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Artigos de revistas sobre o assunto "3D extruded geometries"
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Teixeira, João, Cecília Ogliari Schaefer, Lino Maia, Bárbara Rangel, Rui Neto e Jorge Lino Alves. "Influence of Supplementary Cementitious Materials on Fresh Properties of 3D Printable Materials". Sustainability 14, n.º 7 (28 de março de 2022): 3970. http://dx.doi.org/10.3390/su14073970.
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The development of printers and materials for 3D Printing Construction during the last two decades has allowed the construction of increasingly complex projects. Some of them have broken construction speed records due to the simplification of the construction process, particularly in non-standard geometries. However, for performance and security reasons the materials used had considerable amounts of Portland cement (PC), a constituent that increases the cost and environmental impact of 3D Printable Materials (3DPM). Supplementary Cement Materials (SCM), such as fly ash, silica fume and metakaolin, have been considered a good solution to partially replace PC. This work aims to study the inclusion of limestone filler, fly ash and metakaolin as SCM in 3DPM. Firstly, a brief literature review was made to understand how these SCM can improve the materials’ 3DP capacity, and which methods are used to evaluate them. Based on the literature review, a laboratory methodology is proposed to assess 3DP properties, where tests such as slump and flow table are suggested. The influence of each SCM is evaluated by performing all tests on mortars with different dosages of each SCM. Finally, a mechanical extruder is used to extrude the developed mortars, which allowed us to compare the results of slump and flow table tests with the quality of extruded samples.
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Sciannandrone, Daniele, Simone Santandrea e Richard Sanchez. "Optimized tracking strategies for step MOC calculations in extruded 3D axial geometries". Annals of Nuclear Energy 87 (janeiro de 2016): 49–60. http://dx.doi.org/10.1016/j.anucene.2015.05.014.
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Buj-Corral, Irene, José Antonio Padilla, Joaquim Minguella-Canela, Lourdes Rodero, Lluís Marco e Elena Xuriguera. "Design of Pastes for Direct Ink Writing of Zirconia Parts with Medical Applications". Key Engineering Materials 958 (5 de outubro de 2023): 157–63. http://dx.doi.org/10.4028/p-izk9dd.
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Direct ink writing (DIW) is an extrusion additive manufacturing (AM) technique in which inks are extruded through a nozzle and then deposited layer-by-layer. This technology allows 3D printing many different materials such as ceramics, metals, food, etc. In this work, the performance of zirconia pastes is addressed. The pastes are composed of yttria stabilized zirconia (YSZ) powder and a polymeric binder. Ceramic content is a mix of two components: A and B. Both the total content of ceramic and the content of component A in the paste are varied, according to a 32 design of experiments. The paste was characterized regarding Densification (%) and Elastic modulus G’ (Pa). A new parameter w3/G’ is defined to evaluate the viscosity of the inks. In the tests, the ceramic percentage is limited by the pressing force of the plunger that will be used to extrude the pastes. On the other hand, the binder concentration is also limited, because it requires to be in a gel form in order to be properly extruded. The results showed that Densification depends mainly on ceramic content, while the w3/G’ parameter is related to percentage of component A. In this work, the properties of the pastes prior to 3D printing are assessed. However, in the future, the pastes will be used to extrude complex parts with medical applications. AM extrusion processes constitute a possible way to overcome the difficulties to obtain complex geometries with conventional methods such as machining, in which zirconia parts can break due to their brittleness. Thus, the results of this work will help to manufacture complex shapes with porous areas in zirconia, when the DIW technology is employed.
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Rufo-Martín, Celia, José Díaz-Álvarez e Diego Infante-García. "Influence of PMMA 3D Printing Geometries on the Mechanical Response". Key Engineering Materials 958 (5 de outubro de 2023): 31–39. http://dx.doi.org/10.4028/p-9tor3c.
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This work presents a study regarding the mechanical characterization of polymethyl methacrylate (PMMA) patterned samples manufactured via material-extruded additive manufacturing. In recent years, literature about mechanical analysis in additive manufacturing has been growing increasingly, especially for material extrusion-based techniques. However, this trend surpasses the speed of information released by standard councils, existing no clear specifications for polymer characterization apart from conventional techniques. This issue has led to premature breakage as well as fracture not located in the constant cross-section region of samples. The main purpose of this present research is focused on the analysis of diverse modifications of the standard injection geometries to tackle the mentioned problems. Several printing methodologies were compared, changing slicing and geometrical parameters such as number of walls, and fillet radius. Then, the manufacturing of PMMA samples with a material extrusion printer took place to characterize both the material and the effective properties of the structures. With the information post-processed from tensile and compression tests, disparities were found between different geometrical designs for both elastic modulus and ultimate stress. Moreover, diverse location of fractures were observed for the studied geometries. The data obtained from the analysis was valuable to establish a proper protocol for further studies. The experiments suggest that for tensile tests the golden standard is selecting rectangular specimens since they do not induce premature breakage nor fracture outside of gauge length.
