This diploma thesis deals with a new concept of maintenance and operation of production technologies, where spare parts are manufactured using rapid prototyping methods. The options are compared with currently used methods. Furthermore, methodological recommendations are written on how to proceed with the application. The aim of the work is to evaluate the concept and confirm the theoretical assumptions on a case study.

Indiana University-Purdue University Indianapolis (IUPUI) / Powder bed fusion (PBF) process is a metal additive manufacturing process, which can build parts with any complexity from a wide range of metallic materials. Research in the PBF process predominantly focuses on the impact of a few parameters on the ultimate properties of the printed part. The lack of a systematic approach to optimizing the process parameters for a better performance of given material results in a sub-optimal process limiting the potential of the application. This process needs a comprehensive study of all the influential parameters and their impact on the mechanical and microstructural properties of a fabricated part. Furthermore, there is a need to develop a quantitative system for mapping the material properties and process parameters with the ultimate quality of the fabricated part to achieve improvement in the manufacturing cycle as well as the quality of the final part produced by the PBF process. To address the aforementioned challenges, this research proposes a framework to optimize the process for 316L stainless steel material. This framework characterizes the influence of process parameters on the microstructure and mechanical properties of the fabricated part using a series of experiments. These experiments study the significance of process parameters and their variance as well as study the microstructure and mechanical properties of fabricated parts by conducting tensile, impact, hardness, surface roughness, and densification tests, and ultimately obtain the optimum range of parameters. This would result in a more complete understanding of the correlation between process parameters and part quality. Furthermore, the data acquired from the experiments are employed to develop an intelligent parameter suggestion multi-layer feedforward (FF) backpropagation (BP) artificial neural network (ANN). This network estimates the fabrication time and suggests the parameter setting accordingly to the user/manufacturers desired characteristics of the end-product. Further, research is in progress to evaluate the framework for assemblies and complex part designs and incorporate the results in the network for achieving process repeatability and consistency.

Die Forschung an porösen Hybridmaterialien hat sich rasch entwickelt, und in letzter Zeit ist die Anzahl neuer Strukturen und Zusammensetzungen aufgrund ihrer vielfältigen Anwendungsmöglichkeiten im Bereich des Kristall-Engineering von großem Interesse. Metall-organische Gerüste (metal-organic frameworks, MOFs) sind eine aufstrebende Klasse von Nanomaterialien, deren Eigenschaften durch Variation der Bausteine, die aus Metallionen und organischen Liganden bestehen und sich koordinativ zu einer dreidimensionale Struktur verbinden lassen, leicht angepasst werden können. Eigenschaften wie eine große Oberfläche und eine hohe Porosität verleihen diesen Materialien vielversprechende Eigenschaften, um als Wirtsmaterial verwendet zu werden. Die vorliegende Arbeit konzentriert sich auf die Synthese der Verbindung [Fe3O(H2O)2(OH)(bdc)3]n (bcd = 1,4-Benzoldicarboxylat; MIL-101(Fe), MIL = Materials of Institut Lavoisier), die aus einem carboxylato-verbrückten, oxido-zentriertem, dreikernigen Fe3+-Komplex besteht. Die Struktur besitzt große Poren (Ø: 29 und 34 Å) und eine große Oberfläche mit der Fähigkeit, zahlreiche Moleküle einzuschließen. In der vorliegenden Arbeit wird MIL-101(Fe) als Arzneimittelabgabesystem verwendet. Curcumin, Capecitabin und 5-Fluorouracil (5-FU) wurden als Modellarzneimittel für die Verkapselung in der MIL-101(Fe)-Struktur ausgewählt. Es wurden verschiedene Freisetzungsregime in unterschiedlichen biologischen Medien untersucht. Nach vielversprechenden ersten Ergebnissen bei der Freisetzung dieser Medikamente aus der MIL-101(Fe)-Struktur wurde anschließend die selektive Lasersintertechnik (SLS) verwendet. Die SLS ist ein additives Schichtbauverfahren, das sich in dieser Arbeit als ressourcenschonende Technologie für die schnelle Herstellung erwiesen hat. Die Möglichkeit, die Größe, Form und Geometrie der hergestellten Proben individuell anzupassen, bot die Gelegenheit, die Wirkstofffreisetzung zu modulieren und den Freisetzungszeitraum zu verlängern. / The field of porous hybrid materials has grown rapidly; recently the number of new structures and compositions are of great interest in the crystal-engineering field, due to their various possible applications. Metal-organic frameworks (MOFs) are an emerging class of nanomaterials, whose properties can be easily adjusted by varying the molecular building blocks, obtained from metal ions and organic ligands that can be combined to three-dimensional structures. Properties such as high surface area and high porosity give these materials promising characteristics to be used as host materials. The present work focuses on the synthesis of [Fe3O(H2O)2(OH)(bdc)3]n (bcd = 1,4-benzenedicarboxylate; MIL-101(Fe), MIL = Materials of Institut Lavoisier), composed of carboxylate-bridged, oxido-centered, trinuclear Fe3+ complexes. The iron-based structure features large pore sizes (Ø: 29 and 34 Å) and high surface area with the ability to encapsulate numerous molecules, for use as a drug delivery system in the present work. The curcumin, capecitabine, and 5-fluorouracil (5-FU) were chosen as model drugs for the encapsulation into the MIL-101(Fe) structure. Different delivery regimes were studied in different biological media. After promising initial results with the release of these drugs from the MIL-101(Fe) structure, the selective laser sintering technique (SLS) was introduced subsequently. The SLS is an additive layer manufacturing technique that has emerged in this work as a resourceful technology for rapid manufacturing, the possibility to customize the size, shape, and geometry of the manufactured samples, thus providing the opportunity to modulate the drug release extending it for even longer periods of time.

