2. Thesis and Dissertations
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Item Modelling and Validation of Behaviour of Mushy State Rolled Al-4.5Cu-5TiB2 Composite using Neural Network Techniques(National Institute of Technology Karnataka, Surathkal, 2013) Vithal, Nigalye Akshay; Herbert, M. A.; Rao, S. S.Aluminium alloy matrix composites reinforced with in situ formed TiB2 particles are found to possess excellent mechanical properties as well as high stability at elevated temperatures. Forming of these composites by conventional methods is difficult due to their tendency of cracking. The problem is overcome by subjecting these composites to mushy state forming. Studies on mushy state rolling of Al-4.5Cu-5TiB2 composite have witnessed formation of bimodal equiaxed grains having spheroidal morphology from one that is essentially dendritic in as cast condition. Resulting mechanical and wear properties of mushy state rolled Al-4.5Cu-5TiB2 composite are also observed to be superior to that of as cast composite. The data on the grain sizes, hardness, wear and tensile properties of mushy state rolled composite has been expanded by using neural network techniques. This is done to have better understanding of the relationship between mushy state rolling process parameters and the resulting mechanical and wear properties. Artificial Neural Networks with feed forward architecture, and trained using backpropagation algorithm have been used to predict bimodal grain sizes, hardness, tensile and wear properties of Al-4.5Cu-5TiB2 composite rolled from mushy state in as cast and in pre hot rolled condition. The models have been validated by conducting mushy state rolling experiments. The composite samples in as cast and in pre hot rolled condition are mushy state rolled at pre set points within and outside the bounds of data used for training the ANN models. The validity of the models is established by way of comparison of the validation experiment results with the values predicted by models. The ANN models formulated for grain size, hardness, wear and tensile properties prediction are found to predict the corresponding outputs quite accurately, within the acceptable limits of prediction errors. Artificial Neural Networks though known for non linear mapping of complex systems, are static mapping tools in the sense that the knowledge update is based on static data provided for training the network. Simple recurrent neural networks (SRN) such as the one proposed by Elman have the capacity of dynamic learning. Thecomputational power of Elman networks has been thought to be comparable to that of finite state machines. However, such extended simple recurrent neural networks when adopted, are found to possess severely hampered learning capabilities due to convergence problems. A novel way of overcoming the problem of convergence is proposed through this work by using a Hybrid Recurrent Neural Network (HRNN) modelled from an ANN. The HRNN is modelled by borrowing weights into an Elman Simple Recurrent Neural Network having similar architecture (devoid of context layers). Such an HRNN formulated is found to converge excellently in a significantly less time as compared to an ANN for the same value of preset MSE. The prediction errors of HRNN and prediction errors resulting from ANN predictions when subjected to statistical testing are found to be equivalent. The predictions resulting from HRNNs modelled for prediction of duplex grain sizes, hardness, tensile and wear properties are seen to be in close agreement with the predictions made by the ANN models. However, it is seen that the overall time required for training HRNNs which includes the time required for training of partially trained ANNs, is significantly reduced. Thus it is observed that an HRNN modelled from a partially trained ANN has equivalent prediction capability and is superior to ANN in terms of computational time. Graphical user interface (GUI) has been designed using available API libraries which include two main modules, namely, ANN and RNN. Each model has the sub components for prediction of grain size, hardness, wear rate and tensile properties. There is provision to obtain outputs by manually feeding the input values as well for plotting line graphs by varying one parameter at a time, keeping other parameters constant. The GUI is also designed to generate bar plots by varying each mushy state processing input parameter at a time. Use of GUI is made in optimising the mushy state processing parameters for obtaining the best possible hardness values and minimum wear rate for mushy state rolled Al-4.5Cu-5TiB2 composite.Item Development and Characterization of Functionally Graded Al-Si Alloy System and Al-Si/SiCP Composites using Centrifuge Casting(National Institute of Technology Karnataka, Surathkal, 2013) S., Kiran Aithal; Desai, Vijay; Narendranath, S.FGM is a material that shows change in magnitude of property values from one end of a specimen or component to the other end. FGM has an intermediate layer whose structure, composition and morphology vary smoothly from one end of the specimen to the other end. Fabrication of FGM and their components with gradient microstructures and properties are challenging. Most of the investigations which focus on material behavior of FGMs are limited to analytical or numerical studies. One of the major bottlenecks with experimental studies is the preparation of FGMs having large property gradation. This necessitates the development of a suitable technique to produce such FGMs with reproducibility of structure and properties. The present work aims at developing a manufacturing technique for the FGMs in order to meet the wide range of and also suitable mechanical and tribological properties for specific thermal and mechanical engineering applications. Among the processing techniques available the most commonly used is horizontal centrifugal method, but, this method is used to produce mainly hallow cylinders. In this work a centrifuge setup is fabricated and FGMs have been successfully developed to produce solid castings. The major advantage of this machine when compared to the conventional machine is that the pouring is done while the mold is stationary and machine operates about a vertical axis. The principal advantage of this is good mold filling combined with microstructural control, which usually results in improved