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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.
681

Návrh protetického chodidla s využitím aditivních výrobních technologií / Design of prosthetic foot using additive manufacturing technologies

Lasota, Marek January 2018 (has links)
Subject of this diploma thesis is a design of a prosthetic foot for an additive manufacturing. It is a dynamic foot made of plastic, designed for an 80 kg patient with a second level of a movement aktivity. From a few concepts is chosen one, which is then optimalized and printed with a MJF method. Functional sample is then undergoing static and cyclic tests according to ISO 10328.
682

Konstrukční optimalizace výrobní linky využitím aditivní technologie SLS / Production line optimalization by using SLS aditive technology

Nakládalová, Tereza January 2018 (has links)
This diploma thesis is focused on additive manufacturing, especially on technology Selective Laser Sintering (SLS) and the implementation of additive manufacturing into existing departments of industry, where current elements of systems are supplemented or directly replaced by new parts produced by these technologies. This thesis solves specific project of manipulation unit for manufacturing line. The main goals of the issue are analysis of current construction design and its deficiency, designing and optimalization of this unit in relation to SLS manufacturing technology, product realization and final evaluating of reached results. Part of the thesis is also design documentation.
683

Konstrukční optimalizace dílu pro tepelný spínač / Structural optimization of the heat switch part

Zemek, Albert January 2020 (has links)
This diploma thesis deals with the design of a structure for heat transfer path of miniaturized heat switch. The focus is on production using SLM additive technology. The aim is to assess the possibilities of using metal 3D printing on a part intended primarily for heat transfer. This work presents several concepts of structure arrangement, which are further analysed and evaluated. The results show the potential of additive technologies in this area and the proposed structures meet the heat transfer requirement according to the calculations used.
684

Výpočtové modelování procesu 3D tisku součástí z PET-G materiálu / Computational modeling of 3D printing structures made of PET-G material

Michálek, Mojmír Cyril January 2020 (has links)
Master’s thesis deals with computational modeling of 3D printing process done by FDM method made from PETG material using finite element method. Research section contains a brief description of 3D printing process modeling possibilities using finite element method and summarizes fundamental mechanical properties of thermoplastics. In practical section there is an evaluation of specimens printed of PETG material tensile tests. Further there is performed a sensitivity analysis of various influences on vertical imperfection of printed part Idler and is done its design modification, which is based on results of this analysis.
685

Untersuchung von additiv gefertigten Prägeformen mit graduellen Eigenschaften hinsichtlich ihres Prägeverhaltens

