Rozprawy doktorskie na temat „Hybrid additive manufacturing”
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Bandiera, Nicholas Graham. "Hybrid inkjet and direct-write multi-material additive manufacturing". Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/111774.
Pełny tekst źródłaCataloged from PDF version of thesis.
Includes bibliographical references (pages 77-79).
Recently there has been a trend towards combining multiple forms of additive manufacturing together for increased functionality, freedom and efficiency. In this work, two forms of multiple-material additive manufacturing technologies - inkjet and direct-ink writing - are combined in a hybrid system. Several advantages are realized due to the increased material library and geometric freedom as a result of new printing modalities. Initially, models of each process are reviewed and the processes are evaluated for compatibility. Then, the precision machine design of a passively-indexed, carousel-style, syringe tool holder is completed. An error budget employing Homogeneous Transformation Matrices was maintained to estimate the tooltip errors. In order to register these two non-contact printing processes, a unique approach to their registration to a common global origin was necessary. A single non-contact optical CCD micrometer is used to register the three spatial coordinates of the syringe tooltip. Measurements are performed to characterize the repeatability of the nozzle registration scheme and the constructed gantry and carousel system, which well exceeds the requirements and the predictions from the conservative error budget. This novel system can print with a wide array of inks, including those that solidify via polymerization or crosslinking, two part chemistries, solvent evaporation or sintering, as well as liquids, gels and pastes. These materials can have a wide range of mechanical properties and functionalities, for example electrical conductivity or force sensitive resistivity. Models for the extrudate flow rate are used alongside experimental determination of the extrudate cross-section to ensure accurate process congruence. Finally, printed results demonstrate the various printing techniques, highlight the expanded material library, and display novel assemblies not possible with conventional additive processes. One such example is a fully printed pressure sensor array.
by Nicholas Graham Bandiera.
S.M.
Bandiera, Nicholas Graham. "Hybrid inkjet and direct-write multi-material additive manufacturing". Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111774.
Pełny tekst źródłaCataloged from PDF version of thesis.
Includes bibliographical references (pages 77-79).
Recently there has been a trend towards combining multiple forms of additive manufacturing together for increased functionality, freedom and efficiency. In this work, two forms of multiple-material additive manufacturing technologies - inkjet and direct-ink writing - are combined in a hybrid system. Several advantages are realized due to the increased material library and geometric freedom as a result of new printing modalities. Initially, models of each process are reviewed and the processes are evaluated for compatibility. Then, the precision machine design of a passively-indexed, carousel-style, syringe tool holder is completed. An error budget employing Homogeneous Transformation Matrices was maintained to estimate the tooltip errors. In order to register these two non-contact printing processes, a unique approach to their registration to a common global origin was necessary. A single non-contact optical CCD micrometer is used to register the three spatial coordinates of the syringe tooltip. Measurements are performed to characterize the repeatability of the nozzle registration scheme and the constructed gantry and carousel system, which well exceeds the requirements and the predictions from the conservative error budget. This novel system can print with a wide array of inks, including those that solidify via polymerization or crosslinking, two part chemistries, solvent evaporation or sintering, as well as liquids, gels and pastes. These materials can have a wide range of mechanical properties and functionalities, for example electrical conductivity or force sensitive resistivity. Models for the extrudate flow rate are used alongside experimental determination of the extrudate cross-section to ensure accurate process congruence. Finally, printed results demonstrate the various printing techniques, highlight the expanded material library, and display novel assemblies not possible with conventional additive processes. One such example is a fully printed pressure sensor array.
by Nicholas Graham Bandiera.
S.M.
Joshi, Anay. "Geometric Complexity based Process Selection and Redesign for Hybrid Additive Manufacturing". University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin151091601846356.
Pełny tekst źródłaStrong, Danielle B. "Analysis of AM Hub Locations for Hybrid Manufacturing in the United States". Youngstown State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1495202496133841.
Pełny tekst źródłaGamaralalage, Sanjeewa S. J. "Additive Based Hybrid Manufacturing Workstations to Reuse and Repair PrismaticPlastic Work Parts". Ohio University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1480512115077584.
Pełny tekst źródłaMomsen, Timothy Benjamin. "Hybrid additive manufacturing platform for the production of composite wind turbine blade moulds". Thesis, Nelson Mandela Metropolitan University, 2017. http://hdl.handle.net/10948/19091.
