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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.
141

Adaptive process planning of rapid prototyping and manufacturing for complex biomedical models

Jin, G. January 2012 (has links)
In this research, a set of novel, integrated and systematic adaptive process planning algorithms and strategies, which include adaptive tool-path generation algorithms and strategies, adaptive slicing algorithms and strategies, adaptive approach for FGM(Functionally Graded Material)-based biomedical model and build time and geometrical accuracy analysis and control modules, for complex biomedical model fabrication in the RP/M (Rapid Prototyping and Manufacturing) process, have been developed to balance and optimise the geometrical accuracy and build efficiency. In the developed adaptive tool-path generation algorithms and strategies, directly slicing algorithm and NURBS(Non-Uniform Rational B-Spline)-based curves have been developed to represent the boundary contours of the sliced layers to maintain the geometrical accuracy of original biomedical models. The developed mixed tool-path generation algorithm can be used to generate mixed contour and zigzag tool-paths to preserve geometrical accuracy and speed up fabrication. Based on the developed build time and geometrical accuracy analysis modules, the developed adaptive speed algorithms can be used to further reduce build time of biomedical model fabrication in RP/M. In the developed adaptive slicing approach, rotating slicing and two thresholds have been introduced to extract surface feature of biomedical models. Then, an adaptive slicing thickness determination algorithm has been developed to decide the thickness of each slicing layer based on the outside surface complexity of the model. In addition, the user can balance the geometrical accuracy and the build efficiency during RP/M processing with the different values of two pre-setting thresholds. Furthermore, by choosing the right value of the pre-setting thresholds, it can also effectively reduce the build time and improve the accuracy of biomedical model fabrication in RP/M. In the developed adaptive approach for FGM-based biomedical model fabrication, FGM-based modelling features can represents typical FGM-based biomedical models effectively, and the linear and non-linear control parameters for FGM composition and distributions can enable users to address their specific functional needs of FGM-based biomedical model. The proposed mixed tool-path generation algorithm and adaptive speed algorithm can be used to generate a series of contour/offset tool-paths to represent the material gradual change, and zigzag tool-path is generated for the internal area of a single material to support the realizable and customized FGM-based biomedical models fabrication in RP/M efficiently.
142

Modeling and process planning for exposure controlled projection lithography

Jariwala, Amit Shashikant 02 April 2013 (has links)
A novel approach to microfabrication based on stereolithography was presented. This fabrication process is referred to as, ‘Exposure Controlled Projection Lithography’ (ECPL). In the ECPL process, incident radiation, patterned by a dynamic mask, passes through a transparent substrate to cure photopolymer resin. By controlling the amount of exposure, the height field of the cured film can be controlled. An ECPL system was designed and assembled. Factors affecting the accuracy of the ECPL process in fabricating micron shaped features were identified and studied. A real-time in-situ photopolymerization monitoring system was designed and assembled within the ECPL system to identify the sources of variations present in the system. Parts are fabricated from the ECPL process because of polymerization (or cross-linking) of monomer resin using light energy. Photopolymerization is a complex process involving coupling between several phenomena. This process was modeled by utilizing an understanding of the known polymerization reaction kinetics with incorporating the effects of oxygen inhibition and diffusion. A material response model and a simulation tool to estimate the shape of a cured part resulting from photopolymerization was created. This model was used to formulate a process-planning method to estimate the manufacturing process inputs required to cure a part of desired shape and dimensions. The process planning method was validated through simulations and experiments.
143

Advances in the Development of Missile Telemetry Test Sets: Utilizing 3D Printing for Rapid Prototyping and Manufacturing

Apalboym, Maxim, Kujiraoka, Scott 10 1900 (has links)
ITC/USA 2015 Conference Proceedings / The Fifty-First Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2015 / Bally's Hotel & Convention Center, Las Vegas, NV / Functionally testing missiles in the All Up Round (AUR), a configuration that consists of a complete system packaged in its flight worthy state, requires the use of test sets along with constituent conformal equipment for interfacing. During developmental testing, telemetry (TM) sections are integrated within an AUR missile. These test sets monitor TM unit performance while maintaining form, fit, and function; therefore, resulting in complete data confidence. Initiating TM functional tests permit a capability in verifying that TM sections have been integrated properly. Safety being a priority, in order to attenuate RF radiation leakage while providing repeatable test capabilities in the near-field, antenna couplers are fabricated as a shielding interface between the user and radiating source and a coupling interface between an AUR missile and the test set. Generally, antenna couplers are composed of metallic bodies which require machine shop fabrication. The process of getting machined parts can take up to several months which can delay delivery schedules. With the availability of 3D printing capabilities and methods in metalizing various materials, a novel approach to fabricating antenna couplers has been explored. The use of modeling Software Packages (Computer Aided Design and Electromagnetic Solvers) and additive printing play key roles in reducing the development cycle time while saving costs, decreasing weight, and sustaining performance. This paper will detail the efforts using 3D printing capabilities in the development and fabrication of an antenna coupler with several examples cited herein.
144

