NUST Institutions Library Catalogue Search for 'an:124804'

Development of Neural Augmented Ant Colony Optimization (NaACO) Technique for Scheduling Problems /

By UMER, MUHAMMAD. . 182p. , This dissertation focuses on the development of an intelligent prone methodology for efficient and effective handling of scheduling problems. In industrial concerns the issues/problems related to resource scheduling arise from abrupt and sudden demand and want patterns due to clustered and unbalanced supply of resources and assets. A novel technique in this respect has been developed and implemented on cases from industry. This technique takes into stride the efficiency demonstrated by various PSO (Particle Swarm Optimization) inspired techniques, combined with the intelligent prone ANNs (Artificial Neural Networks). Novelty and uniqueness is demonstrated through amalgamation of these approaches to introduce a term: NaACO (Neural Augmented ACO). This formulation is done under the umbrella of introduction of yet another unique approach i.e i-ACO (Intelligent ACO) theme through Neu(Tau) or Neuτ.This thesis also focuses on how ACO takes into account and absorbs the neural aspect of supervised and unsupervised learning. The intention of this research is to come up with a unique, customized and yet efficient way to handle the problems of the industry under given limitations and constraints. A complete model for this approach is built and for the application of the model a high technology aviation maintenance industry (case study I) is selected along with a medium technology manufacturing setup (case study II). The usage of ACO meta-heuristic is taken as an ideal reference point with which every problem set can be converged towards a best fit solution. Subsequently ANN is used to come up with a combitorial dialog box to prompt for the inputs and evaluate the outputs of the given problem. The thesis contributes to current research by introducing NaACO, i-ACO through intelligent scheduling (hence introducing neuτ); which proposes many solutions of the existing problems. The discussion and conclusions part at the end summarizes the research and the future areas of research are also elaborated to assist and appreciate future researchers who are interested to endeavor in this field and related applications. 30cm.

Place Hold on Development of Neural Augmented Ant Colony Optimization (NaACO) Technique for Scheduling Problems /

Analysis of Specific Cutting Energy Consumption during Machining of Al 6061-T6 alloy, using the Energy Map Approach /

By Warsi, Salman Sagheer . . 199p. , There is an increased emphasis on energy efficiency of manufacturing processes owing to their negative impact on environment. Machining is one of the most widely used process in the manufacturing industry and accounts for more than 15% value in the globally manufactured products. Electrical energy consumption is considered as the major source of environmental and economic impact of machining processes. A number of studies can be found in literature that model and optimize energy consumption in machining processes. However, most of these studies employ power and energy as response variables that makes them machine tool specific. Therefore a generalized machine tool independent approach needs to be developed for energy consumption analysis in machining processes. This research addresses this problem by utilizing specific cutting energy as a response variable. Specific cutting energy takes into account cutting power and material removal rate and is independent of machine tool. A novel specific cutting energy map approach has been presented in this research. Al 6061-T6 alloy has been used as the workpiece material owing to its extensive application in automotive, aerospace and other high-tech products. The developed energy maps can represent specific cutting energy consumption in the form of different regions (very high, high, moderate, low and very low) against varying cutting condition. The energy map approach has been applied in conventional, transitional and high speed machining ranges. The formation of specific cutting energy regions has been investigated and it has been shown that these regions are strongly related with mechanics of cutting process in terms of: shear angle, chip ratio, chip formation, and contact length. It has been shown that energy saving up to 52% in machining of Al 6061 alloy can be achieved by selecting appropriate cutting parameters from the developed energy maps. The undeformed chip thickness was observed to be the most influential machining parameter affecting specific cutting energy consumption. The developed energy maps also revealed the presence of an avoidance zone associated with high cutting speeds and low undeformed chip thickness. Built-up edge was observed to be responsible for formation of avoidance zone. 30cm.

