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['Rangapuram, M.', 'Dasari, S.K.', 'Isanaka, S.P.', 'Buchely, M.F.', 'Newkirk, J.W.', 'Chandrashekhara, K.'] | 2023-03-30T16:09:16Z | 2023-03-30T16:09:16Z | 2022 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/117697', 'http://dx.doi.org/10.26153/tsw/44576'] | eng | 2022 International Solid Freeform Fabrication Symposium | Open | Additive manufacturing | Calibration of the Johnson-Cook Material Model for Additively Manufactured 304L SS Parts: Modeling and Experiments | Conference paper | https://repositories.lib.utexas.edu//bitstreams/9b9d708a-c1db-4c0c-a451-32809c81f71d/download | null | Selective laser melting (SLM) is a type of additive manufacturing technique which uses a powder
bed to form complex metal parts in a layer-by-layer process. This study aims to understand the
material flow of parts manufactured by SLM process using 304L stainless steel powder, which is
widely used in numerous applications. The tensile specimens were manufactured using 304LSS
powder through SLM process. Low strain-rates, high temperature tensile tests were carried out to
calibrate the parameters of the constitutive Johnson-Cook strength model. To conduct the tensile
tests, different temperatures (25
oC, 150 oC and 250 oC) and strain-rates (0.1 s-1, 0.01 s-1 and 0.001
s-1) were used. The material model developed was used in numerical simulation of the tensile tests
and compared with the experimental results. | null | null | null | null | null | null |
['Liu, z. E.', 'Ko, T. C.', 'Bes, J.', 'Cawley, J. D.', 'Heuer, A. H.'] | 2018-12-05T18:00:46Z | 2018-12-05T18:00:46Z | 1997 | Mechanical Engineering | doi:10.15781/T2930PF6W | http://hdl.handle.net/2152/71404 | eng | 1997 International Solid Freeform Fabrication Symposium | Open | ['CAM', 'LEM'] | CAM-LEM Processing: Materials Flexibility | Conference paper | https://repositories.lib.utexas.edu//bitstreams/63157cf4-333c-4e65-8fca-3174694a4833/download | null | The cut-then-stack paradigm of computer-aided manufacturing of laminated engineering
materials (CAM-LEM) offers choice of feedstock material, ease of handling finely divided (and
therefore sinterable) powders, and the ability to mix materials. This combination of features was
exploited to process fluidic devices. CAM-LEM processing was used to render the Part in
aluminum oxide, silicon nitride, and stainless steel. | null | null | null | null | null | null |
['Lade, Robert K. Jr', 'Hippchen, Erik J.', 'Rodgers, Luke', 'Macosko, Christopher', 'Francis, Lorraine F.'] | 2021-10-21T22:07:15Z | 2021-10-21T22:07:15Z | 2015 | Mechanical Engineering | null | https://hdl.handle.net/2152/89457 | eng | 2015 International Solid Freeform Fabrication Symposium | Open | ['fused deposition modeling', 'capillary flow', 'microchannel', 'flow dynamics'] | Capillary-Driven Flow in Open Microchannels Printed with Fused Deposition Modeling | Conference paper | https://repositories.lib.utexas.edu//bitstreams/4e98325a-af43-4f0b-8392-09358f0e3a81/download | University of Texas at Austin | The fundamentals of fluid flow in 3D printed, open microchannels created using fused
deposition modeling (FDM) are explored. Printed microchannels are used in microfluidic devices
and have potential applications in embedding electronics in plastic substrates. However, FDM
parts possess rough surfaces, and in this study, surface topography is shown to have an important
impact on flow behavior, causing the liquid to travel down the channel with a characteristic
‘pulsing’ movement. We also analyze the influence of print orientation on capillary flow, where
microchannels printed in specific orientations are shown to exhibit different flow dynamics. | null | null | null | null | null | null |
['Basak, Amrita', 'Das, Suman'] | 2021-10-26T19:56:33Z | 2021-10-26T19:56:33Z | 2016 | Mechanical Engineering | null | https://hdl.handle.net/2152/89569 | eng | 2016 International Solid Freeform Fabrication Symposium | Open | ['MAR-M247', 'nickel-based superalloys', 'scanning laser epitaxy', 'carbide formation'] | Carbide Formation in Nickel-Base Superalloy MAR-M247 Processed Through Scanning Laser Epitaxy (SLE) | Conference paper | https://repositories.lib.utexas.edu//bitstreams/d1203693-1870-4cf3-8ee7-e62dc4af5d63/download | University of Texas at Austin | Nickel-base superalloys develop high-temperature strength primarily due to the solid-solution-strengthening and the precipitation-strengthening mechanisms typically through cobalt/chromium
and aluminum/titanium respectively. Certain other elements such as boron and zirconium are
chosen for grain boundary strengthening. Such elements tend to segregate to the grain boundaries
reducing the grain boundary energy and resulting in better grain boundary cohesion and ductility.
Another form of grain boundary strengthening is achieved through the addition of carbon and
various carbide formers. The carbide formers are responsible for driving precipitation of carbides
at grain boundaries and thereby reducing grain boundary sliding. Various types of carbides such
as blocky, elongated, and Chinese-script are possible in the microstructures of nickel-base
superalloys depending on the composition of the superalloy and processing conditions. However,
in the SLE fabricated MAR-M247, only blocky carbides were predominantly observed. Scanning
electron microscopy and energy dispersive X-ray spectroscopy investigations were carried out and
the carbides were found to be tantalum-rich. | This work is sponsored by the ONR through grant
N00014-14-1-0658. | null | null | null | null | null |
['Bai, Jiaming', 'Goodridge, Ruth D.', 'Hague, Richard J.M.', 'Song, Mo'] | 2021-10-05T15:50:36Z | 2021-10-05T15:50:36Z | 8/22/12 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88397', 'http://dx.doi.org/10.26153/tsw/15336'] | eng | 2012 International Solid Freeform Fabrication Symposium | Open | ['laser sintering', 'polymer nanocomposites', 'processing parameters', 'thermal conductivity'] | Carbon Nanotube Reinforced Polyamide 12 Nanocomposites for Laser Sintering | Conference paper | https://repositories.lib.utexas.edu//bitstreams/cd4ade4e-4d0c-407e-ad28-babd4f450a59/download | University of Texas at Austin | In this work, Polyamide12 (PA12) and Carbon nanotube (CNT) added PA12-CNT
nanocomposites were laser sintered and investigated. The powder morphology and CNT
dispersion of the PA12-CNT were examined. Laser sintering process parameters: powder bed
temperature and laser power were studied and optimised. The effect of the addition of CNT on
the thermal properties of PA12 was identified. Compared to the laser sintered parts produced
from commercially available laser sintering PA12 powder, the laser sintered PA12-CNT parts
showed increased tensile modulus and tensile strength. | null | null | null | null | null | null |
['Jost, Elliott', 'Berez, Jaime', 'Saldaña, Christopher'] | 2023-02-17T14:42:38Z | 2023-02-17T14:42:38Z | 2022 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/117485', 'http://dx.doi.org/10.26153/tsw/44366'] | eng | 2022 International Solid Freeform Fabrication Symposium | Open | Additive manufacturing | A Case Study in Component Redesign for Additive Manufacturing Process Workflows | Conference paper | https://repositories.lib.utexas.edu//bitstreams/00a7bd69-bba3-497e-94ee-a0d6934fd32a/download | null | Additive manufacturing (AM) has matured beyond limited use-cases in rapid prototyping
into a process capable of competing with conventional manufacturing methods in the production
of end-use components. As such, many manufacturers are evaluating candidate products for
redesign for AM, with interest in improving component performance, streamlining manufacturing,
and reducing costs. In this study, the authors argue for systematic use of opportunistic design tools
such as generative design and for the inclusion of restrictions imposed by the entire manufacturing
process workflow to be included in the design process. Emphasis is placed on how secondary
processing steps, that is, those other than the primary AM process, inform design. A bicycle stem
is used as an exemplar case study of component redesign for AM. Generative design is used to
optimize the component’s weight given the design constraints. An end-to-end manufacturing
process chain is consequently developed and analyzed for viability, covering design for additive
manufacturing (DFAM) and post processing. Through this comprehensive case study, it is shown
that significant weight savings, greater than 25% in the present case, can be achieved through the
DFAM process. Guidelines from the DFAM process are generalized for application to further
cases. | null | null | null | null | null | null |
Aubin, Richard F. | 2018-04-19T18:09:14Z | 2018-04-19T18:09:14Z | 1992 | Mechanical Engineering | doi:10.15781/T2HT2GV4P | http://hdl.handle.net/2152/64397 | eng | 1992 International Solid Freeform Fabrication Symposium | Open | ['UTC', 'United Technologies Corporation', 'Pratt & Whitney'] | A Case Study in Rapid Prototyping | Conference paper | https://repositories.lib.utexas.edu//bitstreams/dbdfed3a-5712-4bc5-9b7e-062bbbc9b641/download | null | Since the first quarter of 1988, Pratt & Whitney (P&W), a Division of United Technologies
Corporation (UTC), has been involved in the development for the use of rapid prototyping
technologies that use a "layer-by-Iayer" building approach. Based on over 4 1/2 years
experience with Stereolithography, this paper will address three aspects of our experience
including: Implementation, Current Operations, and Future Plans | null | null | null | null | null | null |
['Zhang, Haiou', 'Li, Runsheng', 'Wang, Rui', 'Fu, Youheng', 'Wang, Xiangping', 'Wang, Guilan', 'Tang, Shangyong'] | 2021-11-04T18:40:33Z | 2021-11-04T18:40:33Z | 2017 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90000', 'http://dx.doi.org/10.26153/16921'] | eng | 2017 International Solid Freeform Fabrication Symposium | Open | ['casting-forging-milling composite', 'CFMC', 'additive manufacturing technology', 'additive manufacturing'] | Casting - Forging - Milling Composite Additive Manufacturing Thechnology | Conference paper | https://repositories.lib.utexas.edu//bitstreams/cca03cb7-d3a9-4f78-9c51-c7ac51d5212f/download | University of Texas at Austin | The current metal additive manufacturing has some drawbacks, such as poor performance in producing
forgings, low accuracy and efficiency, and high cost. This paper proposes a new technology called casting-forging-milling composite (CFMC) additive manufacturing, which uses the efficient and cheap arc as the heat
source. Synchronous arc welding and continuous semi-solid in-situ forging is achieved with micro-roller.
Milling is incorporated into this process to remove defects and complete the part. Workpieces with equiaxed
fine-grained microstructure and better performance than forgings have been obtained using CFMC. Testing
shows that the mechanical performance exceeds the standards for forgings and most indicators are above the
average levels. Trial products include titanium alloy aeronautical parts, a stainless steel propeller, and an aero-engine transition section which has passed the European standard x-ray inspection and test. The streamlined and
low-cost manufacturing process achieved by using metal wire, integrated equipment and low pressure makes
CFMC a green manufacturing model. | null | null | null | null | null | null |
['Gopal, Arjun', 'Parihar, Gaurav', 'Holt, McKay', 'Stinson, Tanner', 'Sharma, Manasvi', 'Bhate, Dhruv'] | 2021-11-30T19:44:25Z | 2021-11-30T19:44:25Z | 2019 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90525', 'http://dx.doi.org/10.26153/tsw/17444'] | eng | 2019 International Solid Freeform Fabrication Symposium | Open | ['selective laser sintering', 'cellular optimization', 'topology optimization', 'beams', 'bending', 'design for additive manufacturing'] | Cellular and Topology Optimization of Beams under Bending: An Experimental Study | Conference paper | https://repositories.lib.utexas.edu//bitstreams/f48d6317-c69d-4629-80a0-3c2ddf8bc43b/download | University of Texas at Austin | Design for Additive Manufacturing (AM) includes concepts such as cellular materials and
topology optimization that combine the capabilities of advanced computational design with those
of AM technologies that can realize them. There is however, limited experimental study of the
relative benefits of these different approaches to design. This paper examines these two different
approaches, specifically in the context of maximizing the flexural rigidity of a beam under
bending, while minimizing its mass. A total of 23 beams were designed using commercially
available cellular design, and topology optimization software. The Selective Laser Sintering (SLS)
process was used to manufacture these beams with Nylon 12, which were then tested per ASTM
D790 three-point bend test standards. The effect of varying the size and shape of cells on the
flexural rigidity was studied using 15 different cellular designs. These results were then compared
to six different topology optimized beam designs, as well as three solid and hollow baseline beams.
These preliminary findings suggest that topology optimized shapes underperform their cellular
counterparts with regard to specific stiffness, and that stochastic cellular shapes deserve deeper
study. | null | null | null | null | null | null |
['Engelbrecht, Sarah', 'Folgar, Luis', 'Rosen, David W.', 'Schulberger, Gary', 'Williams, Jim'] | 2021-09-29T20:27:37Z | 2021-09-29T20:27:37Z | 2009-09 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88215', 'http://dx.doi.org/10.26153/tsw/15156'] | eng | 2009 International Solid Freeform Fabrication Symposium | Open | ['cellular materials', 'conformal lattice structures', 'selective laser sintering', 'additive manufacturing'] | Cellular Structures for Optimal Performance | Conference paper | https://repositories.lib.utexas.edu//bitstreams/99019ca1-29b7-4e85-988f-fd861b3de816/download | University of Texas at Austin | Cellular material structures, such as honeycombs and lattice structures, enable
unprecedented stiffness and strength characteristics, for a given weight. New design and CAD
technologies to construct cellular materials are presented in this paper. Such materials have very
complex geometries, hence the need for additive manufacturing processes to produce them. A
series of experiments was performed to build and test parts fabricated using Selective Laser
Sintering. Variations in mechanical properties were quantified and related to processing
conditions. Examples help illustrate the variety of applications of cellular materials in the
aerospace, automotive, motorsports, energy, electronics, and related industries. A software tool
is being developed to enable users to design and construct parts with cellular structures. | null | null | null | null | null | null |
['Yang, Li', 'Miyanaji, Hadi'] | 2021-11-02T19:19:39Z | 2021-11-02T19:19:39Z | 2017 | Mechanical Engineering | null | https://hdl.handle.net/2152/89871 | eng | 2017 International Solid Freeform Fabrication Symposium | Open | ['ceramics', 'additive manufacturing', 'review', 'applications'] | Ceramic Additive Manufacturing: A Review of Current Status and Challenges | Conference paper | https://repositories.lib.utexas.edu//bitstreams/8d950305-2d9b-4830-920f-98e9c6fed90f/download | University of Texas at Austin | In recent years, various additive manufacturing (AM) technologies that are capable of
processing ceramic materials have been demonstrated. On one hand, many of the AM ceramic
technologies have demonstrated geometry freedom capability and broad range of material
flexibility. In some of the ceramic AM processes the part accuracies have also been favorably
demonstrated. On the other hand, when reviewing the requirements of ceramic structures from
applications perspective, there still appears to exist a misalignment between the demonstrated
capability of ceramic AM and the required performance. The lack of critical microstructural
characteristic and performance evaluation results are likely setting significant barriers for the
broader adoption of ceramic AM, which should be addressed via close collaborations between
academia and industries. | null | null | null | null | null | null |
['Weiss, C.M.', 'Aindow, M.', 'Marcus, H.'] | 2021-09-28T18:15:12Z | 2021-09-28T18:15:12Z | 2009-09 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88142', 'http://dx.doi.org/10.26153/tsw/15083'] | eng | 2009 International Solid Freeform Fabrication Symposium | Open | ['Selective Area Laser Deposition', 'Vapor Infiltration', 'ceramic joints', 'gas phase pulsed laser', 'laser processing'] | Ceramic Joining by Gas Phase Pulsed Laser Processing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/b5081dc2-d65b-4861-bab4-f07d1ee8be90/download | University of Texas at Austin | The method of Selective Area Laser Deposition (SALD) and Vapor Infiltration
(SALDVI) has been successfully used to fabricate small three-dimensional SiC/SiC and
SiC/metal powder parts. Ceramic joints made by this technique have been limited by the
throwing power of the laser resulting in incomplete joint penetration. Studies were performed to
show the effectiveness of a fiber laser, with a wavelength of 1070 nm, for a joining process. The
ability of the laser to penetrate a powder bed was utilized in the joint fabrication. The
combination of powder fill, and deep laser penetration into the powder bed shows potential in the
field of ceramic joining. | null | null | null | null | null | null |
['Tompkins, J.V.', 'Birmingham, B.R.', 'Marcus, H.L.'] | 2018-11-08T15:34:09Z | 2018-11-08T15:34:09Z | 1995 | Mechanical Engineering | doi:10.15781/T2QB9VR4K | http://hdl.handle.net/2152/69889 | eng | 1995 International Solid Freeform Fabrication Symposium | Open | ['Selective beam deposition', 'SALD', 'deposition'] | Ceramic Joining by Selective Beam Deposition | Conference paper | https://repositories.lib.utexas.edu//bitstreams/52d9a51d-7506-4d61-9b1b-20454ce78477/download | null | Current methods ofjoining of ceramic components may compromise the strength, chemical
resistance, or high temperature properties of the resulting ceramic parts. A new method of
joining, Ceramic Joining by Selective Beam Deposition, creates an all-ceramic joint
between two or more ceramic components through selective decomposition of a gas
precursor. An all-ceramic joint not only preserves the valuable properties of the ceramic
materials joined, but may be tailored to match the coefficient of thermal expansion ofthe
original material(s). The added material may be the same as one or both of the joined
Inaterials, or may be a composite material. This preliminary work explores the effect of
scanning speed and precursor pressure on Selective Beam Deposition ofsilicon carbide
using tetramethylsilane. | null | null | null | null | null | null |
['Rafi, Abid Hasan', 'Lakusta, Marharyta', 'Anthony, Vincenzo', 'Basler, Grace', 'Grier, Sophie', 'Moeller, Lauren', 'Lipke, David', 'Watts, Jeremy Lee', 'Hilmas, Greg', 'Leu, Ming C'] | 2023-01-20T14:11:45Z | 2023-01-20T14:11:45Z | 2022 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/117256', 'http://dx.doi.org/10.26153/tsw/44137'] | eng | 2022 International Solid Freeform Fabrication Symposium | Open | ['Additive Manufacturing', 'Ceramic On-Demand Extrusion', 'High-temperature Ceramic', 'Compact Heat Exchanger', 'Microchannel', 'Paste Extrusion'] | Ceramic On-Demand Extrusion of ZrB2-SiC Microchannels for Ultra High-Temperature Compact Heat Exchanger | Conference paper | https://repositories.lib.utexas.edu//bitstreams/ea8ebb4b-0c06-44c6-9e84-7f6f0f65c983/download | null | Ceramic On-Demand Extrusion (CODE) is a paste extrusion based additive manufacturing
process that has been developed for the fabrication of dense ceramic components. This paper
presents a study of using the CODE process to build microchannels with ZrB2-SiC aqueous paste
for the fabrication of an ultra-high-temperature compact heat exchanger (CHE). The aqueous paste
is developed from ZrB2 and SiC (70/30 vol%) powders to possess properties suitable for the
extrusion process. The performance and properties of the microchannels are tested for use in the
CHE, which features a large heat transfer area to volume ratio and has potential applications in
aero-engines, microturbines, etc., as well as high-efficiency power generation systems. | null | null | null | null | null | null |
['Griffith, Michelle L.', 'Chu, Tien.Min', 'Wagner, Warren', 'Halloran, John W.'] | 2018-10-03T19:55:01Z | 2018-10-03T19:55:01Z | 1995 | Mechanical Engineering | doi:10.15781/T20K26W76 | http://hdl.handle.net/2152/68685 | eng | 1995 International Solid Freeform Fabrication Symposium | Open | ['alumina', 'SLA', 'custom-made hydroxyapatite ceramic implants'] | Ceramic Stereolithography for Investment Casting and Biomedical Applications | Conference paper | https://repositories.lib.utexas.edu//bitstreams/5c213bad-7ea0-465c-bd6e-7a5bf32c93d2/download | null | Ceramic green bodies can be created using stereolithography methods by using an
ultraviolet curable suspension of ceramic powders in place of the usual resin -a "ceramic resin".