mechanical properties. In this process, when the melt is subjected to high G forces the lighter particles segregate towards the axis of rotation, while the denser particles move away from the axis of rotation depending on the density difference between melt and the reinforcement. This segregation depends on several process parameters such as mold rotational speed (G Factor), pouring temperature, mold temperature etc. The use of aluminum, its alloys and aluminum based composites in the present day has shown many advantages through its unique combination of physical and mechanical properties. The light weight, strength, formability, corrosion resistance, ofIV aluminum, its alloys give it the potential to meet a wide range of design challenges. Taking into consideration the advantages such as high wear resistance, controlled thermal-expansion coefficient, good corrosion resistance, and improved mechanical properties over a range of temperatures that Al alloys and its composites can provide, in this work manufacturing and characterization Al-Si FG alloys and Al-Si-SiCP FG composites have been taken up. Two Al-Si alloys eutectic (12%Si) and hypereutectic (17%Si) were used for producing FG alloys. Further effect of 3 mold rotational speed 200, 300, 400rpm, 2 pouring temperatures 800oC , 900oC and 2 mold temperatures ambient and preheating the mold at 180oC temperature were studied. Similarly FG composites were also produced using Al-17%Si and Al-12% Si as matrix with SiCP as reinforcement. Three different volume fractions of SiCP were used to produce FG composites. The FG composites were produced using 900oC pouring temperature with preheating the mold at 180oC under 200, 300, 400rpm mold rotational speed. The structure and properties of the FG alloys and Composites are studied to understand the effect of different process parameters. The Al-Si FGM specimens are studied for distribution of Si along the length of the specimen (from bottom to top) using optical microscope. The hardness's is measured along the length of the specimen using Brinell hardness tester. Sliding wear tests at room temperature are conducted at normal loads of 40, 60, and 80N and at 1.466m/s sliding speed for a constant sliding distance 879.6m in order to measure the wear resistance and friction characteristics. Similar tests were carried out for FG composites. Diametral compressive strength were conducted to know the strength of the specimen along the length at bottom, middle and top regions. It is found that the FG alloy and Composites are produced successfully using centrifuge technique. In both alloy and composite the gradation occurs at higher rpm, teeming temperature and mold temperature. The experimental findings of hardness and the wear tests provide adequate proof on the gradation characterization (% volume fraction of primary Si, % volume fraction of SiCP and rim thickness) done using microstructural studies.Item Performance Evaluation of Power Transmission Line Tower Made of Polymer Matrix Composite(National Institute of Technology Karnataka, Surathkal, 2013) M., Selvaraj; Kulkarni, S. M.; Ramesh Babu, R.The design of power transmission lines is done to meet multiple constraints – electrical, mechanical and environmental. Thus designers are generous in deciding the margin to meet the above. But presently, with limited space for transmission lines, need for reduction in transmission line space in both horizontal i.e., Right of Way (ROW) and vertical i.e., height of tower has arisen. Several attempts are made to achieve this reduction at the same time reducing the cost. Use of composites for tower and its components is an attempt directed to decrease the space and the cost. Polymer composite materials have emerged as promising engineering materials due to their light weight and non – corrosiveness. The available literature provide few details of polymer matrix composites as alternative materials for tower but a systematic and holistic study on developing and testing of a tower with composites is yet to see the light. Thus, the present work is focused on development of a tower with composite members and test it for meeting mechanical and electrical performances and also achieve reduction in ROW and cost. The work considers two approaches, first is FE analysis and the next is physical building of tower components at different levels and the full tower to test for the performance. As a preliminary step, properties of glassepoxy material processed with pultrusion are determined to assess its suitability in tower applications. Subsequently, various tower members are fabricated with pultrusion process the details of which are provided in Table.1 The tower considered for present work is a 66 kV vertical double circuit lattice type in a line of 200m span operating at a wind speed of 47 m/s. Initially tower and its components are designed as suggested in standard IS: 802 providing all mandatory clearances from the point of electrical insulation. Cross arm which is one of the major components in tower, is modelled in FEM using dimensions determined earlier. The design of cross arm is verified with FE analysis. Subsequently, FE analysis of a portion of the tower body, tower sub assembly, followed by analysis with cross arm mounted is taken up. FE analysis of a full length tower made of composite member is envisaged as an ultimate part of the study.Analysis indicated that stress levels in members far below the permissible ones of a material. Thus design of tower and its components is verified. Table 1. Details of GE pultruded cross arm and tower members Sl. No Member Dimensions of member cross section Reinforcement Matrix 1 Solid rectangle section 20 mm x 70 mm E- Glass continuous fibres ( 70 - 75 % ) Epoxy (20-25%) Lapox L-12 Hardener K-6 2 Solid angle section 50x50x6mm 76.2 x 76.2x6.35 - do- - do- 3 Solid circular section Ø30 mm, Ø33 mm - do- - do- 4 Hollow sections 101.6x101.6x9.525 101.6x101.6x6.35 - do- - doIn order to reinforce the feasibility of tower with composite material, physical construction and testing of its components and in the end full tower is taken up. All tests are carried out at station in Central Power Research Institute (CPRI), Bangalore. Initially cross arm is constructed and loads as suggested in standard IS: 802 are applied on the cross arm. The deflection measured at the tip of cross arm is only about 44 mm also strains in