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['Bzymek, Zbigniew M.', 'Shaw, Leon L.', 'Marks, Wojciech'] | 2019-02-22T20:12:44Z | 2019-02-22T20:12:44Z | 1998 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/73474', 'http://dx.doi.org/10.26153/tsw/624'] | eng | 1998 International Solid Freeform Fabrication Symposium | Open | ['SFF', 'SALD'] | A Theoretical Model for Optimization of SALD Parameters | Conference paper | https://repositories.lib.utexas.edu//bitstreams/0dbcdd8e-189f-45a0-ad9c-2a9b333ba558/download | null | This paper addresses the need to conduct theoretical work concerning an economical way
of Solid Freeform Fabrication rendering by using selective Area Laser Deposition (SALD). The
part in SALD rendering process is formed layer by layer that, in turn, is composed of stripes of
material produced in the path of a laser. There are three situations in which such a stripe can be
rendered: a) alone, b) with one neighbor on one side, and c) with neighbors on both sides.
Residual thermal stresses in the part are expected to be affected by how a stripe is rendered.
Furthermore, the residual thermal stress and the mechanical property of the part are also dictated
by other processing variables such as laser scanning patters, laser input power, scanning speed,
scanning spacing, deposition temperature, gas precursor pressure, intrinsic thermal conductivity
and mechanical properties of the rendered material. A theoretical approach is proposed to address
the minimization of residual thermal stresses and rendering times and the maximization of the
strength of the part. It is proposed that such multiple optimizations that are dictated by many
decision variables can be solved by minimizing and/or maximizing object functions dePending on
the design criteria for each attribute of the rendered part | null | null | null | null | null | null |
['Wu, Tao', 'Das, Suman'] | 2021-10-06T21:25:02Z | 2021-10-06T21:25:02Z | 2012 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88449', 'http://dx.doi.org/10.26153/tsw/15386'] | eng | 2012 International Solid Freeform Fabrication Symposium | Open | ['large area maskless photopolymerization', 'part stresses', 'part warpage', 'crack development'] | Theoretical Modeling and Experimental Characterization of Stress Development in Parts Manufactured Through Large Area Maskless Photopolymerization | Conference paper | https://repositories.lib.utexas.edu//bitstreams/9ce4943a-aa1e-4fe2-8d22-df35f96df77d/download | University of Texas at Austin | This paper aims at investigating the evolution of stresses in parts manufactured through
large area maskless photopolymerization (LAMP). A theoretical model was established to
understand the curing process for LAMP and a finite element analysis was performed to model
the dynamic evolution of stresses during the layer-by-layer fabrication process using Abaqus
software. This model serves to suggest strategies for reducing stresses, part warpage, and crack
development in parts made through LAMP. | null | null | null | null | null | null |
['Wang, Yu', 'Chen, Ziqian', 'Li, Houqi', 'Li, Shuaishuai'] | 2021-11-15T21:48:05Z | 2021-11-15T21:48:05Z | 2018 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90281', 'http://dx.doi.org/10.26153/tsw/17202'] | eng | 2018 International Solid Freeform Fabrication Symposium | Open | ['additive manufacturing', 'material extrusion', 'mechanical performance', 'anisotropy', 'force-flow'] | Theory and Methodology for High-Performance Material-Extrusion Additive Manufacturing Under the Guidance of Force-Flow | Conference paper | https://repositories.lib.utexas.edu//bitstreams/bf11333b-d8f3-4ec2-8a2d-3c03dba5cb96/download | University of Texas at Austin | Anisotropy on strength between different layers and filaments in the material extrusion
(MEX) process has a significant influence on mechanical performances of fabricated objects. A
novel theory and methodology is proposed to improve mechanical performances of parts by
designing and controlling the anisotropy. Anisotropy can then be in alignment with load paths
under the guidance of force-flow. In this study, by (1) dividing the part into several building areas
and generating corresponding building direction considering the force-flow properties of the part;
(2) generating novel toolpaths which are based on principal stress lines (PSL) and will map the
direction and magnitude of PSL, the adverse influence of anisotropy on mechanical performances
between different layers and filaments can be minimized respectively. A 6-axis robot arm
integrated with an extrusion system is constructed to handle the multi-direction building of each
building area. The study will advance the development of additive manufacturing from "prototype"
to "end-use". | null | null | null | null | null | null |
['Maxwell, James L.', 'Pegna, Joseph'] | 2018-05-03T19:29:02Z | 2018-05-03T19:29:02Z | 1993 | Mechanical Engineering | doi:10.15781/T2DF6KM4K | http://hdl.handle.net/2152/65065 | eng | 1993 International Solid Freeform Fabrication Symposium | Open | ['LCVD', 'SALD', 'Microfrabrication', 'selective area laser deposition'] | Thermal Analysis and Modeling of Steady-State Rod Growth During Gas-Phase Solid Freeform Fabrication | Conference paper | https://repositories.lib.utexas.edu//bitstreams/1be7ec8c-00d4-4851-91af-c2756dea884b/download | null | An analysis ofthe steady-state growth ofrods during gas-phase solidfreeform fabrication
is presented. It is demonstrated that heat transfer controls the evolution ofshape during laser-induced
pyrolysis of slender 3-D structures. Insulating and conductive deposit materials were studied, using
both simple analytic and numerical simulations to demonstrate how steady-state rod growth is
achieved. | null | null | null | null | null | null |
['Mohammadizadeh, M.', 'Fidan, I.'] | 2021-11-18T02:00:30Z | 2021-11-18T02:00:30Z | 2019 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90405', 'http://dx.doi.org/10.26153/tsw/17326'] | eng | 2019 International Solid Freeform Fabrication Symposium | Open | ['additive manufacturing', 'fiber reinforcement', 'mechanical properties'] | Thermal Analysis of 3D Printed Continuous Fiber Reinforced Thermoplastic Polymers for Automotive Applications | Conference paper | https://repositories.lib.utexas.edu//bitstreams/fae3e550-7d1f-46ed-8e9b-c2a87ab2e073/download | University of Texas at Austin | Continuous fiber reinforced additive manufacturing (CFRAM) is a five-year old manufacturing
technology with a wide range of potential applications. CFRAM benefits from the advantages of
Fused Filament Fabrication as fast and low cost production of complicated structures, while fiber
reinforcement improves thermomechanical properties. CFRAM provides wide range of potential
applications in auto industry, aerospace, sport goods and medical tools to replace metals and
conventional composites with CFRAM parts. The notable attention toward CFRAM technology
justifies the need for investigation of thermomechanical properties of printed components. In this
study, CFRAM components were manufactured using Markforged 3D-printer. Nylon was used
as thermoplastic polymer matrix and carbon fiber (CF), fiber glass (FG), and Kevlar as
reinforcing agents. Thermo-Gravimetric Analysis (TGA), and Dynamic Mechanical Analysis
(DMA) measurements were conducted to investigate thermomechanical properties. The results
of this study will be a milestone for applications of CFRAM components for automotive
industry. | null | null | null | null | null | null |
['AtifYardimci, M.', 'Hattori, Takeshi', 'Guceri, Selcuk I.', 'Danforth, Stephen C.'] | 2018-12-07T16:28:14Z | 2018-12-07T16:28:14Z | 1997 | Mechanical Engineering | doi:10.15781/T2M61C92N | http://hdl.handle.net/2152/71449 | eng | 1997 International Solid Freeform Fabrication Symposium | Open | ['Fused Deposition process', 'discrete layers'] | Thermal Analysis Of Fused Deposition | Conference paper | https://repositories.lib.utexas.edu//bitstreams/0661da81-51b6-4b14-baf8-2a3f736eea27/download | null | Fused Deposition processes involve successive melting, extrusion and solidification of
thermoplastic polymer melts. Fluid mechanics and heat transfer of neat or particle-filled
polymeric melts, viscoelastic deformation and solidification ofthe roads that are being produced,
and repetitive thermal loading of the growing part are important physical processes that control
the final quality of the part. Previous computational process models investigated deposition and
cooling processes for single and multiple filaments. In the current study, complimentary
computational models are presented for the extrusion phase of the process. Impact of liquefier
and nozzle design on thermal hardware behavior and operational stability has been quantified.
Also a detailed study of temperature field near the vicinity of deposition point is presented with
particular emphasis on dimensional analysis and deposition ofmultiple material systems. | null | null | null | null | null | null |
['Billah, Kazi Md Masum', 'Lorenzana, Fernando A.R.', 'Martinez, Nikki L.', 'Chacon, Sarah', 'Wicker, Ryan B.', 'Espalin, David'] | 2021-11-18T01:58:51Z | 2021-11-18T01:58:51Z | 2019 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90404', 'http://dx.doi.org/10.26153/tsw/17325'] | eng | 2019 International Solid Freeform Fabrication Symposium | Open | ['thermal analysis', 'neat ABS', 'reinforced ABS', 'carbon fiber', 'thermoplastics', 'large area 3D printing'] | Thermal Analysis of Thermoplastic Materials Filled with Chopped Fiber for Large Area 3D Printing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/2ea51c57-2172-4142-9f4e-db2d1df20973/download | University of Texas at Austin | At room temperature, material extrusion, in the context of large area fabrication, requires
thermally stable materials and, as a result, fillers are included to tailor the thermal behavior. This
research investigated the thermophysical properties of neat ABS and short carbon fiber (CF)
reinforced ABS. Thermogravimetric analysis, differential scanning calorimetry, and
thermomechanical analysis were carried out to determine the thermophysical properties. The
addition of CF (20 wt. %) to an ABS matrix caused the glass transition temperature to change
slightly (110 °C to 105 °C). Also, the CF within the ABS matrix reduced the thermal stability by
decreasing the degradation on set temperature by (323 °C to 253 °C). Thermal deformation
analysis showed that large area pellet extruded AM machine produces highly anisotropic materials.