Pełny tekst źródłaNorthrup, Nathan Joseph. "Durability of Hybrid Large Area Additive Tooling for Vacuum Infusion of Composites". BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/7759.
Pełny tekst źródłaPerini, Matteo. "Additive manufacturing for repairing: from damage identification and modeling to DLD processing". Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/268434.
Pełny tekst źródłaPerini, Matteo. "Additive manufacturing for repairing: from damage identification and modeling to DLD processing". Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/268434.
Pełny tekst źródłaJuhasz, Michael J. "In and Ex-Situ Process Development in Laser-Based Additive Manufacturing". Youngstown State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ysu15870552278358.
Pełny tekst źródłaFalck, Rielson [Verfasser]. "A new additive manufacturing technique for layered metal-composite hybrid structures / Rielson Miler Moreira Falck". Hamburg : Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 2020. http://d-nb.info/1224270835/34.
Pełny tekst źródłaMaturi, Mirko <1993>. "Advanced Functional Organic-Inorganic Hybrid (Nano)Materials: from Theranostics to Organic Electronics and Additive Manufacturing". Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amsdottorato.unibo.it/9739/1/Maturi_Mirko_tesi.pdf.
Pełny tekst źródłaGingerich, Mark Bryant. "Joining Carbon Fiber and Aluminum with Ultrasonic Additive Manufacturing". The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1461161262.
Pełny tekst źródłaChamberlain, Britany L. "Additively-Manufactured Hybrid Rocket Consumable Structure for CubeSat Propulsion". DigitalCommons@USU, 2018. https://digitalcommons.usu.edu/etd/7285.
Pełny tekst źródłaZhu, Zicheng. "A process planning approach for hybrid manufacture of prismatic polymer components". Thesis, University of Bath, 2013. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648939.
Pełny tekst źródłaAlmerbati, Nehal. "Hybrid heritage : an investigation into the viability of 3D-printed Mashrabiya window screens for Bahraini dwellings". Thesis, De Montfort University, 2016. http://hdl.handle.net/2086/12482.
Pełny tekst źródłaHabib, MD Ahasan. "Designing Bio-Ink for Extrusion Based Bio-Printing Process". Diss., North Dakota State University, 2019. https://hdl.handle.net/10365/32045.
Pełny tekst źródłaChen, Tianran. "Generation of Recyclable Liquid Crystalline Polymer Reinforced Composites for Use in Conventional and Additive Manufacturing Processes". Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/103439.
Pełny tekst źródłaDoctor of Philosophy
The large demand for high performance and light weight composite materials in various industries (e.g., automotive, aerospace, and construction) has resulted in accumulation of composite wastes in the environment. Reuse and recycling of fiber reinforced composites are beneficial from the environmental and economical point of view. However, mechanical recycling deteriorates the quality of traditional fiber reinforced composite (e.g., glass fiber and carbon fiber). There is a need to develop novel composites with greater recyclability and high-performance. Thermotropic liquid crystalline polymers (TLCP) are attractive high performance materials because of their excellent mechanical properties and light weight. The goal of this work is to generate recyclable thermotropic liquid crystalline polymer (TLCP) reinforced composites for use in injection molding and 3D printing. In the first part of this work, a novel recyclable TLCP reinforced composite was generated using the grinding and injection molding. Recycled TLCP composites were as strong as the virgin TLCP composites, and the mechanical properties of TLCP composites were found to be competitive with the glass fiber reinforced counterparts. In the second part, a hybrid TLCP and glass fiber reinforced composite with great recyclability and excellent processability was developed. The processing conditions of injection molding were optimized by rheological tests to mitigate fiber breakage and improve the processability. Finally, a high performance and light weight TLCP reinforced composite filament was generated using the dual extrusion process which allowed the processing of two polymers with different processing temperatures. This composite filament could be directly 3D printed using a benchtop 3D printer. The mechanical properties of 3D printed TLCP composites could rival 3D printed traditional fiber composites but with the potential to have a wider range of processing shapes.
Liu, Fengyuan. "Design, fabrication and evaluation of a hybrid biomanufacturing system for tissue engineering". Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/design-fabrication-and-evaluation-of-a-hybrid-biomanufacturing-system-for-tissue-engineering(13717125-61ac-4f95-a83b-62a706a5ea15).html.
Pełny tekst źródłaLan, Di. "Development of 3-D Printed Hybrid Packaging for GaAs-MEMS Oscillators based on Piezoelectrically-Transduced ZnO-on-SOI Micromechanical Resonators". Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7690.