Place Hold on Analysis of Specific Cutting Energy Consumption during Machining of Al 6061-T6 alloy, using the Energy Map Approach /

Finite Element Simulation and Experimental Investigation of Conventional and High Speed Machining of Al 6061-T6 Alloy /

By Akram , Sohail . . 152p. , Aluminium based alloys are important industrially, owing to their high machinability, corrosion resistance, and strength to weight ratio. These properties make them highly suitable to be used in automotive, aerospace and food processing industries. Due to its high industrial importance, minimal tool wear and superior machining characteristics, Aluminium 6061-T6 alloy has been selected as the workpiece in many research works. Many research studies have been conducted in the past for the experimental and numerical investigation of cutting forces, temperatures, residual stresses and tool wear etc. during machining of Al 6061-T6 alloy. A close agreement was found between experimental and simulated results, however, the available FE models for aluminium based alloys have generally been limited to low and medium cutting speed ranges (i.e. below 1600 m/min). It was observed that the experimental cutting forces were dropped suddenly during High Speed Machining (HSM) condition of Al 6061-T6 alloy. This sudden drop in the experimental cutting forces due to adiabatic heating and reduced coefficient of friction at HSM, was not captured accurately by existing models. An effective predictive model which can numerically investigate the effects on Al 6061-T6 alloy in the high speed machining regime (i.e. above 1600 m/min – 2000 m/min) at the feed rates (f) of 0.1-0.4 mm/rev has previously not been reported in the literature. The current research therefore aimed towards the development and testing of an effective FE model that is capable of simulating the machining of Al 6061-T6 alloy at conventional as well as high speed regime. In the current research work, extensive experimentation and numerical investigations were carried out covering low, medium and high speed/shear rate machining regimes using a dynamic coefficient of friction and thermal softening effect at HSM condition. This approach considerably improved the predicted cutting forces obtained through the existing sets of Johnson-Cook (J-C) material constants. The maximum error of (Fc) were reduced to 19.1% and 23.7% at higher cutting conditions for both existing data sets of material constants, compared to earlier predictions of 36% and 41%, respectively (at higher coefficient of friction and without considering adiabatic heating effect). The current research work adopted a new method for measuring cutting forces using a power meter through specific cutting energy approach, by carrying out extensive experimentation and literature validation, which is more economical than commercially available force dynamometers. Besides, for the first time, low, medium and high speed ranges during machining of Al 6061-T6 alloy were defined accurately during the current research work. Finally, a suitable set of J-C material constants were selected through inverse methodology which was found to be as accurate as existing sets of J-C material constants in LSM and MSM regimes but was also found to be more accurate in the HSM range. Therefore, the set of J-C material constants selected in this research work can be used in a consolidated model for the entire cutting range with accuracy greater than the sets of J-C material constants available prior to this research. 30cm.

Place Hold on Finite Element Simulation and Experimental Investigation of Conventional and High Speed Machining of Al 6061-T6 Alloy /

Fixed-Value MBLL based Cognitive Hemodynamic response assessment using P-fNIRS system: Applications to Deep Learning Brain Machine Interface (BMI) /

By Asgher,Umer . . 172p. , Humans in the modern systems not only interact with other humans but also have to interact with intelligent machines, robots in form of cyber physical systems to collaborate in order to carry out different tasks in real working environment. The modern Industrial system comprises of humans, machines, and cyber systems with a collective aim of optimized industrial manufacturing objectives, human factors, and ergonomics goals. Different macrohuman factors are considered while designing and formulating human work safety of such systems and one of the important neuroergonomic factors in is the Cognitive and Mental Workload (C-MWL). The mental workload (MWL) in the human’s brain is measured with difference non-invasive neuroimaging techniques. Most of the cognitive load measuring methods either require massive system protocols like fMRI (functional magnetic resonance imagining), positron-emission tomography (PET) or strict human anatomical movements restrictions like electroencephalogram (EEG) and magnetoencephalography (MEG). To address these limitations, fNIRS (functional Near infrared Spectroscopy) is used in this research to measure the hemodynamic changes in the human brain’s tissues as a measure of the brain activity. The brain’s hemodynamic signals are measured using a light weight portable fNIRS system (P-fNIRSSyst) that is designed to measure relative change in concentration of chromophores (oxy and deoxy hemoglobin) in brain tissues. In this study a novel variant of MBLL (Modified Beer-lambert Law) is designed by keeping the previous intensity value as a reference by taking the average from initial four seconds activity stimuli in optical density. The four second stimuli average in novel and important in calculation the changes in concentration of chromophores. This novel variant of MBLL is Fixed Value - Modified Beer-lambert Law (FV-MBLL). In this research, MWL is measured and classified in different real time working environments. The two-state cognitive load is measured with fNIRS system and classified using FV-MBLL using machine learning techniques like k-nearest neighbors (k-NN), support vector machines (SVM), and artificial neural networks (ANN). The classification accuracies of FV-MBLL are better than MBLL. The research further explores the classification capabilities of deep neural networks (DNN) such as convolutional neural network s (CNN) and Long short-term memory (LSTM) for the first time in assessment and classification of four- iv state MWL. The classification accuracies of LSTM outperform not only ML algorithms (SVM, KNN and ANN) but CNN as well in classification of multi-state MWL. The research experimental validation is performed using the accuracies with MWL that are further utilized in neurorehabilitation as neurofeedback to operate bionic systems using Brain Machine Interface (BMI). 30cm.

