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Dumene, Richard Lawrence. „Manufacture and Characterization of Additively Manufactured Ceramic Electromagnetic Structures“. Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83484.
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Additive Manufacturing (AM, also known as 3D printing) can produce novel three-dimensional structures using low-loss dielectric materials. This enables the construction of dielectrics with complex shapes that enable innovative microwave applications such as resonators, filters, and metamaterial lenses. This thesis addresses the production and characterization of cellular structures of various designed densities created with a low loss ceramic material, alumina (aluminum oxide), via vat photopolymerization. The permittivity of these printed structures is variable over roughly an octave, with a range of relative permittivites from 1.78 to 3.60, controlled via part geometry. Two additional materials, ferrite and nickel, have been explored for inclusion within these dielectric structures to enable the production of multi-material electromagnetic structures with conductive, magnetic, and dielectric elements.Master of Science
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Campos, Reales Castellanos Jose Eduardo. „Novel zeolite manufacture“. Thesis, University of Birmingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422716.
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Normand, Marie-Astrid. „La manufacture d'orgues Krischer“. Thesis, Paris 4, 2011. http://www.theses.fr/2011PA040070.
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Au cours du XIXe siècle, la facture d'orgue française s'épanouit. Des petites manufactures, comme celle des Krischer à Rouen, prospèrent malgré l'influence des plus grandes. Facteur d'orgue le plus réputé, Aristide Cavaillé-Coll construit presque tous les grands instruments français de l'époque. La facture d'orgues fait partie des professions où le savoir se transmet de génération en génération : ce fut le cas des facteurs Isnard ou Cavaillé-Coll. Il en sera même pour la famille Krischer : depuis Henry-Jean Krischer jusqu'à ses arrières petits-enfants, on peut relever au moins sept personnes qui ont pratiqué ce métier. Fils d'une famille originaire de Nideggen, près d'Aix-la-Chapelle, Jean-Hubert Krischer est facteur d'orgue à Paris, père de deux facteurs d'orgues : Marie-Joseph, et Hubert François. Ce dernier a notamment travaillé dans les ateliers parisiens des manufactures Merklin, Cavaillé-Coll et Martin, avant de monter sa propre fabrique en 1873 à Rouen, où ses descendants (Georges, Henry, Ernest et Paul) apprendront le métier. Dans cette thèse, plusieurs points seront abordés pour définir les esthétiques des instruments des Krischer : après avoir présenté toute la famille de ces facteurs d'orgues, nous nous intéresserons à l'épanouissement de cette manufacture d'orgues en France, en étudiant ses activités depuis 1860 jusqu'environ 1934. Nous décrirons aussi les instruments ayant eu des contacts avec ces facteurs, en notant les caractéristiques générales et les aspects typiques des instruments Krischer. Enfin, après la disparition des Krischer, nous poursuivrons l'étude de leurs orgues jusqu'à nos jours, en présentant comment ils survivent ou non dans l'HistoireIn the XIXth century, the French organ building expanded. Small manufactures, like the Krischer manufacture in Rouen, flourished in spite of the influence of larger manufactures. Regarded as the most renowned organ builder, Aristide Cavaillé-Coll built almost all the French large instruments at that time. The organ building belongs to those trades for which knowledge is transmitted from generation to generation, as it was the case for the Isnard or the Cavaillé-Coll builders. It was the same for the Krischer family: since Henry-Jean Krischer up to his great-grandchildren, we can pick out at least seven people who practised this trade. Jean-Hubert Krischer, who was the son of a family native to Nideggen near Aix-la-Chapelle, was an organ builder in Paris and was the father of two organ builders, Marie-Joseph, and Hubert François. The latter had more particularly worked in the Parisian workshops of the Merklin, Cavaillé-Coll and Martin manufactures, before creating his own manufacture in Rouen in 1873, where his descendants (Georges, Henry, Ernest and Paul) would learn the job. In this thesis, several points will be approached to define the aesthetics of the Krischer instruments: after having introduced the whole family of these organ builders, we will be interested in the expansion of this organ manufacture in France, by studying its activities from 1860 to approximately 1934. We will also describe all the instruments, by noting their characteristics of the Krischer instruments. Finally, after the disappearance of the Krischer manufacture, we will continue the study of the history of their organs until now, by showing how they did survive or not in History
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Tomlinson, Richard J. „Lens design for manufacture“. Thesis, Loughborough University, 2005. https://dspace.lboro.ac.uk/2134/14554.
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The manufacture of complete optical systems can be broken down into three distinct stages; the optical and mechanical design, the production of both optical and mechanical components and finally their assembly and test. The three stages must not be taken in isolation if the system is to fulfil its required optical performance at reasonable cost. This report looks first at the optical design phase. There are a number of different optical design computer packages on the market that optimise an optical system for optical performance. These packages can be used to generate the maximum manufacturing errors, or tolerances, which are permissible if the system is to meets its design requirement. There is obviously a close relationship between the manufacturing tolerances and the cost of the system, and an analysis of this relationship is presented in this report. There is also an attempt made to optimise the design of a simple optical system for cost along with optical performance. Once the design is complete the production phase begins and this report then examines the current techniques employed in the manufacture, and testing of optical components. There are numerous methods available to measure the surface form generated on optical elements ranging from simple test plates through to complex interferometers. The majority of these methods require the element to be removed from the manufacturing environment and are therefore not in-process techniques that would be the most desirable. The difficulties surrounding the measurement of aspheric surfaces are also discussed. Another common theme for the non-contact test techniques is the requirement to have a test or null plate which can either limit the range of surfaces the designer may chose from or increase the cost of the optical system as the test surface will first have to be manufactured. The development of the synthetic aperture interferometer is presented in this report. This technique provides a non-contact method of surface form measurement of aspheric surfaces without needing null or test plates. The final area to be addressed is the assembly and test stage. The current assembly methods are presented, with the most common industry standard method being to fully assemble the optical system prior to examining its performance. Also, a number of active alignment techniques are discussed including whether the alignment of the individual optical elements is checked, and if need be adjusted, during the assembly phase. In general these techniques rely upon the accuracy of manufacture of the mechanical components to facilitate the optical alignment of the system. Finally a computer aided optical alignment technique is presented which allows the optical alignment of the system to be brought within tolerance prior to the cementing in place of an outer casing. This method circumvents the need for very tight manufacturing tolerances on the mechanical components and also removes the otherwise labour intensive task of assembling and disassembling an optical system until the required level of performance is achieved.
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Gerber, Guillaume. „Designing for rapid manufacture“. Thesis, [Bloemfontein?] : Central University of Technology, Free State, 2008. http://hdl.handle.net/11462/42.
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Thesis (M. Tech.) -- Central University of Technology, Free State, 2008As the tendency to use sol id freeform fabrication (SFF) technology for the manufacture of end use parts grew, so too did the need for a set of general guidelines that would aid designers with designs aimed specifically for rapid manufacture. Unfortunately, the revolutionary additive nature of SFF technology left certain fundamental principles of conventional design for manufacture and assembly outdated. This implied that whole chapters of theoretical work that had previously been done in this field had to be revised before it could be applied to rapid manufacturing. Furthermore, this additive nature of SFF technology seeded a series of new possibilities and new advantages that could be exploited in the manufacturing domain, and as a result drove design for rapid manufacturing principles even further apart from conventional design for manufacture and assembly philosophy. In this study the impact that rapid manufacture had on the conventional product development process and conventional design for manufacture and assembly guidelines were investigated. This investigation brought to light the inherent strengths and weaknesses of SFF, as well as the design for manufacture and assembly guidelines that became invalid, and consequently lead directly to the characterization of a set of design for rapid manufacture guidelines.