Mohrich, Maximilian 16 July 2021 (has links)
Ziel dieser Masterarbeit ist die Untersuchung neuartiger Prägeformkonzepte hinsichtlich ihres Prägeverhaltens. Die Konzepte weisen lokal unterschiedliche Materialeigenschaften auf, die zu einer verbesserten Ausprägung von Karton führen sollen. Die Konzepte sollen anhand der Prägeergebnisse und der Abformgenauigkeit evaluiert werden. Dabei ist ein weiteres Ziel der Arbeit, Methoden zur Quantifizierung der Abformgenauigkeit zu finden. Die Herstellung der Konzepte erfolgt mithilfe eines additiven Fertigungssystems, welches mehrere Materialien in einem Bauvorgang verarbeiten kann. Zur Datengewinnung werden Oberflächenscans der geprägten Kartonproben und Werkzeuge durchgeführt. Auf Grundlage dieser Scans werden drei Methoden zur Ermittlung der Abformgenauigkeit vorgeschlagen. Abschließend werden die Werkzeuge anhand der Prägeergebnisse und der ermittelten Abformgenauigkeit bewertet. Weiterhin werden die vorgeschlagenen Methoden miteinander verglichen und deren Vor- und Nachteile diskutiert. Dies gibt Auskunft darüber, unter welchen Bedingungen der Einsatz welcher Methode sinnvoll erscheint.:1. Einleitung 2. Theoretische Grundlagen 2.1 Umformprozesse 2.1.1 Prägen von Faserwerkstoffen 2.1.2 Einsatz von Niederhaltern beim Umformen von Blechen 2.1.2.1 Tiefenziehen 2.1.2.2 Tiefen 2.1.3 Einsatz von Niederhaltern beim Umformen von Karton 2.1.3.1 Ziehen und Pressformen 2.1.3.2 Hydroformen 2.2 Multi-Material-Verarbeitung in der additiven Fertigung 2.2.1 Materialextrusion 2.2.2 Badbasierte Photopolymerisation 2.2.3 Material Jetting 2.2.4 Pulverbettbasiertes Schmelzen 2.2.5 Workflow und Datenvorbereitung 2.3.6 Geeignete Dateiformate 2.3 Soll-Ist-Vergleich von 2.5D-Oberflächendaten 2.3.1 Berechnung von Flächeninhalten und Volumen 2.3.2 Registrierung und Abstandsberechnung von Punktwolken 3. Versuche und Messungen 3.1 Herstellung der Prägeformkonzepte 3.1.1 Beschreibung der Konzepte 3.1.2 Fertigungstechnologie und Materialwahl 3.1.3 Datenvorbereitung für die Polyjet-Fertigung 3.2 Prägeversuche und Datenverarbeitung 3.2.1 Prägeversuche 3.2.2 Oberflächenscan am Keyence 3D-Makroskop 3.3 Ermittlung der Abformgenauigkeit 3.3.1 Flächen- und Volumenberechnung in MatLab & CloudCompare 3.3.2 Abformgenauigkeit nach ICP-Algorithmus & Abstandsberechnung 4. Ergebnisse und Diskussion 4.1 Betrachtung der Prägewerkzeuge 4.2 Betrachtung der Kartonprägungen 4.2.1 Prägeergebnisse nach Flächeninhalt der Profilschnitte 4.2.2 Einfluss der Faserlaufrichtung auf Kartonprägungen 4.2.3 Prägeergebnisse nach Volumen der Punktwolken 4.3 Betrachtung der Abformgenauigkeit 4.3.1 Abformgenauigkeit nach Flächeninhalt & Volumen 4.3.2 Abformgenauigkeit nach ICP-Algorithmus & Abstandsberechnung 4.4 Bewertung der Methoden zur Ermittlung der Abformgenauigkeit 4.5 Beurteilung des Bedienereinflusses bei der Datenverarbeitung am Keyence 5. Zusammenfassung und Ausblick Literaturverzeichnis Eidesstattliche Erklärung / The aim of this master thesis is to investigate novel embossing die concepts with regard to their embossing behavior. The concepts have locally different material properties, which should lead to an improved embossing of cardboard. The concepts are to be evaluated on the basis of the embossing results and the impression accuracy. A further aim of the work is to find methods for quantifying the impression accuracy. The concepts will be manufactured using an additive manufacturing system that can process multiple materials in a single build process. Surface scans of the embossed cardboard samples and tools are performed to obtain data. Based on these scans, three methods are proposed to determine the impression accuracy. Finally, the tools are evaluated based on the embossing results and the determined impression accuracy. Furthermore, the proposed methods are compared with each other and their advantages and disadvantages are discussed. This provides information on the conditions under which the use of which method appears to be sensible.:1. Einleitung 2. Theoretische Grundlagen 2.1 Umformprozesse 2.1.1 Prägen von Faserwerkstoffen 2.1.2 Einsatz von Niederhaltern beim Umformen von Blechen 2.1.2.1 Tiefenziehen 2.1.2.2 Tiefen 2.1.3 Einsatz von Niederhaltern beim Umformen von Karton 2.1.3.1 Ziehen und Pressformen 2.1.3.2 Hydroformen 2.2 Multi-Material-Verarbeitung in der additiven Fertigung 2.2.1 Materialextrusion 2.2.2 Badbasierte Photopolymerisation 2.2.3 Material Jetting 2.2.4 Pulverbettbasiertes Schmelzen 2.2.5 Workflow und Datenvorbereitung 2.3.6 Geeignete Dateiformate 2.3 Soll-Ist-Vergleich von 2.5D-Oberflächendaten 2.3.1 Berechnung von Flächeninhalten und Volumen 2.3.2 Registrierung und Abstandsberechnung von Punktwolken 3. Versuche und Messungen 3.1 Herstellung der Prägeformkonzepte 3.1.1 Beschreibung der Konzepte 3.1.2 Fertigungstechnologie und Materialwahl 3.1.3 Datenvorbereitung für die Polyjet-Fertigung 3.2 Prägeversuche und Datenverarbeitung 3.2.1 Prägeversuche 3.2.2 Oberflächenscan am Keyence 3D-Makroskop 3.3 Ermittlung der Abformgenauigkeit 3.3.1 Flächen- und Volumenberechnung in MatLab & CloudCompare 3.3.2 Abformgenauigkeit nach ICP-Algorithmus & Abstandsberechnung 4. Ergebnisse und Diskussion 4.1 Betrachtung der Prägewerkzeuge 4.2 Betrachtung der Kartonprägungen 4.2.1 Prägeergebnisse nach Flächeninhalt der Profilschnitte 4.2.2 Einfluss der Faserlaufrichtung auf Kartonprägungen 4.2.3 Prägeergebnisse nach Volumen der Punktwolken 4.3 Betrachtung der Abformgenauigkeit 4.3.1 Abformgenauigkeit nach Flächeninhalt & Volumen 4.3.2 Abformgenauigkeit nach ICP-Algorithmus & Abstandsberechnung 4.4 Bewertung der Methoden zur Ermittlung der Abformgenauigkeit 4.5 Beurteilung des Bedienereinflusses bei der Datenverarbeitung am Keyence 5. Zusammenfassung und Ausblick Literaturverzeichnis Eidesstattliche Erklärung
686

