Browsing by Subject "material extrusion"
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Item 3D Printed Fastener-Free Connections for Non-Structural and Structural Applications – An Exploratory Investigation(University of Texas at Austin, 2018) Delgado Camacho, Daniel; Clayton, Patricia; O'Brien, William J.; Jung, Kee YoungThe construction industry has shown increasing interest in AM technologies and has successfully implemented various proof of concept projects using different AM processes. Much of the research on AM in the construction industry has focused on development of new large-scale extrusion printing systems and on development of cementitious materials for AM applications, whereas research exploring new applications of already existing AM technologies and materials suitable for construction applications has been scarce. This paper explores the use of existing, small-scale material extrusion 3D printers to create fastener-free connections that could be used in structural or non-structural applications. These connections, inspired by traditional wood joinery and modern proprietary connections were printed using polylactic acid (PLA) material. The flexural strength of the connections was then tested using a four-point bending test to evaluate their potential structural performance and to identify connection types that warrant further research in this exploratory proof of concept study.Item Additive Manufacturing of Alumina Components by Extrusion of In-Situ UV-Cured Pastes(University of Texas at Austin, 2018) Tsui, Lok-kun; Maines, Erin; Evans, Lindsey; Keicher, David; Lavin, JudithAdditive manufacturing of ceramic materials is an attractive technique for rapid prototyping of components at small scales and low cost. We have investigated the printing of alumina pastes loaded at 70-81.5 wt% solids in a UV curable resin. These can be deposited by extrusion from a syringe head on a Hyrel System 30M printer. The print head is equipped with an array of UV LEDs, which solidify the paste without the need for any applied heating. Parameters optimized include print speed, layer height, applied force, and deposition rate. Using A15 alumina and submicron A16 powder precursors, we can achieve bulk densities of 91% and 96% of theoretical density respectively. The influence of dispersants and surfactants added to the powder on the rheology of the pastes, the print process parameters, and the quality of the final components are also investigated.Item Aligning Material Extrusion Direction with Mechanical Stress via 5-Axis Tool Paths(University of Texas at Austin, 2018) Gardner, J.A.; Nethercott-Garabet, T.; Kaill, N.; Campbell, R.I.; Bingham, G.A.; Engstrøm, D.S.; Balc, N.O.Mechanical properties of parts fabricated via the Material Extrusion (ME) process can be improved by optimising process settings, however, their properties are strongly influenced by build orientation due to the stair-stepping effect initiating cracks whilst under load. 5-axis ME enables the fabrication of parts without the layer-by-layer restrictions that conventional 3-axis strategies impose. By aligning extrusion direction with high stress tensors, 5-axis tool paths can be used to reduce the effects of weak inter-layer bonds. To establish performance differences between parts manufactured by either strategy, wave spring-inspired geometry was selected for production, due to the multi-directional tensile loads acting throughout the material. 5-axis and 3-axis tool paths were generated via the Grasshopper 3D virtual environment within Rhinoceros 3D and MakerBot Desktop, and manufactured using a 5AXISMAKER and a MakerBot Replicator 2, respectively. To evaluate performance differences between the two strategies, compression tests were conducted on the parts.Item A Comparative Study Between 3-Axis and 5-Axis Additively Manufactured Samples and their Ability to Resist Compressive Loading(University of Texas at Austin, 2019) Kaill, N.; Campbell, R.I.; Pradel, P.; Bingham, G.A.One of the main limitations of parts made with Material Extrusion (ME) is their anisotropic mechanical behaviour. This behaviour limits the functionality of these components in multi-directional loading conditions. A critical factor for this mechanical behaviour is the poor bonding between layers. 