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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.
381

Optische Materialien für die Additive Fertigung / Optical materials for additive manufacturing

Klein, Matthias January 2022 (has links) (PDF)
In der vorliegenden Arbeit wurden neue Materialien für die additive Fertigung für opti-sche Anwendungen entwickelt. Hierbei wurde zunächst ein ORMOCER® Harz für den LCD/DLP 3D-Druck synthetisiert und charakterisiert. Das Material zeigte eine gute Druckbarkeit, gute optische Eigenschaften und eine hohe Stabilität gegenüber Belas-tungen mit UV-Licht, Temperatur und Luftfeuchtigkeit. Die prozessbedingte Stufenbil-dung für gekrümmte Oberflächen beim LDC/DLP Druck erforderte eine Weiterentwick-lung zu einem Harz, das auch mittels Inkjet-Verfahren gedruckt werden kann. Hierfür mussten die Viskosität des ORMOCER®s und die Einflüsse darauf untersucht werden. Zu diesem Zweck wurde die Synthese entsprechend verändert und die Produkte cha-rakterisiert. Variationen des Wasseranteils, des Katalysators, der Reaktionszeit, der Re-aktionsführung und der Edukte wurden durchgeführt. Harze mit resultierender niedriger Viskosität dürfen zusammenfassend nur zweifach anorganisch vernetzende Edukte mit niedrigem Reibungskoeffizienten beinhalten. Ein H2O-Verhältnis von 0,5 zu den vorlie-genden Si-O-Gruppen resultiert in akzeptablen Viskositäten und einer ausreichenden Stabilität. Als zuverlässiger Katalysator stellte sich HCl heraus. Die Reaktionszeit muss so gewählt werden, dass die Sol-Gel-Synthese abgeschlossen ist. Kürzere Zeiten füh-ren zwar zu kleineren Viskositäten, jedoch auch zu eventuell schlechter Langzeitstabili-tät. Veränderungen in der Reaktionsführung, durch Zutropfen der Edukte, resultierten jedoch vorwiegend zur Erhöhung der Viskositäten. Mit diesen Erkenntnissen wurde an-schließend ein Harz synthetisiert, das erfolgreich ohne weitere Verdünnungsschritte am Inkjet-Drucker prozessiert werden konnte. Dieses Harz ist zusätzlich auch am LCD/DLP Drucker einsetzbar. Als ergänzender Schritt konnte im Anschluss noch gezeigt werden, dass Partikel in Harze zusätzliche Eigenschaften, wie Fluoreszenz, einbringen können. / In the present work, new materials for additive manufacturing for optical applications were developed. First, an ORMOCER® resin for LCD/DLP 3D printing was synthe-sized and characterized. The material showed good printability, good optical proper-ties and high stability against exposure to UV light, temperature and humidity. The process-related step formation for curved surfaces in LDC/DLP printing required fur-ther development of a resin that can also be printed by inkjet. For this purpose, the variables of the viscosity of ORMOCER®s had to be investigated. For this purpose, the synthesis was modified accordingly, and the products were characterized. Varia-tions of the water content, the catalyst, the reaction time, the way of the reaction and the reactants were carried out. In summary, resins with resulting low viscosity may contain only twofold inorganic crosslinking reactants with low friction coefficient. An H2O ratio of 0.5 to the Si-O groups present results in acceptable viscosities and suffi-cient stability. HCl turned out to be a reliable catalyst. The reaction time must be as long as the sol-gel synthesis needs to be completed. Shorter times lead to lower vis-cosities, but also to possibly poor long-term stability. However, changes in the reaction control, for example by adding reactants dropwise, resulted mainly in an increase in viscosity. These findings were then used to synthesize a resin that could be success-fully processed on the inkjet printer without further dilution steps. This resin can also be used on the LCD/DLP printer. As a complementary step, it was subsequently shown that particles can introduce additional properties, such as fluorescence, into resins. Here, quantum dots, black dyes and refractive index-increasing zirconium dioxide particles were successfully incorporated into LCD/DLP resins and characterized.
382