Pełny tekst źródłaMathias, Spencer D. "Investigation of Thermoplastic Polymers and Their Blends for Use in Hybrid Rocket Combustion". DigitalCommons@USU, 2019. https://digitalcommons.usu.edu/etd/7416.
Pełny tekst źródłaNeff, Clayton. "Analysis of Printed Electronic Adhesion, Electrical, Mechanical, and Thermal Performance for Resilient Hybrid Electronics". Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7551.
Pełny tekst źródłaArmstrong, Isaac W. "Development and Testing of Additively Manufactured Aerospike Nozzles for Small Satellite Propulsion". DigitalCommons@USU, 2019. https://digitalcommons.usu.edu/etd/7428.
Pełny tekst źródłaBradford-Vialva, Robyn L. "Development of a Metal-Metal Powder Formulations Approach for Direct Metal Laser Melting of High-Strength Aluminum Alloys". University of Dayton / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1620259752540201.
Pełny tekst źródłaJacques, Marjorie. "Développement d'une méthode de conception de moules et noyaux hybrides en fonderie". Thesis, Reims, 2019. http://www.theses.fr/2019REIMS021.
Pełny tekst źródłaThe aim of this works is to define a design methodology of hybrids casting molds. This methodology is based on technical and economical limits of conventional process and 3D sand printing. Firstly, these limits were evaluated by mechanical and dimensional characterization of 3D sand printing molds. Mechanical characterization was realised by three points bending test and compression testing with different parameters. 3D printer dimensional capability was determined by samples measure printed in different directions. Secondly, the design method of conventional molds was established from smelters know-how which are ANR MONARCHIES project partner from different case study. Inherent design rules of sand 3D printer were defined from the ITHEMM laboratory research works and completed with parts studies. 3D printing molds design process was created by design rules and validated with studies cases. Manufacturing cost of printing molds was defined by analytic and parametric method. The hybrids molds design methodology relies on all previous works and on complexity index. Optimal manufacturing process for different molds parts was selected according to the complexity index value, mould assembly restraint and manufacturability cost. Finally, this methodology was tested on representative sample group of casting parts, allowed to evaluate the robustness
Laplanche, Etienne. "Filtres à forts facteurs de qualité accordables continument". Thesis, Limoges, 2019. http://www.theses.fr/2019LIMO0064/document.
Pełny tekst źródłaNew needs in the field of satellite telecommunications have led manufacturers in the sector to focus on optimizing resources by creating reconfigurable systems able to adapt their operating frequencyplan during the mission. This thesis focuses on multiplexers and how to make them agile through their architecture and the filters that compose them.This manuscript starts by realizing the state of the art oftunable filtering devices through analysis of contributions made by research teams around the world. Based on this state of art,solutions to the problematic are proposed using a hybrid coupler multiplexing topology. Then studies are presented on various tunable cavities or coupling elements concepts. Some of these concepts have been selected and assembled to form tunable filtering and multiplexing functions. The last part thus presents two tunable multiplexers, allowing narrowband or broadband reconfiguration. An experimental realization has also been conducted on the narrowband version
Ushakov, Ilia. "Établissement des structures et propriétés mécaniques de l’alliage d’Inconel 625 dans les procédés d’élaboration additive à grande vitesse : arc fil, laser fil, laser poudre et hybride". Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0147.
Pełny tekst źródłaThis work focuses on the establishment of microstructures and the characterization of the mechanical properties of Inconel 625 alloy produced as part of the PAM-PROD project aimed at producing large parts using high deposition rate additive manufacturing. Three deposition techniques are being studied: Arc/Wire, Laser/Wire and Laser/Powder, as well as a combination of Laser/Wire and Laser/Powder to produce a hybrid wall. Macrostructures and microstructures are characterized for each process. The Arc/Wire and Laser/Powder processes used lead to a mixed columnar - equiaxed macrostructure. The Laser/Wire process leads to predominantly columnar structures. Mechanisms for the formation of columnar/equiaxed structures and transitions are proposed. These mechanisms are then taken up and completed to interpret the formation of the transition zone in the case of a hybrid Laser Wire/Powder wall. The response to solution heat treatment and ageing is then presented by detailing and comparing the kinetics and mechanisms specific to each process. The tensile mechanical properties along 3 directions are then characterized and related to the structures. For all the processes, a high degree of reproducibility is obtained and none of the processes has a brittle character. The best properties were obtained with the Laser/Powder process, and the hybrid junction test showed that the transition zone was not a weak point in the structure
Keerthi, Sandeep. "Low Velocity Impact and RF Response of 3D Printed Heterogeneous Structures". Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1514392165695378.
