the effect of time and temperature for different stacking sequences. This paper aims to explore the importance of time and temperature of neem wood veneer epoxy composites at various stacking sequence and interfacial bonding. The Dynamic Mechanical Analyzer used to study short term creep at a nitrogen environment using a three-point bending condition. The result shows neat neem wood veneer exhibit a higher percentage of strain as compared to neem wood epoxy composites. On the other hand, the stacking sequence having significant changes in dynamic mechanical and creep studies, storage modulus (G') & loss modulus (G'') increases along the wood fiber direction with minor load-bearing capacity in lateral direction. By varying the orientation of the wood veneer mechanical and thermo-mechanical properties improved in both longitudinal and lateral direction. © 2023 Author(s).Item Finite Element Analysis of a Natural Fiber (Maize) Composite Beam(Hindawi Limited 410 Park Avenue, 15th Floor, 287 pmb New York NY 10022, 2013) Saravana Bavan, B.D.; Kumar, G.C.M.Natural fiber composites are termed as biocomposites or green composites. These fibers are green, biodegradable, and recyclable and have good properties such as low density and low cost when compared to synthetic fibers. The present work is investigated on the finite element analysis of the natural fiber (maize) composite beam, processed by means of hand lay-up method. Composite beam material is composed of stalk-based fiber of maize and unsaturated polyester resin polymer as matrix with methyl ethyl ketone peroxide (MEKP) as a catalyst and Cobalt Octoate as a promoter. The material was modeled and resembled as a structural beam using suitable assumption and analyzed by means of finite element method using ANSYS software for determining the deflection and stress properties. Morphological analysis and X-ray diffraction (XRD) analysis for the fiber were examined by means of scanning electron microscope (SEM) and X-ray diffractometer. From the results, it has been found that the finite element values are acceptable with proper assumptions, and the prepared natural fiber composite beam material can be used for structural engineering applications. © 2013 D. Saravana Bavan and G. C. Mohan Kumar.Item Simple viscosity criterion for injection moulding thermoplastics(Society of Plastics and Rubber Engineers, 2015) Lakkanna, M.; Kumar, G.C.M.; Kadoli, R.Thermoplastics are available in abundance with immense properties variations, but only few are processed by injection moulding. So this manuscript deals with this issue by proposing a design criteria contingent to a particular combination of material properties, machine specifications and moulding features. Pertinently embracing their behavioural relationships a unique analytical design criterion was deduced directly from first principles. Comprehending injection conduit to an analogous capillary tube; as well as cognising generalized Newtonian concept for thermoplastic melts with power-law description of in-situ rheological behaviour. The proposed criterion being simple and generic easily adapts in early mould design itself and comprehends entire range of thermoplastic in-situates. Hereafter any thermoplastics could be injection moulded by contingently designing an exclusive mould feed system for it. This percipience was elucidated by continuously sensitising a hypothetical intervene across all thermoplastics while explicitly appraising, why melt kinesis lacunae can never be fully rectified, despite manipulating process parameters many times? Finally, the manuscript extends hereto-believed linear relationship between runner-conduit size and in-situ melt state to direct exponential proportionality with discrete slope and altitude for each thermoplastic behaviour..Item Criticality of appreciating non-newtonianivity in plastic injection mould conduit design(Begell House Inc., 2015) Lakkanna, M.; Kadoli, R.; Kumar, G.C.M.The prime intention of this research was to emphasise criticality of Non-Newtonian injectant behaviour to design ideal runner conduits for plastic injection moulds. Power-law constitutive relation was representatively adopted so shear thinning index could contrast, both Non-Newtonian and Newtonian behaviours together. An a priori analytical solution was developed from Power-law constitutive relation analogous to celebrated Hagen-Poiseuille solution for tubular runner conduits. This solution leveraged the computational intelligence advantage to enable a design criteria for perfect injection into impression gap synchronising injector capacity, injectant character as well as desired moulding features. The proposed design criteria readily adapts in practise including extremely complicated feed system configurations. Further to incorporate comprehensiveness, continuous sensitivity method was also adopted to discriminate cruciality over an infinite dimension scale, which lead insight into various important aspects that would certainly form a basis to diagnose filling issues reasoning several defects. For representation a sample set of runners from realistic, productive moulds that were initially designed with Newtonian hypothesis and later during trails heuristically optimised were compared, interestingly, they were statistically skewed towards runner sizes that were directly determined appreciating Non-Newtonian injection behaviour. Therefore, it was concluded that Non-Newtonian injection behaviour should have significant prominence in injection mould design criteria. © 2015 Begell House, Inc.Item Influence of Ni-P Coated SiC and Laser Scan Speed on the Microstructure and Mechanical Properties of IN625 Metal Matrix Composites(Springer US, 2015) Sateesh, N.H.; Kumar, G.C.M.; Krishna, K.Nickel based Inconel-625 (IN625) metal matrix composites (MMCs) were prepared using pre-heated nickel phosphide (Ni-P) coated silicon carbide (SiC) reinforcement particles by Direct Metal Laser Sintering (DMLS) additive manufacturing process under inert nitrogen atmosphere to obtain interface influences on MMCs. The distribution of SiC particles and microstructures were characterized using optical and scanning electron micrographs, and the mechanical behaviours were thoroughly examined. The results clearly reveal that the interface integrity between the SiC particles and the IN625 matrix, the mixed powders flowability, the SiC ceramic particles and laser beam interaction, and the hardness, and tensile characteristics of the DMLS processed MMCs were improved effectively by the use of Ni-P coated SiC particles. © 2015, Springer New York.