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['Roy, N.K.', 'Cullinan, M.A.'] | 2021-10-19T18:11:26Z | 2021-10-19T18:11:26Z | 2015 | Mechanical Engineering | null | https://hdl.handle.net/2152/89314 | eng | 2014 International Solid Freeform Fabrication Symposium | Open | ['nanopowders', 'powder spreading', 'actuating system', 'powder bed', 'μ-SLS'] | μ-SLS of Metals: Design of the Powder Spreader, Powder Bed Actuators and Optics for the System | Conference paper | https://repositories.lib.utexas.edu//bitstreams/e7c270bf-07d5-4ac4-8554-3b5ac721e8ca/download | University of Texas at Austin | Nanopowders have a tendency to form agglomerates due to high surface energy and the
presence of attractive van der Waals forces. To overcome this problem, we present a powder
spreading mechanism design that can alleviate this phenomenon by using vibration compaction
to produce a uniform powder distribution in the bed. Most SLS machines employ either a roller
or a blade to spread the powder over the powder bed. However, in order to achieve layer
thicknesses of few microns, a new design for the spreading mechanism which includes a
combination of a precision blade and a precision roller is employed. Also, the design of a linear
actuating system for displacing the powder bed with resolution of few tens of nanometers is
presented for the μ-SLS system. Finally, the paper presents a novel optical system that can
drastically increase the throughput of the system .The detailed design of these systems are
presented in this paper. | null | null | null | null | null | null |
['Roy, N.K.', 'Yuksel, A.', 'Cullinan, M.A.'] | 2021-10-20T22:33:47Z | 2021-10-20T22:33:47Z | 2015 | Mechanical Engineering | null | https://hdl.handle.net/2152/89377 | eng | 2015 International Solid Freeform Fabrication Symposium | Open | ['micro-scale selective laser sintering', 'μ-SLS', 'nanopowders', 'copper', 'particle size', 'density'] | μ-SLS of Metals: Physical and Thermal Characterization of Cu- Nanopowders | Conference paper | https://repositories.lib.utexas.edu//bitstreams/44872607-430d-4595-8cb4-37740d20f7ba/download | University of Texas at Austin | Micro-scale selective laser sintering(μ-SLS) requires the use of nanoparticles(NPs) since
the particle size needs to be an order of magnitude smaller than the melt pool in order to
accurately sinter particles together to form a part. Most NPs properties are dependent upon size
and thus, an exhaustive study of the physical and thermal properties of these NPs is required in
order to successfully model and simulate the sintering process. In this paper we will present
particle size characterization using Scanning electron microscopy (SEM), density measurements
using He pycnometry, and X-ray Energy Dispersive Spectroscopy that were carried out to
characterize the copper(Cu) nanopowder samples. Furthermore, the samples were sintered with
different powers to estimate optimum power and exposure times and the results have been
discussed along with further scope of work for fully characterizing the particles. | null | null | null | null | null | null |
['Wächter, Julian', 'Elsner, Maike', 'Moritzer, Elmar'] | 2021-11-18T01:51:17Z | 2021-11-18T01:51:17Z | 2019 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90401', 'http://dx.doi.org/10.26153/tsw/17322'] | eng | 2019 International Solid Freeform Fabrication Symposium | Open | ['PEEK', 'processability', 'weld seam strength', 'fused deposition modeling'] | Investigation of the Processability of Different PEEK Materials in the FDM Process with Regard to the Weld Seam Strength | Conference paper | https://repositories.lib.utexas.edu//bitstreams/a36b468c-7062-476b-87f8-582433c28b95/download | University of Texas at Austin | Due to the great popularity of the Fused Deposition Modeling (FDM) process, the material market is
growing. In particular, processing of high-temperature materials such as PEEK is demanding.
The aim of the investigations is to test different PEEK materials regarding their processability in the FDM process.
An unreinforced PEEK, a thermally conductive PEEK as well as a carbon fiber reinforced PEEK are investigated.
The processability is assessed with the help of the weld seam strength. The assessment of the weld seam strength
is carried out by building tests. For this purpose, a special method developed at the DMRC is used. In addition, a
welding width factor between the strands deposited on each other is calculated and compared. Finally, a welding
factor is determined to enable the comparison between the different materials. With this procedure, the influences
of varying nozzle and build chamber temperatures on the achievable weld seam strengths are evaluated. | null | null | null | null | null | null |
['Wimmer, Marco', 'Kemnitzer, Jan', 'Forster, David', 'Schorzmann, Johann', 'Dopper, Frank'] | 2024-03-25T22:24:38Z | 2024-03-25T22:24:38Z | 2023 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/124320', 'https://doi.org/10.26153/tsw/50928'] | en_US | 2023 International Solid Freeform Fabrication Symposium | Open | ['HSS', 'PBF-P', 'PEBA', 'additive manufacturing'] | Investigation of the Processability of Polyether Block Amide in High Speed Sintering | Conference paper | https://repositories.lib.utexas.edu//bitstreams/676a37fd-aab9-4e08-832f-4c0d8c96a018/download | University of Texas at Austin | The High Speed Sintering (HSS) process ranks among the processes of Powder Bed
Fusion of polymers (PBF-P) of Additive Manufacturing (AM). Its scalability, constant layer
time and high quality of complex parts compared to other AM processes are some of the
characteristics of the HSS showing its potential for series production for small to medium series.
Most of the investigations for the PBF-P processes were conducted using commercially
available materials like Polyamide 12 (PA12), Polyamide 6 (PA6), Thermoplastic polyurethane
(TPU), Polypropylene (PP) and Polybutylene terephthalate (PBT). This work reports from the
processing of Polyether block amide (PEBA) in HSS. As a block-copolymer on amide basis,
PEBA shows higher performance compared to other block-copolymers like TPU: The high
elastic properties, low density and high service temperature make PEBA an ideal material for
the use in the athletic footwear and outdoor industry. Until now, no research was conducted on
processing PEBA powder in HSS. This work focusses on the material analysis of PEBA powder
and manufacturing of specimens of varying sets of process parameters using methods of Design
of Experiments (DoE) and IFINAM TPA powder from Evonik. Based on a predictive model,
parameter sets for optimum mechanical properties, dimensional accuracy and overall part
properties of HSS PEBA parts were optimised within the framework of this work. | null | null | null | null | null | null |
['Ravichander, B.B.', 'Farhang, B.', 'Ganesh-Ram, A.', 'Hanumantha, M.', 'Ramachandra, S.', 'Shinglot, Y.', 'Amerinatanzi, A.', 'Shayesteh Moghaddam, N.'] | 2021-12-06T22:34:18Z | 2021-12-06T22:34:18Z | 2021 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90700', 'http://dx.doi.org/10.26153/tsw/17619'] | eng | 2021 International Solid Freeform Fabrication Symposium | Open | ['laser powder bed fusion', 'reinforcement', 'IN718', 'microstructure', 'Vickers hardness'] | Investigation of the Properties of Reinforced IN718 Structures Fabricated using Laser Powder Bed Fusion | Conference paper | https://repositories.lib.utexas.edu//bitstreams/25885333-3604-4965-88c2-b64a4f0031b7/download | University of Texas at Austin | Inconel 718 (IN718) superalloy, known for its high strength and corrosion resistant behavior, is
widely used in the aerospace and automotive industries. Laser power bed fusion (LPBF), one of
the commonly used techniques of additive manufacturing, enables the fabrication of structures
with a variety of local properties. Using the same material, components with spatially varying
properties can be fabricated through applying different processing parameters. In this study, IN718
composite structures were fabricated using four types of rod reinforcements with different
geometry. A different set of process parameters was used to fabricated reinforcing rods compared
to that of the main part. The bonding quality at the interface between the main part and
reinforcements was determined by defect analysis on the microstructure results. Also, Vickers
hardness test was performed at the interface in order to examine the mechanical properties of the
samples. It was found out that a similar level of densification and hardness value, slightly less than
the plain sample, can be achieved using helical and arc reinforcing rods. By contrast, significantly
lower density and hardness were observed for the sample reinforced by square rods compared to
the plain sample. | null | null | null | null | null | null |
['Zhou, Y.', 'Zhou, X.', 'Teng, Q.', 'Wei, Q.S.', 'Shi, Y.S.'] | 2021-10-20T21:53:28Z | 2021-10-20T21:53:28Z | 2015 | Mechanical Engineering | null | https://hdl.handle.net/2152/89371 | eng | 2015 International Solid Freeform Fabrication Symposium | Open | ['selective laser melting', '316L stainless steel', 'Inconel 718', 'functionally graded materials', 'powder bed', 'powder feed'] | Investigation of the Scan Strategy and Property of 316L Stainless Steel-Inconel 718 Functionally Graded Materials Fabricated by Selective Laser Sintering | Conference paper | https://repositories.lib.utexas.edu//bitstreams/4883d255-505a-4a17-ba72-520e877df0fc/download | University of Texas at Austin | 316L stainless steel and Inconel 718 alloy functionally graded materials were
fabricated by selective laser melting with a novel approach which combined powder-bed with powder-feed pattern. Two different scanning strategies have been used to form
the steel/Ni FGMs. The interfacial characteristics were analyzed by scanning electron
microscopy and energy dispersive spectroscopy. Quantitative evidence of good bonding
at the interface was obtained from the tensile and shear tests of the steel/Ni FGMs. | null | null | null | null | null | null |
['Yang, Li', 'Haijun, Gong', 'Dilip, Samuel', 'Stucker, Brent'] | 2021-10-13T21:02:45Z | 2021-10-13T21:02:45Z | 2014 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88784', 'http://dx.doi.org/10.26153/tsw/15718'] | eng | 2014 International Solid Freeform Fabrication Symposium | Open | ['thin features', 'direct metal laser sintering', 'lightweight structures', 'additive manufacturing'] | An Investigation of Thin Feature Generation in Direct Metal Laser Sintering Systems | Conference paper | https://repositories.lib.utexas.edu//bitstreams/067fe6bb-ad91-4a5b-aa22-6839005cfb61/download | University of Texas at Austin | The fabrication of metal structures with thin features (<1mm) with additive manufacturing processes is
of interest for various lightweight applications. This paper investigates the geometrical and
microstructural characteristics of thin features fabricated using an EOS direct metal laser sintering
(DMLS) system. Both 1D and 2D thin features were fabricated using various process themes, and
subsequently analyzed for microstructure geometrical characteristics. It was found that the selection of
process parameters has significant influence on both the geometrical accuracy and the microstructure of
the thin features. The results can be used for the further development of process guidelines for
lightweight structures such as cellular structures and support structures. | null | null | null | null | null | null |
['Fan, Foxian', 'Jalui, Sagar', 'Lajoie, Nicholas', 'Manogharan, Guha'] | 2023-02-10T14:27:02Z | 2023-02-10T14:27:02Z | 2022 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/117454', 'http://dx.doi.org/10.26153/tsw/44335'] | eng | 2022 International Solid Freeform Fabrication Symposium | Open | ['AM Post-Processing', 'AM Areal Surface Roughness', 'Mass Finishing', 'Centrifugal Disc Finishing', 'AM Wear Behavior', 'Hybrid Manufacturing'] | Investigation of Wear Behavior of Centrifugal Disc Finishing on Additively Manufactured Ti6Al4V Samples | Conference paper | https://repositories.lib.utexas.edu//bitstreams/ef4d9b99-5f74-441d-a9dc-0660cbfba0d2/download | null | As-built Additively Manufactured (AM) metallic parts require secondary processing in
most applications to improve surface finish and mechanical strength. Mass Finishing (MF)
processes are gaining popularity as effective and economical surface improvement methods for
metal AM parts. This study investigates the wear behavior of post-processing both Laser Powder