Place Hold on Fixed-Value MBLL based Cognitive Hemodynamic response assessment using P-fNIRS system: Applications to Deep Learning Brain Machine Interface (BMI) /

Energy Consumption and Tool Wear Analysis in Machining of Titanium Alloys (Ti6Al4V /

By Younas, Muhammad . . 177p. , Mechanical machining is one of the commonly employed techniques in manufacturing industries, given several other production processes. Due to their high hardness and specific strength at elevated temperatures, machining of titanium alloys is considered very difficult. Considering the machinability challenges of these alloys, tool wear and energy consumption during machining remain the main concern for achieving sustainable machining goals. Since the tool wear is linked to the product quality and cost of machining, therefore, a comprehensive wear map approach based on experimental cutting test is very useful for monitoring the tool life. Whereas energy consumption in a machining process is associated with the machine tool efficiency, cost of energy and carbon footprints, the evaluation of energy consumption using energy maps is therefore very helpful in improving machining performances. Thus, improving the tool life and minimizing energy consumption are the prime contributors in achieving economic and energy-efficient benefits of production. The research presented here first studied the tool wear progression in turning of titanium alloy (Ti6Al4V) and then the effect of progressive tool wear on specific cutting energy was further analyzed for the development of the energy map. Tool Wear and Specific Cutting Energy maps were developed for turning of Ti6Al4V alloy by performing a series of unified cutting tests. The wear map developed plots the wear rate on a feed Vs. cutting speed grid and have identified regions of low, moderate and high tool wear rates. Interestingly, a high wear zone (avoidance region) at the interface of low and moderate tool wear appeared on the wear map. Analogous to the wear map, regions of low, moderate and high energy consumption were also identified on the energy map. The two maps developed thus corresponds to the cutting conditions employed in turning operation highlighting high energy and wear regions that should be avoided during the cutting process. Although wear maps have been presented for a variety of materials including Ti6Al4V alloys, this research work presents a wear map together with energy map for turning Ti6Al4V alloy. The energy map plots the Specific Cutting Energy (SCE) utilized at the tooltip against the cutting condition used in the turning process. The energy map methodology was used for the selection of optimal cutting condition that will minimize the energy consumption of the machine tool. The study of the tool chip contact length and the chip formation analysis is a way to understand the interactions and mechanics of a machining process. The analysis of the tool’s flank surface revealed that the chemical interaction between the tool and workpiece is the main cause for high tool wear and energy consumption as titanium alloys are well known for its severe ix reactiveness at higher cutting temperatures. Since machining of titanium alloys is challenging because of the inherent properties of the material, therefore, this research was focused on the study of energy consumption and tool wear analysis to achieve economic and sustainable goals of production engineering. The energy and wear maps thus developed are also very useful on the shop floor and provide for the choice of cutting conditions to produce parts from Ti6Al4V alloys, together with less damage to cutting tools and efficient use of machine tools. 30cm.

Place Hold on Energy Consumption and Tool Wear Analysis in Machining of Titanium Alloys (Ti6Al4V /

Improvement in Magnetic Properties of Samarium-Cobalt (1:5) Alloy through Controlled Material Processing /