Weare developing ceramic resins from hydryoxyapatite ceramics, to enable custom made ceramic
implants by SLA, and from silica and alumina, to enable metal casting molds by SLA. We
demonstrate SLA ofsilica, a model refractory for metal casting molds, and SLA of alumina, which
present the rheological behavior and UV curing properties of several "ceramic resins", and discuss
silica parts made on an SLA-250. | null | null | null | null | null | null |
['Vail, N.K.', 'Barlow, J.W.'] | 2018-04-19T17:17:39Z | 2018-04-19T17:17:39Z | 1992 | Mechanical Engineering | doi:10.15781/T2TB0ZC2F | http://hdl.handle.net/2152/64387 | eng | 1992 International Solid Freeform Fabrication Symposium | Open | ['Department of Chemical Engineering', 'SLS', 'Selective Laser Sintering', 'high-temperature'] | Ceramic Structures by Selective Laser Sintering of Microencapsulated, Finely Divided Ceramic Materials | Conference paper | https://repositories.lib.utexas.edu//bitstreams/817d8b43-60ab-4939-a2e5-78888678e5ce/download | null | The feasibility of producing ceramic green parts by Selective Laser Sintering
from microencapsulated, finely divide ceramic powders has been reported in
an earlier paper. Post-processing of a silica/zirconium orthosilicate system
and an alumina system, both utilizing a polymer binder in the form of a
coating, are discussed in this paper. Ceramic green parts require postprocessing
to remove the intermediate polymer binder and to impart strength
properties to the ceramic bodies. In this paper, the use of ceramic cements
and high temperature firing to realize strengths will be discussed. The effects
of cement concentration and controlled drying rates on the strengths and
dimensional accuracy of the ceramic bodies are also discussed. | null | null | null | null | null | null |
['Cheverton, Mark', 'Singh, Prabhjot', 'Smith, Scott', 'Chan, Kwok Pong'] | 2021-10-06T22:28:12Z | 2021-10-06T22:28:12Z | 2012 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88459', 'http://dx.doi.org/10.26153/tsw/15396'] | eng | 2012 International Solid Freeform Fabrication Symposium | Open | ['additive manufacturing', 'ceramic polymers', 'ultrasound transducers', 'piezoelectric'] | Ceramic-Polymer Additive Manufacturing System for Ultrasound Transducers | Conference paper | https://repositories.lib.utexas.edu//bitstreams/a86d0a19-7fb0-447d-9dff-58ec4007c69e/download | University of Texas at Austin | A modified multi-layer lithography process is used to additively manufacture highresolution netshape ceramic structures by photopolymerizing a ceramic-polymer slurry using
structured light patterns. This paper will discuss the development of a low-cost, high speed
manufacturing process method for the fabrication of piezoelectric ceramic transducer elements in
the 1-25 MHz frequency range. The key considerations in the development of the process
including the selection and optimization of slurry materials for the deposition of PZT 5H
materials, optical exposure parameters, debinding/sintering profiles, process monitoring, and
post manufacturing processing. Ongoing work includes improvements to the materials
properties, improved throughput and geometric fidelity. | null | null | null | null | null | null |
['Khoshnevis, Behrokh', 'Zhang, Jing', 'Fateri, Miranda', 'Xiao, Zichen'] | 2021-10-12T20:50:52Z | 2021-10-12T20:50:52Z | 2014 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88738', 'http://dx.doi.org/10.26153/tsw/15672'] | eng | 2014 International Solid Freeform Fabrication Symposium | Open | ['Additive Manufacturing', 'Selective Inhibition Sintering', 'sintering inhibitor', 'ceramics 3D printing'] | Ceramics 3D Printing by Selective Inhibition Sintering | Conference paper | https://repositories.lib.utexas.edu//bitstreams/c05e41b3-8a2e-46d8-aaf1-c0abbd4ffbad/download | University of Texas at Austin | Selective Inhibition Sintering (SIS) has been proven effective in producing polymeric and
metallic parts. Due to the low cost and high quality of SIS printing, the impact of SIS printing in
the 3D printing industry could be disruptive. The potential of SIS is further extended to ceramics,
an important but hard to print material, by the same mechanism of creating an easy-to-break
sacrificial mold. Due to the high sintering temperature of ceramics, fluid based inhibitors
delivered by inkjet printing tend to not be effective in SIS for ceramics. Accordingly, the new
concept of inhibition by dry powder delivery is implemented. Preliminary experiments have
shown the feasibility and ease of printing of simple ceramic parts. Additional experiments are
underway to increase the possible part complexity and accuracy, and to optimize the sintering process. | null | null | null | null | null | null |
['Taylor, Robert M.', 'Manzo, Joe', 'Flansburg, Lori'] | 2021-11-01T20:51:12Z | 2021-11-01T20:51:12Z | 2016 | Mechanical Engineering | null | https://hdl.handle.net/2152/89745 | eng | 2016 International Solid Freeform Fabrication Symposium | Open | ['certification process', 'strategy', 'structural fittings', 'additive manufacturing'] | Certification Strategy for Additively Manufactured Structural Fittings | Conference paper | https://repositories.lib.utexas.edu//bitstreams/517fc9fd-d3b4-49d1-ac88-34d6910613be/download | University of Texas at Austin | While many opportunities exist to leverage additive manufacturing technology for design
improvement, structural component fabrication with additive technologies must
demonstrate reliability and integrity sufficient to satisfy certification authorities in order to
open the door for use on flight vehicles. This certification challenge is formidable given the
large number of process parameters, the magnitude of process variability, and the sensitivity
of mechanical properties to these process variables. Historical precedent in certification of
other materials and processes, such as composites, castings, and welded joints that exhibit
sensitivity to parameters, geometry, and operator skill provides a guide to certification of
additive structures. This paper discusses certification processes for these components and
applies lessons and methods from them to develop a strategy to certify an additively
manufactured structural fitting component. | null | null | null | null | null | null |
['Patel, Sagar', 'Keshavarz, Mohsen', 'Vlasea, Mihaela'] | 2021-12-06T23:12:26Z | 2021-12-06T23:12:26Z | 2021 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90711', 'http://dx.doi.org/10.26153/tsw/17630'] | eng | 2021 International Solid Freeform Fabrication Symposium | Open | ['laser powder bed fusion', 'selective laser melting', 'titanium', 'Ti6242', 'density', 'roughness', 'cracking'] | Challenges during laser Powder Bed Fusion of a Near-Alpha Titanium Alloy - Ti-6242Si | Conference paper | https://repositories.lib.utexas.edu//bitstreams/66e1fd99-2a39-411d-9b3d-cf168888fba7/download | University of Texas at Austin | Ti-6Al-2Sn-4Zr-2Mo-Si (Ti-6242Si) is a near-α phase titanium alloy that has a greater strength up to 565
°C compared to the workhorse Ti-6Al-4V alloy with a typical service temperature of up to 400 °C. While there
is a wealth of literature to help understand the laser powder bed fusion (LPBF) of Ti-6Al-4V, only a few
research articles about LPBF of Ti-6242Si are available in the open literature. In this work, LPBF processing
diagrams and temperature prediction models were used to investigate the impact of process parameters such as
laser power, scan speed, and beam spot radius on macroscale characteristics of the builds such as density and
surface roughness. The use of processing diagrams allowed for exploration of density ranges between
99.55-99.98 %, and surface roughness, Sa, ranges between 8-16 μm in Ti-6242Si processed by LPBF.
Cracking in Ti-6242Si manufactured by LPBF is reported for the first time. Cracking during LPBF of Ti-6242Si
was observed to strongly depend upon the predicted melting mode (conduction, transition, and keyhole) for a
given set of LPBF process parameters. | null | null | null | null | null | null |
['Bekker, Anne C.M.', 'Verlinden, Jouke C.', 'Galimberti, Giorgia'] | 2021-10-26T19:23:01Z | 2021-10-26T19:23:01Z | 2016 | Mechanical Engineering | null | https://hdl.handle.net/2152/89563 | eng | 2016 International Solid Freeform Fabrication Symposium | Open | ['wire + arc additive manufacturing', 'WAAM', 'sustainability', 'life cycle assessment'] | Challenges in Assessing the Sustainability of Wire + Arc Additive Manufacturing for Large Structures | Conference paper | https://repositories.lib.utexas.edu//bitstreams/b00c74bc-6b9a-48b6-a978-7d56f4ed8075/download | University of Texas at Austin | Additive manufacturing is known as a disruptive technology, in enabling freedom in shape and on-demand
production with little human intervention. At present, large-scale digital manufacturing means are being
developed, such as Wire & Arc Additive Manufacturing (WAAM). These could be beneficial in aerospace,
automotive and construction industries. However, while the technology is rapidly developing, little is known on
the sustainability aspects. This article explores how such environmental effects could be assessed for a novel
technology, and the production of large-scale products by means of a Life Cycle Assessment (LCA). Forerunning
results show possible gains in material usage when compared to traditional manufacturing technologies, and in
power consumption when compared to different additive manufacturing technologies. Future research will focus
benchmarking WAAM against alternative manufacturing techniques, including green sand casting and CNC
milling. | null | null | null | null | null | null |
['Nycz, Andrzej', 'Noakes, Mark W.', 'Richardson, Bradley', 'Messing, Andrew', 'Post, Brian', 'Paul, Jonathan', 'Flamm, Jason', 'Love, Lonnie'] | 2021-11-04T18:49:37Z | 2021-11-04T18:49:37Z | 2017 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90002', 'http://dx.doi.org/10.26153/16923'] | eng | 2017 International Solid Freeform Fabrication Symposium | Open | ['large-scale metal parts', 'additive manufacturing excavator', 'AME', 'case study', 'challenges'] | Challenges in Making Complex Metal Large-Scale Parts for Additive Manufacturing: A Case Study Based on the Additive Manufacturing Excavator | Conference paper | https://repositories.lib.utexas.edu//bitstreams/e6aed5a2-9e44-4d90-92fe-404860a0d897/download | University of Texas at Austin | The Additive Manufacturing Excavator (AME) contained several key components that
were 3D printed at The Manufacturing Demonstration Facility (MDF) of Oak Ridge National
Laboratory (ORNL); it was presented at and performed a live demonstration for the CONEXPO
2017 exhibition in Las Vegas, Nevada in March of 2017. This paper presents challenges in building
functional, large-scale metal parts based on a case study of the excavator. The excavator’s metal
arm was 3D printed using a modified Wolf Robotics automated metal inert gas (MIG) welding
cell. Tasks included designing a new type of slicer for the metal additive manufacturing (AM)
process, integrating the slicing software with the Wolf Robotics system, developing the deposition
process, characterizing geometric features and material properties, managing heat, designing
mechanical components for metal AM, and developing a machining approach to achieve the final
part. Two fully functional excavator arms were printed and machined. Integrated hydraulics
passageways that also served as structural stiffeners were included in the build for demonstration
purposes. As a direct result of this project, Wolf Robotics is now working towards a commercially
available large-scale metal AM system. | null | null | null | null | null | null |
['Chesser, Phillip', 'Post, Brian K.', 'Lind, Randall', 'Lloyd, Peter', 'Love, Lonnie J.'] | 2021-11-04T14:46:58Z | 2021-11-04T14:46:58Z | 2017 | Mechanical Engineering | null | https://hdl.handle.net/2152/89974 | eng | 2017 International Solid Freeform Fabrication Symposium | Open | ['changing print resolution', 'nozzle diameter', 'selectable nozzle', 'BAAM', 'big area additive manufacturing'] | Changing Print Resolution on BAAM via Selectable Nozzles | Conference paper | https://repositories.lib.utexas.edu//bitstreams/a00b5470-718a-422d-9b09-539153b952d5/download | University of Texas at Austin | Big Area Additive Manufacturing (BAAM) is an additive manufacturing (AM) technique
that rapidly deposits polymer to fabricate large components. However, the increase in deposition
rates leads to a decrease in resolution and a consequent decline in part surface finish. A novel
technique has been developed where the nozzle diameter can be changed mid-print using a poppet
nozzle selector. With this technique, a course resolution can be employed to rapidly fabricate the
interior of a part, while a fine resolution can be used on the surface. This allows for improved
surface quality and resolution without significantly increasing print time. This work will explain
the development of the selectable nozzle and integration with the BAAM system to produce
selective high-resolution surfaces on parts. | null | null | null | null | null | null |
['Cunningham, C.R.', 'Wang, J.', 'Dhokia, V.', 'Shrokani, A.', 'Newman, S.T.'] | 2021-11-17T23:56:35Z | 2021-11-17T23:56:35Z | 2019 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90361', 'http://dx.doi.org/10.26153/tsw/17282'] | eng | 2019 International Solid Freeform Fabrication Symposium | Open | ['wire arc additive manufacturing', 'additive manufacturing', 'interpass temperature', '316LSi', 'directed energy deposition'] | Characterisation of Austenitic 316 LSi Stainless Steel Produced by Wire Arc Additive Manufacturing with Interlayer Cooling | Conference paper | https://repositories.lib.utexas.edu//bitstreams/2eb5a961-e518-4f0b-8ebf-68e4120e86e4/download | University of Texas at Austin | Wire arc additive manufacturing (WAAM) expands the possibilities of cost effectively producing
large-scale, complex metal objects at high deposition rates. Austenitic stainless steel is a
commonly used material and has many applications in the marine and nuclear industry due to its
high toughness and corrosion resistance. Processes parameters such as heat input and interpass
temperature can greatly affect the materials properties, part functionality and the economics of
WAAM production. However, the effect of these process parameters is not well understood for
WAAM of 316LSi. In this research, the effects of the interpass temperature and heat input process
parameters on WAAM of austenitic AISI 316LSi stainless steel are experimentally analysed and
evaluated. It was found that the heat input and interpass temperature influences the
cellular/dendritic morphology and the formation of macro-scale grains within the microstructure.
Additionally, use of higher heat input, resulted in a 28.7% improvement in average Young’s
modulus compared to lower heat input, although this remained lower than provided by wrought
annealed material. | null | null | null | null | null | null |
['Hoye, N.P.', 'Appel, E.C.', 'Cuiuri, D.', 'Li, H.'] | 2021-10-07T14:55:57Z | 2021-10-07T14:55:57Z | 2012 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88470', 'http://dx.doi.org/10.26153/tsw/15407'] | eng | 2012 International Solid Freeform Fabrication Symposium | Open | ['metal deposition', 'additive manufacturing', 'gas tungsten arc', 'cold wire', 'aerospace'] | Characterisation of Metal Deposition During Additive Manufacturing of Ti-6Al-4V by Arc-Wire Methods | Conference paper | https://repositories.lib.utexas.edu//bitstreams/5410e0e9-c23e-4a5b-be29-64ad06739eb4/download | University of Texas at Austin | This study considers the use of the gas tungsten arc (GTA) welding process in
conjunction with ‘cold’ wire addition to give layer-wise build-up of thin walled structures,
simulating those commonly found in aerospace applications, which may in the future be
manufactured by additive means. Taguchi DOE and multiple regression analysis methods have
been applied to quantitatively establish relationships between common process parameters
including arc length, arc current, travel speed and wire feed speed and resulting weld bead
geometries and actual metal deposition rates. Mathematical expressions for build-up height,
thickness and surface roughness are presented and evaluated against experimental data, with
observations related to physical phenomena. | null | null | null | null | null | null |
['Tang, H. H.', 'Yen, H. c.', 'Chiu, M. L.', 'Jou, J. H.'] | 2020-03-11T15:08:10Z | 2020-03-11T15:08:10Z | 9/10/08 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/80246', 'http://dx.doi.org/10.26153/tsw/7265'] | eng | 2008 International Solid Freeform Fabrication Symposium | Open | Ceramic Laser Fusion | The Characteristics and Applications of Ceramic Laser Fusion and Ceramic Laser Sintering | Conference paper | https://repositories.lib.utexas.edu//bitstreams/89c9af32-4633-4198-9daf-6a86f88dcdbc/download | null | The aim of present study is to investigate the possible application of the ceramic parts
which are fabricated with the process of Ceramic Laser Fusion or Ceramic Laser Sintering.
The experimental results reveal: (1) CLF can lead to a reduction in the porosity of the
ceramic part but also can induce micro-cracks. Therefore, this process cannot produce a part
with the required strength by a post-process of infiltration; (2) CLS is capable of fabricating a
ceramic part with high porosity. By adjusting the slurry formulation and varying the scanning
energy, the open porosity can be over 90vol% of the total porosity. After a post-process of
infiltration, the density can be increased to 95%; therefore, CLS can apply to produce a part
with high strength. Because the high open porosity leads to a good permeability, the process
of CLS is suitable for the fabrication of ceramic shell mold. | null | null | null | null | null | null |
['Masuo, Christopher', 'Nycz, Anddrzej', 'Nycz, Andrzej', 'Noakes, Mark W.', 'Love, Lonnie J.'] | 2021-11-09T16:36:49Z | 2021-11-09T16:36:49Z | 2018 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90108', 'http://dx.doi.org/10.26153/tsw/17029'] | eng | 2018 International Solid Freeform Fabrication Symposium | Open | ['build characteristics', 'geometric features', 'wire-arc additive manufacturing', 'WAAM'] | Characterization and Analysis of Geometric Features for the Wire-Arc Additive Process | Conference paper | https://repositories.lib.utexas.edu//bitstreams/67403813-7581-4c19-b8f3-ad613e858515/download | University of Texas at Austin | The wire-arc additive manufacturing (AM) process expands the possibilities of effectively
producing large-scale, complex metal objects through high deposition rates at low costs. However,
this process is prone to irregularities in geometric features that occur from improper thermal
conditions and build parameters that cause uneven build heights. This paper discusses a method to
obtain consistent build characteristics and near net shape geometric features for the wire-arc AM
process. Process parameters are established for each material printed to ensure characterization of
layer build height and even flow in the interior of parts. Various sections of the build including
perimeter, infill, and various wall thicknesses require different strategies to correctly build the part.