Implementation of a language translator for the computer aided prototyping system

Altizer, Charles Edwin 12 1900 (has links)
Approved for public release; distribution is unlimited / Rapid prototyping is a method of software system development that is gaining much support presently. Rapid prototyping allows the designer to quickly produce a model of a system or part of a system which the user can see and thus verify if his requirements have been met. The prototype specifications can then be efficiently converted to an accurate set of program specifications that the programmers can implement as a final working system. The computer aided prototyping system (CAPS) is a rapid prototyping system that will automate many of the processes of prototyping such as code generation of prototype modules and searching for reusable components. One of the many components of CAPS is a language translator which translates a prototype specification written in the Prototype System Description Language (PSDL) into a set of Ada procedures and packages. The Ada procedures and packages, when executed in proper order, will effectively execute the prototype. This thesis demonstrates an implementation of the translator component of the CAPS. An attribute grammar tool, Kodiyak, is used to build a translator which implements the major constructs of PSDL and produces Ada code to implement PSDL operators according to their control constraints. / http://archive.org/details/implementationof00alti / Lieutenant, United States Navy
145

Lead-time reduction and rapid prototyping of tools and fixtures, therefore I AM : A case study about additive manufacturing in the automotive industry

Gustafsson, Christopher January 2019 (has links)
The purpose of this thesis is to investigate how to decrease lead-times of conventionally manufactured prototypes of tools and fixtures. Which could lead to increased knowledge of how an operations site within the automotive industry could utilize additive manufacturing when producing company specific prototypes of tools and fixtures.  The research approach applied in this case study combines a literature review to systematically find relevant literature aligned with the research topic of additive manufacturing or 3D printing related to lead-time reduction and generative design terms. With the help of interviews and observations profound knowledge was gained as preparation before continuing the research. Thereafter, a pre-study was conducted in order to further enhance the understanding of the industrial context of the two chosen fixtures (study objects). Rapid prototyping activities with additive manufacturing processes and technologies of experimentation character was conducted iteratively with both 3D CAD and 3D printing software and hardware. Analysis of the data was conducted through a comparison between lead-times of conventionally manufactured and 3D printed prototypes of the two chosen fixtures. Moreover, identifying potential effects with additive manufacturing of prototypes have with a SWOT analysis.  The case study found that additive manufacturing could significantly decrease lead-times when producing prototypes compared to conventional manufacturing. Furthermore, the results showed that the effects of additive manufacturing are plenty and rather complex due to the fact of this new way to manufacture prototypes. Therefore, the term design for additive manufacturing need first class priority if next steps were to be taken in the additive manufacturing field to enhance industrial and academic benefits.  The research on this subject is strongly constrained by the scarcity of empirical experience and, consequently, by the scarcity of available empirical data. Research publication on the topic are fruitful and plenty but their findings specified to their chosen study objects. This case study gives an up-to-date contribution to the topic of additive manufacturing with endless possibilities to reduce lead-time with rapid prototyping activities that utilizes additive manufacturing. Moreover, the research approach used in this thesis combines 3D CAD data through theoretical concepts and physical objects with additive manufacturing practice. Overall, the results can be used to improve academic research in the topic and promote discussion among different actors entering or within the additive manufacturing field.
146

Prototipagem rápida e ferramental rápido aplicados às peças utilizadas em ensaios estáticos de embalagens para acondicionamento e transporte de peças automotivas. / Rapid prototyping and rapid tooling applied parts used in in static tests of racks for packaging and transporting automobile parts.

