Tesi sul tema "Additive manufacturing (FDM)"
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1
Rafaja, Hynek. "Monitorování procesu FDM tisku". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-399310.
Abstract (sommario):
The target of this work is the development of a monitoring system for 3D printing by the Fused Deposition Modeling method, which will be able to identify printing error conditions. During the solving process the needed error conditions were identified. Then, an algorithm was programmed to identify the error condition using the criterion. The resulting Monitoring Hardware was implemented in the printer and experimentally verified. A system has been developed that can identify error conditions with an accuracy of 94.7%. The main benefit of this work is the automatic identification of error conditions that stop printing if necessary. This leads to a reduction in scrap and cost savings. In the future, the software could automatically adjust the print parameters when identifying an error condition. This would prevent or completely eliminate the error condition without user intervention.
2
Ravi, Prame Manush. "Fracture Properties of Thermoplastic Composites Manufactured Using Additive Manufacturing". Youngstown State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1516191324564382.
3
Emericks, Isak. "Challanges In Constructing Large Frame FDM 3D Printers". Thesis, KTH, Skolan för industriell teknik och management (ITM), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-279503.
Abstract (sommario):
This project was initiated by Postnord who wanted to develop their own large frame FDM 3D printer, mainly for two reasons. The first reason was to be able to use the collaboration between Postnord and KTH to present how Postnord are promoting domestic production in the same time as portraying themselves as leaders in the field of additive manufacturing in Sweden. The second reason was to get a machine with the ability to print both small- and large-scale prototypes and products to be used in an industrial environment. The targeted goals and desired outcome of the PP3D (PostPaper3D - project name) was to construct a large frame FDM 3D printer, with a build area of 1 square meter and (if possible) a printing volume of 1 cubic meter, capable of printing parts for industrial applications. This would be achieved by using industrial components and state-of-the-art open source 3D printing control systems. Sensors for filament run-out detection and automatic printer bed levelling was also desired. On top of these goals KTH-IIP wanted the project work to focus on the construction of large frame FDM 3D printers, what challenges appear in scaling up the technology, to further the internal vision of developing strategic competencies in the field of additive manufacturing - as requested by the industry. The result of the project was a FDM 3D printer with a build volume of 1000x1000x950 [mm] that comes with dual independent extruders - meaning it may either print two copies of the same part simultaneously or utilize both printer heads to work on a single component. The top tested speed (printing) was 100 [mm/s] and the top tested movement speed was 250 [mm/s]. The theoretical accuracy of the machine is 50 [μm] but this has not been tested in this project. In the scope of the master thesis all prototype-symptoms were not eliminated, where the most considerable issue being the motors occasionally skipping steps (and losing their location) during rapid accelerations and changes in velocity. When this happens, it will most likely result in a failed print. The proposed solution for this is to further adjust the firmware to allow for finer, more regulated accelerations and speeds. Another possible solution is to replace the motors with stronger ones. In delivery the machine operates using state of the art components and software, from prominent Swedish and international producers. An interview of Isak Emericks alongside the printer can be seen in Appendix B, in the form of a newsletter.Det här projektet initierades av Postnord som ville utveckla en egen storskalig FDM 3D printer, huvudsakligen på grund av två anledningar. Den första för att kunna använda samarbetet med KTH för att visa hur Postnord främjar inhemsk produktion samtidigt som de själva är ledare och initiativtagare inom additiv tillverkning i Sverige. Den andra anledningen var för att få tag på en maskin som har möjligheten att skriva ut stora- och småskaliga prototyper och produkter som kan användas i en industriell miljö. De uppsatta målen och önskvärda resultatet med PP3D (PostPapper3D - projektnamn) var att konstruera en storskalig FDM 3D skrivare, men en byggarea på 1 kvadratmeter och (om möjligt) en byggvolym på 1 kubikmeter, kapabel att skriva ut delar för industriella tillämpningar. Det här skulle uppnås genom att använda industriella komponenter och toppmoderna kontrollsystem för 3D skrivare. Sensorer för att upptäcka när utskriftsmaterialet var på väg att ta slut och automatisk utjämning av byggytan var också önskvärt. Förutom dessa målsättningar så ville KTH-IIP att arbetet skulle fokusera på konstruktionen av en storskalig FDM 3D skrivare, vilka utmaningar och problem som uppstår när tekniken skalas upp, för att fortsätta den interna visionen om att utveckla strategiska kompetenser inom additiva tillverkningsmetoder - vilket industrin efterfrågade. Resultatet av projektet var en 3D skrivare med en byggvolym på 1000x1000x950 [mm] som kommer utrustad med två (individuellt styrda) utskriftshuvuden - som antingen kan skriva ut två identiska kopior av samma objekt eller som kan arbeta tillsammans för att bygga upp en komponent mer effektivt. Den högsta testade utskriftshastigheten var 100 [mm/s] och den högsta testade hastigheten för rörelse var 250 [mm/s]. Den teoretiska upplösningen hos maskinen är 50 [μm] men det här har inte kontrollerats i det här projektet. Inom omfattningen av ett examensarbete (civilingenjör) så hann inte alla prototyp-symptom elimineras, där det mest betydande problemet var att motorerna bitvis missar steg (och förlorar sin positionering) under hastiga accelerationer och förändringar i rörelseriktning. När detta händer så resulterar det oftast i misslyckade utskrifter. Den presenterade lösningen för det här är att fortsätta justera mjukvaruinställningarna tills finare och mer kontrollerade rörelsemönster uppnås. En annan tänkbar lösning är att byta ut motorerna mot starkare varianter. Vid leverans så nyttjar maskinen toppmoderna komponenter och mjukvara, från framstående svenska och internationella producenter. En intervju med Isak Emericks tillsammans med 3D skrivaren hittas i Bilaga B, i formen av ett nyhetsbrev.
4
Kota, Vasuman. "Rasters vs Contours For Thin Wall ULTEM 9085 FDM Applications". Wright State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=wright1567029612963881.
5
Sauter, Barrett. "Ultra-light weight design through additive manufacturing". Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-45160.
Abstract (sommario):
ABB Corporate Research was looking to redevelop one product to be manufactured via polymer additive manufacturing (AM), as opposed to its previously traditionally manufacturing method. The current product is cylindrical in shape and must withstand a certain amount of hydrostatic pressure. Due to the pressure and the current design, the cannister is prone to buckling failure. The cannister is currently produced from two cylindrical tube parts and two spherical end sections produced from solid blocks of the same material. For assembly, an inner assembly is inserted into one of the tube parts and then all parts are welded together. This product is also custom dimensioned for each purchase order. The purpose of investigating this redevelopment for AM is to analyse if an updated inner design unique to additive manufacturing is able to increase the performance of the product by increasing the pressure it can withstand from both a material failure standpoint and a buckling failure. The redevelopment also aims to see if the component count and process count can be decreased. Ultimately, two product solutions are suggested, one for low pressure ranges constructed in ABS and one for high pressure ranges constructed in Ultem 1010. To accomplish this, relevant literature was referred to gain insight into how to reinforce cylindrical shell structures against buckling. Design aspects unique to AM were also explored. Iterations of these two areas were designed and analysed, which led to a final design choice being decided upon. The final design is ultimately based on the theory of strengthening cylindrical structures against buckling through the use of ring stiffeners while also incorporating AM unique design aspects in the form of hollow network structures. By utilizing finite element analysis, the design was further developed until it held the pressure required. Simulation results suggest that the ABS product can withstand 3 times higher pressure than the original design while being protected against failure due to buckling. The Ultem simulation results suggest that the product can withstand 12 times higher pressure than the current design while also being protected against failure due to buckling. Part count and manufacturing processes are also found to have decreased by half. Post-processing treatments were also explored, such as the performance of sealants under pressure and the effects of sealants on material mechanical properties. Results show that one sealant in particular, an acrylic spray, is most suitable to sealing the ABS product. It withstood a pressure of 8 bar during tests. The flexural tests showed that the sealant did indeed increase certain mechanical properties, the yield strength, however did not affect the flexural modulus significantly. This work gives a clear indication that the performance of this product is feasibly increased significantly from redeveloping it specifically to AM.
6
Ferri, Martina. "Studio di nanocompositi di TPU/grafene per additive manufacturing". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/24385/.
Abstract (sommario):
La Fused Deposition Modeling (FDM) è una tecnologia di Additive Manufacturing (3D printing) adatta alla lavorazione di polimeri termoplastici e ampiamente utilizzata per la fabbricazione di oggetti con geometrie complesse. Attualmente, i principali limiti di questa tecnologia risiedono nella scarsa qualità e nelle basse proprietà meccaniche dei manufatti, se comparate a quelle di oggetti creati con tecnologie convenzionali. Questi svantaggi hanno portato ricercatori accademici e industriali a studiare nuovi materiali da processare mediante FDM che avessero performance migliori. Una delle soluzioni proposte è stata lo sviluppo di materiali compositi. Il lavoro presentato si colloca in questo contesto e si inserisce all’interno di un progetto di ricerca volto alla sintesi di nanocompositi a base di TPU rinforzato con grafene processabili tramite FDM. I nanocompositi sono stati preparati utilizzando un poliuretano termoplastico commerciale (Elastollan® C 60 A HPM (BASF)) e diverse concentrazioni di grafene commerciale (250, 1000 e 10000 ppm). La formulazione dei materiali è stata effettuata mediante solution blending. I nanocompositi ottenuti sono stati pellettizzati, estrusi per ottenere i filamenti di alimentazione per la stampante 3D ed infine stampati. Pellet, filamenti e stampati sono stati caratterizzati mediante analisi termica e comparati tra loro. I nanocompositi stampati 3D sono stati caratterizzati anche dal punto di vista meccanico (misura del coefficiente di espansione termica, analisi dinamico-meccanica e prove di trazione) ed è stata misurata la capacità termica (CP). Infine, la morfologia dei nanocompositi stampati ottenuti è stata osservata dopo frattura criogenica attraverso microscopio elettronico a scansione (SEM) e microscopia ottica digitale.