Pełny tekst źródłaSilva, Eva Carolina Ferreira da. "Thermal performance of additive manufacturing materials for hybrid moulds". Master's thesis, 2018. http://hdl.handle.net/1822/65006.
Pełny tekst źródłaHybrid moulds are an increasingly considered alternative for prototype series or short production runs, where the moulding inserts are produced by Additive Manufacturing (AM) in alternative materials, namely polymers. However, one of the main issues associated with the use of these materials is their thermal behaviour due, mainly, to the low thermal conductivity values. This study aims to evaluate the thermal performance of moulding inserts produced via Rapid Prototyping (RP) and conventional manufacturing techniques as well as the resulting moulded part quality, supported by Computer-Aided Engineering (CAE) simulations results, through Moldex3D software. The first part of this research was centered on the analysis and characterization of eight different materials from three different technologies (Material Jetting, Fused Deposition Modelling (FDM) and Direct Metal Laser Sintering (DMLS)) in order to define the suitable materials to apply in hybrid moulds. Therefore this first investigation permitted to narrow the Additive Manufacturing (AM) materials to just two polymeric materials that were further studied. Three insert materials and technologies were evaluated: Objet500 Connex3 using Digital ABS Thin Walls, Fortus 900mc using PPSF and machining using P20 steel. Dimensional accuracy, temperatures along the cycles, longevity of the moulding inserts, part quality and shrinkage behaviour of Polyoxymethylene (POM) mouldings were recorded. In the end, it was found that PPSF moulding inserts had worse surface finishing than Digital ABS Thin Walls, which originated parts with worse quality. However, Digital ABS Thin Walls was suitable for this application and using spray air as a complement of cooling decreased significantly the cycle time and had not any consequences in the shrinkage of the moulded parts.
Os moldes híbridos são uma alternativa cada vez mais procurada para a produção de protótipos ou séries curtas, onde os insertos moldantes são produzidos por manufatura aditiva, em materiais alternativos, nomeadamente polímeros. No entanto, uma das principais questões associadas ao uso destes materiais é a sua performance térmica, principalmente ao nível da condutividade. Este estudo pretende não só avaliar e comparar a performance térmica de insertos moldantes produzidos por prototipagem rápida e por técnicas de maquinação convencionais, como também a qualidade da peça resultante. Estes resultados foram validados por simulações CAE, através do software Moldex3D. Assim, numa primeira fase, a pesquisa focou-se em analisar e caracterizar oito materiais distintos, de três tecnologias distintas (Material Jetting, FDM e DMLS) para aplicação em moldes híbridos. Estes resultados permitiram selecionar dois materiais poliméricos de manufatura aditiva, que continuaram a ser estudados. Posteriormente, foram avaliadas três tecnologias e materiais: Objet500 Connex3 com Digital ABS Thin Walls, Fortus 900mc com PPSF e maquinação convencional com aço P20, ao nível da precisão dimensional, temperaturas ao longo dos ciclos e longevidade dos insertos moldantes e a qualidade e contração das peças produzidas em POM. No final, observou-se que os insertos moldantes em PPSF tiveram pior acabamento superficial, o que originou peças com pior qualidade do que usando Digital ABS Thin Walls. Contudo, este último mostrou-se uma boa solução para aplicação em moldes híbridos e usar ar comprimido como complemento de arrefecimento diminui significativamente o tempo de ciclo, não trazendo consequências na contração das moldações.
This work was funded by National Funds through FCT - Portuguese Foundation for Science and Technology, Reference UID/CTM/50025/2013 and FEDER funds through the COMPETE 2020 Programme under the project number POCI-01-0145-FEDER-007688 and by the European Structural and Investment Funds in the FEDER component, through the Operational Competitiveness and Internationalization Programme (COMPETE 2020) [Project nº 002814; Funding Reference: POCI-01-0247-FEDER-002814 and Project nº 002797; Funding Reference: POCI-01-0247-FEDER-002797].
Jayant, Hemang Kumar. "Design and Development of Hybrid Metal and Polymer Additive Manufacturing System". Thesis, 2022. https://etd.iisc.ac.in/handle/2005/5854.