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Fozzard, Gary James Walter. „Simulation of clothing manufacture“. Thesis, Manchester Metropolitan University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329525.
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There is considerable pressure on the U.K. clothing industry to remain competitive in the face of foreign competition. Market forces and the trend of decreasing contract sizes have produced perceived problems with current methods of production which, coupled with the inertia to radical change, justify research. Computer simulation is an established production management tool but its potential in clothing manufacture could not be inferred. Concentrating on progressive bundle systems as the dominant method of production, this research considers the capacity of simulation in this context. Factory-based studies identified factors affecting system performance which allowed a conceptual model with high face validity to be defined. The requirement to handle complex supervisory control strategies led to the identification of visual interactive simulation as an experimental route. A computerised model, with an appropriate user interface and reporting facilities, was developed in the ~Siman si@ulat~£~~Dguage __ This was supported by animated graphics which played a substantial role in the attainment of face validity. Replication was considered to be essential for sound estimates of system performance to be obtained from this stochastic model but, as interactive control works against replication, steps were taken to reduce compromise. Software development facilitated an experimental technique that employed interaction to develop a control strategy, which then became embedded in the model for replication. By providing control consistency between replications, a more reliable assessment of system sensitivity to stochastic variability was possible. Pilot runs and single factor analysis enabled the effect of controllable factors on system performance to be quantified. Supervisory control was found to have a major effect on system performance so that the need for consistency in interaction was amplified. Considering alternative experimental methods and the practical use of the model, application areas for simulation in the absence of real time data capture were identified and demonstrated. Each application offered significant advantage over currently available planning methods and the use of simulation was supported. Information from the model can be gained about the design and control of progressive bundle lines at the pre-production phase, and the output of performance indicators can be useful in assessing real production lines. The evidence presented by this research illustrates that animated simulation can provide insight that is otherwise unobtainable.
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Al, Mortadi Noor. „Computer Aided Design/Aided Manufacture/Additive Manufacturing applications in the manufacture of dental appliances“. Thesis, Cardiff Metropolitan University, 2014. http://hdl.handle.net/10369/6527.
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Ates, Aylin. „Design, manufacture and engineering management“. Thesis, University of Strathclyde, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501887.
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Galano, Marina L. „Manufacture and characterisation of nanoquasicrystalline“. Thesis, University of Oxford, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.534203.
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Harrison, D. „Adaptive techniques in robotic manufacture“. Thesis, University of Portsmouth, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383286.
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Mohd, Ghazi Tinia Idaty. „Heterogeneous photocatalysis for chemicals manufacture“. Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.614672.
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Lakhdar, K. „Production planning of biopharmaceutical manufacture“. Thesis, University College London (University of London), 2006. http://discovery.ucl.ac.uk/1444912/.
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Multiproduct manufacturing facilities running on a campaign basis are increasingly becoming the norm for biopharmaceuticals, owing to high risks of clinical failure, regulatory pressures and the increasing number of therapeutics in clinical evaluation. The need for such flexible plants and cost-effective manufacture pose significant challenges for planning and scheduling, which are compounded by long production lead times, intermediate product stability issues and the high cost - low volume nature of biopharmaceutical manufacture. Scheduling and planning decisions are often made in the presence of variable product titres, campaign durations, contamination rates and product demands. Hence this thesis applies mathematical programming techniques to the planning of biopharmaceutical manufacture in order to identify more optimal production plans under different manufacturing scenarios. A deterministic mixed integer linear programming (MILP) medium term planning model which explicitly accounts for upstream and downstream processing is presented. A multiscenario MILP model for the medium term planning of biopharmaceutical manufacture under uncertainty is presented and solved using an iterative solution procedure. An alternative stochastic formulation for the medium term planning of biomanufacture under uncertainty based on the principles of chance constrained programming is also presented. To help manage the risks of long term capacity planning in the biopharmaceutical industry, a goal programming extension is presented which accounts for multiple objectives including cost, risk and customer service level satisfaction. The model is applied to long term capacity analysis of a mix of contractors and owned biopharmaceutical manufacturing facilities. In the final sections of this thesis an example of a commercial application of this work is presented, followed by a discussion on related validation issues in the biopharmaceutical industry. The work in this thesis highlighted the benefits of applying mathematical programming techniques for production planning of biopharmaceutical manufacturing facilities, so as to enhance the biopharmaceutical industry's strategic and operational decision-making towards achieving more cost-effective manufacture.
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Khan, Muhammad Farhan. „Design optimisation for stent manufacture“. Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/52353/.
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Intravascular stents of various designs are currently used to prop open diseased arteries and there is evidence that different stent geometries have different in-stent restenosis rates. The majority of commercially available stents are designed generically to fit all individuals. Recent advances in imaging and catheter technologies, however, allow measurement of lesion shape and stiffness. Incorporating patient specific data into the stent design process could enable the development of customised stents. Considering the variety of lesion types, it is envisaged that better outcomes will be achieved if a stent is custom designed in such a way that it has variable radial stiffness longitudinally to hold the varying pressure of plaque and healthy artery at the same time while maintaining an acceptable lumen diameter. This type of operation is suitable for topology optimisation potentially allowing for optimal material distribution of a stent. The primary aim of this research is to develop new stent designs for a set of plaque types and investigate the final radius of the lumen after stent implantation. Stent geometries were obtained by topology optimisation for minimised compliance under different stenosis levels and plaque materials. Three types of stenosis levels by area, i.e. 30%, 40% and 50% with each type having three different plaque material properties i.e. calcified, cellular and hypocellular were studied. The optimisation results were transformed to clear design concepts and their performance was evaluated by implanting them in their respective stenosed artery types using finite element analysis. The results were compared with a generic stent in similar arteries, which showed that the new designs showed less recoil. In the hardest (calcified) of plaques studied, topology optimised designs overall resulted in 2%, 2% and 6% residual area stenosis compared to 10%, 29% and 35% from the generic design in arteries with 30%, 40% and 50% stenosis respectively. It was shown that higher material distribution resulted in the central region of the stent in order to resist implantation recoil due to higher plaque compressive loads. Additive manufacturing (AM) was utilised to validate the computational approach used in this thesis. This work provides a proof of concept for stents tailored to specific lesions in order to minimise recoil and maintain a patent lumen in stenotic arteries.
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Pilson, Richard Ryan. „Automated Manufacture of Spinal Instrumentation“. Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/31278.
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Current scoliosis corrective surgeries may include the use of multiple instrumentation devices including screws, wires, nuts, and rods. The instrumentation in most cases is implemented in its native form. However, the instrumentation rods must be contoured to a desired shape prior to fixation to the spine. The contouring of the instrumentation rod is currently performed manually and may require significant time for completion. This results in an increase of operation time and reduced accuracy of the instrumentation rod. The feasibility of automating the contouring process was studied to determine if the time required to contour a rod could be reduced and if the accuracy of the rod could be improved.
