In this study, a two axes linear positioning system for testing and applying different rapid prototyping techniques was designed and manufactured. A cable/ pulley mechanism is utilized in the system for transmitting motion from motors into linear motion. Use of a cable/ pulley mechanism overcomes the problems resulting from the utilization of conventional drive systems like ball screws and decreases the overall cost of the system. The carriage elements of both axes were designed and manufactured by using investment casting. The molds used in casting were also designed and manufactured within this study. The designed system is controlled by a servo motion control system composed of a motion controller, DC servo motors and linear encoders. All elements of the motion control system were selected, integrated and programmed within the scope of the study.

To reduce electronics packaging lead time and potentially to reduce manufacturing cost, an innovative packaging process targeting rapid package prototyping (RPP) has been developed. The developed RPP process, which is based on a data-driven chip-first approach, provides electrical functionality as well as form factors for micro-systems packages. The key component of the RPP process is the nano-particle silver (NPS) interconnect. However, NPS has not yet been adequately proven for use in electronics packaging applications. Moreover, its adhesion to electronics packaging materials such as polyimide, benzocyclobutene (BCB), copper, and aluminum is found to be weak. Thus, improving the adhesion strength of NPS will be a key issue for reliable package prototypes with NPS interconnects. In this research, the adhesion of NPS to substrate materials is found to be attributed to particle adhesion and more specifically, van der Waals forces. An adhesion model based on the van der Waals force is suggested in order to predict NPS adhesion strength to packaging materials. A new adhesion test method that is based on a die shear test and a button shear test is developed to validate the NPS adhesion prediction model. The newly developed adhesion test method is generic in nature and can be extended to other thin films' adhesion tests. The NPS adhesion model provides a general and explicit relation between NPS tensile bond strength and adhesion factors such as substrate hardness, adhesion distance, van der Waals constant, and particle diameter. The NPS adhesion model is verified as a first order adhesion model using experimental data from seventeen packaging materials. Substrate hardness is identified as a primary factor in NPS adhesion. Adhesion distance and van der Waals constant are also significant in organic and inorganic materials. Diffusion or other interfacial reaction between NPS and metal substrates such as copper and silver seems to exist. Finally, guidelines to improve the adhesion strength of NPS are suggested based on the adhesion model and on external adhesion factors such as Silane coupling agents and plasma treatment.

Indirect additive processing of ferrous metals offers the potential to freeform fabricate parts with good surface finish and minimal dimensional variation from the computer solid model. The approach described here is to mix a ferrous powder with a transient binder followed by selective laser sintering (SLS) in a commercial polymer machine to create a “green” part. This part is post-processed to burn off the transient binder and to infiltrate the porous structure with a lower melting point metal/alloy. Commercially available SLSed ferrous components contain copper-based infiltrant in a ferrous preform. The choice of copper alloy infiltrant has led to inferior mechanical properties of these components limiting their use in many non-injection-molding structural applications, particularly at elevated temperature. In the present work, an attempt has been made to replace the copper-based infiltrant considering cast iron as a potential infiltrant because of its fluidity, hardness and stability at comparatively high temperature. A critical consideration is loss of part structural integrity by over-melting after infiltration as chemical diffusion of alloying elements, principally carbon, occurs resulting in a decrease in the melting temperature of tool steel preform. A predictive model was developed which defines the degree of success for infiltration based on final part geometry and depending on the relative density of the preform and infiltration temperature. The processing regime is defined as a function of controllable process parameters. An experimental program was undertaken using commercially available LaserForm[superscript tm] A6 tool steel that was infiltrated with ASTM A532 white cast iron. Guided by Ashby densification maps, pre-sintering of the A6 tool steel SLS part was performed to increase the part initial relative density prior to infiltration. The final infiltrated parts were analyzed for geometry, microstructure and hardness. The model may be extended to other ferrous powder and infiltrant compositions in an effort to optimize the properties and utility of the final infiltrated part. / text