5-axis ME has the capability to orientate the printed layers in order to limit the effect of poor inter-laminar bonding. Previous studies have investigated 5- axis ME, but not fully explored 5-axis capabilities of this manufacturing technique. To address this gap, this paper compares the mechanical behaviour of 3-axis and 5-axis ME samples when subjected to compressive loading. The results demonstrate how depositing material in “3D layers” can improve the consistency of a sample’s mechanical behaviour. This study indicates that 5-axis ME can enable more isotropic behaviour in printed samples.Item Design and Assessment of an AM Vending Machine for Student Use(University of Texas at Austin, 2013) Meisel, Nicholas A.; Williams, Christopher B.Due to prohibitive costs, access to Additive Manufacturing (AM) technologies at academic institutions tends to be limited to upper-level courses that feature significant project-based coursework, such as capstone design. However, with the decreasing cost of desktop-scale AM technology, there is potential to improve student access to such technologies throughout a student’s undergraduate career, and thus provide more opportunities for AM education. In this poster, the authors present the design and implementation of an AM “vending machine” that is powered by desktop-scale extrusion-based AM systems. The resulting machine allows for unrestricted student use of AM equipment, and thus provides ample opportunity for informal learning regarding AM. The results of a formal assessment of student use of the machine are presented.Item Design and Manufacture of a Continuous Fiber-Reinforced 3D Printed Unmanned Aerial Vehicle Win(University of Texas at Austin, 2021) Jayashankar, Dhileep Kumar; Devarajan, Aarthi; Dong, Guoying; Rosen, DavidThe Markforged Mark Two 3D printer is capable of printing various orientations of continuous fiber reinforcement. An initial study of how the orientation of the fiber influences the strength characteristics (tensile and flexural properties) was conducted. Four combinations of carbon fiber reinforcement orientations were tested, specifically unidirectional, isotropic, concentric and a combination of isotropic and concentric, with the Markforged Onyx matrix material. The results will aid in designing a wing with the optimum fiber configuration that will give the desired mechanical properties based on the forces acting on the wing. Design for Additive Manufacturing (DfAM) concepts and tools will be used to design and manufacture a large UAV wing. Topology optimization, based on a CFD computed pressure distribution, was used to determine geometric regions where carbon fiber reinforcement could be best utilized. From there, a honeycomb structure was designed to ensure stiffness and light weight based on desired densities. A wing section was fabricated using the Mark Two printer to identify the capabilities and limitations of the system in realizing the design objectives.Item Design and Realization of a 6 Degree of Freedom Robotic Extrusion Platform(University of Texas at Austin, 2016) Kubalak, Joseph R.; Mansfield, Craig D.; Pesek, Taylor H.; Snow, Zachary K.; Cottiss, Edward B.; Ebeling-Koning, Oliver D.; Price, Matthew G.; Traverso, Mark H.; Tichnell, L. David; Williams, Christopher B.; Wicks, Alfred L.The layer-wise deposition of Additive Manufacturing (AM) processes allows for significant freedom in the design of product geometry; however, the use of 3-axis deposition tools results in layer interfaces that reduce material properties in the build direction. Adding additional degrees-of-freedom (DOF) to the AM tool could remove this limitation by enabling out of plane material deposition. For example, multi-DOF tool paths could align material extrusion with a part's stress contours to circumvent inter-layer delamination. As a step towards this goal, the authors designed, fabricated, and tested an AM extrusion system that leverages a 6-DOF robotic arm. In this paper, the authors detail the realization of this system including the design of a high-temperature filament extruder, kinematics and tool path generation, and user interface. The performance of the system is evaluated through layered deposition of ABS thermoplastic.Item Design and Simulation of 3D Printed Air-Cooled Heat Exchangers(University of Texas at Austin, 2016) Felber, R.A.; Rudolph, N.; Nellis, G.F.The use of material extrusion with conductive fillers is explored for air-cooled heat exchangers. A general overview of the manufacturing tasks, design criteria, printability constraints, and modeling techniques is given, along with experimental data from prototype testing. The first sub-scale prototype design is an air-water crossflow heat exchanger designed to transfer around 100 Watts. It was printed with unfilled conventional ABS and the air channels designed with an array of round pin fins to enhance heat transfer. The prototype was also CT-scanned for inspection of the printed pin fin shapes.Item Development of a Novel Test Artefact for Conformal Material Extrusion Printing(2022) Jalui, Sagar S.; Zargar, Seyed Hossein; Moroney, Sheila; Putz, Marcus; Taylor, Mychal; Hatch, Serah; Manogharan, GuhaAdditive manufacturing (AM) allows for free complexity. However, the layer-by-layer manufacturing method traditionally