Browsing by Author "Herbert, Mervin A."

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Automatic Path Planning System for Mobile Vehicle with Robot using Ultra-Wide Band and Method thereof
(Indian Patent Office, Chennai, 2024-12-13) Shettigar, Arun Kumar; P, Navin Karanth; Kumar, Gajula Raj; Rao, Shrikantha S; Herbert, Mervin A.; National Institute of Technology Karnataka, Surathkal
Development of Demand Forecast and Inventory Management Decision Support System Using AI Techniques
(National Institute of Technology Karnataka, Surathkal, 2018) Kumar, Prasanna; Herbert, Mervin A.
Influence of Heat-Treatment on Structure and Properties of Nickel Titanium Alloy
(National Institute of Technology Karnataka, Surathkal, 2021) Mukunda, Sriram.; S, Narendranath.; Herbert, Mervin A.
In this present investigation, the low temperature annealing heat-treatment was carried out at four different temperatures between 300oC and 450oC. The observation of the microstructure has been carried out using transmission electron microscopy as per ASTM F86. An EDAX analysis has been carried out as per ASTM F1375 - 92(2012) to ascertain the chemical composition. An x-ray diffraction has been carried out as per ASTM F2024 - 10(2016) to ascertain the phases present in the alloy. The DSC has been carried out as per ASTM D3418 on the alloy to analyze the transformation temperatures to confirm the superelastic nature of the material. The material has been subjected to mechanical testing by performing the tensile test as per ASTM E8 and Vickers hardness test as per ASTM E92 – 17. The tribological characteristics of the material has been analyzed as per ASTM G-132a by conducting abrasive wear test at room temperature. The superelasticity test has been performed as per ASTM F2516-18 at room temperature by varying the magnitude of strain. An electrochemical corrosion test has been conducted as per ASTM F-2129 on NiTi alloy with a prepared solution to study the corrosion resistance of the same. The salient results of the systematic investigation carried out within the scope of the investigation indicate that the chemical composition of the constituents present in the alloy assessed by EDAX analysis indicate that the Ni-Ti alloy used in this investigation is a 50:50 Ti-Ni alloy which is well within the tolerance limit for 50:50 TiNi alloy as per ASTM F1375 - 92(2012). The alloy is seen to be slightly on the Titanium-rich side. The TEM of the as-received NiTi alloy indicates the presence of martensite which appears as a needle-like region and also a shaded region indicating presence of dislocation network. Whereas the 50% Nickel - 50% Titanium alloy subjected to optimum low temperature annealing heat-treatment at 350oC for one-hour duration indicates the presence of martensite, dislocation network and formation of NiTi alloy grains. The extent of dislocation network has relatively reduced and the grain size of NiTi alloy has relatively increased. vi The XRD of as-received NiTi alloy indicates that the presence of martensitic and austenitic phase. Whereas, the X-ray diffractogram of the 50% Nickel – 50% Titanium alloy subjected to optimum low temperature heat-treatment at 350oC for one-hour duration indicates that the presence of martensitic phase, austenitic phase and an additional Rhombohedral phase. The DSC thermogram of the as-received NiTi alloy indicates that there are no significant peaks seen in the heating as well as the cooling curves meaning that there are no distinct phase transformations of either Austenite-Martensite or Martensite- Austenite present in the material. Whereas, the DSC thermogram of 50% Nickel - 50% Titanium alloy subjected to optimum low temperature heat-treatment at 350oC for onehour duration indicates that the material shows a single-stage transformation from austenite-martensite phase in the cooling cycle and a two-stage transformation from martensite-rhombohedral phase and rhombohedral-austenite phase in the heating cycle. The tensile test carried out for the as-received material in this investigation indicates that the material is super-elastic by nature. The comparison of the ultimate tensile strength of as-received 50% Nickel - 50% Titanium alloy and the alloy sample subjected to an optimum low temperature annealing heat-treatment of 350oC for a duration of 1 hour indicates that there is an improvement in ultimate tensile strength of 350oC heat-treated sample by 44.40% as compared to that of as-received 