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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.
91

Hydrothermally carbonized wood as a component in biobased material for 3D-printing / Hydrotermiskt karboniserat trä som komponent i biobaserat material för 3D-printing

Hendeberg, Matilda January 2020 (has links)
Consumers put higher demands on low environmental impact from the products they use, and the materials they consist of. As a result, more research is being made on finding environmentally friendly production techniques and materials. Hydrothermal carbonization (HTC) is a relatively environmentally friendly method that has been used in this study. Cellulose and pine, the latter, one sample with and one without bark, were carbonized at 220 °C and 240 °C for two hours. This generated solid carbon products that could be used in composites with the biopolymer Polylactide (PLA). The composites were thereafter extruded as filaments and used for 3D printing. X-ray powder diffraction (XRD), Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) showed that HTC of all precursors generated an amorphous carbon material, with carbon microspheres and increased aromaticity. Three different composites were produced from PLA and 0.1 wt% of the solid carbon products from all three precursors carbonized at 240 °C. Composites were also made from PLA and 1 wt% non-carbonized pine with bark, and 1 wt% of pine with bark carbonized at 240 °C. Filaments were extruded from neat PLA, as well as the composites of 0.1 wt% carbonized cellulose and 0.1 wt% carbonized pine with bark mentioned above. The filaments were used to 3D print six dog bones per filament according to the ISO standard ISO 527-2 1BA. There was one instance of clogging for each filament from the composite materials, but it was easily solved. No mechanical tests could be performed, although the 3D printed models’ physical properties were visually observed, and no deficiencies were found. Both extrusion and 3D printing were successful. / Konsumenter ställer högre krav på att material och produkter de använder har liten påverkan på miljön. Till följd av detta lägger forskningen mer resurser på att hitta miljövänliga tillverkningsmetoder och material. Hydrotermisk karbonisering (HTC) är en relativt miljövänlig process som har använts i denna studie. Tall (ett prov med och ett utan bark) samt cellulosa karboniserades vid 220 °C och 240 °C i två timmar, för att på detta vis producera en fast kolprodukt som kunde användas i en komposit med biopolymeren Polylaktid (PLA). Kompositen extruderades sedan till filament som användes vid 3D printing. Röntgenpulverdiffraktion (XRD), Svepelektronmikroskopi (SEM) och Fourier-transform infraröd spektroskopi (FTIR) visade på att HTC hade genererat amorfa kolmaterial, med mikrosfärer och ökad aromaticitet från både cellulosa och båda tallproverna. Samtliga produkter från karbonisering vid 240 °C användes för att göra tre olika kompositer med vardera 0,1 vikt% kolmaterial. Kompositer tillverkades även från PLA och 1 vikt% tall med bark, samt 1 vikt% tall med bark karboniserad vid 240 °C. Filament extruderades av ren PLA samt ovan nämnda kompositer med 0.1 vikt% karboniserad cellulosa och 0.1 vikt% karboniserad tall med bark. Dessa användes vid 3D printing för att skriva ut sex hundben per filament, enligt ISO standarden ISO 527-2 1BA. Vid ett tillfälle för vardera av de två kompositerna täpptes mynningen till 3D skrivaren igen av partiklar i filamenten. Detta löstes dock enkelt. Mekaniska tester kunde tyvärr inte utföras på hundbenen, men inga fysiska brister beskådades på dem. Både extrudering och 3D printing var lyckade.
92

Automation of printed circuit board testing on a bed-of-nails testbench

Antonsson, Tobias January 2022 (has links)
Syntronic Research & Development AB both designs and performs tests of PCBs of differentkinds. At lower volumes, big parts of the test process are manual. This thesis examines oneway to automate the loading and unloading process with a cheap and simple solution so that itcan be profitable even at low volumes. If all parts of the process are automated manpower canbe freed, hence the cost of testing can be lowered, and tedious monotonous work can beavoided. Human error can also be removed from the equation, which could result in lessstochastic errors. The approach to automate the loading and unloading of test objects in this thesis is to design atwo-axis linear robot. This way the PCBs can be picked from incoming plates, placed in thetestbench, and then be placed in outgoing plates, as long as they are all in a straight line. To find weakness in the design a prototype was constructed on which tests were performed.These tests showed some areas on which improvements are needed before it can beconsidered a finished product. These improvements are discussed. The tests also showed that this approach can be made profitable, with some limitations. The cost savings are greatly dependable on how the other process are automated. There are both limitations on the setup of the test fixture used and, perhaps mainly, on how theother process are automated. This is also discussed. One challenge yet to overcome is how to make it easy to adapt and implement for a specifictest. When and if a robot based on this concept is implemented the setup time will by far be thelargest contributor to the cost.
93