relies on a G-code input to the machine, representing 2D planar slices of each layer, which eventually combines to represent the net-shape 3D geometry. Through modification of existing slicer software, thus modifying the G-code input to the machine, non-planar (conformal) shells can be generated on top of a traditional planar scaffolding. The objective of this work is to design a novel test artifact to aid in the creation of design rules and to identify machine limitations for conformal printing. With the use of non-conventional design features using trigonometric (sine) surfaces, this test artifact would allow for deeper insights into the print quality of organic shapes made possible using a commercial, low-cost, material extrusion 3D printer. It would also enable the creation of design rules for conformal printing to push forward the true dual-Design for Additive Manufacturing (dual-DfAM) potential.Item Embedding of Liquids into Water Soluble Materials via Additive Manufacturing for Timed Release(University of Texas at Austin, 2017) Zawaski, Callie; Margaretta, Evan; Stevenson, Andre; Pekkanen, Allison; Whittington, Abby; Long, Timothy; Williams, Christopher B.One fundamental goal of personalized medicine is to provide tailored control of the dissolution rate for an oral dosage pill. Additive manufacturing of oral dose medicine allows for customized dissolution by tailoring both geometric and printed material properties. Direct processing of medicine via filament material extrusion is challenging because many active agents become inactive at the elevated temperatures found in the melt-based process. In this work, this limitation is circumvented by incorporating the active agents via in-situ embedding into a priori designed voids. This concept of embedding active ingredients into printed parts is demonstrated by the in-situ deposition of liquid ingredients into thin-walled, water soluble, printed structures. The authors demonstrate the ability to tune dissolution time by varying the thickness of the printed parts walls using this technique.Item Estimating Strength of Lattice Structure Using Material Extrusion Based on Deposition Modeling and Fracture Mechanics(University of Texas at Austin, 2017) Park, Sang-in; Watanabe, Narumi; Rosen, David W.Geometrical complexity in lattice structures yields large bounding surfaces to be approximated during additive manufacturing (AM) processes. In material extrusion, approximation of geometries using finite-sized thin filaments introduces defects such as voids and gaps in as-fabricated geometries. This initiates cracks between layers and increases possibility of fracture by crack propagation. As a result, a lattice structure fabricated by material extrusion tends to fail at significantly lower stress than estimated strength without consideration of fracture mechanism. The goal of this research is to estimate strength of material extruded lattice structures considering bonding strength among layers. To achieve this, the bonding strength is determined based on a deposition process modeling scheme and fracture mechanics analysis. A two-layer deposition model is generated to investigate deposited geometry, and the effective interlayer-bonding strength is calculated using a cohesive zone model (CZM) and peel tests. The resulting strength is incorporated into the property-estimation procedure.Item EVALUATING THE COMPRESSIVE STRENGTH OF AM RISERS FOR GREEN SAND METALCASTING(University of Texas at Austin, 2023) Hasbrouck, C.R.; Melnik, Samantha A.While many metalcasting foundries have experimented with using additive manufacturing (AM) for patternmaking, the compressive strength of the tapered AM risers for green sand metalcasting has not yet been explored. This study investigates the effects of infill pattern type, infill density, and shell thickness on the compressive strength of a standard 3-inch diameter by 5-inch tall by 3-degree taper cylindrical riser manufactured with PLA using a material extrusion process. The findings for these AM risers include plots and mathematical models of compressive strengths at three different scales of the standard geometry (full, three-quarters, and half), predicted build times and masses using other common infill patterns, potential failure mechanisms during use of AM and conventionally manufactured riser patterns, and considerations on design for both additive manufacturing and green sand metalcasting. It is concluded that AM risers can be incorporated into and perform well as part of conventional green sand metalcasting patterns.Item Exploring the Manufacturability and Resistivity of Conductive Filament Used in Material Extrusion Additive Manufacturing(University of Texas at Austin, 2017) Gao, Harry; Meisel, Nicholas A.Additive manufacturing (AM) has the unique