Professors need alternative programs to support their online teaching. This dissertation reports an initial study in a long-term research agenda for developing a faculty online teaching solution. The primary purpose of the study is to explore faculty perceptions of a case library to help decision makers and researchers determine whether they would pursue the use of such a tool to support faculty online teaching. The secondary purpose of the study is to generate design knowledge to inform future development of and research on this or similar case libraries. The methodology of this study includes three components: development research, rapid prototyping, and qualitative methods. Development research and rapid prototyping provided a three-stage framework for this study: conceptualization, development, and research. I synthesized the literature to create conceptual models of an Online Teaching Case Library (OTCL) at the conceptualization stage, built a prototype to implement the models at the development stage, and conducted research to evaluate the prototype at the research stage. Qualitative methods guided data gathering and analysis. I recruited seven faculty participants based on a purposeful sampling technique. To gather the data, I followed a three-step data collection process: initial interviews, contextual interviews, and final interviews. This process allowed me to observe and interview faculty participants while they were exploring the prototype. I analyzed the data by following an 11-step procedure synthesized from the works of Miles and Huberman (1994) as well as LeCompte and Schensul (1999a). This study found that on one hand, faculty members might use an OTCL, because they perceived that this tool could support their apprenticeship approach to learning to teach. On the other hand, however, their perceived decision to use an OTCL would also be influenced by the perceptions of the usefulness and usability of the tool. The study identified the initial evidence supporting an OTCL as an online teaching resource and the challenges involved in developing and implementing such a solution. It provides a base for decision makers to determine whether they would adopt this tool. It also offers some design guidance for those who do want to pursue this solution to faculty development.

No description available.

Vast amounts of evolving data are created in the design of hard real-time software systems. This data must be managed so that it can be stored and retrieved according to the needs of design engineers. In the Computer-Aided Prototyping System (CAPS), a Design Database (DDB) must manage the storage and retrieval of the entire Prototype System Description Language (PSDL) program. This thesis presents a conceptual design and initial implementation of a Design Database (DDB) for the Computer-Aided Prototyping System (CAPS).

Low-density cellular materials, metallic bodies with gaseous voids, are a unique class of materials that are characterized by their high strength, low mass, good energy absorption characteristics, and good thermal and acoustic insulation properties. In an effort to take advantage of this entire suite of positive mechanical traits, designers are tailoring the cellular mesostructure for multiple design objectives. Unfortunately, existing cellular material manufacturing technologies limit the design space as they are limited to certain part mesostructure, material type, and macrostructure. The opportunity that exists to improve the design of existing products, and the ability to reap the benefits of cellular materials in new applications is the driving force behind this research. As such, the primary research goal of this work is to design, embody, and analyze a manufacturing process that provides a designer the ability to specify the material type, material composition, void morphology, and mesostructure topology for any conceivable part geometry. The accomplishment of this goal is achieved in three phases of research: Design Following a systematic design process and a rigorous selection exercise, a layer-based additive manufacturing process is designed that is capable of meeting the unique requirements of fabricating cellular material geometry. Specifically, metal parts of designed mesostructure are fabricated via three-dimensional printing of metal oxide ceramic powder followed by post-processing in a reducing atmosphere. Embodiment The primary research hypothesis is verified through the use of the designed manufacturing process chain to successfully realize metal parts of designed mesostructure. Modeling & Evaluation The designed manufacturing process is modeled in this final research phase so as to increase understanding of experimental results and to establish a foundation for future analytical modeling research. In addition to an analysis of the physics of primitive creation and an investigation of failure modes during the layered fabrication of thin trusses, build time and cost models are presented in order to verify claims of the process s economic benefits. The main contribution of this research is the embodiment of a novel manner for realizing metal parts of designed mesostructure.