Thermomechanical analysis results showed that the coefficient of thermal expansion (CTE)
reduced 4 times in the perpendicular to the extruded direction. The dataset and knowledge from
the thermal analysis can be useful to design optimized printing parameters for highly filled
thermoplastics used in large area 3D printing machines. | null | null | null | null | null | null |
['Dai, K.', 'Shaw, L.'] | 2019-10-18T15:20:02Z | 2019-10-18T15:20:02Z | 2001 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/76236', 'http://dx.doi.org/10.26153/tsw/3325'] | eng | 2001 International Solid Freeform Fabrication Symposium | Open | Fabrication | Thermal and Stress Modeling of Laser Fabrication of Multiple Material Components | Conference paper | https://repositories.lib.utexas.edu//bitstreams/35f85c04-7e22-463a-8333-387636fda758/download | null | Solid freeform fabrication (SFF) is an automated manufacturing process that builds threedimensional complex-shaped structures layer-by-layer directly from CAD data without partspecific tooling and human intervention. In many cases multiple materials are involved in
fabricating one component using SFF approaches. Porcelain-fused-to-metal (PFM) restoration
for permanent fixed prosthodontics is an example of this kind. In this study 3-dimensional finite
element modeling has been carried out to investigate the temperature and stress field in
processing of multiple material components using a moving laser beam. Effects of fabrication
sequences, laser scanning patterns and scanning rates on residual stresses have been investigated.
Implications of these results on laser fabrication of multiple materials have been discussed. | null | null | null | null | null | null |
['Velu, Rajkumar', 'Singamneni, Sarat'] | 2021-10-21T21:58:09Z | 2021-10-21T21:58:09Z | 2015 | Mechanical Engineering | null | https://hdl.handle.net/2152/89453 | eng | 2015 International Solid Freeform Fabrication Symposium | Open | ['PMMA+β-TCP', 'biopolymer composites', 'selective laser sintering', 'thermal fields'] | Thermal Aspects of Selective Laser Sintering of PMMA+β-TCP Composites | Conference paper | https://repositories.lib.utexas.edu//bitstreams/b9280775-1222-47b3-8f22-c2707d782f57/download | University of Texas at Austin | Biocompatible and osteoconductive characteristics expected of materials used for bone grafting
applications identified Polymethyl methacrylate (PMMA) and β-Tri Calcium Phosphate (βTCP) combinations to be potential biopolymer composite options. Together with additive
manufacturing methods such as selective laser sintering (SLS), these materials options would
also bring about the benefits of free from fabrication. While earlier research laser sintering
PMMA+β-TCP composites experimentally proved the combination to be promising, the
resulting microstructures are indicative of varied coalescence and consolidation with varying
amounts of β-TCP. Considering the differential thermal properties, it becomes necessary and
interesting to evaluate the possible role of the filler material in altering the nature of the thermal
fields. This paper presents results of numerical and experimental work carried out investigating
the thermal fields of laser sintered PMMA+β-TCP composites. | null | null | null | null | null | null |
['Griffith, M.', 'Schlienger, M. E.', 'Harwell, L. D.', 'Oliver, M. S.', 'Baldwin, M. D.', 'Ensz, M. T.', 'Smugeresky, J. E.', 'Essien, M.', 'Brooks, J.', 'Robino, C. V.', 'Hofineister, W. H.', 'Wert, M. J.', 'Nelson, D. V.'] | 2019-02-19T17:22:15Z | 2019-02-19T17:22:15Z | 1998 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/73432', 'http://dx.doi.org/10.26153/tsw/584'] | eng | 1998 International Solid Freeform Fabrication Symposium | Open | ['H13 Tool Steel', 'LENS'] | Thermal Behavior in the Lens Process | Conference paper | https://repositories.lib.utexas.edu//bitstreams/6ee8ad82-ed3c-4639-b361-ea5d194e4458/download | null | Direct laser metal deposition processing is a promising manufacturing technology which
could significantly impact the length oftime between initial concept and finished part. For
adoption ofthis technology in the manufacturing environment, further understanding is required
to ensure robust components with appropriate properties are routinelyfabricated. This requires a
complete understanding ofthe thermal history.during part fabrication and control ofthis behavior.
This paper will describe our research to understand the thermal behavior for the Laser Engineered
Net Shaping (LENS) process!, where a component is fabricated by focusing a laser beam onto a
substrate to create a molten pool in which powder particles are simultaneously injected to build
each layer. The substrate is moved beneath the l~ser beam to deposit a thin cross section, thereby
creating the desired geometry for each layer. After deposition of each layer, the powder delivery
nozzle and focusing lens assembly is incremented in the positive Z-direction, thereby building a
three dimensional component layer additively.
It is important to control the thermal behavior to reproducibly fabricate parts. The
ultimate intent is to monitor the thermal signatures and to incorporate sensors and feedback
algorithms to control part fabrication. With appropriate control, the geometric properties
(accuracy, surface finish, low warpage) as well as the materials' properties (e.g. strength,
ductility) of a component can be dialed into the part through the fabrication parameters. Thermal
monitoring techniques will be described, and their particular benefits highlighted. Preliminary
details in correlating thermal behavior with processing results will be discussed. | null | null | null | null | null | null |
['Karapatis, N. P.', 'Guidoux, Y.', 'Gygax, P. E.', 'Glardon, R.'] | 2019-02-19T17:04:49Z | 2019-02-19T17:04:49Z | 1998 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/73431', 'http://dx.doi.org/10.26153/tsw/583'] | eng | 1998 International Solid Freeform Fabrication Symposium | Open | ['Selective Laser Sintering', 'metallic powders'] | Thermal Behavior of Parts Made by Direct Metal Laser Sintering | Conference paper | https://repositories.lib.utexas.edu//bitstreams/9ae91c4f-2259-4e0d-9aca-b2cc0ef4b381/download | null | The Direct Metal Laser Sintering (DMLS) manufacturing technique induces thermal stresses
in parts. When such parts are used at elevated temperatures, residual stresses are relaxed and the
part can suffer significant distortion. This study presents values of geometrical distortion for two
laser exposure strategies and for different heat treatment temperatures and durations. Surface and
bulk hardness data are provided as well as porosity measurements. At temperatures above 300
the geometrical changes become important. A stabilization treatment. at 600°C can help reduce
distortions. | null | null | null | null | null | null |
['Yuan, Mengqi', 'Bourell, David', 'Diller, Tim'] | 2021-10-05T13:28:24Z | 2021-10-05T13:28:24Z | 8/17/11 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88366', 'http://dx.doi.org/10.26153/tsw/15305'] | eng | 2011 International Solid Freeform Fabrication Symposium | Open | ['laser sintering', 'thermal conductivity', 'thermal diffusivity', 'polyamide 12'] | Thermal Conductivity Measurements of Polyamide 12 | Conference paper | https://repositories.lib.utexas.edu//bitstreams/a3fa6b85-1651-4dbc-8500-8487ab22823a/download | University of Texas at Austin | An important component in understanding the laser sintering process is knowledge of the
thermal properties of the processed material. Thermal conductivity measurements of pure
polyamide 12 were conducted based on transient plane source technology using a Hot Disk®
TPS500 conductivity measurement device. Polyamide samples were packed to three different
densities in nitrogen at steady state. Thermal diffusivity and conductivity were measured from
40°C to 170°C for both fresh powder and previously heated (“recycled”) powder. The fresh
powder tests revealed that thermal conductivity increased linearly with temperature while for
previously heated powder, more constant and higher thermal conductivity was observed as it
formed a powder cake. Tests were also performed on fully dense polyamide 12 to establish a
baseline. Polyamide 12 powder had a room-temperature thermal conductivity of
approximately 0.1 W/mK which increased with temperature, whereas the bulk laser sintered
polyamide 12 room-temperature value was 0.26 W/mK and generally decreased with
increasing temperature. | null | null | null | null | null | null |
['Orme, Melissa E.', 'Huang, Changzheng'] | 2018-10-04T20:35:09Z | 2018-10-04T20:35:09Z | 1995 | Mechanical Engineering | doi:10.15781/T2RX93Z5T | http://hdl.handle.net/2152/68710 | eng | 1995 International Solid Freeform Fabrication Symposium | Open | ['CAD', 'Solid free-form fabrication', 'metallic structural components'] | Thermal Design Parameters Critical to the Development of Solid Freeform Fabrication of Structural Materials with Controlled Nano-liter Droplets | Conference paper | https://repositories.lib.utexas.edu//bitstreams/5b38decf-ec13-4a77-a14b-6a28506a806c/download | null | null | null | null | null | null | null | null |
['Norrell, Jeffery L.', 'Wood, Kristin L.', 'Crawford, Richard H.'] | 2019-03-12T16:58:50Z | 2019-03-12T16:58:50Z | 1999 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/73603', 'http://dx.doi.org/10.26153/tsw/745'] | eng | 1999 International Solid Freeform Fabrication Symposium | Open | ['SLS', 'in-bed structures'] | Thermal Effects of In-Bed Rapid Prototyping Metastructures | Conference paper | https://repositories.lib.utexas.edu//bitstreams/4060cbc0-9615-4fe6-9acf-8623f708663b/download | null | Iuan effort. t.o produce higher quality Selective Laser Sint.ering (SLS) parts, a number of approaches
have been taken. One such approach is t.he use of in-bed·metastructures, such as tortillas and canist.ers. In past. work, these metast.ructures have produced changes part qualit.y, but only qualitative
analysis has been done. Using a model created during previous work, a numerical st.udy of these in-bed
metastructures is undertaken, with the goal of systematically determining the thermal effectiveness of the
various structures. The thermal behavior of in-bed st.ructures subjected t.o mixed mode convection and
conduction is then determined. Result.s demonstrate that in-bed structures can be designed t.o spatially
affectin-bed thermal transfer, providing SLS users t.he capability to remove or retain heat as a part's
local geometry demands. | null | null | null | null | null | null |
['Hopkinson, Neil', 'Dickens, Phill'] | 2018-11-30T15:29:29Z | 2018-11-30T15:29:29Z | 1997 | Mechanical Engineering | doi:10.15781/T2V40KK0V | http://hdl.handle.net/2152/70594 | eng | 1997 International Solid Freeform Fabrication Symposium | Open | ['3DKeltool', 'EDM'] | Thermal Effects on Accuracy in the 3DKeltool™ Process | Conference paper | https://repositories.lib.utexas.edu//bitstreams/f447be80-cc6b-46f5-a505-dd5c368dca94/download | null | The 3DKeltool™ process has been used to produce injection moulding inserts capable
ofproducing millions ofparts with quick cycle times (1). Short lead times are possible
however accuracy is reduced for dimensions over 150mm.