Silva, Guilherme Canuto da 25 September 2008 (has links)
A necessidade deste trabalho se fez no setor de Planejamento de Fluxo de Materiais e Embalagens (PFME), que pertence ao departamento de engenharia de manufatura de uma filial de montadora instalada no Brasil. Neste setor existe a necessidade de se obter peças protótipo em um menor espaço de tempo possível para realização dos ensaios estáticos dos protótipos das embalagens especiais, uma vez que as embalagens precisam acondicionar as peças produzidas a partir da fase de preparação da produção em série do automóvel (pré-série ou PVS). Neste trabalho, a partir do estudo das tecnologias de Rapid Prototyping (RP) - Prototipagem Rápida (RP) e Rapid Tooling (RT) Ferramental Rápido (RT) é selecionada a técnica mais adequada para se atender às necessidades deste setor. Para isto, algumas condições de contorno foram consideradas: a aplicação das técnicas de RP e RT foram restringidas às peças externas do carro como portas, tampas dianteiras, traseiras e pára-lama e as fontes fornecedoras consultadas encontram-se no mercado doméstico. Com base em um estudo de caso pode-se validar esta proposta. Os resultados obtidos com a aplicação da técnica de ferramental rápido Vacuum Bagging foram uma redução média de 4,5 meses na obtenção das peças protótipo e uma redução global dos custos de aquisição de aproximadamente R$ 100.000,00. / The need of this work was made in the material flow planning and packing (PFME) section, that belongs to the manufacture engineering department of an assembler company installed in Brazil. In this sector, there is a growing need to obtain prototype parts in the shortest time possible in order to carry out static prototype tests of the special packing, since these racks need to be ready to assist the preparation phase of the series production of the vehicle (pre series or PVS). In this work, beginning from the study of Rapid Prototyping (RP) and Rapid Tooling (RT) technologies is selected the technique more adequate to assist to the needs of this section. For that purpose, some limiting conditions were considered: the application of the RP and RT techniques is limited to the external parts of the vehicle, such as doors, front and back hoods and fenders, and the consulted suppliers should be available in the domestic market. Based in a case study this proposal could be validated. The obtained results with the applied Rapid Tooling Vacuum Bagging technique were a medium reduction of 4,5 months in the prototype parts acquisition and a global reduction in the acquisition costs of approximately R$ 100.000,00.
147

"Manufatura rápida - avaliação das tecnologias de impressão 3D e FDM na fabricação de moldes rápidos" / Rapid Manufactory – Comparative evaluations of 3D printing system against FDM system for Rapid Tooling

Martins, José Roberto 16 May 2006 (has links)
Este trabalho avaliou a aplicação das tecnologias de prototipagem rápida por Impressão 3D e FDM (Fused Deposition Modeling) na produção de moldes rápidos. Esta avaliação foi feita com base nas qualidades das peças obtidas por vazamento nos moldes produzidos, bem como nas limitações encontradas em suas utilizações. Foram estabelecidas as principais diferenças do ponto de vista de qualidade, custos, tempos gastos e praticidade. Foram construídos moldes para peças que contemplando vários graus de dificuldades. Para cada ferramental foram obtidos lotes de peças, através dos quais foram analisadas e comparadas as qualidades dos protótipos. / This work evaluated the application of the Rapid Prototyping technologies 3D printer and FDM (Fused Deposition Modeling) in the rapid manufacturing of molds. This evaluation is based on the quality of the parts molded, as well as in the limitations found in the molds applications. As result the main differences related to quality, and usability was established. The molds produced parts with different degrees of geometric difficulties. For each mold, a few prototypes were produced and their qualities compared.
148

Modelamento médico: uma integração entre CAD, CAE, engenharia reversa e prototipagem rápida / Medical modeling: an integration among CAD, CAE, reverse engineering and rapid prototyping