50% Nickel - 50% Titanium alloy. The Vickers Pyramid Number of as-received material is 421 VPN. The comparison of hardness of 50% Nickel - 50% Titanium alloy subjected to optimum low temperature annealing heat-treatment at 350oC for one-hour duration with the hardness of as-received material indicates that the hardness has increased by 14.5% as compared to hardness of as-received 50% Nickel - 50% Titanium alloy. The abrasive wear test indicates that when the load is increased, the wear mass loss rate is relatively at a higher rate upto 15N and with further increase in the load, the mass loss rate is relatively at a slower rate. The comparison of the abrasive wear between the as-received 50% Nickel - 50% Titanium alloy and 50% Nickel - 50% Titanium alloy subjected to optimum low temperature annealing treatment at 350oC for one-hour duration indicates that the mass loss of low temperature annealed 50% Nickel - 50% Titanium alloy is lesser by 37.17% to 47.58% than the mass loss of as -received 50% vii Nickel - 50% Titanium alloy. This trend of reduction in the mass loss or in other words the improvement in wear resistance has been found true at all the axial loads investigated within the scope of this investigation. The variation of strain for different levels of stress during loading and after release of load at different pre-determined strain values indicate that the material even after loading upto stress level of 700 MPa does not break but returns back to the original stress value after release of the load indicating that the unloading curve had followed a hysteresis path compared to loading curve by returning back to the same point which means that the material is exhibiting superelastic behavior. The extent of improvement in Superelasticity of 50% Nickel - 50% Titanium alloy subjected to optimum low temperature annealing heat-treatment of 450oC for one-hour duration is in the range of 54.5% to 95.2 % as compared to superelasticity of as-received material. The electrochemical corrosion study carried out for as-received NiTi alloy indicates that the electrochemical corrosion rate for the material was found to be 0.0613 mm/year. The corrosion rate of 50% Nickel - 50% Titanium alloy subjected to low temperature annealing heat-treatment at different temperatures is less than the corrosion rate of asreceived 50% Nickel - 50% Titanium alloy. The extent of improvement in the corrosion resistance of 50% Nickel - 50% Titanium alloy subjected to optimum low temperature annealing heat-treatment at 350oC for one-hour duration is 35.72% as compared to corrosion resistance of as-received 50% Nickel - 50% Titanium alloy.
Performance and Emission Characteristics of Vateria Indica Oil as Alternative Fuel for Petrodiesel in CI Engine
(National Institute of Technology Karnataka, Surathkal, 2019) Rao, Gangadhara.; Kumar, G. N.; Herbert, Mervin A.
Vateria Indica Linn seeds contain nearly 19% oil/fat which can be converted into biodiesel by normal method of esterification followed by transesterification generally adopted for high FFA oils. Biodiesel is a promising alternative fuel for CI engines. In the present work, study of the combustion, performance and emission characteristics of a CI engine fuelled with Vateria Indica biodiesel blends at 180 bar, 200 bar and 220 bar injection pressures (IP) and injection timings at 19obTDC, 23obTDC and 27obTDC (before TDC) is carried out. Blending is done in volumetric ratios of 10%, 15%, 20%, 25% of biodiesel with diesel which are called as B10, B15, B20, B25. Increasing fuel injection pressure promotes atomization, and full penetration into the combustion chamber leading to better combustion. Blend B25 showed better thermal efficiency of the order of 33.03% and minimum NOX emission of 1047ppm at 220 bar injection pressure and 75% Load. Advancing the injection is proved to be advantageous because of longer residence time and complete combustion with thermal efficiency of the order of 37%, but it also causes higher NOX and soot emissions. Blend is restricted to 25% due to low cetane number of biodiesel which causes severe knocking problem at higher blends. Due to high NOX emission with the blend (B25), NOX mitigation technique like hot EGR is adopted to the extents of 5% and 10%.Finally, it is concluded that blending up to25% can be adopted with 10% EGR at 220 bar injection pressure with 27obTDCinjection timing for better performance, combustion and emission characteristics.