The use ofroom temperature vulcanising (RTV) silicone rubber in the 3DKeltool™
process is a possible reason for the loss of accuracy in larger parts. Effects of
temperature changes during the process are assessed both theoretically and
experimentally.
The results show close agreement between theoretical predictions and experimental
results for dimensional changes. Suggestions which could allow accurate manufacture
oflarger 3DKletool™ parts are presented. | null | null | null | null | null | null |
['Taylor, Samantha', 'Beaman, Joseph', 'Fish, Scott'] | 2021-11-04T13:36:02Z | 2021-11-04T13:36:02Z | 2017 | Mechanical Engineering | null | https://hdl.handle.net/2152/89955 | eng | 2017 International Solid Freeform Fabrication Symposium | Open | ['mechanical property', 'correlation', 'in-situ monitoring', 'thermal history', 'selective laser sintering'] | Thermal History Correlation with Mechanical Properties for Polymer Selective Laser Sintering (SLS) | Conference paper | https://repositories.lib.utexas.edu//bitstreams/b53aad8c-e440-4be6-9a6b-198a76398aed/download | University of Texas at Austin | This study investigates the in-situ monitoring of the Selective Laser Sintering (SLS)
process by focusing on finding correlations between tensile strength, elongation to break, and
fracture location to the observed thermal history of manufactured parts. It compared the
monitoring ability of a stationary reference mid-wave infrared and a bore-sighted mid-wave
infrared camera. ZYX tensile bars were built to leverage the high dependence of tensile strength
on interlayer bonding, which is generally assumed to be related to layerwise thermal conditions.
Various thermal history analysis methods, for example: cold subregion temperature, average
layer temperature, and outline average temperature were tested. Additionally, several smoothing
techniques that reduced noise over time were assessed for their ability to improve the correlation
for each individual method. Overall, cold subregions observed over four layers in a tensile bar’s
thermal history had the best correlation with fracture location and mechanical strength. | null | null | null | null | null | null |
['Flach, Lawrance', 'Klostennan, Donald A.', 'Chartoff, Richard P.'] | 2018-12-07T16:25:26Z | 2018-12-07T16:25:26Z | 1997 | Mechanical Engineering | doi:10.15781/T2QZ2336G | http://hdl.handle.net/2152/71448 | eng | 1997 International Solid Freeform Fabrication Symposium | Open | ['LOM', 'experimental materials'] | A Thermal Model For Laminated Object Manufacturing (LOM) | Conference paper | https://repositories.lib.utexas.edu//bitstreams/a5936987-0589-476c-b990-64086d3827aa/download | null | A thennal model for Laminated Object Manufacturing (LOM) has been developed. The
model is based on 3-dimensional transient heat conduction in a rectangular geometry LOM part.
Heat transfer from the heated roller to the laminated part as well as heat loss to the surroundings
and the base plate are considered. It allows calculation of the transient temperature distribution
within the part during the application of a new layer as well as during other periods of the LOM
build cycle. To verify the model performance, thennocouples were embedded every 4th layer in a
20-layer ceramic part while it was being built on a standard LOM-2030. The model predictions are
in excellent agreement with the measured temperature profiles. In addition to explaining the
observed thennal behavior ofLOM parts, model predictions also have direct application to on-line
control ofthe part temperature during the build process, to be discussed herein. | null | null | null | null | null | null |
['Diller, Timothy T.', 'Sreenivasan, Rameshwar', 'Beaman, Joseph', 'Bourell, David', 'LaRocco, Janna'] | 2021-09-30T18:50:39Z | 2021-09-30T18:50:39Z | 2010 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88277', 'http://dx.doi.org/10.26153/tsw/15218'] | eng | 2010 International Solid Freeform Fabrication Symposium | Open | ['thermal control', 'selective laser sintering', 'surface finish', 'nylon parts', 'polyamide parts', 'thermal diffusivity'] | Thermal Model of the Build Environment for Polyamide Powder Selective Laser Sintering | Conference paper | https://repositories.lib.utexas.edu//bitstreams/7c9fd931-5afb-410f-ac8a-6246340a65ca/download | University of Texas at Austin | Precise thermal control of selective laser sintering
(SLS) is desirable for improving geometric accuracy,
mechanical properties, and surface finish of nylon, or
polyamide (PA) parts. A modeling and measurement
system was set up to facilitate development of thermal control strategies to improve these characteristics. A SinterStation 2500 SLS machine was used as
a test machine for studying builds of parts made of
DuraformTM PM nylon powder. Internal temperature measurements of the process were made using
resistance temperature detectors (RTDs) embedded
in the part bed powder. Surface temperature was
measured with an infra-red camera aimed through
the front window. A macro-scale time-dependent
thermal numerical model of the build chamber and
powder bins was developed as a means of evaluating
temperature control of the build process. By comparing the measured and predicted temperature profiles,
various estimates of the thermal diffusivity of the nylon powder were evaluated. | null | null | null | null | null | null |
['Wang, Liang', 'Felicelli, Sergio D.', 'Craig, James E.'] | 2020-03-09T13:46:16Z | 2020-03-09T13:46:16Z | 8/23/07 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/80178', 'http://dx.doi.org/10.26153/tsw/7197'] | eng | 2007 International Solid Freeform Fabrication Symposium | Open | Laser Engineered Net Shaping | Thermal Modeling and Experimental Validation in the LENS™ Process | Conference paper | https://repositories.lib.utexas.edu//bitstreams/f8a28d1d-dc92-4cb3-bc91-0ef01b9af3a0/download | null | Several aspects of the thermal behavior of deposited stainless steel 410 (SS410) during the
Laser Engineered Net Shaping (LENSTM) process were investigated experimentally and
numerically. Thermal images in the molten pool and surrounding area were recorded using a
two-wavelength imaging pyrometer system, and analyzed using ThermaVizTM software to obtain
the temperature distribution. The molten pool size, temperature gradient, and cooling rate were
obtained from the recorded history of temperature profiles. The dynamic shape of the molten
pool, including the pool size in both travel direction and depth direction, was investigated and
the effect of different process parameters was illustrated. The thermal experiments were
performed in a LENSTM 850 machine with a 3kW IPG laser for different process parameters. A
three-dimensional finite element model was developed to calculate the temperature distribution
in the LENS process as a function of time and process parameters. The modeling results showed
good agreement with the experimental data. | null | null | null | null | null | null |
['Li, Lan', 'Lough, Cody', 'Replogle, Adriane', 'Bristow, Doug', 'Landers, Robert', 'Kinzel, Edward'] | 2021-11-03T20:46:55Z | 2021-11-03T20:46:55Z | 2017 | Mechanical Engineering | null | https://hdl.handle.net/2152/89929 | eng | 2017 International Solid Freeform Fabrication Symposium | Open | ['thermal modeling', '304L stainless steel', '304L', 'selective laser melting', 'Abaqus'] | Thermal Modeling of 304L Stainless Steel Selective Laser Melting | Conference paper | https://repositories.lib.utexas.edu//bitstreams/eee54541-eef5-482f-aebe-7e6925686df1/download | University of Texas at Austin | This paper describes the continuum thermal modeling of the Selective Laser Melting
(SLM) process for 304L stainless steel using Abaqus. Temperature dependent thermal properties
are obtained from literature and incorporated into the model capturing the change from powder to
fully dense stainless steel. The thermal model predicts the temperature history for multi-track scans
under different process parameters (laser power, effective scanning speed, hatch spacing) which is
used to extract the melt-pool size, solidification rate, and temperature gradients. These are
compared to experimental results obtained from a Renishaw AM250 in terms of the melt pool size,
grain structure, and cell spacing. These experimental results are used to tune unknown simulation
parameters required by the continuum model including the optical penetration depth and thermal
conductivity multiplier for the molten region. This allows the model to yield predictive simulations
of melt pool size and solidification structure of SLM 304L stainless steel. | null | null | null | null | null | null |
['Snider, Elias', 'Gegel, Michelle', 'Holguin, Ryan', 'Dominguez, Cesar', 'Bernardin, John', 'Bristow, Douglas', 'Landers, Robert'] | 2021-12-07T17:23:13Z | 2021-12-07T17:23:13Z | 2021 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90728', 'http://dx.doi.org/10.26153/tsw/17647'] | eng | 2021 International Solid Freeform Fabrication Symposium | Open | ['thermal modeling', 'optical fibers', 'design parameters', 'metal additive manufacturing'] | Thermal Modeling of Fiber Optic Embedment in Metal Additive Manufacturing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/0f44a561-4fbf-478d-9444-597f2bc2df0d/download | University of Texas at Austin | Optical fibers are useful in many sensing applications, including temperature and
radiation sensing as well as distributed strain measurements. These optical fibers may be
consolidated within an additive manufacturing process to help diagnose and/or monitor the
mechanical performance of a part. However, bonding optical fibers to metal parts using laser-based additive manufacturing requires processing temperatures dangerous to the fiber, posing
challenges for fiber survival. To protect the fiber and allow bonding with the metal part, the
fibers are plated with a nickel coating prior to embedment – a process that is costly to perform.