Coelho, Marco Antonio Oliveira 29 April 2003 (has links)
Modelamento médico é uma técnica utilizada por cirurgiões no auxílio da diagnose, comunicação com o paciente, estudos pré-operatórios, definição e simulação de procedimentos cirúrgicos, visando diminuir o tempo cirúrgico e de convalescença do paciente. Em aplicações mais recentes, esta técnica tem sido utilizada no desenvolvimento de próteses personalizadas, possibilitando que reconstituições de grande complexidade sejam feitas de maneira rápida e segura. Resumidamente, a técnica consiste em produzir um protótipo em terceira dimensão do tecido ou deformidade em estudo. Utiliza-se hoje de modernas tecnologias como tomografia computadorizada e prototipagem rápida entre outras, representando um exemplo significativo de integração entre diferentes áreas do conhecimento. Este trabalho apresenta e discute o modelamento médico no que se refere às suas aplicações, enfocando a integração entre as tecnologias de prototipagem rápida, engenharia reversa (RE) e projeto e engenharia assistidos por computador (CAD/CAE). É feita uma descrição dos procedimentos de geração dos modelos médicos usando técnicas de prototipagem rápida a partir de dados obtidos de tomografia computadorizada, e um estudo de sua precisão dimensional e geométrica. São explorados os recursos possibilitados pela integração com sistemas CAD/CAE, e apresentadas aplicações reais das técnicas na área de cirurgias craniofaciais, evidenciando as vantagens de sua utilização e validando os procedimentos propostos. / Medical modeling is a technique used by surgeons in the diagnosis, communication with the patient, preoperative studies, definition and simulation of surgical procedures. It helps to reduce the operative and convalescence time. It consists of producing a prototype in third dimension of the tissue or deformity in study. In some more recent applications, this technique has been used to develop customized prosthesis, enabling that quite complex reconstructions can be made in a safe and fast way. Nowadays, it uses modern technologies as the computer tomography and rapid prototyping, and it represents significant example of integration among different areas of the knowledge. This work presents the medical modeling and discusses its applications, with emphasis in the integration of the technologies of rapid prototyping, reverse engineering (RE) and computer aided design and engineering (CAD/CAE). It is made a description of the procedures to generate the medical models using rapid prototyping techniques starting from computer tomography data, and a study regarding the dimensional and geometric precision of the medical models generated by rapid prototyping. The advantages of the integration with CAD/CAE technologies are shown and a case study is developed aiming to validate the proposed procedures.
149

Algorithms for layered manufacturing in image space. / CUHK electronic theses & dissertations collection

January 2013 (has links)
Layered manufacturing plays important role in industry. Conventional pro-cess planning takes polygon soup as input and has high quality requirements on these polygonal model such as no self-intersection, no degenerate polygon et al. A growing number of models, especially for those in complex shape are acquired from reverse engineering. Implicit representation always serves as intermediate representation and ¯nally need to be tesselated into polygonal mesh for layered manufacturing applications. However, the present tessellation techniques have difficulties to provide topologically faithful and self-intersection free polygonal mesh from implicit model. On the other hand, implicit representation are mathematically compact and robust, which is important for presenting complex freeform models. / I develop a robust and efficient approach to directly slicing implicit solids. Different from prior slicing techniques that reconstruct contours on the slicing plane by tracing the topology of intersected line segments, which is actually not robust, I generate contours through a topology guaranteed contour extraction on binary images sampled from given solids and a subsequent contour simplification algorithm which has the topology preserved and the geometric error controlled. The resultant contours are free of self-intersection, topologically faithful to the given r-regular solids and with shape error bounded; therefore, correct objects can be fabricated from them by layered manufacturing. Moreover, since I do not need to generate the tessellated B-rep of given solids, my direct slicing approach is memory efficient - only the binary image and the finest contours on one particular slicing plane need to be stored in-core. My method is general and can be applied to any implicit representations of solids. / Moreover, I also investigate techniques for support generation for layered manufacturing in image space. Region subtraction is a crucial operation for support generation. I develop a robust and reliable region subtraction method on implicit solid slicing. Compared with the conventional approach in which support regioncontours are produced from part slicing contours by polygonal operations, my approach calculates reasonable support region on binary image for each layer. I investigate a conservative growing-swallow technique to remove as much as possible the support material for self-support region while still guarantee the safety of building process. My region subtraction can serve as core technique for many layered manufacturing processes. In my research, I demonstrate region subtraction technique in both Fused Decomposition Modeling(FDM) and Stereolithography(SLA). A region cleaning technique which can reduce topology complexity of calculated support structure region is developed to fulfil specific requirement of FDM. With all the operations involved being discrete on binary image, my approach is more robust compared with the polygonal operations which are based on numerical computation. Moreover, processing on binary image makes my approach highly parallelizable. My self-intersection free contour extraction technique used in direct slicing can also be adopted to extract support structure contour on binary image if necessary. / Huang, Pu. / "October 2012." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 80-84). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract --- p.i / Chinese Abstract --- p.iii / Acknowledgements --- p.iv / List of Figures --- p.vii / List of Tables --- p.ix / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Contribution --- p.4 / Chapter 1.3 --- Organization --- p.5 / Chapter 2 --- Literature Review --- p.7 / Chapter 2.1 --- Direct Slicing on Implicit Solid --- p.7 / Chapter 2.2 --- Slicing based Support Generation --- p.9 / Chapter 3 --- Problem Definition --- p.10 / Chapter 4 --- Topologically Faithful Slicing Contour Generation --- p.12 / Chapter 4.1 --- Introduction --- p.12 / Chapter 4.2 --- Sampling and Contour Generation --- p.15 / Chapter 4.2.1 --- Sampling --- p.16 / Chapter 4.2.2 --- Topologically faithful contouring --- p.17 / Chapter 4.2.3 --- r-Regularity and Accuracy in Layered Manufacturing --- p.19 / Chapter 4.3 --- Constrained Smoothing --- p.20 / Chapter 4.4 --- Contour Simplification --- p.24 / Chapter 4.4.1 --- Variational segmentation --- p.25 / Chapter 4.4.2 --- Topology and distortion verification --- p.27 / Chapter 4.4.3 --- Hausdorff Error Analysis --- p.31 / Chapter 4.5 --- Results and Discussion --- p.33 / Chapter 5 --- Reliable and Robust Region Subtraction for Support Generation --- p.43 / Chapter 5.1 --- Introduction --- p.43 / Chapter 5.2 --- Preliminary --- p.46 / Chapter 5.3 --- Region Subtraction --- p.48 / Chapter 5.3.1 --- Binary Image Grid-width and Self-support Feature Threshold --- p.48 / Chapter 5.3.2 --- Conservative Growing-swallow Method --- p.50 / Chapter 5.4 --- Region Cleaning Technique for FDM --- p.53 / Chapter 5.5 --- Anchor Support Generation for SLA --- p.57 / Chapter 5.6 --- Result and Discussion --- p.60 / Chapter 6 --- Conclusion --- p.71 / Chapter 6.1 --- Summary and Discussion --- p.71 / Chapter 6.2 --- Future Work --- p.73 / Chapter A --- Inconsistent Contouring Problem Analysis --- p.76 / Bibliography --- p.80
150