ability to build multifunctional parts with embedded electronics without the need for post-print assembly. However, many existing forms of multifunctional AM are not easily accessible to hobby-level users. Most hobby-level desktop 3D printers are only used with non-conductive filaments. Recently however, conductive filaments have become increasingly available for material extrusion desktop printers. Ideally, the use of these filaments would allow circuitry to be printed simultaneously with the rest of the structure, enabling complex, inexpensive, multifunctional structures. However, the resistivity of conductive filament is significantly impacted by the geometry of the print and the printing parameters used in the build process. In this study, two types of commercially-available conductive filament were tested under a variety of parameters. It was found that print temperature, layer height, and orientation all significantly affect the resistivity in various ways. The knowledge from this research will allow users to design better multifunctional parts that have reduced resistivity.Item G-WING: A NOVEL SOFTWARE TOOL FOR TOOLPATH-CENTRIC DESIGN OF WINGS FOR MATERIAL EXTRUSION(University of Texas at Austin, 2023) Valenti, Justin D.; Bartolai, Joseph; Yukish, Michael A.A novel software tool for the design of small aircraft wings to be fabricated with material extrusion is presented where the key requirement of the tool is to minimize the time from identified need to realized capability. The tool, named G-Wing, uses rapid design algorithms based on lifting line theory to determine the outer-mold line of the wing based on desired aerodynamic behavior. The resulting wing shape and flight-load distribution are given to a structural design algorithm to determine the internal structure of the wing based on both expected flight loads and manufacturing constraints. Finally, manufacturing instructions in the form of G-Code are created directly from the wing shape and internal structure. This process removes explicit geometric modeling and slicing from the critical design path and directly converts airfoil coordinates to perimeter G-Code points, minimizing the introduction of geometric error. This process has been used to design and fabricate multiple small aircraft wings that have successfully flown. G-Code for an example wing section is shown to be lighter and require less build time compared to G-Code generated by a standard CAD-slicing toolchain.Item Influence of Embedding Process on Mechanical Properties of Material Extrusion Parts(University of Texas at Austin, 2016) Sinha, Swapnil; Meisel, Nicholas A.The layer-by- layer deposition of material in Additive Manufacturing (AM) introduces the capability for in-situ embedding of functional components into printed parts. The typical embedding process involves, i) designing the cavity for the embedded component, ii) pausing the print when the top layer of the cavity is reached, iii) manually inserting the component, and iv) resuming the build process. However, the effect of different interfacial materials (due to the presence or absence of a shape converter) and the pause time during the build process on a part’s material properties is not well-understood. Therefore, the tensile strength of 3D-printed embedded specimens with and without shape converters and with different intervals of pause time is tested in this study. The results from this experimental analysis can be useful for the design guidelines for AM with embedded components as they provide an initial understanding of mechanical properties of these parts.Item Investigating Material Degradation Through the Recycling of PLA in Additively Manufactured Parts(University of Texas at Austin, 2017) Tanney, Daniel; Meisel, Nicholas A.; Moore, JacobThe field of additive manufacturing (AM) has been expanding rapidly with the decreasing cost of desktop-scale material extrusion AM systems. As the cost of AM systems decreases, more users are investing in the technology, including universities, which have turned to AM as an option for providing wide-scale access to prototyping technology. However, this type of wide-access printing generates significant waste due to cast-off support material as well as failed prints from inexperienced users. This paper investigates the feasibility of recycling this cast-off material through the relationship between the mechanical properties of recycled PLA and the number of lifecycles it has experienced on a desktop material extrusion machine. A three-stage pelletizing, extrusion, and printing process is used to investigate recycling of PLA material from cast-off build material. Additionally, the research investigates how adding virgin pellets to pellets of the recycled material in various ratios can affect tensile