These coatings may also have small internal defects that vary from one fiber to the next. Due to
manufacturing cost and lack of repeatability, it is difficult to experimentally determine
appropriate process parameters, such as laser power and coating thickness. Thus, numerical
modeling offers an efficient approach to exploring embedment parameters and their effect on
fiber survivability. This work employs transient thermal models of embedment processes to
identify and simulate significant design parameters such as coating thickness, embedment
geometry, and cooling time. A transient thermal simulation was developed and is presented
which models fiber optic embedment processes via Laser Engineered Net Shaping (LENS®, a
blown powder, direct energy deposition process) and trends in peak fiber core temperatures, as
well as thermal shock are discussed. | null | null | null | null | null | null |
['Chen, Tiebing', 'Zhang, Yuwen'] | 2020-02-21T21:44:15Z | 2020-02-21T21:44:15Z | 8/3/05 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/80073', 'http://dx.doi.org/10.26153/tsw/7094'] | eng | 2005 International Solid Freeform Fabrication Symposium | Open | Selective Laser Sintering | Thermal Modeling of Metal Powder-Based Selective Laser Sintering | Conference paper | https://repositories.lib.utexas.edu//bitstreams/83bf1855-72d8-4212-aa5a-e4af16755ac7/download | null | In order to get a better understanding of Selective Laser Sintering (SLS) process of the metal
powders, three-dimensional modeling of laser sintering of a metal powder mixture that contains
two kinds of metal powder with significantly different melting points under a moving Gaussian
laser beam is investigated numerically. Laser induced melting and resolidification accompanied
by shrinkage are modeled using a temperature transforming model. The liquid flow of the melted
low melting point metal driven by capillary and gravity forces is also included in the physical
model. Both complete and partial shrinkages are considered in the model. Simulations are
performed for both single line laser scanning and multiple-line laser scanning. The numerical
results are compared with experimental results and a detailed parametric study is performed. The
effects of the moving heat source intensity, the scanning velocity, the thickness of the powder
layer and the number of existing sintered layers underneath on the sintering depth, the shape of
the heat affected zone (HAZ) and the temperature distribution are discussed. The optimized
dimensionless moving heat source intensity increases with increasing scanning velocity in order
to achieve the desired sintering depth and bond the newly sintered layer to the previously
sintered layers. | null | null | null | null | null | null |
['Boillat, Eric', 'Glardon, Rémy', 'Matthey, Marc'] | 2020-02-17T14:58:27Z | 2020-02-17T14:58:27Z | 2004 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/80003', 'http://dx.doi.org/10.26153/tsw/7028'] | eng | 2004 International Solid Freeform Fabrication Symposium | Open | ['Layered Manufacturing Techniques', 'Optimization', 'Cooling'] | Thermal Optimization of Injection Molds Produced by Layered Manufacturing Techniques | Conference paper | https://repositories.lib.utexas.edu//bitstreams/ffe72365-3678-4d81-8280-74172f8775b1/download | null | Producing injection tooling with cooling channels of almost any form seems to be one of the most
promising advantages of Layered Manufacturing Techniques (like Selective Laser Sintering). It could
be efficiently exploited to achieve higher productivity or better quality parts in injection molding.
Unfortunately, at the present time, the lack of data-processing tools to design optimal cooling systems
still prevents us from fully benefiting from this new potential.
The first objective of this paper is to present a methodology for the optimal design of cooling systems
in three-dimensional injection molds. Our optimization process is based on a finite element model of
the mold and on the standard gradient method.
In the second part of this paper, we compare a conventional mold and a mold equipped with a cooling
system optimized by means of the proposed methodology. The comparison is carried out thanks to
an appropriate protocol. The conclusion is that the optimization of the cooling system doubled the
productivity of the mold. | null | null | null | null | null | null |
['Monroe, J.G.', 'Ibrahim, O.T.', 'Thompson, S.M.', 'Shamsaei, N.', 'Bian, L.', 'Elwany, A.'] | 2021-10-21T21:51:17Z | 2021-10-21T21:51:17Z | 2015 | Mechanical Engineering | null | https://hdl.handle.net/2152/89451 | eng | 2015 International Solid Freeform Fabrication Symposium | Open | ['selective laser melting', 'flat-plate oscillating heat pipe', 'FP-OHP', 'titanium alloy', 'Ti-6Al-4V'] | Thermal Performance and Surface Characterization of a Selective Laser Melted Flat-Plate Oscillating Heat Pipe | Conference paper | https://repositories.lib.utexas.edu//bitstreams/fed01271-13dc-4b42-8527-dce3bf57d9e3/download | University of Texas at Austin | A titanium alloy (Ti-6Al-4V) flat-plate oscillating heat pipe (FP-OHP) was fabricated
using Selective Laser Melting (SLM). The 50.8 x 38.1 x 15.75 mm3
FP-OHP consisted of four
integral layers of capillary-sized, circular mini-channels (1.52 mm in diameter). The post-SLM
prototype was de-powdered using pressurized air and a novel layer-by-layer, plug-and-pressurize
design/approach. A vacuum-grade port was threaded into the FP-OHP, and the heat pipe was
charged with acetone (~70% by volume) then hermetically sealed. Experiments were conducted
to characterize the thermal performance and functionality of the multi-layered FP-OHP. Results
indicate that the acetone-filled FP-OHP operates and can provide for an 800% increase in
effective thermal conductivity relative to pure Ti-6Al-4V. The build integrity of the FP-OHP was
investigated by shearing along its width to inspect the channel-area surface using field emission
scanning electron microscopy (SEM) and laser triangulation for channel topography. The mean
surface roughness was found to be approximately 45 micrometers and characterized by partiallymelted, abraded particles. This study demonstrates the appeal of additive manufacturing for
fabrication of customized heat transfer media traditionally challenging to realize. | null | null | null | null | null | null |
['Bontha, Srikanth', 'Klingbeil, Nathan W.'] | 2019-11-20T16:24:50Z | 2019-11-20T16:24:50Z | 2003 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/78472', 'http://dx.doi.org/10.26153/tsw/5557'] | eng | 2003 International Solid Freeform Fabrication Symposium | Open | Thermal Process | Thermal Process Maps for Controlling Microstructure in Laser-Based Solid Freeform Fabrication | Conference paper | https://repositories.lib.utexas.edu//bitstreams/0220de9f-dde6-4852-b868-2bc957a8a43a/download | null | The ability to predict and control microstructure in laser deposited materials requires an
understanding of the thermal conditions at the onset of solidification. The focus of this work is
the development of thermal process maps relating solidification cooling rate and thermal gradient
(the key parameters controlling microstructure) to laser deposition process variables (laser power
and velocity). The approach employs the well-known Rosenthal solution for a moving point heat
source traversing an infinite substrate. Cooling rates and thermal gradients at the onset of
solidification are numerically extracted from the Rosenthal solution throughout the depth of the
melt pool, and dimensionless process maps are presented for both thin-wall (2-D) and bulky (3-
D) geometries. In addition, results for both small-scale (LENSTM) and large-scale (higher power)
processes are plotted on solidification maps for predicting grain morphology in Ti-6Al-4V.