[Truncated abstract] Virtual sculpting is an interactive 3D modeling process that allows users to create and modify solid objects in a virtual world, with applications in art, rapid proto- typing and design. This thesis investigates methods for a collaborative, voxel-based virtual sculpting with haptic force-feedback. The objective is to devise such a system that operates in real-time. I make three main contributions in the fields of voxel-based virtual sculpting, haptics and collaborative virtual environments. First, I have devised a method for virtual sculpting where a voxel-based sculpture is created using a tool to build up or erode material. In existing real-time systems, due to the complexity of the algorithms that determine which voxels have been touched by the tool in a given time-step, the size or shape of the sculpting tool is limited and can often only be applied at a fixed orientation. My solution allows the tool to take the shape of any arbitrary triangle-based polyhedron that can be applied at any orientation. To determine which voxels are intersected by the tool, the tool is voxelized (converted into its discrete voxel representation) at each time-step against the voxels of the sculpture, which are then modified according to the desired operation. To give the resulting voxel-based sculpture a realistic appearance, I use the well-known Marching Cubes algorithm to form a triangular- mesh isosurface where the voxels representing sculpture material meet free-space. '...' For this I have borrowed concepts from the existing Voxmap-PointShell (VPS) model where the tool is represented by an array of points that cover its surface, each of which is tested for collisions with the sculpture. Each colliding point will form a component force, and the overall collision force is the vector sum of these components. My model is unique in that the component forces are formed in a direction tangential to the isosurface nearest the voxel of collision and can operate while the voxels of the sculpture are changing. While the VPS model is designed for force-feedback on a 6- degrees-of-freedom haptic device (delivers translational and rotational forces to the user), my model is designed to suit commodity 3-degrees-of-freedom (translational forces only) devices which are much more common. Third, I have developed a collaborative virtual sculpting paradigm to allow several users to simultaneously work on the same sculpture from different locations. This allows collaborative design without the requirement of being co-present. I will discuss methods for relaying the rapidly changing voxel and isosurface data between workstations, such that the local environment on each is synchronized in a manner that is immediate and transparent to the users. In addition, collisions between the different users' tools are felt through force-feedback. I implemented a collaborative haptic virtual sculpting simulation using the above methods in order to validate the system. The simulation was used to test the capabilities and limits of each contribution, as well as the real-time capability of the overall system. Ultimately this thesis demonstrates that it is possible to combine these technologies to form a flexible and intuitive collaborative virtual sculpting experience that operates in real-time.

Techn. Universiẗat, Diss., 2006--Darmstadt.

Thesis (MScEng (Industrial Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: As part of a growing trend in the medical industry of patient specific solutions, a need arises for means and methods that could grant surgeons the ability to improve their pre-operative planning, and help streamline their intra-operative proceedings relative to each individual patient. A suitable solution has emerged in the form of Additive Fabrication. Most of the traditional layer manufacturing technologies have been considered to be too expensive for medical application, and could not always be justified. However, more cost effective technologies, such as 3D Printing, have recently come to the scene and definitely require a fresh re-consideration for medical applications. In this report the research results are presented that look at the applications of 3D Printing in various fields of reconstructive surgery. Based on a variety of case studies the outcome strongly suggests that 3D Printing might become part of standard protocol in medical practice in the near future. / AFRIKAANSE OPSOMMING: Tans beweeg die mediese veld al hoe meer in die rigting van pasiënt uniekheid. Dit beteken dat behandeling begin weg beweeg van standaard prosedures en soveel moontlik aagepas word om aan te pas by elke unieke pasiënt. As deel hiervan ontstaan die behoefte by chirurge om hul operasies ook beter te beplan spesifiek tot elke individu, en sodoende te verseker dat die prosedures in teater so glad moontlik verloop. Daar is reeds tegnologië in die vorm van Addidatiewe Vervaardiging wat hierdie probleem aanspreek. Tot op hede was die finansiële implikasies vir meeste van die onderskeie tegnologië ‘n struikelblok wanneer dit kom by mediese toepassings. Tog, danksy meer koste effektiewe tegnologie soos 3D Drukwerk, is dit die moeite werd om weer op nuut te kyk na die moontlikhede wat die tegnologie kan bied. In hierdie verslag word daar gekyk na die verskillende toepassings van 3D Drukwerk in die veld van rekonstruktiewe chirurgie. Op grond van die resultate verkry vanaf ‘n wye verskeidenheid gevalle studies word die gevolgtrekking gemaak dat bekostigbare tegnologie soos 3D Drukwerk ‘n baie goeie kans het om in die nabye toekoms deel te word van standaard prosedure in die mediese praktyk.