Motorized tensioner systemfor prosthetic hands

Hardell, Felix, Tjomsland, Jonas January 2018 (has links)
Modern research in prosthetic devices and other assistivetechnologies are constantly pushing boundaries. Whilethe technology is impressive, it is still inaccessible for thegreater part of the people in need of it. Advanced devicesare often extremely expensive and require regularly maintenancefrom professionals. Enabling the Future is a globalnetwork of volunteers and was founded to face these problems.They design and 3D-print mechanical prosthetics forpeople in need all over the world.Most of the designs used by Enabling the Future are purelymechanical and do not implement motors. The purposeof this thesis was to take a new approach to the designand construction of low-cost motorized prosthetic hands.By distancing all the electronic components from the hand,including the motor, the project aimed to create a devicecompatible with all current designs of the Enabling the Futurecommunity.To conceptualize this approach a demonstrator was constructedand tested. It utilized a muscle sensor which allowedusers to control the hand by tightening their muscles.The distance between the electronic components andthe prosthetic hand measured approximately one and a halfmeters and still transfered enough force, from the motor tothe hand, to deliver an adequate grip strength. / Modern forskning inom protestillverkning och andrahandikapphjälpmedel gör kontinuerligt stora framsteg. Trotsatt tekniken är imponerade är den fortfarande otillgängligför den största del människor som behöver den. Avanceradehjälpmedel är ofta extremt dyra och kräver kontinuerligtunderhåll från yrkesverksamma. Enabling the Future,ett globalt nätverk av volontärer, grundades för att utmanadessa problem. De konstruerar och tillverkar 3D-skrivnamekaniska proteser för människor med behov över hela världen.De flesta konstruktioner som används av Enabling the Futureär helt mekaniska och använder inga motorer. Syftetmed detta kandidatexamensarbete var att med nya tillvägagångssättkonstruera en billig motoriserad handprotes.Genom att placera all elektronik på en distans från handen,inklusive motorn själv, var tanken att skapa ett systemsom är kompatibelt med de konstruktioner som Enablingthe Future använder.För att förverkliga detta konstruerades en prototyp somtestats. Prototypen använde sig av en muskelsensor somlät användaren kontrollera proteshanden genom att spännasin arm. Distansen mellan de elektriska komponenternaoch protesen var ungefär en och en halv meter, samtidigtsom tillräckligt stor kraft kunde transporteras för att stängahanden med ett tillräckligt grepp.
94

Imaging and Characterization of the Multi-scale Pore System of Microporous Carbonates

Hassan, Ahmed 11 1900 (has links)
Microporous carbonates host a significant portion of the remaining oil-in-place in the giant carbonate reservoirs of the Middle East. Improved understanding of petrophysical and multi-phase flow properties at the pore-scale is essential for the development of better oil recovery processes. These properties strongly depend on the 3D geometry and connectivity of the pore space. In this study, we harnessed the unique capabilities of fluorescence confocal laser scanning microscopy (CLSM) to capture both macroporosity and microporosity, down to 0.1 µm, to provide a more representative 3D representation of pore space compared to traditional methods. The experimental procedure developed was specifically designed to enable highresolution confocal 3D imaging of the pore space of carbonate systems. The protocol aims to render carbonates more "transparent" to CLSM by imaging etched epoxy pore casts of the sample and minimizing CLSM signal scattering. The resulting highquality 3D images of the multi-scale pore space allow more reliable petrophysical interpretation and prediction of transport properties. Additionally, we present a robust pore imaging approach that correlates 2D images produced by scanning electron microscopy (SEM) with the 3D models produced by CLSM that cover a range of scales, from millimeters in 3D to micrometers in 2D. For the first time, multi-color fluorescence confocal imaging was employed to characterize the geometric attributes of a porous medium. We foresee that the protocol developed in this study could be used as a standard protocol for obtaining high-quality 3D images of epoxy pore casts using confocal microscopy, and could contribute to improved characterization of micritic carbonate reservoirs and oil recovery methods. We also demonstrate the advantages of multi-scale and multi-color confocal images in realizing more accurate evaluations of petrophysical properties. Finally, we demonstrate that micro 3D printing (two-photon polymerization) can potentially be used to fabricate micromodels with sufficient resolution to capture the geometric attributes of micritic carbonates and that can replicate the inherent 3D interconnectivity between macro- and micro-pores.
95