Although the Rosenthal results neglect temperature-dependent properties and latent heat effects,
a comparison with 2-D FEM results over a range of LENSTM process variables suggests that they
can provide reasonable estimates of trends in solidification microstructure. The results of this
work suggest that changes in process variables could potentially result in a grading of the
microstructure (both grain size and morphology) throughout the depth of the deposit, and that the
size-scale of the laser deposition process is important. | null | null | null | null | null | null |
['Carter, William', 'Masuo, Christopher', 'Nycz, Andrzej', 'Noakes, Mark', 'Vaughan, Derek'] | 2021-11-30T19:24:28Z | 2021-11-30T19:24:28Z | 2019 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90520', 'http://dx.doi.org/10.26153/tsw/17439'] | eng | 2019 International Solid Freeform Fabrication Symposium | Open | ['wire-arc additive manufacturing', 'thermal imaging', 'process monitoring', 'IR camera', 'MIG'] | Thermal Process Monitoring for Wire-Arc Additive Manufacturing using IR Cameras | Conference paper | https://repositories.lib.utexas.edu//bitstreams/51f7751a-ffe1-4a46-89d2-d5ab365acbda/download | University of Texas at Austin | Wire-arc additive manufacturing systems use robotic MIG welders to build parts using
welding wire. As a part is built the temperature rises as energy is input and the thermal mass
increases. While some pre-heat is ideal for welding, improper thermal management can lead to
defects and negatively affect material properties. Thermal imaging allows for non-contact
thermal monitoring and can be used to track thermal gradients as well as layer temperatures
before and after deposition providing a method to ensure proper thermal management. A typical
IR camera setup on an mBAAM system is discussed along with methods to use thermal
monitoring to improve material properties and reduce defects in the final part. | null | null | null | null | null | null |
['Xue, Samuel', 'Barlow, J.W.'] | 2018-04-12T17:26:40Z | 2018-04-12T17:26:40Z | 1990 | Mechanical Engineering | doi:10.15781/T2736MK0M | http://hdl.handle.net/2152/64271 | eng | 1990 International Solid Freeform Fabrication Symposium | Open | ['Chemical Engineering Department', 'thermal conductivities', 'differential scanning calorimetry'] | Thermal Properties of Powders | Conference paper | https://repositories.lib.utexas.edu//bitstreams/4eed7f4f-e749-46d5-a1dc-21145f2c1488/download | null | This paper presents measurements of the specific heats of various powders, including nylon,
ABS, PVC, and two kinds of wax. An unsteady-state conduction technique is also presented for
measuring the thermal conductivities of these powders at temperatures below those where sintering
occurs. Both specific heats and thermal conductivities are found to be functions of temperature. | null | null | null | null | null | null |
['Whiting, J.', 'Lane, B.', 'Chou, K.', 'Cheng, B.'] | 2021-11-02T13:32:55Z | 2021-11-02T13:32:55Z | 2017 | Mechanical Engineering | null | https://hdl.handle.net/2152/89797 | eng | 2017 International Solid Freeform Fabrication Symposium | Open | ['laser powder bed fusion', 'thermal properties', 'thermal diffusivity', 'thermal conductivity'] | Thermal Property Measurement Methods and Analysis for Additive Manufacturing Solids and Powders | Conference paper | https://repositories.lib.utexas.edu//bitstreams/40c241c7-5d33-4634-a42e-86385fa0b194/download | University of Texas at Austin | Thermal properties of additive manufacturing (AM) solids and precursor materials are important
factors for build process and part performance. However, measured thermal properties are not
well documented, despite being used extensively in AM modeling and simulation. The National
Institute of Standards and Technology (NIST) and the University of Louisville are developing the
measurement science for AM material thermal properties. New measurement methods, sample
preparation techniques, and results are demonstrated for laser flash (LF) thermal diffusivity
measurements on metal AM solids and powders. Due to the complexity of these materials, new
sample fabrication methods are developed and demonstrated. Results from LF measurements are
presented and compared. | null | null | null | null | null | null |
['Ji, Yi', 'Taylor, Samantha', 'Fish, Scott', 'Beaman, Joseph'] | 2021-11-03T21:20:24Z | 2021-11-03T21:20:24Z | 2017 | Mechanical Engineering | null | https://hdl.handle.net/2152/89935 | eng | 2017 International Solid Freeform Fabrication Symposium | Open | ['cooldown phase', 'cool down control', 'thermal simulation', 'validation', 'selective laser sintering'] | Thermal Simulation and Experiment Validation of Cooldown Phase of Selective Laser Sintering (SLS) | Conference paper | https://repositories.lib.utexas.edu//bitstreams/45c192fc-48b9-4cc0-9e70-cbb1694beeb7/download | University of Texas at Austin | Thermal stresses, induced by inhomogeneous temperature distribution inside a part during
the cooldown phase of selective laser sintering, can be a major cause of part rejection for geometric
deviation from its as-built specification. A validated cooldown simulation can provide predictions
of temperature distribution in both parts and part cake which may enable alternative cooling
profiles to reduce the likelihood of such rejections. This work describes experiments and
comparative simulations developed to validate a sample tool for developing cool down control
profiles in an SLS machine. In the experiments, thermocouples were inserted inside the part cake
to monitor temperature at preselected locations during cooldown. The results from initial
experiments and simulations were compared at these locations, to obtain improved estimates of
uncertain powder conductivity and convective heat transfer parameters. The resulting simulation
was then compared with independent experiments to evaluate the accuracy of such simulations.
Though diffusion time in the part cake prevents active closed loop control in cooldown based on
thermal measurements at the part, the simulation can be used to determine an open loop control
profile for the build box heaters based on temperature gradient and resultant stresses inside the
part. | null | null | null | null | null | null |
['Huseynov, Orkhan', 'Al-Shaikh Ali, Mohammad', 'Fidan, Ismail'] | 2024-03-26T20:20:56Z | 2024-03-26T20:20:56Z | 2023 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/124393', 'https://doi.org/10.26153/tsw/51001'] | en_US | 2023 International Solid Freeform Fabrication Symposium | Open | ['additive manufacturing', 'material extrusion', 'thermal simulation', 'print bed', 'thermal history'] | THERMAL SIMULATION OF THE MATERIAL EXTRUSION PROCESS WITH DIFFERENT PRINT BED BOUNDARY CONDITIONS | Conference paper | https://repositories.lib.utexas.edu//bitstreams/16ddba92-fca1-4859-9b67-fc58b07f096c/download | University of Texas at Austin | The temperature evolution in the material extrusion (MEX) process significantly affects the
stability and bonding of 3D printed parts. Numerous studies have focused on developing models
to capture the temperature history of the MEX process. However, there remains a need to explore
the influence of different boundary conditions applied to the print bed. Additionally, the size of the
bed relative to the 3D printed object has not been extensively investigated. This study aims to
analyze the thermal behavior of the first layer in MEX by considering various boundary conditions
and bed sizes. The obtained results will contribute to the development of faster yet reliable models
for simulating the temperature variation in the MEX process. | null | null | null | null | null | null |
['Liu, Tao', 'Kinzel, Edward C.', 'Leu, Ming C.'] | 2024-03-27T16:00:08Z | 2024-03-27T16:00:08Z | 2023 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/124497', 'https://doi.org/10.26153/tsw/51105'] | en | 2023 International Solid Freeform Fabrication Symposium | Open | ['laser powder bed fusion', 'thermal stress', 'additive manufacturing'] | Thermal Stress Prediction in Laser Powder Bed Fusion | Conference paper | https://repositories.lib.utexas.edu//bitstreams/455580a6-bdbd-41ef-be31-dcc2e444567b/download | null | This research applies Green's function solutions to simulate temperature and thermal stress fields
in laser powder-bed fusion (LPBF) processes. Using a semi-infinite domain and 2D Gaussian laser
profiles, the analytical model achieves high computational efficiency, has the potential for realtime controls and predictions in LPBF processes. The model highlights the role of principal
stresses in determining crack formations, aligning closely with experimental results. | null | null | null | null | null | null |
['Cheng, Bo', 'Chou, Kevin'] | 2021-10-18T21:25:59Z | 2021-10-18T21:25:59Z | 2014 | Mechanical Engineering | null | https://hdl.handle.net/2152/89251 | eng | 2014 International Solid Freeform Fabrication Symposium | Open | ['electron beam additive manufacturing', 'overhang', 'thermomechanical simulation'] | Thermal Stresses Associated with Part Overhang Geometry in Electron Beam Additive Manufacturing: Process Parameter Effects | Conference paper | https://repositories.lib.utexas.edu//bitstreams/e0650f15-05bd-4d17-b94a-9e2e0cdd6ed0/download | University of Texas at Austin | For powder-bed electron beam additive manufacturing (EBAM), support structures are
required when fabricating an overhang to prevent defects such as curling, which is due to the
complex thermomechanical process in EBAM. In this study, finite element modeling is
developed to simulate the thermomechanical process in EBAM in building overhang part.
