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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.
471

ADAPTION OF A HEATSINK TO ADDITIVE MANUFACTURING. : INCLUDING A GUIDE TO INDUSTRIAL STARTUP OF AM. / Anpassning av en elektronikkylare till Additiv Tillverkning. : Inklusive en industriell uppstartsguide för AM.

Ingman, Richard January 2019 (has links)
This thesis is an investigation of the current status of additive manufacturing (AM) regarding different technologies, the level of implementation in industry and the future obstacles for further implementation. As a secondary objective, an existing heatsink for electronic equipment was redesigned, adapted to and improved using the design advantages of AM, and was later manufactured through 3D-printing in aluminium (AlSi10Mg). The thesis resulted in a summarized roadmap of recommended actions for Saab Surveillance in Järfälla in the near future. And a redesigned heatsink, which was tested to hold a static pressure of 30 bar, and simulated to achieve the same pressure drop in the channel and withstand the same vibration load as the old heatsink. At the same time, the new design reduced the total weight by 20% and increased the heat transferring surface area of the channel by 100%, potentially doubling the heat transfer capability. / Detta examensarbete har undersökt den nuvarande statusen hos additiv tillverkning (AM) vad gäller olika teknologier, hur långt implementeringen i industrin kommit och framtida hinder som måste lösas för vidare implementering. Som sekundärt mål för projektet har en existerande elektronikkylare designats om och förbättrats med hjälp av designfördelarna hos AM, och tillverkades sedan genom 3D-printning i aluminium (AlSi10Mg). Arbetet har resulterat i en sammanfattad ’roadmap’ med rekommendationer för vad Saab Surveillance i Järfälla bör göra inom AM den närmaste tiden, samt en ny kylare som framgångsrikt trycktestades upp till 30 bar. Genom simuleringar visades den uppnå samma tryckfall och klara samma vibrationer som den tidigare kylaren, samtidigt som den väger 20% mindre och har en 100% ökning av kylkanalens våta area vilket potentiellt innebär en dubblering av kylförmågan.
472

Ionic Liquid–Based 3D Printed Soft Pressure Sensors and Their Applications

Emon, Md Omar Faruk 25 August 2020 (has links)
No description available.
473

Additive Manufacturing in Spacecraft Design and In-Space Robotic Fabrication of Large Structures

Spicer, Randy Lee 31 August 2023 (has links)
Additive Manufacturing (AM, 3D printing) has made significant advancements over the past decade and has become a viable alternative to traditional machining techniques. AM offers several advantages over traditional manufacturing techniques including improved geometric freedom, reduction in part lead time, cost savings, enhanced customization, mass reduction, part elimination, and remote production. There are many different AM processes with the most commonly used process being Fused Filament Fabrication (FFF). Small satellites have also made significant advancements over the past two decades with the number of missions launched annually increased by orders of magnitude over that time span. Small satellites offer several advantages compared to traditional spacecraft architectures including increased access to space, lower development costs, and disaggregated architectures. On-orbit manufacturing and assembly have become major research and development topics for government and commercial entities seeking the capability to build very large structures in space. AM is well suited on-orbit manufacturing since the process is highly automated, produces little material waste, and allows for a large degree of geometric freedom. This dissertation seeks to address three major research objectives regarding applications of additive manufacturing in space systems: demonstrate the feasibility of 3D printing an ESPA class satellite using FFF, develop a FFF 3D printer that is capable of operating in high vacuum and characterize its performance, and analyze the coupled dynamics between a satellite and a robot arm used for 3D printing in-space. This dissertation presents the design, finite element analysis, dynamic testing, and model correlation of AdditiveSat, an additively manufactured small satellite fabricated using FFF. This dissertation also presents the design, analysis, and test results for a passively cooled FFF 3D printer capable of manufacturing parts out of engineering grade thermoplastics in the vacuum of space. Finally, this dissertation presents a numerical model of a free-flying small satellite with an attached robotic arm assembly to simulate 3D printing structures on-orbit with analysis of the satellite controls required to control the dynamics of the highly coupled system. / Doctor of Philosophy / 3D printing has made significant advancements over the past decade and has become common place in offices, schools, and even the homes of hobbyist. 3D printing has become an alternative to traditional machining techniques, such as machining parts from blocks of material. 3D printing offers several advantages over traditional manufacturing techniques including improved geometry freedom, reduction in part lead time, cost savings, enhanced customization, mass reduction, part elimination, and remote production. There are many different types of 3D printing with the most commonly used process being Fused Filament Fabrication (FFF) in which a thermoplastic is melded by a hotend and then extruded through a nozzle to deposited material layer-by-layer onto a printed part. Small satellites have also made significant advancements over the past two decades with the number of missions launched annually greatly increased over that time span. Small satellites offer several advantages compared to traditional spacecraft including increased access to space and lower development costs. On-orbit manufacturing and assembly have become major research and development topics for government and commercial entities seeking the capability to build very large structures in space. This dissertation seeks to address three major research objectives regarding applications of additive manufacturing in space systems: demonstrate the feasibility of 3D printing an ESPA class satellite using FFF, develop a FFF 3D printer that is capable of operating in high vacuum and characterize its performance, and analyze the coupled dynamics between a satellite and a robot arm used for 3D printing in-space. This dissertation presents the design, analysis, and test results of AdditiveSat, a 3D printed small satellite made using FFF. This dissertation also presents the development of a FFF 3D printer capable of operating in the vacuum of space. Finally, this dissertation presents a numerical simulation that models 3D printing structures on-orbit with a small satellite equipped with a robot arm.
474