Bed Fusion (LPBF) and Electron Beam Melting (EBM) fabricated Ti6Al4V parts via Centrifugal
Disc Finishing (CDF). Both AM orientation-based surface finish and wear behavior are compared
for better understanding on key mechanisms of AM+MF hybrid manufacturing system. The areal
surface roughness results showed that wear rate on side surfaces were higher than top surfaces for
both LPBF and EBM samples in CDF. In addition, LPBF samples exhibited higher material
removal than EBM samples based on weight loss measurements. | null | null | null | null | null | null |
['Mollah, Md. Tusher', 'Moetazedian, Amirpasha', 'Gleadall, Andy', 'Yan, Jiongyi', 'Alphonso, Wayne Edgar', 'Comminal, Raphaël', 'Šeta, Berin', 'Lock, Tony', 'Spangenberg, Jon'] | 2023-01-26T15:51:41Z | 2023-01-26T15:51:41Z | 2022 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/117321', 'http://dx.doi.org/10.26153/tsw/44202'] | eng | 2022 International Solid Freeform Fabrication Symposium | Open | ['Microscale Corner Precision', 'Bowden and Direct-drive Extruders', 'Experiments', 'Computational Fluid Dynamics', 'Material Extrusion Additive Manufacturing'] | Investigation on corner precision at different corner angles in material extrusion additive manufacturing: An experimental and computational fluid dynamics analysis | Conference paper | https://repositories.lib.utexas.edu//bitstreams/333c6c2a-64c3-407c-84e3-e1b4c91ac515/download | null | This paper investigates the influence of different corner angles on microscale geometry in material extrusion
additive manufacturing. Polylactic acid (PLA) was 3D-printed with corner angles of 15°, 30°, 45°, 60°, 75°, 90°,
and 135° using Bowden and Direct-drive extruders. A computational fluid dynamics (CFD) model was developed
to simulate the polymer flow through the extrusion nozzle of both extruders. The simulated corner geometries
were compared with experiments to assess simulation accuracy. This included the primary and secondary mitre
cross-sectional width through the corner point of the 3D-printed strands. This enabled a new understanding about
the prediction accuracy of the CFD model as well as the state of material at the corners, and the deviation of
experimental and simulated corners from the analytical one. Moreover, the amount of over- and under-extrusion
around the corner was estimated for experimental and simulated studies compared with the analytical corner,
which provided fundamental knowledge on corner precision for angular print paths. | null | null | null | null | null | null |
['Yasa, Evren', 'Deckers, Jan', 'Craeghs, Tom', 'Badrossamay, Mohsen', 'Kruth, Jean-Pierre'] | 2021-09-28T19:19:35Z | 2021-09-28T19:19:35Z | 9/15/09 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88158', 'http://dx.doi.org/10.26153/tsw/15099'] | eng | 2009 International Solid Freeform Fabrication Symposium | Open | ['selective laser melting', 'elevated ridges', 'elevated edges', 'successive layers'] | Investigation on Occurrence of Elevated Edges in Selective Laser Melting | Conference paper | https://repositories.lib.utexas.edu//bitstreams/8e3b3ebd-22bb-433a-83b9-a918b3a27871/download | University of Texas at Austin | Selective laser melting (SLM) is a layer-wise material additive process for the direct
fabrication of functional metallic parts. During the process, successive layers of metal powder are
fully molten and consolidated on top of each other by the energy of a high intensity laser beam.
The process is capable of producing almost fully dense three-dimensional parts having
mechanical properties comparable to those of bulk materials. However, one of the problems
encountered in SLM process is the occurrence of elevated ridges of the solidified material at the
edges of the successive layers. Those ridges reduce the dimensional accuracy and topology of the
top surface. The edge-effect problem is encountered not only in SLM, but also in other
production techniques applying melting processes such as LENS® (The Laser Engineered Net
Shaping) and EBM (Electron Beam Melting). In this study, the reasons for elevated edges and
solutions to this problem are investigated and reported. Different scan strategies as well as
different hatching and contour parameters are tested to reduce the edge-effect problem. Besides,
the influence of applying laser re-melting in combination to selective laser melting has been
investigated. It turns out that re-melting layers deposited by SLM improves the part density and
surface roughness, but creates on its own elevated edges. | null | null | null | null | null | null |
['Deng, Dongping', 'Chen, Yong', 'Zhou, Chi'] | 2021-10-06T20:42:30Z | 2021-10-06T20:42:30Z | 2012 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88439', 'http://dx.doi.org/10.26153/tsw/15376'] | eng | 2012 International Solid Freeform Fabrication Symposium | Open | ['PEEK composite', 'mask projection stereolithography', 'slurry recoating', 'sintering'] | Investigation on PEEK Fabrication Using Mask-image-projection-based Stereolithography | Conference paper | https://repositories.lib.utexas.edu//bitstreams/cfe87725-aa7a-428c-aff0-83c49414c95b/download | University of Texas at Austin | This paper presents the findings of an initial study of the fabrication of polyetheretherketone (PEEK)
components based on the mask-image-projection-based Stereolithography (MIP-SL) process. PEEK is a
semicrystalline thermoplastic with excellent mechanical and chemical resistance properties that are
retained to high temperatures. It has been extensively used in the aerospace, automotive, biomedical, and
chemical process industries. The fabrication process based on the MIP-SL includes both green-part
fabrication and the sintering of fabricated green parts. In the green part fabrication, the challenges of
recoating viscous composite slurry are discussed. A prototype system has been developed for the
fabrication of green-parts with complex shapes and small features. Based on the fabricated green-parts,
the challenges in the sintering process for achieving desired functionality are discussed. The test results
on the sintered PEEK components have also been presented. Future work based on the study has been
identified. | null | null | null | null | null | null |
['Praniewicz, M.', 'Fox, J.', 'Saldana, C.'] | 2021-12-01T23:17:39Z | 2021-12-01T23:17:39Z | 2021 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90652', 'http://dx.doi.org/10.26153/tsw/17571'] | eng | 2021 International Solid Freeform Fabrication Symposium | Open | ['lattice structures', 'definition', 'qualification', 'additive manufacturing'] | An Investigation on the Definition and Qualification of Form on Lattice Structures | Conference paper | https://repositories.lib.utexas.edu//bitstreams/c6721a9d-53b6-4402-872a-1d0c0f0fc69d/download | University of Texas at Austin | The lack of uniform qualification techniques for additively manufactured components throughout
industry currently limits their application in high risk environments. This stems from a shortage
of proper tolerancing and product definition to convey design intent and required qualification.
This definition is particularly difficult for complex lattice geometries. The results of studies in
which the form of a lattice component is defined by theoretical supplemental surfaces are
summarized, with specific attention to the role of data sampling in the evaluation of form. A new
case study is presented where techniques borrowed from surface metrology, namely the
construction of a bearing area curve, are used to evaluate the sampling cutoff for form
evaluation. This method is first validated on the nominal geometry of three lattice designs. Initial
results indicate this as a promising methodology. | null | null | null | null | null | null |
['Liu, Bochuan', 'Tuck, Christopher', 'Saleh, Ehab', 'Ashcroft, Ian', 'Wildman, Ricky', 'Hague, Richard'] | 2021-10-12T20:30:54Z | 2021-10-12T20:30:54Z | 2014 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88734', 'http://dx.doi.org/10.26153/tsw/15668'] | eng | 2014 International Solid Freeform Fabrication Symposium | Open | ['multi-functionality', 'multi-layer', 'conductive tracks', 'inkjet printing'] | Investigation on the Performance of Multi-Layer Printed Conductive Tracks on Multi-Layer Printed Insulator | Conference paper | https://repositories.lib.utexas.edu//bitstreams/b9c4f77b-7150-4eff-bd37-457f16051091/download | University of Texas at Austin | The move to multi-functionality in Additive Manufacturing converges a number of
technical challenges, notably the accurate and reliable deposition of different
materials and their interaction. In this paper, an investigation on the pattern quality
and conductivity of multi-layer printed conductive tracks on multi-layer 3D printed
insulator was carried out using a drop-on-demand inkjet technique. Results have
shown that the surface finish of the printed insulator had a significant effect on the
performance of the conductive tracks that have been overlaid. Also the printing
strategy used in the processing resulted different width, height, conductivity and
pattern quality of multi-layer printed conductive tracks. | null | null | null | null | null | null |
['Goulas, Athanasios', 'Southcott-Engstrøm, Daniel', 'Friel, Ross J.', 'Harris, Russell A.'] | 2021-11-01T22:03:04Z | 2021-11-01T22:03:04Z | 2016 | Mechanical Engineering | null | https://hdl.handle.net/2152/89772 | eng | 2016 International Solid Freeform Fabrication Symposium | Open | ['extra-terrestrial materials', 'additive manufacturing', '3D printing'] | Investigation the Additive Manufacture of Extra-Terrestrial Materials | Conference paper | https://repositories.lib.utexas.edu//bitstreams/3dcf26af-83a2-4ccf-bf84-814aa324b829/download | University of Texas at Austin | The Powder Bed Fusion (PBF) additive manufacturing process category, consists of a
group of key enabling technologies allowing the fabrication of both intrinsic and complex
structures for a series of applications, including aerospace and astronautics. The purpose of this
investigation was to explore the potential application of in-space additive manufacturing/3D
printing, for onsite fabrication of structures and parts, using the available extra-terrestrial natural
resources as feedstock. This study was carried out by using simulants of terrestrial origin,
mimicking the properties of those respective materials found extra-terram (in space). An
investigation was conducted through material characterisation, processing and by powder bed
fusion, and resultant examination by analytical techniques. The successful realisation of this
manufacturing approach in an extra-terrestrial environment could enable a sustainable presence in
space by providing the ability to build assets and tools needed for long duration/distance missions
in deep space. | null | null | null | null | null | null |
['Liu, Bochuan', 'Wildman, Ricky', 'Tuck, Christopher', 'Ashcroft, Ian', 'Hague, Richard'] | 2021-10-04T21:24:29Z | 2021-10-04T21:24:29Z | 2011 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88351', 'http://dx.doi.org/10.26153/tsw/15290'] | eng | 2011 International Solid Freeform Fabrication Symposium | Open | ['particle size distribution', 'powder bed', 'processing paramters', 'quality of finishing parts', 'Selective Laser Melting'] | Investigation the Effect of Particle Size Distribution on Processing Parameters Optimisation in Selective Laser Melting Process | Conference paper | https://repositories.lib.utexas.edu//bitstreams/c1438596-fbb8-4e28-ada8-6fa82077e1c5/download | University of Texas at Austin | Selective Laser Melting is an efficient process for producing metal parts with minimal subtractive
post-processing required. Analysis of the parameters controlling the part quality has been
performed focusing on the energy intensity during processing and the effect of the particle size
distribution on factors such as ultimate tensile strength and surface finish. It is shown that the
controlling the energy intensity is key to quality and can be affected by varying, for example,
laser beam diameter or the scanning rate. | null | null | null | null | null | null |