Thermomechanical characteristics such as thermal gradients and thermal stresses around the
overhang build are evaluated and analyzed. The model is applied to evaluate process parameter
effects on the severity of thermal stresses. The major results are summarized as follows. For a
uniform set of process parameters, the overhang areas have a higher maximum temperature, a
higher tensile stress, and a larger distortion than the areas above a solid substrate. A higher
energy density input, e.g., a lower beam speed or a higher beam current may cause more severe
curling at the overhang area. | null | null | null | null | null | null |
['Pohl, Haiko', 'Simchi, Abdolreza', 'Issa, Munther', 'Dias, Hugo Calefi'] | 2019-10-18T15:32:51Z | 2019-10-18T15:32:51Z | 2001 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/76240', 'http://dx.doi.org/10.26153/tsw/3329'] | eng | 2001 International Solid Freeform Fabrication Symposium | Open | Sintering | Thermal Stresses in Direct Metal Laser Sintering | Conference paper | https://repositories.lib.utexas.edu//bitstreams/390411c4-073b-4391-bb76-a43cf7d760e9/download | null | In Direct Metal Laser Sintering objects are created by sequential sintering loose metal
powder particles by means of laser technology. When the laser sintering process involves
temperature gradients, thermal stresses develop. Corresponding residual stresses induce warping
of the densified structure leading to unacceptable tolerance losses. This paper examines the role
of laser beam scan patterns on the resulting stresses and warpage of direct metal laser sintered
plate-shaped specimens. The effects of a large variety of laser sintering parameters are described.
It can be shown that the optimization of process conditions and material aspects results in a
significant reduction of thermal stresses. | null | null | null | null | null | null |
['Mertens, A.', 'Dedry, O.', 'Reuter, D.', 'Rigo, O.', 'Lecomte-Beckers, J.'] | 2021-10-21T15:27:54Z | 2021-10-21T15:27:54Z | 2015 | Mechanical Engineering | null | https://hdl.handle.net/2152/89396 | eng | 2015 International Solid Freeform Fabrication Symposium | Open | ['Laser Beam Melting', 'AlSi10Mg', 'thermal treatments'] | Thermal Treatments of AlSi10Mg Processed by Laser Beam Melting | Conference paper | https://repositories.lib.utexas.edu//bitstreams/1576c5fb-259a-4b2d-9a1a-a9663f89f6b6/download | University of Texas at Austin | Recent studies have shown that AlSi10Mg processed by Laser Beam Melting (LBM)
exhibits a much finer microstructure when compared to its cast counterpart as a consequence of
the much faster cooling rates imposed in the LBM process. Such microstructural refinement
causes a significant increase in strength and hardness, to such an extent that as-fabricated LBM
AlSi10Mg was reported to present hardness value of 127 ± 3 Hv0.5, similar to the hardness of
high pressure die cast AlSi10Mg in the aged condition (i.e. 130-133 Hv). Yet, little attention has
been given so far to the influence of thermal treatments on the microstructure and mechanical
behavior of LBM AlSi10Mg. The present work hence aims to investigate the effect of two
different types of heat treatments – i.e. (i) stress relief and (ii) solutionizing and ageing − on the
microstructure, hardness and tensile properties of LBM AlSi10Mg. | null | null | null | null | null | null |
['Duty, Chad', 'Johnson, Ryan', 'Jean, Daniel', 'Bondi, Scott', 'Lackey, W. Jack'] | 2019-10-18T15:36:30Z | 2019-10-18T15:36:30Z | 2001 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/76241', 'http://dx.doi.org/10.26153/tsw/3330'] | eng | 2001 International Solid Freeform Fabrication Symposium | Open | Deposition | Thermal, Fluid, and Mass Transport Modeling of a Gas-Jet Reagent Delivery System for Laser Chemical Vapor Deposition (LCVD) | Conference paper | https://repositories.lib.utexas.edu//bitstreams/76de83c2-67d6-4ba3-a7b9-0e70253973cc/download | null | A gas-jet reagent delivery system for laser chemical vapor deposition (LCVD) is modeled
with respect to heat transfer, fluid flow, and mass transport. A commercial package was used to
model the geometry and flow field surrounding an LCVD reaction zone. The deposition
temperature was analyzed for various materials and flow conditions. The forced flow
environment was compared against buoyancy-driven flow, which is more typical of a statically
filled chamber. A finite difference code was also developed to analyze the effect of the gas-jet
on the concentration gradients above the deposition zone. | This work was supported by the National Science Foundation, the Engineering Research
Program of the Office of Basic Energy Sciences at the U. S. Department of Energy and the
Georgia Institute of Technology with significant input from Dr. Andrei Fedorov. | null | null | null | null | null |
['Ulett, J.S.', 'Benson-Tolle, T.', 'Schultz, J.W.', 'Chartoff, R. P.'] | 2019-02-26T17:57:42Z | 2019-02-26T17:57:42Z | 1998 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/73491', 'http://dx.doi.org/10.26153/tsw/641'] | eng | 1998 International Solid Freeform Fabrication Symposium | Open | ['Liquid crystal', 'stereolithography'] | Thermal-Expansion and Fracture Toughness Properties ofParts made from Liquid Crystal Stereolithography Resins | Conference paper | https://repositories.lib.utexas.edu//bitstreams/f93474a6-5523-4049-be63-a5c9525935c4/download | null | Liquid crystal (LC) resins are a new kind ofstereolithography material that can produce
parts with structured or ordered morphologies instead ofthe amorphous morphologies that result
from standard resins. The LC molecules can be aligned before cure resulting in an anisotropic
crosslinked network when the laser induced polymerization "locks-in" the alignment. Previous
papers have explored liquid crystal orientation dynamics [1], the effects of orientation on viscoelastic and mechanical properties [2,3], and the processing ofLC resins by stereolithography [4].
This paper considers the effects ofmorphology on fracture toughness and thermal-expansion
properties. Both toughness and thermal-stability continue to be important issues for
stereolithography parts. The use ofLC resins may provide a way to significantly improve
performance in both ofthese areas, and in addition result in parts with high upper use .
temperatures. | null | null | null | null | null | null |
['Weflen, E.D.', 'Peters, F.E.', 'Frank, M.C.'] | 2023-04-03T17:30:09Z | 2023-04-03T17:30:09Z | 2022 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/117723', 'http://dx.doi.org/10.26153/tsw/44602'] | eng | 2022 International Solid Freeform Fabrication Symposium | Open | Additive manufacturing | Thermally Switchable Build Table by Mechanical Interlocking for Additive Manufacturing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/8e20718d-c2c2-4104-84cd-dfbd82c03652/download | null | This work presents a method for achieving a thermally switchable bond on a build table
for Additive Manufacturing using mechanically interlocking features. Removal of parts from the
build table remains a challenge. Furthermore, the residual stress that develops as multiple layers
are deposited in an ambient environment can lead to the part detaching from the build table if
bonding is insufficient. To achieve ample part to build table bonding, undercut features are
machined into a metal build table onto which the molten polymer is extruded. Upon solidification,
a mechanical bond is formed. The part can then be easily removed through rapid heating of the
undercut features, resulting in a loss of mechanical bonding. We present results from our lab-scale
setup allowing fundamental studies of the core physics. The method can easily be scaled larger or
smaller by proportionally sizing the undercut features to the plastic extrusion bead size and
parameters. | null | null | null | null | null | null |
['Bharvirkar, Manish', 'Nguyen, Phong', 'Pistor, Christoph'] | 2019-03-14T17:15:30Z | 2019-03-14T17:15:30Z | 1999 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/73682', 'http://dx.doi.org/10.26153/tsw/824'] | eng | 1999 International Solid Freeform Fabrication Symposium | Open | ['FDM', 'ABS'] | Thermo-mechanical Analysis of Parts Fabricated via Fused Deposition Modeling (FDM) | Conference paper | https://repositories.lib.utexas.edu//bitstreams/300b82e7-7862-479c-81fa-b629bd6797bf/download | null | The quality of Fused Deposition Modeling parts that are built using the standard parallel
road approach depends significantly on the orientation of the slices. In this study the expansion
coefficient, tensile strength and elastic. modulus of FDM parts made from ABS were determined
experimentally. The parts were built using the standard toolpath (parallel roads) with a uni
directional stacking sequence. The results were used to determine the thermo-mechanical
properties for an.individual slice. Classical lamination theory was applied to predict properties
and stiffness of matrix parts with arbitrarily oriented stacking sequences. The results of these
predictions are compared with experimental results for a quasi-isotropic stacking sequence. | null | null | null | null | null | null |
['Zekovic, Srdja', 'Dwivedi, Rajeev', 'Kovacevic, Radovan'] | 2020-02-21T21:40:41Z | 2020-02-21T21:40:41Z | 8/26/05 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/80072', 'http://dx.doi.org/10.26153/tsw/7093'] | eng | 2005 International Solid Freeform Fabrication Symposium | Open | finite element analysis | Thermo-structural Finite Element Analysis of Direct Laser Metal Deposited Thin-Walled Structures | Conference paper | https://repositories.lib.utexas.edu//bitstreams/bd487346-0b12-47cb-aabe-c69325356feb/download | null | Multilayer direct laser metal deposition is a fabrication process in which the parts are fabricated
by creating a molten pool into which particles are injected. During fabrication, a complex
thermal history is experienced in different regions of the build, depending on the process
parameters and part geometry. The thermal history induces residual stress accumulation in the
buildup, which is the main cause of cracking during the fabrication. The management of residual
stress and the resulting distortion is a critical factor for the success of the process. A thermostructural finite element model (FEM) of the process is developed, and the analysis reveals
different patterns of residual stress in the thin-walled structures depending on the deposition
strategy and the geometry of the structures. The residual stress patterns obtained from finite
element analysis (FEA) are in good agreement with the experimental results. | null | null | null | null | null | null |
['Gunaratnam, Rana', 'Sparks, Todd E.', 'Liou, Frank'] | 2020-03-09T13:27:20Z | 2020-03-09T13:27:20Z | 8/28/07 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/80173', 'http://dx.doi.org/10.26153/tsw/7192'] | eng | 2007 International Solid Freeform Fabrication Symposium | Open | Laser Aided Manufacturing Process | Thermocouple Embedding for the Production of a Substrate for Rapid Manufacturing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/ab469a19-7637-4d61-aae4-71897cb8eb4a/download | null | null | null | null | null | null | null | null |
['Karnati, Sreekar', 'Sparks, Todd', 'Liou, Frank'] | 2021-10-19T15:15:04Z | 2021-10-19T15:15:04Z | 2014 | Mechanical Engineering | null | https://hdl.handle.net/2152/89294 | eng | 2014 International Solid Freeform Fabrication Symposium | Open | ['laser metal deposition', 'thermal qualities', 'thin wall geometry', 'thermography'] | Thermographic Investigation of Laser Metal Deposition | Conference paper | https://repositories.lib.utexas.edu//bitstreams/cbd088cc-4efe-4a07-b70e-a84e1b60398e/download | University of Texas at Austin | Primitive stages of studies on and with additive manufacturing techniques popularly involve thin
wall geometry. In the current effort attempts were made to capture various thermal aspects
during deposition of a thin wall geometry. The thermo-graphic data was captured using a FLIR
A615 infrared camera. Post processing using edge detection algorithms and image processing
techniques, the geometric and thermal aspects of meltpool and tail of the meltpool were obtained.