Bioinspired Material Design and Performance Characterization for Extreme Environment

Banik, Arnob 06 December 2022 (has links)
No description available.
475

Fracture Toughness of Carbon Fiber Composite Material

Rea, Allison 14 December 2022 (has links)
No description available.
476

Design and Testing of a Hybrid Direct Ink Writing and Fused Deposition Modeling Multi-Process 3D Printer

Losada, Alexander X 01 January 2022 (has links)
Multi-material 3D Printing allows the ability to fabricate parts with tuned mechanical properties, multi-process 3D printing widens the choices of available fabrication materials. The objective of this study is to build a custom 3D printing test bed that is capable of printing multi-material parts with fused deposition modeling and direct ink writing techniques. A 3D printer, controlled by an industrial motion control system, with FDM and DIW capabilities was built by combining FDM extruders with a pneumatic dispensing system on a single platform. By utilizing the Direct Ink Writing function, we expand the number of printable materials to include some off the shelf silicones and epoxies, as well as custom, user made, materials. This study will further expand the manufacturing and research capabilities within the additive manufacturing discipline.
477

Case Report: Clinical Use of a Patient-Individual Magnetic Resonance Imaging-Based Stereotactic Navigation Device for Brain Biopsies in Three Dogs

Gutmann, Sarah, Flegel, Thomas, Müller, Marcel, Möbius, Robert, Matiasek, Kaspar, König, Florian, Winkler, Dirk, Grunert, Ronny 16 October 2023 (has links)
Three-dimensional (3D) printing techniques for patient-individual medicine has found its way into veterinary neurosurgery. Because of the high accuracy of 3D printed specific neurosurgical navigation devices, it seems to be a safe and reliable option to use patient- individual constructions for sampling brain tissue. Due to the complexity and vulnerability of the brain a particularly precise and safe procedure is required. In a recent cadaver study a better accuracy for the 3D printed MRI-based patient individual stereotactic brain biopsy device for dogs is determined compared to the accuracies of other biopsy systems which are currently used in veterinary medicine. This case report describes the clinical use of this 3D printed MRI-based patient individual brain biopsy device for brain sampling in three dogs. The system was characterized by a simple handling. Furthermore, it was an effective and reliable tool to gain diagnostic brain biopsy samples in dogs with no significant side effects.
478

Developing 3D Printed Integrated Microfluidic Devices for Microchip Electrophoresis Separation of Preterm Birth Biomarkers

Esene, Joule E. 06 November 2023 (has links) (PDF)
Preterm birth is a global health challenge and the leading cause of neonatal mortality. Each year, about 15 million babies are born preterm globally. Traditional tools that have been exploited for the detection of preterm birth biomarkers are expensive, time consuming, or lack multiplexing capabilities. The work described in this dissertation highlights techniques developed to detect preterm birth biomarkers rapidly and accurately in the effort to mitigate preterm birth risk. In this dissertation, I first demonstrated the use of stereolithography digital light processing-based 3D printing and microfluidics for the development of microfluidic devices that had microvalves for fluid control. I then used these devices for microchip electrophoresis and fluorescence detection of five preterm birth biomarkers from a published panel. Next, I presented developments in 3D printed microchip electrophoresis device design. I separated amino acids and preterm birth biomarkers in a serpentine device design, obtaining good resolution, separation efficiency, and improved preterm birth biomarker peak capacity. Finally, I demonstrated the integration of solid-phase extraction with microchip electrophoresis in 3D printed microfluidic devices. These integrated devices enabled a seamless transition from preterm birth biomarker enrichment and labeling to microchip electrophoresis separation and fluorescence detection. The work described in this dissertation shows promise in advancing key tools needed to address preterm birth risk rapidly and effectively.
479