7
Ahmadifar, Mohammad. "Etude de la rhéologie des composites polymères au cours du procédé FDM (Fabrication additive)". Thesis, Paris, HESAM, 2021. http://www.theses.fr/2021HESAE072.
Abstract (sommario):
Additive manufacturing (AM) is a novel technology that enables rapid fabrication of physical models directly from 3D computer-aided design (CAD) data without any conventional tooling or programming requirement. Thermoplastic polymers are the most useful materials for the manufacturing of parts in the FFF process. In this process, extrusion of a semi-molten road through a nozzle is taken place to form each layer, the extruded road solidifies quickly due to the existence of temperature gradient between the surroundings and the extrusion temperature. Different key parameters affect the final products manufactured by this process. These parameters can be listed in three categories. Some of them are linked to the material, others are linked either to the characteristics of the process or to the specificity of the machine. They can influence the properties of the final part through their effect on various physical phenomena. The mentioned parameters affect the polymer temperature and its evolution. It is important to know the evolution of filaments temperature with time and recognize how it is affected by major process variables as mentioned. Due to the nature of the FFF process, it is important to measure the temperature profile and its evolution during the process by the means of local measurement methods. The idea of this work took place in 2018, by start reviewing literatures related to the FFF process. As mentioned, almost all studies and works either numerical or experimental approaches were based on global consideration. In the beginning, the work was concentrated on finding a method to be applied to the FFF process to proceed with the localized investigation. Afterward, the experiment was started to see the possibility of the work. As in the FFF process, there is a deposition of filaments, and each filament itself is heated by the deposition of newer filaments, there is almost a cyclic evolution of the temperature due to multi-layer d eposition and it means that each filament is re-heated consequently because of the deposition of a new filament. This is a critical issue in creating a filament bonding and diffusion of materials. To implement and measure this cyclic temperature, it is required to apply a measurement device in which to be capable of measuring the temperature of the polymer when leaving the nozzle. One can note that the mechanical properties of 3d-printed pieces are limited. In this work, we try to improve the mechanical properties by reinforcing the fibers such as glass fibers, carbon fibers, etc. At the same time by controlling the temperature evolution, we try to improve the adhesion between the layers to have the best structure. The used material as raw material was polyamide-6 (PA6). The main objective of this research is to study the rheological characteristics of materials during FDM/FFF to process optimization for mechanical characterization improvement of the fabricated parts. Therefore, the main objective is to take into account both the temperature and viscosity parameters, and to establish the Time-Temperature-Transformation diagram for process optimization. This helps to determine the processability areaAdditive manufacturing (AM) is a novel technology that enables rapid fabrication of physical models directly from 3D computer-aided design (CAD) data without any conventional tooling or programming requirement. Thermoplastic polymers are the most useful materials for the manufacturing of parts in the FFF process. In this process, extrusion of a semi-molten road through a nozzle is taken place to form each layer, the extruded road solidifies quickly due to the existence of temperature gradient between the surroundings and the extrusion temperature. Different key parameters affect the final products manufactured by this process. These parameters can be listed in three categories. Some of them are linked to the material, others are linked either to the characteristics of the process or to the specificity of the machine. They can influence the properties of the final part through their effect on various physical phenomena. The mentioned parameters affect the polymer temperature and its evolution. It is important to know the evolution of filaments temperature with time and recognize how it is affected by major process variables as mentioned. Due to the nature of the FFF process, it is important to measure the temperature profile and its evolution during the process by the means of local measurement methods. The idea of this work took place in 2018, by start reviewing literatures related to the FFF process. As mentioned, almost all studies and works either numerical or experimental approaches were based on global consideration. In the beginning, the work was concentrated on finding a method to be applied to the FFF process to proceed with the localized investigation. Afterward, the experiment was started to see the possibility of the work. As in the FFF process, there is a deposition of filaments, and each filament itself is heated by the deposition of newer filaments, there is almost a cyclic evolution of the temperature due to multi-layer d eposition and it means that each filament is re-heated consequently because of the deposition of a new filament. This is a critical issue in creating a filament bonding and diffusion of materials. To implement and measure this cyclic temperature, it is required to apply a measurement device in which to be capable of measuring the temperature of the polymer when leaving the nozzle. One can note that the mechanical properties of 3d-printed pieces are limited. In this work, we try to improve the mechanical properties by reinforcing the fibers such as glass fibers, carbon fibers, etc. At the same time by controlling the temperature evolution, we try to improve the adhesion between the layers to have the best structure. The used material as raw material was polyamide-6 (PA6). The main objective of this research is to study the rheological characteristics of materials during FDM/FFF to process optimization for mechanical characterization improvement of the fabricated parts. Therefore, the main objective is to take into account both the temperature and viscosity parameters, and to establish the Time-Temperature-Transformation diagram for process optimization. This helps to determine the processability area
8
Capriotti, Marco. "Utilizzo di scarti agroalimentari nella produzione di biocompositi per additive manufacturing". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amslaurea.unibo.it/25767/.
Abstract (sommario):
Nell’ambito delle materie plastiche, la necessità di trovare delle soluzioni al consumo di materie prime non rinnovabili per la loro produzione, attualmente dipendente dal petrolio, ha portato la ricerca allo sviluppo dei biopolimeri, tra cui il PHB, PHA, PCL, PVA e PLA, grazie alla loro biodegradabilità e compostabilità. Tra i biopolimeri presenti in commercio, il PLA è ritenuto essere il più interessante, in quanto possiede buone proprietà meccaniche e facilità di lavorazione. Attualmente l’utilizzo del PLA, rispetto alle commodities termoplastiche, presenta dei limiti legati al suo elevato costo. Nel seguente elaborato di tesi è stata posta l’attenzione sull’utilizzo di due scarti dell’industria agroalimentare quali il farinaccio di grano e la lolla del riso. Nel tentativo di valorizzare questi scarti sono stati realizzati dei biocompositi a matrice PLA al 10% e al 20% per ogni biofiller, da utilizzare nella lavorazione mediante stampa 3D. L’obbiettivo principale è quello di ridurre il contenuto di polimero nel filamento per stampa 3D, ottenendo quindi materiali eco-sostenibili possibilmente di minor costo mantenendo quanto più possibile intatte le proprietà meccaniche dei materiali stampati. I biocompositi prodotti tramite stampa 3D, sono stati sottoposti a caratterizzazione termica mediante analisi TGA e DSC volte a determinare le loro principali proprietà termiche. Inoltre mediante lo strumento DMA è stato possibile studiare il comportamento viscoelastico dei diversi formulati e determinarne il coefficiente di espansione termico lineare CLTE. Infine, mediante prove di trazione al dinamometro è stato studiato il comportamento a rottura dei materiali valutandolo su provini stampati in tre direzioni X,Y, Z rispetto all’asse di trazione e perpendicolari tra loro.
9
Bernardi, Alberto. "Controllo di un dispositivo di alimentazione filo per una stampante FDM". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
Abstract (sommario):
L’attività descritta in questo elaborato è relativa alla fase di sviluppo di un prototipo per un sistema di caricamento automatico di filamento per stampanti 3D progettate da Mark One, azienda specializzata in additive manufacturing.
In primo luogo, è stata effettuata un’analisi funzionale del problema, analizzando le specifiche tecniche richieste dall’ufficio tecnico. Si è poi proseguito con uno studio delle varie proposte, approfondendo quelle ritenute più vantaggiose e studiando i punti di forza e criticità di ognuna.
Una volta individuata la scelta più vantaggiosa, è stato realizzato il file CAD dell’elemento, scelta la componentistica e stampato il primo prototipo degli elementi.
Questo elaborato è la parte conclusiva del progetto e prevede l’implementazione delle componenti elettroniche, come del motore passo passo, sensori per la rilevazione del filamento e la creazione del codice per il microcontrollore.
10
Guglieri, Alessandro. "Design ed ottimizzazione strutturale di un APR realizzato con tecnologie additive". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/23557/.
Abstract (sommario):
L'elaborato, di tipo sperimentale, nasce da un progetto svolto durante il Laboratorio di costruzioni aeronautiche e consiste nella progettazione di un telaio di APR (Aeromobile a Pilotaggio Remoto) per riprese in volo, destinato alla produzione tramite stampa 3D.
Nella prima versione del progetto si erano resi evidenti molti difetti nel design della struttura; in vista dei possibili miglioramenti applicabili al telaio, ho deciso di cambiarne completamente la configurazione e le dimensioni, al fine di progettare un frame con la minor massa possibile per migliorare le prestazioni dell'aeromobile.