This study built upon a previous effort to construct a prototype that would automate the manufacture of spinal instrumentation rods. The Spinal Instrumentation Bending Prototype (SIBP) focused on ease of use, time of manufacture, and accuracy. In order to complete the manufacturing process, the current SIBP uses a set of three dimensional control points that represent the desired contour of the rod. These control points are translated into manufacturing inputs that control the SIBP. The control application for the SIBP contains local and global feedback routines that correct for any manufacturing errors. A comparative study was made between the SIBP and an experienced orthopedic surgeon to determine the level of bending accuracy improvement.Master of Science
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Huang, Yean-Jenq. „Optimal Integrated broaching manufacture process“. Ohio University / OhioLINK, 1989. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1182436807.
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Aremu, Adedeji. „Topology optimization for additive manufacture“. Thesis, Loughborough University, 2013. https://dspace.lboro.ac.uk/2134/12833.
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Additive manufacturing (AM) offers a way to manufacture highly complex designs with potentially enhanced performance as it is free from many of the constraints associated with traditional manufacturing. However, current design and optimisation tools, which were developed much earlier than AM, do not allow efficient exploration of AM's design space. Among these tools are a set of numerical methods/algorithms often used in the field of structural optimisation called topology optimisation (TO). These powerful techniques emerged in the 1980s and have since been used to achieve structural solutions with superior performance to those of other types of structural optimisation. However, such solutions are often constrained during optimisation to minimise structural complexities, thereby, ensuring that solutions can be manufactured via traditional manufacturing methods. With the advent of AM, it is necessary to restructure these techniques to maximise AM's capabilities. Such restructuring should involve identification and relaxation of the optimisation constraints within the TO algorithms that restrict design for AM. These constraints include the initial design, optimisation parameters and mesh characteristics of the optimisation problem being solved. A typical TO with certain mesh characteristics would involve the movement of an assumed initial design to another with improved structural performance. It was anticipated that the complexity and performance of a solution would be affected by the optimisation constraints. This work restructured a TO algorithm called the bidirectional evolutionary structural optimisation (BESO) for AM. MATLAB and MSC Nastran were coupled to study and investigate BESO for both two and three dimensional problems. It was observed that certain parametric values promote the realization of complex structures and this could be further enhanced by including an adaptive meshing strategy (AMS) in the TO. Such a strategy reduced the degrees of freedom initially required for this solution quality without the AMS.
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Cartree, Ryan R., Kyle Hollingshead, Elisabeth Lynn und Matt West. „HFE-143 Green Refrigerant Manufacture“. Thesis, The University of Arizona, 2009. http://hdl.handle.net/10150/192298.
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West, Matthew. „HFE-143 Green Refrigerant Manufacture“. Thesis, The University of Arizona, 2009. http://hdl.handle.net/10150/193031.
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Athinarayanan, Madhusudhanan. „Foam filled corrugated board manufacture“. Thesis, University of Manchester, 2007. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.676723.
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Perez, Kevin Blake. „Hybridization of PolyJet and Direct Write for the Direct Manufacture of Functional Electronics in Additively Manufactured Components“. Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/76944.
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The layer-by-layer nature of additive manufacturing (AM) allows for access to the entire build volume of a component during manufacture including the internal structure. Voids are accessible during the build process and allow for components to be embedded and sealed with subsequently printed layers. This process, in conjunction with direct write (DW) of conductive materials, enables the direct manufacture of parts featuring embedded electronics, including interconnects and sensors.
The scope of previous works in which DW and AM processes are combined has been limited to single material AM processes. The PolyJet process is assessed for hybridization with DW because of its multi-material capabilities. The PolyJet process is capable of simultaneously depositing different materials, including rigid and elastomeric photopolymers, which enables the design of flexible features such as membranes and joints. In this work, extrusion-based DW is integrated with PolyJet AM technology to explore opportunities for embedding conductive materials on rigid and elastomeric polymer substrates. Experiments are conducted to broaden the understanding of how silver-loaded conductive inks behave on PolyJet material surfaces.
Traces of DuPont 5021 conductive ink as small as 750?m wide and 28?m tall are deposited on VeroWhite+ and TangoBlack+ PolyJet material using a Nordson EFD high-precision fluid dispenser. Heated drying at 55°C is found to accelerate material drying with no significant effect on the conductor's geometry or conductivity. Contact angles of the conductive ink on PolyJet substrates are measured and exhibit a hydrophilic interaction, indicating good adhesion. Encapsulation is found to negatively impact conductivity of directly written conductors when compared to traces deposited on the surface. Strain sensing components are designed to demonstrate potential and future applications.Master of Science
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Halvarsson, Sören. „Manufacture of straw MDF and fibreboards“. Doctoral thesis, Mittuniversitetet, Institutionen för naturvetenskap, teknik och matematik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-11732.
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The purpose of this thesis was to develop an economical, sustainable, and environmentally friendly straw Medium Density Fibreboard (MDF) process, capable of full-scale manufacturing and to produce MDF of requested quality. The investigated straw was based on wheat (Triticum aestivum L.) and rice (Oryzae sativa L.). In this thesis three different methods were taken for manufacture of straw MDF; (A) wheat-straw fibre was blowline blended with melamine-modified urea-formaldehyde (MUF), (B) rice-straw fibre was mixed with methylene diphenyl diisocyanate (MDI) in a resin drum-blender, and (C) wheat-straw fibre was activated in the blowline by the addition of Fenton’s reagent (H2O2/Fe2+) for production of non-resin MDF panels. The MUF/wheat straw MDF panels were approved according to the requirements of the EN standard for MDF (EN 622-5, 2006). The MDI/rice-straw MDF panels were approved according to requirements of the standard for MDF of the American National Standard Institute (ANSI A208.2-2002). The non-resin wheat-straw panels showed mediocre MDF panel properties and were not approved according to the requirements in the MDF standard. The dry process for wood-based MDF was modified for production of straw MDF. The straw MDF process was divided into seven main process steps. 