Additive Manufacturing Filled Polymer Composites for Environmental Contaminants: Material Extrusion Processing, Structure and Performance

Kennedy, Alan James 18 December 2023 (has links)
Research interest in Additive Manufacturing (AM) as an enabling technology for customizable parts is rapidly expanding. While much AM research focus is on high performance feedstocks and process optimization to obtain parts with improved mechanical properties, interest in the environmental applications of AM has recently increased. The lower cost and greater accessibility AM is leading to novel environmental research solutions in wastewater treatment and toxicity reduction by capitalizing on the increased affordability and accessibility of 3D printing (3DP) technologies for customizable, high surface area structures. The novelty and focus of this dissertation is exploration of Material Extrusion (MatEx) based Fused Filament Fabrication (FFF) of filled polymer composites as a disruptive technology enabler for deployable and retrievable structures in environmental media for adsorption, destruction and toxicity reduction of harmful chemicals. This dissertation addresses research questions that generally answer, "why AM for environmental applications?". The inherent layer-by-layer design provides larger surface area structures for interaction with contaminated media. Polylactic acid (PLA) was selected due to its green sources and biocompatibility relative to synthetic polymers and its wide processing window allowing shear thinning and "printability" despite the elevated viscosity and modulus of highly filled composites. The filler selected for contaminant adsorption was microporous zeolite, which has affinity for ammonia, radionuclides and Per- and Polyfluorinated Substances (PFAS). The filler selected for contaminant destruction was photocatalytic TiO2 nanoparticles which can degrade organic chemicals, harmful algal bloom toxins and PFAS. A preliminary research hurdle was overcome by demonstrating that immobilization of zeolite and TiO2 in a PLA binder matrix did not prevent adsorption or free radical release, respectively. The first major research objective involved investigation of high surface area printed PLA-zeolite geometries with different zeolite loadings and found that while ammonia was reduced, there were diminishing returns with increased loading in terms of mass standardized adsorptive performance due to insufficiently exposed zeolite. The research solution leveraged AM print process parameters to increase the macroporosity of the printed composite structure to create voids and channels allowing water infiltration and chemical adsorption to zeolite. Faster printing of larger roadways generated macrostructural voids that were maintained by extrusion at lower temperature for rapid solidification. The second research objective involved compounding different loadings and dispersion states of TiO2 in PLA to demonstrate immobilization of TiO2 closer to UV-light penetration water improves photocatalysis. Higher 32% w/w TiO2 loadings were heavily agglomerated and more difficult to print process due to high viscosity, rapid liquid-solid transition (G'>G") and particle network recovery during printer retractions, leading to nozzle clogging. Lower 20% w/w loading was more conducive to larger production printing due to lower viscosity, longer viscosity recovery times for retractions and thus generally a wider processing window. While altering twin screw processing parameters reduced TiO2 agglomerates in filaments, leading to increases in crystallinity (due to seeding effects and chain scission) and lower viscosity recovery, photocatalytic performance was not significantly improved. Evidence presented showed that larger particle agglomerates were more toward the inside of printed surfaces and thus less