Sono stati prodotti due telai seguendo metodologie differenti. La prima consiste in una progettazione di tipo convenzionale del telaio tramite software CAD (Computer Aided Design, ossia disegno tecnico assistito dall'elaboratore). Il secondo metodo è costituito dall'utilizzo di un software che permette l'ottimizzazione topologica del componente: partendo dallo spazio di progetto, è possibile ricavare in modo semi automatico una geometria ottimizzata per resistere ai carichi assegnati.
Gli elementi del telaio sono stati pensati per essere prodotti tramite stampa 3D in materiale polimerico per valutarne successivamente le prestazioni e paragonarli in termini di massa.
11
Murrey, Jordan Alexander. "A Methodology to Evaluate the Performance of Infill Design Variations for Additive Manufacturing". Ohio University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1577967439125664.
12
PAKKANEN, JUKKA ANTERO. "Designing for Additive Manufacturing - Product and Process Driven Design for Metals and Polymers". Doctoral thesis, Politecnico di Torino, 2018. http://hdl.handle.net/11583/2714732.
Abstract (sommario):
Additive Manufacturing (AM) has broken through to common awareness and to
wider industrial utilization in the past decade. The advance of this young
technology is still rapid. In spoken language additive manufacturing is referred as
3D printing for plastic material and additive manufacturing is left as an umbrella
term for other materials i.e. metallic materials and ceramics. As the utilization of
AM becomes more widespread, the design for additive manufacturing becomes
more crucial as well as its standardization.
Additive manufacturing provides new set of rules with different design
freedom in comparison with subtractive manufacturing methods. This is thought
to empower product driven designs. However, in the AM methods there are
process driven variables that limit the designs functions to what could be
manufactured. There are often extra steps after production to finalize the design.
Topology optimization utilizes product driven design where material is only
where it is needed to be. The design is computed without taking into account any
manufacturing constrains and only the design in the final application stage is
achieved. Topology optimization algorithm is explored in detail for two
algorithms. Then these algorithms are compared in case study I to gain better
understanding of the algorithms functions. Case study I consists of 2D and 3D
algorithms where a 3D level set method algorithm was written for this purpose.
The concept of designing for additive manufacturing is examined for
polymeric materials in case study II with a help of topology optimization design
software tailored for additive manufacturing market. The parts are manufactured
with different AM methods, examined and results are explained. The results show
an interesting effect of anisotropy and the manufacture methods effect in the part
mechanical properties.
On the other hand, process driven design and its concepts important as the
manufacturing method dictates, what can and should be done economically. Metal
AM process constraints are explored in case study III through accuracy studies in
metal additive manufacturing at laser powder bed fusion (LPBF) technology.
Accuracy and surface studies are concluded to gain a better understanding of the
process and manufacturability of metal parts. The gain knowledge is explaned and
examples are shown how these are utilized to make metal parts with tailored
properties and with minimal post processing needs.
13
Hayagrivan, Vishal. "Additive manufacturing : Optimization of process parameters for fused filament fabrication". Thesis, KTH, Lättkonstruktioner, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-238184.
Abstract (sommario):
An obstacle to the wide spread use of additive manufacturing (AM) is the difficulty in estimating the effects of process parameters on the mechanical properties of the manufactured part. The complex relationship between the geometry, parameters and mechanical properties makes it impractical to derive an analytical relationship and calls for the use of a numerical model. An approach to formulate a numerical model in developed in this thesis. The AM technique focused in this thesis is fused filament fabrication (FFF). A numerical model is developed by recreating FFF build process in a simulation environment. Machine instructions generated by a slicer to build a part is used to create a numerical model. The model acts as a basis to determine the effects of process parameters on the stiffness and the strength of a part. Determining the stiffness of the part is done by calculating the response of the model to a uniformly distributed load. The strength of the part depends on it's thermal history. The developed numerical model serves as a basis to implement models describing the relation between thermal history and strength. The developed model is suited to optimize FFF parameters as it encompass effects of all FFF parameters. A genetic algorithm is used to optimize the FFF parameters for minimum weight with a minimum stiffness constraint.Ett hinder för att additiv tillverkning (AT), eller ”3D-printing”, ska få ett bredare genomslag är svårigheten att uppskatta effekterna av processparametrar på den tillverkade produktens mekaniska prestanda. Det komplexa förhållandet mellan geometri och processparametrar gör det opraktiskt och komplicerat att härleda analytiska uttryck för att förutsäga de mekaniska egenskaperna. Alternativet är att istället använda numeriska modeller. Huvudsyftet med denna avhandling har därför varit att utveckla en numerisk modell som kan användas för att förutsäga de mekaniska egenskaperna för detaljer tillverkade genom AT. AT-tekniken som avses är inriktad på Fused Filament Fabrication (FFF). En numerisk modell har utvecklats genom att återskapa FFF-byggprocessen i en simuleringsmiljö. Instruktioner (skriven i GCode) som används för att bygga en detalj genom FFF har här översatts till en numerisk FE-modell. Modellen används sen för att bestämma effekterna av processparametrar på styvheten och styrkan hos den tillverkade detaljen. I detta arbete har strukturstyvheten hos olika detaljer beräknats genom att utvärdera modellens svar för jämnt fördelade belastningsfall. Styrkan, vilket är starkt beroende på den tillverkade detaljens termiska historia, har inte utvärderats. Den utvecklade numeriska modellen kan dock fungera som underlag för implementering av modeller som beskriver relationen mellan termisk historia och styrka. Den utvecklade modellen är anpassad för optimering av FFF-parametrar då den omfattar effekterna av alla FFF-parametrar. En genetisk algoritm har använts i detta arbete för att optimera parametrarna med avseende på vikt för en given strukturstyvhet.
14
Iori, Alessandro. "Sviluppo di ambiente CAD per l'analisi di componenti aerospaziali progettati per Additive Manufacturing". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
Abstract (sommario):
L’obbiettivo di questo lavoro di tesi è la progettazione di un ambiente del software opensource FreeCAD per lo sviluppo e l’analisi di file in formato STL. Questo formato viene ampiamente utilizzato dalle macchine usate per l’additive manufacturing e descrive la geometria esterna di un componente attraverso dei triangoli. L’ambiente implementato, avendo in ingresso un file in formato STL, a seconda delle scelte dell’utente, consente di svolgere delle analisi utili a valutare parametri che impattano la produzione additiva di un componente. L’ambiente permette anche delle rotazioni dell’oggetto, così che possa essere orientato sul piatto di stampa della macchina in modo da ottenere certe proprietà che l’utente vuole ottenere, come, per esempio, orientare il componente in modo da avere pochi sottosquadri.
15
Coe, Edward Olin. "Printing on Objects: Curved Layer Fused Filament Fabrication on Scanned Surfaces with a Parallel Deposition Machine". Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/101096.
Abstract (sommario):
Consumer additive manufacturing (3D printing) has rapidly grown over the last decade. While the technology for the most common type, Fused Filament Fabrication (FFF), has systematically improved and sales have increased, fundamentally, the capabilities of the machines have remained the same. FFF printers are still limited to depositing layers onto a flat build plate. This makes it difficult to combine consumer AM with other objects. While consumer AM promises to allow us to customize our world, the reality has fallen short.
The ability to directly modify existing objects presents numerous possibilities to the consumer: personalization, adding functionality, improving functionality, repair, and novel multi-material manufacturing processes. Indeed, similar goals for industrial manufacturing drove the research and development of technologies like direct write and directed energy deposition which can deposit layers onto uneven surfaces.
Replicating these capabilities on consumer 3-axis FFF machines is difficult mainly due to issues with reliability, repeatability, and quality. This thesis proposes, demonstrates, and tests a method for scanning and printing dimensionally-accurate (unwarped) digital forms onto physical objects using a modified consumer-grade 3D printer. It then provides an analysis of the machine design considerations and critical process parameters.Master of Science
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Fiorenza, Cristina. "Preparazione e caratterizzazione di nuovi nanocompositi elastomerici mediante stampa 3D". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/20974/.
Abstract (sommario):
Il presente lavoro di tesi si è incentrato sulla preparazione e caratterizzazione di manufatti elastomerici mediante Additive Manufacturing, sfruttabili per l'abbigliamento sportivo. Sono stati studiati diversi parametri di stampa, tra cui la geometria di riempimento, angoli di deposizione, infill e velocità di stampa, al fine di ottenere prestazioni ottimizzate confrontabili con materiali convenzionali. Inoltre sono state utilizzate per lo scopo diverse matrici elastomeriche caratterizzate da differente durezza Shore A. Le proprietà termiche dei manufatti stampati sono state studiate attraverso analisi TGA e DSC. Invece, le prestazioni meccaniche sono state analizzate attraverso DMA, prove di trazione e prove di compressione/espansione. Infine, è stato sviluppato un materiale innovativo nanocomposito al fine di ampliare il campo di utilizzo della FDM. Il materiale è stato caratterizzato tramite le classiche tecniche di analisi termiche e meccaniche.
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Voigt, Sven P. "Quantifying the Hierarchical Mesostructure of Fused Deposition Modeled Materials and Measuring the Effect on the Elastic Mechanical Response". Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1511919156291091.
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Stockham, Corbin H. "Rapid Tooling Carbon Nanotube-Filled Epoxy for Injection Molding Using Additive Manufacturing and Casting Methods". Ohio University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1591803958920497.
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Vergara, Gianluca. "Produzione di un filamento a base di acido polilattico additivato con rinforzo di origine naturale per additive manufacturing". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/21683/.