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Graziano, Laurent, Simone Santandrea e Daniele Sciannandrone. "Polynomial axial expansion in the Method of Characteristics for neutron transport in 3D extruded geometries". EPJ Web of Conferences 153 (2017): 06027. http://dx.doi.org/10.1051/epjconf/201715306027.
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Mitchell, Kellen, Lily Raymond e Yifei Jin. "Material Extrusion Advanced Manufacturing of Helical Artificial Muscles from Shape Memory Polymer". Machines 10, n.º 7 (22 de junho de 2022): 497. http://dx.doi.org/10.3390/machines10070497.
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Rehabilitation and mobility assistance using robotic orthosis or exoskeletons have shown potential in aiding those with musculoskeletal disorders. Artificial muscles are the main component used to drive robotics and bio-assistive devices. However, current fabrication methods to produce artificial muscles are technically challenging and laborious for medical staff at clinics and hospitals. This study aims to investigate a printhead system for material extrusion of helical polymer artificial muscles. In the proposed system, an internal fluted mandrel within the printhead and a temperature control module were used simultaneously to solidify and stereotype polymer filaments prior to extrusion from the printhead with a helical shape. Numerical simulation was applied to determine the optimal printhead design, as well as analyze the coupling effects and sensitivity of the printhead geometries on artificial muscle fabrication. Based on the simulation analysis, the printhead system was designed, fabricated, and operated to extrude helical filaments using polylactic acid. The diameter, thickness, and pitch of the extruded filaments were compared to the corresponding geometries of the mandrel to validate the fabrication accuracy. Finally, a printed filament was programmed and actuated to test its functionality as a helical artificial muscle. The proposed printhead system not only allows for the stationary extrusion of helical artificial muscles but is also compatible with commercial 3D printers to freeform print helical artificial muscle groups in the future.
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Kothavade, Premkumar, Abdullah Kafi, Chaitali Dekiwadia, Viksit Kumar, Santhosh Babu Sukumaran, Kadhiravan Shanmuganathan e Stuart Bateman. "Extrusion 3D Printing of Intrinsically Fluorescent Thermoplastic Polyimide: Revealing an Undisclosed Potential". Polymers 16, n.º 19 (2 de outubro de 2024): 2798. http://dx.doi.org/10.3390/polym16192798.
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Thermoplastic polyimides (TPIs) are promising lightweight materials for replacing metal components in aerospace, rocketry, and automotive industries. Key TPI attributes include low density, thermal stability, mechanical strength, inherent flame retardancy, and intrinsic fluorescence under UV light. The application of advanced manufacturing techniques, especially 3D printing, could significantly broaden the use of TPIs; however, challenges in melt-processing this class of polymer represent a barrier. This study explored the processability, 3D-printing and hence mechanical, and fluorescence properties of TPI coupons, demonstrating their suitability for advanced 3D-printing applications. Moreover, the study successfully 3D-printed a functional impeller for an overhead stirrer, effectively replacing its metallic counterpart. Defects were shown to be readily detectable under UV light. A thorough analysis of TPI processing examining its rheological, morphological, and thermal properties is presented. Extruded TPI filaments were 3D-printed into test coupons with different infill geometries to examine the effect of tool path on mechanical performance. The fluorescence properties of the 3D-printed TPI coupons were evaluated to highlight their potential to produce intricately shaped thermally stable, fluorescence-based sensors.
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Nikfarjam, F., Y. Cheny e O. Botella. "The LS-STAG immersed boundary/cut-cell method for non-Newtonian flows in 3D extruded geometries". Computer Physics Communications 226 (maio de 2018): 67–80. http://dx.doi.org/10.1016/j.cpc.2018.01.006.
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Ferro, Paolo, Alberto Fabrizi, Hamada Elsayed e Gianpaolo Savio. "Multi-Material Additive Manufacturing: Creating IN718-AISI 316L Bimetallic Parts by 3D Printing, Debinding, and Sintering". Sustainability 15, n.º 15 (2 de agosto de 2023): 11911. http://dx.doi.org/10.3390/su151511911.