By Akhtar, Saleem. . 195p. , Permanent magnets are defined as solid materials that provide sufficiently high magnetic flux and offer resistance to demagnetizing fields. High magnetic flux can be controlled by changing the chemical composition of the permanent magnetic material but the demagnetizing field resistance called coercivity depends upon the shape or crystal anisotropies and the process in which microscopic regions of the material are further subdivided. Permanent magnetic materials include a variety of ceramics, intermetallics and alloys. Samarium-cobalt (SmCo) magnets are rare earth magnets and are known for their high coercivity and Curie temperature. In this class of magnets, SmCo5 has a potential to demonstrate highest coercivity due to its high magneto-crystalline anisotropy. However; only 4% of the theoretical coercivity values are achieved so far. One method of improving the coercivity is through alloying while the other is through process control. The latter technique is used to improve the microstructure of the magnet. In this research the improvement of coercivity of SmCo5 is focused through process control. The microstructure of SmCo5 has been controlled through processing at the stages of manufacturing i.e., casting and ball milling. In the first stage, the microstructure was controlled using conformal cooling channels in the mold i.e., through controlled solidification. The samples from this process were compared with the spin casting technique. It was observed that the formation of Sm2Co7 and Sm5CO19 are responsible for lowering the coercivity of the magnetic material. Therefore, the solidification temperature was controlled to achieve better microstructure. The results show that the casting produced at the lower temperatures had nano-sized peritectic lamellar structure. These nano structures are belived to improve the coercivity of SmCo5 to 32.9 kOe, which is one of the highest reported value. In the second part of this thesis, the focus was on the optimization of the ball milling parameters i.e., the process by which fine powder is produced. Ball-milling affects the shape, size distribution and mean particle size and consequently the final magnetic properties. The Taguchi L9 experimentation was designed to determine the effect of different parameters on the magnetic properties of the final product. It was noted that the ball milling speed, ball to powder ratio and time are the most significant process parameters which affects the coercivity of the final magnet. Best combination of these parameters was time and ball to powder ratio. ix In this work novel mold design was introduced which can provide the casting with fine microstructure. The coercivity values upto 32.9 kOe were achieved with the same mold design. Further, the optimization of ball milling parameters through Taguchi was done for SmCo5. Novel nano-structures were observed in SmCo5 before and after sintering process. 30cm..

Place Hold on Improvement in Magnetic Properties of Samarium-Cobalt (1:5) Alloy through Controlled Material Processing /

NUMERICAL & EXPERIMENTAL INVESTIGATION OF EFFECTS OF PROCESS PARAMETERS ON ELECTROMAGNETIC FORMING OF METALS /

By Khan, Zarak . . 205p. , Electromagnetic forming is a highspeed forming process in which a metallic sheet is driven by the impulsive magnetic force generated by transient induced current. In this type of forming there is no mechanical contact between the workpiece and tool. The deforming force is attributed to the Lorentz force produced due to a transient current passing through the coil. This technique can be used to achieve a wide range of operations such as compression and expansion of metallic tubes using helical coils, flat sheet forming into three-dimensional shapes using flat spiral coils. The technique can also be used for other operations like cutting, welding, hemming, joining, and crimping. The technique is used to deform metals with low electrical conductivity using aluminium as a driver. Due to growth in industrial applications, the demand for better-simulating tools and parametric analysis of process parameters to improve the electromagnetic forming process is also increasing. The present research aims to provide detailed parametric analysis and an efficient Finite Element (FE) model for the analysis of the electromagnetic forming process. A 2-D symmetric FE model has been developed and compared with the experimental data. The model consists of three main modules which are fully coupled namely electrical circuit, magnetic field and solid mechanics. In this work, particular attention is assigned to the study of the most relevant process parameters, focusing on their significance, effects and mutual interaction. To evaluate the performance of the proposed approach, numerical results were compared with experimental results and those proposed in the literature, to assess the robustness and accuracy of the proposed model. The obtained results show a good correlation between numerical and experimental results. The effect of sheet deformation on changing magnetic flux and system inductance was considered in the numerical model. A good agreement with experimental results was observed. The effect of varying parameters on the deformation, change in sheet thickness and the velocities of equidistant points were numerically calculated. The maximum error observed in numerical and experimental deformation was 4.9%. A Taguchi L9 array is used for the Design of Experiments (DoE). Three parameters such as Input voltage, sheet thickness, coil parameter. These sets of experiments were performed on AA6061-T6 to check the deformation and thickness variation response by changing process parameters. The most significant parameter during sheet deformation was estimated using ANOVA technique. It was observed that the effect of coil turns was negligible as compared ix to the input voltage and sheet thickness on sheet deformation. The contribution ratio of input voltage in sheet deformation was 46.21% while that of sheet thickness was 45.13%. The same technique was used to analyse the effects of process parameters (input voltage, driver sheet thickness, driven sheet thickness) on the deformation of non-magnetic stainless-steel sheets (SS304) using AA6061-T6 sheets as a driver. The results revealed that all three process parameters (i.e. input voltage, driver sheet thickness, driven sheet thickness) are significant. The contribution ratio of input voltage in sheet deformation was 23.98%, the contribution ratio of driver sheet thickness was 19.07% while that of driven sheet thickness was 51.6%. A numerical investigation of driven sheet dynamics and deformation was carried out. A good agreement with experimental results was observed with a maximum error in deformation of less than 5%. The proposed method is very useful to industries and provides a better understanding of the important parameters using simulation tools without wasting time and energy on experimental trials. 30cm..