Abstract (sommario):
Scopo dell'elaborato è stato la produzione di un materiale bio-composito formato da PLA ed un rinforzo di origine naturale derivante dal settore agricolo, nell'ottica di diminuire i costi dei manufatti costituiti da tale materiale, riducendo il contenuto di PLA, e rivalorizzare lo scarto di farine in applicazioni di stampa 3D. Inizialmente le farine sono state studiate mediante analisi spettroscopiche (FT-ATR), osservazioni al microscopio ottico e analisi TGA. Dopodiché sono stati prodotti filamenti per stampa 3D di materiale composito al 10% e caratterizzati termicamente (DSC, TGA, Cp) e meccanicamente (DMA). Successivamente alla stampa 3D di questi filamenti, sono stati analizzati comportamenti termici (CTE, DSC) e meccanici (prove di trazione, DMA) dei provini stampati. Si è infine valutata l'influenza del trattamento termico di ricottura sui provini stampati mediante analisi DSC e DMA.
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Palmer, Andrew. "The Design and Development of an Additive Fabrication Process and Material Selection Tool". Master's thesis, University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3635.
Abstract (sommario):
In the Manufacturing Industry there is a subset of technologies referred to as Rapid Technologies which are those technologies that create the ability to compress the time to market for new products under development . Of this subset, Additive Fabrication (AF), or more commonly known as Rapid Prototyping (RP), acquires much attention due to its unique and futuristic approach to the production of physical parts directly from 3D CAD data, CT or MRI scans, or data from laser scanning systems by utilizing various techniques to consecutively generate cross-sectional layers of a given thickness upon the previous layer to form 3D objects. While Rapid Prototyping is the most common name for the production technology it is also referred to as Additive Manufacturing, Layer Based Manufacturing, Direct Digital Manufacturing, Free-Form Fabrication, and 3-Dimensional Printing. With over 35 manufacturers of Additive Fabrication equipment in 2006 , the selection of an AF process and material for a specific application can become a significant task, especially for those with little or no technical experience with the technology and to add to this challenge, many of the various processes have multiple material options to select from . This research was carried out in order to design and construct a system that would allow a person, regardless of their level of technical knowledge, to quickly and easily filter through the large number of Additive Fabrication processes and their associated materials in order to find the most appropriate processes and material options to create physical reproductions of any part. The selection methodology used in this paper is a collection of assumptions and rules taken from the author's viewpoint of how, in real world terms, the selection process generally takes place between a consumer and a service provider. The methodology uses those assumptions in conjunction with a set of expert based rules to direct the user to a best set of qualifying processes and materials suited for their application based on as many or as few input fields the user may be able to complete.M.S.
Department of Industrial Engineering and Management Systems
Engineering and Computer Science
Industrial Engineering MS
21
Caselli, Lorenzo. "Progettazione di un sistema di caricamento automatico del filamento di una stampante 3D". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
Abstract (sommario):
L’attività descritta nel presente elaborato è relativa alla prima fase di sviluppo di un innovativo sistema di caricamento automatico del filamento per una stampante 3D, prodotto da un’azienda che opera nel settore.
In particolare, la progettazione meccanica qui illustrata è stata affrontata partendo dal progetto concettuale del nuovo dispositivo, per concludersi con il progetto costruttivo e il dimensionamento dei singoli componenti.
In primo luogo, è stata effettuata un’analisi funzionale del problema, analizzando sistematicamente le specifiche tecniche richieste ed i vincoli di progetto dettati dall’azienda. Scomposto il problema in tal modo, sono state proposte ed analizzate soluzioni concettuali alternative, valutandone comparativamente punti di forza e criticità. Una volta individuata la soluzione ritenuta più vantaggiosa, si sono dimensionati opportunamente i componenti commerciali (e scelti a catalogo) e progettati quelli da realizzare ad hoc (con processo di produzione in additive manufacturing, secondo le richieste dell’azienda).
L’elaborato è parte integrante di un progetto che prevede le successive fasi di prototipazione e programmazione del controller del sistema di caricamento automatico del filamento.
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KHAN, FAHAD AHMAD. "Developing Robot assisted Plastic 3D Printing Platform". Thesis, KTH, Skolan för industriell teknik och management (ITM), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-295472.
Abstract (sommario):
This project was initiated by Dr. Sasan Dadbaksh upon listening to the requirements I presented for my master thesis. My requirements were to do a master thesis project in the field of additive manufacturing specifically fused deposition modeling that should not only involve the research work but should also present an opportunity to develop hardware and should involve experimental testing. Then Sasan came up with the idea of developing a system capable to perform 3D printing with the extruder fixed in one position and the motion required for 3D printing will be provided by the robotic arm. The title of developing green build strategies for robot assisted plastic 3D printing came into being. The main concept behind the title of developing robot assisted plastic 3D printing platform is to develop such a system that can offer additive manufacturing services, specifically of fused deposition modeling 3D printing, as an inbound process during the manufacturing of any part through subtractive processes with the help of a robotic arm along with the repair of any kind of parts with the assistance of fused deposition modeling 3D printing. The main objectives of the master thesis include building a stationary filament extrusion module to interact with a robot hand and establishing a strategy for a robot hand to move the part to appropriate locations to complete building a part on a preform without support structures. The targets that were achieved with the completion of this thesis project includes the development of the complete hardware that consists of a mechanical structure with the option of mounting the components required to run the extrusion setup, learning the basic working of the software that are able to simulate the 3D printing process with the robotic arm (Robot Studio and Robo DK), creation of the simulation of the whole process, achieving communication between the robotic arm and the microcontroller of the extruder and finally the printing of a simple part for the demonstration. The components needed to be installed on the structure includes the motor, extruder, hot end, nozzle, filament. The structure also accumulated the required electronics that includes power supply, microcontroller, and an LCD to monitor the extrusion parameters. The developed machine runs on the state-of-the-art components that belong to the few of the best manufacturers of the technology.
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Prusic, André. "Perimeter". Thesis, KTH, Arkitektur, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-146717.
Abstract (sommario):
The project explores the possibilities of using additive manufacturing (3d-printing) to build architecture. Through a combination of theoretical research and practical experiments a building system has been developed which has the capabilities to create houses with great geometric flexibilities to a affordable price today. The construction system Perimeter is demonstrated in a pavilion situated at Norra Djurgården in Stockholm.Projektet undersöker möjligheterna att använda additiv tillverkning (3d-printning) för att bygga arkitekturen. Genom en kombination av teoretisk forskning och praktiska experiment har ett byggsystem utvecklats som har kapacitet att skapa hus med stora geometriska flexibilitet till ett överkomligt pris i dag. Konstruktionssystemet Perimeter demonstreras i en paviljong belägen på Norra Djurgården i Stockholm.
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Gullapalli, Ram A. "A Study of Mixed Manufacturing Methods in Sand Casting Using 3D Sand Printing and FDM Pattern-making Based on Cost and Time". Youngstown State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1485335857475363.
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Franzén, Johan. "FrankZlicer : Direct slicing using arcs". Thesis, Mittuniversitetet, Avdelningen för data- och systemvetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-36021.
Abstract (sommario):
3D printing a CAD modelnormally requires conversion into a polygon mesh, usually an STL-file, in orderto be able to load the model in the slicer. This conversion destroys roundsurfaces and replaces them with flat surfaces. Slicing a polygon mesh resultsin one or more polygons, consisting of a number of straight lines. This canaffect both dimensional accuracy and surface smoothness. Modern 3D-printerscan, in addition to straight lines, handle arcs. However, today’s commonslicers can not generate arcs as the input does not contain any curvedfeatures. This project aims at finding an alternative solution. By directslicing of CAD models the slices can contain arcs, and the slicer can producearc commands for the 3D-printer. During this project a prototype slicer isconstructed as a proof of concept. The prototype handles STEP-files as inputand creates both linear and circular movement for the 3D-printer. The resultsshow that both the intermediate files (STEP/STL) and the resulting G-code filescan get smaller, yet preserving the original shape, by using this method. Theproposed solution has a positive effect on the 3D-printing workflow as well, asthe intermediate files can be imported back into the CAD system. The projectconcludes that there is possibly a bright future for direct slicing, but thereare more problems to solve before it can become reality.
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De, Martino Luciano. "Caratterizzazione di un materiale composito innovativo trasformato mediante tecnologia additiva". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
Abstract (sommario):
L’obiettivo di questa tesi di laurea sarà quella di analizzare e studiare i limiti di una tecnologia
innovativa di stampa FDM di paste a freddo, costituite da una miscela di argilla e prodotti
di scarto (PA12) derivanti dal processo di tecnologia additiva Multi Jet Fusion, realizzata
da HP.
Particolare attenzione è stata rivolta allo studio delle tracce di estrusione, all’analisi dell’ accuratezza
dimensionale dei provini estrusi e all’incidenza della quantità di polvere di PA12
sulle caratteristiche meccaniche dei provini nelle prove ad impatto, al fine di valutare criticità
e punti di forza di questo nuovo processo.
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Chaloupka, Matyáš. "Konstrukce 3D tiskárny pro tisk materiálu s příměsí karbonových vláken". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-318141.