Open-loop build geometry is still not sufficient to build a part to near net shape of the original
model. Average layer height is determined and used with adaptive height control to print the
correct, modeled height. | null | null | null | null | null | null |
Srinivasan, Rohit K. | 2021-10-28T22:06:34Z | 2021-10-28T22:06:34Z | 2016 | Mechanical Engineering | null | https://hdl.handle.net/2152/89713 | eng | 2016 International Solid Freeform Fabrication Symposium | Open | ['3D printing', 'sprockets', 'robotics', 'plastic sprockets', 'Chap Research'] | Characterization and Testing of 3D Printed Sprockets | Conference paper | https://repositories.lib.utexas.edu//bitstreams/fed8a4f1-8f64-4a70-abca-b0c0e3321427/download | University of Texas at Austin | Although arguably only 30 years old, 3D printing is already having a tremendous impact upon a
broad spectrum of industries, from medical products to consumer goods and nearly every industry in
between. The primary driver for growth has been the ability to rapidly prototype components at very
low cost. However, as 3D printing technology has matured, industry participants are experimenting
with printing components for production and long-term use as opposed to just prototypes.
Chap Research has created a web-based application used to 3D print a “sprocket” – a toothed wheel
used in chain-driven systems. This paper details our study to determine the applicability of these plastic
3D printed sprockets in production and for long-term use within certain robotics applications, an area
traditionally dominated by metal (aluminum) sprockets.
The study varied a range of design parameters and evaluated whether plastic (PLA) 3D printed
sprockets could withstand the torsional stresses and fatigue failure modes present in robotics
applications (specifically for FIRST competition robots). This paper also describes two custom test
rigs that were built, one to characterize torsional stress and the other for fatigue stress analysis.
Our study indicated that, for our target application, FIRST robotics competitions, 3D printed
sprockets were quite sufficient in production and for long-term use. Layer height and infill settings for
the 3D prints had the largest impact on the performance of these sprockets. While this is not a study to
comprehensively compare performance of 3D printed sprockets to their aluminum counterparts, the big
surprise was that 3D printed sprockets performed even better than metal sprockets for fatigue stress
modes of failure. Using these results, this study also makes some recommendations on infill and layer
height settings for achieving the desired performance for FIRST robotics applications.
The study also showed the relationship between the load applied to a 3D printed sprocket and the
number of cycles of continuous operation before a fatigue load related failure occurred and makes a
conjecture on a range of load for “infinite life” of operation.
Future extensions of this study may focus on additional fatigue loading tests, expanding to broader
sets of load and printer conditions, further optimization of build parameters, varying printing materials,
and different 3D printing technologies such as SLS. | null | null | null | null | null | null |
['Taminger, Karen M.B.', 'Hafley, Robert A.'] | 2019-10-24T18:29:28Z | 2019-10-24T18:29:28Z | 2002 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/77421', 'http://dx.doi.org/10.26153/tsw/4510'] | eng | 2002 International Solid Freeform Fabrication Symposium | Open | Fabrication | Characterization of 2219 Aluminum Produced by Electron Beam Freeform Fabrication | Conference paper | https://repositories.lib.utexas.edu//bitstreams/ceb76f83-7724-4aaa-a5d9-6355f853b1e9/download | null | Researchers at NASA Langley Research Center are developing a new electron beam
freeform fabrication (EB F3
) technique to fabricate metal parts. This process introduces metal
wire into a molten pool created by a focused electron beam. Potential aerospace applications for
this technology include ground-based fabrication of airframe structures and on-orbit construction
and repair of space components and structures. Processing windows for reliably producing high
quality 2219 aluminum parts using the EB F3
technique are being defined. The effects of
translation speed, wire feed rate, and beam power on the resulting microstructures and
mechanical properties are explored. Tensile properties (ultimate tensile strength, yield strength,
and elongation) show little effect over the range of processing conditions tested. Basic
processing-microstructure-property correlations are drawn for the EB F3
process. | null | null | null | null | null | null |
['Mao, Q.', 'Coutris, N.', 'Fadel, G.'] | 2021-10-12T22:53:01Z | 2021-10-12T22:53:01Z | 2014 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88763', 'http://dx.doi.org/10.26153/tsw/15697'] | eng | 2014 International Solid Freeform Fabrication Symposium | Open | ['ultrasonic additive manufacturing', 'acoustic softening', 'deformation', 'aluminum 6061'] | Characterization of Acoustic Softening of Aluminum 6061 Within a Plasticity Framework | Conference paper | https://repositories.lib.utexas.edu//bitstreams/489ef854-6a7c-4986-a9ff-11a7cb5942f1/download | University of Texas at Austin | Ultrasonic additive manufacturing (UAM) is a rapid prototyping technology that features
a metal joining process through ultrasonic welding. The bonding mechanisms and mechanics of
UAM have been investigated for decades. Meanwhile, the plastic deformations of metals were
extensively studied by many researchers for their significant roles in bond formation. However,
most of these research efforts considered solely the surface frictional effects on plastic
deformation whereas the volumetric effects of ultrasound were rarely considered. This paper
investigates the effects of ultrasound on deformation of Aluminum 6061 through experimental
studies and highlights the volumetric effects of ultrasound, i.e. the “acoustic softening”: a stress
reduction on the stress-strain relation of Aluminum 6061 upon application of ultrasounds. Based
on observations obtained from a designed experimental setup, a phenomenological model is
proposed to characterize the acoustic softening effects in terms of the ultrasonic intensities.
Additionally, by modifying Hockett’s plasticity model, a plasticity frame work is established to
characterize the deformation of Aluminum 6061 in UAM. The acoustic softening model is then
incorporated into the plasticity framework. The complete model is then validated by comparing
its predictions with experimental measurements. | null | null | null | null | null | null |
['Brown, Ben', 'Everhart, Wes', 'Dinardo, Joe'] | 2021-10-20T20:26:29Z | 2021-10-20T20:26:29Z | 2015 | Mechanical Engineering | null | https://hdl.handle.net/2152/89354 | eng | 2015 International Solid Freeform Fabrication Symposium | Open | ['powder bed additive manufacturing', 'bulk wall', 'thin wall', 'mechanical response', 'metals', 'process parameters'] | Characterization of Bulk to Thin Wall Mechanical Response Transition in Powder Bed AM | Conference paper | https://repositories.lib.utexas.edu//bitstreams/41c4e872-7c26-482c-b544-36ef7fabd5d0/download | University of Texas at Austin | In the development of powder bed AM process parameters, the characterization of
mechanical properties is generally performed through relatively large mechanical test
samples that represent a bulk response. This provides an accurate representation of
mechanical properties for equivalently sized or larger parts. However as feature size is
reduced, mechanical properties transition from a standard bulk response to a thin wall
response where lower power border scans and surface roughness have a larger effect. This
study identifies this threshold between bulk and thin wall for 304L SS on the Selective
Laser Melting (SLM) platform and Ti-6Al-4V on the Electron Beam Melting (EBM) platform. A possible method for improving those properties and shifting the transition from
bulk to thin wall response to smaller wall thicknesses was investigated. Mechanical testing and fractography was performed on samples to characterize the effect of wall thickness. | null | null | null | null | null | null |
['Whiting, J.', 'Fox, J.'] | 2021-10-28T14:48:14Z | 2021-10-28T14:48:14Z | 2016 | Mechanical Engineering | null | https://hdl.handle.net/2152/89655 | eng | 2016 International Solid Freeform Fabrication Symposium | Open | ['powder bed fusion', 'particle size distribution', 'powder spreading'] | Characterization of Feedstock in the Powder Bed Fusion Process: Sources of Variation in Particle Size Distribution and the Factors that Influence Them | Conference paper | https://repositories.lib.utexas.edu//bitstreams/d55943cb-27be-43aa-a9ed-975481ae13ee/download | University of Texas at Austin | Substantial efforts have been placed on characterizing and modeling additive manufacturing
processes. The wide scope of work already done has focused on the effects of process parameters
such as laser power, hatch spacing, scan speed and strategy, and layer thickness on the final part’s
properties. However, the characteristics of the actual powder should also be considered. The
particles’ size, morphology, roughness, and chemical composition will affect the final part
properties including surface texture, density, tensile strength, and hardness. This paper will share
some of the measurement methods used at the National Institute of Standards and Technology
(NIST) to better understand metal powder for additive manufacturing. These include the
striation/separation in transportation and handling, sampling procedures, and the actual spreading
of powder in the laser powder bed fusion process. Results are presented that illustrate variations
in the particle size distribution as a function of location on the build platform, substrate/part surface
condition, and vertical position. | null | null | null | null | null | null |
['Sutton, Austin T.', 'Kriewall, Caitlin S.', 'Leu, Ming C.', 'Newkirk, Joseph W.'] | 2021-11-02T14:58:05Z | 2021-11-02T14:58:05Z | 2017 | Mechanical Engineering | null | https://hdl.handle.net/2152/89819 | eng | 2017 International Solid Freeform Fabrication Symposium | Open | ['heat-affected powder', '304L', 'stainless steel', 'selective laser melting', 'characterization'] | Characterization of Heat-Affected Powder Generated During the Selective Laser Melting of 304L Stainless Steel Powder | Conference paper | https://repositories.lib.utexas.edu//bitstreams/679bbd0c-f68f-4941-908b-8d800e2aafa2/download | University of Texas at Austin | The selective laser melting (SLM) process is an Additive Manufacturing (AM) technique that uses
a laser to fuse successive layers of powder into near fully dense components. Due to the large
energy input from the laser during processing, vaporization and instabilities in the melt pool occur
causing the formation of condensate and laser spatter, collectively known as heat-affected powder.
Since heat-affected powder settles into the powder bed, the properties of the unconsolidated
powder may be altered compromising its reusability. In this study, characterization of 304L heat-affected powder was performed through particle size distribution measurements, x-ray diffraction,
metallography, energy-dispersive spectroscopy mapping, and visualization of grain structure with
the aid of a focused-ion beam. The results show morphological, microstructural, and surface
chemistry differences between the starting powder and heat-affected powder formed during
processing which aid in the understanding of laser spatter and condensate that form in the SLM
process. | null | null | null | null | null | null |
['Cormier, Denis', 'Harrysson, Ola', 'West, Harvey'] | 2019-11-21T18:27:13Z | 2019-11-21T18:27:13Z | 2003 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/78559', 'http://dx.doi.org/10.26153/tsw/5615'] | eng | 2003 International Solid Freeform Fabrication Symposium | Open | Beam Melting | Characterization of High Alloy Steel Produced Via Electron Beam Melting | Conference paper | https://repositories.lib.utexas.edu//bitstreams/15e4089e-8303-4fbc-875d-f948b8746f03/download | null | Electron Beam Melting (EBM) is a direct-to-metal freeform fabrication technique in
which a 4 kW electron beam is used to melt metal powder in a layer-wise fashion. As this
process is relatively new, there have not yet been any independently published studies of
the high alloy steel microstructural properties. This paper describes the EBM process and
presents results of microstructural analyses on H13 tool steel processed via EBM. | null | null | null | null | null | null |
['Weaver, Jason', 'Jones, Jason'] | 2021-11-09T15:29:35Z | 2021-11-09T15:29:35Z | 2018 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90095', 'http://dx.doi.org/10.26153/tsw/17016'] | eng | 2018 International Solid Freeform Fabrication Symposium | Open | ['computer numerical controlled', 'CNC milling machine', 'high deposition polymer extrusion', 'hybrid manufacturing'] | Characterization of High-Deposition Polymer Extrusion in Hybrid Manufacturing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/2f22aeb5-cc8d-4997-bf11-557a2bbbe0b3/download | University of Texas at Austin | Hybrid manufacturing processes that include additive and subtractive operations have
unlocked many of the design limitations that were not previously available. Additive processes
allow increased design flexibility, customization, and complexity. Subtractive processes enable
higher production speeds and improved accuracy and surface finish. This paper describes a hybrid
system that combines a computer numerically controlled (CNC) milling machine with a high
deposition rate polymer extruder to create artifacts using hybrid additive/subtractive processes.
Future research plans are described, including possible applications for this system in
multimaterial and multi-process manufacturing. | null | null | null | null | null | null |
['Karnati, Sreekar', 'Khiabani, Atoosa', 'Flood, Aaron', 'Liou, Frank', 'Newkirk, Joseph W.'] | 2021-11-11T14:59:27Z | 2021-11-11T14:59:27Z | 2018 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90210', 'http://dx.doi.org/10.26153/tsw/17131'] | eng | 2018 International Solid Freeform Fabrication Symposium | Open | ['impact toughness', '304L', 'stainless steel', 'laser powder bed fusion', 'additive manufacturing'] | Characterization of Impact Toughness of 304L Stainless Steel Fabricated Through Laser Powder Bed Fusion Process | Conference paper | https://repositories.lib.utexas.edu//bitstreams/854efced-253b-4e38-aba3-c6cbab7927c4/download | University of Texas at Austin | In this research, the impact toughness of powder bed based additively manufactured 304L
stainless steel was investigated. Charpy specimens were built in vertical, horizontal and inclined
(45°) orientations to investigate the variation in toughness with build direction. These specimens
were tested in as-built and machined conditions. A significant difference in toughness was
observed with varying build directions. The lowest toughness values were recorded when the notch
was oriented in line with the interlayer boundary. The highest toughness was recorded when the
notch was perpendicular to the interlayer boundary. A significant scatter in toughness values was
also observed. The variation and distribution among the toughness values were modeled by
performing 3-parameter Weibull fits. The performance and variation of the additively
manufactured 304L were also compared with the toughness values of wrought 304 stainless. The
additively manufactured material was observed to be significantly less tough and more variant in
comparison to wrought material. | null | null | null | null | null | null |
['Perez, K. Blake', 'Williams, Christopher B.'] | 2021-10-12T20:11:33Z | 2021-10-12T20:11:33Z | 2014 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88730', 'http://dx.doi.org/10.26153/tsw/15664'] | eng | 2014 International Solid Freeform Fabrication Symposium | Open | ['extrusion-based direct write', 'PolyJet', 'material jetting', 'in-situ', 'conductive traces', 'Direct Write', 'Additive Manufacturing'] | Characterization of In-Situ Conductive Paste Extrusion on PolyJet Substrates | Conference paper | https://repositories.lib.utexas.edu//bitstreams/2308841a-a6e9-44b1-9c42-88257d5ede45/download | University of Texas at Austin | The integration of Direct Write technologies into Additive Manufacturing system enables the
in-situ deposition of conductive traces during part printing, and thus the creation of parts with
embedded electronics. In this paper, the authors detail their research of integrating an
extrusion-based direct write system into a PolyJet material jetting system to create multimaterial products with structurally integrated, functional electronics. An investigation of the
dispensing (e.g. orifice diameter, dispense pressure, and toolhead speed), drying (e.g., time and
temperature), and substrate parameters (e.g., VeroWhitePlus and TangoBlackPlus) on the
geometry of the deposited trace is presented. Additionally, the adhesive compatibility of the
conductive material on both rigid and elastomeric PolyJet substrate surfaces is investigated by
measuring wet and dry contact angles. | null | null | null | null | null | null |
['Pappas, John M.', 'Dong, Xiangyang'] | 2021-11-18T02:02:37Z | 2021-11-18T02:02:37Z | 2019 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90406', 'http://dx.doi.org/10.26153/tsw/17327'] | eng | 2019 International Solid Freeform Fabrication Symposium | Open | ['transparent ceramics', 'magnesium aluminate spinel', 'laser direct deposition', 'additive manufacturing'] | Characterization of Laser Direct Deposited Magnesium Aluminate Spinel Ceramics | Conference paper | https://repositories.lib.utexas.edu//bitstreams/73d3fbf4-b26c-4794-8b40-fe24ca96c526/download | University of Texas at Austin | An additive manufacturing (AM) approach, via laser direct deposition, is investigated in printing
transparent magnesium aluminate spinel (MAS) ceramics. Using AM, traditionally difficult or
expensive to manufacture shapes, such as optical lenses, can be rapidly manufactured to near net
shape, reducing time consuming and expensive post processing requirements. The transparency of
MAS ceramics is highly dependent on the microstructure, with porosity and microcracking having
the largest effect on the transparency of fabricated parts. With high localized heat inherent in the
laser deposition process, the microstructure of ceramic parts can be controlled by adjusting
processing parameters. In this study, thin wall MAS structures were fabricated by varying
processing parameters. Processing parameters including laser scan speed and laser power had a
large influence on the part quality. To fabricate transparent magnesium aluminate spinel ceramics
with high mechanical properties, the effects of processing parameters on part porosity, density,
and microstructure were studied. Dense MAS parts were successfully fabricated through the laser
direct deposition process. Low scan speed and high laser power showed the most promising results
in fabricating MAS parts of low porosity. Using a low powder flow rates of 0.58 g/min, a relative
density of nearly 98% was achieved. Directional cooling through the substrate and from the
powder conveying gas led to columnar grain growth at a tilt angle from the build direction. The
primary defects of fabricated MAS ceramics were found to be residual porosity and microcracking,
which negatively affected part transparency and mechanical properties. Typical microcracking
patterns included transverse and longitudinal cracking, with longitudinal cracks being more
prevalent due to the existence of columnar grains and intergranular fracture mode. A preliminary