Fabrication and Testing of Biomimetic Microstructures for Walkway Tribometers

Haney, Christopher Willard 12 1900 (has links)
The main objective of this work is to give contribution in both additive manufacturing (AM) and tribometry derived from the application and study of materials available with the use of biomimetic designs. Additional contributions are determining what effects treatments for flooring surfaces may have on the dynamic coefficient of friction and the effects of these products on common surfaces. The validity of the proposed methodology for a proof of concept was demonstrated by comparing measured dynamic coefficient of friction for designs using standardized equipment and comparing these values to plantar skin tested using an accepted and standardized testing method that has been extensively researched and validated. Initial biomimetic designs and characteristics unique to each design were researched and compared. Eleven designs were selected to be fabricated, tested, and compared to select the most desirable applications for further investigation. Research into potential treatments commercially available for use was done to determine the efficacy of these products. Prototype sensor designs were selected and fabricated using direct light processing (DLP) technology. Examination of the measured values was done through an analysis of the variances in the response variable and comparisons using Fisher and Tukey pairwise comparison method. Future work recommendations are provided for further development and improvement of the topics presented in this thesis.
687

Study of Nano-Transfer Technology for Additive Nanomanufacturing and Surface Enhanced Raman Scattering

Li, Jiaqi 09 August 2021 (has links)
No description available.
688

Powder Bed Surface Quality and Particle Size Distribution for Metal Additive Manufacturing and Comparison with Discrete Element Model

Yee, Irene 01 March 2018 (has links)
Metal additive manufacturing (AM) can produce complex parts that were once considered impossible or too costly to fabricate using conventional machining techniques, making AM machines an exceptional tool for rapid prototyping, one-off parts, and labor-intensive geometries. Due to the growing popularity of this technology, especially in the defense and medical industries, more researchers are looking into the physics and mechanics behind the AM process. Many factors and parameters contribute to the overall quality of a part, one of them being the powder bed itself. So far, little investigation has been dedicated to the behavior of the powder in the powder bed during the lasering process. A powder spreading machine that simulates the powder bed fusion process without the laser was designed by Lawrence Livermore National Laboratory and was built as a platform to observe powder characteristics. The focus for this project was surface roughness and particle size distribution (PSD), and how dose rate and coating speed affect the results. Images of the 316L stainless steel powder on the spreading device at multiple layers were taken and processed and analyzed in MATLAB to access surface quality of each region. Powder from nine regions of the build plate were also sampled and counted to determine regional particle size distribution. As a comparison, a simulation was developed to mimic the adhesive behavior of the powder, and to observe how powder distributes powder when spread.
689

Utveckling av insatsmodul till en Arcam S12 EBM-maskin : För möjliggörande av småskaliga tester med mindre pulveråtgång