Development and Analysis of 3D-Printed Synthetic Vocal Fold Models

Romero, Ryan Gregory 01 August 2019 (has links)
Vocal fold models are valuable for studying voice production. They provide an alternative method of studying the mechanics of the voice that does not require in vivo experimentation or the use of excised human or animal tissue. In this thesis, a new method of creating vocal fold models through additive manufacturing is described. The purpose of this research was to reduce model fabrication time, to decrease the number of model failures during manufacturing, and to lay the foundation for creating models with more lifelike geometric and material properties. This research was conducted in four stages. First, a suitable silicone additive manufacturing technique using a UV-curable silicone was chosen. The technique chosen was called freeform reversible embedding (FRE) and involved embedding liquid silicone material into a gel-like medium named organogel. The UV-curable silicone's material properties were identified to confirm its utility in vocal fold model design. Second, an open-source, fused deposition modeling slicing software was selected to create g-code for the printer. Applicable software settings were tuned through qualitative printing tests to find their optimal values for use in FRE printing. Third, 3D-printed cubes were used in tensile tests to characterize the material properties of FRE-printed, silicone material. The cubes were found to be anisotropic, exhibiting different modulus values corresponding to the layer orientation of the printed material. Fourth, vocal fold models were FRE-printed in two different layer orientations and were used in phonation tests to gather data for onset pressure, vibratory frequency, amplitude, and flow rate. The printed models self-oscillated and withstood the strains induced by phonation. These tests showed that layer direction affects the phonation properties of the models, demonstrating that models with layers in the coronal plane had slightly lower frequencies and onset pressures than models with layers in the sagittal plane. The models' onset pressures were higher than what is found in human vocal folds. However, their frequencies were within a comparable range. These tests showed the effectiveness of additive manufacturing in the application of vocal fold fabrication, reducing production effort by allowing researchers to go directly from model design to fabrication in a single manufacturing step. It is anticipated that this method will be modified to incorporate printing of multiple stiffnesses of silicone to better mimic the material properties of vocal fold tissue, and that the anisotropy of 3D-printed material will be leveraged to model the anisotropy of human vocal folds. This work also has potential application areas outside of voice research.
383