available to UV-light irradiation. This location of larger particles is supported by previous theoretical and empirical investigations showing larger particles migrate at a faster velocity away from the outer walls of confined extrudates within non-Newtonian flow fields due to normal forces, leaving more smaller particles toward outer surfaces. This research provided novel contributions to the environmental and AM research communities and pioneered a convergence of these fields into an interdisciplinary community of practice focused on better characterization and processing in environmental applications to improve structure-environmental property relationships. Future research should build on these findings to enhance performance through multi-functional materials that adsorb and destroy contaminants. The reactive surface area should be further increased through by high surface area designs and print parameter optimized porous structures providing a continuum of meso- to microporosity as confirmed by chemical flux and mass transfer studies for additional AM technologies (e.g., Direct Ink Write). / Doctor of Philosophy / Engineers and hobbies alike have great interest in Additive Manufacturing (AM), or 3D Printing, to customize parts and new designs. More recently, environmental scientists and engineers have turned to 3D printing to solve environmental problems due to the lower cost and user-friendliness of desktop machines. This research dissertation focuses on how 3D printing can allow for iterative improvements in customizable, high surface area structures to reduce chemical concentrations in water by either adsorbing or destroying the chemicals. Water is clearly a critical resource for ecosystems, recreation and drinking supplies as national security, human and ecosystem health are tied to clean water. This research addresses why 3D printing is interesting and effective for environmental solutions. Briefly the layer-by-layer design provides larger surface area structures for interaction with contaminated media. The common 3D printer feedstock Polylactic Acid (PLA) was selected since it is non-toxic and can be relatively easy to print even if modified by adding rigid filler particles for research. Micron-scale (zeolite) and nano-scale (Titanium Dioxide) particles were mixed with the polymer to make printable filaments to adsorb and destroy contaminants, respectively. This research demonstrated the proof-of-concept by removing ammonia, methylene blue dye and a harmful algal toxin from water. The materials produced are also applicable to both conventional organic pollutants and emerging contaminants of concern in the popular news such as Per- and Polyfluorinated Substances (PFAS), which were used as flame retardants and non-stick surfaces. This research ties the material properties of the experimental micro- and nano-composite filaments to how the materials extrude and solidify during 3D printing and how well the resulting printed structures work for reducing contaminant levels in water. Altering the parameters and conditions at which these materials are processed and 3D printed can significantly change their structure, density, porosity and distribution of particles and in turn increase effectiveness. The results provide new contributions to both the environmental and AM research communities and pioneers interdisciplinary collaborative ideas for these different subject matter experts to work together to better understand how handling and processing of these materials can improve their performance in environmental applications. New work should leverage the ideas and principles presented here to further improve performance, ease of production and scale-up of multifunctional material structures for multiple classes of chemicals that are of concern in surface and drinking water.
96