The effect of geometry and power on shape of the meltpool and its tail were obtained. The
depositions of SS 316 with varying power. These observations were discussed and analyzed in
aim to perform planned deposition of functionally gradient materials in future. | null | null | null | null | null | null |
['Lane, Brandon', 'Moylan, Shawn', 'Whitenton, Eric', 'Ma, Li'] | 2021-10-20T20:55:37Z | 2021-10-20T20:55:37Z | 2015 | Mechanical Engineering | null | https://hdl.handle.net/2152/89360 | eng | 2015 International Solid Freeform Fabrication Symposium | Open | ['laser powder bed fusion', 'commercial manufacturing', 'thermographic measurements', 'melt pool region', 'National Institute Standards and Technology'] | Thermographic Measurements of the Commercial Laser Powder Bed Fusion Process at NIST | Conference paper | https://repositories.lib.utexas.edu//bitstreams/593588e0-bd9a-4ec9-af3e-e4102312c6ce/download | University of Texas at Austin | Measurement of the high-temperature melt pool region in the laser powder bed fusion (LPBF) process is a primary focus of researchers to further understand the dynamic physics of the
heating, melting, adhesion, and cooling which define this commercially popular additive
manufacturing process. This paper will detail the design, execution, and results of high speed,
high magnification in-situ thermographic measurements conducted at the National Institute of
Standards and Technology (NIST) focusing on the melt pool region of a commercial L-PBF
process. Multiple phenomena are observed including plasma plume and hot particle ejection
from the melt region. The thermographic measurement process will be detailed with emphasis
on the ‘measurability’ of observed phenomena and the sources of measurement uncertainty.
Further discussion will relate these thermographic results to other efforts at NIST towards L-PBF
process finite element simulation and development of in-situ sensing and control methodologies. | null | null | null | null | null | null |
['Krauss, H.', 'Eschey, C.', 'Zaeh, M.F.'] | 2021-10-07T14:53:16Z | 2021-10-07T14:53:16Z | 8/22/12 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88469', 'http://dx.doi.org/10.26153/tsw/15406'] | eng | 2012 International Solid Freeform Fabrication Symposium | Open | ['Selective Laser Melting', 'thermography', 'process errors', 'heat dissipation', 'temperature distribution'] | Thermography for Monitoring the Selective Laser Melting Process | Conference paper | https://repositories.lib.utexas.edu//bitstreams/4187b676-157b-43f6-a17b-50f9a8d480dc/download | University of Texas at Austin | A lot of strategies exist to monitor and control additive layer manufacturing processes.
Basically one can distinguish between coaxially monitoring the process zone and monitoring the
complete layer currently being built. Since Selective Laser Melting is a thermal process, a lot of
information about the process and in consequence about the resulting part quality can be gathered
by monitoring the temperature distribution of a complete layer and its temporal evolution. It
depends on the geometrical configuration of parts being built and the quality of the powder layer
deposition. In this paper, process errors originating from insufficient heat dissipation are
investigated as well as the limits for detecting pores and other irregularities by observation of the
temperature distribution. | null | null | null | null | null | null |
['Chin, R.K.', 'Beuth, J.L.', 'Amon, C.H.'] | 2018-11-16T14:55:26Z | 2018-11-16T14:55:26Z | 1996 | Mechanical Engineering | doi:10.15781/T2QB9VR6J | http://hdl.handle.net/2152/70283 | eng | 1996 International Solid Freeform Fabrication Symposium | Open | ['SDM', 'manufacturing methods', 'stress distributions'] | Thermomechanical Modeling of Successive Material Deposition in Layered Manufacturing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/caf43ddb-31d5-4db4-a935-4c6f0a33026c/download | null | Residual stress build-up due to successive deposition of superheated molten metal onto
metal substrates is modeled for application to layered manufacturing methods. This work is
specifically applied to microcasting, which is a deposition process used within shape deposition
manufacturing. One-dimensional thennal and mechanical models are used to predict temperature
and stress evolution related to two physical phenomena. First, the effect of thennal cycling by
newly deposited material on stress states in previously deposited and cooled layers is investigated.
Here, deposited molten metal solidifies and cools to room temperature before new molten metal is
deposited. For this case, predicted stress distributions as a function of depth are relatively
uncomplicated and can be related to residual stress-induced part tolerance loss. In the second case,
the effect of localized preheating by previously deposited material is investigated. In this model,
molten metal is successively deposited at a rate comparable to that used to deposit individual
droplets in the microcasting process. Results indicate that although preheating by previously
deposited material strongly affects transient stresses, final stress states are not substantially altered. | null | null | null | null | null | null |
['Jaksch, A.', 'Spinola, M.', 'Cholewa, C.', 'Pflug, L.', 'Stingl, M.', 'Drummer, D.'] | 2023-04-05T17:14:02Z | 2023-04-05T17:14:02Z | 2022 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/117780', 'http://dx.doi.org/10.26153/tsw/44659'] | eng | 2022 International Solid Freeform Fabrication Symposium | Open | PBF-LB/P | Thin-Walled Part Properties in PBF-LB/P — Experimental Understanding and Nonlocal Material Model | Conference paper | https://repositories.lib.utexas.edu//bitstreams/77c6dd55-0296-472a-bf75-3a9a869f7876/download | null | to fully realizing the potential of lightweight design in powder bed fusion of polymers (PBF-LB/P). In
this work, parts built with rectangular cross sections of different sizes and orientations are described by their
geometry, surface roughness, mechanical characteristics, and specific component geometry dependent on energy
input. Experimental findings are supported by a nonlocal material model developed to adequately describe
weakened material behavior at the surface of PBF-LB/P parts. This approach allows the simulation of the elastic
modulus and density for complex part geometries while simultaneously considering boundary effects.
