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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.
441

Sestavení a ověření funkčnosti domácí 3D tiskárny / Assembling and Functional Verification of a Home 3D Printer

Tesař, Jaroslav January 2014 (has links)
This thesis was created as a bachelor project in the Faculty of Mechanical Engineering at VUT in Brno. In the theoretical part, the additive technology Rapid Prototyping is introduced together with the most common methods, followed by the assessment of advantages and disadvantages of the new technology and its possible uses in various fields of human activity. In the experimental part of the diploma thesis was assembled and the printing parameters were set. Consequently the comparison models were printed on the 3D home printer and on professional printer Dimension uPrint. The accuracy of the printers is compared. The thesis concludes with the analysis of technical and economical parameters.
442

"Copy and Paste"

Ostendorff, Saskia Friederike 31 October 2019 (has links)
Der 3D-Druck greift als Vervielfältigungsgerät in das Kernrecht des Urhebers ein. Der private Nutzer kann mit “Copy and Paste” alle Objekte drucken. Das Vervielfältigungsrecht des Urhebers wird durch eine private Nutzung von 3D-Druckern zu Hause, in FabLabs, Hackerspaces oder 3D-Druck Copyshops eingeschränkt werden. Das Urheberrecht als Eigentumsrecht aus Art. 14 GG wird mit dem Recht des Nutzers auf Information und Meinungsfreiheit nach Art. 5 GG abgewogen. Diese Abwägung ist in Zeiten der Digitalisierung, des Internets und der neuen Technologien eine der wichtigsten für das geistige Eigentum. Mit dem 3D-Druck steht und fällt die Frage nach der Vervielfältigungsfreiheit und der Suche nach alternativen Vergütungsmodellen. Schafft der § 53 Abs.1, Abs. 7 UrhG einen Interessenausgleich zwischen Urhebern und Nutzern? Die Arbeit untersucht die Vervielfältigung von Werken der angewandten Kunst unter dem Aspekt der Geburtstagszugentscheidung des BGH und macht die notwendige rechtlichen Änderungen deutlich. / 3D printing is not only a technical topic but also a topic for creators. The 3D printer intervenes the core right of creators and makes copyright issues obvious. 3D printing is a new usage under section § 31 UrhG. The private user can "copy and paste" to reproduce any objects. The question is how the right of the creator can be restricted by private use of 3D printers at home, in FabLabs, hackerspaces or 3D printing copy shops. Copyright as a property right in Art. 14 GG faces the user's right to information and freedom of expression under Art. 5 GG. Balancing these two fundamental rights is one of the crucial questions for intellectual property in times of digitization, internet and new technologies, as 3D printing is also about freedom of reproduction and alternative compensation models. To what extent creates section § 53 para. 1, para. 7 UrhG a balance of interests for applied art? This present works examines the reproduction of applied art under the “Geburtstagszugentscheidung” and the necessity of reforming legislation in the age of 3D printers.
443

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>
444

Experimental and Modeling Study of Gas Adsorption in Metal-Organic Framework Coated on 3D Printed Plastics

Tejesh Charles Dube (8812424) 08 May 2020 (has links)
<div> <p>Metal-organic frameworks (MOFs) are a class of compounds consisting of metal ions or clusters coordinated to organic ligands in porous structure forms. MOFs have been proposed in use for gas adsorption, purification, and separation applications. This work combines MOFs with 3D printing technologies, in which 3D printed plastics serve as a mechanical structural support for MOFs powder, in order to realize a component design for gas adsorption. The objective of the thesis is to understand the gas adsorption behavior of MIL-101 (Cr) MOF coated on 3D printed PETG, a glycol modified version of polyethylene terephthalate, through a combined experimental and modeling study. The specific goals are: (1) synthesis of MIL-101 (Cr) MOFs; (2) nitrogen gas adsorption measurements and microstructure and phase characterization of the MOFs; (3) design and 3D printing of porous PETG substrate structures; (4) deposition of MOFs coating on the PETG substrates; and (5) Monte Carlo (MC) modeling of sorption isotherms of nitrogen and carbon dioxide in the MOFs.</p><p>The results show that pure MIL-101 (Cr) MOFs were successfully synthesized, as confirmed by the scanning electron microscopy (SEM) images and X-ray diffrac- tion (XRD), which are consistent with literature data. The Brunauer-Emmett-Teller (BET) surface area measurement shows that the MOFs samples have a high cover- age of nitrogen. The specific surface area of a typical MIL-101 (Cr) MOFs sample is 2716.83 m2/g. MIL-101 (Cr) also shows good uptake at low pressures in experimental tests for nitrogen adsorption. For the PETG substrate, disk-shape plastic samples with a controlled pore morphology were designed and fabricated using the fused de-</p><p> </p><p>position modeling (FDM) process. MOFs were coated on the PETG substrates using a layer-by-layer (LbL) assembly approach, up to 30 layers. The MOFs coating layer thicknesses increase with the number of deposition layers. The computational model illustrates that the MOFs show increased outputs in adsorption of nitrogen as pres- sure increases, similar to the trend observed in the adsorption experiment. The model also shows promising results for carbon dioxide uptake at low pressures, and hence the developed MOFs based components would serve as a viable candidate in gas adsorption applications.</p><div><br></div></div>
445