Abstract (sommario):
The presented thesis deals with FDM 3D printing method with emphasis on printing carbon fiber reinforced plastic (CFRP). The aim of this thesis is to engineer the FDM 3D printer designed for printing CFRP and to execute the experiment targeted on comparison of CFRP material properties against commonly used 3D printing plastics such as PLA, ABS, PET etc. The device designed in this work has printing area of 200 x 200 mm with maximum height of the object of 200 mm. The printing bed is heated and the whole device is enclosed. There are two kinds of experiments carried out within the thesis. The first one is focused on tensile strength and Young's modulus of selected materials, while the second experiment compares Charpy's impact strength of specimen with different infill percentage on two selected materials, PET and PET filled with chopped carbon fiber.
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Pooladvand, Koohyar. "Multifunctional Testing Artifacts for Evaluation of 3D Printed Components by Fused Deposition Modeling". Digital WPI, 2019. https://digitalcommons.wpi.edu/etd-dissertations/568.
Abstract (sommario):
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.
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Branco, Rodolfo Ramos Castelo. "Elaboração de protocolo de ensaios mecânicos para avaliação da performance do material PLA através da manufatura aditiva por meio do processo FDM". Universidade Estadual da Paraíba, 2016. http://tede.bc.uepb.edu.br/jspui/handle/tede/3071.
Abstract (sommario):
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Technological innovation has been a constant in several areas in the contemporary world, emphasizing in the areas of engineering and health. In this scenario, there is the Additive Manufacturing (MA), which consists of a manufacturing process using the addition of material in successive flat layers, in which it is possible to generate 3D physical parts obtained directly from CAD (Computer Aided Design). The MA is divided into several processes, in this study it will be highlighted by Fusion and Deposition Modeling (FDM) of the solids class, which uses solid polymer coils, especially Poly lactic acid (PLA). This technology of manufacturing process has been gaining more and more prominence in the technological scenario, with which it is possible to affirm that the Additive Manufacturing is on a scale of growth, being considered by many scholars as the new industrial revolution, which obviously opens space for New research in the area, thus necessitating the consolidation of processes, machinery and materials. In this context of recognition of the participation that the Additive Manufacturing process has been achieving, this study aimed to elaborate mechanical testing protocols for the evaluation of PLA material performance through the MA from the FDM process. The applied methodology was based on studying the parameters of construction of the pieces in FDM (structure, raster, deposition rate, temperature, loops, orientation of the raster angle, position orientation of the pieces, among others), to perform the mechanical tests of the Type and analyze the results obtained through strain-strain graphs (maximum tensions, rupture and modulus of elasticity). The result obtained evidenced little difference between the deposition rates (20%, 50% and 100%) regarding the construction time. Regarding the mechanical properties, the pieces with 100% fill characteristics in their internal structure presented better tensions. It was also observed the influence of the position of construction of the specimens in the printing tray, changing its mechanical characteristics.
A inovação tecnológica tem sido uma constante em diversas áreas no mundo contemporâneo, destacando-se nas áreas de engenharia e saúde. Neste cenário, encontra-se a Manufatura Aditiva (MA), que consiste em um processo de fabricação utilizando a adição de material em camadas planas sucessivas, no qual é possível gerar peças físicas em 3D, obtidas diretamente de arquivos de modelagem CAD (Computer Aided Design). A MA divide-se em vários processos, neste estudo será destacado por Modelagem de fusão e deposição (FDM) da classe dos sólidos, o qual utiliza bobinas de polímeros sólidos, especialmente o Poli ácido láctico (PLA). Esta tecnologia de processo de fabricação vem ganhando cada vez mais destaque no cenário tecnológico, com isso é possível afirmar que a Manufatura aditiva se encontra em uma escala de crescimento, sendo considerada por muitos estudiosos como a nova revolução industrial, o que obviamente abre espaço para novas pesquisas na área, havendo assim a necessidade da consolidação dos processos, máquinas e materiais. Neste contexto de reconhecimento da participação que o processo de Manufatura Aditiva vem alcançando, este estudo visou elaborar protocolos de ensaios mecânicos para avaliação de performance do material PLA através da MA a partir do processo FDM. A metodologia aplicada baseou-se em estudar os parâmetros de construção das peças em FDM (estrutura, raster, taxa de deposição, temperatura, loops, orientação do ângulo raster, orientação da posição das peças, dentre outros), em realizar os ensaios mecânicos do tipo tração e analisar os resultados obtidos através dos gráficos de tensão-deformação (tensões máxima, ruptura e modulo de elasticidade). O resultado obtido evidenciou pouca diferença entre as taxas de deposição (20%, 50% e 100%) no tocante ao tempo de construção. Em relação as propriedades mecânicas, as peças de características 100% de preenchimento em sua estrutura interna apresentaram melhores tensões. Observou-se também, a influência da posição de construção dos corpos de prova na bandeja de impressão, alterando suas características mecânicas.
30
Stellmar, Justin. "Predicting the Deformation of 3D Printed ABS Plastic Using Machine Learning Regressions". Youngstown State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1587462911261523.
31
ANDERSSON, AXEL. "Automation of Fused Filament Fabrication : Realizing Small Batch Rapid Production". Thesis, KTH, Skolan för industriell teknik och management (ITM), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-299447.
Abstract (sommario):
In this bachelor thesis, I examine how automation of fused filament fabrication (FFF) can be implemented, and what the limitations are for different kinds of automation solutions for FFF. Fused filament fabrication is a 3D-printing technology where a material is extruded through a nozzle, layer by layer, to create a print. The thesis also provides a calculation for the commercial feasibility of small batch rapid production with the implementation of an automation solution for FFF. The approach was a qualitative study containing five interviews, combined with empirical knowledge and data from the additive manufacturing company Svensson 3D. This was complemented with an analysis of which criteria to use when evaluating FFF automation solutions, and a framework for looking at FFF from an operator perspective. To calculate commercial feasibility of automation solutions for FFF, Internal Rate of Return and Payback Time were used. This resulted in six criteria to evaluate solutions for automation of FFF, three evaluations of problems within three solutions for automation of FFF, and a finding showing that small batch rapid production is commercially feasible with automated FFF. Lastly, the thesis contains a discussion regarding what the future is for FFF, and the limitations of the framework presented for evaluating automated FFF systems. Possible promising solutions for automated FFF are presented, together with ideas for how design for additive manufacturing can help shape the future of automated FFF.I det här kandidatarbetet undersöker jag hur automatisering inom fused filament fabrication (FFF) kan implementeras, och vad begränsningarna är för olika sorters automatiseringslösningar för FFF. Det läggs även fram en uträkning för den kommersiella gångbarheten för small batch rapid production med implementeringen av ett automatiskt FFF-system. Tillvägagångsättet bestod av en kvalitativ studie baserad på fem intervjuer, kombinerad med empirisk kunskap och data från additiva tillverkningsföretaget Svensson 3D. Det här kompletterades med en analys av vilka parametrar som bör användas för att utvärdera lösningar för FFF-automatisering, och ett ramverk där automatiseringslösningarna betraktas ur ett operatörs-perspektiv. För att räkna ut den kommersiella gångbarheten för automatiseringslösningar av FFF användes internränta och återbetalningstid. Det här resulterade i sex parametrar för att utvärdera automatiseringslösningar för FFF, tre utvärderingar av vilka problem som finns i tre existerande automatiseringslösningar, och slutsatsen att small batch rapid production är kommersiellt gångbart för automatiserad FFF. Slutligen innehåller arbetet en diskussion gällande framtiden för FFF och begränsningarna hos det ramverk som presenterades för att utvärdera automatiserade FFF system. Möjliga lovande lösningar för automatiserad FFF presenteras och hur design för additiv tillverkning kan hjälpa till att forma framtiden för automatiserad FFF.
32
Engkvist, Gustav. "Investigation of microstructure and mechanical properties of 3D printed Nylon". Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-66304.
Abstract (sommario):
This thesis presents a multiscale investigation and characterization of additive manufactured Polyamide material using fused deposition modelling technique. Manufacturing was performed using Markforgeds – Mark one 3D printer. A multiscale investigation dedicated to minimizing the effect of shape distortion during 3D printing are presented, focusing on both molecular alignment in microstructure and implementing internal structures in mesostructure. Characterization on samples investigating microstructure was performed with coefficient of linear thermal expansion measurement and 3-point bending experiment. Different samples with varying infill patterns are tested and results indicates an isotropic behaviour through the manufactured samples and implies no molecular alignment due to printing pattern. In meso-structure, an implemented internal pattern is investigated. All samples are measured with 3D scanning equipment to localize and measure the magnitude of shape distortion. Attempts to find relationships in shape distortion and porosity between the samples resulted in no observed trends. Compressive experiments where performed on samples in axial- and transverse directions resulting in anisotropic behaviour. The largest compressive stiffness is recorded in axial direction reaching 0,33 GPa. The study is done in collaboration with Swerea SICOMP and Luleå University of Technology.
33
M'Bengue, Marie-Stella. "Conception et évaluation d'une endoprothèse vasculaire par impression 3D pour le traitement des anévrismes complexes de l'aorte abdominale". Electronic Thesis or Diss., Université de Lille (2022-....), 2022. http://www.theses.fr/2022ULILS057.