1. Size-reduction (hammer-milling) and screening of straw 2. Wetting and heating of straw 3. Defibration 4. Resination of straw fibre 5. Mat forming 6. Pre-pressing 7. Hot-pressing The primary results were that the straw MDF process was capable of providing satisfactory straw MDF panels based on different types of straw species and adhesives. Moreover, the straw MDF process was performed in pilot-plant scale and demonstrated as a suitable method for producing straw MDF from straw bales to finished straw MDF panels. In the environmental perspective the agricultural straw-waste is a suitable source for producing MDF to avoid open field burning and to capture carbon dioxide (CO2), the biological sink for extended time into MDF panels, instead of converting straw directly into bio energy or applying straw fibre a few times as recycled paper. Additionally, the straw MDF panels can be recycled or converted to energy after utilization. A relationship between water retention value (WRV) of resinated straw fibres, the thickness swelling of corresponding straw MDF panels, and the amount of applied adhesive was determined. WRV of the straw fibre increased and the TS of straw MDF declined as a function of the resin content. The empirical models developed were of acceptable significance and the R2 values were 0.69 (WRV) and 0.75 (TS), respectively. Reduced thickness swelling of MDF as the resin content is increased is well-known. The increase of WRV as a function of added polymers is not completely established within the science of fibre swelling. Fortunately, more fundamental research can be initiated and likely a simple method for prediction of thickness swelling of MDF by analysis of the dried and resinated MDF fibres is possible.Syftet med denna avhandling var att lägga grunden för en ekonomisk, hållbar och miljövänlig MDF process för halmråvara, kapabel för fullskalig produktion av MDF och goda skivegenskaper. Framställningen av MDF skivor utgick från halm av vete (Triticum aestivum L.) och ris (Oryzae sativa L.). Tre olika metoder användes för att producera MDF av halm; (A) fibrer av vetehalm belimmades i blåsledning med ett melaminmodifierat urea-formaldehydlim (MUF), (B) fibrer av rishalm belimmades i en limblandare med metylen difenyl diisocyanate (MDI), (C) Limfria MDF skivor av vetehalm framställdes med aktivering av fibrer genom tillsats av Fenton´s reagens (H2O2/Fe2+) i blåsledning utan någon tillsats av syntetiskt lim. Sammanfattningsvis kan det understrykas att framställda MDF-skivor av MUF/vetehalm var godkända enligt standard för MDF (EN 622-5, 2006). Dessutom var framställda MDF skivor av MDI/rishalm också godkända enligt krav i standard för MDF ”American National Standard Institute” (ANSI A2008.2-2002). Limfria vetehalmskivor visade på måttliga skivegenskaper och klarade inte kraven i MDF standard. Fiberframställningsprocessen för MDF modifierades till en produktion utgående från halm. MDF processen för halm delades upp i sju primära processoperationer. (1) Storleksreducering och sållning av halm (2) Vätning och uppvärmning av halm (3) Defibrering (4) Belimning av halmfiber (5) Mattformning (6) Förpressning (7) Pressning De viktigaste resultaten från denna studie är att MDF av halm kunde produceras utgående från olika typer av halmsorter och lim. Dessutom utfördes MDF-processen i pilotskala och visade på en lämplig metod för framställning av MDF-skivor från halmbalar till färdiga halmfiberskivor. Det miljömässiga perspektivet på att använda jordbruksavfall till framställning av halmskivor är att undvika förbränning av halm ute på fältet, men det är även möjligt att binda koldioxid (CO2) i halmskivor under längre tid än att omsätta halmråvaran omedelbart som bioenergi eller använda halmfiber som returpapper några få gånger. Dessutom kan MDF återanvändas eller bli omsatt till energi efter användning. Ett förhållande mellan ”water retention value” (WRV), av belimmade halmfiber, tjocklekssvällning för motsvarande MDF av halmskivor och mängden av tillsatt lim vid olika nivåer har undersökts. Med ökande limhalt tilltog WRV fibersvällning, vidare minskade tjocklekssvällning för motsvarande MDF skivor. De framtagna empiriska modellerna var godtagbara och beräknade R2 värden var 0.69 (WRV) och 0.75 (TS). Minskad tjocklekssvällning med ökad limhalt är dokumenterad sen tidigare. Ökad fibersvällning WRV vid tillsats av polymerer (limmer) är inte fullständigt etablerad inom vetenskapen för fibersvällning. Lyckligtvis kan grundläggande forskning initieras och sannolikt föreligger en enkel metod för att prediktera tjocklekssvällning av MDF genom analyser av torkade och belimmad MDF fiber.
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Maloney, Soren E. „Acoustics and manufacture of Caribbean steelpans“. Thesis, University of Cambridge, 2011. https://www.repository.cam.ac.uk/handle/1810/238665.
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The Caribbean steelpan is a pitched percussion instrument that originated in Trinidad and Tobago during the Second World War. Despite several research initiatives to improve the making of this relatively new instrument, several areas remain unaddressed. This thesis presents new approaches to help improve the making of the instrument. These approaches are situated in the production, vibration and material aspect of the steelpan. A novel sheet forming technology termed Incremental Sheet Forming (ISF) is applied to the production of miniature steelpan dishes. The thickness distribution in the wall of the ISF dishes is compared to the wall thickness distribution in a traditionally formed steelpan dish and a wheeled dish. Unlike traditional forming and wheeling, ISF produces stretching in only a portion of the walls of the formed dishes. Multi-pass ISF is used to extend the stretched zone but this extension is minimal. A break even analysis is also applied to investigate the fiscal viability of ISF application to the production of miniature and full size steelpan dishes. The application of ISF to steelpan making is found to be commercially profitable but could be jeopardised by the tuning stage of the steelpan making process. A preliminary study on the effect of impact on tone stability is conducted on a pair of notes on a fullsize steelpan and detuning is found more likely to occur by repeated impact of the note at its centre. Mode confinement in test-pans is also investigated. ISF is used to produce miniature test-pans with test-notes that are geometrically identical to notes on full size pans. It is possible to confine modes by varying the curvature of the bowl surrounding the test-note. The number of localised modes in the test-note increases as the radius of curvature of the surrounding bowl increases. The natural frequency of the first confined mode in the test-notes is sensitive to material springback in ISF and the mechanism of confinement appears to be due to the change in geometry that occurs between the flat test-note region and the bowl wall. This control of mode confinement may find use in future efforts to completely or partially automate the steelpan making process. Material damping and mechanical properties in low-carbon steel used to produce steelpans are researched. Damping and mechanical properties are extracted from low-carbon steel that is subjected to identical stages to the steelpan production process. Material damping trends suggest that an annealing temperature between 300°C and 400°C would be appropriate for the heat treatment of steelpans. Air-cooled and water-quenched low-carbon specimens exhibit comparable damping trends. Hardness increases in cold formed low-carbon specimens is attributed to strain hardening and not strain ageing. Investigation of damping trends and mechanical properties in ultra low bake-hardenable and interstitial-free steels reveals that a wider range of low-carbon steels may be suitable for steelpan making.
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Akbary-Safa, Mahnaz. „Computer aided inspection in engineering manufacture“. Thesis, Imperial College London, 1992. http://hdl.handle.net/10044/1/8346.
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Zhai, Yun. „Early cost estimation for additive manufacture“. Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7856.
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Additive Manufacture (AM) is a novel manufacturing method; it is a process of forming components by adding materials. Owing to material saving and manufacturing cost saving, more and more research has been focused on metal AM technologies. WAAM is one AM technology, using arc as the heat sources and wire as the material to create parts with weld beads on a layer-by-layer basis. The process can produce components in a wide range of materials, including aluminum, titanium and steel. High deposition rate, material saving and elimination of tooling cost are critical characteristics of the process.
Cost estimation is important for all companies. The estimated results can be used as a datum to create a quote for customers or evaluate a quote from suppliers, an important consideration for the application of WAAM is its cost effectiveness compared with traditional manufacture methods. The aim of this research is to find a way to develop a cost estimating method capable of providing manufacturing cost comparison of WAAM with CNC. A cost estimation model for CNC machining has been developed. A process planning approach for WAAM was also defined as part of this research. An Excel calculation spreadsheet was also built and it can be easily used to estimate and compare manufacture cost of WAAM with CNC.
Using the method developed in this research, the cost driver analysis of WAAM has been made. The result shows that reduced material cost is the biggest cost driver in WAAM. The cost comparison of WAAM and CNC also has been made and the results show that with the increase of buy-to-fly ratio WAAM is more economical than CNC machining.