['Weiss, C.', 'Munk, J.', 'Haefner, C.L.'] | 2021-12-06T21:53:56Z | 2021-12-06T21:53:56Z | 2021 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90686', 'http://dx.doi.org/10.26153/tsw/17605'] | eng | 2021 International Solid Freeform Fabrication Symposium | Open | ['powder behavior', 'AlSi10Mg', 'recyclability', 'laser powder bed fusion', 'LPBF'] | Investigation Towards AlSi10Mg Powder Recycling Behavior in the LPBF Process and Its Influences on Mechanical Properties | Conference paper | https://repositories.lib.utexas.edu//bitstreams/63f96a6f-f108-4ad9-b635-fd3e303a3aa0/download | University of Texas at Austin | Parts fabricated by Laser Powder Bed Fusion (LPBF) technique allow for a high
material utilization of a single powder batch, since unfused powder material can be reconditioned
and reused in subsequent manufacturing jobs. Due to process induced spatters however, the
quality of the powder may change during recycling, which in turn can affect the mechanical
properties of built parts. Therefore, a better understanding on the recyclability of the powder
material is needed. Within this work, the powder ageing behavior of the lightweight aluminum
alloy AlSi10Mg in the LPBF process is investigated. A standard build job is developed and built
with ageing powder in 10 consecutive jobs with no refreshing between the cycles. The powder
properties as well as the mechanical properties at static load for two different build
orientations are investigated. The comprehensive analyses suggest that the powder coarsening
may lead to improved mechanical properties during recycling for AlSi10Mg. | null | null | null | null | null | null |
['Krischke, N.', 'Friedmann, M.', 'Fleischer, J.'] | 2023-03-30T16:18:03Z | 2023-03-30T16:18:03Z | 2022 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/117701', 'http://dx.doi.org/10.26153/tsw/44580'] | eng | 2022 International Solid Freeform Fabrication Symposium | Open | ARBURG | Investigations for the Optimization of Metal Freeforming using the ARBURG freeformer | Conference paper | https://repositories.lib.utexas.edu//bitstreams/3d704f8a-532b-4bc3-b8e5-808b1fd8e24e/download | null | The ARBURG freeformer represents an additive manufacturing system for producing
thermoplastic components using commercially available polymer granulate. This fabrication
process offers the potential to use feedstocks known from the metal injection molding (MIM) sector
to manufacture so-called green parts. These parts consist of 60 Vol.-% stainless steel powder and
40 Vol-% organic polymer binding system. By debinding and sintering these green parts, it is
possible to economically produce full metal components with mechanical properties comparable
to metal injection molding. In this publication, the process of producing stainless steel parts with
ARBURG plastic freeforming will be presented. The mechanical properties and part density are
optimized by varying manufacturing parameters and raw materials. Furthermore, concepts to
optimize and increase the service life of the nozzle are shown and discussed. An increase of at least
250% could be achieved by plasma nitriding and coating components of the discharge system. | null | null | null | null | null | null |
['Hecker, F.', 'Elsner, C.L.', 'Hirsch, A.', 'Moritzer, E.'] | 2021-12-01T23:04:41Z | 2021-12-01T23:04:41Z | 2021 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90648', 'http://dx.doi.org/10.26153/tsw/17567'] | eng | 2021 International Solid Freeform Fabrication Symposium | Open | ['arburg plastic freeforming', 'visual properties', 'geometrical properties', 'process parameters', 'optimization'] | Investigations for the Optimization of Visual and Geometrical Properties of Arburg Plastic Freeforming Components | Conference paper | https://repositories.lib.utexas.edu//bitstreams/8d15d057-264b-41ff-8ac5-beaa5df1ebe2/download | University of Texas at Austin | Arburg Plastic Freeforming (APF) is an additive manufacturing process with which three-dimensional, thermoplastic components can be produced layer by layer. Visual and geometrical
properties are a major criterion for characterizing the resulting component quality. The aim of
this study was to investigate the influences on visual and geometrical properties of APF
components depending on process parameters. Initially the focus was on the analysis of the
shrinkage behavior of ABS-M30 (Stratasys). On the basis of the results and an existing
procedure by the machine manufacturer, an optimized procedure for determining the scaling
factors was developed to counteract the shrinkage. With this procedure a higher dimensional
accuracy of the components can be achieved. In addition, it was investigated whether an
adaption of the form factor based on a mathematical model depending on the component
geometry makes sense. The results were transferred into manufacturing guidelines, which allow
the user of the APF-technology to optimize process parameters more efficiently. | null | null | null | null | null | null |
['Jiang, Jinhui', 'Yuan, Mengqi', 'Ji, Tingchao'] | 2021-11-01T21:35:32Z | 2021-11-01T21:35:32Z | 2016 | Mechanical Engineering | null | https://hdl.handle.net/2152/89761 | eng | 2016 International Solid Freeform Fabrication Symposium | Open | ['stab resistance body armor', 'laser sintering', 'structure', 'pyramid'] | Investigations on Laser Sintered Textiles for Stab-Resistant Application | Conference paper | https://repositories.lib.utexas.edu//bitstreams/f1697458-0b40-4329-8b39-da37a80d3612/download | University of Texas at Austin | Stab resistance body armor (SRBA) is essential in protecting people from knife injuries. The
protective parts of traditional SRBA are made of multi-layered ultra-high molecular weight
polyethylene, which causes heavy heat stress for people wearing it. In this paper, the protective
parts of SRBA were manufactured using laser sintering (LS) technology, which provide high
manufacturing flexibility as well as high wearing comfort. Two different structures were
investigated, one is squared plate and the other is pyramid. It was found the pyramid structure
showed much higher stab resistance property then the plate, which is a result from the angle and
thickness effects. This paper is the first effort applying the technology of LS and material of PA
3200 on SRBA, and by applying the pyramid structure on the protective layer of the SRBA, the
total weight could reduce 30-40%. | null | null | null | null | null | null |
['Vora, P.', 'Derguti, F.', 'Mumtaz, K.', 'Todd, I.', 'Hopkinson, N.'] | 2021-10-11T20:34:34Z | 2021-10-11T20:34:34Z | 2013 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88634', 'http://dx.doi.org/10.26153/tsw/15568'] | eng | 2013 International Solid Freeform Fabrication Symposium | Open | ['Additive Manufacturing', 'Selective Laser Sintering', 'Electron Beam Melting', 'metal powder bed', 'in-situ alloy', 'semi-solid processing'] | Investing a Semi-Solid Processing Technique Using Metal Powder Bed Additive Manufacturing Processes | Conference paper | https://repositories.lib.utexas.edu//bitstreams/306d6f58-a927-41df-a64a-8d4e64d27cf6/download | University of Texas at Austin | The work reported investigates in-situ alloying using a semi-solid processing technique with metal
powder bed Additive Manufacturing (AM); in this instance Selective Laser Melting (SLM) and
Electron Beam Melting (EBM) were employed. This technique utilised customised powder blends
that were processed at elevated temperatures. The selection of processing temperature considered
specific alloy solidification ranges. As a result, parts with reduced residual stresses can be produced.
In addition, the use of customised powder blends explored the feasibility of developing alloys specific
to the process/application, thus increasing available material ranges for AM metal powder bed
processes. | null | null | null | null | null | null |
['Zhang, Wei', 'Leu, Ming C.', 'Feng, Chao', 'Ren, Rong', 'Zhang, Renjie', 'Lu, Qingping', 'Jiang, Jubu', 'Yan, Yongnian'] | 2019-09-20T18:10:13Z | 2019-09-20T18:10:13Z | 2000 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/75921', 'http://dx.doi.org/10.26153/tsw/3020'] | eng | 2000 International Solid Freeform Fabrication Symposium | Open | Prototyping | Investment Casting with Ice Patterns Made by Rapid Freeze Prototyping 66 | Conference paper | https://repositories.lib.utexas.edu//bitstreams/82130586-75c0-4c20-8897-357fc53652fb/download | null | One of the most promising applications of rapid freeze prototyping (RFP) is making metal parts by investment casting with the built ice parts. The integration of RFP and investment casting allows fast creation of complex net-shape metal parts directly from their CAD models. The advantages of doing so include no part geometric complexity limitation, no experience of parting line design and assembling needed, clean and low-cost of process operation, and good performance. In this paper, we will present our recent study on binder selection, slurry making, ceramic shell making, and the casting results of the metal parts. | null | null | null | null | null | null |
['Lombardi, John L.', 'Hoffinan, Robert A.', 'Waters, Jason A.', 'Popovich, Dragan'] | 2018-12-05T20:35:18Z | 2018-12-05T20:35:18Z | 1997 | Mechanical Engineering | doi:10.15781/T20K26X7N | http://hdl.handle.net/2152/71415 | eng | 1997 International Solid Freeform Fabrication Symposium | Open | ['FDM', 'EFF'] | Issues Associated with EFF & FDM Ceramic Filled Feedstock Formulation | Conference paper | https://repositories.lib.utexas.edu//bitstreams/6207970d-7d8d-4791-b1ad-e2670ba99380/download | null | null | null | null | null | null | null | null |
['Paggi, Umberto', 'Ranjan, Rajit', 'Thijs, Lore', 'Ayas, Can', 'Langelaar, Matthijs', 'van Keulen, Fred', 'van Hooreweder, Brecht'] | 2021-11-18T18:50:12Z | 2021-11-18T18:50:12Z | 2019 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90465', 'http://dx.doi.org/10.26153/tsw/17386'] | eng | 2019 International Solid Freeform Fabrication Symposium | Open | ['support structures', 'contactless support', 'overheating', 'downfacing regions', 'laser powder bed fusion'] | New Support Structures for Reduced Overheating on Downfacing Regions of Direct Metal Printed Parts | Conference paper | https://repositories.lib.utexas.edu//bitstreams/6e17ba55-1200-4e93-bbc5-83f299542d11/download | University of Texas at Austin | In Laser Powder Bed Fusion (LPBF), the downfacing surfaces usually have increased surface
roughness and reduced dimensional accuracy due to local overheating and warpage. To partially
overcome this a new supporting structure is developed in this study, namely the contactless
support. This is a thin blade parallel to the critical area which transfer the heat away from the melt
pool via conduction through the powder bed instead of direct contact. The support is tested in
different geometries and printing conditions to define the optimal distance from the part and its
effectiveness is evaluated by measuring the surface roughness of the samples. Numerical
modelling of heat transfer phenomenon is also employed to determine the thermal history of the
printing process and understand which parameters define the optimal distance for the thermal
supports. Finally topology optimization is used to create a support structure which minimize the
wasted material while keeping the heat flow optimal. | null | null | null | null | null | null |
['Jandric, Z.', 'Kovacevic, R.'] | 2019-10-09T16:20:52Z | 2019-10-09T16:20:52Z | 2001 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/76154', 'http://dx.doi.org/10.26153/tsw/3243'] | eng | 2001 International Solid Freeform Fabrication Symposium | Open | Optimization | New Way of Process Parameters Optimization in SFF Based on Deposition by Welding | Conference paper | https://repositories.lib.utexas.edu//bitstreams/e4e244c3-026a-4c9d-8b38-bebdf2a07a25/download | null | To successfully control the welding process and to make it appropriate for solid freeform
fabrication (SFF), it is necessary to fully understand the influence of the welding parameters and
the geometry of the substrate on the resulting weld bead dimensions. Extensive experiments
with different welding parameters and complex geometrical features such as edges and corners
have been designed and completed. The experimental data show a clear correlation between the
heat input, the weld bead dimensions, and the two dimensional (2D) geometrical features. This
correlation may be used for on-line welding process control. It is found that the geometry of the
molten pool is directly related to the heat transfer conditions determined by surrounding mass of
material. A machine vision system based on a high-resolution CCD camera coaxially integrated
with a gas tungsten arc welding (GTAW) torch is used to acquire the images of the molten pool.