Place Hold on NUMERICAL & EXPERIMENTAL INVESTIGATION OF EFFECTS OF PROCESS PARAMETERS ON ELECTROMAGNETIC FORMING OF METALS /

Optimization of Makespan for Flexible Job Shop Scheduling Problems using Genetic Algorithms /

By Amjad, Muhammad Kamal. . 150p. , Manufacturing scheduling is one of the most researched areas since its optimality plays an important role in the operation of the shop floor. Manufacturing has a vital contribution in the overall economy of a country as it generates and attracts commercial activities. The whole framework of business has changed in view of the fluctuating global customer demands and fierce opposition from technologically advanced competitors. There is always a pressure on the manufacturer to produce the designed products in the shortest possible time to capture the market. To the challenge of changing product requirements and market demands, flexible manufacturing system is the answer. Flexible job shop is employed to produce a medium variety of products in a medium volume category. In contrast to the conventional job shop, it offers flexibility in performing operations on different machines; hence providing space for the manufacturing planner / scheduler for arranging parts as per corporate requirements. When seen in the context of optimal operation, this setting while offering such great advantage, also poses the scheduler with the decision regarding assignment of operations to available machines in addition to sequencing of operations. In this way, the complexity of the problem grows exponentially even in the small settings of the shop. The flexible job shop scheduling is a NP-hard combinatorial optimization problem with regards to complexity and its exact solution requires many lifetimes to reach. Consequently, techniques built around the concepts of artificial intelligence have been popularly used to solve the problem. Genetic Algorithm (GA) is one of the most attempted and widespread technique from this domain. GA can produce good results of the scheduling problems, however when stuck in the local minima, the algorithm normally fails to escape, and solution quality is badly affected. In this research work, problem is formulated mathematically and insights to a selected benchmark is provided. Problem complexity is then evaluated in a quantitative way through estimation of search space of the selected datasets and an understanding to the actual area of search is developed. Priority rules are then integrated with the GA (GA-PR) to solve the FJSSP. In this regard, competitive modification in the rule has been proposed in addition to the integration scheme. The algorithm is also equipped with adaptive operators which also contribute to its performance. In addition to this a standalone pure GA (GA-IDT) is also proposed to efficiently solve the target problem. An iterative diversification technique is embedded into the proposed algorithm which proficiently manages the intensification and diversification of the population. The efficacy of both algorithms is tested against standard benchmark problems and it is concluded that proposed techniques are competitive with other concepts in literature. 30cm..

Place Hold on Optimization of Makespan for Flexible Job Shop Scheduling Problems using Genetic Algorithms /

Investigation into the Machinability of Titanium Alloys under Cryogenic Conditions /