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Progoulakis, Losif. „Heated tooling for aerospace composites manufacture“. Thesis, University of Plymouth, 2004. http://hdl.handle.net/10026.1/1105.
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The increasingly high capital investment required for large autoclaves, ovens and facilities for the processmg of large composite components creates a number of financial constraints for the development and manufacturing of larger composite aircraft products. This thesis has investigated the use of heated tooling as an alternative to the use of autoclave and oven curing. A design and development methodology for heated tools has been proposed while a number of heated tooling options have been identified and described. Three representative heated tool options using heater mats, electro-conductive textiles and wire heater elements have been evaluated. The curing capability of a prototype heated tool incorporating wire heater elements has been proved by carrying out a number of curing tests on RFI (Resin Fihn Infusion) laminates. The moulded laminates indicate that a 78-83% extent of cure is achieved prior to post-cure. The fibre and void content of cured laminates has also been verified through acid digestion and microscopy, where an acceptable fibre volume fraction (Vf) of 55-57% and a void content of less than 2% have been achieved. The usefulness of ID and 3D thermal Finite Element Analysis for the design and simulation of heated tooling has also been studied. A manufacturing and cost analysis study carried out has identified potential production implications, while the cost effectiveness of heated tooling compared to oven and autoclave processmg has been indicated. Cost reductions are noted in capital investments, operational costs and production set-up costs per part. The work described in this thesis gives valuable information for the implementation of heated tooling as a new processing method for aerospace composite products. The information can prove useful when considermg the processing options of large composite parts such as wing spars, fan cowl doors and wing skins.
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Harrop, Nicholas M. „Recycling for newsprint manufacture : deinking fundamentals“. Thesis, University of Manchester, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.616284.
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It has long been known that waste newsprint can be deinked effectively only if a proportion of coated waste is added to it. Coated waste paper is not always in good supply, and can cost more than waste newsprint. The present research has thrown new light on why coated waste is required. In flotation deinking, two distinct processes act to separate ink from pulped stock. Firstly, air bubbles rising through the liquid phase collect ink particles and carry them to the surface. The ink particles are then retained by the foam on the surface until it is removed. The commercial deinking plant that was the subject of the present study uses a proprietary chemical, which is intended to act effectively in both processes. Chemical speciation has shown that the chemical species in the foam and in the bulk solution have similar thermodynamic properties. This implies that the chemical process operates independently of the presence of coated waste. Comparison of results gathered in full-scale and in pilot deinking equipment has shown that the foam is more stable when the waste paper being deinked contains coated waste. The key role of coated material is therefore to stabilise the foam, and so prevent re-mixing of ink with the deinked fibre slurry. These facts suggest that to achieve good deinking without having to use coated waste, other means of maintaining foam stability must be sought.
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Lackenby, Catherine Louise. „Strategic relationships in global garment manufacture“. Thesis, University of Sunderland, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393051.
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Richardson, Gary P. „Integrated bioprocesses for acrylic polymer manufacture“. Thesis, University of Huddersfield, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405179.
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Xiao, Di-Chen. „Manufacture of novel bearings by laser“. Thesis, University of Liverpool, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321252.
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Spragg, Jon Edward. „Modelling supervisory behaviour in clothing manufacture“. Thesis, Manchester Metropolitan University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278537.
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Battocchio, Francesco. „Manufacture and characterisation of spunbonded nonwovens“. Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708457.
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Evans, S. E. K. „Applied photogrammetry in orthopaedic implant manufacture“. Thesis, University of Liverpool, 2018. http://livrepository.liverpool.ac.uk/3020338/.
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Taylor, Joel Edward. „Structure development during crumb chocolate manufacture“. Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609686.
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Atkinson, Juan Pablo. „Cost model for bipolar plate manufacture“. Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71625.
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Thesis (MScEng)--Stellenbosch University, 2012.ENGLISH ABSTRACT: This thesis gives a cost model for the manufacture of bipolar plates in South Africa. The methods for the manufacture considered are machining, using a micro-milling machine, and compression moulding. The focus of this thesis is on compression moulding. Details of the work done towards developing and validating the models are described, and then the cost models are discussed in detail. The results of the analysis done using the cost model is given with attention paid to the effect of changing design parameters, such as channel size and flow field area, and of the cost of production for both methods over various production volumes. The thesis concludes that compression moulding becomes the better option for production volumes greater than 324 bipolar plates, with a cost that eventually reaches close to R140 per plate for high enough production volumes (over 5000). The cost to produce 1000 plates using compression moulding is estimated at R294 per plate. An increase of the channel size gives a small reduction in the total cost, while the increase in cost with an increase in flow field area is large.
AFRIKAANSE OPSOMMING: Hierdie tesis gee 'n koste-model vir die vervaardiging van bipolêre plate in Suid- Afrika. Die vervaardigingsmetodes wat oorweeg word, is masjinering deur 'n mikro-freesmasjien en persvorming. Die fokus van hierdie tesis is op persvorming. Die besonderhede van die ontwikkeling en validering van die modelle word beskryf, en daarna word die modelle in besonderhede beskryf. Die resultate van 'n analise wat met die koste-model gedoen is, word daarna gegee, met die oorweging van die verandering van ontwerp-parameters soos die vloeikanaalgrootte en vloeiveld-area, en van die koste van vervaardiging vir beide metodes vir verskeie produksievolumes. Die tesis kom tot die slotsom dat persvorming die voorkeurproses is vir produksievolumes groter as 324 bipolêre plate, met 'n koste wat tot naastenby R140 per plaat daal vir hoë produksievolumes (meer as 5000). Die koste om 1000 plate met persvorming te maak, word op R294 per plaat beraam. 'n Toename in kanaalgrootte gee 'n klein vermindering in die totale koste, terwyl die toename in koste groot is wanneer die vloeiveld-area toeneem.
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Wharton, J. T. „Structural functional surface design and manufacture“. Thesis, Liverpool John Moores University, 2018. http://researchonline.ljmu.ac.uk/7782/.