The results demonstrate the capability to adjust GTAW process parameters according to complex
external and internal geometrical features of the substrate. The heat loss affected by the
surrounding mass of material will be used to determine the optimal energy input. | This work was financially supported by THECB, Grant No. 003613-0022001999, NSF, Grants
No. DMI – 9732848 and DMI – 9809198, and the U.S. Department of Education, Grant No.
P200A-80806-98. | null | null | null | null | null |
['Plocher, J.', 'Panesar, A.'] | 2021-11-09T19:55:13Z | 2021-11-09T19:55:13Z | 2018 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90147', 'http://dx.doi.org/10.26153/tsw/17068'] | eng | 2018 International Solid Freeform Fabrication Symposium | Open | ['beam compliance', 'three-point bending', 'topology', 'fiber orientation', 'lightweight structures', 'fused deposition modeling', 'additive manufacturing'] | Next-Generation Fibre-Reinforced Lightweight Structures for Additive Manufacturing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/9f9cd531-1f2d-41e9-abfa-fddec79ecbd5/download | University of Texas at Austin | In an attempt to realise next-generation lightweight parts and to fully utilize the inherent design
freedom of AM, we propose a topology optimization based design procedure that includes the
anisotropic considerations for continuous fibre printing of variable stiffness composites. In this
paper, we aim to improve the normalized compliance of a beam in a three-point bending scenario,
using a skeletal reinforcement for a topology in which the change in fibre orientation is derived
from the medial axis information. FDM with a dual-nozzle system printing nylon and carbon fibre
filaments were utilized for fabrication. The toolpath i.e. reinforcement strategy available from the
commercial software Eiger® was chosen to imitate the proposed strategy. The numerical
investigation is complemented with experimental tests and a general benchmarking is conducted
using standard pedants. The results have shown improved specific flexural stiffness for samples
with skeletal reinforcement. The skeletal information is therefore considered as important tool for
the retrieval of fibre angles which align with the principle stresses and therefore allow for a more
efficient fibre placement in AM parts for future lightweight end-use parts. | null | null | null | null | null | null |
['Melvin III, Lawrence S.', 'Beaman Jr., Joseph J.'] | 2018-11-08T15:37:28Z | 2018-11-08T15:37:28Z | 1995 | Mechanical Engineering | doi:10.15781/T2KK94Z19 | http://hdl.handle.net/2152/69890 | eng | 1995 International Solid Freeform Fabrication Symposium | Open | ['selective laser sintering', 'intermediate temperature', 'powder application'] | Nickel Applied for Selective Laser Sintering Using a Magnetic Field | Conference paper | https://repositories.lib.utexas.edu//bitstreams/1648bcb6-ba34-4694-94ea-e6df7f963c7a/download | null | Metal powder was applied for the Selective Laser Sintering
process using the sieve feed system and a magnetic field.
The magnetic field had a negative effect on final part quality
as measured by a reduction in final part density. This
negative effect is theorized to be due to the shape and orientation
ofthe magnetic field. It appears possible to change
the field to a benevolent orientation. | null | null | null | null | null | null |
['Yuan, Mengqi', 'Bourerll, David'] | 2021-10-07T15:47:13Z | 2021-10-07T15:47:13Z | 8/16/13 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88486', 'http://dx.doi.org/10.26153/tsw/15420'] | eng | 2013 International Solid Freeform Fabrication Symposium | Open | ['nitrogen flow', 'Laser Sintering', 'part bed surface temperature'] | Nitrogen Flow Effects on Part Bed Surface Temperature during Laser Sintering | Conference paper | https://repositories.lib.utexas.edu//bitstreams/4ca23f1d-1030-4a1a-96d5-d7d4697db441/download | University of Texas at Austin | The role of nitrogen flow rate was invested as it affects the surface temperature of a polymer
laser sintering part bin. A SinterStation 2500® was used for this study. The effect of nitrogen
chamber flow rates between 0.5 and 2.5 m3/hr was observed and compared to the results of a
computational fluids dynamics model. Increasing convective flow generates a uniform reduction
in the surface temperature, but it does not meaningfully reduce surface temperature gradients.
The part bin piston was modified to allow down drafting of nitrogen through the part bin. Down
drafting, while once considered to be effective in accelerating cooling at the end of builds, did
not have a significant effect on the surface temperature profile. | null | null | null | null | null | null |
['Dietrich, Stefan', 'Englert, Lukas', 'Pinter, Pascal'] | 2021-11-09T15:19:29Z | 2021-11-09T15:19:29Z | 2018 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90091', 'http://dx.doi.org/10.26153/tsw/17012'] | eng | 2018 International Solid Freeform Fabrication Symposium | Open | ['porosity analysis', 'x-ray computed tomography', 'laser powder bed fusion', 'metal FFF'] | Non-Destructive Characterization of Additively Manufactured Components Using X-Ray Micro-Computed Tomography | Conference paper | https://repositories.lib.utexas.edu//bitstreams/7a7e5112-1f97-4c1f-b4bd-373b2c0b0b8c/download | University of Texas at Austin | Quality control and microstructure characterization are essential corner stones of the process optimization
through the understanding of process-microstructure-relations in additive manufacturing. The scope of this
work is to investigate the relationships between porosity and the process parameters as well as component
geometry based on X-ray micro-computed tomography data and thus improving the ability for improved
process control. Using test geometries manufactured via laser beam manufacturing and metal fused filament
fabrication in combination with specialized image analysis and data fusion algorithms an extensive analysis of
pore morphology, position and orientation with respect to the printing path could be carried out. The results
show a clear connection between printing strategies as well as part geometry and allow for a direct connection
to mechanical performance characteristics determined by the pore architecture like for example fatigue and
failure behavior. | null | null | null | null | null | null |
['Albakri, Mohammed', 'Sturm, Logan', 'Williams, Christopher B.', 'Tarazaga, Pablo'] | 2021-10-21T19:42:10Z | 2021-10-21T19:42:10Z | 2015 | Mechanical Engineering | null | https://hdl.handle.net/2152/89432 | eng | 2015 International Solid Freeform Fabrication Symposium | Open | ['impedance-based monitoring', 'part abnormalities', 'additive manufacturing', 'quality control'] | Non-Destructive Evaluation of Additively Manufactured Parts via Impedance-Based Monitoring | Conference paper | https://repositories.lib.utexas.edu//bitstreams/58deae40-a995-4137-a483-668276cf6580/download | University of Texas at Austin | The ability of Additive Manufacturing (AM) processes to fabricate complex geometries is
somewhat hindered by an inability to effectively validate the quality of printed complex parts.