Den additiva tillverkningsindustrin associeras ofta med en hållbar hushållning av resurser. Trots detta har denna industriavfall med stor potential till vidare användning. Detta kandidatexamensarbete undersöker möjligheten att använda Polyamid 12 (PA12) avfall från selektiv lasersintring (SLS) i formen av filament till en annan additiv tillverkningsmetod, friformsframställning. Avfall från olika delar av SLS-processen försågs av life science företaget Cytiva. Olika blandningar av avfallen extruderades till filament. Innan extrudering undersöktes innehåll samt de termiska egenskaperna hos avfallet med hjälp av differentiell skanningskalometri (DSC), termogravimetrisk analys och fourier transform infraröd spektroskopi. Filamenten analyserades med dragprovning, DSC och svepelektronmikroskopi. Rent obearbetat PA12 pulver och ett kommersiellt PA12 filament användes som referenser vid jämförelse. Blandningarna innehållande avfall från SLS-printerns automatiska rengöringsprocess var kontaminerade med glaspartiklar och blev därför spröda och erhöll en skrovlig yta. Dessa filament gick inte att 3D-printa eftersom glaspartiklar ansamlades i munstycket av printern. Flera filament fick en ojäm och liten diameter och kunde därför inte användas i 3D-printern. Ojämn och liten diameter blev resultatet av bekymmer med sensorn som mäter diametern av filamenten. Dessa filament gjordes av granulerade utskrivna prototyper, pulver nära utskrivna delar och silat pulver långt ifrån de utskrivna delarna. Filament gjorda på blandningar innehållande avfall från dammsugaren som används för att rengöra SLS-printern kunde med framgång skrivas ut i 3D-printern. Dessa filament hade en jämn diameter och innehöll inga större kontamineringar. Det är därför genomförbart att tillverka filament av avfall från alla delar av SLS-processen även om inte alla filament kunde 3D-printas. / Additive manufacturing is often associated with sustainable use of resources. However, this industry still has material waste with great potential for further use. This bachelor thesis examines the opportunity of using Polyamide 12 (PA12) waste from Selective laser sintering (SLS) in the form of filaments for another additive manufacturing method, fused filament fabrication. Waste from different parts of the SLS process were provided from the life science company Cytiva. Several blends of the waste were made into filaments. Prior extrusion, the thermal properties and content of the waste were examined with differential scanning calorimetry (DSC), thermogravimetric analysis and fourier transform infrared spectroscopy. The filaments were analyzed by tensile testing, DSC and scanning electron microscopy. Pure virgin powder of PA12 and a commercial PA12 filament were used as a reference for comparison. The blends containing waste from the SLS printer’s automatic blasting was contaminated with glass beads which resulted in brittle filaments with a rough surface. These filaments were not possible to 3D print with due to accumulation of glass beads in the nozzle of the printer. Several filaments got an uneven and small diameter and could therefore not be 3D printed with. The small and uneven diameter was a result of issues with the sensor measuring the diameter. This includes filaments made of granulated printed prototypes, powder close to the printed parts and sieved powder further away from printed parts. The filaments made of blends including waste from the vacuum cleaner used to clean the SLS printer could successfully be used in printing. These filaments had an even diameter and did not contain any larger contaminations. It is therefore possible to make filaments from waste from all parts of the SLS process although not all filaments could be 3D printed.