study demonstrated that a certain degree of transparency was achieved in additively manufactured
MAS ceramic parts via laser direct deposition. | null | null | null | null | null | null |
['Basak, Amrita', 'Das, Suman'] | 2021-11-02T14:11:52Z | 2021-11-02T14:11:52Z | 2017 | Mechanical Engineering | null | https://hdl.handle.net/2152/89809 | eng | 2017 International Solid Freeform Fabrication Symposium | Open | ['nickel-base superally', 'MAR-M247', 'additive manufacturing', 'scanning laser epitaxy', 'SLE', 'microstructure', 'Vickers microhardness', 'residual stress'] | Characterization of MAR-M247 Deposits Fabricated Through Scanning Laser Epitaxy (SLE) | Conference paper | https://repositories.lib.utexas.edu//bitstreams/cd71d8c3-e3c5-4efb-a72b-07d448a131f9/download | University of Texas at Austin | This paper aims to characterize the microhardness and the process-induced residual stress in
nickel-base superalloy MAR-M247 fabricated using a laser-powder bed fusion (LPBF)-based
additive manufacturing (AM) process, scanning laser epitaxy (SLE). The SLE fabricated MAR-M247 samples are investigated using optical microscopy, scanning electron microscopy, x-ray
diffraction, and Vickers microhardness measurements. The results show that the average Vickers
microhardness values do not show any significant variation with changes in SLE processing
parameters. However, the microhardness values are unevenly distributed and show variations
along the build direction and the laser movement direction. Overall the hardness values are within
±2 limits for all the SLE deposited MAR-M247 samples. The effect of heat treatment on the
microhardness and the residual stress is also investigated. The results show that the microhardness
increases and the residual stress decreases after the heat treatment. | This work is sponsored by the
Office of Naval Research through grant N00014-14-1-0658. | null | null | null | null | null |
['Martin, Julie P.', 'Kander, Ronald G.'] | 2019-09-20T18:18:34Z | 2019-09-20T18:18:34Z | 2000 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/75924', 'http://dx.doi.org/10.26153/tsw/3023'] | eng | 2000 International Solid Freeform Fabrication Symposium | Open | Alloyed | Characterization of Mechanically Alloyed Polymer Blends for Selective Laser Sintering 92 | Conference paper | https://repositories.lib.utexas.edu//bitstreams/312214db-2f70-4871-9184-d32a536cd053/download | null | Cryogenic mechanical alloying (CMA) is presented in this work as an effective technique for creating materials for selective laser sintering (SLS) applications. CMA offers a solid state method for creating micro-composites consisting of finely dispersed phases, which can then be selectively laser sintered into parts containing co-continuous phases. Particle size and shape, microstructure, and melting characteristics of mechanically alloyed particles are discussed in terms of applications to the SLS process. The
characteristics of several model polymer blend systems are investigated using scanning electron microscopy, light scattering particle size analysis, and differential scanning calorimetry. Although only polymer/polymer blend particles are studied here, the CMA process is also a viable technique for creating SLS powders using ceramics or metals. | null | null | null | null | null | null |
['Vu, Ivan', 'Bass, Lindsey', 'Meisel, Nicholas'] | 2021-10-21T15:19:57Z | 2021-10-21T15:19:57Z | 2015 | Mechanical Engineering | null | https://hdl.handle.net/2152/89393 | eng | 2015 International Solid Freeform Fabrication Symposium | Open | ['PolyJet', 'additive manufacturing', 'multi-material fabrication', 'acrylic layers', 'fabrication interface'] | Characterization of Multi-Material Interfaces in PolyJet Additive Manufacturing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/8c95f275-4e1c-4ddc-a012-733d0fe0dcb7/download | University of Texas at Austin | Relatively few engineering devices and structures are monolithic, as combinations of
materials are often needed to obtain the necessary functionality, performance, weight, and cost
requirements. Progress in additive manufacturing now allows multiple materials and even
blends of materials to be produced in a single manufacturing process, opening new opportunities
for expeditiously achieving functional and performance targets. Just as interactions at interfaces
have long been of interest in the area of adhesive bonding, similar issues need to be addressed for
printed composite materials. In this study, a Stratasys PolyJet system was used to produce
configurations consisting of a soft acrylic layers (TangoBlackPlus) sandwiched by two stiffer
acrylic strips (VeroWhitePlus). Several test methods based on the double cantilever beam
specimen, a common experimental approach to characterize adhesive performance, were
evaluated to characterize the fracture resistance of the assembled layers. Failures nominally
occurred at the interface between the two types of materials. Further testing is providing insights
into the effects of print direction, postcuring, and interface architecture on the resulting fracture
energies. These studies suggest the opportunities for designing printed interfaces with improved
performance and durability for multi-material additive manufacturing products. | null | null | null | null | null | null |
['Obielodan, John', 'Vergenz, Kevin', 'Aqil, Danyal', 'Wu, Joseph', 'Ellistrem, Laurel Mc'] | 2021-11-18T02:24:29Z | 2021-11-18T02:24:29Z | 2019 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90414', 'http://dx.doi.org/10.26153/tsw/17335'] | eng | 2019 International Solid Freeform Fabrication Symposium | Open | ['PLA', 'lignin', 'biocomposites', '3D printing', 'sustainability'] | Characterization of PLA/Lignin Biocomposites for 3D Printing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/91a7a0c3-6876-415e-a8a0-61b7e42fdff7/download | University of Texas at Austin | A greater proportion of polymer-based three-dimensional (3D) printing materials are
synthetic petroleum derivatives that are not biodegradable, contributing to environmental
pollution and have potential adverse effects on human health. Polylactic acid (PLA) is currently
the most widely used among the bio-based alternatives. This work explores alternative
environmentally friendly bio-based polymers sourced from sustainable crop and forest biomass
derivatives for 3D printing. Various blends of PLA/Organosolv lignin were extruded for fused
filament fabrication (FFF) 3D printing process. The processing parameters and results of
mechanical and thermal properties of fabricated test specimens of the biocomposite with up to
40wt% lignin concentration are presented. Results indicates that lignin, a low-cost waste product
of pulping for the paper industry and bioethanol fuel production could serve as a key component
of new biocomposite polymers for 3D printing applications. | null | null | null | null | null | null |
['Schmidt, J.', 'Dechet, M.A.', 'Gómez Bonilla, J.S.', 'Hesse, N.', 'Bück, A.', 'Peukert, W.'] | 2021-11-18T01:28:14Z | 2021-11-18T01:28:14Z | 2019 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90393', 'http://dx.doi.org/10.26153/tsw/17314'] | eng | 2019 International Solid Freeform Fabrication Symposium | Open | ['powder characterization', 'polymer powders', 'selective laser sintering'] | Characterization of Polymer Powders for Selective Laser Sintering | Conference paper | https://repositories.lib.utexas.edu//bitstreams/694a86c2-ebd2-46b3-91dd-c4230ce6c7e6/download | University of Texas at Austin | Flowability and packing properties are essential for powder spreading and resulting part properties in
powder bed fusion processes (PBF), such as selective laser sintering (SLS). In this contribution, powder
requirements for SLS, structure-property relationships and appropriate methods for powder characterization are
reviewed. Effects of particle size, particle shape and surface functionalization on flowability, packing density
and tribo-charging will be discussed for commercial PA12 laser sintering powders (virgin vs. aged), polyolefin
and polyester powders. The possibilities of dry particle coating as an efficient method to tailor powder
flowability, bulk density and charging behavior are demonstrated. The capabilities of a Schulze ring shear
tester, a powder tensile strength tester, a thermally controllable ring shear apparatus and a model experiment
mimicking the powder spreading are discussed to assess SLS processability. | null | null | null | null | null | null |
['Bhat, V.V.', 'Geetha, K.', 'Das, R.N.', 'Gurumoorthy, B.', 'Umarji, A.M.'] | 2019-09-18T16:50:56Z | 2019-09-18T16:50:56Z | 2000 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/75902', 'http://dx.doi.org/10.26153/tsw/3002'] | eng | 2000 International Solid Freeform Fabrication Symposium | Open | Alumina | Characterization of Polyolefin – Alumina compounded mix for FDC processing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/bf000f96-90fe-4071-b585-3719ffe8c943/download | null | Fused deposition of ceramics (FDC) uses thermoplastic binder and ceramic blend as
feed material. The geometry of the fused deposition machine restricts the workability of the
FDC feed material, which is in the form of a filament. The feasibility of the usage of these
filaments is mainly based on the viscosity at the working temperature and the compressive
modulus of the feed material at near room temperature. The polymers based on Polyethylene
(PE), having two molecular weights 3,000 (LDWAX) and 341,000 (LDPE) were mixed in
various weight proportions by solvent method using toluene as solvent, to develop a binder
system for Fused Deposition Modeling of alumina. Variation of viscosity as a function of
composition, temperature and solid loading was measured using spindle viscometer and
capillary rheometer. Dilatometric thermal expansion of 50 Vol% alumina compounded
binders is measured up to 120°C. The pronounced softening of the compounded mixture is
observed beyond 70°C, when the volume % of LDWAX is in excess of 50% total binder
content. The compression strength decreases from 720 N to 310 N for pellet having 1.2cm
diameter and 1.5 aspect ratio, when the percentage of LDWAX varies from 40 to 70% in the
binder composition. The suitability of the compounded mix of LDWAX and LDPE binder
with 40 Vol. % alumina for FDC is being evaluated in a StratasysTM1600 machine. | null | null | null | null | null | null |
['Gornet, T.J.', 'Davis, K.R.', 'Starr, T.L.', 'Mulloy, K.M.'] | 2019-10-25T16:07:18Z | 2019-10-25T16:07:18Z | 2002 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/77442', 'http://dx.doi.org/10.26153/tsw/4531'] | eng | 2002 International Solid Freeform Fabrication Symposium | Open | Laser Sintering | Characterization of Selective Laser Sintering™ Materials to Determine Process Stability | Conference paper | https://repositories.lib.utexas.edu//bitstreams/e2aca76a-6a16-4e21-9e92-f835aad687e3/download | null | The Selective Laser Sintering (SLS) process has proved to be an excellent method for
prototyping functional parts out of engineering thermoplastics such as polyamides. However, the
material undergoes physical and chemical changes due to repeated heating cycles in the SLS
equipment. This causes variations in powder characteristics and performance in the SLS process.
With the increased utilization of SLS for direct manufacturing it is necessary to develop a
characterization and testing system that can determine powder fitness to ensure process stability
and part quality. Current powder recycling methodologies use an average virgin-to-used powder
mixture. In a new approach, a testing mechanism to deliver a numerical, measurable material
characterization will be discussed. Experimental results of repeated reuse of material and its
resulting physical effects on mechanical properties, shrinkage, and chemical tests will be
presented. A definitive testing and measurement process control will be shown to improve
process stability and thus part quality and consistency. | null | null | null | null | null | null |
['Kambly, Kiran', 'Yuan, Dajun', 'Shao, Peng', 'Das, Suman'] | 2021-09-28T19:06:03Z | 2021-09-28T19:06:03Z | 2009-09 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88156', 'http://dx.doi.org/10.26153/tsw/15097'] | eng | 2009 International Solid Freeform Fabrication Symposium | Open | ['Large Area Maskless Photopolymerization', 'polymerization shrinkage', 'polymerization stresses', 'ceramic molds'] | Characterization of Shrinkage and Stresses in Large Area Maskless Photopolymerization | Conference paper | https://repositories.lib.utexas.edu//bitstreams/45440075-7fec-4ff5-9262-011db5946b63/download | University of Texas at Austin | Large Area Maskless Photopolymerization (LAMP) is a high throughput direct digital
manufacturing technology being developed for producing ceramic investment casting molds.
Polymerization shrinkage and accompanying stresses developed during photopolymerization of
ceramic particle-loaded resins in LAMP can cause deviations from the desired geometry. The
extent of deviations depends on photoinitiator concentration, filler loading, degree of monomer
conversion and operating parameters such as energy dose. An understanding of shrinkage and
stresses built up in the part can assist in developing source geometry compensation algorithms
and exposure strategies to alleviate these effects. Real-time Fourier Transform Infrared
Spectroscopy (RTFTIR) operated in Attenuated Total Reflectance (ATR) mode is used to
characterize the three-dimensional shrinkage stresses. This work is sponsored by DARPA Grant
HR0011-08-1-0075. | null | null | null | null | null | null |
['Mei, H.', 'Valant, M.', 'Hu, D.', 'Kovacevic, R.'] | 2019-10-24T18:20:03Z | 2019-10-24T18:20:03Z | 2002 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/77417', 'http://dx.doi.org/10.26153/tsw/4506'] | eng | 2002 International Solid Freeform Fabrication Symposium | Open | Powder Feeder | The Characterization of the Performance of a New Powder Feeder for Laser Based Additive Manufacturing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/d5d91adf-8a0c-47ea-80f3-b27976669aed/download | null | Laser-based additive manufacturing (LBAM) requires precise control over the metal,
ceramic, or carbide powder added to the molten pool. The feeding rate of the powder must
be very consistent, and it must respond rapidly to commands to change the feeding rate.
LBAM also requires feeding rates as low as one gram per minute. Currently, commercially
available powder feeders are optimized for such tasks as feeding powder to thermal
spraying processes, which generally require a much higher feeding rate than LBAM, and
can usually tolerate much more variation in the feeding rate. These powder feeders are
therefore not suitable for the LBAM process. The Research Center for Advanced
Manufacturing at Southern Methodist University has designed and built a new powder
feeder capable of consistent, repeatable powder delivery at extremely small flow rates. The
powder feeder is regulated by a weight-based control system, which provides real-time
measurement of the mass remaining in the feeder as powder is transferred to the powder
nozzles. The powder feeder has been fully characterized to obtain correlations between the
input parameters, powder type and the resulting mass flow rates. The powder nozzles at the
laser head have also been characterized. The nozzle angle, standoff height, and carrier gas
flow rate have each been optimized experimentally to maximize the concentration of
powder arriving at the molten pool created by the laser beam, as detected using a sheet of
He-Ne laser light and a coaxial vision system. The powder delivery efficiency of the
system has been thus maximized, increasing both the deposition rate and the quality of the
deposited material. | This work was financially supported by THECB, Grants 003613-0022-1999 and 03613-
0016-2001, NSF, Grants No. DM1-9732848 and DM1-9809198, and the U.S. Department
of Education, Grant No. P200A80806-98. | null | null | null | null | null |
['Cormier, Denis', 'West, Harvey', 'Harrysson, Ola', 'Knowlson, Kyle'] | 2020-02-14T15:28:40Z | 2020-02-14T15:28:40Z | 2004 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/79985', 'http://dx.doi.org/10.26153/tsw/7010'] | eng | 2004 International Solid Freeform Fabrication Symposium | Open | Electron Beam Melting | Characterization of Thin Walled Ti-6Al-4V Components Reduced via Electron Beam Melting | Conference paper | https://repositories.lib.utexas.edu//bitstreams/2a943c0a-34ee-4ca2-84a5-8972863f6764/download | null | Direct-metal energy beam SFF processes typically produce layers by scanning the
contours and then filling in the area within the contour. Process parameters used to solidify
contours are often different from those for fill areas. It is to be expected, therefore, that the
contour and fill area regions will have different microstructures. This can have important
ramifications for thin walled components such as biomedical implants whose slices have very
little fill area. This paper characterizes the metallurgical differences in contour and fill areas in
titanium components produced via Electron Beam Melting. The implications of these properties
for thin walled components are described. | null | null | null | null | null | null |
['Linn, John', 'Weaver, Jason M.', 'Miles, Michael P.', 'Hovanski, Yuri'] | 2021-11-10T22:44:59Z | 2021-11-10T22:44:59Z | 2018 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90197', 'http://dx.doi.org/10.26153/tsw/17118'] | eng | 2018 International Solid Freeform Fabrication Symposium | Open | ['strength property', 'interfacial bonds', 'interface', 'hybrid manuufacturing', 'metal additive manufacturing'] | Characterizing Interfacial Bonds in Hybrid Metal AM Structures | Conference paper | https://repositories.lib.utexas.edu//bitstreams/e470ae43-3637-4808-b9f3-f32a6456c913/download | University of Texas at Austin | The capabilities of various metal Additive Manufacturing (AM) processes, such as
Powder Bed Fusion - Laser (PBF-L) are increasing such that it is becoming ever more common
to use them in industrial applications. The ability to print atop a substrate broadens that scope of
applications. There is ongoing research regarding the mechanical properties of additively
processed materials, but not much regarding the interaction between additive material and its
substrate. An understanding of the mechanical and performance properties of the AM/substrate
interface is imperative. This paper describes a study of the strength properties of AM/substrate
interfaces, with respect to torsion and tension, and compares them to their fully wrought and
fully additive counterparts. | null | null | null | null | null | null |
['Mattingly, Frye L.', 'Franc, Alan', 'Kunc, Vlastimil', 'Duty, Chad'] | 2021-12-01T23:38:42Z | 2021-12-01T23:38:42Z | 2021 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90659', 'http://dx.doi.org/10.26153/tsw/17578'] | eng | 2021 International Solid Freeform Fabrication Symposium | Open | ['internal porosity', 'fiber reinforced materials', '3D printing', 'big area additive manufacturing', 'BAAM'] | Characterizing Internal Porosity of 3D-Printed Fiber Reinforced Materials | Conference paper | https://repositories.lib.utexas.edu//bitstreams/f6ed67dc-8a25-4159-808b-e8d18911d55f/download | University of Texas at Austin | As the functional requirements for 3D printed parts become more demanding, the use of fiber
reinforced materials in material extrusion printers is increasingly common. Although fiber-reinforced thermoplastics offer higher stiffness and strength, the internal volume of the extruded
material often has a high degree of porosity which can negatively impact mechanical properties.