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Allowing for complex shape and low energy consumption, 3D printing, debinding, and sintering (PDS) is a promising and cost-effective additive manufacturing (AM) technology. Moreover, PDS is particularly suitable for producing bimetallic parts using two metal/polymer composite filaments in the same nozzle, known as co-extrusion, or in different nozzles, in a setup called bi-extrusion. The paper describes a first attempt to produce bimetallic parts using Inconel 718 and AISI 316L stainless steel via PDS. The primary goal is to assess the metallurgical characteristics, part shrinkage, relative density, and the interdiffusion phenomenon occurring at the interface of the two alloys. A first set of experiments was conducted to investigate the effect of deposition patterns on the above-mentioned features while keeping the same binding and sintering heat treatment. Different sintering temperatures (1260 °C, 1300 °C, and 1350 °C) and holding times (4 h and 8 h) were then investigated to improve the density of the printed parts. Co-extruded parts showed a better dimensional stability against the variations induced by the binding and sintering heat treatment, compared to bi-extruded samples. In co-extruded parts, shrinkage depends on scanning strategy; moreover, the higher the temperature and holding time of the sintering heat treatment, the higher the density reached. The work expands the knowledge of PDS for metallic multi-materials, opening new possibilities for designing and utilizing functionally graded materials in optimized components. With the ability to create intricate geometries and lightweight structures, PDS enables energy savings across industries, such as the aerospace and automotive industries, by reducing component weight and enhancing fuel efficiency. Furthermore, PDS offers substantial advantages in terms of resource efficiency, waste reduction, and energy consumption compared to other metal AM technologies, thereby reducing environmental impact.
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Cai, Yuanzhi, e Lei Fan. "An Efficient Approach to Automatic Construction of 3D Watertight Geometry of Buildings Using Point Clouds". Remote Sensing 13, n.º 10 (17 de maio de 2021): 1947. http://dx.doi.org/10.3390/rs13101947.
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Recent years have witnessed an increasing use of 3D models in general and 3D geometric models specifically of built environment for various applications, owing to the advancement of mapping techniques for accurate 3D information. Depending on the application scenarios, there exist various types of approaches to automate the construction of 3D building geometry. However, in those studies, less attention has been paid to watertight geometries derived from point cloud data, which are of use to the management and the simulations of building energy. To this end, an efficient reconstruction approach was introduced in this study and involves the following key steps. The point cloud data are first voxelised for the ray-casting analysis to obtain the 3D indoor space. By projecting it onto a horizontal plane, an image representing the indoor area is obtained and is used for the room segmentation. The 2D boundary of each room candidate is extracted using new grammar rules and is extruded using the room height to generate 3D models of individual room candidates. The room connection analyses are applied to the individual models obtained to determine the locations of doors and the topological relations between adjacent room candidates for forming an integrated and watertight geometric model. The approach proposed was tested using the point cloud data representing six building sites of distinct spatial confirmations of rooms, corridors and openings. The experimental results showed that accurate watertight building geometries were successfully created. The average differences between the point cloud data and the geometric models obtained were found to range from 12 to 21 mm. The maximum computation time taken was less than 5 min for the point cloud of approximately 469 million data points, more efficient than the typical reconstruction methods in the literature.
Teses / dissertações sobre o assunto "3D extruded geometries"
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Le, Bars Arthur. "Surface characteristics scheme for the neutron transport equation in extruded and non-conformal 3D geometries". Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASP162.
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Le travail de la thèse se compose de deux parties. La première partie se focalise sur le développement d’un schéma (transport + accélération) aux caractéristiques linéaire surfacique pour la résolution de l’équation du transport sur des géométries 3D extrudées. À présent, seule l’approximation constante peut être utilisée. La différence entre les deux méthodes réside dans le fait que pour l’une la vitesse de convergence au maillage est linéaire (approximation constante) alors qu’elle est quadratique pour l’autre méthode (approximation surfacique linéaire). Pratiquement, la dernière méthode permet de réaliser des calculs avec une même précision qu’avec l’approximation constante tout en réduisant le nombre de mailles, et donc le temps de calcul. Le schéma doit aussi permettre de développer le flux sur une base polynomiale dans la direction axiale, et les sections efficaces ; ce qui importe si l’on veut faire des calculs en évolution. Notez que contrairement à la plupart des approximations linéaires, la source, dans ce schéma, est définie sur les surfaces verticales des régions de calcul. La valeur de la source sur les surfaces horizontales est obtenue à partir d’une interpolation linaire au vol entre les valeurs définies sur les surfaces