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The main purpose of this investigation was to explore the potential benefits of structural functional surfaces using facilities available within the University. The potential benefits were demonstrated by applying functional surfaces to a set of particular engineering applications. The thesis mainly concentrated on improving the frictional performance of a surface structure for hydrodynamic bearing application. This thesis has also included some preliminary investigation into drag-reducing riblet structures but this chapter mainly discusses the development of a novel experimental apparatus which is needed for precise boundary layer profile measurements and also to obtain the actual surface drag for each sample. To be able to assess these surfaces experimentally, they first, have to be manufactured. So, an extensive literature review of current manufacturing technologies was carried out. Each manufacturing method was ranked in its ability to cost-effectively produce surfaces with accuracy and repeatability also being considered. It was concluded that rolling, currently, has the best ability to structure large surface areas with the lowest costs associated. Other manufacturing methods, such as laser surface texturing, provide excellent repeatability and accuracy as well as the ability to create complex surface structures but is incredibly time-consuming for large surface areas. It was suggested that a hybrid of multiple manufacturing technologies would be incredibly useful for structuring surfaces. By combining rolling with more elaborate surface texturing methods (i.e. use a method such as LST to texture the roller surface), it is possible to amplify the productivity of less efficient methods, substantially. Before any journal components were textured, it was decided to test a batch of ground components. These components were finished with an abrasive tape process. The process parameters were varied for each sample and by doing this, a set of components with different roughness characteristics should have been obtained. The components were measured for 2D roughness parameters, 3D roughness parameters and surface energy. The components were tested on a tribometer apparatus in order to obtain a coefficient of friction (COF) for each sample. Correlation coefficients were then generated for the different surface measurements against COF, so that any strong correlations or trends could be identified. The idea was to try and obtain a reliable performance indicator (PI) so that frictional losses could be identified. It was found that the roughness parameters Sc (core void voume), Ssc (mean summit curvature) and Rku/Sku (profile/surface kurtosis) showed promise in the ability to predict the performance of a surface. The next stage was to texture the surface of the journal component. This would done by the application of the type III texturing grinding process, described by Stepien (Surface Engineering, 24: 219-225), to the cylindrical grinding process. Some initial components were manufactured and the textures generated were found to be of an ellipsoidal shape. In order to guarantee the benefits of such surfaces, the configuration of the surface pattern has to be optimised. A python script was developed during this investigation in order to automate a full modelling process. The computational fluid dynamics (CFD) modelling used a full 3D Navier-Stokes approximation. This script was used in conjunction with the Taguchi optimisation technique and a best surface configuration was found, resulting in a maximum surface drag reduction of 16.6% at a 3μm clearance. Further grinding trials were performed and the input parameters of the process were designed so that surface patterns were close to the recommendations of the optimisation process. The performance of the textured samples was impressive, with a maximum reduction in COF of 18.4% seen against a non-textured component with similar average roughness (Sa) value. Again, all components were measured for the aforementioned roughness parameters and surface energy. Sku continued to predict the best-performing component, showing promise as PI for both non-textured and textured samples.
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Williams, Howard R. „Compound semiconductor material manufacture, process improvement“. Thesis, University of South Wales, 2002. https://pure.southwales.ac.uk/en/studentthesis/compound-semiconductor-material-manufacture-process-improvement(d0373158-08d9-4332-9278-f5353203dcd0).html.
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IQE (Europe) Ltd. manufactures group III/V compound semiconductor material structures, using the Metal Organic Vapour Phase Epitaxy process. The manufactured ranges of semi-conducting materials are relative to discrete or multi-compound use of Gallium Arsenide or Indium Phosphide [III/V]. For MOVPE to compete in large-scale markets, the manufacturing process requires transformation into a reliable, repeatable production process. This need is identified within the process scrap percentage of the process when benchmarked against the more mature Si-CVD process. With this wide-ranging product base and different material systems, flexible processes and systems are essential. The negative impact however, of this demanded flexibility is a complex system, resulting in instability. Minor fluctuations in time, flow, pressure, temperature, or composition in the manufacturing process, will lead to characteristic differences in the produced material [product], when comparing the prescribed run to the actual run. The product profile changes very rapidly, correspondingly the failure profile of the process is equally as dynamic, it is essential therefore that the analysis and projected activities and actions can be identified and consolidated in a timely manner. This project evaluates the process used by IQEE to manufacture III/V compound semi-conducting material structures and uses the business performance to identify the process drivers. One year's [1997] business and process information is used for a single iteration of the improvement cycle. These drivers are then utilised as operators and offer the critical weaknesses in the process related to performance blockages. Some of the techniques utilised in the process evaluation and cause derivation; are original contributions specifically derived for use with a multi-platform complex process with multiple cause and effect operators. A double reporting FMEA contributes a differing rank for like machines running differing products, offering a machine specific failure profile. A novel composite of P-diagram and process flow techniques enables determination of activity influences confirming the key failure mechanism as previously identified by the business risk analysis. This project concludes by nominating the key failure mechanism accounting for 41% of the approximate 50% scrap figure identified again within the business risk analysis. The effects attributed to this failure mechanism are 2- dimensionally analysed utilising an original double operating FMEA, plotting effect to effect for the individual causes, offering a prioritised list of failure categories. The highest priority failure mode is addressed by an equipment design exercise, resulting in an overall 10% sales potential recontribution.
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Goodman, Kendall E. „Thermoplastic prepreg manufacture by solution impregnation“. Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/42197.
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Advanced thermoplastic composites are commonly manufactured from "'prepreg" materials, where the reinforcing fibers are preimpregnated with resin. The objectives of this investigation were to identify the critical parameters in impregnation of the fiber tow by a thermoplastic solution, and to produce high quality thermoplastic prepreg. Continuous carbon fibers (AS4 and AU4) were impregnated with a thermoplastic resin solution using a research scale, single tow, drum winding prepreg machine. The parameters varied to control the degree of impregnation of the fiber tow were, weight percent polymer in solution, die size, fiber tow tension, fiber tow velocity, and the use of impregnation pins.
These parameters were varied during the prepregging operation and prepreg samples were evaluated to determine resin content. Viscosity studies were performed on the polymer solutions by means of a Rheometrics Mechanical Spectrometer. Thermogravimetric analyses were performed on the thermoplastic solution and the prepreg. Cross-sectional photomicrographs were obtained to determine the degree of impregnation and the fiber/resin distribution.
Unidirectional laminates were fabricated from the prepreg. Transverse tensile and double cantilivered beam mechanical tests were performed. Fractography photomicrographs were taken. X-Ray photoelectron spectroscopy was used to investigate the possibility of residual solvent in the laminates.
High quality prepreg was manufactured and the critical parameters in the prepregging process were identified and their effect on the prepreg was quantified.
Master of Science
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Soo, Woan Yi. „The manufacture of bioscaffolds by printing“. Thesis, Swansea University, 2010. https://cronfa.swan.ac.uk/Record/cronfa42351.
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Printing technology is mainly used for graphic arts and packaging applications, but also is a potential technology for the micro manufacture of electronic devices, biosensors and tissue engineering scaffolds. The main goal of this research is to print fine lines of biopolymer by means of volume printing processes. To assess the feasibility of printing fine features for bioscaffolds using conventional printing technology, an experimental investigation into the rheological behaviour of biopolymer inks was conducted. This is because the rheological characteristics of the biopolymers have a significant influence on the performance of different printing processes. The biopolymers undergo significant phase transition which affects the printed products. The rheological tests focus on ink viscosity, viscoelastic and gelation properties. Gelatine appeared to be more favourable than collagen for scaffolds fabrication by printing technologies. Thus this study was mainly focused on aqueous gelatine solution as printing ink. All inks display shear-thinning and thixotropic behaviours which are important for good printing. The temperature ramp and multi-frequency sweep tests yield information on gelation temperature and gel point. The rate of ordering and gel formation of biopolymer inks was found to be strongly concentration-, temperature- and time-dependent. An increase in gelatine concentrations caused a reduction in the dynamic surface tension of the inks. Printing conditions that are compatible with printing biopolymer inks were being optimised in terms of operation temperature interval to accommodate phase transition. Three printing processes inkjet printing, flexography and screen printing were evaluated for printing fine features of biopolymers. Surfactants were used to lower the ink surface tension to below 30 mN/m, so that the ink could be jetted onto substrate. These printing methods are aimed to produce cost effective bioscaffolds in mass production. The quality of printed lines was examined in terms of width and film thickness to establish the best printing method for gelatine printing. Fine lines printed by inkjet and flexographic printing processes were mostly broken. Screen printing process looks more promising because the printed gelatine fine lines showed the best quality. The line width and line film thickness measured were more consistent and closer to the desired dimensions. A laboratory screen printing trial was conducted using Lie orthogonal array technique to investigate the effect of process parameters on the reproduction of the screen printed fine gelatine lines in terms of line width and film thickness. Six parameters studied were ink type, mesh type, squeegee hardness, snap-off gap, squeegee speed and squeegee pressure. The most significant parameter was the ink type, followed by snap-off gap and mesh type. The effect of squeegee parameters (squeegee type, speed and pressure) was considered insignificant. The orientation has an effect on line width but insignificant effect on line film thickness. Most process parameters had interactions with one another which complicated the optimisation of the process parameters.