This research surveys the internal porosity present across a range of material extrusion additive
manufacturing platforms, primarily those involving a single screw extruder, such as the Big Area
Additive Manufacturing (BAAM) system. The porosity within the volume of an extruded bead
was quantified through image analysis of cross sectional micrographs. The impact of extrusion
rate, transient vs steady state flow, multiple hardware configurations, and material conditions were
evaluated. Across the five systems studied porosities ranged from 0.1% to 18.4% with the greatest
reductions in porosity coming from two systems that added a vent to the extruder barrel which
lowered porosity 64% in one case and 98% in the other. | null | null | null | null | null | null |
['Sudbury, Zeke', 'Duty, Chad', 'Kunc, Vlastimil', 'Kishore, Vidya', 'Ajinjeru, Christine', 'Failla, Jordan', 'Lindahl, John'] | 2021-10-27T21:50:18Z | 2021-10-27T21:50:18Z | 2016 | Mechanical Engineering | null | https://hdl.handle.net/2152/89627 | eng | 2016 International Solid Freeform Fabrication Symposium | Open | ['functionally graded materials', 'large scale additive manufacturing', 'additive manufacturing', 'optimization'] | Characterizing Material Transition for Functionally Graded Material Using Big Area Additive Manufacturing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/ddd453d1-f898-4bbb-8b9d-afc7521b782c/download | University of Texas at Austin | This study examines functionally graded materials (FGM) on a polymer based large scale
additive manufacturing system. FGM utilizes a less expensive material with sub-optimal
mechanical properties for the majority of the part, and uses more expensive higher performance
material in selected areas. This process aims to optimize cost with weight and mechanical
performance. FGM is already used a variety of industries, but is not common place in additive
manufacturing, specifically large scale additive manufacturing like Cincinnati Incorporated’s Big
Area Additive Manufacturing (BAAM). BAAM can use a variety of plastic injection molding
and extrusion style polymer pellets, which allows it to use both commodity materials and high
performance engineering polymers. This study is an initial assessment of FGM using glass fiber
reinforced ABS and carbon fiber reinforced ABS, and characterizes the performance of a density
gradient shape function to characterize the blending of materials. | null | null | null | null | null | null |
['Ziegelmeier, Stefan', 'Wöllecke, Frank', 'Tuck, Christopher', 'Goodridge, Ruth'] | 2021-10-07T18:49:25Z | 2021-10-07T18:49:25Z | 8/16/13 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88503', 'http://dx.doi.org/10.26153/tsw/15437'] | eng | 2013 International Solid Freeform Fabrication Symposium | Open | ['powder bed fusion', 'polyurethane', 'powders', 'laser sintering', 'flow properties', 'bulk behaviour'] | Characterizing the Bulk & Flow Behaviour of LS Polymer Powders | Conference paper | https://repositories.lib.utexas.edu//bitstreams/12e26f4c-fc5a-45d1-b44f-4c33a3b742e9/download | University of Texas at Austin | The properties of laser sintering (LS) powders affect processability and the quality of parts
manufactured. This study compared three different methods used to quantify both the static
and dynamic powder properties – a Revolution Powder Analyzer, FT-4 Powder Rheometer
and Hausner Ratio. The aim of the work was to identify the most reliable method to
characterize powder properties in correlation to the dynamic conditions that occur during LS.
The experiments focused on different particle size distributions of a cryogenically ground
polyurethane powder compared to a standard polyamide 12 LS material, PA2200. The results
have led to a deeper understanding regarding powder interactions and therefore serve as input
for material design and quality assurance. | null | null | null | null | null | null |
['Brackett, James', 'Cauthen, Dakota', 'Condon, Justin', 'Smith, Tyler', 'Gallego, Nidia', 'Kunc, Vlastamil'] | 2021-11-18T01:25:23Z | 2021-11-18T01:25:23Z | 2019 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90392', 'http://dx.doi.org/10.26153/tsw/17313'] | eng | 2019 International Solid Freeform Fabrication Symposium | Open | ['print parameters', 'volumetric porosity', 'mechanical performance', 'density', 'extrusion deposition additive manufacturing'] | Characterizing the Influence of Print Parameters on Porosity and Resulting Density | Conference paper | https://repositories.lib.utexas.edu//bitstreams/c61433d3-ae61-448e-9a34-9f1b01b33495/download | University of Texas at Austin | Extrusion deposition additive manufacturing produces parts with inherent porosity, which
typically manifests as easily accessible voids between beads. This open porosity can also be
accompanied by voids within the beads themselves, and both types can impact a part’s desired
performance. Porosity is influenced by a variety of factors, including infill percentage, layer
height, nozzle diameter, print speed, and raster orientation. While their influence on mechanical
properties and porosity have been studied previously, there has been minimal work connecting
print parameters to porosity and subsequently to mechanical performance. This study
investigates the relationships between print parameters, volumetric porosity, and mechanical
performance. In addition, this study measures both open and closed porosity through use of a
helium pycnometer rather than image analysis of a cross-section. Thus, this study will identify
correlations between the volumetric density of parts and the resulting mechanical performance as
a function of print parameters. | null | null | null | null | null | null |
['Brackett, James', 'Hussein, Zaky', 'Charles, Elijah', 'Smith, Tyler', 'Hassen, Ahmed', 'Kim, Seokpum', 'Kunc, Vlastimil', 'Duty, Chad'] | 2021-12-06T21:40:47Z | 2021-12-06T21:40:47Z | 2021 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90681', 'http://dx.doi.org/10.26153/tsw/17600'] | eng | 2021 International Solid Freeform Fabrication Symposium | Open | ['internal structure', 'transition regions', 'characterization', 'CF-ABS', 'big area additive manufacturing'] | Characterizing the Internal Morphology of Transition Regions in Large-Scale Extrusion Deposition Additive Manufacturing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/92528331-aadb-42b8-b5ed-fa54cfa156c0/download | University of Texas at Austin | A dual-hopper feed system that was developed for the Big Area Additive Manufacturing
(BAAM) system allows for transitioning between different materials while maintaining continuous
deposition. This technique creates a step-change in material feedstock by switching the pellet
feeding system to alternate which hopper is currently supplying material, allowing for multi-material construction. The step-change in feedstock material produces a transition region that is
characterized by a compositional gradient and blended internal morphology. Initial cross-sectional
imaging of the transition region revealed a non-homogenous blend of materials with distinct
domains of each material, likely due to incomplete mixing within the screw. This study used a
carbon fiber reinforced acrylonitrile butadiene styrene (CF-ABS) and an unfilled ABS to
characterize the internal structure and to correlate it to mechanical performance by tracking
microhardness across cross-sections of the transition region. | null | null | null | null | null | null |
['Corum, Tyler', 'O’Connell, Johnna', 'Brackett, James', 'Spencer, Ryan', 'Hassen, Ahmed', 'Duty, Chad'] | 2023-02-10T17:51:42Z | 2023-02-10T17:51:42Z | 2022 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/117457', 'http://dx.doi.org/10.26153/tsw/44338'] | eng | 2022 International Solid Freeform Fabrication Symposium | Open | polymer | Characterizing the Thermal-Induced Distortion of Large-Scale Polymer Composite Printed Structures | Conference paper | https://repositories.lib.utexas.edu//bitstreams/85b1f5ca-7b14-455b-a908-5983fc74216e/download | null | The Big Area Additive Manufacturing (BAAM) system has been used to print large-scale
parts, such as automotive structures and molds for tooling, with fiber-reinforced polymer
composites. Incorporating reinforcing fibers in printed parts is commonly used to increase
stiffness and strength, but it also introduces significant anisotropy in the thermomechanical
performance, which can lead to distortion and warping during thermal cycling. Characterizing and
understanding how a printed tool distorts is crucial to maintaining tolerances and avoiding part
failure. This study uses digital image correlation (DIC) to measure the coefficient of thermal
expansion (CTE) of a printed part from room temperature and to a known steady state temperature.
The samples were printed with carbon fiber reinforced acrylonitrile butadiene styrene (CF-ABS).
Various nozzle geometries were evaluated in this study with the intent of minimizing the thermal-
induced distortion experienced by printed parts. | null | null | null | null | null | null |
['Corum, Tyler', "O'Connell, Johnna", 'Heres, Maximilian', 'Foote, Jeff', 'Duty, Chad'] | 2024-03-27T03:39:58Z | 2024-03-27T03:39:58Z | 2023 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/124471', 'https://doi.org/10.26153/tsw/51079'] | en_US | 2023 International Solid Freeform Fabrication Symposium | Open | ['large-format additive manufacturing', 'LOCI-One', 'thermomechanics'] | CHARACTERIZING THERMOMECHANICAL PROPERTIES OF LARGE-FORMAT PRINTED COMPOSITE POLYMER STRUCTURES | Conference paper | https://repositories.lib.utexas.edu//bitstreams/87225841-2356-4230-a038-79f36e980450/download | University of Texas at Austin | Large-format additive manufacturing (LFAM) is a manufacturing technique where a high
volume of material is extruded in a layer-by-layer fashion to form structures that typically measure
several meters in scale. The LOCI-One system is an LFAM-type system operated by Loci
Robotics, Inc. that features a high throughput extruder mounted on a 6-axis robot arm. This
research used the LOCI-One system to print single bead walls of 20% by weight carbon fiber
reinforced acrylonitrile butadiene styrene (CF-ABS) at various layer deposition methods, print
speed, layer times, and bead widths. The coefficient of thermal expansion (CTE) of the printed
structures was measured to quantify effects of print conditions on thermomechanical performance.
The CTE of the LFAM printed walls was measured using a large-scale digital image correlation
system to characterize the distortion of the fiber reinforced composite material in the x- (print
direction) and z- (between layers) directions. This study determined that with varying print
parameters the CTE measured in the x-direction was largely influenced by bead geometry with the
CTE measured in the z-direction relatively unaffected by either the varying parameters or the
method in which layer deposition occurred. | null | null | null | null | null | null |
['Bai, Di', 'Patil, Vineeth R.', 'Esterman, Marcos', 'Chang, Shu'] | 2021-10-13T20:11:27Z | 2021-10-13T20:11:27Z | 2014 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88775', 'http://dx.doi.org/10.26153/tsw/15709'] | eng | 2014 International Solid Freeform Fabrication Symposium | Open | ['unconsolidated powders', 'electrophotographic printing toner', 'three-dimensional microstructures', 'additive manufacturing'] | Characterizing Three Dimensional Microstructures Formed by Particles: An Example of Electrophotographic Printing Toner | Conference paper | https://repositories.lib.utexas.edu//bitstreams/43498dfa-ab17-464e-a1f2-abdbbf87d5dd/download | University of Texas at Austin | Additive manufacturing of objects using powders can result in microscopic structures based on the
properties of particles used. In additive manufacturing, piles of powder are consolidated by one or other
mechanisms in order to form a part. The resulting microstructure within the part can impact its engineering
performance. Predicting and controlling the engineering performance requires the characterization of the
part’s material interior microstructures. H owever, obtaining the microstructure is difficult since the
interior of a powder is a challenge to visualize.
In this paper, unconsolidated powders are characterized. We have used Confocal Laser Scanning
Microscopy to image three-dimensionally sediments of micron-sized poly-dispersed electro-photographic
printing particles. Using image analysis tools, we have extracted each particle’s position and radius in
selected sampling volumes. Through this methodology, we demonstrate the possibility to recreate the
three-dimensional particle structures and extract values for morphological parameters for powder systems.
The feasibility of direct and quantitative particle structural characterization can lead to much needed
methods and tools to relate particle structures to the process of fabrication, the design of materials, and
product performance in additive manufacturing. | null | null | null | null | null | null |
['Barroi, A.', 'Hermsdorf, J.', 'Kling, R.'] | 2021-10-04T21:05:49Z | 2021-10-04T21:05:49Z | 8/17/11 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88346', 'http://dx.doi.org/10.26153/tsw/15285'] | eng | 2011 International Solid Freeform Fabrication Symposium | Open | ['GMA cladding', 'additive manufacturing', 'laser deposition'] | Cladding and Additive Layer Manufacturing with a Laser Supported Arc Process | Conference paper | https://repositories.lib.utexas.edu//bitstreams/3cab5849-e3b4-48ac-93a8-9c34d440849f/download | University of Texas at Austin | This paper describes the potential of a new process, combining the geometrical
precision of a laser technique and the deposition rates of GMA cladding. Dilutions as low
as 3 % can be achieved, leading to a high purity, in the first layer. Different material
combinations like mild steel with X45CrSi9-3 are presented. Microsections for
penetration depth determination show the high quality of the deposition layers. A
hardness of the coatings of 63 HRC is reached. Hardfacing of shafts serve as an
application example. The low heat input enables the process to build up structures. This
results in a process variant for additive layer manufacturing which is also presented. The
production of macro-sized structures is shown and discussed. | null | null | null | null | null | null |
['Mischliwski, S.', 'András, D.', 'Weigold, M.'] | 2023-04-05T13:39:09Z | 2023-04-05T13:39:09Z | 2022 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/117772', 'http://dx.doi.org/10.26153/tsw/44651'] | eng | 2022 International Solid Freeform Fabrication Symposium | Open | ['flexible clamping concept', '6-side machining', 'hybrid manufacturing'] | Clamping Concept for 6 Side Hybrid Manufacturing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/55480564-5136-46e8-8590-739fc81d25a4/download | null | For most technical applications, the surface quality and tolerances that result directly from additive
processes are not suitable. Hybrid manufacturing as a combination of additive and subtractive manufacturing
process steps can help solving this issue. In this work, a conceptional adjustable cast clamping process is
introduced for a combination of Laser-based Powder-Bed-Fusion (LPBF) and milling. For component clamping
during the milling process, the components are cast in place with a low-melting metal alloy, creating form-fit and
force-fit connection. To prove the applicability, a rough estimation of occurring milling forces was conducted. In
a subsequent series of tests, validation of clamping force was carried out using complex part geometries. A
prototype fixture designed for this cast clamping process has been developed and tested. This fixture allows
complex non-restricted 6-side machining of parts without moving it relative to the fixture or the need of any
additional manual rework on part surfaces. | null | null | null | null | null | null |
['Shafer, C.S.', 'Siddel, D.H.', 'Merriman, A.L.', 'Elliott, A.M.'] | 2021-10-28T19:38:05Z | 2021-10-28T19:38:05Z | 2016 | Mechanical Engineering | null | https://hdl.handle.net/2152/89679 | eng | 2016 International Solid Freeform Fabrication Symposium | Open | ['fused deposition modeling', 'cleated print surface', 'build platform'] | Cleated Print Surface for Fused Deposition Modeling | Conference paper | https://repositories.lib.utexas.edu//bitstreams/e39704a0-3d3b-4b6f-9592-8f118c6b6cb0/download | University of Texas at Austin | Fused Deposition Modeling (FDM) has become popular among Additive Manufacturing
technologies due to its low cost, speed, and geometric scalability; however, the primitive nature
of the FDM build surface fundamentally limits the utility of FDM in terms of reliability,
autonomy, and material selection. Currently, FDM relies on adhesive forces between the first
layer of a print and the build surface; depending on the materials involved, this adhesive bond
may or may not be reliable. Thermal contraction between the build plate and build materials can
break that bond, which causes warpage and delamination of the part from the build surface and
subsequent failure of the part. Furthermore, with each print, the user must use tools or special
maneuvering to separate the printed part from the build surface as well as retexture or replace the
used build surface. In this paper we present a novel build platform that allows for a mechanical
bond between the print and build surface by using dovetail-shaped features. The first layer of the
print flows into the features and becomes mechanically captivated by the build platform. Once
the print is completed, the platform is rolled or flexed open to release the part from the
mechanical bond. This design not only lowers the risk of delamination during printing but also
eliminates the need for a user to reset or replace the build surface between print jobs. The
effectiveness of each geometry was determined by measuring the distance at the pinch point
compared to the distance that the extrusion filled below the pinch point. The Captivation Ratio
was measured to compare the different geometries tested and determine which direction of
extrusion creates a better ratio. | null | null | null | null | null | null |
['Kirschman, Jill S.', 'Kirschman, Charles F.', 'Fadel, Georges M.', 'Greenstein, Joel S.'] | 2018-12-06T22:09:45Z | 2018-12-06T22:09:45Z | 1997 | Mechanical Engineering | doi:10.15781/T2DN40G3K | http://hdl.handle.net/2152/71435 | eng | 1997 International Solid Freeform Fabrication Symposium | Open | ['Rapid Prototyping', 'CAD'] | The Clemson Intelligent Design Environment For Stereolithography-Cides 2.0 | Conference paper | https://repositories.lib.utexas.edu//bitstreams/55770349-4ef7-4a75-b17a-cfb5bdcbc9fa/download | null | There are a large number of commercial Rapid Prototyping (RP) devices available today. All
ofthese machines begin with a Computer-Aided Design (CAD) model, which is tessellated,
sliced and then built layer-by-Iayer on the RP device. All ofthese operations, except the actual
building ofthe part, are completed on a computer. Therefore, many improvements to the RP
processes can be achieved through software, without affecting the RP devices or the warranties
on them. This has led to the development of a front-end software product to support the task of
preparing the part to be built. The Clemson Intelligent Design Environment for
Stereolithography (CIDES) is a user-centered interface between the CAD system and RP
systems, primarily the Stereolithography Apparatus (SLA).
CIDES 2.0 is designed to provide a variety oftools which are valuable to the users ofRP
systems, including the ability to view and modify tessellated (STL) files, generate supports, and
slice STL files into layer (SLI) files for use on an SLA. It also provides the ability to view SLI
and merged (V) files. Furthermore, CIDES offers additional translation capabilities that make it
valuable for other RP processes. The package has proven useful in the Laboratory to Advance
Industrial Prototyping (LAIP) at Clemson University. CIDES 2.0 is a new X Windows-based
release based on the original version ofCIDES with many additional features. A new HumanComputer
Interface is the major improvement to this release. | null | null | null | null | null | null |
['Rogers, Bill', 'Gitter, Andrew', 'Bosker, Gordon', 'Faustini, Mario', 'Lokhande, Mahendra', 'Crawford, Richard'] | 2019-10-18T16:40:30Z | 2019-10-18T16:40:30Z | 2001 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/76256', 'http://dx.doi.org/10.26153/tsw/3345'] | eng | 2001 International Solid Freeform Fabrication Symposium | Open | Prosthetic | Clinical Evaluation of Prosthetic Sockets Manufactured by Selective Laser Sintering | Conference paper | https://repositories.lib.utexas.edu//bitstreams/b98de382-bf7e-44e3-9c03-2695bef67306/download | null | A pilot study was undertaken to evaluate the clinical acceptance of prosthetic limb sockets
manufactured using solid freeform fabrication (SFF). The fabrication of sockets for amputees is a
natural application for SFF. The socket is the part of the prosthetic limb that fits onto the
amputee’s residual limb. Each socket is custom manufactured for each individual amputee. Four
amputees were successfully fit with sockets created using selective laser sintering. The scope of
the study included software development, finite element analysis, materials testing, and clinical
evaluation. This paper discusses socket design issues and clinical testing results. | null | null | null | null | null | null |
['Hu, D.', 'Mei, H.', 'Tao, G.', 'Kovacevic, R.'] | 2019-10-09T16:24:43Z | 2019-10-09T16:24:43Z | 2001 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/76156', 'http://dx.doi.org/10.26153/tsw/3245'] | eng | 2001 International Solid Freeform Fabrication Symposium | Open | Cladding | Closed Loop Control of 3D Laser Cladding Based on Infrared Sensing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/473bfd2b-6cd9-46b3-b178-68a2dc5fcd8c/download | null | In this paper, a heat input closed-loop control system based on infrared image sensing for 3D
laser cladding is introduced. A high frame-rate (up to 800 frames/s) camera is installed coaxially
on the top of the laser-nozzle setup. Complete of the infrared images of the molten pool can be
acquired with a short nozzle-substrate distance in different scanning directions, eliminating the
noise from the metal powder. The characteristics of the images show a clear relationship with the
parameter variations of the cladding process. A closed-loop control system is built based on the
feedback of the infrared image sensing. The control results show a great improvement in the
geometrical accuracy of the part being built | This work was financially supported by THECB, Grant 003613-0022-1999, NSF, Grants
No. DM1-9732848 and DM1-9809198, and the U.S. Department of Education, Grant No.