members of the cross arm are found to be not vey excessive. Prototype testing is extended to a tower sub assembly without cross arm and with cross arm mounted successfully. Later a full length tower with all cross arms mounted in place is constructed and tested. The tower with composite member performed satisfactorily without any visible damage at 100 % full load suggested in standard. The maximum deflection of tower is found to be only 1.4 % of tower height and is within permissible limit of 5 %. The tower with composite member successfully withstood even 300 % full load without any visible signs of failure suggesting a Factor of safety 3.0.Tests for electrical performance of cross arm and tower with composite members are carried out. Table.2 provides the results of electrical test wherein it can be observed that the test parameters determined are higher than the suggested minimum values. Thus the cross arm and tower satisfactorily meet the electrical requirements. Table 2. Results of electrical testing Electrical Performance test Suggested minimum values in IS:2165 Experimentally determined values Cross arm with tower sub-assembly Full tower Power frequency ( kV ) 140 150 143 Impulse voltage ( kV ) 325 328 328 From the study it could be inferred that the tower with composite members satisfied both mechanical and electrical requirements. Since the tower is without insulator strings and the associated problems of their swing, the ROW for the line is less and a saving of about 17 % is achieved in ROW. The height of the proposed tower is only 15 m as against 18 m for metallic tower suggested by Indian standard IS: 5613. Thus a saving of about 18 % is achieved. Consequently on account of this lesser height and lower weight of composite members, the saving in total weight of the tower against a metallic tower is about 33 %. Thus with savings and benefits mentioned above, the proposed tower could be most suitable for earthquake prone zones and for Emergency Restoration Systems (ERS).Item Studies on The Performance, Combustion & Emission Characteristics of A Multicylinder Si Engine Fueled with lpg Along with Varying Steam Induction Rates(National Institute of Technology Karnataka, Surathkal, 2013) K. S, Shankar; Mohanan, PVehicle and fuel technologies have undergone important developments in the last 30 years. The volatility of oil prices and increasing concerns about the environment has influenced researchers to look in to possible alternatives to petroleum based fuels. Efforts are on to improve the combustion efficiency of the engines operating with conventional fuels. The various alternative fuels for spark ignition (SI) engines on which research is going on at present includes alcohols, liquefied petroleum gas (LPG), natural gas etc. Ethanol enriched gasoline blends are increasingly being used in SI engines due to the renewable nature of ethanol as well as increased governmental regulatory mandates. Ethanol can be produced from natural products or waste materials, compared with gasoline which is produced from non-renewable natural sources. In addition, ethanol shows good antiknock characteristics. Gaseous fuels are promising alternative fuels due to their economical costs, high octane numbers, higher heating values and lower polluting exhaust emissions. From the point of view of reduction of exhaust emissions such as unburnt hydrocarbon (HC) and carbon monoxide (CO), liquefied petroleum gas (LPG) is a useful alternative fuel for SI engines. Due to its higher octane value, LPG fuel can be used under the higher compression ratios. Combustion of LPG results in greater emissions of the oxides of nitrogen (NOX) than that for gasoline, the values reaching more than double at some operating conditions. Injection of water into the intake manifold has been found to be an effective way to reduce NOX emission in SI, CI and LPG engines. The present study deals with experimental investigations on the effect of steam induction with the intake air while using LPG as fuel on engine performance, combustion and emissions in a modified multi-cylinder SI engine. The engine operating parameters of speed, throttle opening positions and static ignition timings are varied. To compare the results of the above experiments, an ethanol enriched gasoline blend is optimized as a baseline fuel based on engine performance, combustion and emissions. The experimental setup consists of a stationary, fourstroke, four cylinder, multipoint port fuel injection (MPFI) engine of 44 kW capacity at 6000 rpm, which is connected to an eddy current dynamometer for loading. A piezo-electric pressure transducer is used for recording the cylinder pressure. The setup has a stand-alone panel box consisting of air box, fuel tank, manometer, fuel measuring unit, differential pressure transmitters for air and fuel flow measurements, process indicator and engine indicator. An AVL Digas 444 five gas Exhaust gas analyzer is used to measure the NOX (ppm), CO (%vol.), CO2 (%vol.) and HC (ppm) emissions in the exhaust. Initially experiments are conducted to study the performance, combustion and emission characteristics of the test engine fueled with ethanol enriched gasoline blends viz: E5, E10, E15 and E20 (on volume basis, and E5 means 5% ethanol and 95% gasoline) to optimize a baseline fuel. In the next part tests are conducted on the engine modified to run with injection of LPG as fuel and the combustion, performance and emission characteristics are evaluated. Separate four gas injectors are installed in the inlet manifold near the inlet port of each cylinder for injecting LPG. The gas injectors are operated by solenoid valves driven by 12V DC power supply. A separate gas ECU has been used for driving the solenoid valves. Experiments are conducted at wide open throttle (WOT) and part throttle conditions with varying loads in the engine speed range of 2000 rpm to 4500 rpm. Tests with ethanol enriched gasoline are conducted at the pre-set static ignition timing of 5 degree before top dead center (bTDC). The LPG performance and emissions are evaluated at various static ignition timings of 3, 4, 5 and 6 deg. bDTC. In the last part of the investigations, the engine tests are conducted with LPG along with steam induction. The waste heat from the exhaust gas has been used to generate steam from deionized water. Steam to LPG flow rates of 10, 15, 20 and 25% (on mass basis) are