Furthermore, there are classes of part defects that are unique to AM that cannot be efficiently
measured with standard Quality Control (QC) techniques (e.g., internal porosity). Current QC
methods for AM are limited to either destructive evaluation of printed test coupons, or expensive
radiation-based scanners of printed parts for non-destructive evaluation. In this paper, the authors
describe their use of impedance-based structural monitoring to indirectly measure printed part
abnormalities. By bonding a piezoceramic (PZT) sensor to a printed part, the measured electrical
impedance of the PZT can be directly linked to the mechanical impedance of the part. By observing
deviations in the mechanical impedance of the part, as determined by this quick, non-intrusive
electrical measurement, one is able to detect the existence of part defects. In this paper, the authors
explore the effectiveness and sensitivity of the technique as a means for detecting of a variety of
defect types and magnitudes. | null | null | null | null | null | null |
['Nomoto, Sukeharu', 'Segawa, Masahito', 'Wakameda, Hiroshi'] | 2021-11-15T20:58:39Z | 2021-11-15T20:58:39Z | 2018 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90269', 'http://dx.doi.org/10.26153/tsw/17190'] | eng | 2018 International Solid Freeform Fabrication Symposium | Open | ['multi-phase field method', 'non-equilibrium', 'thermodynamics', 'machine learning', 'stainless steel', 'solidification', 'additive manufacturing'] | Non-Equilibrium Phase Field Model Using Thermodynamics Data Estimated by Machine Learning for Additive Manufacturing Solidification | Conference paper | https://repositories.lib.utexas.edu//bitstreams/9935fac7-2574-497a-a858-6cc43e24651b/download | University of Texas at Austin | A multi-phase field method using finite interface dissipation model proposed by Steinbach et al. is applied
to simulate solidification microstructure evolution of stainless steel composition in the non-equilibrium condition
of high cooling rate and temperature gradient of additive manufacturing. The calculation is performed for quinary
system in order to simulate solidification of engineering composition. Thermodynamic calculation using
CALPHAD database in this multi-phase field method calculation is replaced by machine learning prediction
procedure to reduce calculation time. The microstructure evaluated by using machine learning parameter is good
agreement with one directly coupled with CALPHAD database. This calculation is approximately five times faster
than the direct CALPHAD calculation method. Finally, it is confirmed that this multi-phase field method can be
applicable to simulate non-equilibrium phase transformation of additive manufacturing condition with high
numerical stabilization. | null | null | null | null | null | null |
['Johnston, S.', 'Anderson, R.', 'Storti, D.'] | 2020-02-21T15:22:35Z | 2020-02-21T15:22:35Z | 8/3/05 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/80061', 'http://dx.doi.org/10.26153/tsw/7083'] | eng | 2005 International Solid Freeform Fabrication Symposium | Open | powder materials | Non-isothermal Initial Stage Sintering Strain Model with Application to 316L Stainless Steel | Conference paper | https://repositories.lib.utexas.edu//bitstreams/b05baddc-e3ba-4d21-a934-406ad7ff6630/download | null | null | null | null | null | null | null | null |
['Hoglund, Robert', 'Smith, Douglas E.'] | 2021-10-21T15:01:53Z | 2021-10-21T15:01:53Z | 2015 | Mechanical Engineering | null | https://hdl.handle.net/2152/89387 | eng | 2015 International Solid Freeform Fabrication Symposium | Open | ['Fused Deposition Modeling', 'topology optimization', 'material distribution'] | Non-Isotropic Material Distribution Topology Optimization for Fused Deposition Modeling Products | Conference paper | https://repositories.lib.utexas.edu//bitstreams/ef78ac66-bf37-42c9-91d4-497aaa849241/download | University of Texas at Austin | Mechanical properties of products produced with the Fused Deposition Modeling (FDM)
process are known to be dependent on bead direction, especially when short fiber reinforcement
is added to the polymer filament feedstock. As a result, the structural performance of fiber-filled
FDM parts is expected to be improved by simultaneously computing preferred deposition
directions while optimizing the internal support structure. This paper presents a topology
optimization method for computing the material distribution within a fiber-reinforced polymer
composite FDM part that incorporates the non-isotropic mechanical properties of the bead
structure. Unlike the well-established homogenization topology optimization method which
determines pointwise orthotropic properties by increasing the complexity of the design problem,
our approach takes advantage of the simplicity of the SIMP method where the underlying
orthotropic orientation is assumed. Computed results show the effect that the orientation of fiber
filled bead orthotropic microstructure has on part topology for 2D FDM parts. | null | null | null | null | null | null |
['Sharma, Maharshi A.', 'Patterson, Albert E.'] | 2024-03-26T20:30:11Z | 2024-03-26T20:30:11Z | 2023 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/124397', 'https://doi.org/10.26153/tsw/51005'] | en_US | 2023 International Solid Freeform Fabrication Symposium | Open | ['FFF process', 'extrusion-based additive manufacturing', 'control systems', 'dynamic modeling'] | Non-Linear Dynamic Modeling of Cartesian-Frame FFF 3-D Printer Gantry for Predictive Control | Conference paper | https://repositories.lib.utexas.edu//bitstreams/e4625159-dac0-4e70-aaa5-458bc219d6dc/download | University of Texas at Austin | This paper presents the development of a dynamic model of an FFF 3-D printer gantry (2-D) that is useful
for developing an open-loop predictive control system. This predictive control system based on the mechanics of the
system will help to reduce manufacturing defects by minimizing position error in the printing head. A six-dimensional
non-linear dynamic model of the printer gantry was derived using Newton-Euler method, followed by a Lagrangian
dynamic model to gain additional insight on energy transfer aspects and model validation. A state-space model of the
full system was developed for positioning and control. A detailed case-study of an example printer was completed in
MATLAB-Simulink to demonstrate the system model with comparisons from the analytical model and physical
characterization on a real printer. Finally, a few examples of passive control designs were illustrated for predictive
control development. It was concluded that dynamics-based predictive control is a promising, realistic, and practical
approach to controlling the dynamic error and dimensional error commonly seen with FFF machines. | null | null | null | null | null | null |
Chen, Yong | 2020-03-09T14:25:05Z | 2020-03-09T14:25:05Z | 8/21/07 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/80184', 'http://dx.doi.org/10.26153/tsw/7203'] | eng | 2007 International Solid Freeform Fabrication Symposium | Open | Stereolithography | Non-Uniform Offsetting and its Applications in Laser Path Planning of Sterolithography Machine | Conference paper | https://repositories.lib.utexas.edu//bitstreams/7861f3c4-a9cb-4e63-b910-14c400f60277/download | null | Laser path planning is an important step in solid freeform fabrication processes such as
Stereolithography (SLA). An important consideration in the laser path planning is to compensate
the shape of laser beam. Currently the compensation is divided into two steps, Z-compensation
and X-Y compensation, and the shape of laser beam is assumed to be uniform for the whole
platform. In this research, we present a sampling based non-uniform offsetting method which
accounts for the different shapes of laser beam at various locations. We discuss the related steps
and algorithms. We demonstrate its effectiveness by using various test cases. Besides
improving the accuracy of SLA machine, non-uniform offsetting can also be applied to address
other accuracy issues caused by thermal and structural variations | null | null | null | null | null | null |
['du Plessis, Anton', 'Yadroitsava, Ina', 'Yadritsev, Igor'] | 2021-11-09T15:15:41Z | 2021-11-09T15:15:41Z | 2018 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90090', 'http://dx.doi.org/10.26153/tsw/17011'] | eng | 2018 International Solid Freeform Fabrication Symposium | Open | ['micro computed tomography', 'microCT', 'bottlenecks', 'additive parts', 'additive manufacturing'] | Nondestructive Micro-CT Inspection of Additive Parts: How to Beat the Bottlenecks | Conference paper | https://repositories.lib.utexas.edu//bitstreams/81203d6d-c4fc-40fd-a8ea-a8f5e3ea357c/download | University of Texas at Austin | Micro computed tomography (microCT) is widely in use for the inspection of additively
manufactured parts. The main use of the technique is to detect unwanted voids inside the part.
However, the ability to detect these kind of defects is strongly affected by image quality, which is
often directly related to the scan time. Selecting fast scan settings (e.g. 5 minutes per part) can work
for many situations where major flaws need to be identified (such as large unmelted cavities), but
this may result in the missing of critical defects which are smaller, such as clustered metallurgical
pores or chains of fine voids between layers or tracks caused lack of fusion . An important defect
type which can be missed by fast scanning is small inclusions also. Possible ways of overcoming
this problem are discussed. After scanning, image analysis requires computing power, time and
skilled human interface for proper analysis. Reduction of the image analysis workflow is possible
using semi-automated analyses and the data size can be reduced using simple methods, including
removal of unwanted data outside the object, 8-bit data size and even .STL format outputs in some
cases. In this paper all the above is discussed in relation to reducing the bottlenecks (problems
causing delays in getting results and slowing the workflow) often associated with microCT. | null | null | null | null | null | null |
['Simeunovic, A.', 'Hoelzle, D.'] | 2021-11-15T21:15:48Z | 2021-11-15T21:15:48Z | 2018 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90275', 'http://dx.doi.org/10.26153/tsw/17196'] | eng | 2018 International Solid Freeform Fabrication Symposium | Open | ['nonlinear model', 'linearized model', 'gray box model', 'direct-write printing', 'extrusion-based additive manufacturing'] | Nonlinear and Linearized Gray Box Models of Direct-Write Printing Dynamics | Conference paper | https://repositories.lib.utexas.edu//bitstreams/928d2bf1-2c6e-477b-8c25-8819d1bc3abc/download | University of Texas at Austin | Control of material metering in material extrusion based additive manufacturing
modalities, such as positive displacement direct-write, is critical for manufacturing accuracy. However, in positive displacement direct-write, transient flows are poorly controlled
due to capacitive pressure dynamics - pressure is stored and slowly released over time from
the build material and other compliant system elements, negatively impacting flow rate startups and stops. Thus far, modeling of these dynamics has ranged from simplistic, potentially
omitting key contributors to the observed phenomena, to highly complex, making usage in
control schemes difficult. Here, we present nonlinear and linearized models that seek to
both capture the capacitive and nonlinear resistive fluid elements of positive displacement
direct-write systems and to pose them as ordinary differential equations for integration into
nonlinear and linear control schemes. We validate our theoretical work with experimental
flow rate and material measurements across a range of extrusion nozzles and materials to address different feature sizes and diverse applications spanning tissue engineering, electronics
fabrication, and food science. As part of this experimental work, we explore the contribution
of the bulk system compliance and the build material compliance to these dynamics. We
show that all models accurately describe the measured dynamics, facilitating ease of integration into future nonlinear and linear control systems. Additionally, we show that while build
material compliance may be nearly entirely reduced through appropriate system design, the
compliance from build material alone is significant enough to require feedback control to
fully control material delivery. | null | null | null | null | null | null |
['Beyene, Shiferaw D.', 'Ayalew, Beshah', 'Pilla, Srikanth'] | 2021-11-18T02:08:06Z | 2021-11-18T02:08:06Z | 2019 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90408', 'http://dx.doi.org/10.26153/tsw/17329'] | eng | 2019 International Solid Freeform Fabrication Symposium | Open | ['NMPC', 'switching systems', 'UV curing', 'additive manufacturing', 'optimal time control'] | Nonlinear Model Predictive Control of UV-Induced Thick Composite Manufacturing Process | Conference paper | https://repositories.lib.utexas.edu//bitstreams/3f04c4a1-74b2-4f21-9904-c632a9b795ee/download | University of Texas at Austin | In this paper the nonlinear model predictive control (NMPC) of UV-induced curing of composite material
for manufacturing of thick parts is proposed. The process involves layer-by-layer curing of thin composite
laminates to form thick part. The model for NMPC switches when a new layer is added to the existing layer. The
layer addition times are determined externally. The offline optimal control is used to determine the optimal time
and temperature profile which will give uniform cure distribution of a thick composite material. Once the
temperature trajectory and optimal time sequences are found, the NMPC is implemented for online control. The
objective is to determine theoretical optimal behavior (assuming the process measurement is available) which
will be used for online switching NMPC for tracking the reference temperature. | null | null | null | null | null | null |
