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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Digital data processing and computational design for large area maskless photopolymerization

Rudraraju, Anirudh V. 12 January 2015 (has links)
Large Area Maskless Photopolymerization (LAMP) is a novel additive manufacturing technology currently being developed at Georgia Tech in collaboration with the University of Michigan at Ann Arbor and PCC Airfoils. It is intended for the fabrication of integrally cored ceramic molds for the investment casting of precision components such as high-pressure turbine blades. This dissertation addresses the digital data processing and computational design needs for this technology. Several data processing schemes like direct slicing, STL slicing, post-processing schemes like error checking, part placement and tiling etc. were developed in order to enable the basic functionality of the LAMP process. A detailed overview of these schemes and their implementation details are given in this dissertation. Several computational schemes to improve the quality and accuracy of parts produced through the LAMP process were also implemented. These include a novel volume deviation based adaptive slicing method to adaptively slice native CAD models, a gray scaling and dithering approach to reduce stair stepping effect on downward facing surfaces and a preliminary experimental study to characterize the side curing behavior of the LAMP photo-curable suspension for pre-build image compensation. The implementation details and a discussion of the results obtained using these schemes are given. A novel approach for addressing the “floating island” problem encountered in additive manufacturing was also developed. The need for supports specific to the kind of parts being built through LAMP is evaluated and a support generation strategy different from the previously reported approaches in the literature is presented. Finally, a few novel film cooling schemes that are extremely challenging to fabricate using existing manufacturing technologies but possible to fabricate using LAMP are chosen and analyzed for their cooling performance. It is shown that such novel schemes perform much better in cooling the blade surface than the conventionally implemented schemes and hence this final component of work gives a better appreciation of the impact LAMP technology has in disrupting the state of the art in turbine blade manufacturing and truly taking the blade designs to the next level.
2

A Study of Digital RF Phase Shifters Fabricated With Additive Manufacturing

Vega, Yaniel 30 October 2015 (has links)
Digital RF phase shifters fabricated using additive manufacturing processes are presented and studied. The purpose is to explain the performance differences between phase shifters fabricated using additive manufacturing and those fabricated with conventional subtractive techniques. All phase shifters are designed to operate at a center frequency of 2.45 GHz with a 100 MHz bandwidth. The 1-bit 45° switched line phase shifters have an average insertion loss of 1.3 dB and a 220 mm2 footprint, while the 1-bit 180° high-pass low-pass phase shifters have an insertion loss 1.56 dB and a 180 mm2 footprint. The 4-bit high-pass low-pass, switched line hybrid phase shifters on the other hand show an average state insertion loss of 5.4 dB and have a 660 mm2 foot print. By carefully analyzing the performance of the various phase shifter designs it is shown that the limiting factors of additive manufacturing technology are the low conductivity of CB028 silver ink in comparison to copper, and the inability to print dielectrics with low surface roughness. Finally, parallel plate capacitors and a spiral inductor designed to be fabricated using additive manufacturing techniques are studied. This is done in order to better understand the advantages and disadvantages of such a design. By analyzing the component’s simulated performance it is shown that 3D printed capacitors and inductors are feasible as long as the capacitance or inductance values needed are low. Large value 3D printed components are impractical for RF applications due to their large size.
3