Abstract (sommario):
La réparation endovasculaire (EVAR) d'un anévrisme de l'aorte abdominale (AAA) consiste en la mise en place d'une endoprothèse (EDP) par chirurgie mini-invasive au sein de l'anévrisme. Cet acte permet de prévenir la rupture des tissus endommagés impliqués dans un AAA, défini comme la dilatation localisée du diamètre de l'aorte. Lorsque l'amont de l'anévrisme englobe les artères périphériques rénales et/ou viscérales, l'AAA est qualifié de complexe. Dans ce cas, l'EDP déployée est dite « fenêtrée », en d'autres termes, perforée à l'emplacement des jonctions vers les artères périphériques. La prise en charge dans le cadre d'un AAA complexe devient alors plus limitante car l'EDP fenêtrée sera conçue sur mesure afin de correspondre à l'anatomie de l'anévrisme et à la position des artères périphériques du patient. Cela implique un délai de fabrication de plusieurs semaines, limite la prise en charge aux anévrismes stables et exclut les situations d'urgence. Dans ce contexte, l'impression 3D présente un intérêt considérable pour la fabrication d'EDP sur mesure et dans des délais très courts. Ainsi, l'objectif de ce travail de thèse est de concevoir un prototype d'endoprothèse par impression 3D d'un polyuréthane thermoplastique (TPU) de grade médical (élastomère thermoplastique). Le présent travail permettra de valider le procédé de conception et la fonctionnalité de notre 3D-EDP pour son application finale en tant que dispositif médical implantable.Dans un premier temps, l'impact du procédé de fabrication sur les propriétés chimiques, physiques et physico-chimiques du TPU a été étudié à chaque étape, des granulés à la stérilisation par rayons gamma d'une prothèse fabriquée par dépôt de filament fondu (FDM). L'évaluation préliminaire in vitro de la cytotoxicité et de l'hémocompatibilité du TPU a été réalisée après l'étape d'impression 3D et de stérilisation. Un vieillissement préliminaire du TPU en conditions oxydantes extrêmes a été réalisé afin de prédire l'évolution de ses propriétés sur le long terme. Par la suite, une stratégie de conception d'un prototype implantable par voie endovasculaire a été développée. Les propriétés de ce prototype stérilisé ont été caractérisées par différentes techniques (CES, ATG, DSC, FTIR, MEB, goniométrie, traction uniaxiale, …). Ses propriétés biologiques ont été évaluées in vitro par des tests de cytocompatibilité, hémocompatibilité et contact avec les macrophages pendant 24 heures (inflammation aigüe). L'évolution de ses propriétés physico-chimiques et mécaniques a été suivie par des études de vieillissement in vitro.La caractérisation des propriétés chimiques, physiques et physico-chimiques du TPU a montré que l'impression 3D FDM et la méthode de stérilisation par rayons gamma constituent une voie de fabrication viable d'un prototype comprimable dans un cathéter d'introduction endovasculaire. L'évaluation biologique in vitro a montré la cytotocompatibilité du prototype par la méthode de l'extrait. De plus, le prototype s'est révélé faiblement hémolytique et les plaquettes adhérant à sa surface n'étaient pas activées. La faible sécrétion de cytokines (IL-6 et TNF-a) au contact des macrophages inactivés a montré que le prototype d'EDP ne présente pas de caractère pro-inflammatoire. Enfin, les études de vieillissement ont montré un impact sur les propriétés mécaniques et de surface de notre prototype d'EDP sans toutefois compromettre sa fonctionnalité. Par la suite, la stratégie de conception pourrait évoluer vers une fonctionnalisation de l'EDP afin de prévenir les infections et les thromboses responsables respectivement de 2% et 6% des complications post-opératoiresEndovascular repair (EVAR) of an abdominal aortic aneurysm (AAA) involves the placement into the aneurysm of a stent graft (SG) by minimally invasive surgery. This procedure prevents rupture of the damaged tissue involved in an AAA, defined as a localized diameter dilation of the aorta. When the upstream portion of the aneurysm includes the peripheral renal and/or visceral arteries, the AAA is qualified as complex. In this case, the deployed SG is said “fenestrated”, in other words, perforated at the site of junctions to the peripheral arteries. Management of a complex AAA becomes more limiting as the fenestrated SG will be custom designed to match the anatomy of the aneurysm and the position of the peripheral arteries of the patient. This implies a manufacturing delay of several weeks, limits the management to stable aneurysms and excludes emergency situations. In this context, 3D printing (3DP) is of considerable interest for the fabrication of custom-made SGs in a very short time frame. Thus, the objective of this thesis work is to design a SG prototype by 3D printing of a medical grade thermoplastic polyurethane (TPU) (thermoplastic elastomer). The present work will validate the manufacturing process and the functionality of our 3DP-SG for its final application as an implantable medical device.First, the impact of the manufacturing process on the chemical, physical and physicochemical properties of TPU was studied at each step, from the pellets to the gamma-ray sterilization of a graft manufactured by fused filament deposition (FDM). In vitro preliminary evaluation of the cytotoxicity and hemocompatibility of TPU was carried out after the 3D printing and sterilization step. Aging of TPU under extreme oxidizing conditions was performed to predict the evolution of its properties in the long term. Subsequently, a design strategy for an endovascular implantable prototype was developed. The properties of said prototype were characterized by different techniques (SEC, TGA, DSC, FTIR, SEM, goniometry, uniaxial traction, ...). Its biological properties were evaluated in vitro by tests of cytocompatibility, hemocompatibility and contact with macrophages for 24 hours (acute inflammation). Moreover, the evolution of its physicochemical and mechanical properties was evaluated by in vitro aging studies.The characterization of the chemical, physical and physicochemical properties of TPU enabled the validation of a FDM printing manufacturing route and gamma ray sterilization of a crimpable SG prototype. The in vitro biological evaluation showed the non-cytotoxicity of the SG prototype by the extraction method. Moreover, the prototype was found to be weakly hemolytic and the platelets adhered on its surface were not activated. The low secretion of cytokines (IL-6 and TNF-α) upon contact with inactivated macrophages showed that the SG prototype does not exhibit a pro-inflammatory characteristic. Finally, aging studies showed an impact on the mechanical and surface properties of our SG prototype without compromising its functionality. Subsequently, the design strategy could evolve towards a functionalization of the SG prototype in order to prevent infections and thrombosis responsible for 2% and 6% of postoperative complications respectively
34
Lami, Isacco. "Ottimizzazione di strutture reticolari in additive manufacturing". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
Abstract (sommario):
Nel presente documento vengono illustrate le potenzialità delle micro strutture reticolari e le relative tecniche di additive manufacturing necessarie per realizzarle.
A partire da questo vengono presentate le problematiche relative all'analisi FEM di tali strutture, confrontando i risultati ottenuti dalle simulazioni con dati sperimentali ricavati da articoli scientifici. Tali difficoltà sono legate alla complessità di queste strutture e all'elevato numero di elementi. Infine, viene proposto un approccio di tipo "building block" per risolvere le difficoltà computazionali sopra citate e vengono valutati pro e contro di questa soluzione.
35
Abdelki, Andreas. "Fused deposition modeling of API-loaded mesoporous magnesium carbonate". Thesis, Uppsala universitet, Nanoteknologi och funktionella material, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-417897.
Abstract (sommario):
In this thesis, the incorporation of drug loaded mesoporous magnesium carbonate as an excipient for the additive manufacturing of oral tablets by fused deposition modeling was investigated. Cinnarizine, a BCS class II drug, was loaded into the pores of the mesoporous material via a soaking method, corresponding to a drug loading of 8.68 wt%. DSC measurements on the loaded material suggested that the drug was partially crystallized after incorporation, meanwhile the XRD diffractogram implied that the drug was in a state lacking long range order. The drug loaded material was combined with two pharmaceutical polymers, Aquasolve LG and Klucel ELF, and extruded into filaments with a single screw extruder. Filaments of Klucel ELF and drug loaded Upsalite (30:70 wt% ratio) were successfully implemented for the printing oral tablets, in contrast to the Aquasolve LG based filaments which were difficult to print due to thickness variations and non-uniform material distributions. The drug content obtained by TGA suggested drug loadings of 7.71 wt% and 2.23 wt% in the drug loaded Upsalite and tablets respectively. Dissolution studies using an USP II apparatus showed a slower API-release from the tablets in comparison to the crystalline drug, most probably due to slow diffusion of drug species through the polymeric matrix. For future studies, pharmaceutical polymers with higher aqueous solubility should be investigated in order to thoroughly examine the potential of utilizing the immediate release property of Upsalite.
36
Chen, Shuai. "Investigation of FEM numerical simulation for the process of metal additive manufacturing in macro scale". Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI048/document.