['Brown, R.', 'Morgan, C.T.', 'Majewski, C.E.'] | 2021-11-11T15:38:38Z | 2021-11-11T15:38:38Z | 2018 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90223', 'http://dx.doi.org/10.26153/tsw/17144'] | eng | 2018 International Solid Freeform Fabrication Symposium | Open | ['elastomeric material', 'characterization', 'testing', 'high speed sintering', 'HSS'] | Not Just Nylon... Improving the Range of Materials for High Speed Sintering | Conference paper | https://repositories.lib.utexas.edu//bitstreams/a9a38f02-ac38-4b34-bfe4-5b9e381714c7/download | University of Texas at Austin | High Speed Sintering (HSS) is an emerging, recently commercialised Additive
Manufacturing (AM) process which uses an infrared absorbing ink and infrared lamp to
selectively sinter layers of polymer powder. Currently, Nylon 12 and its composites are used as
the default feedstock due to their large processing windows. However, to meet the increasing
variety of end use applications afforded by the benefits of AM, a wider range of materials must
be developed. This work presents the characterisation and testing of a new elastomeric material
for use in HSS. Parts were produced over a range of processing conditions, varying key
parameters such as part bed temperature, ink density and lamp speed. Performance indicators
including powder recovery, surface roughness and tensile data were evaluated over the range of
conditions tested and all indicated the material’s suitability for use as an HSS material. | null | null | null | null | null | null |
['Schmidt, J.', 'Sachs, M.', 'Fanselow, S.', 'Wirth, K.-E.', 'Peukert, W.'] | 2021-10-27T22:11:26Z | 2021-10-27T22:11:26Z | 2016 | Mechanical Engineering | null | https://hdl.handle.net/2152/89630 | eng | 2016 International Solid Freeform Fabrication Symposium | Open | ['selective laser beam melting', 'polymer powders', 'stirred media milling', 'rounding'] | Novel Approaches for the Production of Polymer Powders for Selective Laser Beam Melting of Polymers | Conference paper | https://repositories.lib.utexas.edu//bitstreams/78b069a3-b39b-4765-a494-3f183b78eac9/download | University of Texas at Austin | The opening of new fields of application of powder-based additive manufacturing methods like selective
laser beam melting of polymers currently is hindered by the limited availability of materials showing good
processability. So far, virtually only polyamides are available as optimized powder materials. Two innovative
methods for production of spherical polymer micro particles for selective laser melting are discussed: The first
approach, stirred media milling and rounding, is applicable for a variety of polymers. It will be exemplarily
discussed for polyesters and the dependency of product properties (particle size distribution, shape,
crystallinity) on the process parameters in the comminution and in the rounding step will be assessed. The
second method, melt emulsification, will be demonstrated for polypropylene. Moreover, the possibilities of dry
coating to tailor particle properties are illustrated. The influence of powder properties on the processability and
on the quality of the obtained devices is outlined. | null | null | null | null | null | null |
['Bandyopadhyay, Amit', 'Atisivan, Raj', 'Bose, Susmita'] | 2019-03-15T16:10:05Z | 2019-03-15T16:10:05Z | 1999 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/73686', 'http://dx.doi.org/10.26153/tsw/828'] | eng | 1999 International Solid Freeform Fabrication Symposium | Open | ['Ceramic materials', 'high strength'] | Novel Ceramics and Metal-Ceramic Composites via Fused Deposition Process | Conference paper | https://repositories.lib.utexas.edu//bitstreams/7c860bc1-c6f3-4f81-a592-3721df5096dc/download | null | Indirect fused·· deposition process is utilized.·.. to ·fabricate controlled porosity ceramic
structures using alumina, mullite, zirconia, LSCF-perovskite, tricalcium phosphate and
hydroxyapatite, where pore size, pore shape and pore connectivity are varied from one end to
the other end of the parts. Some of these porous ceramics are then infiltrated with metals via
pressureless reactive metal infiltration to form novel metal-ceramic composites. Thispaper will
describe processing, structures of various porous and metal-infiltrated composites and their
physical and mechanical properties. | null | null | null | null | null | null |
['Hutton, Logan J.', 'Bartolai, Joseph'] | 2024-03-26T20:04:21Z | 2024-03-26T20:04:21Z | 2023 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/124385', 'https://doi.org/10.26153/tsw/50993'] | en_US | 2023 International Solid Freeform Fabrication Symposium | Open | ['material extrusion', 'infill region', 'additive manufacturing'] | Novel Concepts to Integrate Dense and Sparse Infill Regions in Material Extrusion AM Parts | Conference paper | https://repositories.lib.utexas.edu//bitstreams/b7e146ac-d0b4-4c4a-a7e2-e3ccaeb2ee55/download | University of Texas at Austin | Modern toolpath generation softwares, or “slicers," allow for multiple regions within a Material
Extrusion Additive Manufacturing produced part to be assigned different processing parameters,
including infill density. Contemporary slicers develop these different infill regions independently,
leading to discontinuities in the toolpaths at the region's boundaries. This work investigates the
effect these discontinuities have on part strength, and tests a variety of novel approaches to connect
infill regions in a continuous manner to improve part properties. Mechanical properties of parts
built by toolpaths generated using Ultimaker Cura and Slic3r are compared to those of parts built
using the novel build strategies presented in this work. The continuous and sequential novel build
strategies presented in this work show statistically significant mechanical property increases. | null | null | null | null | null | null |
['Ghazanfari, Amir', 'Li, Wenbin', 'Leu, Ming C.', 'Hilmas, Gregory E.'] | 2021-10-28T20:22:34Z | 2021-10-28T20:22:34Z | 2016 | Mechanical Engineering | null | https://hdl.handle.net/2152/89690 | eng | 2016 International Solid Freeform Fabrication Symposium | Open | ['3D printing', 'extrusion freeforming', 'fused deposition', 'robocasting', 'radiation drying'] | A Novel Extrusion-Based Additive Manufacturing Process for Ceramic Parts | Conference paper | https://repositories.lib.utexas.edu//bitstreams/0a02b858-4dd8-4d57-8fff-616c6e4c1595/download | University of Texas at Austin | An extrusion-based additive manufacturing process, called the Ceramic On-Demand Extrusion
(CODE) process, for producing three-dimensional ceramic components with near theoretical
density is introduced in this paper. In this process, an aqueous paste of ceramic particles with a
very low binder content (<1 vol%) is extruded through a moving nozzle at room temperature. After
a layer is deposited, it is surrounded by oil (to a level just below the top surface of most recent
layer) to preclude non-uniform evaporation from the sides. Infrared radiation is then used to
partially, and uniformly, dry the just-deposited layer so that the yield stress of the paste increases
and the part maintains its shape. The same procedure is repeated for every layer until part
fabrication is completed. Several sample parts for various applications were produced using this
process and their properties were obtained. The results indicate that the proposed method enables
fabrication of large, dense ceramic parts with complex geometries. | null | null | null | null | null | null |
['Graff, K.F.', 'Short, M.', 'Norfolk, M.'] | 2021-09-29T22:47:40Z | 2021-09-29T22:47:40Z | 9/23/10 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88224', 'http://dx.doi.org/10.26153/tsw/15165'] | eng | 2010 International Solid Freeform Fabrication Symposium | Open | ['ultrasonic additive manufacturing', 'Very High Power Ultrasonic Additive Manufacturing System', 'ultrasonic power', 'EWI', 'Solidica™'] | Very High Power Ultrasonic Additive Manufacturing (VHP UAM) for Advanced Materials | Conference paper | https://repositories.lib.utexas.edu//bitstreams/91056bef-026a-47ce-8626-cf6a2986f5d7/download | University of Texas at Austin | To extend current ultrasonic additive manufacturing (UAM) to advanced materials, higher
speeds and larger parts, it was essential to greatly increase the process ultrasonic power. EWI,
with Solidica™, several industry, agency and academic partners, and support of Ohio’s Wright
Program, have developed a “Very High Power Ultrasonic Additive Manufacturing System” that
greatly extends current technology. A key part was the design of a 9.0 kW “push-pull”
ultrasonic system able to produce sound welds in materials such as Ti 6-4, 316SS, 1100 Cu and
Al7075. The VHP system can fabricate parts of up to 1.5m x 1.5m x 0.6m, with process and
software developments that enable forming contoured surfaces. | null | null | null | null | null | null |
['Santangelo, Michael', 'Silwal, Bishal', 'Purdy, Alexander'] | 2021-10-28T20:31:35Z | 2021-10-28T20:31:35Z | 2016 | Mechanical Engineering | null | https://hdl.handle.net/2152/89693 | eng | 2016 International Solid Freeform Fabrication Symposium | Open | ['additive manufacturing', 'wire feed', 'hot-wire GTAW', 'ABAM'] | Vibration Assisted Robotic Hot-Wire Gas Tungsten Arc Welding (GTAW) for Additive Manufacturing of Large Metallic Parts | Conference paper | https://repositories.lib.utexas.edu//bitstreams/4624afa2-3590-442c-8215-9f5853f3ee40/download | University of Texas at Austin | Most of the metal additive manufacturing technologies are focused on high cost and high end applications.
There is in need, a low cost additive manufacturing technology suitable for low and high end metallic applications.
Robotic automated welding can be considered as an alternative to manufactured large scale metal parts with layer
by layer approach. However, many obstacles have to be overcome to make it viable technology in additive
manufacturing industry. A Robotic hot-wire Gas Tungsten Arc Welding (GTAW) with low frequency vibrating
filler wire has been used to deposit a metallic alloy. Different trials of weld-on-bead experiments were performed
to obtain the desired envelop of the melt pool shape for build parts with low manufacturing costs and low build
times. | null | null | null | null | null | null |
['Kandukuri, Shruthika', 'Kashyap, Atharva', 'Lipton, Jeffrey'] | 2023-02-17T14:32:44Z | 2023-02-17T14:32:44Z | 2022 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/117483', 'http://dx.doi.org/10.26153/tsw/44364'] | eng | 2022 International Solid Freeform Fabrication Symposium | Open | sander grips | Vibration Reduction Using Material Jetted Parts for Sander Grips | Conference paper | https://repositories.lib.utexas.edu//bitstreams/3def33ee-5787-44d0-90eb-c9cfb0241c72/download | null | Workers in many industries are exposed to harmful vibrations that negatively impact their
comfort and long-term health through tools such as hand-held sanders. Here we show that using
material jetting we can produce durable and effective vibration protection equipment that reduces
vibrations felt by the user by an average of 23% to 45%. We developed 3D printed vibration
absorbing grips made from a blend of TangoBlack+ and uncured liquid. The grips were deployed
at a Boeing factory and survived 1 month of usage. The grips were best at absorbing higher-
frequency vibrations, able to reduce frequencies above 1kHz by over 20dB. Our results
demonstrate promising capabilities of material jetting viscoelastic materials for direct part
production of ergonomic components. Moreover, these grips could be improved and used to
dampen vibrations on other tools such as bucking bars and used in various other industries. | null | null | null | null | null | null |
['Greeley, Andrew', 'Cormier, Denis'] | 2021-12-07T18:26:45Z | 2021-12-07T18:26:45Z | 2021 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90749', 'http://dx.doi.org/10.26153/tsw/17668'] | eng | 2021 International Solid Freeform Fabrication Symposium | Open | ['directed energy deposition', 'capture effiiciency'] | Vibration-Actuated Powder Dispensing for Directed Energy Deposition Systems | Conference paper | https://repositories.lib.utexas.edu//bitstreams/3973d8e1-2bb5-40ab-96f9-6c37d54fafa6/download | University of Texas at Austin | Users of powder-fed directed energy deposition system often face several challenges
associated with conventional powder delivery sub-systems. In addition to the high cost of wasted
powder, it can be difficult to plan for the amount of material being deposited when some of the
dispensed powder is not captured in the melt pool. This work studies the effectiveness of a
vibration-actuated powder dispensing system using a nozzle with a small capillary opening. The
opening is sized so that particle contact forces arrest powder flow when the vibration actuator is
turned off. The relative effects of vibration frequency, vibration acceleration, nozzle size and
nozzle inclination are compared with the goal of having the output mass flow rate monotonically
change with one of these parameters. For the materials and parameters explored in this study,
nozzle inclination is found to have the largest effect on mass flow rate output and has the desired
monotonically changing relationship. | null | null | null | null | null | null |
Spencer, John D. | 2018-05-03T16:27:48Z | 2018-05-03T16:27:48Z | 1993 | Mechanical Engineering | doi:10.15781/T2DJ5906T | http://hdl.handle.net/2152/65034 | eng | 1993 International Solid Freeform Fabrication Symposium | Open | ['rapid prototyping', 'Department of Manufacturing Engineering and Operations Management', 'stereolithography'] | Vibratory Finishing of Stereolithography Parts | Conference paper | https://repositories.lib.utexas.edu//bitstreams/dfee2f29-d292-4447-a6c4-e20488c13e34/download | null | Rapid Prototype polymer resin models produced by Stereolithography have, by the
nature of the process, a relatively poor surface roughness, particularly on concave and
convex surfaces. In many cases this is unacceptable, and slow and tedious manual finishing
techniques are often used to improve the surface.