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Poodts, Ezequiel <1984>. „Composite materials design, manufacture and evaluation“. Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5402/1/POODTS_EZEQUIEL_TESI.pdf.
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Fibre-Reinforced-Plastics are composite materials composed by thin fibres with high mechanical properties, made to work together with a cohesive plastic matrix. The huge advantages of fibre reinforced plastics over traditional materials are their high specific mechanical properties i.e. high stiffness and strength to weight ratios. This kind of composite materials is the most disruptive innovation in the structural materials field seen in recent years and the areas of potential application are still many.
However, there are few aspects which limit their growth: on the one hand the information available about their properties and long term behaviour is still scarce, especially if compared with traditional materials for which there has been developed an extended database through years of use and research.
On the other hand, the technologies of production are still not as developed as the ones available to form plastics, metals and other traditional materials. A third aspect is that the new properties presented by these materials e.g. their anisotropy, difficult the design of components.
This thesis will provide several case-studies with advancements regarding the three limitations mentioned.
In particular, the long term mechanical properties have been studied through an experimental analysis of the impact of seawater on GFRP. Regarding production methods, the pre-impregnated cured in autoclave process was considered: a rapid tooling method to produce moulds will be presented, and a study about the production of thick components. Also, two liquid composite moulding methods will be presented, with a case-study regarding a large component with sandwich structure that was produced with the Vacuum-Assisted-Resin-Infusion method, and a case-study regarding a thick con-rod beam that was produced with the Resin-Transfer-Moulding process. The final case-study will analyse the loads acting during the use of a particular sportive component, made with FRP layers and a sandwich structure, practical design rules will be provided.
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Poodts, Ezequiel <1984>. „Composite materials design, manufacture and evaluation“. Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5402/.
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Fibre-Reinforced-Plastics are composite materials composed by thin fibres with high mechanical properties, made to work together with a cohesive plastic matrix. The huge advantages of fibre reinforced plastics over traditional materials are their high specific mechanical properties i.e. high stiffness and strength to weight ratios. This kind of composite materials is the most disruptive innovation in the structural materials field seen in recent years and the areas of potential application are still many.
However, there are few aspects which limit their growth: on the one hand the information available about their properties and long term behaviour is still scarce, especially if compared with traditional materials for which there has been developed an extended database through years of use and research.
On the other hand, the technologies of production are still not as developed as the ones available to form plastics, metals and other traditional materials. A third aspect is that the new properties presented by these materials e.g. their anisotropy, difficult the design of components.
This thesis will provide several case-studies with advancements regarding the three limitations mentioned.
In particular, the long term mechanical properties have been studied through an experimental analysis of the impact of seawater on GFRP. Regarding production methods, the pre-impregnated cured in autoclave process was considered: a rapid tooling method to produce moulds will be presented, and a study about the production of thick components. Also, two liquid composite moulding methods will be presented, with a case-study regarding a large component with sandwich structure that was produced with the Vacuum-Assisted-Resin-Infusion method, and a case-study regarding a thick con-rod beam that was produced with the Resin-Transfer-Moulding process. The final case-study will analyse the loads acting during the use of a particular sportive component, made with FRP layers and a sandwich structure, practical design rules will be provided.
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Kulkarni, Ambarish. „Design and manufacture of car carrier“. Thesis, Queensland University of Technology, 2010.
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Currently the loading of cars in car carrier is done manually by the truck drivers. The drivers load car carrier by climbing over the height of 1.5 meters, which is limitation in existing designs. While loading cars on the top of the prime mover, driver needs to reach top of the car carrier to load and strap cars in positions above 1.5 meters. This cause's potential risks on falls from heights; identified as an issue in car carrier sector by OHS authorities.
This research focuses on health and safety issues in present car carriers and improvement in designing of a car carrier, which eliminates loading of cars above 1.5 meters from ground level. This research develops a new car carrier with improved design mechanisms to avoid the climbing of the driver over the height of 1.5 meters without compromising on specifications of car carrier, including number of cars, variety of cars like SUV, small cars etc.
For the first time in the sector, car carrier is developed which will be capable of loading eight cars and safe by design due to elimination of drivers climbing on identified risk areas. After a short review of historic origin of the sector and identifying problems in present car carriers, research emphasises on development of car carrier to overcome falls related issues. Discussions on different layouts, to resolve problems identified and keeping design complaint with ADR and OHS regulations are presented. Latest techniques in product development including virtual design process (VDP), computer aided design (CAD), product data management (PDM), and finite element analyses (FEA) were used throughout car carrier designs for validation and verifications.
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Donoghue, Jack. „Hybrid additive manufacture and deformation processing for large scale near-net shape manufacture of titanium aerospace components“. Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/hybrid-additive-manufacture-and-deformation-processing-for-large-scale-nearnet-shape-manufacture-of-titanium-aerospace-components(5bb9e7db-824e-46e2-a832-c2780e15d6b8).html.
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The titanium alloy Ti-6Al-4V has been favoured by the aerospace industry for the past several decades due to its good combination of specific mechanical properties, alongside corrosion and fatigue resistance. Titanium alloys are naturally suited to the near net shape processing technique of Additive Manufacture (AM) due to both the inherent high cost of the raw materials, and the difficulties associated with machining the alloys. Unfortunately, the combination of Ti-6Al-4V with AM has been found to lead to undesirable microstructures with respect to large columnar prior β grains being found to grow potentially across the entire height of builds. This microstructure has been shown to lead to property anisotropy and poor fatigue resistance. However, it has recently been found that the integration of an additional process step that lightly deforms the deposited material between added layers leads to the refinement of this undesirable microstructure. This work characterises the effect that two different deformation processing techniques have on two different additive manufacturing processes; the effect of peening on a laser-powder AM technique, and the effect of rolling on an electric arc-wire AM technique. In both cases far more randomly textured prior β grains were found with an average grain size of > 100 µm rather than mm long columnar grains with a common growth direction formed in the non-deformed builds. The refined β microstructure was found to lead to a reduction in texture of the room temperature alpha phase. The low stains involved (>10%) indicated that the refined grain structures did not form by traditional recrystallisation mechanisms. In-situ EBSD measurements at temperatures spanning the alpha → β phase transformation have been used to observe the growth of new β orientations from crystallographic twins in the deformed microstructure that may explain the origin of the refined grains. New β orientations were observed to grow from twinned alpha colonies and from between alpha laths, where the new β is found to grow sharing a twinning relationship with the residual β. Simulation of both of the individual processing steps under laboratory conditions has been found to successfully replicate the refinement observed in process. Orientation analysis suggests that twinning of the residual β could lead to the texture observed in the refined grains. It is therefore suggested that the refined grains are formed from β twinned regions in the deformed material growing under the alpha → β phase transformation, as the material is heated by the next added layer during AM.