CUSTOMER DRIVEN SUPPLY CHAINS AND DIRECT DIGITAL MANUFACTURING TECHNOLOGY

MARTINELLI, ELISA MARTINA 28 March 2018 (has links)
Nel contesto della nuova rivoluzione industriale, alti livelli di turbolenza, dinamismo, volatilità, globalizzazione, competizione e un diverso ruolo del consumatore riconfigurano il panorama delle supply chain e delle innovazioni. Nonostante il valore co-creato e le ultime innovazioni in ottica customer driven siano ormai elementi imprescindibili, poche ricerche si sono focalizzate sulle caratteristiche di una supply chain guidata dal consumatore e sull’impatto o implementazione della stampa 3D. Pertanto, questa tesi mira ad esplorare gli aspetti principali della customer driven supply chain e della direct digital manufacturing technology. Il Paper I presenta una revisione sistematica della letteratura e fornisce un quadro concettuale utile per organizzare i contributi più recenti sull'argomento, implementando la teoria e suggerendo linee guida per i manager. Il Paper II e Paper III propongono ricerche qualitative mediante singoli casi studio che rispettivamente analizzano come la stampa 3D è in grado di facilitare la supply chain customer centricity attraverso la co-creazione di valore nel settore aerospaziale e come un technology provider può implementare un’innovazione customer centric nel settore della gioielleria italiana. Gli studi suggeriscono modelli concettuali e proposizioni che incrementano la letteratura esistente e guidano i manager. Questa tesi contribuisce all'esplorazione dei recenti progressi in merito all’'orientamento della supply chain e della direct digital manufacturing technology fornendo analisi critiche approfondite relative a diverse metodologie. / In the new industrial revolution, high levels of turbulence, dynamism, volatility, globalization, competition and modified customer’s role reconfigure supply chains and innovations landscape. Even if value co-creation and last technologies towards customer driven orientation are unavoidable elements, few contributions have focused on customer driven supply chain characteristics and on 3D printing impact on supply chain or elements of its implementation. For this reason, the thesis aims to explore the main features of customer driven supply chains and direct digital manufacturing technology. Paper I presents a systematic literature review that shows a conceptual framework able to organize the most recent contributions on the topic, implementing the knowledge on the theme and suggesting guidelines to managers. Paper II and Paper III provide qualitative constructive single case study research respectively focused on how 3D printing can enable supply chain customer centricity by value co-creation in the aerospace sector and how 3D printing can be implemented by a technology provider in the Italian jewellery sector. The studies suggest conceptual framework and propositions for improving existing knowledge and addressing managers. This thesis contributes to the exploration of recent advancements in supply chain orientation and direct digital manufacturing technology by providing deep critical analysis related to diverse methodologies.
4

The Design And Development Of An Additive Fabrication Process And Material Selection Tool

Palmer, Andrew 01 January 2009 (has links)
In the Manufacturing Industry there is a subset of technologies referred to as Rapid Technologies which are those technologies that create the ability to compress the time to market for new products under development . Of this subset, Additive Fabrication (AF), or more commonly known as Rapid Prototyping (RP), acquires much attention due to its unique and futuristic approach to the production of physical parts directly from 3D CAD data, CT or MRI scans, or data from laser scanning systems by utilizing various techniques to consecutively generate cross-sectional layers of a given thickness upon the previous layer to form 3D objects. While Rapid Prototyping is the most common name for the production technology it is also referred to as Additive Manufacturing, Layer Based Manufacturing, Direct Digital Manufacturing, Free-Form Fabrication, and 3-Dimensional Printing. With over 35 manufacturers of Additive Fabrication equipment in 2006 , the selection of an AF process and material for a specific application can become a significant task, especially for those with little or no technical experience with the technology and to add to this challenge, many of the various processes have multiple material options to select from . This research was carried out in order to design and construct a system that would allow a person, regardless of their level of technical knowledge, to quickly and easily filter through the large number of Additive Fabrication processes and their associated materials in order to find the most appropriate processes and material options to create physical reproductions of any part. The selection methodology used in this paper is a collection of assumptions and rules taken from the author's viewpoint of how, in real world terms, the selection process generally takes place between a consumer and a service provider. The methodology uses those assumptions in conjunction with a set of expert based rules to direct the user to a best set of qualifying processes and materials suited for their application based on as many or as few input fields the user may be able to complete.
5

Prospects for Sustainable Micro-Factory Retailing in Canada: A Case Study of 3D Printed Electric Vehicles

Hachey, Stephen Quinn January 2018 (has links)
The contemporary global automotive industry has persisted, relatively unchanged, since its inception over a century ago. However, it appears that major changes may be underfoot with increasing environmental, social, and economic pressures to improve the industry's long-term sustainability. An alternative model, known as Micro-Factory Retailing (MFR), guided by the emerging field of Industrial Ecology (IE) has been proposed as a possible solution to the industry’s sustainability crisis. This thesis will explore the prospects of MFR in Canada and propose the use of 3D printed electric vehicles as a means to facilitate sustainable system innovation. To demonstrate the feasibility of this proposed technological pathway, three entrepreneurial firms attempting to disrupt the way in which cars are made, sold, and used will be studied. Although the timeline of such a major transition is currently unknown, Canada should act proactively to transition its role in the global automotive sector and lead the way towards a more sustainable automotive ecosystem through MFR. / Thesis / Master of Science (MSc)

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