used. The steam is mixed with the intake air in the intake manifold of the engine. Results of the experiments have shown that among the various ethanol enriched blends, the blend of 20% ethanol was the most suitable one from the engine performance and CO & HC emissions points of view. At WOT operations the effect of ethanol blending on coefficient of variation of IMEP is to reduce it by an average of 2% with E15 fuel blend when compared to gasoline fuel operation over the entire speed range. All the ethanol-gasoline blends exhibit better cyclic variation pattern compared to gasoline at WOT operation. The engine performance has improved with the addition of ethanol, increasing the thermal efficiency and reducing the brakespecific energy consumption. A significant reduction in the HC emission was observed as a result of leaning effect and additional fuel oxygen caused by the ethanol addition. CO emission is reduced by addition of ethanol to gasoline. All engine exhaust emissions were lower at 3500-4000 rpm at various throttle valve opening condition except NOX which has shown an increasing trend with ethanol blended fuel. Hence it can be concluded that blending ethanol up to 20% to gasoline will reduce the cycle-by-cycle combustion variations and emissions though a marginal increase in NOX emissions results. The findings of the experiments with LPG suggest that higher thermal efficiency and therefore improved fuel economy can be obtained from SI engines running on LPG as against gasoline at the pre-set static ignition timing of 5 deg. bTDC. Also the exhaust emissions of CO, HC have reduced considerably. But the emissions of NOX have increased significantly at higher engine speeds. The CO emission has reduced from an average value of 5 % to about 1.3 % and corresponding change in HC noticed was from 350 ppm to 22 ppm when LPG was used instead of gasoline at pre-set static ignition timing. The NOX emission with LPG was almost double when compared to that with gasoline at higher engine speeds. When engine runs with LPG, better performance has been observed when static ignition timing is advanced to 6 deg. bTDC. Advancing the static ignition timing has also resulted in reduced CO and HC emissions. But the advanced ignition timing shows a further increase in NOX emissions. Retarding the ignition timing achieves lesser NOX emissions at higher engine speeds. Steam induction is one of the methods to reduce NOX emissions. Steam induction will reduce the peak temperature of the engine cylinder so that NOX formation will be reduced. The experimental results showed that steam induction worked as a cooling means for the fuel-air charge and slowing the burning rates, resulting in reduction of the peak combustion temperature. It is found that NOX emissions have reduced significantly by 20 - 45% over the entire operating range when compared to LPG operation. No considerable changes in CO and HC emissions are observed. Hence use of LPG with advanced ignition timing of 6deg. bTDC with steam induction up to 25% steam to fuel mass ratio at higher engine speeds and up to 10% steam to fuel massratio at lower engine speeds can be used from the point of view of improved engine performance and reduced exhaust emissions. When comparing the performance and emissions of ethanol enriched gasoline and LPG with steam induction, it is noted that, comparatively E20 blends performs better that LPG alone. With steam induction the performance with LPG deteriorates. The brake thermal efficiency of 15% steam with LPG at wide open throttle condition and 3500 rpm is lower by 3.5% when compared to E20. CO reduces with LPG when compared to E20. But a slight increment is noted when steam is inducted. NOX emissions are higher for both E20 and LPG when compared to gasoline. However, with the induction of steam along with LPG, the NOX can be substantially brought down. At 3500 rpm and wide open throttle condition, the NOX emissions of E20 and 15% steam with LPG are similar. But at 4500 rpm, NOX emission is higher by 580 ppm. From the experimental investigations it can be concluded that use of ethanol enriched blends in unmodified engine is an alternative for the use of gasoline as a sole fuel. However with the current option of LPG as alternative fuel to SI engines, it can be used along with steam induction as a means to considerably reduce NOX emissions, with marginal reduction in engine performanceItem Performance Evaluation and Optimisation of Surface Grinding Process for Grinding of Aluminium Based Metal Matrix Composites using Response Surface Methodology and A Novel Genetic Algorithm Approach(National Institute of Technology Karnataka, Surathkal, 2013) K., Dayananda Pai; Rao, Shrikantha S.Aluminium-based metal matrix composites (MMCs) reinforced with ceramic particles are the advanced materials known for their good damping properties, high specific strength and high wear resistance. MMCs are increasingly used in aeronautical and automobile industries and in military applications. In addition, the sporting goods industry has also been in the forefront of MMCs development to capitalise on the materials high specific properties. Despite many advantages, full implementation of MMCs is cost-prohibitive. This is partially due to the poor machinability of the materials. Although near-netshape MMC components can be produced, finishing is still required for obtaining the desired dimensional accuracy and surface finish. Significant cost and fabrication problems, including machining, must be overcome for the successful application of these composites. Surface finish and surface integrity are important for surface sensitive parts subjected to fatigue. Unconventional processes produce better surface finish but they results in subsurface damage during the machining of MMCs. Hence, finishing processes such as grinding and allied abrasive machining are used to improve the surface integrity of machined MMCs. The grindability of aluminium-based MMCs reinforced with ceramic particles is investigated in this dissertation. By the analysis of variance, a complete realization of the grinding process and their effects was achieved. Mathematical model is established for specific energy, metal removal rate and surface roughness from Response surface methodology (RSM). The main objective of this research is to determine the favourable grinding conditions for aluminium-based MMCs