verticales. L’avantage de cette approche est de pouvoir se débarrasser de l’intégration par le traçage des grandeurs définies sur les surfaces horizontales. Un bilan sur les moments volumiques du flux angulaire est utilisé pour tester la convergence des itérations internes. A cette fin, un opérateur géométrique est défini de manière à construire une source volumique à partir de la source surfacique. La conservation par région est forcée par correction. Concernant l’accélération du transport, le choix a été fait d’implémenter une accélération synthétique de type DPn. La méthode repose sur le développement sur la base des harmoniques sphériques du flux angulaire définie sur les surfaces d’une région de calcul mais peut être vu comme un préconditionnement d’un schéma itératif de type Richardson. Plusieurs arguments motivent ce choix. Le rayon spectral de l’opérateur associé à l’accélération est inférieur à d’autres accélérations comme la diffusion synthetic acceleration (DSA) ou des accélérations non-linéaires de type Coarse mesh finite difference (CMFD), y compris pour des milieux à fort chemins optiques. Par ailleurs, la construction du système d’équation repose sur la même discrétisation spatiale que le transport et limite la nécessité d’une normalisation de certaines grandeurs d’intérêts qui pourraient apparaître avec d’autres méthodes. Enfin, l’utilisation de la forme intégrale du transport rend la méthode attractive pour son utilisation sur des configurations géométriques complexes et des maillages non-structurées. La seconde partie porte sur la correction d’instabilités numériques qui apparaissent lorsque l’on augmente l’ordre de développement spatial du flux. En milieu homogène infini, le terme de fuite issue de l’équation intégro-différentielle doit être nul. Ce n’est pas le cas pour des régions de calcul où la quantité de cordes avec un chemin optique suffisamment faible dépasse une certaine limite. Ce phénomène pénalise la convergence des méthodes du TDT-MOC et la rend impossible s’il est trop important. Ces travaux sont vérifiés sur différentes configurations géométriquesThe thesis work consists of two parts. The first part focuses on developing a linear surface characteristics scheme (transport + acceleration) for solving the transport equation on extruded 3D geometries. Currently, only the constant approximation can be used. The difference between the two methods lies in the fact that the convergence speed for the mesh is linear (constant approximation) for one, whereas it is quadratic for the other method (linear surface approximation). Practically, the latter method allows calculations with the same accuracy as the constant approximation while reducing the number of meshes, and thus the computation time. The scheme should also allow the flux to be developed on a polynomial basis in the axial direction, as well as cross sections, which is important for depletion calculations. Note that unlike most linear approximations, the source in this scheme is defined on the vertical surfaces of the calculation regions. The value of the source on the horizontal surfaces is obtained from an on-the-fly linear interpolation between the values defined on the vertical surfaces. The advantage of this approach is to eliminate the need for tracking-based integration of quantities defined on the horizontal surfaces. A balance on the volume moments of the angular flux is used to test the convergence of the inner iterations. To this end, a geometric operator is defined to construct a volume source from the surface source. Conservation per region is enforced by correction. Regarding transport acceleration, the choice was made to implement a DPn-type synthetic acceleration. The method is based on the spherical harmonics expansion of the angular flux defined on the surfaces of a calculation region but can be seen as a preconditioning of a Richardson-type iterative scheme. Several arguments motivate this choice. The spectral radius of the operator associated with the acceleration is lower than other accelerations such as diffusion synthetic acceleration (DSA) or nonlinear accelerations like Coarse Mesh Finite Difference (CMFD), including for media with high optical paths. Furthermore, the construction of the equation system relies on the same spatial discretization as the transport and limits the need for normalization of certain quantities of interest that might appear with other methods. Finally, the use of the integral form of transport makes the method attractive for use in complex geometric configurations and unstructured meshes. The second part deals with correcting numerical instabilities that appear when increasing the spatial development order of the flux. In an infinite homogeneous medium, the leakage term from the integro-differential equation should be zero. This is not the case for calculation regions where the number of chords with sufficiently low optical paths exceeds a certain limit. This phenomenon penalizes the convergence of TDT-MOC methods and makes it impossible if it is too significant. These works are verified and tested on different geometric configurations
Capítulos de livros sobre o assunto "3D extruded geometries"
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Gorobets, A., F. X. Trias, M. Soria, C. D. Pérez-Segarra e A. Oliva. "From extruded-2D to fully-3D geometries for DNS: a Multigrid-based extension of the Poisson solver". In Lecture Notes in Computational Science and Engineering, 219–26. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-14438-7_23.
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Peterson, Eric, e Bhavleen Kaur. "Printing Compound-Curved Sandwich Structures with Robotic Multi-Bias Additive Manufacturing". In Computational Design and Robotic Fabrication, 526–36. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-8405-3_44.