Konstruktion av extruderingsmaskin för eget bruk / Construction of Desktop Extruder for Private Use

Athley, Axel, Johnsson Kronovall, Victor January 2023 (has links)
I och med att additiv tillverkning blir allt vanligare i dagens samhälle kommer dess ekologiska, samt ekonomiska effekter bli alltmer tydliga och viktiga att ta i beaktning. Tekniken utvecklas och är numera tillgänglig för i stort sett alla. Detta har gjort att 3D-skrivare bland privatpersoner blivit vanligt förekommande. Det har lett till att mer filament går åt till användning av 3D-skrivare, vilket också leder till att mer material går till spillo. Ett av de vanligaste filamentmaterialen inom detta område är PLA. PLA har många fördelar när det kommer till 3D-skrivning, en av nackdelarna är dock svårigheten med att ta till vara på spillmaterialet då det är svårt att återvinna. Detta bidrar till ett ökat behov av att kunna återvinna filamentet själv, och vad kan då vara bättre än att göra det till nytt filament som kan användas igen? Detta är bra ur både ekonomiska och ekologiska hållbarhetsaspekter. Av denna anledning har en extruderingsmaskin designats så att privatpersoner och mindre aktörer ska kunna bygga en egen. På så sätt kan de ta hand om sitt spillmaterial på ett vis som närmar sig en cirkulär ekonomi. Projektet inleddes med en bakgrundsundersökning för att undersöka befintliga lösningsalternativ som redan finns och för att få tips och inspiration. Sedan genomfördes en idégenereringsprocess för att ta fram så många idéer som möjligt för att därigenom förbättra möjligheterna till att hitta en exceptionell lösning. När ett koncept hade valts gjordes jämförelser mellan olika komponenter. Sedan gjordes beräkningar på de valda komponenterna. Detta för att kunna dimensionera dem, delvis för att vara säker på att den håller, men även för att veta hur mycket värme och mekanisk energi som kommer att behöva tillföras i maskinen för att den ska fungera som tänkt. Ett komplett designförslag har tagits fram tillsammans med dimensioner på komponenter för att underlätta för ett eventuellt privat byggprojekt av denna extruderingsmaskin. Vissa ändringar kan göras beroende på budget och tillgänglighet av komponenter. De ändringar som görs kan leda till att även beräkningar behöver göras om eller justeras. Flera av måtten och dimensionerna på vissa komponenter kan ses som överdrivna, detta är på grund av att de ska klara det högsta tryck och krafter som kan uppstå. Dessa uppstår enbart när det satt stopp i matrisen. Att det sätter stopp helt och hållet kommer troligtvis vara ovanligt, men om det händer är det viktigt att maskinen klarar av ett sådant stopp. Till sist kommer alla inställningar behöva justeras och testas på egen hand. Detta är på grund av att maskinen inte har byggts, utan enbart är ett koncept. Dessutom kommer den troligtvis fungera lite annorlunda för alla som bygger den då det kommer att vara skillnader i montering och komponenter. / In today's society additive manufacturing is getting more and more common. The technique is developing and is within reach for almost everyone. It is within the private sector the biggest growth of popularity can be seen. The increased usage of this technology has led to increased usage of plastic within this field. This means that the waste has increased as well. One of the most common materials for 3D-printing is PLA, this is because of a few different benefits. Although it has its cons, one of the bigger drawbacks is that it is hard to recycle. There are very few recycling facilities that can take care of PLA. This means that it is necessary to find another way to handle the otherwise wasted PLA. One way to do this is by making it possible for people to do it themselves, therefore the goal of this project, to develop an extruder for individuals. The extruder is supposed to use old PLA-prints to make new filament. This is good from an ecological perspective as well as an economic one. The extruder is designed to make it possible for the user to assemble it on their own. The project started with a background search, this was to get a better picture of the problem, but also to see what alternative solutions already exists. After this the phase of brainstorming as many ideas as possible started. When a concept had been chosen it was developed even further and calculations were done to ensure that it would work as intended. The calculations contained aspects such as strength of the base and pipe, but also the amount of energy needed from the motor and heaters to fulfill their respective functions. A complete design proposal for the extruder has been established, this together with supporting calculations and measurements for the different components. A few changes can be done to modify the machine for individual needs, however the calculations might have to be adapted depending on the changes that are made. A few of the dimensions on certain components might seem exaggerated. This is because they need to be able to handle the highest pressures and forces that may occur. These pressures and forces are only reached when the machine gets clogged up. The machine clogging should be unusual, but once it happens it might break without proper dimensions. At last smaller adjustments might have to be made by the user. This is because the machine has not been built, it is just a concept. Also, there will be differences depending on what specific component is chosen and the individual assembling process.
480