By Khan, Muhammad Ali . . 214p. , Manufacturing has been an important activity throughout the history of human civilization. Manufacturing industries use raw materials and labor to convert natural resources into finished products through the use of technology. The manufacturing sector accounts for around 45% of global energy consumption. Manufacturing processes should therefore be productive as well as sustainable. Machining is a subtractive manufacturing process that removes excess material through the use of a cutting tool in order to give the bulk engineering material a functional geometry. It constitutes about 15% of all manufacturing processes. Machining processes are simple, efficient, versatile and economic for bulk production. These processes represent a major chunk of activities run to design and manufacture parts in various industries. A number of metals, alloys and ceramics are processed through machining. Titanium alloys are generally the preferred choice when it comes to applications where corrosion resistance, high strength to weight ratio and good fatigue properties are required. In addition, titanium based alloys also exhibit biocompatibility. These alloys are extensively used in medical, marine and aerospace industries. On the other hand, their low thermal conductivity and high temperature strength reduce tool life and increases energy consumption during the metal cutting processes. Several research studies have focused on productivity, sustainability and quality aspects of machining of titanium alloys as these are important aspects of manufacturing research. Nevertheless, systematic parametric analysis for machining titanium alloys under various cooling conditions, especially cryogenic conditions presents a research gap. Also, since the available process maps were developed under dry conditions, there is a need for development of tool wear and energy maps, being vital output responses, under cryogenic conditions. This research focuses on investigating the machinability of Ti-6Al-4V alloy over a range of machining parameters under varying cutting environments. Dry, wet and cryogenic conditions were selected as cutting environments for comparative analysis. Different machining input parameters were taken into consideration for analysis of key responses including tool wear, specific cutting energy, surface roughness and material removal rate. Process maps were developed by plotting tool wear rate and specific cutting energy against cutting speed and feed. These maps can be effectively used on the shop floor to select specific machining parameters for ix desired output response. Initially tool wear progression was analyzed under dry and cryogenic conditions which formed the basis for further research. Comparative tool wear analysis was conducted at low, moderate and high tool wear regions. It was observed that cryogenic machining improved tool life owing to its cooling capacity. Next, investigation into the machinability of Ti-6Al-4V was conducted by statistical analysis and multi objective optimization under varying machining conditions. Feed rate, cutting speed and depth of cut were taken as the input parameters under dry, wet and cryogenic conditions. Statistical analysis results identified cutting speed as the key input parameter for tool wear rate and specific cutting energy consumption in terms of contribution ratio. On the other hand, feed had the highest contribution ratio for surface roughness. Multi objective optimization was carried out to optimize the machining output. Each machining run was ranked using grey relational analysis. Analysis of regression model of multi objective function identified feed as the most effective input parameter followed by machining environment. Process maps, developed using cryogenic media, demarcated wear and energy charts into regions of low, moderate and high tool wear and energy zones. A high wear zone found amidst lower zone region was marked as avoidance zone. Tool wear map regions of low, moderate, high and avoidance zone were analyzed by plotting tool chip contact length. As compared with the wear map for turning of titanium alloys under dry conditions, the avoidance zone for this wear map shifted towards high feed region. EDS elemental analysis was also carried out to determine and analyze the wear mechanisms during the machining of Ti-6Al-4V. These maps were also characterized using chip morphology by chip compression ratio and shear angle. These maps can prove to be highly useful in making the manufacturing system productive and sustainable at the same time. 30cm..

Place Hold on Investigation into the Machinability of Titanium Alloys under Cryogenic Conditions /

Development and Analysis of Advanced Functional Alloys /

By Haider, Ali /. . 253p. , This work comprises of research on development and analysis of two selected alloys based on economic viewpoint, namely; FeCrCo magnetic alloy and NiCrMo dental casting alloy. The research was initiated for compliance to the United Nations guidelines for the Global Goals. The Sustainable Development Goals (SDGs) are the goals of United Nations for peace and prosperity for the people and the planet. The SDGs are an urgent call for action to end poverty and improve health, economy and education. In order to comply with the SDGs, this project was aimed to attend the three global goals including; i) Goal-3 for Good Health and Well Being, ii) Goal-7 for Affordable and Clean Energy and iii) Goal-9 for Industry, Innovation and Infrastructure. Accordingly this research was carried out on low cost FeCrCo magnetic alloy and NiCrMo dental casting alloy. FeCrCo alloy is the most economical alloy for permanent magnet making as it uses low cost elements; however, magnetic energy product can be produced that is at par with that of Alnico magnets. Similarly, NiCrMo alloy is also a very economical dental casting alloy that possess properties equivalent to that of gold alloys, used for the purpose of dental restorations. Both the alloys are technically very suitable for poor and developing nations for providing economical solutions. Economical processing and production of FeCrCo magnets can contribute to the efficient high speed motors and for affordable and clean energy devices. Also this research conducted on NiCrMo dental casting alloy is a remarkable contribution towards affordable dental health care. FeCrCo is a typical deformable magnetic alloy. In this research, the FeCrCo alloy with low cobalt content (12 wt. %) was developed, processed and analyzed. Effect of minor alloying with silicon was investigated, where enhancement of remanence ratio and improvement in squareness of the MH curve was noted with the double isothermal thermomagnetic processing. Taguchi design approach was utilized for properties optimization. Signal-to-noise ratio mean plots demonstrated that best magnetic characteristics, maximum energy product (BHmax) up to 3.89 MGOe, achieved in samples that were forged, thermomagnetically processed and thermally aged for 24 hour treatment cycle. NiCrMo alloy being an economical alloy is popular for dental restorations. Currently NiCrMo alloys are in use by dental labs that contain beryllium in its composition, which is carcinogenic in nature. This research work was conducted on manufacturing and development of the NiCrMo dental casting alloy with minor additions of titanium, cerium and boron to enhance strength, corrosion and tribological characteristics and to decrease the melting temperature for ease of fabrication. Novelty is that the addition of 0.2 percent Boron with 0.4 percent cerium in the base NiCrMo dental casting alloy is found with outstanding combination of characteristics, well suited for dental restorations. The alloy developed has economic significance, especially, for poor and developing nations as the NiCrMo alloy can be used as replacement for gold based costly alloys. The work done could also help in avoiding Be-containing NiCrMo alloys and is a contribution to the bulk material sciences. 30cm..