Implementing Additive Manufacturing in Cardiology : A qualitative study of barriers and facilitators from a managemental point of view

Sandgren, Simon, Wolff, Annette January 2020 (has links)
Additive Manufacturing (AM) is a fast-developing technology, that despite itspotential is yet to be applied by the mainstream healthcare market. Comparedto other clinical areas where AM is applied, cardiology has a negligible marketshare, why this thesis aimed at identifying barriers and facilitators for AMimplementation, as well as presenting a framework with factors to considerwhen attempting to implement AM. A literature review outlined aspects currently considered in literature, inrelation to the barriers and facilitators of implementing AM in cardiology. Toidentify barriers and facilitators to AM implementation in cardiology, and tocomplement the literature review, two exploratory case studies were carriedout, which had a comparative design. The case studies took place in Sweden,whereof one has already implemented AM in cardiology, and the other one hasnot. Purposive sampling was applied to choose the two involved hospitals, whileconvenience sampling and snowball sampling were used for selecting interviewparticipants. The findings were analyzed using a thematic analysis. Results show that barriers and facilitators can act on an individual,organizational, and industrial level. Barriers and facilitators were divided intothe themes Management, Technology, Network, Behavior, and Market. Aspectsfalling under the theme Management were mentioned most frequently amongthe respondents, suggesting that such barriers and facilitators play a significantrole in implementing AM, while findings placed in the Network and Behaviortheme respectively were not previously addressed in literature. Barriersinclude, among others, low involvement of leaders, little cross disciplinarycollaboration, and lack of innovation resources in health care. Facilitatorsinclude, among others, having an innovation culture that supports initiation ofprojects, providing an easy and intuitive system for ordering a 3D model, andpromoting the technology among potential users. Concluded is that AM implementation faces numerous barriers and facilitatorswhich should be considered before an implementation endeavor. Addressingthese on an individual, organizational, and industrial level most likely facilitatesthe process of AM implementation, leading to a successful and sustainablechange in the organization.
446

Multifunctional Testing Artifacts for Evaluation of 3D Printed Components by Fused Deposition Modeling

Pooladvand, Koohyar 19 November 2019 (has links)
The need for reliable and cost-effective testing procedures for Additive Manufacturing (AM) is growing. In this Dissertation, the development of a new computational-experimental method based on the realization of specific testing artifacts to address this need is presented. This research is focused on one of the widely utilized AM technologies, Fused Deposition Modeling (FDM), and can be extended to other AM technologies as well. In this method, testing artifacts are designed with simplified boundary conditions and computational domains that minimize uncertainties in the analyses. Testing artifacts are a combination of thin and thick cantilever structures, which allow measurement of natural frequencies, mode shapes, and dimensions as well as distortions and deformations. We apply Optical Non-Destructive Testing (ONDT) together with computational methods on the testing artifacts to predict their natural frequencies, thermal flow, mechanical properties, and distortions as a function of 3D printing parameters. The complementary application of experiments and simulations on 3D printed testing artifacts allows us to systematically investigate the density, porosity, moduli of elasticity, and Poisson’s ratios for both isotropic and orthotropic material properties to better understand relationships between these characteristics and the selected printing parameters. The method can also be adapted for distortions and residual stresses analyses. We optimally collect data using a design of experiments technique that is based on regression models, which yields statistically significant data with a reduced number of iterations. Analyses of variance of these data highlight the complexity and multifaceted effects of different process parameters and their influences on 3D printed part performance. We learned that the layer thickness is the most significant parameter that drives both density and elastic moduli. We also observed and defined the interactions among density, elastic moduli, and Poisson’s ratios with printing speed, extruder temperature, fan speed, bed temperature, and layer thickness quantitatively. This Dissertation also shows that by effectively combining ONDT and computational methods, it is possible to achieve greater understanding of the multiphysics that governs FDM. Such understanding can be used to estimate the physical and mechanical properties of 3D printed components, deliver part with improved quality, and minimize distortions and/or residual stresses to help realize functional components.
447

Energy Release Rate Characterization of Additively Manufactured Al/PVDF with Varying Infill Densities and Patterns