Factores ergonómicos en el diseño de órtesis de mano para rehabilitación sensoriomotora de neuropatías radial, cubital y mediana.

Bula Oyola, Ena Lucía 20 November 2023 (has links)
[ES] Las neuropatías periféricas son patologías que deterioran los nervios situados fuera del sistema nervioso central y que afectan significativamente las funciones sensoriomotoras. Existen varias alternativas terapéuticas, entre ellas las órtesis. Estos dispositivos se encargan de proteger la musculatura, corregir alteraciones y asistir la función de la extremidad afectada. Su efectividad está demostrada; sin embargo, depende directamente del adecuado cumplimiento del protocolo de uso. El objetivo principal de esta tesis fue identificar los criterios ergonómicos aplicables al desarrollo de órtesis que incrementen la adherencia al tratamiento en pacientes con neuropatías radial, cubital y mediana. Con este fin, se evaluó la posibilidad de optimizar las propiedades terapéuticas a partir de la inclusión de agentes electrofísicos en el dispositivo. Para ello, se llevó a cabo una revisión sistemática y metaanálisis de la evidencia disponible en los en los últimos cuarenta años en torno a la efectividad de las principales modalidades aplicadas. Se determinó que algunas modalidades cuando se aplican conjuntamente a una órtesis se ven favorecidas. No obstante, ninguno de los resultados de la revisión puede considerarse clínicamente significativos. Posteriormente, se planteó un protocolo de co-creación que incluyó las principales fases de un proceso de diseño con la participación de usuarios de órtesis. La primera fase, Perspectiva de Usuarios, contó con 100 sujetos con neuropatías periféricas. Se obtuvo información tanto para la identificación de necesidades y preferencias como para la clasificación de los aspectos que intervienen en la adherencia. Se emplearon modelos lineales y no lineales, como el modelo de Kano. Se encontró que este modelo permite una identificación más precisa acerca de qué atributos tienen más importancia y del grado de influencia de éstos en la adherencia. Asimismo, se comprobó que la satisfacción es una medida indirecta de la importancia y constituye un adecuado predictor de la adherencia a órtesis. Por el contrario, la importancia explícita no cuenta con la misma fiabilidad. La segunda fase, Diseño Participativo, incluyó a 9 personas voluntarias que evaluaron las propuestas de órtesis y brindaron recomendaciones de diseño. En la tercera fase, Modelado y Prototipado, se produjeron una serie de iteraciones de diseño, dando lugar a un nuevo desarrollo de órtesis. En la cuarta fase, Validación, se comprobó la funcionalidad y usabilidad de la órtesis con 11 sujetos sanos a través de un estudio con electromiografía de superficie. Con ello se demostró que la inclusión de un mecanismo deformable en el diseño del muelle articular permite una óptima asistencia motora en condiciones normales. Por último, en la fase de Desarrollo Final, se fabricó un prototipo funcional de órtesis radial teniendo en cuenta las oportunidades de mejora identificadas. / [CA] Les neuropaties perifèriques són patologies que deterioren els nervis situats fora del sistema nerviós central i que afecten significativament les funcions sensorimotrius. Hi ha diverses alternatives terapèutiques, entre elles les òrtesis. Aquests dispositius s'encarreguen de protegir la musculatura, corregir alteracions i assistir la funció de l'extremitat afectada. La seva efectivitat està demostrada; no obstant això, depèn directament del correcte compliment del protocol d'ús. L'objectiu principal d'aquesta tesi va ser identificar els criteris ergonòmics aplicables al desenvolupament d'ortesis que incrementen l'adherència al tractament en pacients amb neuropaties radial, cubital i mitjana. Amb aquest fi, es va avaluar la possibilitat d'optimitzar les propietats terapèutiques a partir de la inclusió d'agents electrofísics en el dispositiu. Per a això, es va dur a terme una revisió sistemàtica i metaanàlisi de l'evidència disponible en els últims 40 anys entorn de l'efectivitat de les principals modalitats aplicades. Es va determinar que algunes modalitats, quan s'apliquen conjuntament a una òrtesi, es veuen beneficiades. No obstant això, cap dels resultats de la revisió va ser clínicament significatiu. Posteriorment, es va plantejar un protocol de co-creació que va incloure les principals fases d'un procés de disseny amb la participació