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Demircubuk, Murat. „Design and manufacture of optimum porduct structure /“. View online ; access limited to URI, 2005. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3188839.
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Regan, Cynthia Lee. „A concurrent engineering framework for apparel manufacture“. Diss., This resource online, 1997. http://scholar.lib.vt.edu/theses/available/etd-07132007-143155/.
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Dejanovic, Slavko. „Manufacture and Characterization of Elastic Interconnection Micro-“. Doctoral thesis, KTH, Microelectronics and Information Technology, IMIT, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3877.
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The subject of this thesis is a new chip to substrate interconnection technique using self-aligning elastic chip sockets. This work was focused on the technology steps which are necessary to fulfill in order to realize the suggested technique. Elastic chip sockets offer a solution for several assembly and packaging challenges, such a thermo-mechanical mismatch, effortless rework, environmental compatibility, high interconnection density, high frequency signal integrity, etc.
Two of the most challenging technology aspects, metallization and etching of the silicone elastomer were studied, but also, air bubble free casting of the silicone elastomer was taken into consideration. Elastic chip sockets and single elastic micro-bump contacts of different shapes and sizes were manufactured and characterized.
The contact resistance measurements revealed that the elastic micro-bump contacts manufactured by using the developed methods require less than one tenth of the contact force to achieve the same low contact resistance as compared to commercial elastic interconnection structures.
The analysis and measurements of the high frequency properties of the elastic micro-bump structures have shown that they can operate up to several tens of GHz without a serious degradation of the signal quality.
The same methods were applied to manufacture very high density contact area array (approximately 80000 connections/cm2), which until now was achieved only using so called chip-first techniques.
The low contact resistance, the absence of environmentally harmful materials, no need of soldering, easy rework as well as capability of very high interconnecting density and very high frequency compatibility, indicates a high potential of this technique for assembly and packaging.
Moreover, the presented technology of the silicone elastomer micromachining (metallization and RIE in particular) can be used for manufacturing of other microstructures, like chemical or biological micro reactors.
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Jones, Helene Victoria. „On laminators in composites design and manufacture“. Thesis, University of Bristol, 2017. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.720826.
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Capel, Andrew J. „Design and additive manufacture for flow chemistry“. Thesis, Loughborough University, 2016. https://dspace.lboro.ac.uk/2134/21613.
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This thesis aims to investigate the use of additive manufacturing (AM) as a novel manufacturing process for the production of milli-scale chemical reaction systems. Five well developed additive manufacturing techniques; stereolithography (SL), selective laser melting (SLM), fused deposition modelling (FDM), ultrasonic additive manufacture (UAM) and selective laser sintering (SLS) were used to manufacture a number of miniaturised flow devices which were tested using a range of organic and inorganic reactions. SL was used to manufacture a range of functioning milli-scale flow devices from Accura 60 photoresin, with both simple and complex internal channel networks. These devices were used to perform a range of organic and inorganic reactions, including aldehyde and ketone functional group interconversions. Conversion of products within these reactors, were shown to be comparable to commercially available milli-scale coil reactors. More complex designs, which allowed SL parts to be integrated to existing flow and analytical instrumentation, allowed us to develop an automated reaction analysis and optimisation platform. This platform allowed precise control over the reaction conditions, including flow rate, temperature and reagent composition. We also designed a simplex type reaction optimisation software package that could input data in the form of reaction conversions, peak intensities, and thermocouple data, and generate a new set of optimal reaction conditions. SL parts which incorporated embedded analytical components were also manufactured, which allowed us to perform inline reaction analysis as a feedback method for input into the optimisation platform. Stereolithography was shown to be a highly versatile manufacturing method for designing and producing these flow devices, however the process was shown to be still limited by the range of processable materials currently commercially available. SLM was also used to manufacture a number of functioning milli-scale flow devices from stainless steel and titanium, which had simplistic internal channel designs of diameters ranging from 1 to 3 mm. Again, SLM parts were manufactured which incorporated embedded analytical components, which could be integrated into an automated reaction platform. These devices, unlike parts produced via SL, could be attached to heating platforms to allow us to perform high temperature reactions. This control over the reaction temperature formed an essential part of the reaction optimisation platform. These parts were again used to perform a ketone functional group interconversion. Internal structures of these SLM parts were also visualised via micro computed tomography (μCT or microCT) scanning as well as optical microscopy. FDM was used throughout the project as an inexpensive method of prototyping parts which were to be manufactured via more expensive manufacturing processes. This prototyping allowed the optimisation of intricate design features, such as the manufacture of an inline spectroscopic flow cell for integration with a commercially available LC system. FDM was also proposed as a customisable approach to designing and manufacturing flow devices with embedded components, however the current limitations in build resolution and materials choices severely limited the use of FDM for this application. UAM was also proposed as a novel manufacturing process whereby the build process would allow discrete components to be embedded directly into a flow channel. This was demonstrated by embedding a type-k thermocouple across a 2 mm channel. The data from this thermocouple was monitored during a heated reaction, and used as a method of determining the exact reaction conditions the reaction medium was being exposed to. SLS was also proposed as a possible manufacturing method for milli-scale flow devices, however it proved difficult to remove un-sintered powder from parts with internal channel diameters as high as 5 mm. It was shown that this powder was forming a dense semi solid, due to the large degree of shrinkage upon cooling of the SLS parts, which was compressing the powder. More research into optimum processing conditions is required before SLS could be used for the production of intricate channel networks.
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Bowers, Gemma. „Mathematical and Numerical Modelling of cofectionery manufacture“. Thesis, Aberystwyth University, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.515812.
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Bostock, R. M. „Silicon micromachining for micro-optical device manufacture“. Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596797.
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All current laser pig-tailing methods employ either glue or a weld to secure the fibre in place. This leads to difficulty in attaining initial alignment; to movement during bonding and to instability throughout the service life. Precautions are also required to avoid device damage due to glue wicking. The approach taken in the present research is to adopt a mechanical solution, eliminating the use of either glue or a weld. In addition, this must be integrated in one part with rest of the optical system to form a compatible solution. A novel solution is developed using silicon nitride clips which hold the fibre, and are fabricated as part of the substrate. This requires the selection of a process compatible material for the clips and a method to manufacture features to allow insertion of the fibre and ensure precision alignment. The manufacture of these devices is described, both where the core of the optical fibre is below the level of the silicon substrate surface, and through the use of an extension to the process, where the fibre core is above the substrate surface. The first instance is ideal for fibre-fibre and fibre-detector connection, and the second case is required for fibre to device connection. The fabrication of these components uses innovative process steps developed through research in this work. Results of the mechanical characteristics of these devices, and of the performance under environmental testing are presented. These demonstrate that this fibre interconnection technique offers significant benefits over the current methods and that the technique meets the required environmental specifications for telecommunications components. In summary, this thesis is a description of the development of the fibre attach technique and the integration of a complete process. The research is brought to the stage where all of the steps of the complete process have been tested in practice. The results of these tests, and the results of testing working devices based on the process are presented.
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Childs, David John. „British tanks 1915-18 : manufacture and employment“. Thesis, University of Glasgow, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309487.
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