Faculty Publications

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Author: search.filters.author.Vishwanatha, H.M.

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    Effect of Mn on cooling behaviour and microstructure of chill cast Zn-Al (ZA8) alloy
    (2012) Ramesh, G.; Vishwanatha, H.M.; Prabhu, K.N.
    In the present work, the effect of manganese addition to ZA8 alloy on thermal analysis parameters, heat transfer and microstructure was investigated. The thermal analysis parameters were found to be significantly affected by chemical modification of ZA8 alloy. Cooling curve and differential scanning calorimetry analyses of modified alloy showed nucleation of new phase other than b dendrites. Chilling of modified alloy resulted in decreased liquidus temperature and enhanced eutectoid transformation. Further, chilling avoids the formation of intermetallic compounds in modified alloy. The heat flux transients were estimated using inverse modelling during solidification of unmodified and modified alloys against different chills. The peak heat flux decreased on addition of Mn to ZA8 alloy. Differential scanning calorimetry analysis indicated that the addition of Mn to ZA8 alloy decreases the heat of solidification. The addition of Mn to ZA8 alloy increased the contact angle, indicating decreased wettability of the modified alloy on the chill surface. The microstructure of ZA8 with Mn showed an increased amount of b phase and a decreased amount of eutectic. X-ray diffraction analysis confirmed the formation of MnAl6 intermetallics in Mn added ZA8 alloy. Chilling with chemical modification resulted in enhanced decomposition of b phase. © 2012 Institute of Materials, Minerals and Mining.
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    Modelling and Comparative Analysis of Epoxy-Fly-Ash Composite with Alloys for Bracket Application
    (MDPI, 2022) Raghunandan, A.B.; Chiniwar, D.S.; Hiremath, S.; Sondar, P.; Vishwanatha, H.M.
    The current study compares and analyses the fly-ash–epoxy composite structure with alloys for bracket applications. A dispersed reinforcement composite is created by combining epoxy and fly-ash. Three different prototypical brackets are modelled and analysed using the finite element method, and their results are compared to common alloys used in the manufacture of L-shaped brackets. The mechanical properties of the composite material are calculated using a rule of mixtures, and the properties of the composite material are modified by changing the percentage composition of fly-ash. Based on equivalent stress and total deformation, all geometrical models are analysed and compared. The analysis results appear to be appropriate for broadening the scope of the application of epoxy-based composites for small-scale and large-scale applications. The results also show that the composite material can be used to make a variety of structural elements with high design complexity, such as bulkheads and other structural components. © 2022 by the authors.
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    Modelling of single and multi-port manifolds and studying the influence of structural and thermal behaviour on exhaust manifolds used in automotive applications
    (Springer-Verlag Italia s.r.l., 2024) Sangamesh, R.; Twinkle, R.; Chiniwar, D.S.; Vishwanatha, H.M.; Sondar, P.; Hiremath, S.
    With the new pollution control rules and surging requirements for the increase in efficiency of the internal combustion engines, designing the exhaust manifold has become a growing area of interest. The present work focuses on modelling the multi-end exhaust manifold and comparing it with the single-end exhaust manifold. Both the structural and thermal analyses are carried out using the finite element method. Along with the modified design, various materials such as mild steel, cast iron, stainless steel and medium carbon steel are also evaluated for their structural and thermal behaviour. It is found that the multi-end exhaust manifold performs better in terms of better stress and temperature distribution in comparison to the single-end exhaust manifold. The magnitude of the stress experienced by multi-end exhaust manifolds is 20 MPa lesser than single-end exhaust manifolds. However, the change in material has a marginal effect in terms of stress and temperature distribution. © The Author(s) 2022.
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    The influence of hygrothermal aging on the hoop tensile strength of glass fiber wound polymer composites fabricated via filament winding technique
    (Institute of Physics, 2024) Biradar, S.; Hiremath, S.; Vishwanatha, H.M.; Joladarashi, S.; Kulkarni, S.M.