3D PRINTING TO CONTROL DRUG RELEASE FROM KERATIN HYDROGELS

Brodin, Erik W., V 17 July 2018 (has links)
No description available.
97

Topological (Bio)Timber: An Algorithm and Data Approach to 3d Printing a Bioplastic and Wood Architecture

Macias, Diego 29 September 2017 (has links)
No description available.
98

Properties of 3D Printed Continuous Fiber-Reinforced CNTs and Graphene Filled Nylon 6 Nanocomposites

Liu, Zhihui January 2017 (has links)
No description available.
99

The Development of 3D Printable Materials

Bootsma, Katherine Jean 02 December 2016 (has links)
No description available.
100

Cellulose and polypropylene filament for 3D printing / Cellulosa och polypropen filament för 3D-utskrivning

Kwan, Isabella January 2016 (has links)
Additive manufacturing has become a very popular and well mentioned technique in recent years. The technique, where 3 dimensional (3D) printing is included, creates opportunities to develop new designs and processing systems. As a research institute within the forest based processes and products, Innventia AB has an idea of combining 3D printing with cellulose. The addition of cellulose will increase the proportion of renewable raw material contributing to more sustainable products. However, when cellulose is added the composition of the filaments changes. The main aim for the project is to devise methodologies to improve properties of composite filaments used for 3D printing. Filament in 3D printing refers to a thread-like object made of different materials, such as PLA and ABS, that is used for printing processes. A literature study was combined with an extensive experimental study including extrusion, 3D printing and a new technique that was tested including 3D scanning for comparing the printed models with each other. The extruding material consisted of polypropylene and cellulose at different ratios, and filaments were produced for 3D printing. The important parameters for extruding the material in question was recorded. Because the commingled material (PPC) was in limited amount, UPM Formi granulates, consisting of the same substances, was used first in both the extrusion and printing process. Pure polypropylene filaments were also created in order to strengthen the fact that polypropylene is dimensional unstable and by the addition of cellulose, the dimensional instability will decrease. After producing filaments, simple 3D models were designed and printed using a 3D printing machine from Ultimaker. Before starting to print, the 3D model needed to be translated into layer-by-layer data with a software named Cura. Many parameters were vital during printing with pure polypropylene, UPM and PPC. These parameters were varied during the attempts and marked down for later studies. With the new technique, in which 3D scanning was included, the 3D printed models were compared with the original model in Cura in order to overlook the deformation and shape difference. The 3D scanner used was from Matter and Form. Photographs of the printed models, results from the 3D scanner, and screenshots on the model in Cura were meshed together, in different angles, using a free application named PicsArt. The result and conclusion obtained from all three parts of the experimental study was that polypropylene’s dimensional stability was improved after the addition of cellulose, and the 3D printed models’ deformation greatly decreased. However, the brittleness increased with the increased ratio of cellulose in the filaments and 3D models. / Additiv tillverkning har på den senare tiden blivit en mycket populär och omtalad teknik. Tekniken, där tredimensionell (3D) utskrivning ingår, ger möjligheter att skapa ny design och framställningstekniker. Som ett forskningsinstitut inom massa- och pappersindustrin har Innventia AB en ny idé om att kombinera 3D-utskrivning med cellulosa. Detta för att höja andelen förnybar råvara som leder till mer hållbara produkter. Dock kommer filamentens sammansättning vid tillsättning av cellulosa att ändras. Det främsta syftet med detta projekt är att hitta metoder för att förbättra egenskaperna hos de kompositfilament som används för 3D-utskrifter. Filament inom 3D-utskrivning är det trådlika objektet gjort av olika material, såsom PLA och ABS, som används vid utskrivningsprocessen. En enkel litteraturstudie kombinerades med en experimentell studie. Det experimentella arbetet var i fokus i detta projekt som omfattade extrudering, 3D-utskrivning samt en ny teknik som prövades, där 3D-scanning ingick, för att jämföra de utskrivna modellerna med varandra. Extruderingsmaterialet bestod av polypropen och cellulosa av olika halter, och av detta material tillverkades filament för 3D-utskrivning. De viktiga parametrarna för extrudering med det önskade materialet antecknades. Eftersom mängden cominglat material (PPC) var begränsat, användes först UPM Formi granuler, som består av samma substanser som i PPC, i både extruderingen och utskrivningen. Filament av ren polypropen tillverkades också för att stärka det faktum att polypropen är dimensionellt instabil. Genom att tillsätta cellulosa minskades dimensionsinstabiliteten. Efter att filamenten hade tillverkats, designades enkla 3D-modeller för utskrivning med en 3D-utskrivare från Ultimaker. Innan utskrivningen kunde börja behövde 3D-modellen bli översatt till lager-på-lager-data med hjälp av en programvara vid namn Cura. Många parametrar är viktiga vid utskrivning med ren polypropen, UPM samt PPC. Temperatur och hastighet varierades för de olika försöken och antecknades för senare studier.Med den nya tekniken, där 3D-scanning ingår, jämfördes de utskrivna 3D-modellerna med originalmodellen i Cura för att se över deformationen och formskillnaden. Den 3D-scanner som användes kom från Matter and Form. Fotografier på de utskrivna modellerna, resultaten från 3D-scannern och bilder på modellerna i Cura sammanfogades i olika vinklar med hjälp av ett gratisprogram som heter PicsArt. Det resultat som erhölls och den slutsats som kunde dras utifrån alla tre delarna av den experimentella studien var att polypropens dimensionsinstabilitet minskades efter tillsatsen av cellulosa, och att de 3D-utskrivna modellernas deformation minskade kraftigt. Skörheten ökade ju högre halt cellulosa som filamenten och de utskrivna modellerna innehöll.

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