reinforced with ceramic particles. Not many researchers have attempted the optimisation of the surface grinding process by considering the specific energy as a performance parameter during grinding of MMCs. A novel approach of multi-objective optimization based on Genetic Algorithm and Desirability function approach was conducted to achieve the desired objective. Very few research works have been attempted towards multi objective optimisation involving surface roughness, metal removal rate and specific energy as the performance parameters in total. The first part of the presented research concentrates on influence of process variables on specific energy, metal removal rate and surface roughness obtained ingrinding of Al6061-SiC35P composites using Taguchi’s design of experiments. From the above investigation, it is observed that feed is the dominant factor affecting the specific energy. Depth of cut is the dominant factor affecting the Metal removal rate and volume percentage of SiC is the dominant factor affecting the surface roughness. The second part of presented research concentrates on mathematical modelling RSM. From the study, it is revealed that the second order RSM model developed for the performance parameters indicates good fit with the experimental results. Desirability function approach for multi-objective optimisation is adopted to choose the process variables that are favourable to achieve the optimal values of specific energy, metal removal rate and surface roughness. The third part of the research involves the application of novel genetic algorithm on multi objective optimisation of specific energy (u), metal removal rate (Qw) and surface roughness (Ra). The results obtained from this novel genetic algorithm were compared with RSM and the results obtained were in fairly close agreement. Finally, the confirmatory experiments were carried out to validate the results obtained from RSM and novel genetic algorithm. From the experiments, it was observed that, deviation between the experimental and predicted responses were within 14%. However novel genetic algorithm compilation consumes less amount time in comparison to conventional non-dominated genetic algorithm (NSGA-II). Hence from the study, it can be concluded that the developed novel genetic algorithm model can be effectively used for the prediction of specific energy, metal removal rate and surface roughness. The understanding gained from Taguchi’s design of experiments, RSM, Desirability function approach and novel genetic algorithm in this research can be used to develop future guidelines for grinding of aluminium-based MMCs reinforced with ceramic particles.Item Fluid and Thermal Induced Vibration in Thin Slender Tube(National Institute of Technology Karnataka, Surathkal, 2013) Marakala, Narasimha; K. K., Appu Kuttan; Kadoli, RavikiranThin beam and thin walled circular tubes are widely found in various structural engineering applications. For example, satellites, rockets where the propellant is transferred through connecting pipe lines, micro heat exchanger pipe used in refrigeration and air conditioning system, air craft fuel ducts, etc. Invariably the structure experiences fluid load due to inertia effect of the fluid, thermal loads due to heat conduction and convection and dynamic loads due to inertia effect of the structural element. The pipelines conveying high velocity internal flow may experience severe flow induced vibration due to fluid pipeline interaction. Therefore response of the pipe to fluid load and inertia load is very important for the safe design and operation. The present study is focused on the dynamic response of slender cantilever pipe oriented in the horizontal and vertical direction conveying air at different pressure. The objective of this work is to formulate the equation of motion using Newtonian’s approach and finite element solution of this equation that helps to study the effect of boundary conditions, flow velocity, fluid pressure on the free vibration characteristics of the cantilevered pipe conveying air. The FORTRAN codes are written based on the finite element formulation. This code is validated with problems reported in archival journals. The experimental set-up was fabricated in the laboratory and experiments were conducted to study the response of the cantilever tube in horizontal and vertical orientation at different lengths, conveying air with different pressure. Certain important observations which are concluded from this work are (i) increasing the length of cantilever tube will increase the amplitude of transverse displacement and decrease the fundamental frequency of tube, irrespective of its orientation and (ii) increasing the pressure will increase amplitude of transverse response of cantilever tube and but the frequency remains same. These experimental observations are compared with the numerically obtained results. To understand the thermally induced oscillations, it is essential to solve the heat transfer and structural problems simultaneously by coupling the temperature distribution and the structural displacement. The second order linear differential equation of motion with damping and thermal load as forcing function is presented. In the present study, spatial and time variation of convection that arises due to motion of beam is interpreted based on the physical understanding of the nature of air currents that are established due to motion of tube. Thus, the forced convective heat transfer coefficient is computed using Reynold’s number, Prandlt number and Nusselt number. Fourth order Runge-Kutta method is used to determine the transient response of the tube being subjected to heat source. The dynamic response of the tube is studied for various heating rates and different diameters of tube. The analysis showed that the rate of vibration is governed by the natural frequency of the tube and convective heat transfer coefficient. The displacement histories, which were initiated due to initial displacement, with the passage of time exhibited an initial decrease in the displacement and gradually increased to a maximum value depending on the heating rate and the magnitude of the sustained oscillations, were governed by the fact that the heat removed by convection balance the internal heating. Experimental studies were also carried out on thermally induced vibration of internally heated cantilever