An investigation has been conducted into a range of automated finishing techniques
with the aim of producing an acceptable surface roughness. This paper presents the results
from two techniques, Vibratory Bowl Abrasion and Ultrasonic Abrasion using components
made from Ciba-Geigy XB5081-1 and XB 5143 resins.
Initial results from Scanning Electron Microscopy and surface topography analyses
suggest that both techniques are capable of improving the model surfaces. | null | null | null | null | null | null |
['Melvin III, Lawrence S.', 'Das, Suman', 'Beaman Jr., Joseph Jr.'] | 2018-09-26T19:21:21Z | 2018-09-26T19:21:21Z | 1994 | Mechanical Engineering | doi:10.15781/T29P2WR3K | http://hdl.handle.net/2152/68587 | eng | 1994 International Solid Freeform Fabrication Symposium | Open | ['Video microscopy', 'selective laser sintering', 'Optical mangification'] | Video Microscopy of Selective Laser Sintering | Conference paper | https://repositories.lib.utexas.edu//bitstreams/a08b6c48-8c45-427f-9980-7b75a59cef14/download | null | This paper presents the design and implementation
of a video microscopy system that enables real time observation
and archival of selective laser sintering of polymer
and metal materials. The design objectives and selection of
system components are discussed in the first section of this
paper. Experimental results from preliminary experiments
conducted on polycarbonate, wax and nylon powders are
also presented. | null | null | null | null | null | null |
['Choi, S.H.', 'Cai, Y.'] | 2021-09-30T14:28:13Z | 2021-09-30T14:28:13Z | 9/23/10 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88256', 'http://dx.doi.org/10.26153/tsw/15197'] | eng | 2010 International Solid Freeform Fabrication Symposium | Open | ['dual-level reconfigurable additive manufacturing system (DRAMS)', 'digital fabrication', 'process performance', 'system configurations'] | A Virtual Dual-Level Reconfigurable Additive Manufacturing System for Digital Object Fabrication | Conference paper | https://repositories.lib.utexas.edu//bitstreams/76e437a4-2f3a-42aa-a560-b6092ba7089b/download | University of Texas at Austin | This paper proposes a virtual dual-level reconfigurable additive manufacturing system
(DRAMS) for simulation and verification of deposition strategies in digital fabrication of product
prototypes. The DRAMS is aimed to improve additive manufacturing (AM) processes with the
concept of system reconfiguration. It consists of adaptable support and manipulation modules for
deposition of fabrication materials. Topologies are investigated to determine the structures of
these modules, and methods are developed to evaluate and optimize the system configuration.
Simulations show that the DRAMS can not only handle prototypes of different sizes and
fabrication materials, but also increase the process speed. The DRAMS offers an effective tool
for simulation, verification and optimization of deposition strategies under different system
configurations to improve process performance. | null | null | null | null | null | null |
['Gibson, I.', 'Cobb, S.', 'Eastgate, R.'] | 2018-05-03T17:45:45Z | 2018-05-03T17:45:45Z | 1993 | Mechanical Engineering | doi:10.15781/T2QV3CM8T | http://hdl.handle.net/2152/65047 | eng | 1993 International Solid Freeform Fabrication Symposium | Open | ['Department of Manufacturing Engineering and Operations Management', 'Virtual Reality', '3D CAD systems', 'rapid prototyping'] | Virtual Reality and Rapid Prototyping: Conflicting or Complimentary? | Conference paper | https://repositories.lib.utexas.edu//bitstreams/7bb68886-65fd-4650-9fa5-135001b04a85/download | null | It is likely that the uses for virtual reality (VR) will coincide with applications that
rapid prototyping systems have already been used for. VR, with the ability to model real
life environments, presents an ideal base for the design and development of new
manufactured products. As a method of producing physical models directly from 3D CAD
systems, rapid prototyping technology has also been used to visualise new product designs.
This paper attempts to determine whether the two technologies are a means to the same
end or whether they combine to form a more efficient route to product development. | null | null | null | null | null | null |
['Qiu, Dan', 'Langrana, Noshir A.', 'Danforth, Stephen C.', 'Safar, Ahmad', 'Jafar, Mohsen'] | 2019-03-01T17:29:27Z | 2019-03-01T17:29:27Z | 1998 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/73514', 'http://dx.doi.org/10.26153/tsw/664'] | eng | 1998 International Solid Freeform Fabrication Symposium | Open | ['CAD', 'LM'] | Virtual Simulation for Multi-material LM Process | Conference paper | https://repositories.lib.utexas.edu//bitstreams/55891e1e-3100-43f6-8b5b-aadd87201b29/download | null | In an ONR funded MURI program, to improve quality of multi-material parts,
we've been developing an advanced computer simulation for the multi-material layered
manufacturing (LM) process. The CAD models and their .stLfiles are created using. the
commercially available software such as I-DEAS and ProE. Using this information, one
tool path file per material is generated. Our file preparation algorithm, systematically,
layer by layer, integrates all tool path files into one multi-material tool path file. The
results of the multi-material tool path are graphically visualized using the simulation
algorithm (written in c++ & SGI OpenGL). From a virtual simulation, we can check the
LM process, and make the best selection of tool path parameters afterwards. After several
trials from design to simulation, if the simulation result is acceptable, the real
manufacturing can be started. And the part's quality should be better than a part
manufactured without running simulation in advance. This paper will represent .•. new
studies on using real toadshapes to get more realistic simulation results. Many parts have
been successfully simulated using our method. | null | null | null | null | null | null |
['Duty, Chad', 'Ajinjeru, Christine', 'Kishore, Vidya', 'Compton, Brett', 'Hmeidat, Nadim', 'Chen, Xun', 'Liu, Peng', 'Hassen, Ahmed Arabi', 'Lindahl, John', 'Kunc, Vlastimil'] | 2021-11-02T18:14:11Z | 2021-11-02T18:14:11Z | 2017 | Mechanical Engineering | null | https://hdl.handle.net/2152/89854 | eng | 2017 International Solid Freeform Fabrication Symposium | Open | ['viscoelastic model', 'print conditions', 'printability', 'extrusion-based printing'] | A Viscoelastic Model for Evaluation Extrusion-Based Print Conditions | Conference paper | https://repositories.lib.utexas.edu//bitstreams/4e02ec81-20bd-4584-856c-cefafbb69910/download | University of Texas at Austin | Extrusion-based printing systems have improved significantly over the past several years,
allowing for higher throughput, higher temperatures, and larger components. At the same time,
advanced materials are being introduced on the market that can provide improved performance
over a range of operating conditions. Often these materials incorporate fiber reinforcements,
reactive resins, and additives to control reaction kinetics, flow rheology, or thermal stability. This
study presents a general framework for evaluating the printability of various candidate materials
based on a basic viscoelastic model. The model addresses fundamental requirements for extrusion-based printing, including pressure-driven flow, bead formation, bead functionality, and
component-level functionality. The effectiveness of this model for evaluating the impact of
compositional variations and identifying appropriate processing conditions has been demonstrated
for specific materials on direct write, fused filament fabrication, and large-scale extrusion
platforms. | null | null | null | null | null | null |
['Vaish, Apoorv', 'Yang Lee, Shien', 'Valdivia Alvarado, Pablo'] | 2021-11-09T15:38:53Z | 2021-11-09T15:38:53Z | 2018 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90098', 'http://dx.doi.org/10.26153/tsw/17019'] | eng | 2018 International Solid Freeform Fabrication Symposium | Open | ['viscosity control', 'pseudoplastic polymers', 'embedded 3D-printing', 'direct ink writing'] | Viscosity Control of Pseudoplastic Polymer Mixtures for Applications in Additive-Manufacturing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/75c321e5-6461-4dec-9ded-11fc6f235dda/download | University of Texas at Austin | Various additive manufacturing (AM) processes exploit the rheological properties of non-Newtonian (e.g. pseudoplastic) polymers for stability and feature realization. For embedded
3D-printing (e3DP) and direct ink writing (DIW), features are deposited on top or within a layer
of matrix/base material and the rheological properties of the matrix are crucial for satisfactory
prints. Due to their high apparent viscosities under static conditions, these base polymers do not
flow easily when poured in bulk into the fabrication space. Traditionally, manual methods were
employed to spread them into an even layer. In this study, an alternative approach to spread and
level pseudoplastic polymers using oscillatory shear stresses generated by a vibrating actuator
is presented. The proposed approach lowers the viscosity of the polymers, thereby facilitating
gravity-driven flow to generate a flat polymer-air interface. A fluid rheology model detailing
the parameters influencing the process is presented and experiments are performed using these
parameters. | null | null | null | null | null | null |
['Karnati, Sreekar', 'Matta, Niroop', 'Sparks, Todd', 'Liou, Frank'] | 2021-10-07T15:33:00Z | 2021-10-07T15:33:00Z | 2013 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88482', 'http://dx.doi.org/10.26153/tsw/15416'] | eng | 2013 International Solid Freeform Fabrication Symposium | Open | ['laser metal deposition', 'process monitoring', 'thermal camera'] | Vision-based Process Monitoring for Laser Metal Deposition Processes | Conference paper | https://repositories.lib.utexas.edu//bitstreams/0489e5e2-3441-4eda-9170-8c62cd4b05bb/download | University of Texas at Austin | Laser Metal deposition is a process with immense scope and promise for becoming a
robust manufacturing technology in the near future. Monitoring process variables is very
instrumental in process planning and output monitoring. The current work deals with realizing
the effect of power modulation on size of the high temperature region during deposition with
varying powder feed. A thermal camera was used to visualize and analyze the deposition
process. The area of the high temperature region through the deposition was identified and
compared to realize the effect of each variable parameter during deposition. The power
modulation was fruitful in modulating the area of the high temperature zone. Optimum set of
parameters to perform deposition were identified. | null | null | null | null | null | null |
['Adediran, A.I.', 'Nycz, A.', 'Thornton, A.', 'Love, L.J.'] | 2021-11-04T18:52:19Z | 2021-11-04T18:52:19Z | 2017 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90003', 'http://dx.doi.org/10.26153/16924'] | eng | 2017 International Solid Freeform Fabrication Symposium | Open | ['laser metal wire deposition', 'LMD-w', 'image processing', 'visual sensing', 'discontinuities', 'error detection'] | Visual Sensing and Image Processing for Error Detection in Laser Metal Wire Deposition | Conference paper | https://repositories.lib.utexas.edu//bitstreams/76be9105-9e5c-41f7-8440-340220e95ba3/download | University of Texas at Austin | Laser metal deposition with wire (LMD-w) involves feeding metal wire through a nozzle
and melting the wire with a high-power laser. With efficient process control, i.e. sensing,
processing, and feedback correction of errors, the technology has the potential to change the
course of manufacturing. However, the limitation most often encountered in LMD is the
difficulty in controlling the process. Monitoring and control of metal additive manufacturing
processes has been mostly researched on powder-based systems and has not been extensively
investigated on metal wire feed systems. This work proposes a method for detecting
discontinuities in a deposited layer in the LMD-w process via optical inspection and processing
of images obtained from a high-resolution camera. The aim is to develop an effective sensing
module that automatically detects irregularities in each layer before proceeding to subsequent
layers, which will reduce part porosity and improve inter-layer bond integrity. | null | null | null | null | null | null |
['Kattethota, Gautham', 'Henderson, Mark'] | 2019-02-22T19:53:22Z | 2019-02-22T19:53:22Z | 1998 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/73466', 'http://dx.doi.org/10.26153/tsw/616'] | eng | 1998 International Solid Freeform Fabrication Symposium | Open | ['FDM', 'Rapid Prototyping'] | A Visual Tool to Improve Layered Manufacturing Part Quality | Conference paper | https://repositories.lib.utexas.edu//bitstreams/19159cc2-889f-40de-83c0-726c36372b32/download | null | A software tool is described that will aid the user in. choosing the optimum build orientation
to obtain the ..best composite set of surface finishes on a part built .on a Fused Deposition
Modeling (FDM) rapid prototyping machine.• Experiments were conducted to obtain statistical
.surface roughness values as a function of orientation and layer thickness.Three types of surfaces
(features}.have been. considered planar (both upward facing and downward facing (over hang
surfaces)),.quadratic and free form Surfaces..Data analysis of surface roughness of planar surfaces at
various orientations·and their mapping. to. quadratic and freeform surfaces are presented.