    The study investigates the impact of moisture environment treatment, on the hoop tensile strength (HTS) of glass fiber-reinforced polymer (GFRP) composites, through hygrothermal aging. GFRP cylinders were fabricated with varied parameters—volume fraction, winding angle, and stacking sequences using a filament winding machine. The fabricated samples are subjected to hygrothermal aging using seawater and tap water with oil at 80 °C for 1080 h (45 days). The HTS tests were performed on unaged and aged samples. There was a reduction in HTS for aged samples which is attributed to heat, seawater contamination, and oil. The highest and lowest HTS values recorded are 402.9 MPa and 118.3 MPa for unaged and tap water with oil-aged samples respectively. HTS in aged samples is compared with unaged samples. The study opens up avenues in identifying the best-suitable combination for retaining HTS under various aging conditions. © 2024 The Author(s). Published by IOP Publishing Ltd.
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    Effect of addition of Ce and accumulative roll bonding on structure-property of the Mg-Ce-Al hybrid composite and its prediction and comparison using artificial neural network (ANN) approach
    (Institute of Physics, 2024) Anne, G.; Bhat, N.; Vishwanatha, H.M.; Ramesh, S.; Maruthi Prashanth, B.H.; Sharma, P.; Aditya Kudva, S.; Jagadeesh, C.; Nanjappa, Y.
    Light alloys play a crucial role in realizing the national strategy for energy conservation and emission reduction, as well as promoting the upgrading of manufacturing industries. Mg/Al composite laminates combine the corrosion resistance and ductility of aluminium alloy with the lightweight characteristics of magnesium alloy. The addition of Ce (rare earth elements) can improve the mechanical properties of magnesium via grain refinement and improve the ductility of the hybrid composites. In the present work, an investigation on addition of Ce into the Mg/Al matrix through Accumulative Roll Bonding (ARB) has been presented. The Mg/Ce/Al hybrid composite consists of Mg-4%Zn alloy and Al 1100 alloy with 0.2% Ce particles added between the dissimilar layers. The changes occurred in the evaluation of microstructure, corrosion and mechanical properties of the Mg/Ce/Al hybrid composite as a result of deformation process and also the addition of Ce have been explicated. The ARB parameters: temperature, rolling speed, percentage reduction, and aging time, have been studied. An increase of about 2.36 times in strength and hardness of the hybrid composite, has been reported. Further, the structure-property relations in the Mg/Ce/Al hybrid composites were aslo predict and compare using machine learning models: Decision Tree and Multi-Layer Perceptron (MLP) models. © 2024 The Author(s). Published by IOP Publishing Ltd.
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    Effect of alkaline treatment on mechanical properties of natural fiber-reinforced composite
    (Korean Society of Mechanical Engineers, 2024) Sangamesh, R.; Hiremath, S.; Biradar, S.; Kumar B, S.; Sondar, P.; Vishwanatha, H.M.
    Natural fiber-reinforced composites are gaining popularity as eco-friendly alternatives to conventional plastics across various industries. This study investigated the fabrication of composites using areca leaves as the reinforcing filler material within an epoxy matrix. The composites were prepared using the hand-layup technique, with different weight fractions of fibers. Before composite fabrication, the areca leaves were treated with NaOH solution. A comprehensive set of tests, including tensile, compression, flexural, impact, and erosion tests, was conducted on these composites to evaluate their mechanical properties. The results showed that untreated composites exhibited superior performance in tensile (39 MPa) and compression tests (59 MPa with 45 % fiber content), while NaOH-treated composites performed better in flexural (64–67 MPa) and impact tests (21 kJ/m2 at higher fiber content). Erosion testing revealed that composites with lower filler concentrations demonstrated improved wear resistance compared to those with higher filler content, with erosion rates significantly influenced by sand concentration and particle size. These findings were supported by fracture surface analysis using scanning electron microscopy (SEM). This study provides valuable insights into the potential of areca leaf-reinforced composites as sustainable materials for various applications. © The Korean Society of Mechanical Engineers and Springer-Verlag GmbH Germany, part of Springer Nature 2024.