Structure Property Correlation of Friction Stir Welded Al-Ce-Si-Mg Aluminium Alloy and Optimization of Process Parameters using Soft Computing Techniques
(National Institute of Technology Karnataka, Surathkal, 2021) D’souza, Austine Dinesh.; Rao, Shrikantha S.; Herbert, Mervin A.
The demand for Aluminium alloys for uses as structural material is growing day by day, due to their distinct benefit of high strength to weight ratio. However, these alloys show a great challenge during welding by conventional methods due to the physical properties being dissimilar to steel and other materials and the property of improved hardness. Solid state welding method offers an alternative to conventional welding methods and leads to the improved joint efficiency due to microstructural alteration. Researchers around the world are carrying out wide-ranging experiments on one such process known as Friction Stir welding or FSW to join the materials effectively in solid state. In the present research study, the evolution of microstructure at the weld zone during friction stir welding of Al-Ce-Si-Mg aluminium alloy (Al-10Mg-8Ce-3.5Si and Al-5Mg-8Ce-3.5Si), as well as the effect of Friction Stir Welding (FSW) on joint strength was carried out. The microstructural study of the FSW joint has been carried out using Scanning electron microscopy as per ASTM E112-12(2012). An EDAX analysis as per ASTM F1375-92(2012) and an Optical emission spectrometry as per ASTM E1251-11 have been carried out to ascertain the chemical composition. An x-ray diffraction has been carried out as per ASTM F2024 - 10(2016) to ascertain the phases present in the alloy. The tensile testing has been done as per ASTM E8-04 and Vickers hardness test as per ASTM E92–17. It is very difficult to identify the process variables to obtain the desired joint strength by conducting numerous individual experiments. Therefore, to analyse the welding process variables, the orthogonal array technique (OA) type Taguchi design of experiment helps in arriving at the best possible solution. Design of Experiments were adopted to find out the influence of various input process parameters on mechanical properties such as ultimate tensile strength (UTS), hardness and grain size of the joint and to predict the UTS of the joint. The Taguchi experiments showed that the tool pin shape, speed of tool rotation and speed of welding have a bearing on the quality of the FSW joints in aluminium alloys. It was observed that the grain size at Nugget Zone (NZ) is dependent on the speed of tool rotation, speed of welding, tool pin shape and composition of the aluminium alloy. The grain size at the bottom of the NZ was found to be decreasing as compared to the top of the NZ. It was observed that highest hardness was found at NZ. Minimum hardness was obtained at HAZ and all the tensile specimens fractured at HAZ. Optimal joint strength was obtained for a speed of tool rotation of 1000 rpm, speed of welding of 20 mm/min, tool of triangular pin shape and 10% (wt%) of Mg (Al-10Mg-8Ce-3.5Si) aluminium alloy. The Taguchi orthogonal array-based design has shown that the Tool pin shape has greater significance in increasing the joint strength, followed by speed of welding, Material composition and speed of tool rotation. A speed of tool rotation 1000rpm, speed of welding 20 mm/min, Triangular Profile Tool (TPP) tool and Al-10Mg-8Ce-3.5Si aluminium alloy were obtained as the optimum variables of the process. The percentage contribution of each of the input process variables on optimum output quality characteristics was also found out and found to be lying well within the confidence interval of 95% suggested by the Taguchi design. Further work is carried out to predict the model for aluminium alloy joints fabricated using friction stir welding using Artificial neural network (ANN) technique. The Multilayer perceptron neural network (MLP) with error back propagation learning algorithm is selected as it can predict the ultimate tensile strength, percentage of elongation and hardness of the joint for given rotation speed welding speed, tool pin profile and composition of the material. The validation of the predicted model is performed by conducting validation experiments. The prediction is done by the model, and later it is analysed to assist the suitability of the ANN prediction model. The present work has shown that the prediction results with ANN are more superior to those predicted using statistical methods like Taguchi Techniques.
A Study on Performance Enhancement of Cutting Tools through Perforated Surface for the Machining of Titanium Alloy using PCD Inserts
(National Institute of Technology Karnataka, Surathkal, 2019) Rao, Charitha M.; Rao, Shrikantha S.; Herbert, Mervin A.