P200A80806-98. | null | null | null | null | null |
['Hartman, Aja', 'Zhao, Zhao'] | 2023-01-27T17:41:55Z | 2023-01-27T17:41:55Z | 2022 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/117343', 'http://dx.doi.org/10.26153/tsw/44224'] | eng | 2022 International Solid Freeform Fabrication Symposium | Open | Additive manufacturing | Closed Loop Control Utilizing In-situ Pattern Printing and Reading for Quality Level Determination in Additive Manufacturing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/65605e8f-9d92-4ff2-9f50-4ce299debab8/download | null | HP’s Multi Jet Fusion (MJF) is a powder-based technology that selectively melts
polymer powder, using a fusing agent, in a layer-by-layer fashion to create 3D parts. One of
the challenges for wide adoption of additive manufacturing is the assurance of the print process
and part consistency through a cost-effective and non-destructive fashion. Non-destructive part
quality measurements can be achieved through a method of printing two-dimensional patterns
at desired locations throughout the part. The readability of these patterns provides either the
signals to actuate process changes during the print or information on part quality during and
after printing. This method can also be used for covert part marking to provide design
intellectual property security. | null | null | null | null | null | null |
['Thompson, N.R.', 'Weaver, J.M.'] | 2023-03-30T16:23:25Z | 2023-03-30T16:23:25Z | 2022 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/117703', 'http://dx.doi.org/10.26153/tsw/44582'] | eng | 2022 International Solid Freeform Fabrication Symposium | Open | PETG | Closed Loop Recycling of PETG in Fused Granule Fabrication Large Area Additive Manufacturing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/5ff8c5b9-c258-458e-bea2-d372d41414fb/download | null | Plastic waste is a critical worldwide problem that impacts additive manufacturing (AM).
Extensive research has explored how plastic waste in AM can be reduced by recycling prints into
new filament, with varying success. An alternative to filament-based extrusion is “fused granule
fabrication” (FGF), which extrudes from pellets or granules. This method is often used for large
area additive manufacturing (LAAM) of polymers. This paper expands upon the knowledge base
from previous research on LAAM and examines the extent to which PETG can be recycled and
reprinted through the same FGF tool without significant loss to its material properties. The metric
used for comparing material properties is tensile testing along the direction of deposition. Recycled
material was granulized, filtered, and dehydrated. This resulted in effective printing of 100%
recycled PETG, with recycled samples demonstrating 83% of the tensile strength of virgin PETG. | null | null | null | null | null | null |
['Cholewa, S.', 'Jaksch, A.', 'Drummer, D.'] | 2023-03-29T14:49:01Z | 2023-03-29T14:49:01Z | 2022 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/117675', 'http://dx.doi.org/10.26153/tsw/44554'] | eng | 2022 International Solid Freeform Fabrication Symposium | Open | PBF-LB/P | Coalescence Behavior of Polyamide 12 as Function of Zero-Shear Viscosity and Influence on Mechanical Performance | Conference paper | https://repositories.lib.utexas.edu//bitstreams/b4763654-ac9f-4dc2-b788-9da23bcc0575/download | null | The favored material for powder bed fusion of polymers (PBF-LB/P) is polyamide-12. Its molecular weight
increases from post-condensation at elevated temperatures in the building chamber, consequently having different
properties when reused. An important aspect of PBF directly affected hereby is the coalescence behavior, as it
significantly determines the surface quality, porosity, and thus the component’s mechanical properties. However,
detailed studies on coalescence are limited to virgin powders with low viscosity; therefore, coalescence behavior
of polyamide-12 with different molecular weights is investigated using hot stage microscopy. Additionally, the
zero-shear viscosity is determined using the Carreau model, allowing comparison of experimental results to
sintering models. Furthermore, the mechanical properties and surface qualities are analyzed, and components with
adequate values are made with two-cycle reprocessed powder. Since surface flaws do not exist uniformly across
all components, the orange peel effect is not attributed solely to the increased viscosity of the reused powder. | null | null | null | null | null | null |
['Liu, Zhien', 'Suppakarn, N.', 'Cawley, James D.'] | 2019-03-17T13:39:50Z | 2019-03-17T13:39:50Z | 1999 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/73698', 'http://dx.doi.org/10.26153/tsw/840'] | eng | 1999 International Solid Freeform Fabrication Symposium | Open | ['CAM-LEM', 'solid freeform'] | Coated Feedstock for Fabrication of Ceramic Parts by CAM-LEM | Conference paper | https://repositories.lib.utexas.edu//bitstreams/6e4ba2d9-2e3e-4274-9afb-0976c75fc044/download | null | In laminated object manufacturing of ceramic components, lamination is one of the most
important materials issues. Good lamination ensures monolithic component after firing.
Otherwise, lamination defects that inevitably will occur in the parts will affect the
properties of ceramic components. Adhesive (both liquid and non-liquid) lamination
processes were developed for the cut-then-stack (CAM-LEM) procedure. The non-liquid
adhesive lamination is discussed in detail. | null | null | null | null | null | null |
['Ming, Ling Wai', 'Gibson, Ian'] | 2019-09-23T15:44:44Z | 2019-09-23T15:44:44Z | 2000 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/75942', 'http://dx.doi.org/10.26153/tsw/3041'] | eng | 2000 International Solid Freeform Fabrication Symposium | Open | Prototyping | Colour Rapid Prototyping Based on SLS Process 227 | Conference paper | https://repositories.lib.utexas.edu//bitstreams/e109bfec-ecab-40e7-a341-aad916f9d002/download | null | Currently, the colour of parts made by the Selective Laser Sintering (SLS) process depends on the colour of the material used. SLS cannot make multiple coloured prototypes because only homogeneous powder (or powder composites) can be used during the process. In this paper, an ink-jet based mechanism is designed to print multiple colours onto the prototypes. The surface tension of conventional ink used in bubble jet printers is so high that it cannot penetrate into the SLS powders. To reduce the surface tension, ethanol is added to it. The ratio of ink to ethanol for necessary penetration is determined by experiments. This paper will go on to describe how the ink affects the structure of SLS materials. The effect of temperature on the penetration of ink into powders will also be discussed. | null | null | null | null | null | null |
['Budde, L.', 'Merkel, P.', 'Prasanthan, V.', 'Bährisch, S.', 'Faqiri, M.Y.', 'Lammers, M.', 'Stonis, M.', 'Hermsdorf, J.', 'Hassel, T.', 'Uhe, J.', 'Behrens, B.-A.', 'Breidenstein, B.', 'Overmeyer, L.'] | 2023-04-03T15:43:50Z | 2023-04-03T15:43:50Z | 2022 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/117719', 'http://dx.doi.org/10.26153/tsw/44598'] | eng | 2022 International Solid Freeform Fabrication Symposium | Open | ['Laser hot-wire cladding', 'Cladding', 'Hot forming', 'Residual stress', 'Microstructure', 'Hardness', 'Tailored Forming'] | Combination of Cladding Processes with Subsequent Hot Forming as a New Approach for the Production of Hybrid Components | Conference paper | https://repositories.lib.utexas.edu//bitstreams/cd9341c6-07be-4640-9c51-e23870b877b6/download | null | A new process chain for the manufacturing of load-adapted hybrid components is presented. The "Tailored
Forming” process chain consists of a deposition welding process, hot forming, machining and an optional heat
treatment. This paper focuses on the combination of laser hot-wire cladding with subsequent hot forming to
produce hybrid components. The applicability is investigated for different material combinations and component
geometries, e.g. a shaft with a bearing seat or a bevel gear. Austenitic stainless steel AISI 316L and martensitic
valve steel AISI HNV3 are used as cladding materials, mild steel AISI 1022M and case hardening steel AISI 5120
are used as base materials. The resulting component properties after laser hot-wire cladding and hot forming such
as hardness, microstructure and residual stress state are presented. In the cladding and the heat-affected zone, the
hot forming process causes a transformation from a welding microstructure to a fine-grained forming
microstructure. Hot forming significantly affects the residual stress state in the cladding the resulting residual
stress state depends on the material combination. | null | null | null | null | null | null |
Boudreaux, J.C. | 2020-02-17T14:25:29Z | 2020-02-17T14:25:29Z | 2004 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/79997', 'http://dx.doi.org/10.26153/tsw/7022'] | eng | 2004 International Solid Freeform Fabrication Symposium | Open | planar slices | A Combinatorial Parametric Engineering Model for Solid Freeform Fabrication | Conference paper | https://repositories.lib.utexas.edu//bitstreams/77cf7fe6-4b32-4959-a4a4-291fdd560c5a/download | null | Fabricated parts are often represented as compact connected smooth 3-manifolds with
boundary, where the boundaries consist of compact smooth 2-manifolds. This class of mathematical
structures includes topological spaces with enclosed voids and tunnels. Useful information about these
structures are coded into level functions (Morse functions) which map points in the 3-manifold onto their
height above a fixed plane. By definition, Morse functions are smooth functions, all of whose critical
points are nondegenerate. This information is presented by the Reeb graph construction that develops a
topologically informative skeleton of the manifold whose nodes are the critical points of the Morse function
and whose edges are associated with the connected components between critical slices. This approach
accurately captures the SFF process: using a solid geometric model of the part, defining surface
boundaries; selecting a part orientation; forming planar slices, decomposing the solid into a sequence of
thin cross-sectional polyhedral layers; and then fabricating the part by producing the polyhedra by additive
manufacturing. This note will define a qualitative and combinatorial parametric engineering model of the
SFF part design process. The objects under study will be abstract simplicial complexes K with boundary
∂K. Systems of labeled 2-surfaces in K, called slices, will be associated with the cross-sectional polyhedral
layers. The labeled slices are mapped into a family of digraph automata, which, unlike cellular automata,
are defined not on regular lattices with simple connectivities (cells usually have either 4 or 8 cell
neighborhoods) but on unrestricted digraphs whose connectivities are irregular and more complicated. | null | null | null | null | null | null |
['Baumers, M.', 'Tuck, C.', 'Wildman, R.', 'Ashcroft, I.', 'Rosamond, E.', 'Hague, R.'] | 2021-10-06T22:42:17Z | 2021-10-06T22:42:17Z | 8/15/12 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88464', 'http://dx.doi.org/10.26153/tsw/15401'] | eng | 2012 International Solid Freeform Fabrication Symposium | Open | ['Additive Manufacturing', 'estimator', 'direct metal laser sintering', 'build-time', 'energy consumption', 'production cost'] | Combined Build-Time, Energy Consumption and Cost Estimation for Direct Metal Laser Sintering | Conference paper | https://repositories.lib.utexas.edu//bitstreams/312734ab-e18e-4ac0-acf5-501201223068/download | University of Texas at Austin | As a single-step process, Additive Manufacturing (AM) affords full measurability
with respect to process energy inputs and production cost. However, the parallel character of
AM (allowing the contemporaneous production of multiple parts) poses a number of problems
for the estimation of resource consumption. A novel combined estimator of build-time, energy
consumption and production cost is presented for the EOSINT M270 Direct Metal Laser
Sintering system. It is demonstrated that the quantity and variety of parts demanded and the
resulting ability to utilize the available machine capacity impact process efficiency, both in
energy and in financial terms. | null | null | null | null | null | null |
['Johnson, Blake', 'Allcorn, Eric', 'Baek, Min G.', 'Koo, Joseph H.'] | 2021-10-05T13:56:33Z | 2021-10-05T13:56:33Z | 2011 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88373', 'http://dx.doi.org/10.26153/tsw/15312'] | eng | 2011 International Solid Freeform Fabrication Symposium | Open | ['polyamide 11', 'nanocomposites', 'fire retardant', 'selective laser sintering', 'montmorillonite', 'carbon nanofiber'] | Combined Effects of Montmorillonite Clay, Carbon Nanofiber, and Fire Retardant on Mechanical and Flammability Properties of Polyamide 11 Nanocomposites | Conference paper | https://repositories.lib.utexas.edu//bitstreams/1154978e-0206-4357-8b2f-97f233fa509a/download | University of Texas at Austin | This paper is focused on the development of polyamide 11 (PA11) nanocomposites with
enhanced fire retardant (FR) properties for application in selective laser sintering (SLS). Test
specimens of PA11 containing various percentages of intumescent FR additive, montmorillonite
(MMT) clay, and carbon nanofiber (CNF) were prepared via the twin screw extrusion technique.
The combined effects of MMT clay, CNF, FR additives on the mechanical and flammability
properties of these PA11 nanocomposites are studied. Izod impact testing, tensile testing, and
SEM analysis of are used to characterize mechanical properties. UL-94 and SEM analysis of
char surfaces are used to characterize the flammability properties of these materials. Results are
analyzed to determine any synergistic effects among the additives to the material properties of
PA11. | null | null | null | null | null | null |
['Snyder, Jessica', 'Wang, Chengyang', 'Hamid, Qudus', 'Sun, Wei'] | 2021-10-05T14:36:31Z | 2021-10-05T14:36:31Z | 2011 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88381', 'http://dx.doi.org/10.26153/tsw/15320'] | eng | 2011 International Solid Freeform Fabrication Symposium | Open | ['additive manufacturing', 'cell-laden microfluidic device', 'SFF patterning', 'replica molding', 'polydimethylsiloxane'] | Combined SFF Patterning and Replica Molding for Microfabrication of Cell-Laden Microfluidic Device | Conference paper | https://repositories.lib.utexas.edu//bitstreams/2aace3ed-7ec9-4b5e-8983-b3d0734c97eb/download | University of Texas at Austin | We report on a novel technique using additive manufacturing to fabricate a cell-laden
polydimethylsiloxane (PDMS) microfluidic device by SFF processes and replica molding. We
demonstrate concept feasibility and present results using single and multiple layer patterns. 3-dimensional
channel architecture is achieved by CAD/CAM technology and tuning manufacturing process parameters.
Our microfluidic device is fabricated in two stages (1) print negative mold by thermal extrusion of
polycaprolactone (PCL) using layer-by-layer precision extrusion deposition then (2) casting PDMS. Cells
and matrix are selectively assembled inside microchannels using multi-nozzle printing to demonstrate
feasibility of chip as a culture environment. The objective of this work is to fabricate a cell-laden
microfluidic device by combined solid freeform patterning and replica molding with direct cell writing
into channels. This work has application as a 3D physiological model for in vitro pharmacokinetic study
in space environment in preparation for long term manned missions. | null | null | null | null | null | null |
['Perez, K. Blake', 'Williams, Christopher B.'] | 2021-10-12T18:44:40Z | 2021-10-12T18:44:40Z | 2013 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88716', 'http://dx.doi.org/10.26153/tsw/15650'] | eng | 2013 International Solid Freeform Fabrication Symposium | Open | ['direct write', 'Additive Manufacturing', 'conductive materials', 'manual material patterning', 'hybrid material patterning', 'native material patterning'] | Combining Additive Manufacturing and Direct Write for Integrated Electronics – A Review | Conference paper | https://repositories.lib.utexas.edu//bitstreams/ec1601d3-ff71-4c08-9cf6-f620ffdfd1fa/download | University of Texas at Austin | Direct write (DW) of conductive materials in the context of Additive Manufacturing (AM)
enables embedded electronics within fabricated parts. Previous works use manual, hybrid, and
native material patterning systems to deposit conductive materials in parts fabricated by different
AM technologies. This capability could eliminate cabled interconnects and redundant electronics
packaging, resulting in a significant reduction of mass and assembly complexity. In this paper, the
authors explore applications of DW of conductive traces in the context of AM, review prior work
in the integration, and analyze the technical roadblocks facing their hybridization. Barriers to
integrating the two technology classes include material, process, and post-process compatibilities. | null | null | null | null | null | null |
['Ariadi, Y.', 'Campbell, R.I.', 'Evans, M.A.', 'Graham, I.J.'] | 2021-10-05T18:54:47Z | 2021-10-05T18:54:47Z | 2012 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88407', 'http://dx.doi.org/10.26153/tsw/15346'] | eng | 2012 International Solid Freeform Fabrication Symposium | Open | ['Computer Aided Consumer Design', 'Additive Manufacturing', 'consumers', 'easy-to-use design tools'] | Combining Additive Manufacturing with Computer Aided Consumer Design | Conference paper | https://repositories.lib.utexas.edu//bitstreams/b8cba56f-e05c-43d2-888a-e865e77a7eb3/download | University of Texas at Austin | This paper reports an investigation into the potential for consumers designing and
manufacturing their own products using a combination of “Computer Aided Consumer Design”
(CaCODE) and Additive Manufacturing (AM). Recent developments in the field of AM (cheaper
machines and new materials) have led to renewed interest in the manufacture of customised
products and, more specifically, allowing consumers to create their own bespoke products.
However, a persistent weak link in this paradigm is the inability of most consumers to create 3D
models as an input for AM. Operating a conventional CAD system requires a lengthy period of
specialist training and is therefore not viable in this context. Consequently, easy-to-use 3D
design tools are needed to make AM more accessible to consumers. This research study
investigated the suitability of such a system for enabling consumers to design their own pens for
manufacture using AM. The investigation also explored the consumer acceptance of current AM
capabilities when used for the production of consumer products. The results showed that careful
attention must be paid to the specific needs of consumers, both in terms of their product
preferences and their ability to use software. These will be used to guide the design of future
CaCODE systems. | null | null | null | null | null | null |
['Deckers, T.', 'Wolf, F.', 'Foret, P.', 'Witt, G.', 'Kleszczynski, S.'] | 2024-03-26T20:35:04Z | 2024-03-26T20:35:04Z | 2023 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/124399', 'https://doi.org/10.26153/tsw/51007'] | en_US | 2023 International Solid Freeform Fabrication Symposium | Open | ['process monitoring', 'highspeed monitoring', 'thermal highspeed monitoring', 'process gas', 'helium', 'alloy 718'] | Comparative Analysis of Process Stability in PBF-LB/M: (Thermal) Highspeed Imaging vs. Melt Pool Monitoring using Novel Gas Mixtures | Conference paper | https://repositories.lib.utexas.edu//bitstreams/6a313098-efef-4826-9dcf-b5b8f7e8bf53/download | University of Texas at Austin | Powder bed fusion of metals using a laser beam (PBF-LB/M) is increasingly gaining
popularity in the industry. However, ensuring a consistent quality of parts processed by PBF-LB/M
is crucial to compete with established manufacturing processes. In-situ process monitoring
systems, such as coaxial melt pool monitoring (MPM), can contribute to this goal by minimizing
post-process quality control. Three monitoring systems, a commercially available MPM system,
an optical high-speed camera, and a thermal high-speed camera, were compared to identify process
phenomena. Secondly, the suitability of the MPM system for in-situ quality control was tested by
employing novel gas mixtures in the process. The mixtures include argon (Ar) with hydrogen (H2),
helium (He), and carbon dioxide (CO2). The first results showed the capabilities of the MPM
system to monitor relevant process anomalies. Also, the addition of He and H2 to the process gas
resulted in an improvement in the melt pool stability and a reduction of process by-products
compared to Ar. | null | null | null | null | null | null |
['Karasoglu, M.', 'Yasa, E.', 'Tan, E.', 'Yağmur, A.'] | 2021-12-06T23:05:57Z | 2021-12-06T23:05:57Z | 2021 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90709', 'http://dx.doi.org/10.26153/tsw/17628'] | eng | 2021 International Solid Freeform Fabrication Symposium | Open | ['laser powder bed fusion', 'L-PBF', 'electron powder bed fusion', 'E-PBF', 'heat treatment', 'microstructure'] | A Comparative and Experimental Study on the Effect of Heat Treatment Cycles for PBF Ti6Al4V | Conference paper | https://repositories.lib.utexas.edu//bitstreams/ee8c896f-f414-47c4-91e2-3f9feeb94617/download | University of Texas at Austin | Powder bed fusion (PBF) presents the highest level of technological maturity and
industrialization level for metallic materials among other Additive Manufacturing technologies.