Additive Manufactured Material

Ek, Kristofer January 2014 (has links)
This project treats Additive Manufacturing (AM) for metallic material and the question if it is suitable to be used in the aeronautics industry. AM is a relatively new production method where objects are built up layer by layer from a computer model. The art of AM allows in many cases more design freedoms that enables production of more weight optimized and functional articles. Other advantages are material savings and shorter lead times which have a large economic value. An extensive literature study has been made to evaluate all techniques on the market and characterize what separates the different processes. Also machine performance and material quality is evaluated, and advantages and disadvantages are listed for each technique. The techniques are widely separated in powder bed processes and material deposition processes. The powder bed techniques allow more design freedom while the material deposition techniques allow production of large articles. The most common energy source is laser that gives a harder and more brittle material than the alternative energy sources electron beam and electric arc. Two specific techniques have been selected to investigate further in this project. Electron Beam Melting (EBM) from Arcam and Wire fed plasma arc direct metal deposition from Norsk Titanium (NTiC). EBM is a powder bed process that can manufacture finished articles in limited size when no requirements are set on tolerances and surface roughness. NTiC uses a material deposition process with electric arc to melt wire material to a near-net shape. The latter method is very fast and can produce large articles, but have to be machined to finished shape. A material investigation have been made where Ti6Al4V-material from both techniques have been investigated in microscope and tested for hardness. For the EBM-material have also surface roughness and weldability been investigated since the limited building volume often requires welding. The materials have mechanical properties better than cast material with respect to strength and ductility, but not as good as wrought material. Test results show that the difference in mechanical properties in different directions is small, even though the material has an inhomogeneous macrostructure with columnar grains in the building direction. The EBM-material has a finer microstructure and a stronger material and, in combination with improved design freedom, this technique is most suitable for aerospace articles when the weldability is good and it is possible to surface work where requirements of the surface roughness are set. Keywords: Additive Manufacturing, Aeronautics, Titanium / Det här projektet behandlar området Additiv Tillverkning (AM) för metalliska material och undersöker om det är lämpligt att använda vid produktion inom flygindustrin. AM är en relativt ny tillverkningsmetod där föremål byggs upp lager för lager direkt ifrån en datormodell. Teknikområdet tillåter i många fall större konstruktionsfriheter som möjliggör tillverkning av mer viktoptimerade och funktionella artiklar. Andra fördelar är materialbesparing och kortare ledtider vilket har ett stort ekonomiskt värde. En omfattande litteraturstudie har gjorts för att utvärdera alla tekniker som finns på marknaden och karakterisera vad som skiljer de olika processerna. Även maskiners prestanda och kvalité på tillverkat material utvärderas, och för varje teknik listas möjligheter och begränsningar. Teknikerna delas grovt upp i pulverbäddsprocesser och material deposition-processer. Pulverbäddsteknikerna tillåter större friheter i konstruktion, medan material deposition-processerna tillåter tillverkning av större artiklar. Den vanligaste energikällan är laser som ger ett starkare men mer sprött material än de alternativa energikällorna elektronstråle och ljusbåge. Två specifika tekniker har valts ut för att undersöka närmare i detta projekt. Electron Beam Melting (EBM) från Arcam och Wire fed plasma arc direct metal deposition från Norsk Titanium (NTiC). EBM är en pulverbäddsprocess som kan tillverka färdiga artiklar i begränsad storlek då låga krav ställs på toleranser och ytfinhet. NTiC använder en material deposition-process med en ljusbåge för att smälta ner trådmaterial till en nära färdig artikel. Den senare metoden är mycket snabb och kan tillverka stora artiklar, men måste maskinbearbetas till slutgiltig form. En materialundersökning har genomförts där Ti6Al4V-material från båda teknikerna har undersökts i mikroskop och testats för hårdhet. För EBM-material har även ytfinhet och svetsbarhet undersökts då begränsad byggvolym i många fall kräver fogning. Materialen har egenskaper bättre än gjutet material med avseende på styrka och duktilitet, men inte lika bra som valsat material. Provning visar att skillnaden på mekaniska egenskaper i olika riktningar är liten även fast materialet har en inhomogen makrostruktur med kolumnära korn i byggriktningen. EBM ger en finare mikrostruktur och ett starkare material och, tillsammans med de ökade konstruktionsfriheterna, så är det den tekniken som är bäst lämpad för flygplansartiklar då svetsbarheten är god och det finns möjlighet att bearbeta ytan till slutgiltigt krav. Nyckelord: Additiv Tillverkning, Flygteknik, Titan
384