O uso da prototipagem e fabricação digital no ambiente FAB LAB

Oliveira, Diego Jucá de Lima January 2016 (has links)
Até recentemente as novas tecnologias de fabricação digital só eram encontradas na indústria e em algumas universidades. Hoje essas tecnologias estão cada vez mais acessíveis e baratas e têm se consolidado como grandes aliadas no processo de projeto em áreas como Arquitetura, Design e Engenharia. Ambientes como os Fab Labs têm auxiliado o processo de desenvolvimento de produto e a realização de experimentações através da prototipagem rápida e da fabricação digital, oferecendo de forma aberta, suporte na utilização de um conjunto de ferramentas digitais. Dessa forma, buscou-se, como objetivo geral neste trabalho, evidenciar o potencial dos Fab Labs como ambientes para o uso da fabricação digital e da prototipagem rápida no processo de projeto. Como forma de atingir esse objetivo, foi realizada uma pesquisa qualitativa, através de estudo de caso e por meio de entrevista com gestores de três Fab Labs situados no Brasil. Inicialmente, foi feita uma abordagem sobre temas como prototipagem rápida e fabricação digital, buscando o esclarecimento do tema e a formação do corpo teórico. A pesquisa bibliográfica abordou temas como tipos de protótipos e a importância do ato de prototipar. Os resultados obtidos por intermédio das entrevistas e das observações, apresenta considerações importantes em relação ao conceito Fab Lab enquanto potencializador no desenvolvimento de projetos. / Until recently the new digital manufacturing technologies were only found in the industry and some universities. Today these technologies are increasingly affordable and cheap and have been established as major allies in the design process in areas such as Architecture, Design and Engineering. Environments such as Fab Labs have aided the product development process and performing trials through rapid prototyping and digital fabrication, providing an open, support the use of a set of digital tools. Thus, it sought to, the general objective of this study was to highlight the potential of Fab Labs as environments for the use of digital manufacturing and rapid prototyping in the design process. In order to achieve this goal, a qualitative survey was conducted through case study and through interviews with managers of three Fab Labs located in Brazil. Initially, an approach on issues such as rapid prototyping and digital manufacturing was made, seeking the theme of enlightenment and the formation of the theoretical body. The literature has addressed such topics as types of prototypes and the importance of prototyping act. The results obtained through the interviews and observations, presents important considerations regarding the concept Fab Lab while potentiating the development projects.

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