tube with tip mass and cantilevered U-tube with and without tip mass. The experimental results on the displacement response are found to agree reasonably well with the theoretical results. The important observations from the study conducted were, lowering the heating rate leading to larger time to attain steady state amplitude and vice- versa and also there exists a threshold heating rate to produce thermal induced motion for the tube. According to available literature, combined effect of fluid flow and thermal effect on the vibration of pipe has not been studied rigorously. In the present work, experimental and theoretical study of fluid and thermal induced vibration has been carried out on thin tube. The experiments are conducted for different end mass, length of the tube as well as the air passing through the tube at different temperature and pressure. The natural frequencies are calculated theoretically using finite element formulation and compared with the experimental results. It is observed from the study that the increase in pressure tends to increase the frequency due to increase in stiffness and increase in temperature tends to decrease the frequency due to softening effect of tube.Item Machinability Studies on Carbon and Alloy Steels using Face Turning(National Institute of Technology Karnataka, Surathkal, 2014) Shankar, Lalbondre Rajshekhar; Mohan Kumar, G. C.; Krishna, PrasadThe present study is an experimental investigation on the machinability of carbon and alloy steels by face turning method. This study finds its usefulness in economic machining solution to fulfil the local objectives of knowing, in advance, the machinability of selected carbon and alloy steel material of grade: AISI-1050, AISI- 51100, AISI-52100, AISI-4320 and AISI-9320. The face turning method makes use of cylindrical steel bar specimen as test pieces for testing the machinability of the steels. The technical effectivity of the face turning method is assessed by studying: the cutting time required for the tool to reach flank wear upto 0.3mm (tool life criterion); tool wear development and wear mechanisms involved in machining; tool life studies and machinability indices of the work-material; surface roughness and microhardness investigations (SEM) of the machined surfaces; and chip morphology and crater wear studies. These aspects are further tested and verified for its repeatability and reproducibility. The tests are being carried according to some of the guidelines laid in the international standards, ISO 3685:1993(E) and American Foundry Society (AFS) standard machinability tests. The results presented here demonstrate the ability of the face turning method to assess the tool wear development while machining different work-materials; to evaluate the tool life for each of the work-material under consideration; to differentiate very distinctly and rank these materials according to their machinability; to investigate surface finish due to tool wear and micro-hardness of the machined surface generated after the tool wear reached its tool life criterion; to analyse the chip morphologies with crater wear; and to overall characterize the machinability of steels under consideration. The face turning method used here is simple and effective for the given tool-work material pair.Item Investigation on Mechanical and Wear Properties of Composites from Recycled Polymer for Gears with Optimized Compression Moulding(National Institute of Technology Karnataka, Surathkal, 2014) Prabhu, B Krishna.; Kulkarni, S. M.Cost of a product can be visualized as sum of the cost of materials and process cost. In a competitive world, producing quality products at low cost is need of the day. In reducing the process cost, the use of off line techniques like Design for manufacturing (DFM), design of experiments (DOE), Six Sigma optimization and process modeling could be adopted. Further, judicious development of low cost materials, will help in bringing down the total cost of the product. In view that polymer consumption is growing at a fast pace, reusing post consumer polymers could help reducing the material cost component of the product. Recycling engineering plastic such as post consumed Polyethylene Terephthalate (PET) provides not only a cheap and abundantly available source of material but also expands the sphere of application for recycled PET (r-PET). However, owing to reduction in the properties due to recycling procedures, the plastic need to be developed suitably, to meet the requirements of an application. Reinforcing r-PET with suitable material could address this issue. Fly ash cenospheres are low cost material that could be useful in improving the properties of recycled polymers. The cost of the product developed from low cost recycled materials could be further reduced by developing suitable low cost process. Compression moulding could be a low cost process. The process however needs to be optimized for moulding product with appreciable quality. Thus the present study is focused on developing r-PET based composites with FA cenospheres as reinforcement and compression moulding as a manufacturing process in order to cater the requirements of an industry to produce low cost engineering components such as gears. In the process of optimization, Six Sigma based DMAIC/DMADV methodology along with Taguchi’s method and RSM are utilized where as development of r-PET/FAC composite is carried out using design of experiments (DOE). Entire work is envisaged in five stages. The first stage of the experimentation is carried out with an intention to establish a thermo-mechanical moulding process for r-PET. Six Sigma DMADV methodology is utilized along with Failure Modes and Effects Analysis (FMEA) for successive improvement in the moulding procedure. A reduction in risk priority number (RPN) from 900 to 315 and finally to 8 is achieved on successive improvement in the process using FMEA. At the end of its successful application, a good, repeatable sample quality is achieved. In the second stage, R-PET, reinforced with FAC is studied for a set of compression moulding process variables and material variables using DOE as statistical tool. Five factors, critical to quality (CTQs) viz. moulding pressure (5, 10, 15 MPa); moulding time (5, 10, 15 min.); mould cooling (water, air, water and air); moulding temperature (50, 100, 150 ˚C) and weight fraction of