Additivt tillverkat material / Additive manufactured material

Ek, Kristofer January 2014 (has links)
SammanfattningDet här projektet behandlar området Additiv Tillverkning (AM) för metalliska material och undersöker om det är lämpligt att använda vid produktion inom flygindustrin. AM är en relativt ny tillverkningsmetod där föremål byggs upp lager för lager direkt ifrån en datormodell. Teknikområdet tillåter i många fall större konstruktionsfriheter som möjliggör tillverkning av mer viktoptimerade och funktionella artiklar. Andra fördelar är materialbesparing och kortare ledtider vilket har ett stort ekonomiskt värde.En omfattande litteraturstudie har gjorts för att utvärdera alla tekniker som finns på marknaden och karakterisera vad som skiljer de olika processerna. Även maskiners prestanda och kvalité på tillverkat material utvärderas, och för varje teknik listas möjligheter och begränsningar. Teknikerna delas grovt upp i pulverbäddsprocesser och material deposition-processer. Pulverbäddsteknikerna tillåter större friheter i konstruktion, medan material deposition-processerna tillåter tillverkning av större artiklar. Den vanligaste energikällan är laser som ger ett starkare men mer sprött material än de alternativa energikällorna elektronstråle och ljusbåge.Två specifika tekniker har valts ut för att undersöka närmare i detta projekt. Electron Beam Melting (EBM) från Arcam och Wire fed plasma arc direct metal deposition från Norsk Titanium (NTiC). EBM är en pulverbäddsprocess som kan tillverka färdiga artiklar i begränsad storlek då låga krav ställs på toleranser och ytfinhet. NTiC använder en material deposition-process med en ljusbåge för att smälta ner trådmaterial till en nära färdig artikel. Den senare metoden är mycket snabb och kan tillverka stora artiklar, men måste maskinbearbetas till slutgiltig form. En materialundersökning har genomförts där Ti6Al4V-material från båda teknikerna har undersökts i mikroskop och testats för hårdhet. För EBM-material har även ytfinhet och svetsbarhet undersökts då begränsad byggvolym i många fall kräver fogning. Materialen har egenskaper bättre än gjutet material med avseende på styrka och duktilitet, men inte lika bra som valsat material. Provning visar att skillnaden på mekaniska egenskaper i olika riktningar är liten även fast materialet har en inhomogen makrostruktur med kolumnära korn i byggriktningen. EBM ger en finare mikrostruktur och ett starkare material och, tillsammans med de ökade konstruktionsfriheterna, så är det den tekniken som är bäst lämpad för flygplansartiklar då svetsbarheten är god och det finns möjlighet att bearbeta ytan till slutgiltigt krav.Nyckelord: Additiv Tillverkning, Flygteknik, Titan / AbstractThis project treats Additive Manufacturing (AM) for metallic material and the question if it is suitable to be used in the aeronautics industry. AM is a relatively new production method where objects are built up layer by layer from a computer model. The art of AM allows in many cases more design freedoms that enables production of more weight optimized and functional articles. Other advantages are material savings and shorter lead times which have a large economic value.An extensive literature study has been made to evaluate all techniques on the market and characterize what separates the different processes. Also machine performance and material quality is evaluated, and advantages and disadvantages are listed for each technique. The techniques are widely separated in powder bed processes and material deposition processes. The powder bed techniques allow more design freedom while the material deposition techniques allow production of large articles. The most common energy source is laser that gives a harder and more brittle material than the alternative energy sources electron beam and electric arc.Two specific techniques have been selected to investigate further in this project. Electron Beam Melting (EBM) from Arcam and Wire fed plasma arc direct metal deposition from Norsk Titanium (NTiC). EBM is a powder bed process that can manufacture finished articles in limited size when no requirements are set on tolerances and surface roughness. NTiC uses a material deposition process with electric arc to melt wire material to a near-net shape. The latter method is very fast and can produce large articles, but have to be machined to finished shape. A material investigation have been made where Ti6Al4V-material from both techniques have been investigated in microscope and tested for hardness. For the EBM-material have also surface roughness and weldability been investigated since the limited building volume often requires welding. The materials have mechanical properties better than cast material with respect to strength and ductility, but not as good as wrought material. Test results show that the difference in mechanical properties in different directions is small, even though the material has an inhomogeneous macrostructure with columnar grains in the building direction. The EBM-material has a finer microstructure and a stronger material and, in combination with improved design freedom, this technique is most suitable for aerospace articles when the weldability is good and it is possible to surface work where requirements of the surface roughness are set.Keywords: Additive Manufacturing, Aeronautics, Titanium
385