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AbstractA research team at Florida International University Robotics and Digital Fabrication Lab has developed a novel method for 3d-printing curved open grid core sandwich structures using a thermoplastic extruder mounted on a robotic arm. This print-on-print additive manufacturing (AM) method relies on the 3d modeling software Rhinoceros and its parametric software plugin Grasshopper with Kuka-Parametric Robotic Control (Kuka-PRC) to convert NURBS surfaces into multi-bias additive manufacturing (MBAM) toolpaths. While several high-profile projects including the University of Stuttgart ICD/ITKE Research Pavilions 2014–15 and 2016–17, ETH-Digital Building Technologies project Levis Ergon Chair 2018, and 3D printed chair using Robotic Hybrid Manufacturing at Institute of Advanced Architecture of Catalonia (IAAC) 2019, have previously demonstrated the feasibility of 3d printing with either MBAM or sandwich structures, this method for printing Compound-Curved Sandwich Structures with Robotic MBAM combines these methods offering the possibility to significantly reduce the weight of spanning or cantilevered surfaces by incorporating the structural logic of open grid-core sandwiches with MBAM toolpath printing. Often built with fiber reinforced plastics (FRP), sandwich structures are a common solution for thin wall construction of compound curved surfaces that require a high strength-to-weight ratio with applications including aerospace, wind energy, marine, automotive, transportation infrastructure, architecture, furniture, and sports equipment manufacturing. Typical practices for producing sandwich structures are labor intensive, involving a multi-stage process including (1) the design and fabrication of a mould, (2) the application of a surface substrate such as FRP, (3) the manual application of a light-weight grid-core material, and (4) application of a second surface substrate to complete the sandwich. There are several shortcomings to this moulded manufacturing method that affect both the formal outcome and the manufacturing process: moulds are often costly and labor intensive to build, formal geometric freedom is limited by the minimum draft angles required for successful removal from the mould, and customization and refinement of product lines can be limited by the need for moulds. While the most common material for this construction method is FRP, our proof-of-concept experiments relied on low-cost thermoplastic using a specially configured pellet extruder. While the method proved feasible for small representative examples there remain significant challenges to the successful deployment of this manufacturing method at larger scales that can only be addressed with additional research. The digital workflow includes the following steps: (1) Create a 3D digital model of the base surface in Rhino, (2) Generate toolpaths for laminar printing in Grasshopper by converting surfaces into lists of oriented points, (3) Generate the structural grid-core using the same process, (4) Orient the robot to align in the direction of the substructure geometric planes, (5) Print the grid core using MBAM toolpaths, (6) Repeat step 1 and 2 for printing the outer surface with appropriate adjustments to the extruder orientation. During the design and printing process, we encountered several challenges including selecting geometry suitable for testing, extruder orientation, calibration of the hot end and extrusion/movement speeds, and deviation between the computer model and the physical object on the build platen. Physical models varied from their digital counterparts by several millimeters due to material deformation in the extrusion and cooling process. Real-time deviation verification studies will likely improve the workflow in future studies.
Trabalhos de conferências sobre o assunto "3D extruded geometries"
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Bars, Arthur, Simone Santandrea e Sandra Dulla. "Surface Characteristics Scheme for Solving the Transport Equation in Extruded and Unstructured 3D Geometries". In International Conference on Physics of Reactors (PHYSOR 2024), 820–29. Illinois: American Nuclear Society, 2024. http://dx.doi.org/10.13182/physor24-43563.
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Sethy, Girija Kumari, e Raghu V. Prakash. "Understanding Progressive Buckling in Extruded Square Tubes Using Multiple Measurement Techniques". In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-65484.
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Thin walled structures are widely used as energy absorbing devices during accidents, collisions in various transportation systems. Designing an energy absorbing device requires proper combination of geometry and material. The deformation behavior and collapse modes of these structures are complex. Simple geometries with square, polygonal or circular cross section deform with various collapse modes for energy absorption in these structures. In the present work, square extruded Aluminum tubes are axially compressed under quasistatic loading. Infra-red thermal imaging is done to measure the rise in surface temperature during axial compression of the square tube. Post experimental investigations have been conducted using Scanning Electron Microscope (SEM) and Computerized Tomography (CT) scan to understand the deformation behavior at micro level. The out of plane displacement after progressive buckling is measured using a Coordinate Measuring Machine (CMM). Full field 3D Digital image correlation (DIC) technique has been used to measure the surface strain. The results indicate a good correlation between displacements measured by DIC technique and CMM. Strain field developed during progressive buckling suggests large strains at crumple zones. SEM investigations suggest material pile-up at severely compressed regions with thinning on tensile deformation edges.
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Cleeman, Jeremy, Alex Bogut, Brijesh Mangrolia, Adeline Ripberger, Arad Maghouli, Kunal Kate e Rajiv Malhotra. "Multiplexed 3D Printing of Thermoplastics". In ASME 2022 17th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/msec2022-80882.