The advantages of high geometrical complexity, ability to produce internal cavities, reduced lead
time and buy-to-fly ratio enables a wide range of application areas from aerospace to biomedical.
Laser-PBF and Electron-PBF present different limitations and opportunities while they can both
build from Ti6Al4V powder. The performance of the E-PBF and L-PBF parts highly depends on
the resulting microstructures and differs significantly due to various mechanisms such as
preheating temperatures and processing environment. Moreover, the obtained material properties
generally necessitate heat treatments for reducing residual stresses, enhancing mechanical
properties and changing the microstructure. This study aims to investigate the effect of the same
heat treatment cycles on the E-PBF and L-PBF microstructure evolution and microhardness by a
comparative experimental work with several combinations of exposure durations, temperatures
and cooling rates. | null | null | null | null | null | null |
['Previtali, B.', 'Demir, A.G.', 'Bucconi, M.', 'Crosato, A.', 'Penasa, M.'] | 2021-11-08T23:22:06Z | 2021-11-08T23:22:06Z | 2017 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90073', 'http://dx.doi.org/10.26153/tsw/16994'] | eng | 2017 International Solid Freeform Fabrication Symposium | Open | ['economic feasibility', 'manufacturing costs', 'selective laser melting', 'tube-forming tools', 'tube bending'] | Comparative Costs of Additive Manufacturing vs. Machining: The Case Study of the Production of Forming Dies for Tube Bending | Conference paper | https://repositories.lib.utexas.edu//bitstreams/b75df0a0-ce21-486f-915f-fc795bd7b1b1/download | University of Texas at Austin | Additive manufacturing processes for metallic components become economically viable
when they substitute conventional processes that make use of moulds and dies to produce casting
or semi-finished parts with high added value. Common examples are: i) components in aerospace
or energy sectors obtained by investment casting in high-temperature alloys; ii) personalized
prostheses and implants in biocompatible metals in the biomedical sector. In both cases, the annual
batch size is low and often limited to a single or few pieces. However, for many other sectors
decision making for process substitution from conventional to AM processes requires a correct
economic analysis. The cost of AM processes depends also on the use of technological advantages.
The paper explores the economic feasibility of selective laser melting (SLM) process when
producing tube-forming tools. The analysed industrial case addresses the whole annual production
of bending tools, traditionally made by milling from a solid block. The aim of this work is to
identify the levers of the process that make additive production advantageous, even in more
traditional sectors like tooling when different tool materials are used (namely a tool steel and a
bronze alloy) and when hybrid manufacturing (subtractive plus additive) is carried out. | null | null | null | null | null | null |
['Telenko, Cassandra', 'Seepersad, Carolyn Conner'] | 2021-10-04T20:20:55Z | 2021-10-04T20:20:55Z | 2011 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88337', 'http://dx.doi.org/10.26153/tsw/15276'] | eng | 2011 International Solid Freeform Fabrication Symposium | Open | ['additive manufacturing', 'selective laser sintering', 'injection molding', 'nylon parts', 'energy consumption'] | A Comparative Evaluation of Energy Consumption of Selective Laser Sintering and Injection Molding of Nylon Parts | Conference paper | https://repositories.lib.utexas.edu//bitstreams/a262688a-d650-41ad-94b0-2196eb237b55/download | University of Texas at Austin | Additive manufacturing is often advocated as a sustainable alternative to competing
manufacturing technologies. This research study focuses on estimating and comparing the
energy consumption required for different production volumes of nylon parts using either
selective laser sintering (SLS) or injection molding (IM). For IM & SLS, energy consumption is
estimated for nylon material refinement and part fabrication. For IM, energy consumption is also
estimated for manufacturing the injection molds and refining their metal feedstock. A paintball
gun handle serves as a representative part for calculating and normalizing material flows and
processing times. For different sets of assumptions, cross-over production volumes are
calculated, at which the per-part energy consumption of the two processes is equivalent. These
energy-based cross-over production volumes are compared to similar economic cross-over
production volumes available in the literature. | null | null | null | null | null | null |
['Aremu, A.O.', 'Maskery, I.', 'Tuck, C.', 'Ashcroft, I.A.', 'Wildman, R.D.', 'Hague, R.I.M.'] | 2021-10-18T22:28:07Z | 2021-10-18T22:28:07Z | 2014 | Mechanical Engineering | null | https://hdl.handle.net/2152/89271 | eng | 2014 International Solid Freeform Fabrication Symposium | Open | ['selective laser melting', 'cubic unit cells', 'metal lattice structures'] | A Comparative Finite Element Study of Cubic Unit Cells for Selective Laser Melting | Conference paper | https://repositories.lib.utexas.edu//bitstreams/6b37e57f-c046-47b6-a4b4-8c17d988b3a1/download | University of Texas at Austin | Selective laser melting (SLM) enables the utilization of complicated lattice structures
in metallic components. To exploit this capability, it is important to understand the structural properties of these lattices. Topological variations in lattices are diverse, however,
only a few are suitable for SLM since some lattices require supports during manufacture
while others self-support. Difficulties associated with the removal of these supports and
their detrimental effects on surface finish makes the latter group better suited for SLM.
In this work, we investigate the structural properties of some self-supporting unit cells
via a finite element study and show that the performance of a lattice structure is largely
dependent on the topology of the unit cell. Variants of the gyroid and face centred cubic
unit cells performed better than body centred cubic cells. This was also observed when
lattices, made of repeating unit cells were compared. | null | null | null | null | null | null |
['Nouri, H.', 'Khoshnevis, B.'] | 2021-11-11T15:35:37Z | 2021-11-11T15:35:37Z | 2018 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90222', 'http://dx.doi.org/10.26153/tsw/17143'] | eng | 2018 International Solid Freeform Fabrication Symposium | Open | ['sintering methods', '3D printing', 'selective separation shaping', 'SSS', 'polymer'] | A Comparative Investigation of Sintering Methods for Polymer 3D Printing Using Selective Separation Shaping (SSS) | Conference paper | https://repositories.lib.utexas.edu//bitstreams/5d205e19-4025-442d-8ce8-0c247c2e0fc0/download | University of Texas at Austin | Selective Separating Shaping (SSS) is a novel additive manufacturing process which is capable of
processing polymeric, metallic, ceramic and cementitious materials. In earlier experiments, the capabilities of
SSS in fabrication of metallic, ceramic, cement-based and polymeric parts have been demonstrated. The focus of
this research has been on exploration of sintering methods in SSS for successful fabrication of polymeric parts.
The SSS machine has been used to build specimens made of polyamide (PA6) material. Bonds between layers
under two different thermal sintering methods are investigated to achieve better control over shrinkage and
maintain effective binding between layers. ImageJ platform and binary surface plots have been used for image
processing and evaluating final porosity under each heating mechanism. Further investigations are carried out on
properties of the base materials and the choice of sintering mechanism to further improve resolution of final parts. | null | null | null | null | null | null |
['Kaill, N.', 'Campbell, R.I.', 'Pradel, P.', 'Bingham, G.A.'] | 2021-11-30T19:27:50Z | 2021-11-30T19:27:50Z | 2019 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90521', 'http://dx.doi.org/10.26153/tsw/17440'] | eng | 2019 International Solid Freeform Fabrication Symposium | Open | ['material extrusion', '3-axis', '5-axis', 'anisotropic behavior', 'compressive loading', 'additive manufacturing'] | A Comparative Study Between 3-Axis and 5-Axis Additively Manufactured Samples and their Ability to Resist Compressive Loading | Conference paper | https://repositories.lib.utexas.edu//bitstreams/bb248f9c-3845-4fad-9be7-1957550ffa9b/download | University of Texas at Austin | One of the main limitations of parts made with Material Extrusion (ME) is their
anisotropic mechanical behaviour. This behaviour limits the functionality of these components
in multi-directional loading conditions. A critical factor for this mechanical behaviour is the
poor bonding between layers. 5-axis ME has the capability to orientate the printed layers in
order to limit the effect of poor inter-laminar bonding. Previous studies have investigated 5-
axis ME, but not fully explored 5-axis capabilities of this manufacturing technique. To address
this gap, this paper compares the mechanical behaviour of 3-axis and 5-axis ME samples when
subjected to compressive loading. The results demonstrate how depositing material in “3D
layers” can improve the consistency of a sample’s mechanical behaviour. This study indicates
that 5-axis ME can enable more isotropic behaviour in printed samples. | null | null | null | null | null | null |
['Shanmugam, Ragavanantham', 'Chandran, Jishu', 'Vinayagam, Mohanavel', 'Fakron, Osama', 'Dennison, Seth', 'Romine, Seth'] | 2023-02-10T14:04:31Z | 2023-02-10T14:04:31Z | 2022 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/117449', 'http://dx.doi.org/10.26153/tsw/44330'] | eng | 2022 International Solid Freeform Fabrication Symposium | Open | ['Direct energy deposition (DED)', 'AlSi12 alloy', 'Pressure die casting', 'ultimate tensile strength', 'hardness', 'building directions'] | Comparative Study of Mechanical Properties of Aluminum Alloy A356 (Al-12Si) Fabricated by Directed Energy | Conference paper | https://repositories.lib.utexas.edu//bitstreams/0afe4fa9-8da4-422a-ae9e-faaf67c2e145/download | null | Additive Manufacturing technology is rapidly gaining traction in many manufacturing
applications due to its process parameters control and wide range of applications. There are
other AM technologies accessible, however Direct energy deposition (DED) is a critical
approach in metal matrix additive manufacturing. The significant two mechanical properties
tensile strength and hardness of additively created Al-12Si Aluminum alloy by DED process
and pressure die casted Al-12Si components are compared in this study. The strength and
modulus of the DED and PDC manufactured components were identical if the load direction
in the UTM machine was the same as the construction directions, however other mechanical
parameters differed slightly. Mechanical qualities of fabricated products made from reused
powders were also comparable to those made from unused powder. | null | null | null | null | null | null |
['Baumers, M.', 'Tuck, C.', 'Hague, R.', 'Ashcroft, I.', 'Wildman, R.'] | 2021-09-30T14:33:05Z | 2021-09-30T14:33:05Z | 9/23/10 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88257', 'http://dx.doi.org/10.26153/tsw/15198'] | eng | 2010 International Solid Freeform Fabrication Symposium | Open | ['metallic Additive Manufacturing', 'selective laser melting', 'electron beam melting', 'electricity consumption', 'process efficiency'] | A Comparative Study of Metallic Additive Manufacturing Power Consumption | Conference paper | https://repositories.lib.utexas.edu//bitstreams/94e9d739-bf06-4d58-a1c3-2755b00101b3/download | University of Texas at Austin | Efficient resource utilisation is seen as one of the advantages of Additive
Manufacturing (AM). This paper presents a comparative assessment of electricity
consumption of two major metallic AM processes, selective laser melting and electron beam
melting. The experiments performed for this study are based on the production of a common
power monitoring geometry. Due to the technology’s parallel nature, the degree of build
volume utilization will affect any power consumption metric. Therefore, this work explores
energy consumption on the basis of whole builds - while compensating for discrepancies in
packing efficiency. This provides insight not only into absolute levels of power consumption
but also on comparative process efficiency. | null | null | null | null | null | null |
['Nezhadfar, P.D.', 'Gradl, Paul R.', 'Shao, Shuai', 'Shamsaei, Nima'] | 2021-12-06T22:14:51Z | 2021-12-06T22:14:51Z | 2021 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90694', 'http://dx.doi.org/10.26153/tsw/17613'] | eng | 2021 International Solid Freeform Fabrication Symposium | Open | ['laser powder directed energy deposition', 'LP-DED', 'laser powder bed fusion', 'L-PBF', 'stainless steel', 'microstructure', 'texture'] | A Comparative Study on the Microstructure and Texture Evolution of L-PBF and LP-DED 17-4 PH Stainless Steel during Heat Treatment | Conference paper | https://repositories.lib.utexas.edu//bitstreams/0f07a342-a034-4276-9f7b-0d3d21e66740/download | University of Texas at Austin | This study aims to characterize the microstructure and crystallographic texture of 17-4
PH stainless steel (SS) manufactured with laser powder directed energy deposition (LP-DED)
and laser powder bed fusion (L-PBF), in both non-heat treated and heat treated conditions. It is
found that the non-heat treated LP-DED 17-4 PH SS possesses coarse columnar ferrite grains
decorated with Widmanstätten ferrite grains, whereas the L-PBF counterpart has very fine and
mostly equiaxed ferrite grains along with lath martensite. An identical stress relief (SR)
temperature is obtained for both the L-PBF and LP-DED 17-4 PH SS samples based on the
phase diagrams generated using Thermo-Calc. software. The SR step prior to CA-H1025 heat
treatment resulted in texture weakening and slightly refined the grain structure. The non-heat
treated L-PBF 17-4 PH SS sample possesses strong cube and γ-fiber textures, while the texture
transfers to weaker γ-fiber components after performing SR-CA-H1025 heat treatment. | null | null | null | null | null | null |
['Park, Sang-in', 'Rosen, David W.', 'Duty, Chad E.'] | 2021-10-19T15:19:45Z | 2021-10-19T15:19:45Z | 2014 | Mechanical Engineering | null | https://hdl.handle.net/2152/89296 | eng | 2014 International Solid Freeform Fabrication Symposium | Open | ['electron beam melting', 'lattice structures', 'lattice structure strength'] | Comparing Mechanical and Geometrical Properties of Lattice Structure Fabricated Using Electron Beam Melting | Conference paper | https://repositories.lib.utexas.edu//bitstreams/a1a05be3-a385-4163-b10c-6fff15b63c73/download | University of Texas at Austin | To design lattice structure, a uniform voxel based approach is widely used which divides
a part into unit volumes (e.g., cubes) and maps lattice topology into those volumes. In contrast,
conformal lattice structures represent a second design method for constructing lattices in which
unit cells are constructed parallel to the surface to be reinforced and are deformed in a manner
that enables them to conform to the surface. In this paper, the strength of lattice structures
designed using these two methods (uniform voxel based and conformal) are compared based on
additive manufacturing (AM) process effects. For this purpose, spheres filled with three types of
lattice structure are fabricated using electron beam melting technology and tested in compression.
Effects of AM processes are studied in two ways – volumetric and structural performance
equivalence. Struts in lattice structures are observed through a microscope to examine volume-equivalence and tests are simulated numerically and compared to identify structural equivalence. | null | null | null | null | null | null |
['Fulcher, Benjamin A.', 'Leigh, David K.', 'Watt, Trevor J.'] | 2021-10-12T22:46:58Z | 2021-10-12T22:46:58Z | 2014 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88761', 'http://dx.doi.org/10.26153/tsw/15695'] | eng | 2014 International Solid Freeform Fabrication Symposium | Open | ['Direct Metal Laser Sintering', 'aluminum alloys', 'AlSi10Mg', 'Al 6061', 'coefficient of thermal expansion'] | Comparison of AlSi10Mg and Al 6061 Processed through DMLS | Conference paper | https://repositories.lib.utexas.edu//bitstreams/d01d125d-ebe1-4cab-91c1-d1e084bf0bd5/download | University of Texas at Austin | Direct Metal Laser Sintering (DMLS) processing of aluminum alloys has been primarily
limited to a casting grade of aluminum, AlSi10Mg. The reasons for the choice of AlSi10Mg by
machine manufacturers are presently unknown; however, it is suspected that the reduced
coefficient of thermal expansion (CTE) due to the presence of Silicon may enhance DMLS
processability. Aluminum 6061 (Al 6061) is a commonly used alloy across a wide range of
industries and applications, and Harvest has observed a high interest in DMLS-manufactured
Al 6061 products. However, the higher CTE value potentially presents greater challenges in
controlling the shrinkage-induced warp common during DMLS. The work presented in this
paper was performed in an effort to understand differences in manufacturability as well as
mechanical properties of DMLS-processed AlSi10Mg and Al 6061. | null | null | null | null | null | null |
['Snelling, Dean', 'Williams, Christopher', 'Druschitz, Alan'] | 2021-10-12T21:23:57Z | 2021-10-12T21:23:57Z | 2014 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88743', 'http://dx.doi.org/10.26153/tsw/15677'] | eng | 2014 International Solid Freeform Fabrication Symposium | Open | ['binder jetting', 'sand molds', 'binder burnout', 'tensile strength', '3D printing'] | A Comparison of Binder Burnout and Mechanical Characteristics of Printed and Chemically Bonded Sand Molds | Conference paper | https://repositories.lib.utexas.edu//bitstreams/8a66a255-7746-4041-955c-ae0338c7929e/download | University of Texas at Austin | Various material systems have been created for Binder Jetting of sand molds; however, a
formal analysis comparing the materials to commonly used foundry molding materials has not
been conducted. In this paper the authors investigate potential differences in the material
properties from four different commercially available binders systems for chemically bonded
sand molds. Specifically, the authors compared the binder burnout characteristics and the tensile
strength of sand created by 3D printing and conventional chemically bonded molding materials.
Increased binder content can strengthen the mold but have adverse effect on part quality.