Abstract (sommario):
La fabrication additive (FA) est devenue une nouvelle alternative pour la fabrication des pièces dans l'industrie. Cependant, il existe encore des limites pour ce procédé, en particulier la forme finale défavorable et les propriétés macroscopiques indésirables des pièces métalliques construites dans les systèmes de FA. La distorsion ou la fissure due à la contrainte résiduelle de ces pièces pose généralement de graves problèmes pour certains types de technologie de la FA métallique. Dans un système de FA, la qualité finale d'une pièce métallique dépend de nombreux paramètres de procédé, qui sont normalement optimisés par une série d'expériences sur des machines de FA. La simulation macroscopique dédiée au procédé de FA est une alternative potentielle pour les pièces métalliques fabriquées par la fabrication additive. Dans cette thèse, nous étudions d'abord le pré-processing de la simulation de FA par la méthode des éléments finis (FEM). Le procédé de fabrication additive est un phénomène multi-physique des champs couplés (champs thermique, mécanique et métallurgique). La simulation macroscopique est réalisée à deux niveaux différents. Au niveau de la couche, la reconstruction du modèle 3D est effectuée à partir du fichier de chemin de balayage de la machine de FA, basée sur la manipulation inverse de l'algorithme d'offsetting-clipping. Au niveau de la pièce, le modèle 3D de CAO est reconstruit dans un maillage des voxels, ce qui est pratique pour une pièce avec une géométrie complexe. Avec les températures de préchauffage différentes et les paramètres du procédé différents, la contrainte résiduelle d'une pièce est analysée. Ces simulations impliquent la technique potentielle pour réduire la contrainte résiduelle par l'optimisation des paramètres du procédé, au lieu de moyens traditionnels par augmenter la température de préchauffage. Basées sur la plateforme de simulation de FEM ci-dessus, deux simulations au niveau de ligne sont également étudiées dans cette thèse, visant à la relation entre le procédé de FA et la qualité finale de la pièce. Ces exemples démontrent la possibilité d'utiliser des simulations macroscopiques pour améliorer le contrôle de la qualité pendant le procédé de FA. Dans la première tâche, l'ensemble de données des paramètres de chauffage et la contrainte résiduelle sont générés par la simulation de FA. La corrélation entre eux est étudiée en utilisant des algorithmes de régression, tel que le réseau neuronal artificiel. Dans la deuxième tâche, un contrôleur de PID pour la boucle de rétroaction puissance-température est intégré dans la simulation de procédé de FA et l'auto-réglage de PID est numériquement étudié au lieu d'utiliser la machine de FA. Les deux tâches montrent le rôle important de la simulation de procédé macroscopique de FA, qui peut remplacer ou combiner les nombreuses expériences essai-erreur dans la fabrication additive métalliqueAdditive manufacturing (AM) has become a new option for the fabrication of metallic parts in industry. However, there are still some limitations for this application, especially the unfavourable final shape and undesired macroscopic properties of metallic parts built in AM systems. The distortion or crack due to the residual stress of these parts leads usually to severe problems for some kinds of metal AM technology. In an AM system, the final quality of a metallic part depends on many process parameters, which are normally optimized by a series of experiments on AM machines. In order to reduce the considerable time consumption and financial expense of AM experiments, the numerical simulation dedicated to AM process is a prospective alternative for metallic part fabricated by additive manufacturing. Because of the multi-scale character in AM process and the complex geometrical structures of parts, most of the academic researches in AM simulation concentrated on the microscopic melting pool. Consequently, the macroscopic simulation for the AM process of a metallic part becomes a current focus in this domain. In this thesis, we first study the pre-processing of AM simulation on Finite Element Method (FEM). The process of additive manufacturing is a multi-physics problem of coupled fields (thermal, mechanical, and metallurgical fields). The macroscopic simulation is conducted in two different levels with some special pre-processing work. For the layer level, the reconstruction of 3D model is conducted from the scan path file of AM machine, based on the inverse manipulation of offsetting-clipping algorithm. For the part level, the 3D model from CAD is reconstructed into a voxel-based mesh, which is convenient for a part with complex geometry. The residual stress of a part is analysed under different preheat temperatures and different process parameters. These simulations imply the potential technique of reducing residual stress by the optimisation of process parameters, instead of the traditional way by increasing preheat temperature. Based on the FEM simulation platform above, two simulations at line level are also studied in this thesis, aiming at the relation between the AM process and part's final quality. These examples demonstrate the feasibility of using macroscopic simulations to improve the quality control during the AM process. In the first task, dataset of heating parameters and residual stress are generated by AM simulation. The correlation between them is studied by using some regression algorithm, such as artificial neural network. In the second task, a PID controller for power-temperature feedback loop is integrated into AM process simulation and the PID auto-tuning is numerically investigated instead of using AM machine. Both of the two tasks show the important role of AM macroscopic process simulation, which may replace or combine with the numerous trial and error of experiments in metal additive manufacturing
37
Pastuglia, Matteo. "Applicazione delle tecniche additive ad una lama per pattinaggio di figura". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
Abstract (sommario):
In questa tesi è stato studiato il comportamento meccanico di una lama di pattino da ghiaccio cui sono state aggiunte strutture in lattice all'interno di alcune zone del componente. Inizialmente sono esposte le principali tecniche di additive manufacturing, le strutture lattice, la fabbricazione additiva e l'analisi agli elementi finiti. Successivamente sono illustrate le varie tappe che hanno portato alla realizzazione del pattino, studiati i risultati dell'analisi FEM, ed è stata introdotta la geometria reticolare all'interno del pattino.
Lo studio si è posto l'obiettivo di progettare una lama per pattino da ghiaccio e di inserire, dopo un'attenta analisi delle varie sollecitazioni, un reticolo 3D in modo da diminuirne il peso senza comprometterne le performance da un punto di vista meccanico.
38
Severino, Giosuè. "Design, manufacturing and test of a SynRM motor prototype". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022.
Abstract (sommario):
In this thesis, we will discuss the methodologies for the design of the mechanical components of the variable reluctance motor, developed for the ACMEC project.
All the fundamental design points are discussed, getting to know the design methodologies and explaining the reasons for various choices made for the production of the component.
39
Gatti, Ilaria. "Confronto fra un componente realizzato in additive manufacturing e il suo equivalente realizzato con tecniche tradizionali". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/17129/.
Abstract (sommario):
Nel seguente elaborato ci si propone di confrontare una biella con struttura lattice, realizzata con tecniche di additive manufacturing, con un suo equivalente realizzato con tecniche di produzione tradizionale. I componenti saranno confrontati in termini di massa, proprietà meccaniche ricavate tramite analisi FEM e tempo computazionale necessario a svolgere quest’ultime.
40
Settanni, Antonio. "Comparazione strutturale di componenti realizzati a terra e nello spazio mediante tecniche additive". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2016.
Abstract (sommario):
Questo lavoro di tesi mira ad indagare, a livello preliminare, quali siano i vantaggi e gli svantaggi a livello strutturale legati alla possibilità di realizzare componenti per mezzi spaziali con tecnologie di Rapid Prototyping direttamente nello spazio: questa possibilità verrà confrontata con il caso in cui gli stessi componenti siano realizzati a terra e poi inviati nello spazio con un lanciatore. Nonostante si siano riscontrati dei limiti derivanti dalla carenza di dati tecnici sulle caratteristiche meccaniche dei materiali, è stata sviluppata una metodologia che ha fornito l’opportunità, seppur con grandi approssimazioni, di valutare il problema.
Il punto di partenza dell’attività è stato quello di visionare figure ed immagini di mezzi spaziali e di scegliere alcuni componenti che possano essere oggetto di manutenzione o sostituzione in volo. Sei componenti sono stati poi modellati al CAD, ed è stata condotta un’analisi ad elementi finiti (FEM) mediante il software MSC Patran/Nastran, con lo scopo di simulare la risposta strutturale nelle diverse condizioni di carico prese in considerazione.
Seppur a livello qualitativo e del tutto preliminare, sono stati svolti dei confronti in termini di massa e tensioni per valutare in quali casi sembra sia conveniente realizzare un componente a terra con tecnologie tradizionali, e in quali sembra sia vantaggioso utilizzare nuove tecnologie di prototipazione rapida stampando direttamente il componente nello spazio.
41
Di, Santi Filippo. "Ottimizzazione topologica di paratie di pressurizzazione di velivoli commerciali". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
Abstract (sommario):
In questa tesi sono trattate la produzione e l'ottimizzazione di paratie di pressurizzazione di velivoli commerciali.
Sono stati confrontati i dati inerenti alla piegatura della paratia provenienti dall'equazione analitica e dall'analisi FEM, mentre, per quanto riguarda l'ottimizzazione, è stato effettuato uno studio sui rinforzi alla ricerca della soluzione migliore in termini di peso e di distribuzione delle tensioni.
42
Bianchi, Alfredo. "Implementazione di moduli per la modellazione CAD di strutture aerospaziali basate su elementi lattice". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
Abstract (sommario):
In questa tesi vengono affrontati principalmente due temi riguardanti le strutture in materiale lattice: il primo consiste nel poter applicare la teoria dell’omogeneizzazione asintotica descritta da A. Vigliotti e D. Pasini a tali strutture, nell’ipotesi di materiale equivalente isotropo e corpo denso. In altre parole, date le caratteristiche geometriche e fisiche della cella elementare componente il lattice, si vuole verificare se è possibile trovare un modulo di Young equivalente E_eq e un coefficiente di Poisson equivalente v_eq tali da poter essere utilizzati nell’analisi FEM della stessa struttura vista come corpo denso (ossia privo di vuoti tra le celle elementari) in materiale isotropo. Dalla valutazione dell’errore commesso rispetto ai risultati dell’analisi FEM sulla struttura lattice e rispetto all’analisi FEM effettuata su MATLAB con l’ipotesi di materiale equivalente ortotropo e corpo denso (definito da tre parametri indipendenti α, β, γ ) si vedrà che questo approccio non è possibile, pertanto per effettuare l’analisi FEM su un corpo denso equivalente alla struttura lattice non è possibile utilizzare programmi open source come CalculX, in dotazione a FreeCAD, in cui non si possa definire un materiale equivalente anisotropo, ossia definito da più di due parametri indipendenti. Al contrario software come MATLAB risultano affidabili poiché consentono di definire la matrice di elasticità equivalente completa del materiale.