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Abstract Extrusion-based additive manufacturing of large thermoplastic structures has significant emerging applications. The most popular approach to economically achieving such 3D printing is to increase the polymer flow rate along with the layer height and line width. However, this creates a fundamental compromise between the achievable geometric fidelity and the printing throughput. We explore a Multiplexed Fused Filament Fabrication (MF3) approach in which an array of FFF extruders concurrently prints different sections of the same part using small layer heights and line widths. Mounting all the extruders on one cartesian gantry without individual control of each extruder’s motion enables simple machine construction and control. 3D geometric complexity is realized by rastering the extruder array across the smallest rectangle bounding each 2D layer and by spatially specific deposition via “dynamic” filament retraction/ advancement in the extruders. The dynamic moniker is because, unlike conventional single extruder FFF, the extruder array does not stop during dynamic filament retraction/advancement. This achieves higher throughput at greater resolution without material-intensive overprinting and machining, geometrically-limited throughput of the dual-extruder strategy, cost and geometric limitations of robot-based multiplexing, and the complexity and geometric limitations of previous gantry-based multiplexing efforts. Our experiments reveal the parameters that affect dynamic retraction and advancement, and show a previously unknown coupling between the efficacy of dynamic filament retraction and dynamic filament advancement. We create part-scale thermal simulations to model temperature evolution in the part under the action of multiple concurrently acting extruders, revealing a unique temperature history that can affect bonding and mechanical properties. We show that MF3 can enable resilience to extruder failure by allowing other extruders to take over part fabrication while the damaged extruder is being replaced. We also demonstrate that MF3 enables flexibility in part scale and geometry, i.e., the ability to make multiple smaller parts of similar or distinct geometries in one production run and lesser number of larger parts of similar or distinct geometries in the next production run. Finally, we quantitatively analyze the future potential of MF3 to achieve similar or greater throughput than state-of-the-art Big Area Additive Manufacturing while significantly enhancing the geometric resolution.
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Ang, Karl Jin, Katherine S. Riley, Jakob Faber e Andres F. Arrieta. "Switchable Bistability in 3D Printed Shells With Bio-Inspired Architectures and Spatially Distributed Pre-Stress". In ASME 2018 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/smasis2018-8208.
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Using fused deposition modeling (FDM) 3D printing, we combine a bio-inspired bilayer architecture with distributed pre-stress and the shape memory behavior of polylactic acid (PLA) to manufacture shells with switchable bistability. These shells are stiff and monostable at room temperature, but become elastic and bistable with fast morphing when heated above their glass transition temperature. When cooled back down, the shells retain the configuration they were in at the elevated temperature and return to being stiff and monostable. These programmed deformations result from the careful design and control of how the filament is extruded by the printer and therefore, the resulting directional pre-stress. Parameter studies are presented on how to maximize the pre-stress for this application. The shells are analyzed using nonlinear finite element analysis. By leveraging the vast array of geometries accessible with 3D printing, this method can be extended to complex, multi-domain shells, including bio-inspired designs.
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Lontos, A., K. D. Bouzakis, G. Demosthenous e A. Baldoukas. "FEM Simulation of the Whole Circle of Aluminum Hot Extrusion Using Circular Dies With Different Extrusion Angle". In ASME 8th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2006. http://dx.doi.org/10.1115/esda2006-95026.
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On of the most typical forming processes used for the production of long, straight semi-finished products in the form of various section geometries is extrusion. Hot extrusion is a thermo-mechanical process whish involves complicated interactions between process parameters, tooling and deforming material /1,2/. In the present paper, FEM simulation is performed in the aluminum extrusion using circular dies with different geometries in order to extract quantitative simulating results regarding various forming parameters. Most specifically the parameters that are investigated are the die design-geometry, the process parameters (i.e. ram speed, container temperature, billet temperature) and the product quality (i.e. extruded shape, surface condition). The finite element modeling is based on 3D simulation tools using the DEFORM 3D software /3–5/. The used work piece is the aluminum AA6061 in cylindrical form with a diameter of 14 mm. The used material for the extrusion die is the hot work steel AISI H13. The geometry of the die is circular with a variation in die angle. The container and the billet temperature will vary from 450 to 550 degrees, and the mandrel (ram) speed will be at the range of 2 mm/sec. On the basis of simulating results such as pressure distribution on the extrusion die, effective stresses on the billet and product quality, new and improve die geometry will be introduced. Although the simulation problem is an axisymmetric one the authors decide to proceed with 3D FEM simulation in order to examine and verify the 3D simulating results. This paper is the first part of a further research project in which more complicated die geometries will be used as simulating and experimental specimens. In addition to simulating results, experimental results will be presented in the next few months.
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Prša, Jelena, Franz Irlinger e Tim C. Lueth. "Algorithm for Detecting and Solving the Problem of Under-Filled Pointed Ends Based on 3D Printing Plastic Droplet Generation". In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-36573.
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In this paper the problem of under-filled pointed ends is introduced and mathematically defined. To tackle this problem, we present a new algorithm that detects and fills the critical areas, which arise at the 3D printed plastic parts. While printing the contours and/or infill lines, due to the limitations based on the width of the extruded material, narrow edges and pointed ends remain improperly filled. This eventually results in 3D printed objects with the final geometry that differs greatly from the initial geometry. This paper presents the fundamentals for solving the problem of 3D printing of geometries which contain narrow pointed ends. The critical area of the pointed ends is mathematically defined and, depending on the angle, the formulae for the calculation of under-filled and over-filled areas are given. The newly developed algorithm, based on the 3D Printing plastic droplet generation process, assures that the droplets of the repeating contours are placed at the edges of the contour-segments and by that minimises the potential under-fills. Furthermore, an additional number of droplets is defined, that are either printed in or removed from the under-filled areas in the angle bisector. The proposed algorithm is applied on parts, whose geometry describes pointed ends. The final 3D printed parts are very appealing and their shape resembles the original geometry more than the final shape of the parts without applying the algorithm.