ADDITIVE MANUFACTURING TECHNOLOGIES FOR FLEXIBLE OPTICAL AND BIOMEDICAL SYSTEMS

Bongjoong Kim (10716684) 28 April 2021 (has links)
<p>Advances in additive manufacturing technologies enable the rapid, high-throughput generation of mechanically soft microelectromechanical devices with tailored designs for many applications spanning from optical to biomedical applications. These devices can be softly interfaced with biological tissues and mechanically fragile systems, which enables to open up a whole new range of applications. However, the scalable production of these devices faces a significant challenge due to the complexity of the microfabrication process and the intolerable thermal, chemical, and mechanical conditions of their flexible polymeric substrates. To overcome these limitations, I have developed a set of advanced additive manufacturing technologies enabling (1) mechanics-driven manufacturing of quasi-three-dimensional (quasi-3D) nanoarchitectures with arbitrary substrate materials and structures; (2) repetitive replication of quasi-3D nanoarchitectures for infrared (IR) bandpass filtering; (3) electrochemical reaction-driven delamination of thin-film electronics over wafer-scale; (4) rapid custom printing of soft poroelastic materials for biomedical applications. </p> <p>First, I have developed a new mechanics-driven nanomanufacturing method enabling large-scale production of quasi-3D plasmonic nanoarchitectures that are capable of controlling light at nanoscale length. This method aims to eliminate the need for repetitive uses of conventional nanolithography techniques that are time- and cost-consuming. This approach is innovative and impactful because, unlike any of the conventional manufacturing methods, the entire process requires no chemical, thermal, and mechanical treatments, enabling a large extension of types of receiver substrate to nearly arbitrary materials and structures. Pilot deterministic assembly of quasi-3D plasmonic nanoarrays with imaging sensors yields the most important advances, leading to improvements in a broad range of imaging systems. Comprehensive experimental and computational studies were performed to understand the underlying mechanism of this new manufacturing technique and thereby provide a generalizable technical guideline to the manufacturing society. The constituent quasi-3D nanoarchitectures achieved by this manufacturing technology can broaden considerations further downscaled plasmonic metamaterials suggest directions for future research.</p> <p>Second, I have developed mechanics-driven nanomanufacturing that provides the capability to repetitively replicate quasi-3D plasmonic nanoarchitectures even with the presence of an extremely brittle infrared-transparent spacer, such as SU-8, thereby manipulating IR light (e.g., selectively transmitting a portion of the IR spectrum while rejecting all other wavelengths). Comprehensive experimental and computational studies were performed to understand the underlying nanomanufacturing mechanism of quasi-3D plasmonic nanoarchitectures. The spectral features such as the shape of the transmission spectrum, peak transmission and full width at half maximum (FWHM), etc. were studied to demonstrate the bandpass filtering effect of the assembled quasi-3D plasmonic nanoarchitecture.</p> <p>Third, I have developed an electrochemical reaction-driven transfer printing method enabling a one-step debonding of large-scale thin-film devices. Conventional transfer printing methods have critical limitations associated with an efficient and intact separation process for flexible 3D plasmonic nanoarchitectures or bio-integrated electronics at a large scale. The one-step electrochemical reaction-driven method provides rapid delamination of large-scale quasi-3D plasmonic nanoarchitectures or bio-integrated electronics within a few minutes without any physical contact, enabling transfer onto the target substrate without any defects and damages. This manufacturing technology enables the rapid construction of quasi-3D plasmonic nanoarchitectures and bio-integrated electronics at a large scale, providing a new generation of numerous state-of-art optical and electronic systems.</p> <p>Lastly, I have developed a new printing method enabling the direct ink writing (DIW) of multidimensional functional materials in an arbitrary shape and size to rapidly prototype stretchable biosensors with tailored designs to meet the requirement of adapting the geometric nonlinearity of a specific biological site in the human body. Herein, we report a new class of a poroelastic silicone composite that is exceptionally soft and insensitive to mechanical strain without generating significant hysteresis, which yields a robust integration with living tissues, thereby enabling both a high-fidelity recording of spatiotemporal electrophysiological activity and real-time ultrasound imaging for visual feedback. Comprehensive <i>in vitro</i>, <i>ex vivo</i>, and <i>in vivo</i> studies provide not only to understand the structure-property-performance relationships of the biosensor but also to evaluate infarct features in a murine acute myocardial infarction model. These features show a potential clinical utility in the simultaneous intraoperative recording and imaging on the epicardial surface, which may guide a definitive surgical treatment.</p>
386