In the manufacturing industry, high-speed machining technology has been widely used in metal cutting due to its remarkable advantages in improving the productivity. However, the cutting tools have minimum tool life when used for machining difficult-to-cut materials such as titanium alloys and nickel-based alloys. Titanium alloy (Ti-6Al-4V alloy) is one of the widely used materials in the application of aerospace industries, military applications, automobile industries and biomedical implants. Rapid tool wear is the main issue in machining these difficult-to-cut materials due to the high heat generation in the machining zone and high chemical reactivity at higher cutting conditions. The heat produced at shear zone during machining of Ti-6Al-4V alloy is highly centralized and temperature increases rapidly. Tribological properties at the toolchip contact area can be improved by using a number of methods like Minimum Quantity Lubrication (MQL) and surface coatings. The surface texturing technology is a promising approach in this regard. Many researchers have discussed with different surface texturing patterns such as parallel, perpendicular and elliptical micro/nano textures on cutting inserts. These surface textures helped in improving the tribological properties. The present work is focused on surface textures with micro-hole patterns on cutting inserts, under the MQL environment. In this process, the lubricant surrounded in the micro-holes at the tool-chip interface could be squeezed to the cutting interface to reduce friction under proper viscosity and sliding speed. A novel configuration of holes and tunnels in the inserts has been tried out successfully. The present work is divided into three phases while machining of Ti-6Al- 4V alloy using the micro-hole patterned cutting insert under MQL environment. In the first phase, the modelling and simulation of micro-hole patterned cutting inserts were developed using Finite Element Analysis software. In this phase, different micro-hole patterns were developed on PolyCrystalline Diamond (PCD) cutting insert using CAD modelling and later static and dynamic analysis were carried out. From the results, it was observed that cutting inserts with micro-holes embedded on rake face and flank face had lower stress concentration. Hence, proved that cutting inserts with micro-holes withdifferent hole configurations had no adverse impact on mechanical properties of cutting tool materials. In the second phase, optimization strategy is applied to identify the right configuration of surface texture and experiments were conducted based on the one factor at a time approach to study the behaviour of individual process parameters like cutting velocity, feed rate and depth of cut on the performance indexes such as cutting temperature, machining vibrations, tool flank wear, Material Removal Rate (MRR), chip-morphology and surface integrity (surface roughness, surface topography and microhardness) under MQL environment machining using normal and modified cutting inserts. It is evident from the experimental results that machining with modified inserts significantly improved the machining performance and quality of the product. One more finding, out of the present work, is the mitigation of serrated chips, when compared to chip formation in machining of Ti-6Al-4V alloys with normal inserts. The chip formation with less shear bands were obtained during machining process due to the improvement in the thermal stability property caused by a reduction in cutting temperature through micro-hole patterns. A best feasible micro-hole configuration for the machining of Ti-6Al-4V alloy under MQL environment was arrived at, as a unique solution. In the third phase, the modified PCD insert with the chosen pattern of micro-holes was compared with Polycrystalline Cubic Boron Nitride (PCBN) inserts, for machining of the Ti-6Al-4V alloy. From the experimental results, it was found that modified PCD insert had better efficiency in reducing the cutting temperatures and also reduces the tool wear by increasing the wear resistance properties due to the micro-pool lubrications when compared to modified PCBN inserts. Another important outcome of this research is the development of prediction model using Adaptive Neuro-Fuzzy Inference System (ANFIS) to assist in validation. This method is a combination of two soft-computing methods of ANN and Fuzzy logic. Fuzzy logic helps in the transformation of the human knowledge and the ANN helps in the learning process and reduces the rate of errors in the determination of rules in fuzzy logic. In this research, gauss membership function model was developed for the prediction ofoutput parameters. The comparison made between the predicted values derived from ANFIS and experimental values proved that the gauss membership function adaptation achieved accuracy of 96 % with 4-5% prediction error. Thus, a unique surface texturing consisting of micro-holes and tunnels in the PCD inserts, for machining Ti-6Al-4V alloy has been successfully developed, tested and validated.