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Lischke, Fabian, e Andres Tovar. "Design of Self-Supported 3D Printed Parts for Fused Deposition Modeling". In ASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/detc2016-60569.
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One of the primary challenges faced in Additive Manufacturing (AM) is reducing the overall cost and printing time. A critical factor in cost and time reduction is post-processing of 3D printed (3DP) parts, of which removing support structures is one of the most time consuming steps. Support is needed to prevent the collapse of the part or certain areas under its own weight during the 3D printing process. Currently, the design of self-supported 3DP parts follows a set of empirical guide lines. A trial and error process is needed to produce high quality parts by Fused Depositing Modeling (FDM). The usage of chamfer angle with a max 45° angle form the horizontal for FDM is a common example. Inclined surfaces with a smaller angle are prone to defects, however no theoretical basis has been fully defined, therefore a numerical model is needed. The model can predict the problematic areas at a print, reducing the experimental prints and providing a higher number of usable parts. Physical-based models have not been established due to the generally unknown properties of the material during the AM process. With simulations it is possible to simulate the part at different temperatures with a variety of other parameters that have influence on the behavior of the model. In this research, analytic calculations and physical tests are carried out to determine the material properties of the thermoplastic polymer Acrylonitrile - Butadiene - Styrene (ABS) f or FDM at the time of extrusion. This means that the ABS is going to be extruded at 200°C to 245°C and is a viscous material during part construction. Using the results from the physical and analytical models, i.e., Timoshenko’s modified beam theory for micro-structures, a numerical material model is established to simulate the filament deformation once it is deposited onto the part. Experiments were also used to find the threshold for different geometric specifications, which could then be applied to the numerical model to improve the accuracy of the simulation. The result of the finite element analysis is compared to experiments to show the correlation between the prediction of deflection in simulation and the actual deflection measured in physical experiments. A case study was conducted using an application that optimizes topology of complex geometries. After modeling and simulating the optimized part, areas of defect and errors were determined in the simulation, then verified and and measured with actual 3D prints.
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DOJAN, CARTER, MORTEZA ZIAEE e MOSTAFA YOURDKHANI. "RAPID AND SCALABLE ADDITIVE MANUFACTURING OF THERMOSET POLYMER COMPOSITES". In Proceedings for the American Society for Composites-Thirty Seventh Technical Conference. Destech Publications, Inc., 2022. http://dx.doi.org/10.12783/asc37/36457.
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Additive manufacturing (AM) has recently been transformed into a robust manufacturing paradigm for rapid, cost-effective, and reliable manufacturing of fiberreinforced thermoset polymer composites. Among various AM techniques, direct ink writing (DIW) technique offers exceptional ability for constructing scalable 3D composite structures with a high resolution and rapid production rates. In the conventional DIW technique, composite parts are created by thermal post-curing of a thermoset resin ink in an oven at elevated temperatures to obtain a highly crosslinked polymer network. The long and energy-intensive curing processes often required for curing the monomer limits the applications of this approach to layer-by-layer printing of simple 2D geometries. In addition, the conventional approach is not suited to creating large structures, as the uncured material in the earliest deposited layers reaches a flow state, resulting in loss of print fidelity or even the collapse of printed parts. Alternative in-situ curing approaches during the printing process are promising for highrate and scalable AM of thermoset polymer composites. To date, a handful of AM techniques based on in-situ curing have been developed using UV-curable thermoset resins. However, these techniques are not yet applicable for creating structural components due to the poor mechanical performance of the matrix, as well as incomplete curing of the resin in the presence of light absorbing reinforcements. In this work, we present a novel technique that can realize fast and energy-efficient fabrication of high-performance polymer composites using a thermoresponsive thermoset resin system. Our technique involves feeding resinous inks filled with discontinuous carbon fiber (CF) reinforcements from the nozzle of a printing robot and directing thermal stimulus toward the extruded material. The thermal stimulus is configured to rapidly and locally heat the composite material and instantaneously rigidize the extruded material. Using our novel printing technique, we demonstrate AM of tall composite structures using conventional layer-by-layer printing, which is difficult to achieve using existing techniques. In addition, instantaneous and localized curing of the thermoset matrix resin allows for the manufacturing of freeform structures (in-air printing), eliminating the need for support materials and tooling. We have shown that we can manufacture fully cured, void-free, and high-performance composites with printing speeds up to 1.5 m/min without requiring post‐treatment or post‐curing steps.
