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

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.

ABSTRACT EVALUATION OF FIT FOR 3D PRINTED RETAINERS AS COMPARED TO THERMOFORM RETAINERS By David Cole, D.M.D. A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Dentistry at Virginia Commonwealth University Thesis Directors: Eser Tüfekçi, D.D.S., M.S., Ph.D., M.S.H.A. Professor, Department of Orthodontics Sompop Bencharit, D.D.S., M.S., Ph.D. Associate Professor and Director of Digital Dentistry, Department of General Practice Introduction: Despite recent advances in three-dimensional (3D) printing, little information is available on 3D printed retainers Methods: Three reference models were used to fabricate traditional vacuum formed, commercially-available vacuum formed, and 3D printed retainers. For each model, three retainers were made using the three methods (a total of 27 retainers). To determine the trueness, the distances between the intaglio surface of the retainers and the occlusal surface of the reference models were measured using an engineering software. A small difference was indicative of a good fit. Results: Average differences of the traditional vacuum formed retainers ranged from 0.10 to 0.20mm. The commercially-available and 3D printed retainers had a range of 0.10 to 0.30mm and 0.10 to 0.40mm, respectively. Conclusions: The traditional vacuum formed retainers showed the least amount of deviation from the original reference models while the 3D printed retainers showed the greatest deviation.

Plastic is widely used to shape many of the daily goods produced and consumed today. Compared to wood and metal, this versatile material was recently introduced to society. The technical advances that began in the mid 1850's led to the invention of the first cellulose plastic polymers - a naturally occurring or synthetic compound consisting of large molecules made up of a linked series of repeated simple monomer (One Look on line Dictionary, 2009) - to be used at an industrial level. Inaugurating a period in which objects could have the strength of metal or wood, while also being lighter, colorful and cheaper to be manufactured. Plastics are a material that has the ability to be easily shaped (Lefteri, 2008). For me, plastic is ideal to work with, not only because its eclectic applications in product design and manufacture, but also due to its ordinary use in our globalized society. My master's research is to design functional objects using different types of plastics. My goal is to experiment with this material and understand the industrial production process behind the manufacture of the daily functional objects that surround us. Each plastic polymer has its proper usage and constraints. These characteristics are taken into account in my design process. Conceptually I allow myself to have freedom in exploring the object's form by respecting the material`s limitations as well as the techniques I have available to design and make my pieces. In conjunction with this creative research, I am using Computer Aided Design and Computer Aided Manufacturing through Computer Numerical Control and Rapid Prototyping technologies to design and produce the pieces. Furthermore, my intention is to have a deep understanding of the uses, production, discard and, recycling procedures of plastics goods. I am interested in knowing more about biodegradable, compostable and recyclable polymers in order to enjoy this great material that is evolving rapidly (Lefteri, 2008) in the contemporary society without causing environmental damage and preserve good conditions to future habitants of the Planet.

Support materials play a vital role across the entire field of additive manufacturing (AM) technologies. They are essential to provide the ability to create complex structures and features using AM. Successful implementation of support materials in ultrasonic consolidation (UC) will provide a vast opportunity for improvement of geometric complexity. Experimentation was performed to evaluate suitable support materials and their effectiveness within UC. Additionally a fused deposition modeling (FDM) system was integrated into the UC build environment to create an automated support deposition system. Finally several unique structures were built using support materials to demonstrate the improved geometric capability and to develop design rules for use in UC.

In this study, a previously designed passive dynamic walker (PDW) is built out of aluminum and plastic. The aim of the study was to produce an asymmetrical PDW and to compare the results to a computer simulation to validate the mathematical model. It also aimed at identifying the limitations of using additive manufacturing to create components for a PDW as well as gain insights on asymmetric systems. Beginning with a five mass kneed model, parameters were varied to produce up to a nine mass kneed model solution. The nine mass model allows more variability in added mass locations and separates the zeroth, first, and second moments of inertia. To validate asymmetric gait, step length and step time of the prototype were compared to the simulation. The walker, unable to produce a steady gait, failed to match the asymmetric simulation. More than four times the amount of symmetric data was found compared to asymmetric data. Successful runs of symmetric gaits were approximately double than for asymmetric gaits. The reason for unequal successes is thought to be due to greater instability of asymmetric systems. This instability is thought to be due to inertia from a constant state of hanging motion. 3D printing proved useful in simplifying components and reducing waste but the polymers used did not have enough strength when mass was added to the system. Joining differing materials on the legs was difficult to keep in place. A smaller more robust design could solve these problems. This study focused on understanding physically asymmetric PDWs. These simple robots separate the neurological and mechanical controls of walking and are advantageous for studying physical parameters of human gait. Once a reliable asymmetric walker is built, further research could alter the foot shape or knee location to reverse the process, thus having a PDW walk symmetric. Once a walker is successfully reverted from walking asymmetrical to symmetrical, these parameters could be then applied to human subjects. An example of this would be for prosthetic foot design.