The purpose of this thesis is to effectively model the time history of the temperature distribution during the selective laser sintering process and use this information to investigate the resulting relative density. The temperature is a critical parameter of the process because it directly effects the overall quality of the part. First, an efficient, affordable, and reliable simulation was developed within the finite element software, Abaqus. Next, the results from the simulations were compared to the experimental results performed by Wang et al. (2016). The FEA model consisted of a 3 layer simulation. Multiple simulations at various laser recipes were conducted using W-Ni-Fe as the powder material. The P/v (laser power/scanning speed) was plotted against the resulting total time above the melting temperature for various simulation. It was concluded that a linear relationship exists between the P/v parameters used in the laser recipe and the resulting time above the melting temperature. The average R2 values for the W-Ni-Fe simulations for layer 1, 2, 3 were 0.962, 0.950, and 0.939, respectively. Additionally, the experimental results from the Wang et al. (2016) study confirmed that a linear relationship is present. Thus, it can be concluded that the P/v parameters used within the laser recipe has a direct relation to the resulting relative density of the SLS part.

Boolean Satisfiability (SAT) is a problem that holds great theoretical significance along with effective formulations that benefit many real-world applications. While the general problem is NP-complete, advanced solver algorithms and heuristics allow for fast solutions to many large industrial problems. In addition to SAT, many applications rely on generalizations of Satisfiability such as MaxSAT, and Satisfiability Modulo Theories (SMT). Much of the advancement in SAT solver performance has been in the realm of improved sequential solvers with advanced conflict resolution, learning mechanisms, and sophisticated heuristics. There have been some successful demonstrations of massively parallel and hardware-accelerated solvers for SAT, but these have failed to find their way into mainstream usage. This document first presents previous work in Hardware Acceleration of Satisfiability followed by an analysis of why these attempts failed to gain widespread acceptance. It then demonstrates an alternative, hardware-centric approach, based on distributed Stochastic Local Search (SLS) that is better suited to efficient hardware implementation. Then a parallel SLS/CDCL hybrid approach is proposed that is suitable for distributed search with minimal communication overhead while maintaining completeness. Finally the efficacy and flexibility of distributed local search is considered with an adaptation to Weighted Partial MaxSAT (WPMS) and a focused case study on converted Probabilistic Inference instances. / Ph. D. / The Boolean Satisfiability (SAT) problem is an important decision problem that asks whether there exists a solution that satisfies all given constraints over a set of variables that can assume values of either 0 or 1. May real-world decision problems can be translated into SAT, and there exist efficient sequential solvers that can quickly resolve many such instances. Less progress has been made in efficiently scaling SAT solvers to modern multi-core systems and massively parallel hardware accelerators such as GPUs and Field Programmable Gate Arrays (FPGAs). This thesis explore different approaches to solving SAT based decision and optimization problems with the goal of increasing concurrency.

A prosthetic socket worn by an amputee must serve a wide variety of functions, from stationary support to the transfer of forces necessary to move. Fit and comfort are important factors in determining the therapeutic effectiveness of a socket. A socket that does not fit the subject well will cause movement problems and potentially long-term health issues. Because a subject's residual limb changes volume throughout the day, it is desirable that the socket adapt to accommodate volume changes to maintain fit and comfort. This thesis presents research to manufacture adaptive sockets using selective laser sintering (SLS). This additive manufacturing process allows freedom to design a socket that has both compliant areas that can adapt to changes to the residual limb, as well as rigid regions to provide necessary support for the limb. A variety of concepts are discussed that are intended for manufacture by SLS, and that feature flexible inner membranes in various configurations. For each concept the membrane will be inflated or deflated to match the limb’s change in volume and the thesis also presents a study to determine SLS machine parameters for optimal build results. A series of experiments was created to understand the ability of SLS manufactured plastics to be inflated and the possible performance. / text