cenospheres (5, 10, 15%), are considered at three levels. The DOE methodology adapted for such investigations showed a down ward trend for FAC content. The cause investigated using fractographic analysis, concludes debonding of FAC from the matrix due to improper interfacial characteristics. Further, the composite underwent brittle fracture making it not much useful for gear applications. The remedy considered for developing r-PET composite that makes it suitable for the gear application is to blend the matrix with an appropriate recycled polymer and to improve interfacial interactions of FAC with matrix by suitably treating FAC with (3-Aminopropyl) trimethoxy silane (3APTMS). The wear property of the composite however, proves promising as FAC reduced Specific wear rate (SWR). The preliminary work in developing the matrix, in the third stage, involves blending rPET with five softer polymers from recycled regime. R-LLDPE, r-LDPE, r-HDPE, r-PP and r-Nylon are these five polymers. Experimentation of r-PET blends suitably selects rLDPE as better suited polymer owing to its flexural and wear properties. . Blending rPET with 10% r-LDPE improves the toughness by 100% and by 112% at 30%. This is followed by r-HDPE that shows 25% and 100% increase at respective composition. Flexural strength and SWR of r-PET/r-LDPE blends affected marginally whencompared to the plastics considered in this study. The next part of third stage involves developing the composite with matrix blended with r-LDPE (30% by wt.), reinforced with FAC (5, 10, 15% by wt). An improvement in the fracture strain, over 87 % is noted at 30% of r-LDPE and 15% FAC. An improvement in toughness by about 66 MPa at 5% FAC and 13 MPa at 30% of FAC is observed. Thus studies on matrix blending conclude that blending r-PET with r-LDPE helps in reducing the brittleness of r-PET. Further, 3APTMS (6, 8, 10% by wt.) is used for treating FAC and to improve the interface. Reinforcing r-PET with 3APTMS (10% by wt.) treated FAC (T-FAC) improved flexural strength of r-PET/T-FAC composite. An increase of 34% strength at 5% T-FAC, 57% increase at 10% and 120% improvement in strength at 15 % of T-FAC is observed owing to surface treatments given to FAC. Such an increase in the properties leads to improvement in the toughness of the composite. Toughness improves by 95% at 5% of T-FAC, 200% at 10% and an increase of 271% in toughness when r-PET is reinforced with 15% T-FAC is observed. Owing to blending and treating of reinforcement, flexural and wears properties improved significantly. Further M-r-PET/T-FAC composite is also tested for their properties. The results of M-r-PET/T-FAC composite conclude favorably for developing low cost material from recycled means. In the next stage, the process and material thus developed are optimised for flexural and wear properties. In the fourth stage the process and material parameters are optimized for improved properties of the composite. Six Sigma DMAIC optimisation tool, Analysis of variance (ANOVA), Response surface methodology (RSM) are used to determine the optimum values. The final optimum parameters for moulding r-PET reinforced with FAC are Moulding pressure – 11.2 MPa, 3APTMS -7.9 % by wt., r-LDPE - 29 % by wt., moulding Temperature - 52.6 ºC and FAC – 12.5%. Confirmation experiments for these optimum values are done to verify the validity of the process adopted. In the fifth and final stage the material developed in the previous stages is moulded into gears with optimized compression moulding and their performance is evaluated on an indigenously designed and fabricated gear test rig. The increase in the gear life by about275% w. r .t the starting composite (r-PET/FAC) seems good for the applications sought for them. The gear can handle a load of about 30.5 N and can take about 50,000 revolutions. With such an improvement shown by the composite material developed in this work, it could be considered as an alternative to the existing gears made from neat polymers for lower loading applications. Thus the objectives set for this research work that to develop a low cost composite material from environment hazardous waste materials with optimized compression moulding for gear applications are met with the systematic application of Six Sigma methodologies as explained in this work.Item Experimental Investigation and Analysis of Maize Natural Fibre Composites for Structural Applications(National Institute of Technology Karnataka, Surathkal, 2014) Bavan D, Saravana; Mohan Kumar, G. C.; Krishna, PrasadNatural fibre composites are the recent upcoming materials used in structural and other general engineering applications. They are more popular because of their abundance, native state of recycle, eco friendliness and sustainable material features. Natural fibres as reinforcement in the composite materials have attained new interests to the global sustainable world. As the fossil fuels are depleting, it is the time to focus on alternative material that can compensate with the present synthetic world of composites. Major applications of these natural fibres are in the structural and automotive sectors. The research work is focused on study of maize fibres and their composites with matrix of thermoset polymer for structural applications processed through Vacuum Assisted Resin Transfer Molding (VARTM) and with hand lay-up methods. Maize composites, Hybrid Composites (maize and jute fabric of single and double layer), and Bio-composites are processed. Maize composites and Bio-composites were processed by VARTM technique. Sandwiched hybrid composites were fabricated by hand layup method. Physical, Chemical, Thermal, Mechanical and Surface characterization tests were carried out for the performance and analysis of maize fibre composites. Natural fibres of pulverized maize stalk and matrix with different weight fractions are considered for the present work. As natural fibres are hydrophilic, chemical treatment of the fibres are carried out in order to make hydrophobic. Work is also concentrated in processing maize stalk particles as fibre and expoxidized soy bean oil as matrix to obtain a bio-composite material. Finite element analysis is also carried out for thermal studies of composites with maize long fibres with few assumptions. The result shows that the fibre and matrix interactions are better and improved with the chemical treatment. Experimental