Pełny tekst źródłaMontevecchi, Filippo. "Analysis and optimization of hybrid WAAM-milling process". Doctoral thesis, 2018. http://hdl.handle.net/2158/1126901.
Pełny tekst źródła(5929505), Eduardo Barocio. "FUSION BONDING OF FIBER REINFORCED SEMI-CRYSTALLINE POLYMERS IN EXTRUSION DEPOSITION ADDITIVE MANUFACTURING". Thesis, 2020.
Znajdź pełny tekst źródłaExtrusion deposition additive manufacturing (EDAM) has enabled upscaling the dimensions of the objects that can be additively manufactured from the desktop scale to the size of a full vehicle. The EDAM process consists of depositing beads of molten material in a layer-by-layer manner, thereby giving rise to temperature gradients during part manufacturing. To investigate the phenomena involved in EDAM, the Composites Additive Manufacturing Research Instrument (CAMRI) was developed as part of this project. CAMRI provided unparalleled flexibility for conducting controlled experiments with carbon fiber reinforced semi-crystalline polymers and served as a validation platform for the work presented in this dissertation.
Since the EDAM process is highly non-isothermal, modeling heat transfer in EDAM is of paramount importance for predicting interlayer bonding and evolution of internal stresses during part manufacturing. Hence, local heat transfer mechanisms were characterized and implemented in a framework for EDAM process simulations. These include local convection conditions, heat losses in material compaction as well as heat of crystallization or melting. Numerical predictions of the temperature evolution during the printing process of a part were in great agreement with experimental measurements by only calibrating the radiation ambient temperature.
In the absence of fibers reinforcing the interface between adjacent layers, the bond developed through the polymer is the primary mechanisms governing the interlayer fracture properties in printed parts. Hence, a fusion bonding model was extended to predict the evolution of interlayer fracture properties in EDAM with semi-crystalline polymer composites. The fusion bonding model was characterized and implemented in the framework for EDAM process simulation. Experimental verification of numerical predictions obtained with the fusion bonding model for interlayer fracture properties is provided. Finally, this fusion bonding model bridges the gap between processing conditions and interlayer fracture properties which is extremely valuable for predicting regions with frail interlayer bond within a part.(9012281), Pasita Pibulchinda. "The Effects of Fiber Orientation State of Extrusion Deposition Additive Manufactured Fiber-Filled Thermoplastic Polymers". Thesis, 2020.
Znajdź pełny tekst źródłaExtrusion Deposition Additive Manufacturing (EDAM) is a process in which fiber-filled thermoplastic polymers are mixed and melted in an extruder and deposited onto a build plate in a layer-by-layer basis. Anisotropy caused by flow-induced orientation of discontinuous fibers along with the non-isothermal cooling process gives rise to internal stresses in printed parts which results in part deformation. The deformation and residual stresses can be abated by modifying the fiber orientation in the extrudate to best suit the print geometry. To that end, the focus of this research is on understanding the effect of fiber orientation state and fiber properties on effective properties of the printed bead and the final deformation of a part. The properties of three different orientation tensors of glass fiber-filled polyamide and carbon fiber-filled polyamide were experimentally and virtually characterized via micromechanics. A thermo-mechanical simulation framework developed in ABAQUS© was used to understand the effects of the varying fiber orientation tensor and fiber properties on the final deformation of printed parts. In particular, a medium-size geometry that is prone to high deformation was simulated and compared among the three orientation tensors and two material systems. This serves to be a good preliminary study to understand microscopic properties induced deformations in EDAM.
Oliveira, Hugo Miguel Lopes de. "Development, programming and start-up of an interchangeable 3D-printing module". Master's thesis, 2017. http://hdl.handle.net/10400.8/3254.
Pełny tekst źródła(11189886), Diane Collard. "Enhancing Solid Propellants with Additively Manufactured Reactive Components and Modified Aluminum Particles". Thesis, 2021.