Place Hold on Development and Analysis of Advanced Functional Alloys /

Investigating the High-Speed Micro – Machinability of Aerospace Alloys /

By Baig, Amjad . . 206p. , Micro technologies including Micro-Machining have become essential part of the various industries of modern era. Micro-machining is contributing to almost all fields of industries like aerospace, automobiles, telecommunication, electronics, and medical sectors etc. Therefore, 3D products in the industry require quality product and dimensional accuracy even at micron level. Micro-milling, the most versatile micro-machining technique, has gained importance in mass production of 3D components. Micro mechanical tools have great potential for economical manufacturing of miniatured products from variety of materials, in micro-milling operations. However, the previous research work shows some critical issues in direct application knowledge of macro machining domain into micro domain with help of simple analysis of parts dimensions. Thus, research work focuses on areas which require scientific knowledge to be developed for further implementation at micro scale level to improve the quality of final product. Mechanical micro-milling of aerospace alloys remained focus of many researchers in past because of having excellent mechanical properties, at extreme temperatures, that are suitable for different sectors like aviation, automotive, nuclear, marine, and biomedical applications. These are also considered a better option for applications where stresses need to be minimised. Inconel alloy (Nickel-chromium based) and Monel alloy (Nickel-copper based) being part of aerospace alloy, possesses greater strength and excellent corrosion resistance, work hardening properties at elevated temperature. In aerospace sector, parts like discs, some critical jet engine parts are also being manufactured with these alloys. Nevertheless, Nickle alloys are hard to machine materials and have inherited poor machinability because of low thermal conductivity. Low thermal conductivity results in significant increase of temperature at the cutting zone which results in decreased life of cutting tool. Available research knowledge of vital process parameters (feed per tooth, depth of cut, cutting speed, etc.) in relation to micro-milling of Monel and Inconel alloys at high-speed micro-machining (HSM) under various cooling environments and with multiple micro tool coatings present a research gap. There is need to cover this gap by analysing effects of multiple cutting parameters with wide range on responses at high-speed micro-machining of these alloys. This research focuses on investigation of high-speed micro machinability of aerospace alloys including Inconel 600, Monel 400 under multiple cooling environments and various cutting x conditions. Machining related key input parameters like cutting speed (m/min), feed per tooth (µm/tooth), depth of cut (µm), various micro tool coating (TiAlN, TiSiN and nACo) and multiple cooling conditions (Cryogenic, wet and dry) were taken into considerations for analysis and their effect on responses like tool wear, surface roughness, and burr formations. To have a thorough insight into micro machinability of aerospace alloys, Feed per tooth, was selected above and below the cutting-edge radius of the micro tools. Due consideration was also given to burr formation at up milling side and down milling side. All experiments were categorized into three sets, where first set of experiments were carried out with key process parameters under various cooling conditions (Cryogenic, wet and dry). Second set of experiment was conducted with input parameters using multiple micro tool coatings (TiAlN, TiSiN, nACo) in addition to un-coated micro tool. Third set included validation experiments of all categories. Investigation, into the micro machinability of Inconel and Monel alloys, was carried out through statistical analysis and multi objective optimization (MOO) with various cooling environments and multiple cutting conditions. As process parameters and response parameters are independent and different in nature therefore multi objective optimization was essentially required to optimize the machining output. Grey Rational Analysis (GRA) ranked each experiment. Regression model analysis of multi objective function, identified optimum process parameters in both categories. Outcome of this research work provides in-depth and significant knowledge on utility and importance of making manufacturing system more productive with quality and accuracy required for 3D parts at micro-machining level. Results show that proper selection of tool coatings and cooling environment produce significant improvements in performance compared to conventional tools and cooling environments, in field of micromachining. As a result of ANOVA, ‘Cooling condition’ figured out the most significant factor with contribution ratio (29%) towards surface roughness followed by cutting speed with contribution ratio (26%). It was also influential factor for tool wear with contribution ratio 26%. Feed per tooth figured out as most significant factor for their effect on burr formation in both cases i.e., up, and down milling case for Inconel 600 alloy with contribution ratios, Burr width - down milling case (66%), Burr height- down milling case (44%), Burr width- up milling case (35%). xi Feed per tooth was the most significant factor for its effects on surface roughness including burr formation in both modes i.e., up and down milling side, in micro-milling of Monel 400 alloy using multiple tool coatings, with contribution ratios, Surface roughness (28%), Top Burr width (up and down milling side) 56%, 57%, Top Burr height (up and down milling side) 24%, 28%, respectively. Depth of cut is the most significant factor for tool wear with contribution ratio 34%. nACo coated tool showed least tool wear in micro-milling of Monel 400 alloy whereas uncoated tool showed worst tool wear. Cutting condition, with TiAlN coated tool, has a positive intercept gain of 4%, 8% and 1.03% on uncoated micro tool, TiSiN micro coated tool and nACo micro coated tool conditions, respectively 30cm..