d'usuaris d'ortesis. La primera fase, Perspectiva d'Usuaris, va comptar amb 100 subjectes amb neuropaties perifèriques. Es va obtenir informació tant per a la identificació de necessitats i preferències com per a la classificació dels aspectes que intervenen en l'adherència. Es van emprar models lineals i no lineals, com el model de Kano. Es va trobar que aquest model permet una identificació més precisa sobre quins atributs tenen més importància i el grau d'influència d'aquests en l'adherència. Així mateix, es va comprovar que la satisfacció és una mesura indirecta de la importància i constitueix un predictor adequat de l'adherència a ortesis. Per contra, la importància explícita no compta amb la mateixa fiabilitat. La segona fase, Disseny Participatiu, va incloure 9 persones voluntàries que van avaluar les propostes d'ortesis i van donar recomanacions de disseny. En la tercera fase, Modelatge i Prototipatge, es van produir una sèrie d'iteracions de disseny, donant lloc a un nou desenvolupament d'òrtesis. En la quarta fase, Validació, es va comprovar la funcionalitat i usabilitat de l'òrtesi amb 11 subjectes sans mitjançant un estudi amb electromiografia de superfície. Amb això es va demostrar que la inclusió d'un mecanisme deformable en el disseny del moll articular permet una òptima assistència motora en condicions normals. Finalment, en la fase de Desenvolupament Final, es va fabricar un prototip funcional d'òrtesi radial tenint en compte les oportunitats de millora identificades. / [EN] Peripheral neuropathies are pathologies that deteriorate the nerves located outside the central nervous system and significantly affect sensorimotor functions. There are several therapeutic alternatives, including orthoses. These devices are responsible for protecting the musculature, correcting alterations, and assisting the function of the affected limb. Their effectiveness has been demonstrated. However, it depends directly on proper compliance with the usage protocol. The main objective of this thesis was to identify ergonomic criteria applicable to the development of orthoses that increase treatment adherence in patients with radial, ulnar, and median neuropathies. To this end, the possibility of optimizing therapeutic properties by including electrophysical agents in the device was evaluated. To achieve this, a systematic review and meta-analysis of the available evidence in the last 40 years regarding the effectiveness of the primary applied modalities. It was determined that some modalities are favored when used in conjunction with an orthosis. Nevertheless, none of the review results were clinically significant. Subsequently, a co-creation protocol was proposed, involving the main phases of a design process with the participation of orthosis users. The first phase, User Perspective, involved 100 subjects with peripheral neuropathies. Information was obtained for the identification of needs and preferences, as well as for the classification of aspects involved in adherence. Linear and non-linear models, such as the Kano model, were employed. It was found that this model allows a more precise identification of which attributes are more important and their influence on adherence. Additionally, it was verified that satisfaction is an indirect measure of importance and constitutes an adequate predictor of orthosis adherence. In contrast, explicit importance is not a reliable indicator. The second phase, Participatory Design, included nine voluntary individuals who evaluated orthosis proposals and provided design recommendations. In the third phase, Modeling and Prototyping, a series of design iterations were carried out, resulting in a new orthosis development. The fourth phase, Validation, tested the functionality and usability of the orthosis with 11 healthy subjects through a study with surface electromyography. It was demonstrated that including a deformable mechanism in the joint spring design allows optimal motor assistance under normal conditions. Finally, in the Final Development phase, a functional prototype of the radial orthosis was manufactured, considering the identified opportunities for improvement. / Bula Oyola, EL. (2023). Factores ergonómicos en el diseño de órtesis de mano para rehabilitación sensoriomotora de neuropatías radial, cubital y mediana [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/199996

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