Znajdź pełny tekst źródłaA variety of methods have been developed to enhance solid propellant burning rates, including adjusting oxidizer particle size, modifying metal additives, tailoring the propellant core geometry, and adding catalysts or wires. Fully consumable reactive wires embedded in propellant have been used to increase the burning rate by increasing the surface area; however, the manufacture of propellant grains and the observation of geometric effects with reactive components has been restricted by traditional manufacturing and viewing methods. In this work, a printable reactive filament was developed that is tailorable to a number of use cases spanning reactive fibers to photosensitive igniters. The filament employs aluminum fuel within a printable polyvinylidene fluoride matrix that can be tailored to a desired burning rate through stoichiometry or aluminum fuel configuration such as particle size and modified aluminum composites. The material is printable with fused filament fabrication, enabling access to more complex geometries such as spirals and branches that are inaccessible to traditionally cast reactive materials. However, additively manufacturing the reactive fluoropolymer and propellant together comes attendant with many challenges given the significantly different physical properties, particularly regarding adhesion. To circumvent the challenges posed by multiple printing techniques required for such dissimilar materials, the reactive fluoropolymer was included within a solid propellant carrier matrix as small fibers. The fibers were varied in aspect ratio (AR) and orientation, with aspect ratios greater than one exhibiting a self-alignment behavior in concordance with the prescribed extrusion direction. The effective burning rate of the propellant was improved nearly twofold with 10 wt.% reactive fibers with an AR of 7 and vertical orientation.
The reactive wires and fibers in propellant proved difficult to image in realistic sample designs, given that traditional visible imaging techniques restrict the location and dimensions of the reactive wire due to the necessity of an intrusive window next to the wire, a single-view dynamic X-ray imaging technique was employed to analyze the evolution of the internal burning profile of propellant cast with embedded additively manufacture reactive components. To image complex branching geometries and propellant with multiple reactive components stacked within the same line of sight, the dynamic X-ray imaging technique was expanded to two views. Topographic reconstructions of propellants with multiple reactive fibers showed the evolution of the burning surface enhanced by the geometric effects caused by the faster burning fibers. These dual-view reconstructions provide a method for accurate quantitative analysis of volumetric burning rates that can improve the accessibility and viability of novel propellant grain designs.
(5931092), Ehsan Maleki Pour. "Innovative Tessellation Algorithm for Generating More Uniform Temperature Distribution in the Powder-bed Fusion Process". Thesis, 2019.
Znajdź pełny tekst źródłaMaleki, Pour Ehsan. "Innovative Tessellation Algorithm for Generating More Uniform Temperature Distribution in the Powder-bed Fusion Process". Thesis, 2018. http://hdl.handle.net/1805/17386.
Pełny tekst źródłaPowder Bed Fusion Additive Manufacturing enables the fabrication of metal parts with complex geometry and elaborates internal features, the simplification of the assembly process, and the reduction of development time. However, the lack of consistent quality hinders its tremendous potential for widespread application in industry. This limits its ability as a viable manufacturing process particularly in the aerospace and medical industries where high quality and repeatability are critical. A variety of defects, which may be initiated during the powder-bed fusion additive manufacturing process, compromise the repeatability, precision, and resulting mechanical properties of the final part. The literature review shows that a non-uniform temperature distribution throughout fabricated layers is a significant source of the majority of thermal defects. Therefore, the work introduces an online thermography methodology to study temperature distribution, thermal evolution, and thermal specifications of the fabricated layers in powder-bed fusion process or any other thermal inherent AM process. This methodology utilizes infrared technique and segmentation image processing to extract the required data about temperature distribution and HAZs of the layer under fabrication. We conducted some primary experiments in the FDM process to leverage the thermography technique and achieve a certain insight to be able to propose a technique to generate a more uniform temperature distribution. These experiments lead to proposing an innovative chessboard scanning strategy called tessellation algorithm, which can generate more uniform temperature distribution and diminish the layer warpage consequently especially throughout the layers with either geometry that is more complex or poses relatively longer dimensions. In the next step, this work develops a new technique in ABAQUS to verify the proposed scanning strategy. This technique simulates temperature distribution throughout a layer printed by chessboard printing patterns in powder-bed fusion process in a fraction of the time taken by current methods in the literature. This technique compares the temperature distribution throughout a designed layer printed by three presented chessboard-scanning patterns, namely, rastering pattern, helical pattern, and tessellation pattern. The results confirm that the tessellation pattern generates more uniform temperature distribution compared with the other two patterns. Further research is in progress to leverage the thermography methodology to verify the simulation technique. It is also pursuing a hybrid closed-loop online monitoring and control methodology, which bases on the introduced tessellation algorithm and online thermography in this work and Artificial Neural Networking (ANN) to generate the most possible uniform temperature distribution within a safe temperature range layer-by-layer.