Place Hold on Investigating the High-Speed Micro – Machinability of Aerospace Alloys /

Experimental and Numerical Investigations on Formability Characterization in Single Point Incremental Forming of Steel Tailor Welded Blanks /

By ATTIQUE, USMAN . . 201p. , Manufacturing industries are seeking for new high strength, lightweight materials along such techniques and designs to optimally utilize these materials to produce quality and reliability in their products while simultaneously reducing cost and weight of the products. Tailor Welded Blanks (TWBs) employ such technique which exploits the advantages of localized strength and less material consumption resulting into lesser part weight. TWBs are largely used in Body-inWhite (BIW) of all modern automobiles. Research was conducted on TWBs produced successfully by manual TIG welding technique. Incremental Sheet Forming (ISF) is in practice with its several variants using TWBs. Material selected for the study included deep drawing quality (DDQ) steel (DC06) and stainless steel (SS) (AISI 201). Because of huge difference in both strength and hardness values of DDQ steel and SS, low formability was achieved in case of strength differential. Whereas formability achieved in the cases of same thickness and thickness differential were high since strength and hardness values were not varied much. Process parameters also affect formability to a fairly large extent. In case of same thickness, highest formability was achieved at maximum feed rate but minimum speed. In case of thickness differential, highest formability was achieved at minimum values of feed rate, speed and step depth. In case of strength differential, highest formability was achieved at minimum values of speed and step depth. Percentage thinning was used to assess formability achieved. Final thicknesses achieved during forming were verified by Cosine law. TWBs is a complex phenomenon, as compared to finite element modeling of monolithic sheets, which involves modeling of different zones generated due to the heat effect. Single Point Incremental Forming (SPIF) was used as a forming technique for TWBs produced by manual Tungsten Inert Gas (TIG) welding and experimental outcomes were compared with simulation results. FE software Abaqus® (Dynamic Explicit Solver) was used for the analysis with variable wall angle truncated pyramid as test geometry and Isotropic plasticity model as material model. Thickness profiles and state of stress and strain in all the cases were analyzed. A decrease in thickness was observed at the corners in all the cases, whereas decrease was more prominent in case of same thickness and strength differential. The symmetry of pattern on both sides with minimum and maximum values of stress towards the thinner side was observed in case of thickness differential. Variation in stress was more prominent towards the side of high-strength material along maximum value in case of strength differential. Equivalent plastic strain observed was more xi linear and higher towards the sides of thicker sheet and material having less strength in case of thickness differential and strength differential, respectively. Research investigations may be applied in similar fashion for precise study of formability characteristics of various kinds of TWBs being used in multiple industries including automotive, vessel, medical, etc. 30cm..

Place Hold on Experimental and Numerical Investigations on Formability Characterization in Single Point Incremental Forming of Steel Tailor Welded Blanks /