Silicon nanowires, silicon nanorods, and magnetic nanocrystals have shown interesting size, shape, mechanical, electronic, and/or magnetic properties and many have proposed their use in exciting applications. However, before these materials can be applied, it is critical to fully understand their properties and how to synthesize them economically and reproducibly. Silicon nanowires were synthesized in high boiling point ambient pressure solvents using gold and bismuth nanocrystals seeds and trisilane as the silicon precursor. Reactions temperatures as low as 410°C were used to promote the solution-liquid-solid (SLS) growth of silicon nanowires. The silicon nanowires synthesis was optimized to produce 5 mg of silicon nanowires with average diameters of 30 nm and lengths exceeding 2 [mu]m by adjusting the silicon to gold ratio in the injection mixture and reaction temperature. Silicon nanorods were synthesized using a solution-based arrested-SLS growth approach where gold seeds, trisilane, and a dodecylamine were vital to the success. Dodecylamine was found to prevent gold seed coalescence at high temperatures -- creating small diameter rods -- and bond to the crystalline silicon surface -- preventing silicon nanorod aggregation. Furthermore, an etching strategy was developed using an emulsion of aqua regia and chloroform to remove the gold seeds from the silicon nanorods tip. A thin silicon shell surrounding the gold seed of the silicon nanorod was subsequently observed. Multifunctional colloidal core-shell nanoparticles of iron platinum or iron oxide encapsulated in fluorescent dye doped silica shells were also synthesized. The as-prepared magnetic nanocrystals are initially hydrophobic and were coated with a uniform silica shell using a microemulsion approach. These colloidal heterostructures have the potential to be used as dual-purpose tags, exhibiting a fluorescent signal that could be combined with enhanced magnetic resonance imaging contrast. Compositionally-ordered, single domain, antiferromagnetic L1₂ FePt₃ and ferromagnetic L1₀ FePt nanocrystals were synthesized by coating colloidally-grown Pt-rich or stoichiometricly equal Fe-Pt nanocrystals with thermally-stable SiO₂ and annealing at high temperature. Without the silica coating, the nanocrystals transform predominately into the L1₀ FePt phase due to interparticle diffusion of Fe and Pt atoms. Magnetization measurements of the L1₂ FePt₃ nanocrystals revealed two antiferromagnetic transitions near the bulk Neél temperatures of 100K and 160K. Combining L1₂ FePt₃ nanocrystals with L1₀ FePt nanocrystals was found to produce a constriction in field-dependent magnetization loops that has previously been observed near zero applied field in ensemble measurements of single domain silica-coated L1₀ FePt nanocrystals. Dipole interactions between FePt@SiO₂ nanoparticles with varying SiO₂ shell thickness was also explored. / text

Constrained negative stiffness elements in volume concentrations (1% to 2%) embedded within viscoelastic materials have been shown to provide greater energy absorption than conventional materials [Lakes et al., Nature (London) 410, 565–567 (2001)]. This class of composite materials, called meta-materials, could be utilized in a variety of applications including noise reduction, anechoic coatings and transducer backings. The mechanism underlying the meta-material's behavior relies on the ability of the negative stiffness element to locally deform the viscoelastic material, dissipating energy in the process. The work presented here focuses specifically on the design of the negative stiffness elements, which take the form of buckled beams. By constraining the beam in an unstable, S-shaped configuration, the strain energy density of the beam will be at a maximum and the beam will accordingly display negative stiffness. To date, physical realization of these structures has been limited due to geometries that are difficult to construct and refine with conventional manufacturing materials and methods. By utilizing the geometric freedoms allowed by the Selective Laser Sintering (SLS) machines, these structures can be built and tuned for specific dynamic properties. The objective of this research was to investigate the dynamic behavior of SLS-constructed meso-scale negative stiffness elements with the future intention of miniaturizing the elements to create highly absorptive meta-materials. This objective was accomplished first through the development and analysis of a mathematical model of the buckled beam system. A characterization of the Nylon 11 material was performed to obtain the material properties for the parts that were created using SLS. Applying the mathematical model and material properties, a tuned meso-scale negative stiffness structure was fabricated. Transmissibility tests of the meso-scale structure revealed that the constrained negative stiffness system was able to achieve overall higher damping and vibration isolation than an unconstrained system. Quasistatic behavior of the system indicated that these elements would be ideal for implementation within meta-materials. Based on the results of the meso-scale system, a method to test a representative volume element for a negative stiffness meta-material was developed for future completion. / text

This work outlines an Innovation Gap in technology commercialization and presents a novel tool, the Advanced Technology Innovation Mapping (ATIM) tool to address this gap. The tool aims to support technology commercialization in early stages of & prior to the New Product Development Process. The dissertation includes a detailed rationale, description, history, similar and originating methods for this tool based on Value Engineering and Function Maps for Design. This work also demonstrates on several example studies the use of the tool and evaluates via an exploratory study the usefulness of the tool. Research tests the tool in educational and training programs at the University of Texas at Austin and finds that the tool improves user understating of majority of important factors for technology commercialization (customer, technology, development activities). User feedback supports these conclusions. In the future the tool could be further expanded, more standardized and improved. Additionally, the work proposes further ways to study the tool in different settings and with groups of different sizes beyond this early exploratory study. / text