Understanding the binder characteristics of printed molds are essential due to the potential
defects from large amounts of gas generated from binder while pouring molten metal. | null | null | null | null | null | null |
['Hecker, F.', 'Driediger, C.', 'Hirsch, A.', 'Moritzer, E.'] | 2021-12-01T23:35:48Z | 2021-12-01T23:35:48Z | 2021 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90658', 'http://dx.doi.org/10.26153/tsw/17577'] | eng | 2021 International Solid Freeform Fabrication Symposium | Open | ['arburg plastic freeforming', 'fused deposition modeling', 'economic efficiency', 'process', 'comparison'] | Comparison of Component Properties and Economic Efficiency of the Arburg Plastic Freeforming and Fused Deposition Modeling | Conference paper | https://repositories.lib.utexas.edu//bitstreams/f4380083-3ea0-4be0-a148-a74fb0c32468/download | University of Texas at Austin | The additive manufacturing process Fused Deposition Modeling (FDM) is established
in the industry for many years. A new, similar process to FDM is the Arburg Plastic
Freeforming (APF). The main differences between both processes are the form of the starting
material (FDM: Filaments, APF: Conventional granulate) and the material deposition during
the layer formation (FDM: Melt strand, APF: fine molten droplets).
Since the two processes can be used in similar applications, the aim of this study is to
compare both processes in a holistic way. Furthermore, the advantages and disadvantages of
the processes are to be highlighted. The systematic comparison between a Stratasys 400mc and
the Freeformer 200-3X is divided into the areas of component properties, design limitations and
economic efficiency. The material ABS-M30 (Stratasys) is used in both processes. The results
show comparable component properties regarding mechanical and optical properties but also
differences in design limitations and cost efficiency. | null | null | null | null | null | null |
['Taghipour, Ehsan', 'Leu, Ming C.', 'Guo, Nannan'] | 2021-10-05T18:51:14Z | 2021-10-05T18:51:14Z | 8/18/12 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88406', 'http://dx.doi.org/10.26153/tsw/15345'] | eng | 2012 International Solid Freeform Fabrication Symposium | Open | ['bipolar plates', 'graphite-carbon-polymer composite compression molding', 'Selective Laser Sintering'] | Comparison of Compression Molding and Selective Laser Sintering Processes in the Development of Composite Bipolar Plates for Proton Exchange Membrane Fuel Cells | Conference paper | https://repositories.lib.utexas.edu//bitstreams/bf4c0f55-6b4e-4f13-8dda-a0193c8bcded/download | University of Texas at Austin | Bipolar plates are key components of Proton Exchange Membrane (PEM) fuel cells. They carry
current away from the cell and withstand the clamping force of the stack assembly. Therefore,
PEM fuel cell bipolar plates must have high electrical conductivity and adequate mechanical
strength, in addition to being light weight and low cost in terms of both applicable materials and
production methods. In order to attain these goals, we have manufactured graphite-carbon-polymer composite plates using Compression Molding (CM), which is suitable for mass
production, and Selective Laser Sintering (SLS), which is suitable for making prototypes. In this
paper, the electrical conductivity and flexural strength of the bipolar plates fabricated using the
CM process versus constitutive materials are experimentally studied. The properties of bipolar
plates fabricated using the CM process are compared with those of plates fabricated using the
SLS process. Natural graphite (NG), synthetic graphite (SG), carbon black (CB), and carbon
fiber (CF) are used as the constitutive materials for both processes, with epoxy resin employed as
the binder matrix. By varying the volume fraction of each constituent, the distribution of the
electrical conductivity and flexural strength of parts made using the CM and SLS processes are
obtained, and the similarities and differences of the effects of the various constituents between
these two processes are compared. | null | null | null | null | null | null |
['Spierings, A.B.', 'Levy, G.'] | 2021-09-28T20:14:52Z | 2021-09-28T20:14:52Z | 9/15/09 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88172', 'http://dx.doi.org/10.26153/tsw/15113'] | eng | 2009 International Solid Freeform Fabrication Symposium | Open | ['Selective Laser Melting', 'additive manufacturing', 'density measurement', 'Stainless Steel 316L parts', 'powder grades'] | Comparison of Density of Stainless Steel 316L Parts Produced with Selective Laser Melting using Different Powder Grades | Conference paper | https://repositories.lib.utexas.edu//bitstreams/e5dd3f6e-d0e2-48f2-b716-59d3b9b1fb84/download | University of Texas at Austin | Selective Laser Melting is a powder based additive manufacturing process where the metallic
powder particles are fused to 3D parts using a high energy laser beam. Much work has already
been conducted to investigate the details of the process, suitable materials and process parameters
and further more. As metallic powders are the raw material for this process, there are still a lot of
open questions relating to suitable grain size distributions for dense parts with regard to
productivity, surface quality, mechanical strength and ductility. The present work shows the
results of density measurements of parts, produced using three different particle size distributions
and different energy densities of the laser beam. Two layer thicknesses of 30μm and 45μm were
investigated.
It is shown that without a minimal amount of fine grains, which are able to fill the voids between
the coarse grains, lower scan speeds are needed in order to produce dense parts. Furthermore, the
differences in the relation of the powders to the densities, the layer thicknesses and laser scan
speeds indicate, that the powder grain size distribution plays an important role and that should be
taken into account for optimal results. This work is a contribution to the ASTM initiative F42 for
“Additive Manufacturing”. | null | null | null | null | null | null |
['Parvez, M.M.', 'Chen, Y.', 'Newkirk, J.W.', 'Liou, F.F.'] | 2021-11-17T23:35:33Z | 2021-11-17T23:35:33Z | 2019 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90355', 'http://dx.doi.org/10.26153/tsw/17276'] | eng | 2019 International Solid Freeform Fabrication Symposium | Open | ['fatigue test', 'fatigue performance', '304L', 'stainless steel', 'wrought', 'additive manufacture'] | Comparison of Fatigue Performance Between Additively Manufactured and Wrought 304L Stainless Steel Using a Novel Fatigue Test Setup | Conference paper | https://repositories.lib.utexas.edu//bitstreams/c64ff25e-3cf9-44b1-95fd-e074ac6c5ebe/download | University of Texas at Austin | In this research, a novel adaptive controlled fatigue testing machine was designed
for bending type high cycle fatigue test. A unique dual gauge section Krouse type mini specimen
was designed for simply supported transverse bending. Displacement controlled fatigue tests were
implemented using an electromechanical actuator. The variation in the control signal and load
observed during the test provides unique insights into realizing the deterioration of the specimen
due to fatigue. These analyses were utilized to compare the fatigue performance of wrought and
additively manufactured 304L stainless steel. The influence of the build direction on fatigue
performance was also investigated by testing specimens with 0, 45, and 90 degrees build direction.
These comparisons were carried out at different levels of displacement amplitude. | null | null | null | null | null | null |
['Gibson, A.', 'Weaver, J.M.'] | 2023-03-30T16:20:38Z | 2023-03-30T16:20:38Z | 2022 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/117702', 'http://dx.doi.org/10.26153/tsw/44581'] | eng | 2022 International Solid Freeform Fabrication Symposium | Open | Additive manufacturing | A Comparison of Layer Deposition and Open Molding of PETG by Fused Pellet Fabrication in an Additive Manufacturing System | Conference paper | https://repositories.lib.utexas.edu//bitstreams/1615ba22-a9cd-4b13-813f-2d583e1ef09e/download | null | Additive manufacturing continues to offer new possibilities in both production and
economics. The industry has quickly adopted it to rapidly produce parts that would be difficult or
cost preventative otherwise. Recent innovation has expanded its capabilities, however there are
still significant limitations. Most AM processes are restricted by materials available, in producing
large parts, or by not achieving material deposition speeds to make certain products feasible. In
addition, tight tolerances for features and surfaces cannot be produced without substantial post
processing. High-speed Fused Pellet Fabrication (FPF) in combination with Hybrid Manufacturing
(HM) offers expanded capabilities as additive and subtractive process are used within the same
space. It also allows for a different kind of additive process where an open mold can be cut from
a substrate and then filled using the FPF process to fabricate parts without layers. This, in
combination with Large Area Additive Manufacturing (LAAM), enables parts that leverage the
strengths of new and traditional methods at scales and speeds previously unavailable. | null | null | null | null | null | null |
['Alptug Tanrikulu, Ahmet', 'Ganesh-Ram, Aditya', 'Farhang, Behzad', 'Amerinatanzi, Amirhesam'] | 2024-03-25T23:29:06Z | 2024-03-25T23:29:06Z | 2023 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/124336', 'https://doi.org/10.26153/tsw/50944'] | en_US | 2023 International Solid Freeform Fabrication Symposium | Open | ['laser powder bed fusion', 'Ti6Al4V', 'preheating scan', 'post-heating scan', 'microstructure'] | Comparison of Layerwise Preheating and Post-heating Laser Scan on The Microstructure and Mechanical Properties of L-PBF Ti6Al4V | Conference paper | https://repositories.lib.utexas.edu//bitstreams/1b8d491a-35e0-4b45-a742-39fd7198cd6c/download | University of Texas at Austin | This study aimed to investigate the evolution of the microstructure and mechanical properties of asfabricated laser powder bed fusion (L-PBF) Ti-6Al-4V samples by introducing layerwise pre-heating or
post-heating laser scans. Multiple laser scans, varying in scanning speed at constant power, were examined
before the melting laser scan (pre-heating) or after it (post-heating). The analysis focused on microstructural
features such as porosity, and α-phases lath structure, as well as the hardness response of the material. The
results revealed the additional layerwise scans had a significant impact on reducing porosity by up to 98%
when the additional scan was applied prior to or upon the melting scan. Additional laser scans decreased
the microstructure and mechanical response variation along different orientations. Furthermore, these
findings highlight the potential of layerwise heating strategies to improve the overall quality and
performance of L-PBF Ti-6Al-4V components, thus paving the way for enhanced applications in various
industries such as aerospace. | null | null | null | null | null | null |
['Silverman, T. J.', 'Hall, A.', 'South, B.', 'Yong, W.', 'Koo, J. H.'] | 2020-03-10T14:18:01Z | 2020-03-10T14:18:01Z | 2007 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/80207', 'http://dx.doi.org/10.26153/tsw/7226'] | eng | 2007 International Solid Freeform Fabrication Symposium | Open | Selective Laser Sintering | Comparison of Material Properties and Microstructure of Specimens Built Using the 3D Systems Vanguard HS and Vanguard HiQ+HSSLS Systems | Conference paper | https://repositories.lib.utexas.edu//bitstreams/1ccc9aca-466f-4d1a-be01-7b3018ac6d44/download | null | The HiQ upgrade to the 3D Systems Vanguard selective laser sintering (SLS) machine incorporates a revised thermal calibration system and new control software. The paper compares
the tensile modulus, tensile strength, elongation at break, flexural modulus, Izod impact resistance and microstructure of two batteries of standard specimens built from recycled Duraform
PA (Nylon 12). The first set is built on a Vanguard HS system and the second on the same
system with the HiQ upgrade installed. The upgrade reduces user intervention, decreases total build time and improves surface finish. However, using the default processing parameters,
tensile, flexure and impact properties are all found to decline after the upgrade is installed. | null | null | null | null | null | null |
['Gaytan, S.M.', 'Murr, L.E.', 'Martinez, E.', 'Martinez, J.L.', 'Machado, B.I.', 'Ramirez, D.A.', 'Medina, F.', 'Collins, S.', 'Wicker, R.B.'] | 2021-09-30T14:44:02Z | 2021-09-30T14:44:02Z | 9/23/10 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88259', 'http://dx.doi.org/10.26153/tsw/15200'] | eng | 2010 International Solid Freeform Fabrication Symposium | Open | ['electron beam melting', 'cobalt powder', 'cobalt-based alloy components', 'microstructures', 'mechanical properties', 'femoral implant prototype'] | Comparison of Microstructures and Mechanical Properties for Solid Cobalt-Base Alloy Components and Biomedical Implant Prototypes Fabricated by Electron Beam Melting | Conference paper | https://repositories.lib.utexas.edu//bitstreams/18363426-9113-4471-ba6f-98c8089c6ed5/download | University of Texas at Austin | The microstructures and mechanical behavior of simple, as-fabricated, solid
geometries (with a density of 8.4 g/cm3), as-fabricated and fabricated and annealed
femoral (knee) prototypes all produced by additive manufacturing (AM) using electron
beam melting (EBM) of Co-26Cr-6Mo-0.2C powder are examined and compared in this
study. Microstructures and microstructural issues are examined by optical metallography,
SEM, TEM, EDS, and XRD while mechanical properties included selective specimen
tensile testing and Vickers microindentation (HV) and Rockwell C-scale (HRC) hardness
measurements. Orthogonal (X-Y) melt scanning of the electron beam during AM
produced unique, orthogonal and related Cr23C6 carbide (precipitate) cellular arrays with
dimensions of ~2μm in the build plane perpendicular to the build direction, while
connected carbide columns were formed in the vertical plane, parallel to the build
direction. | null | null | null | null | null | null |
['Sharma, Raghav', 'Le, Thao', 'Song, Jiaxu', 'Harms, Ethaniel', 'Sowa, Daniel', 'Grishin, Alex', 'Bhate, Dhruv'] | 2021-11-09T20:24:44Z | 2021-11-09T20:24:44Z | 2018 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90157', 'http://dx.doi.org/10.26153/tsw/17078'] | eng | 2018 International Solid Freeform Fabrication Symposium | Open | ['modeling', 'elastic behavior', 'plastic behavior', 'honeycomb structures', 'fused deposition modeling', 'additive manufacturing', 'FEA'] | A Comparison of Modeling Methods for Predicting the Elastic-Plastic Response of Additively Manufactured Honeycomb Structures | Conference paper | https://repositories.lib.utexas.edu//bitstreams/2ed739cd-e7ca-41c0-ad72-3c5e35566e39/download | University of Texas at Austin | Valid and accurate models describing the mechanical behavior of additively manufactured
cellular materials are crucial to enabling their implementation in critical-to-function parts. Broadly
speaking, the modeling approaches commonly used in the literature fall into three categories. Each
of these differs in the level of discretization at which the cellular behavior is modeled: at the level
of each material point, at the level of the unit cell or at the level of a connecting member that
constitutes a unit cell. Each of these three approaches relies on different characterization
techniques and the way in which the resulting data is leveraged in the development of the model.
In this work, we critically examine all three modeling approaches using FEA and compare their
accuracy in the prediction of the elastic and plastic behavior of experimentally characterized
hexagonal honeycomb structures made with Fused Deposition Modeling, and discuss the pros and
cons of each method. | null | null | null | null | null | null |
['Diaz, J.', 'Caballero, K.', 'Medrano, V.A.', 'Arrieta, E.', 'Benedict, M.', 'Godfrey, D.', 'Wicker, R. B.', 'Medina, F.'] | 2023-03-29T16:31:36Z | 2023-03-29T16:31:36Z | 2022 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/117682', 'http://dx.doi.org/10.26153/tsw/44561'] | eng | 2022 International Solid Freeform Fabrication Symposium | Open | aluminum F357 | Comparison of Multiple Heat Treatments by Observing Mechanical Properties and Microstructure of LPBF Fabricated Aluminum F357 | Conference paper | https://repositories.lib.utexas.edu//bitstreams/4ab3b9c1-50f1-457c-b359-8135936007c1/download | null | In this paper, Aluminum F357 (AlSi7Mg), a material which is widely used in the
automotive, aerospace, and additive manufacturing industries, will be analyzed after performing
several heat treatments to enhance the properties of the material. However, there is currently no
standard for the usage and heat treating of F357 alloy; for that reason, ASTM F3318 standard will
be followed for heat treating it. Having a comprehensive study on the performance of 3D-printed
F357 benefits the automotive, military and aerospace industries due to the numerous casted
components already in service and many becoming legacy components. This work presents
mechanical and microstructural properties of F357 specimens fabricated with SLM technology
and subjected to heat treatments; as-built, stress-relief, T6, hot isostatic pressing (HIP), and
HIP+T6 heat treatments were applied. Furthermore, with the interest of the alloy performance in-
service conditions, the specimens were subjected to artificial thermal aging. | null | null | null | null | null | null |
Leigh, David K. | 2021-10-06T20:40:10Z | 2021-10-06T20:40:10Z | 2012 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88438', 'http://dx.doi.org/10.26153/tsw/15375'] | eng | 2012 International Solid Freeform Fabrication Symposium | Open | ['laser sintering', 'compression molding', 'Polyamide-11', 'Ultimate Tensile Strength', 'Elongation at Break'] | A Comparison of Polyamide 11 Mechanical Properties Between Laser Sintering and Traditional Molding | Conference paper | https://repositories.lib.utexas.edu//bitstreams/9a419d0d-0d6f-4189-937f-d29e1e61ff5f/download | University of Texas at Austin | Tensile properties of laser sintering grade Polyamide-11 are processed using laser
sintering, compression molding, and injection molding and the resultant mechanical properties
are reported. The primary contributor to the enhanced mechanical properties of injection molded
specimens is a fully healed polymer melt with preferred polymer chain orientation. It can be
shown that laser sintering and compression molding specimens have comparable to compression
molding specimens Ultimate Tensile Strength (UTS) and Elongation at Break (EOB). | null | null | null | null | null | null |
['Ameen, Ahamed', 'Janik, Vit', 'Nicholas, Joanna', 'Zhang, Xiang', 'Seow, Cui Er'] | 2024-03-26T23:06:32Z | 2024-03-26T23:06:32Z | 2023 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/124441', 'https://doi.org/10.26153/tsw/51049'] | en_US | 2023 International Solid Freeform Fabrication Symposium | Open | ['wire-arc DED', 'low alloyed steel', 'interpass surface temperature', 'interpass dwell time', 'thermo-couple measurement'] | Comparison of process control methods for wire-arc directed energy deposition of low carbon steels with in-situ temperature measurement | Conference paper | https://repositories.lib.utexas.edu//bitstreams/53101007-760e-4895-9b96-46330227d74b/download | University of Texas at Austin | Additive manufacturing (AM) techniques enable the production of near-net shape parts.
Wire-arc direct energy deposition (WA-DED) can achieve a higher deposition rate among other
available metal AM methods. Conventional arc welding requires a maximum interpass
temperature to limit any reduction in mechanical properties, but this may not be practicable for
wWA-DED. In this study, two interpass process control methods, one with maximum interpass
surface temperature and the other with constant dwell time, were adopted to deposit low alloyed
steel walls while maintaining the same feedstock and heat input values. Thermocouples were
inserted at three different positions in the walls during deposition, to record the thermal
profiles. Test samples extracted from walls exhibited similar tensile strength (~10 MPa
difference) and hardness values. Microstructural evaluation showed the presence of interlayer
regions with alternating coarse and fine bands of ferrite grains, irrespective of the interpass
control method. These findings suggest that dwell time control is better for productivity. | null | null | null | null | null | null |