Jonasson, Jack, Ottosson, Jens January 2019 (has links)
Arbetet behandlar utvecklingsprocessen för en insats till en ARCAM S12 Electron Beam Melting-maskin.   Behovet består i att dagens maskin kräver en full tank med tillverk-ningsmaterial för att kunna användas. Den överdrivna materialtillför-seln leder till att maskinen ej kan ses som lämplig för materialforskning, då nya material måste tillverkas i stora satser varav en stor del går som svinn. Målet med arbetet blev därför att utveckla en insats till maskinen, som skulle göra den gångbar att använda vid materialforskning, utan att permanent påverka ursprungsfunktionen.   Den utvecklade insatsen har som funktion att sänka materialanvänd-ningen i maskinen, och därigenom göra maskinen applicerbar för materialforskning. Detta genom att minska byggytan och skapa en mer sofistikerad materialmatning än originalutförandets. Materialmatningen är också modulär, på så sätt att mängden materialpulver som matas ut per cykel kan varieras med olika insatser.   Under arbetets gång behandlas alla processens steg, från målspecifikat-ionen till det slutgiltiga konstruktionsunderlaget. Projektet startade med en funktionsanalys och uppställande av en målspecifikation. Därefter startade konceptgenereringsprocessen med både kreativa och mer stringenta utvecklingsmetoder. Efter detta genomfördes konceptval med flera strukturerade konceptvalsmetoder. Det valda konceptet modellerades sedan i sin slutgiltiga form i SolidWorks. Via SolidWorks interna ritningssystem ritades även konstruktionsunderlag till insatts-modulen.   Projektets resultat är ett färdigt konstruktionsunderlag för en modul som passar i en ARCAM S12 EBM-maskin. Denna modul minskar byggvolymen till 110x110xbygghöjden i millimeter, och likriktar mängden material applicerat mellan lagerna. / This thesis work is focused on the product development of an insert module for an ARCAM S12 Electron Beam Melting machine The need for an insert module comes from the fact that the machine requires a full tank of building material to operate as intended. With concern to the large building volume the original machine cannot be seen as a viable alternative for materials research, because such research often uses expensive experimental materials. The goal for the module is therefore to lower the use of building material, and trough that make the machine viable for materials research without permanently affecting the original function. Another important function of the new module is the possibility to control and synchronize the amount of material dispensed between layers of the build.     During the length of the thesis, the entire development process of the module is discussed. From the target specification, to the finished blueprints.   The process started with the establishment of a target specification, followed by a phase of concept development containing both creative and stringent methods. After these concepts had been evaluated and culled through structured methods a final concept was selected. This concept was then modeled in Solid Works and technical drawings of the model was made for the blueprint.   The result of the thesis work is a finished blueprint for an insert module that fits an ARCAM S12 EBM machine. This module has lowered the build volume to 110x110xthe build height in millimeters, and has the possibility to synchronize the amount of material dispensed between layers. / <p>Betyg 190909</p>
690

BUILDABILITY AND MECHANICAL PERFORMANCE OF ARCHITECTURED CEMENT-BASED MATERIALS FABRICATED USING A DIRECT-INK-WRITING PROCESS

Mohamadreza Moini (8922227) 16 June 2020 (has links)
<p></p><p>Additive Manufacturing (AM) allows for the creation of elements with novel forms and functions. Utilizing AM in development of components of civil infrastructure allows for achieving more advanced, innovative, and unique performance characteristics. The research presented in this dissertation is focused on development of a better understanding of the fabrication challenges and opportunities in AM of cement-based materials. Specifically, challenges related to printability and opportunities offered by 3D-printing technology, including ability to fabricate intricate structures and generate unique and enhanced mechanical responses have been explored. Three aspects related to 3D-printing of cement-based materials were investigated. These aspects include: fresh stability of 3D-printed elements in relation to materials rheological properties, microstructural characteristics of the interfaces induced during the 3D-printing process, and the mechanical response of 3D-printed elements with bio-inspired design of the materials’ architecture. This research aims to contribute to development of new pathways to obtain stability in freshly 3D-printed elements by determining the rheological properties of material that control the ability to fabricate elements in a layer-by-layer manner, followed by the understanding of the microstructural features of the 3D-printed hardened cement paste elements including the interfaces and the pore network. This research also introduces a new approach to enhance the mechanical response of the 3D-printed elements by controlling the spatial arrangement of individual filaments (i.e., materials’ architecture) and by harnessing the weak interfaces that are induced by the 3D-printing process. </p><br><p></p>

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