properties.Item Lost-PLA Casting Process Development Using Material Extrusion with Low-Weight PLA(University of Texas at Austin, 2023) Ali, Mohammad Alshaikh; Huseynov, Orkhan; Fidan, Ismail; Vondra, FredThe goal of this research is to develop a baseline procedure for lost-PLA casting process of aluminum. Traditional Manufacturing techniques and Smart Manufacturing techniques have their advantages and disadvantages. Integrating the traditional and modern aspects of manufacturing enhances the capabilities of manufacturing. In this study, low-weight PLA is used in a Material Extrusion (MEX) machine to fabricate sacrificial patterns for an aluminum lost-casting process. Different process parameters, after a calibration process, are tested for the MEX process The MEX process parameters tested are: infill pattern, and top/bottom solid layers. The MEX process parameter investigation allows to draw conclusions to establish a standard for which parameters are ideal for the casting process. For this research, casting process parameters are set constant. The preliminary studies show that the lost-PLA casting process is successful in producing dimensionally accurate aluminum parts by a direct-pour casting process using the suggested MEX process parameters.Item Machine Learning-Assisted Prediction of Fatigue Behaviour in Fiber-Reinforced Composites Manufactured via Material Extrusion(University of Texas at Austin, 2023) Rajeshirke, Mithila; Alkunte, Suhas; Huseynov, Orkhan; Fidan, IsmailThe recent advancements in material extrusion (MEX) have expanded the potential use of polymeric and composite structures in a wide range of structural and load-bearing applications. However, cyclic loads can induce fatigue, resulting in the development of structural damage and potentially leading to catastrophic failure at lower stress levels compared to normal mechanical loading. Therefore, it is crucial to thoroughly investigate and understand the fatigue behavior of composite parts manufactured using MEX. Predicting the fatigue life of polymeric composite components poses a significant challenge due to the complex nature of the materials involved. In this research, the aim is to utilize Machine Learning (ML) techniques to predict the fatigue life of fiber-reinforced composites produced through the MEX process. ML focuses on developing models that can learn from data, recognize underlying patterns within the data, and use those patterns to make accurate predictions or decisions.Item Mechanical Surface Treatment of Polymer Parts Produced by FFF(University of Texas at Austin, 2023) Dietrich, S.; Karcher, B.; Popp, U.; Scholz, J.The surface structure in the form of waviness and roughness as well as near surface density of FFF parts represents a major issue with respect to mechanical performance especially under fatigue loading. Mechanical surface treatments like shot peening or rolling are commonly used techniques, especially for metal components, to reduce surface roughness, increase surface densification and create beneficial residual stress states in the surface layer. In this study, a rolling process has been applied intermittently with the layer-wise FFF process and the effect on the surface state has been investigated using laser scanning and optical microscopy as well as microcomputed tomography. A process window with different rolling tools and rolling paths has been identified and analysed. The results show clearly advantageous properties regarding an improved surface roughness, with a higher densification gradient in the first perimeter tracks of the FFF extrusion strategy as well as sharper corners being realized.Item A Model for Residual Stress and Part Warpage Prediction in Material Extrusion with Application to Polypropylene(University of Texas at Austin, 2016) Watanabe, N.; Shofner, M.L.; Treat, N.; Rosen, D.W.The layer-by-layer fabrication procedure causes residual stresses to accumulate due to the repetition of heating and cooling during the material extrusion process. In this study, residual stress and part warpage of a polypropylene copolymer are investigated. The effects of adjusting process variable settings, such as deposition temperature, deposition speed, and layer height, on part warpage are analyzed computationally and experimentally. Material extrusion process simulation models that are capable of predicting the temperature distributions, deposited filament shapes, and residual stresses of fabricated parts have been developed. These models are used to predict the warpages and deformations of the fabricated parts; these predictions are compared with experimental results to evaluate the models’ efficacy. Insights are gained on the effects of particulate inclusions on the residual stress and warpage behaviors of polypropylene copolymer.