Only a Shadow : Industrial computed tomography investigation, and method development, concerning complex material systems

Jansson, Anton January 2016 (has links)
The complexity of components fabricated in today's industry is ever increasing. This increase is partly due to market pressure but it is also a result from progress in fabrication technologies that opens up new possibilities. The increased use of additive manufacturing and multi-material systems, especially, has driven the complexity of parts to new heights. The new complex material systems brings benefits in many areas such as; mechanical properties, weight optimisation, and sustainability. However, the increased complexity also makes material integrity investigations and dimensional control more difficult. In additive manufacturing, for example, internal features can be fabricated which cannot be seen or measured with conventional tools. There is thus a need for non-destructive inspection methods that can measure these geometries. Such a method is X-ray computed tomography. Computed tomography utilizes the X-rays ability to penetrate material to create 3D digital volumes of components. Measurements and material investigations can be performed in these volumes without any damage to the investigated component. However, computed tomography in material science is still not a fully mature method and there are many uncertainties associated with the investigation technique. In the work presented in this thesis geometries fabricated by various additive manufacturing processes have been investigated using computed tomography. Also in this work, a dual-energy computed tomography tool has been developed with the aim to increase the measurement consistency of computed tomography when investigating complex geometries and material combinations. / MultiMatCT
387

DETECTION AND SEGMENTATION OF DEFECTS IN X-RAY COMPUTED TOMOGRAPHY IMAGE SLICES OF ADDITIVELY MANUFACTURED COMPONENT USING DEEP LEARNING

Acharya, Pradip 01 June 2021 (has links)
Additive manufacturing (AM) allows building complex shapes with high accuracy. The X-ray Computed Tomography (XCT) is one of the promising non-destructive evaluation techniques for the evaluation of subsurface defects in an additively manufactured component. Automatic defect detection and segmentation methods can assist part inspection for quality control. However, automatic detection and segmentation of defects in XCT data of AM possess challenges due to contrast, size, and appearance of defects. In this research different deep learning techniques have been applied on publicly available XCT image datasets of additively manufactured cobalt chrome samples produced by the National Institute of Standards and Technology (NIST). To assist the data labeling image processing techniques were applied which are median filtering, auto local thresholding using Bernsen’s algorithm, and contour detection. A convolutional neural network (CNN) based state-of-art object algorithm YOLOv5 was applied for defect detection. Defect segmentation in XCT slices was successfully achieved applying U-Net, a CNN-based network originally developed for biomedical image segmentation. Three different variants of YOLOv5 which are YOLOv5s, YOLOv5m, and YOLOV5l were implemented in this study. YOLOv5s achieved defect detection mean average precision (mAP) of 88.45 % at an intersection over union (IoU) threshold of 0.5. And mAP of 57.78% at IoU threshold 0.5 to 0.95 using YOLOv5M was achieved. Additionally, defect detection recall of 87.65% was achieved using YOLOv5s, whereas a precision of 71.61 % was found using YOLOv5l. YOLOv5 and U-Net show promising results for defect detection and segmentation respectively. Thus, it is found that deep learning techniques can improve the automatic defect detection and segmentation in XCT data of AM.
388

Additiv tillverkning - En undersökning av processbyte från traditionella tillverkningsmetoder