Alexander Charles Ca Hoganson (12879233) 16 June 2022 (has links)
<p>  </p> <p>The additive manufacturing of energetic materials is a novel way to alter the properties of an energetic material without necessarily changing its chemical structure. There are many methods of additive manufacturing which can be applied to energetic material fabrication, each of which have unique advantages and disadvantages. The most well characterized additive manufacturing method is the commercially refined technique of fused filament fabrication (FFF) printing. FFF manufacturing techniques can be applied to additively manufacture thermoplastic energetic materials. The thermoplastic aluminum and polyvinylidene difluoride (Al/PVDF) system is suitable for manufacture with FFF techniques, shapeable into pyrotechnics with custom geometries using commonly available FFF printers. This theoretically allows Al/PVDF systems to be tailored for a wide variety of multifunctional needs, such as reactive structures. Following a literature review describing energetic material additive manufacturing techniques, this thesis focuses on the creation of outwardly identical Al/PVDF samples and the use of a geometric correction factor to control for uneven feedstock diameter. By varying the infill pattern, infill density, and interior geometry, different sample energy densities were obtained and observed during combustion. High speed videography measurements and the mass of individual samples were used to estimate the overall energy release rate. An Ashby plot contrasting the energy density and energy release rate was obtained. While full density printed samples burned similar to cast propellant strands in a linear burn, the energy release rates of additively manufactured Al/PVDF could be increased via convective combustion by varying the infill type and density. These results have significance for the fields of structural energetic materials and for additive manufacturing studies of energetic materials.</p>
448

Fundamentals and Applications of Ion Mobility Using 3D Printed Devices

Robert Louis Schrader (11115012) 22 July 2021 (has links)
<p>Advancements in 3D printing technology have provided (1) easy access to low-cost, open- source robotics, and (2) a fast fabrication technique for analytical devices among others. Using the robotics of a 3D printer, a mass spectrometry-based reaction screening device was built as a low- cost, modest throughput alternative to expensive, very fast systems. Using the 3D printer for fabrication, ion mobility devices were fabricated. Fundamental studies of the motion of ions in these devices were performed in addition to applications of ion mobility-mass spectrometry using a 3D printed drift tube ion mobility spectrometer.</p><p><br></p><p>With only simple modification, 3D printer kits provide nearly all the necessary parts for a functional reaction screening device. Replacing the hotend assembly with custom parts to hold a syringe, precise volumes of reaction mixtures can be dispensed, and high voltage applied to the needle for direct analysis of solutions by mass spectrometry. Direct analysis of reaction mixtures in a 96-well microtiter plates was completed in approximately 105 minutes (~65 seconds per reaction mixture, including washing of syringe). Following analysis, product distributions derived from the electrospray mass spectra were represented as heatmaps and optimum reaction conditions were determined. Using low-cost, open-source hardware, a modest throughput for reaction screening could be achieved using electrospray ionization mass spectrometry.</p><p><br></p><p>The manipulation of ions at reduced pressures is very well understood, whereas the efficient manipulation of ions at atmospheric pressure is far less understood. Using 3D printing, multiple iterations of atmospheric pressure drift tube ion mobility spectrometers were fabricated with one and two turns in the drift path. Optimum electrode geometries for ion transmission and resolution were determined by both simulation and experiment. Racetrack effects, where ions on the inside of turns have a shorter path than ions on the outside, were determined to be highly detrimental to resolving power. Drift tubes with two turns in opposite directions (a chicane) corrected for racetrack effects and had only marginally poorer resolving power than a straight drift tube. Additionally, ion intensities were nearly identical between optimized straight and turned ion paths, showing that these manipulations can be done with high efficiency. The focusing of ions at reduced pressure using RF ion funnels at reduced pressure can have nearly 100 percent transmission. At atmospheric pressure, RF fields are not nearly as efficient at focusing ions. By using non-uniform DC fields at atmospheric pressure, ions can be focused, but not nearly to the extent as at reduced pressure.</p><p><br></p><div><div><div><p>The coupling of atmospheric pressure drift tube ion mobility with ion trap mass spectrometry is inefficient due to the mismatch in duty cycle between the two instruments. For this reason, increasing the amount of data collected from a single experiment is of high importance. Fourier transform ion mobility increases the duty cycle from less than 1% to 25%. When ions are fragmented in the mass spectrometer, they maintain the frequency characteristic of the precursor. Therefore, ions can be fragmented without isolation in the ion trap (reducing duty cycle further) and related precursors and product ions identified through their drift time. Two-dimensional tandem mass spectrometry is a method to collect all tandem mass spectrometry information in a single scan. When coupled with ion mobility, this data can be used to generate functional group- specific ion mobility spectra where ion intensity is measured along a precursor or neutral loss scan line. This was demonstrated for a lipid sample in which head-group specific ion mobility spectra were obtained using head-group specific precursor and neutral loss scan lines.</p></div></div></div>
449

Formulation and In-vitro Evaluation of FDM 3D Printed Tablet with different Drug Loading

Subah, Farhana Noor January 2021 (has links)
No description available.
450

Material Extrusion Additive Manufacturing of Binder-Coated Zirconia: Process, Comprehensive Characterizations, and Applications

Huang, Rui 05 May 2022 (has links)
No description available.

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