Faculty Publications
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Item High temperature tribological studies of cold sprayed nickel based alloy on low carbon steels(Elsevier Ltd, 2019) Padmini, B.V.; Mathapati, M.; Niranjan, H.B.; Sampathkumaran, P.; Seetharamu, S.; Ramesh, M.R.; Mohan, N.The boiler steels of grades SAE213 T11 and T22, find extensive applications in heat exchanger tubes, paper and pulp, chemical industries and refineries. Further, these steels are also used in shafts, cylinders, bearings, and in automotive transmission parts and these aspects are less explored. They experience low wear life in specific components, both at room and slightly higher temperature regimes. In order to protect them from these damages, coatings are deployed involving many techniques like HVOF, Plasma spray, Cold spray etc. so that the life of the components get extended. In cold spray coatings, the powders are fed at very high impact velocities of up to 1200 m/s on the substrate and undergo plastic deformation during the impact. There is no oxidation of the powder takes place during the process, as the coating is done at very less temperature and this is one of the lead characteristic of cold spray technique. This particular work mainly focuses on evaluating the tribological behaviour of nickel based super alloy powder on T11 and T22 low alloy steels by cold spray method, using pin on disc machine both at room temperature as well as at 200, 300 and 400 °C. The associated tests such as hardness, porosity, and microstructure have been undertaken to support the wear data. The wear damage assessment has been carried out using scanning electron microscope to arrive at the mechanism and also to give credence to the wear data. © 2019 Elsevier Ltd.Item Multiple response optimisation of process parameters during drilling of GFRP composite with a solid carbide twist drill(Elsevier Ltd, 2020) Bhat, R.; Mohan, N.; Sharma, S.; Dayananda Pai, D.; Kulkarni, S.M.The article focuses on investigating the effect of operational parameters like feed and speed along with the composite material thickness on the damages caused in the glass fibre reinforced polymer (GFRP) composites during the drilling process. The GFRP composite studied in the presented work comprises E-glass fibre as the reinforcing material and the marine-grade isophthalic polyester as the binding matrix. Multiple responses considered in work comprises Peel-up delamination, push-down delamination and surface roughness. The technique for order of preference by similarity to ideal solution (TOPSIS) is used to develop the performance index and optimise the multiple response problem. Stepwise analysis of variance (S-ANOVA) is used to investigate the significance of each input parameter. The interaction effects of the variables are investigated using the response surface plots. The results indicate that the composite thickness contributes maximum towards the variance in the overall performance index (21.30%) and the optimum combination obtained using TOPSIS approach within the experimental limits for the selected GFRP is N3f1t1 with the maximum value of Pi (0.888). The regression model developed proves to have high goodness of fit with just 6.01% average error between predicted and experimental values. © 2019 Elsevier Ltd.Item Predictive analysis of peel up delamination in glass fibre reinforced polyester composite drilling(Transstellar Journal Publications and Research Consultancy Private Limited (TJPRC) editor@tjprc.org, 2019) Bhat, R.; Mohan, N.; Kulkarni, S.M.; Sharma, S.Composites are the engineering materials, comprising two constituents: reinforcing and the matrix or binder material. the composite machining, particularly, drilling is a complex process in comparison to the machining of traditionally employed engineering structural materials. Delamination is the most prevalent integrity issue in composite drilling. In the present work, the independent variables are categorized as continuous and categorical variables. Speed and feed are chosen as the continuous variables, whereas, the drill tool diameter and material thickness are considered as categorical variables. The peel up delamination is chosen as the response. The central composite design form of RSM is employed to develop the experimental design and develop the response regression model. The developed model is then validated using an additional set of small number of experiments and the degree of affirmation is determined. The standard error obtained analytically is 5.91%. The experimental mean standard error for the randomly conducted validating experiment obtained is 4.23%. The validation shows a high degree of agreement (99.75%) between the theoretical and analytical values. © TJPRC Pvt. Ltd.Item Calorespirometric investigation of Streptococcus zooepidemicus metabolism: Thermodynamics of anabolic payload contribution by growth and hyaluronic acid synthesis(Elsevier B.V., 2019) Mohan, N.; Allampalli, S.S.; Achar, A.; Swaminathan, N.; Sivaprakasam, S.Thermodynamic analysis of carbon flux competing for pathways of S. zooepidemicus in the production of catabolic (Lactic acid) and anabolic (Biomass and Hyaluronic Acid) products is investigated to assimilate the thermodynamic advantages of biopolymer production. Calorespirometry was employed to fingerprint the on-going HA production process and to predict reliable estimation of catabolic and anabolic product yields. This study accomplished the HA production at different initial glucose concentrations, S0 (10–60 g/L) to subject different levels of anabolic burden on S. zooepidemicus. Anabolic payload comprising Biomass and HA yields showed a concomitant decrease with respect to the increased concentration of S0. Chemical entropy exported over the cell surface in the form of LA production exhibited an increasing trend at different levels of glucose, thus reducing the total yields of biomass and HA. Thermodynamically anabolic load contributed by biomass and HA production found to have minor influence over the driving force of S. zooepidemicus metabolism due to their lower yields. The entropy contribution to the overall driving force is significant (T?SX= [Formula presented] ?rGX) at the higher biomass yields. This study allows the prediction of optimum biomass yield towards enhanced HA production and addresses the scope of ‘thermodynamic constraints’ application in real-time process monitoring and control using data reconciliation strategy in the near future. © 2019 Elsevier B.V.