Slessarevich, Daniel, Björk Ljunggren, Daniel January 2021 (has links)
The conventional manufacturing methods, such as milling and turning, are reliable methods which makes them commonly used. These methods are capable of producing high precision details with high surface quality. But there are drawbacks and limitations. Many of these methods are expensive and require high production volume to be profitable. The design constraints for conventional manufacturing methods are usually determined by the machining tools, which restrict shape and form.Additive manufacturing methods have gained high attraction in the last decades as an alternative to conventional methods. With greater design freedom, ease to use interface and minimal material waste, cost and time usage can be minimized. But changing the production process requires high knowledge of capability and limitations for these methods. This step is critical to assure the right detail and quality requirements. Additive manufacturing at present is limited to material selection, low precision and possibility of reduced mechanical properties. This report aims to investigate additive manufacturing and the possibility of replacing conventional manufacturing of tools and products. / De traditionella tillverkningsmetoderna (TT), exempelvis fräsning eller svarvning, är något många företag använder sig av för att bearbeta fram sina produkter. Dessa processer ger hög precision, snäva toleranser och en god ytfinish vid tillverkning. Men som för alla processer finns även nackdelar och begränsningar. Många av dessa processer är väldigt dyra och kräver större tillverkningsvolymer för att bli lönsamma. De har även begränsningar i frihet vid formgivning och kräver bland annat större kunskap hos operatören och leder till materialspill. På senare tid har additiva tillverkningsmetoder (AT) lockat många tillverkare för att byta ut de traditionella processerna. Med sin frihet i formgivning, enkelhet och diversitet ser man potential i att spara både tid och pengar. Men att byta ut nuvarande produktionsmetod kräver god förståelse av den nya metodens kapacitet och begränsningar. Detta för att kunna säkerställa kvalitetskrav för det tänkta arbetet. AT i dagens läge är begränsad till materialval, ger långt ifrån de snäva toleranser som kan åstadkommas med traditionella tillverkningsmetoderna, och kan påverka de mekaniska egenskaperna hos den tillverkade detaljen negativt. Vissa AT metoder kräver dessutom höga investeringskostnader och det visar sig inte alltid vara mer lönsamt mot traditionella tillverkningsmetoder. I detta arbete ska just detta undersökas och huruvida AT kan konkurrera med traditionella tillverkningsmetoder, samt hur AT kan säkerställa de krav som finns på befintlig produktion av detaljer. Detta arbete är en förstudie om additiv tillverkning och dess möjligheter att ersätta befintlig produktion av verktyg och produkter.
389

Design, Development and Optimization of A Flexible Nanocomposite Proximity Sensor