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Bae, Heechang Alex, Mickenzie Kinney, Tyler Scheff, Matthew Michaelis e Awlad Hossain. "Investigating the Effects of Acetone Vapor Treatment Conditions and Post Drying Methods on Surface Roughness and Tensile Strength of 3D Printed ABS Components". In ASME 2023 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/imece2023-113811.
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Abstract Additive manufacturing (AM) or 3D printing is a fabrication process, usually layer upon layer, of joining materials to make the desired objects directly from a 3D model. 3D printing allows for complex geometries that would be difficult, if not impossible to create using traditional subtractive methods such as milling, grinding, casting, etc. The nature of the additive process also allows the user to avoid or minimize costs that would be incurred if setting up with a traditional subtractive process. With AM there is no need for fixtures, tooling, or multiple processes to complete the part, which allows AM processes to operate with greater flexibility and lower costs. This flexibility allows 3D printing to produce end-use products for many different applications with lower initial investment, maintenance, labor costs and operating costs. Our research specifically focuses on the Fused Deposition Modeling (FDM) process. Fused Deposition Modeling is a process in which the chosen filament is melted, extruded through a nozzle, and then deposited layer by layer as described above. This FDM process is used not only in rapid prototyping as it was initially intended, but also in mass production of finished products as it holds many advantages over the traditional methods. In 3D printing, parts are usually built in discrete layers, and this often results in a certain amount of structural uncertainty in the form of discontinuities, voids, and poor inter-layer bonding. The 3D printed parts are increasingly being used for end-use products that are subject to higher tolerance, quality, uniformity, and surface finish requirements. Hence, to see greater market penetration, the amount of structural uncertainty must be reduced. In our previous research, we successfully investigated the differences in the ultimate strength and fatigue life for 3D printed Acrylonitrile Butadiene Styrene (ABS) components built by various build/layer orientations. Our previous research also successfully highlighted the ultimate strengths and fatigue life, including SN Curves. However, there is a need for further research to improve the surface finish and the tensile strength of the 3D printed ABS components. This research explores the effects of the surface treatment on the tensile strength of the 3D printed ABS components with various layup-orientation. In this study, Acetone Vaper Smoothing (AVS) was used as the surface treatment of the 3D printed ABS components. Our research found that the AVS method reduces stress concentration and structural uncertainty of the 3D printed ABS components to improve the tensile strength. However, these results only occurred after optimizing the acetone vapor exposure and improving the drying methods since acetone can weaken the layer bonding of the ABS and reduced the tensile strength of the 3D printed ABS components in certain situations. This research also provides the optimal conditions of the acetone vapor exposure time and the drying method.
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Alrashdan, Abdulrahman, William Jordan Wright e Emrah Celik. "Light Assisted Hybrid Direct Write Additive Manufacturing of Thermosets". In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-24525.
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Abstract In the past recent years, numerous studies have been conducted on additive manufacturing of thermosets and thermoset composites. Thermosets are an important class of polymers used in engineering applications. Monomer units in these material systems irreversibly cross-link when external stimuli or a chemical crosslinking agent is applied in terms of the curing or photopolymerization process. Thermally curing thermosets mark unique mechanical properties including, high temperature resistance, strong chemical bond, and structural integrity and therefore these materials find wide range of applications currently. However, direct write additive manufacturing of these material systems at high resolution and at complex geometries is challenging. This is due to the slow curing rate of thermally curing thermoset polymers which can adversely affect the printing process, and the final shape of the printed object. On the other hand, VAT Polymerization additive manufacturing, which is based on curing the photopolymer resin by Ultraviolet (UV) light, can allow the fabrication of complex geometries and excellent surface finish of the printed parts due to the fast curing rate of photopolymers used in this technique. Mechanical properties of photopolymers, however, are usually weaker and more unstable compared to the thermally curing polymers used in the direct write additive manufacturing method. Therefore, this study focuses on taking the advantages of these two thermoset additive manufacturing methods by utilizing both the thermally cured epoxy and photopolymer resins together. Using the direct writing, the resin mixture is extruded though a nozzle and the final 3D object is created on the print bed. Simultaneously, the deposited ink is exposed to the UV light enhancing the yield strength of the printed material and partially curing it. Therefore, thermally cured epoxy is used to obtain the desirable mechanical properties, while the addition of the photopolymer resin allows the thermoset mixture to partially solidify the printed ink when exposed to the UV light. The results achieved in this study showed that, the hybrid additive manufacturing technology is capable of fabricating complex and tall structure which cannot be printable via additive manufacturing method. In addition, mechanical properties of the hybrid thermoset ink are comparable to the thermally cured thermoset polymer indicating the great potential of the light-assisted, hybrid manufacturing to fabricate mechanically strong parts at high geometrical resolution.