<p>Matlab Simulink is a commonly used tool in the design process of control systems. To further take advantage of the Matlab Simulink models it is desirable to translate them for realtime use together with the possibility to read/write physical signals. </p><p>Real-Time Workshop is an extension to Simulink that automatically generates code from a model to a variety of target platforms. RTAI and RTLinux are hard realtime operating systems, making use of Linux. </p><p>To make automatically generated code run on RTAI and RTLinux an adaptation of the generation of code is necessary. </p><p>To control, for example, an automotive engine a data acquisition card with an appropriate device driver is required. Comedi, an open source project, provides a number of device drivers for data acquisition cards. </p><p>The developed system makes use of Simulink, Real-Time Workshop, RTAI or RTLinux, and the standard data acquisition card NI 6035E using a Comedi device driver. The Simulink models may be executed at frequencies up to 50 kHz on ordinary PC hardware. </p><p>The evaluation of the system consisted of measuring the interrupt latency of the used motherboard's bus, measuring computation times running Simulink models with known complexity, running models developed at Vehicular Systems and a comparison of interfacing Simulink/Real-Time Workshop between RTAI and RTLinux. </p><p>The recommended realtime operating system is RTAI due to the open source community support of it as a target platform for Real-Time Workshop.</p>

This paper introduces an alternative technique for the development of microfluidic systems for biotechnology based on mechanical machining and ultrasonic welding. Advantages of this approach over existing prototyping approaches involving the rapid development of tooling include: (a) short cycle time, (b) design flexibility, and (c) low cost manufacturing. In addition, the process provides a migration path to high volume production. A limitation of this system is that it cannot practically produce microchannels smaller than about 250 μm (0.010 in). However, for many biological cell-based biosensors, this feature scale seems well suited based on cell viability results. Several issues are discussed relevant to this approach, including bond strength, seal leakage, and sterilization. / Graduation date: 2002

An algorithm was developed to enable efficient segmentation of dimensionally-large objects into smaller components that can be fabricated within the given Rapid Prototyping (RP) machine workspace. The algorithm uses vertical and horizontal flat plane cuts, as well as feature-based volume decomposition. Due considerations were given to the optimisation of the surface accuracy, the build time, the strength and the number of segments generated by the segmentation process. A computer-aided design (CAD) application programme that interfaces with Unigraphics (UG) was also developed to allow import of objects in Standard Triangulated Language (STL) files into UG without loss of accuracy. In addition, the application software provides the functions that facilitate the implementation of the segmentation algorithm in UG. Two case studies were carried out using the algorithm in a Selective Laser Sintering (SLS) RP system. The resulting objects had properties that matched the research objectives with which the proposed algorithm was validated. / Singapore-MIT Alliance (SMA)

The purpose of this study was to investigate the implications of additive manufacturing on industrial design profession and designers through an explorative study. Through a literature survey, implications of additive manufacturing technologies on industrial designers and industrial design profession were explored. Expanding literature survey with on-line searches, several experimental and commercial application examples of rapid manufacturing of products were identified. These identified examples were then used for a qualitative evaluation on the implications of additive manufacturing for the industrial design profession and designers through semi-structured interviews conducted with seven professional industrial designers having experience with rapid manufacturing in Istanbul Turkey. The research concluded with significant implications of additive manufacturing having the potential to cause paradigm shifts in industrial designer&rsquo / s role, definition of the profession and design process. The conclusions derived include suggestions to exploit the potential brought by these technologies and their applications.