Reza Moheimani (12463587) 27 April 2022 (has links)
<p>  </p> <p>Sensing systems have evolved significantly in recent years as a result of several advances in a number of sensor manufacturing approaches. The proximity measuring of approaching objects is a challenging, costly, and critical operation that permits the detection of any impediments without coming into touch with them and causing an unfavorable occurrence. However, developing a flexible proximity sensor capable of operating throughout a wide range of object motion continues to be a difficulty. The current work describes a polymer-based sensor that makes use of a nanostructure composite as the sensing element. The sensor will be used in healthcare and automotive applications in the near future. Composites comprising Thermoplastic Polyurethane (TPU) and Carbon Nanotubes (CNTs) are capable of sensing the presence of an external item at a great distance. The sensor model's performance was then enhanced further by microfabricating an integrated model with a certain shape. The design and production techniques for the TPU/CNTs proximity sensor are basic, and the sensor's performance demonstrates repeatability, as well as high electrical sensitivity and mechanical flexibility. The sensing process is based on the comparison of stored charges at the composite film sensor to the sensor's base voltage. The sensor operates reliably across a detection range of 2-20 cm. Tunneling and fringing effects are used to explain substantial capacitance shifts as sensing mechanisms. The structure's fringing capacitance effect has been thoroughly examined using ANSYS Maxwell (Ansoft) FEA simulation, as the measurements perfectly confirm the simulation's sensitivity trend. A novel mathematical model of fringe capacitance and subsequent tests demonstrate that the distance between an item and the sensor may be determined. Additionally, the model argues that the change in capacitance is significantly influenced by sensor resistivity, with the starting capacitance varying between 0.045pF and 0.024pF in the range 103-105 mm. This analytical model would enable the sensor's sensitivity to be optimized.</p> <p>Additionally, a new generation of durable elastomeric materials is commercially accessible for 3D printing, allowing the development of an entirely new class of materials for wearable and industrial applications. By using functional grading and adjusting to diverse users, the mechanical reaction of soft 3D-printed objects may now be modified for increased safety and comfort. Additionally, electronics may be included into these 3D printed lattice and wearable structures to offer input on the movement of objects associated with healthcare devices as well as automotive components. Thus, in order to investigate the influence of additive manufacturing on the sensitivity of TPU/CNT sensors, samples with equal thickness and size but varied orientations are printed and compared to hot-press samples. Among the many 3D printed patterns, the [0,0] direction has the highest sensitivity, and may be used as an optimum method for increased sensitivity. In contrast to the hot-press samples, the 3D-printed TPU/CNT film features a crystalline network, which may aid in the passage of surface charges and hence increase capacitance changes.</p> <p>To have a better understanding which feature, and parameter can give us the most sensitivity we need to do an optimization. This will be accomplished by collecting experimental and computational results and using them as a basis for establishing a computationally and experimentally supported Genetic Algorithm Assisted Machine Learning (GAML) framework combined with artificial neural network (ANN) to develop TPU/CNT nanocomposite flexible sensors in which material characterizations will be coupled to strain, tactile, electronic and proximity characteristics to probe intermolecular interactions between CNTs and polymers. The proposed framework provides enhanced predictive capabilities by managing multiple sets of data gathered from physical testing (material characterization and sensor testing) and multi-fidelity numerical models spanning all lengths scales. The GAML-ANN framework will allow the concurrent optimization of processing parameters and structural features of TPU/CNT nanocomposites, enabling fabrication of high-performance, lightweight flexible sensor systems.</p> <p>Our suggested nanocomposite sensor establishes a new mainstream platform for ultrasensitive object perception, demonstrating a viable prototype for wearable proximity sensors for motion analysis and the automobile sector.</p>
390

EVALUATION OF ADDITIVE MANUFACTURINGSCALABILITY : Optimization model development for understanding the problem of Industrial 3D-printing production

Berggren, Marcus January 2019 (has links)
In industrial design, additive manufacturing technology is one of the key technologies that have changed the way of producing metal component parts on short demand. Because of competitiveness among industries and the requirement to keep up with thegrowth of thesmart factory technology, the industries are pushed to step up and take further steps towards industry 4.0. Today the AM technology is used at prototype scale, but previous literature says that for the technology to reach the full capacity, it needs to be scaled up. Previous literature shows that improvements in the supply chain are necessary in order to scale up the industrial production and achieve high-scale adoption of the technology. As there are few sourcesin the literature about AM scalability or finding critical improvements in terms of lead times, costs and material consumptions, this study will fill that gap. The main objective of this research is to study small-scale 3D printing in the AM industries with two main industrial objectives in mind: 1 –Understanding the problem of optimization of a small-scale 3D printing operation in the industry and 2 –projecting a scenario regarding the scaling up of such facilities to reach full industrial production capacity. The method used for finding improvements in the additive manufacturing supply chain was optimization. I have developed the Overall Material Flow Effectiveness model (OMFE), which is an optimization model that takes into consideration the relevantparameters of the AM material flow regarding lead times, costs and material consumption. A literature review was conducted to determine the research design and what has and not been investigated. A sensitivity analysis was performed, which provided information aboutissues of scale, size and significance of optimizing a prototyping model,andalso aboutanalyzing the optimization model development in terms of evaluating the prototyping, making it better and scaling up to high-level production. The optimal material flow of the AM industry is a scaled-up production with implemented improvements regarding transport and cost. By comparing it with the current prototype production, it is possible to identifythat all of the OMFE related factors have higher percentages. The top losses within the current AM industry are related to non-human processes. The most significant optimization loss is the loss of transport, where the time from supplier to goods reception have a significant influence. The second largestlossis cost,generated bylabour management.

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