decision support software tool allows dynamic .. color-coded visualization of the surface quality
simultaneous with build parameters including orientation and layer thickness. | null | null | null | null | null | null |
['Choi, S.H.', 'Chan, A.M.M.'] | 2019-10-24T18:06:24Z | 2019-10-24T18:06:24Z | 2002 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/77413', 'http://dx.doi.org/10.26153/tsw/4502'] | eng | 2002 International Solid Freeform Fabrication Symposium | Open | Prototyping | Visualization of Surface Accuracy for Virtual Prototyping | Conference paper | https://repositories.lib.utexas.edu//bitstreams/da94f71c-e098-49a4-95df-8dae12baadd3/download | null | This paper introduces a virtual prototyping (VP) system that simulates a RP
process to produce a virtual prototype of a product, which facilitates visual study of
the surface quality of the physical prototype that the RP machine will subsequently
fabricate. The virtual prototype displayed in a computerized virtual environment
allows the designer to analyze the surface texture and accuracy of a product prototype
conveniently. It may be super-imposed on its original design so that all dimensional
deviations are clearly highlighted. The system can further pinpoint the areas in which
the dimensional deviations are out of the acceptable range. The designer can hence
improve the accuracy of the prototype well before physical fabrication by optimizing
the RP fabrication parameters, such as the layer thickness, hatch space and build
orientation, in the system. In this paper, the simulation principles will be described
and case studies will be given to illustrate how the system works. | The authors would like to acknowledge the Research Grant Council of the Hong
Kong SAR Government and the CRCG of the University of Hong Kong for their
financial support for this project. | null | null | null | null | null |
['Campbell, R. Ian', 'Jee, Haeseong J.', 'Lee, H.S.'] | 2019-09-23T16:56:43Z | 2019-09-23T16:56:43Z | 2000 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/75970', 'http://dx.doi.org/10.26153/tsw/3069'] | eng | 2000 International Solid Freeform Fabrication Symposium | Open | Visualization | Visualization Tools for Design Support in SFF 437 | Conference paper | https://repositories.lib.utexas.edu//bitstreams/213867fa-8816-4191-8c2b-4b9719851778/download | null | When considering the use of SFF, there are many questions a designer might ask. What model orientation should be used, will the model have adequate aesthetic and functional properties, is the STL file suitable for transfer to the SFF machine? These questions could be answered by a comprehensive design support system for SFF. This paper addresses a number of components for such a system that can be met through the use of visualization tools. These include: 1. Visualization of surface roughness 2. Visualization of characteristic features (e.g. surface macro-texture) 3. Visual simulation of fabrication Example applications of these tools are presented together with a status review of their implementation to date. It is envisaged that these tools will be incorporated into an already existing network-based preprocessor used for visualization, repair and slicing of STL files. The direction of future work is also discussed which will include the visual representation of functionally graded materials (connected with FEM results). | null | null | null | null | null | null |
['Pegues, Jonathan', 'Roach, Michael', 'Williamson, R. Scott', 'Shamsaei, Nima'] | 2021-11-11T15:08:09Z | 2021-11-11T15:08:09Z | 2018 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90213', 'http://dx.doi.org/10.26153/tsw/17134'] | eng | 2018 International Solid Freeform Fabrication Symposium | Open | ['additive manufacturing', 'fatigue behavior', 'defects', 'fractography'] | Volume Effects on the Fatigue Behavior of Additively Manufactured Ti-6Al-4V Parts | Conference paper | https://repositories.lib.utexas.edu//bitstreams/df161b01-b19f-415f-80e0-b01fc1e03ddf/download | University of Texas at Austin | Recent interest to implement additive manufactured parts into structural applications has created
a critical need to better understand the fatigue behavior of these parts. Alloys such as Ti-6Al-4V
are popular in the aerospace and biomedical industries due to their superior strength to weight ratio
and biocompatibility. In these two industries, part sizes can range from very small surgical
implants to large structural components, all of which are subjected to cyclic loading conditions.
The fatigue behavior of additively manufactured parts may show more sensitivity to part size than
their wrought counterparts due to the defects that are inherent to the fabrication process. This
research investigates the sensitivity of additively manufactured Ti-6Al-4V parts to volume size by
comparing the stress-life fatigue curves of three geometries with increasing gage volumes. Results
indicate that additive Ti-6Al-4V parts show reduced fatigue lives because of an increase in surface
or near-surface defects. | null | null | null | null | null | null |
['Ma, Di', 'Lin, Feng', 'Chua, Chee Kai'] | 2019-03-08T17:50:40Z | 2019-03-08T17:50:40Z | 1999 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/73574', 'http://dx.doi.org/10.26153/tsw/716'] | eng | 1999 International Solid Freeform Fabrication Symposium | Open | ['Rapid prototyping', 'Solid Freeform Fabrication'] | Volume Modeling for Rapid Prototyping | Conference paper | https://repositories.lib.utexas.edu//bitstreams/ea247511-1425-41e7-abfd-b77b4fc20247/download | null | The expanding workspace of Rapid Prototyping will draw on the new developments
in geometric modeling. Volume modeling has substantial advantages over other modeling
schemes to meet the emerging requirements of Rapid Prototyping technology. It provides us with
a new approach to design complex geometry and topology. The integration of the volume
modeling and Rapid Prototyping technology will help us to fully exploit RP's ability to fabricate
objects with complex structures. This paper addresses our research and practice in a volume
modeling system toward Rapid Prototyping. Novel techniques in volumetric data manipulation,
NURBS volume models and triangular facet generation over solid models are presented.
Computer models designed by this system and their corresponding DTM products are also
shown atthe end of this paper. | null | null | null | null | null | null |
['Yim, Soonkyu', 'Gea, Hae Chang'] | 2019-10-18T16:04:01Z | 2019-10-18T16:04:01Z | 2001 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/76246', 'http://dx.doi.org/10.26153/tsw/3335'] | eng | 2001 International Solid Freeform Fabrication Symposium | Open | Voxel-based | Voxel-based Modeling with Multi-resolution Wavelet Transform for Layered Manufacturing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/3857a0d5-4939-429c-8623-a8a36be079ef/download | null | A voxel-based modeling system with multi-resolution for layered manufacturing is presented in
this paper. When dealing with discretized data input, voxel-based modeling shows its clear
advantages over the conventional geometric modeling methods. To increase the efficiency of
voxel data due to its large storage space requirement, multi-resolution method with wavelet
transform technique is implemented. Combining with iso-surface generation and lossless
polygon reduction, this voxel-based modeling method can easily work with layered
manufacturing. To demonstrate these concepts, components with different resolutions are built
using Layered Manufacturing and presented in the paper. | null | null | null | null | null | null |
['Ye, Jennings Z.', 'Sun, Yaxuan', 'Taylor, Hayden'] | 2024-03-26T20:25:16Z | 2024-03-26T20:25:16Z | 2023 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/124395', 'https://doi.org/10.26153/tsw/51003'] | en_US | 2023 International Solid Freeform Fabrication Symposium | Open | ['computed axial lithography', 'surface quality', 'radon transform', 'voxel'] | VOXEL-FREE RADON TRANSFORM FOR IMPROVING SURFACE QUALITY IN COMPUTED AXIAL LITHOGRAPHY | Conference paper | https://repositories.lib.utexas.edu//bitstreams/3a293a2d-ac07-44e7-bd65-c904362eca48/download | University of Texas at Austin | Computed axial lithography (CAL) is an additive manufacturing process that projects light
patterns onto a rotating vial of photosensitive resin to print the desired object through the
superposition of light energy. Currently, these projection patterns are generated by voxelizing a
target object from an STL or another 3D file format and applying the Radon transform through an
iterative optimization process. In this work, a voxel-free method to generate projection sets is
proposed. Here, the Radon transform is performed directly on a non-voxelized target object by
calculating intersections between incident rays of light and triangles of the original STL surface
mesh. Initial simulated results show a more consistent light dose at the surface of the object,
indicating improved surface quality and smoothness. Additionally, simulations show a more
uniform object interior using the proposed method as well as the potential for improved speed
scaling with object size. | null | null | null | null | null | null |