Il secondo tema riguarda la realizzazione di un algoritmo per FreeCAD in grado di realizzare in modo automatico strutture lattice basate sulla cella elementare cubica. Tale algoritmo può essere richiamato mediante apposita icona presente nell’ambiente LWSM, realizzato dall’università di Bologna e da me arricchito con le funzioni qui descritte.
43
Pietrangelo, Alessio. "Realizzazione e caratterizzazione di una placca cranica mediante produzione additiva e materiale polimerico". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022.
Abstract (sommario):
L’Additive Manufacturing rappresenta uno dei metodi produttivi che negli ultimi anni sta attirando sempre più attenzione, espandendosi in maniera esponenziale sempre in più settori, tra cui il biomedicale, in particolare nella realizzazione di dispositivi chirurgici impiantabili. Al giorno d’oggi sono ancora molti gli studi volti a determinare i processi produttivi e i materiali ottimali per la realizzazione di questi dispositivi, che devono soddisfare determinati requisiti di performance e biocompatibilità. Questo elaborato di tesi si inserisce in un progetto più ampio, portato avanti dal Policlinico Sant’Orsola in collaborazione con l’Università di Bologna, volto a valutare le tecnologie e i materiali ideali nella realizzazione di una protesi impiantabile. Ci si è focalizzati sulla tecnologia Arburg Plastic Freeforming, un innovativo processo di AM che utilizza granulati standard come materia prima, e sul Policarbonato Uretano, un polimero di grado medico con ottime performance. Nella prima fase di questo progetto è stata effettuata una caratterizzazione termica del materiale attraverso prove reologiche, analisi DSC e TGA. Si è quindi passati alla messa a punto dei parametri di stampa per il materiale considerato, che è stato quindi caratterizzato meccanicamente attraverso delle prove di flessione a tre punti. Per studiare il comportamento del PCU in una specifica applicazione di protesi chirurgica è stata realizzata una placca cranica mediante APF che è stata sottoposta a dei test sperimentali di compressione e di impatto, riproducendo le condizioni a cui potrebbe essere soggetta una protesi di questo tipo in condizioni reali di utilizzo. Sono state infine realizzate delle analisi FEM di flessione a tre punti per validare il modello di materiale utilizzato, e delle simulazioni di compressione e di impatto sul modello di placca cranica, validando e verificando l’accuratezza del modello numerico attraverso un confronto con i corrispettivi test sperimentali.
44
Vellone, Davide. "Ottimizzazione strutturale di una bulkhead di fusoliera di velivoli da trasporto commerciale". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
Abstract (sommario):
The present state-of-the-art of the rear pressure bulkhead foresees the use of two types of materials: aluminium alloy Al2024 (exploited in the applications where tensile or fatigue loads are predominant like in the fuselage paneling) and composite materials (carbon fiber reinforced polymer).
For the metallic case, the problem of the deep drawing of an aluminium alloy sheet into a hemispheric dome consists in the phenomenon of wrinkles formation (wrinkling); this is linked to the thickness of the plate and its dimensions.
In this thesis we provide a carrying out solution by additive manufacturing.
On the base of what developed by Airbus, which created AM spoiler prototypes taking inspiration from the structure of lily pad, this thesis work aims to develop a bulkhead and its stiffeners design optimization.
The use of additive manufacturing in the bulkhead production shows two big advantages compared to traditional working: the chance to create complex geometries and the absence of internal residual stress and wrinkling phenomenon.
The analysis of the studied structures allows to verify
advantage of the rounded bulkhead configuration instead of the plane one (almost one lower order of magnitude for displacements), structural optimization due to stiffeners, consistency with lily pad shape.
45
Iacob, Alexandru Sorin. "Studio comparativo tra configurazioni alari convenzionali e con struttura lattice". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2019.
Abstract (sommario):
Lo studio effettuato ha lo scopo di confrontare un’ala per impiego aerospaziale o automotive con configurazione convenzionale e una con riempimento con struttura di tipo lattice regolare cubica non conforme, al fine di determinare se un’ala ottenuta mediante stampa con tecniche di additive manufacturing è in grado di competere con un’ala ottenuta attraverso metodi convenzionali a livello di massa a parità di sollecitazione massima.
Il confronto è stato effettuato sia a pari peso calcolando le massime tensioni, sia ad equivalenti sollecitazioni esterne, andando a verificare i pesi ottenuti.
A tale scopo è stata impiegata una analisi 1-way FSI che coinvolge sia simulazioni CFD che FEM.
È stato anche messo in pratica un approccio di analisi semplificativo che consiste nello studiare la struttura lattice come se fosse un materiale continuo, cercando di capire se il cosiddetto metodo di omogeneizzazione applicato al caso di studio in questione, permette di ottenere risultati soddisfacenti riducendo di gran lunga i tempi di calcolo.
46
Grunden, Eric Hans. "Examination of Rapid Prototype Tooling". The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1460495153.
47
Conti, Alfredo. "Tecniche della manifattura additiva - applicazioni in ambito aeronautico e aerospaziale". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amslaurea.unibo.it/13306/.
Abstract (sommario):
Il potenziale delle nuove tecnologie digitali applicate al settore industriale ha consentito di ridurre enormemente la durata dei cicli produttivi grazie alla rapida gestione di quantità di dati sempre più considerevoli attraverso l’introduzione delle Macchine a Controllo Numerico (Computer Numerical Control – CNC).
Nel corso delle ultime tre decadi, l’industria manifatturiera ha subito notevoli e sostanziali cambiamenti grazie ad una sempre più forte connessione con il mondo dell’informatica.
La più grande rivoluzione in tale ambito è stata segnata dall’avvento della Manifattura Additiva (Additive Manufacturing - AM), conosciuta sotto diversi nomi, tra i quali Prototipazione Rapida (Rapid Prototyping), Manifattura Rapida (Rapid Manufacturing) o Libera Fabbricazione di Forme (Free Form Fabrication).
Materia di ricerca e sviluppo sin dalla fine degli anni ’80, la Manifattura Additiva consente la creazione di elementi fisici tridimensionali partendo da modelli CAD attraverso la sovrapposizione successiva di materiale strato per strato (layer by layer), offrendo i benefici di una elevata flessibilità geometrica degli elaborati, altrimenti irraggiungibile attraverso le tradizionali tecniche di Manifattura Sottrattiva operanti per asportazione di materiale. In seguito ad intensive ricerche, progressi significativi sono stati fatti nello sviluppo e nella commercializzazione di nuovi ed innovativi processi AM.
48
Myers, Eric J. "Finite Element Modeling (FEM) of Porous Additively Manufactured Ferromagnetic Shape Memory Alloy Using Scanning Electron Micrograph (SEM) Based Geometries". Youngstown State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ysu149399154152881.
49
Lazzarini, Lorenzo. "Ottimizzazione mediante codici di calcolo open source di componenti per il settore aerospaziale". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2016.
Abstract (sommario):
Lo scopo della presente tesi è sviluppare un ambiente per l'ottimizzazione strutturale di componenti per applicazione aerospaziale utilizzando codici open-source. In particolare, il codice Salome viene utilizzato per il disegno automatico delle strutture, il programma Code Aster permette di effettuare l'analisi agli elementi finiti del componente, mentre Octave viene utilizzato per svolgere l'ottimizzazione basata su un algoritmo euristico e per integrare fra di loro i differenti codici.
Le tecniche di ottimizzazione dei componenti stanno rivestendo sempre più importanza visto che le moderne tecniche di Additive Manufacturing permettono di realizzare strutture molto complesse che un tempo non era conveniente (o possibile) realizzare con asportazione di materiale. Nella prima parte della tesi si descrivono gli strumenti software utilizzati e la loro integrazione al fine di parametrizzare la generazione di geometrie ed effettuare in modo automatico analisi strutturali.
Successivamente si descrivono tre casi di studio in cui la metodologia è stata sperimentata: un primo caso di validazione in cui si è applicato il metodo alla definizione della geometria di minimo peso per una trave a sbalzo con carico concentrato, un secondo test di ottimizzazione di un longherone per aeromobile, un terzo caso applicativo legato alla ottimizzazione di un serbatoio per fluidi in pressione da utilizzare su un satellite.
50
Panaro, Giuseppe. "Studio numerico e sperimentale su una placca cranica impiantabile realizzata mediante manifattura additiva". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
Abstract (sommario):
Nell'ambito del progetto "PEEK/PEKK/CRF PEEK for Patient Specific Implants", questo lavoro di tesi nasce dalla collaborazione fra il laboratorio di bioingegneria eDIMES del Policlinico Sant'Orsola Malpighi e l'Università di Bologna. L’obiettivo dei ricercatori è valutare i metodi produttivi e i materiali ideali per la realizzazione della singola PSI.
In particolare, questa tesi si inserisce nelle fasi introduttive di generazione di un modello CAD e dell'analisi del comportamento della placca soggetta a condizioni operative reali.
In questo studio è stata efficacemente prodotta una geometria computazionale solida della protesi, in grado di fornire un modello robusto e abbastanza accurato per la realizzazione di campioni stampati con tecnologia Arburg Freeforming in PEKK e PCU per i test futuri.
Tale modello è stato anche inserito efficacemente in una simulazione FEM parametrica avvalorata da test sperimentali (di compressione e ad impatto) in cui, una volta ottenute maggiori informazioni sulle proprietà dei materiali, sarà possibile studiare la protesi in qualsiasi condizione operativa.