and Finite element results are compared and the results are presented and discussed.Item Some Studies on Process Parameters in Centrifugal Casting(National Institute of Technology Karnataka, Surathkal, 2014) Madhusudhan; S, Narendranath; Mohan Kumar, G. C.In a centrifugal casting process, the fluid behavior of the melt plays an important role in determining the quality of the final products. There are many parameters which influence the centrifugal casting process namely pouring temperature of the melt, initial temperature of the mold, thermal conductivity of the mold material, rotational speed of the mold, size of the mold and time taken for pouring the melt into the mold, etc. Rotational speed of the mold is one such parameter amongst the important process variables which affect the rate of solidification of the molten metal. When the liquid is rotated in partially filled cylindrical mold at different rotational speeds, it exhibits various flow patterns, namely Ekmann flow, Couette flow and Taylor flow; these are disturbing flows inside the cylinder. A brief survey of the earlier literature indicates that many investigations have been carried out to study the behavior of the liquids and its effect on the casting process. The microstructures of the castings are influenced mainly by the behavior of molten metal flow during rotation of the mold. To get a uniform hollow cylinder, the molten metal must spread along the axis after being poured and must slide along the inner surface of the mold. But the factors involved in fluid instabilities that influence the quality of the casting and rate of cooling need to be investigated. The analysis of liquid flow during centrifugal casting is very difficult to comprehend due to the opaque nature of the melt and the mold and the viscosity of the liquid varies with time. The phase change, due to heat transfer also adds to the complexity of the problem. Since the mold and melts are opaque, motion of the melt cannot be visualized and analyzed with conventional measurement techniques. Therefore in order to study the various liquid patterns and the rate of cooling at different rotational speeds, it is necessary to make preliminary examinations about the nature of the liquid flow in a partially filled rotating cylinder at various rotational speeds. Cold modeling experiments have been carried out using liquids with different viscosities to study the fluid behavior. Influence of rotational speed of the mold, its optimization to form a liquid cylinder and regular cooling rates at different rotational speeds have been carried out. In this research work, an attempt is made to study the process of solidification and the effect of solidification structures on the mechanical properties of centrifugal castings. The three types of solidification processes have been carried out. One being the solidification of pure Tin and the others being the solidification of alloys such as eutectic Al-12wt%Si alloy and a hypereutectic Al-17wt%Si alloy they have a range of temperature to solidify. Tin metal is used to study the metallurgical behavior of pure metal, as it is having low melting temperature of 231oC, Al-12wt%Si alloy of melting temperature 577oC and Al-17wt%Si alloy of melting temperature 577oC to 620oC are used to analyze the metallurgical behavior of the alloys and also to study the particle segregation in the cylinder across the thickness of the casting. Eutectic as we know is a reversible isothermal reaction of a liquid metal which forms two different solid phases in a binary system upon cooling, i.e., L= α +β. This is an invariant reaction in which liquid phase transforms to two solid phases. The rate of solidification of any melt during centrifugal castings is of great importance because of its role in determining the microstructure and mechanical properties. The rate of solidification of pure metal in centrifugal casting is measured based on the grain size and for the Al-Si alloys it is measured based on the Secondary Dendrite Arm Spacing (SDAS). In this work properties like grain size, solidification rate, hardness, and specific wear rate are determined. It is found that the regions where rapid solidification occurs, there fine equi-axed grains are observed and coarse grains are observed at regions where slow solidification takes place. In casting experiments the cooling curves were drawn for the gravity castings which were made initially by monitoring the cooling rate. The microstructures were analyzed using image analyzer. Grain sizes have been measured and a graph is plotted for rate of solidification verses grain size. Using this data the rates of solidification of centrifugal castings are inferred, based on the grain size of the castings. The effect of mold wall thickness on rate of solidification is evaluated by making the castings using molds with varying wall thickness. Experiments have been conducted to study the effect of mold preheating on rate of solidification. As the mold temperature increases the temperature difference between the die and the molten metal decreases and hencerate of solidification decreases. Fast solidification rate leads to the fine grain formation leading to an increase in hardness and decrease in specific wear rate. For all the cases the variation in hardness along the radial direction is determined. Specific wear rate have been determined at the inner and outer surfaces of the cylindrical castings. For the Al-12wt%Si centrifugal casting by evaluating SDAS the solidification rates have been calculated. Variation in hardness and specific wear rate were also studied. Fine grains were observed at the outer surface of the cylindrical tin casting which is due to the chilling effect and hence the hardness was found to be higher compared to the hardness at the inner surface. It is also found that hardness is gradually decreasing towards the inner radius of the casting. But in case of Al-12wt%Si at the outer surface the hardness is higher due to chilling effect with the cold mold wall. At the inner surface hardness is higher due to the segregation of Si particles at the inner surface, because of its lower density with the matrix and also due to the centrifugal effect on the Si particles at higher speeds of rotation of the mold. Similar results have been obtained in case of Al-17wt %Si castings with slightly higher hardness at the inner surface of the casting.