Furthermore, the volume-surface ratio for thin-walled components were linearly correlated to the rectangular
cross sections in different building orientations. This uniformity indicates that this ratio is a suitable quantity to
consider. Therefore, the process knowledge is improved, especially in new design standards for thin-walled
structures in PBF-LB/P. | null | null | null | null | null | null |
['Boillat, E.', 'Kolossov, S.', 'Glardon, R.'] | 2019-10-24T17:46:54Z | 2019-10-24T17:46:54Z | 2002 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/77406', 'http://dx.doi.org/10.26153/tsw/4495'] | eng | 2002 International Solid Freeform Fabrication Symposium | Open | Laser Sintering | A Three Dimensional FEM-Simulation of the Selective Laser Sintering Process with Locally Refined Meshes and Non-Constant Thermal Conductivity | Conference paper | https://repositories.lib.utexas.edu//bitstreams/5d8a9fa0-7863-4dbf-b56a-4b0908e1a52d/download | null | null | null | null | null | null | null | null |
Sun, Ming-shen M. | 2018-04-16T17:27:11Z | 2018-04-16T17:27:11Z | 1991 | Mechanical Engineering | doi:10.15781/T28S4K60Q | http://hdl.handle.net/2152/64311 | eng | 1991 International Solid Freeform Fabrication Symposium | Open | ['SLS', 'Selective Laser Sintering', 'model', 'sintering'] | A Three Dimensional Model for Selective Laser Sintering | Conference paper | https://repositories.lib.utexas.edu//bitstreams/b4030075-4cf9-47b9-95b9-30d462a6a5a1/download | null | null | null | null | null | null | null | null |
['Kernan, Brian D.', 'Sachs, Emanuel M.', 'Oliveria, Mark A.', 'Cima, Michael J.'] | 2019-11-21T18:44:30Z | 2019-11-21T18:44:30Z | 2003 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/78566', 'http://dx.doi.org/10.26153/tsw/5622'] | eng | 2003 International Solid Freeform Fabrication Symposium | Open | Carbide-Cobalt | Three Dimensional Printing of Tungsten Carbide-Cobalt Using a Cobalt Oxide Precursor | Conference paper | https://repositories.lib.utexas.edu//bitstreams/5c3b7a15-5ce9-4894-85d5-54e68f187fcd/download | null | Tungsten Carbide 10 wt% Cobalt parts were formed by Slurry-based Three
Dimensional Printing (3DPTM). The slurry contained a mixture of Tungsten Carbide and
Cobalt Oxide powders, as well as dispersing and redispersing agents. The cobalt oxide is
fully reduced to cobalt metal during the early stages of the sintering process. A new binder
system, polyethylenimine, is described for use with powders with acidic surfaces, such as
WC. Sintered densities approach the theoretical values for WC-10% Co, and the
microstructures produced are similar to those of conventionally processed (press and sinter)
materials. Up to four parts were produced in a single print run using a layer thickness of 25
Pm, with good dimensional agreement between them, and within the range of target
dimensions after sintering. | null | null | null | null | null | null |
['Cima, Michael J.', 'Sachs, Emanuel M.'] | 2018-04-17T17:59:40Z | 2018-04-17T17:59:40Z | 1991 | Mechanical Engineering | doi:10.15781/T2DB7W70S | http://hdl.handle.net/2152/64335 | eng | 1991 International Solid Freeform Fabrication Symposium | Open | ['Department of Materials Science and Mechanical Engineering', 'Three Dimensional Printing', 'CAD', 'SLS'] | Three Dimensional Printing: Form, Materials, and Performance | Conference paper | https://repositories.lib.utexas.edu//bitstreams/4a91dec9-3ba5-4a65-ba19-0e55500d2bb6/download | null | null | null | null | null | null | null | null |
['Sachs, Emanuel', 'Cima, Michael', 'Cornie, James'] | 2018-04-10T16:47:13Z | 2018-04-10T16:47:13Z | 1990 | Mechanical Engineering | doi:10.15781/T2GT5FZ4F | http://hdl.handle.net/2152/64236 | eng | 1990 International Solid Freeform Fabrication Symposium | Open | ['Three Dimensional Printing', 'Industrial productivity', 'sequential formation', 'ink-jet printing'] | Three Dimensional Printing: Rapid Tooling and Prototypes Directly from CAD Representation | Conference paper | https://repositories.lib.utexas.edu//bitstreams/c0ba7c81-35a2-497d-a309-e93acea1a79f/download | null | Industrial productivity and competitive success depend on fast, efficient product
development technologies. The flexible manufacture of tooling and mechanical prototypes
can greatly reduce the time required for bringing a product to market. Tooling frequently
dominates manufacturing time and cost, thereby determining the minimum economic batch
size for a given process. Tooling can be extremely complex and is generally one-of-a-kind,
requiring much human attention to detail. As a result, fabrication of tooling for such
processes as injection molding or lost wax casting, commonly requires several months of
work. Three Dimensional Printing offers an alternative to conventional options which do
not adequately answer the demands for rapid prototyping and speedy, low-cost production
of tooling. | null | null | null | null | null | null |
['Awenlimobor, Aigbe', 'Smith, Douglas E.', 'Wang, Zhaogui', 'Luo, Chenjun'] | 2023-01-26T15:28:45Z | 2023-01-26T15:28:45Z | 2022 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/117317', 'http://dx.doi.org/10.26153/tsw/44198'] | eng | 2022 International Solid Freeform Fabrication Symposium | Open | 3D | Three-dimensional (3D) Simulation of Micro-Void Development within Large Scale Polymer Composite Deposition Beads | Conference paper | https://repositories.lib.utexas.edu//bitstreams/8e7c85a4-8280-4640-88d8-9c482d6d6ee6/download | null | Manufacturing (BAAM) are largely affected by inherent bead microstructural features
such as voids. Unfortunately, our understanding of void nucleation and evolution during polymer
deposition process is lacking. Flow modeling focused on the associated microstructural formation
provides a means for better understanding the process-structure-properties relations in large area
extrusion deposition additive manufacturing of fiber reinforced composites. Our prior computational
effort that investigated mechanisms that may promote micro-void formation was based on 2-dimensional
planar models of a single ellipsoidal fiber motion in purely viscous polymer extrusion/deposition flow
through a BAAM nozzle. Here we present a 3D finite element modelling approach to simulate single fiber
out-of-plane rotations utilizing velocity and velocity gradient values computed along streamlines
obtained from a 3D extrusion/deposition simulation of the BAAM polymer deposition process. The
pressure distribution on the fiber’s surface along the flow path provides new insight into potential
micro-void nucleation mechanism. Results show low pressure regions occur near the fiber’s surface
which varies across the printed bead and through its thickness. | null | null | null | null | null | null |
['Chen, Y.', 'Bartzos, D.', 'Liang, S.', 'Lu, Y.', 'Jafari, M.', 'Langrana, N.A.', 'Pilleux, M.E.', 'Allahverdi, M.', 'Danforth, S.C.', 'Safari, A.'] | 2019-09-18T16:34:12Z | 2019-09-18T16:34:12Z | 2000 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/75899', 'http://dx.doi.org/10.26153/tsw/2999'] | eng | 2000 International Solid Freeform Fabrication Symposium | Open | Alumina | Three-dimensional Alumina Photonic Bandgap Structures: Numerical Simulation and Fabrication by Fused Deposition of Multimaterials | Conference paper | https://repositories.lib.utexas.edu//bitstreams/0c445a1f-4d91-43b7-a140-53901622e6a2/download | null | Three-dimensional photonic bandgap (PBG) structures using alumina (Al2O3) as the
high permittivity material were modeled and fabricated. A finite element method and a realtime electromagnetic wave propagation software were used to simulate and design the layered
PBG structures for their use in the microwave frequency range. The modeling obtained a 3-D
photonic bandgap in the 16-23 GHz range. Fused deposition of multimaterials (FDMM)
technology was then used to manufacture PBG structures. FDMM provides a computercontrolled process to generate 3-D structures, allowing high fabrication flexibility and
efficiency. These PBG structures are potential candidates for applications in advanced
communication systems. | New Jersey Commission of Science and Technology under the Research Excellence Program. | null | null | null | null | ['https://sffsymposium.engr.utexas.edu/Manuscripts/2000/2000-04-Bandyopadhyay.pdf', 'https://sffsymposium.engr.utexas.edu/Manuscripts/2000/2000-05-Chen.pdf'] |
['Mizukami, Yoshiaki', 'Osakada, Kozo'] | 2019-10-24T18:27:08Z | 2019-10-24T18:27:08Z | 2002 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/77420', 'http://dx.doi.org/10.26153/tsw/4509'] | eng | 2002 International Solid Freeform Fabrication Symposium | Open | Metallic Parts | Three-Dimensional Fabrication of Metallic Parts and Molds Using Hybrid Process of Powder Layer Compaction and Milling | Conference paper | https://repositories.lib.utexas.edu//bitstreams/14876e36-2635-4863-b1ef-b34c6f234667/download | null | In order to produce three-dimensional models with cemented carbide powders, a freeform
fabrication method named Layered Compaction Manufacturing (LCM), which is a hybrid process
of powder compaction and CNC milling in layer-by-layer additive manner, is proposed. The
feasibility of the LCM process is confirmed by making a WC-9wt%Co carbide model. The
connecting strength between the layers of the model after sintering is evaluated by the bending
test. It is found that the transverse strength of the sintered products is higher than 2 GPa.
A WC-9wt%Co model with inside channels for temperature control is successfully fabricated
using a paraffin wax as a sacrificial material in the LCM process. | null | null | null | null | null | null |
['Han, Quanquan', 'Setchi, Rossitza', 'Evans, Sam L.', 'Qiu, Chunlei'] | 2021-10-26T18:10:31Z | 2021-10-26T18:10:31Z | 2016 | Mechanical Engineering | null | https://hdl.handle.net/2152/89546 | eng | 2016 International Solid Freeform Fabrication Symposium | Open | ['selective laser melting', 'thermal performance', 'three-dimensional finite element', 'Al-Al2O3 powder', 'aluminum-based composites'] | Three-Dimensional Finite Element Thermal Analysis in Selective Laser Melting of Al-Al2O3 Powder | Conference paper | https://repositories.lib.utexas.edu//bitstreams/47eef9e5-e092-4423-be21-c7fe1c0dbd62/download | University of Texas at Austin | The selective laser melting (SLM) of aluminium-based composites continues to be a
challenge due to the high reflectivity, high thermal conductivity and oxidation of aluminium, all
of which directly influence the thermal performance of each layer during SLM. Due to the
extremely rapid melting and cooling rate of aluminium, however, it is difficult to measure thermal
performance within practical SLM applications. A three-dimensional finite element simulation
model is thus developed in this study to simulate the transient temperature distribution and molten
pool dimensions of the premier layer during the SLM of Al-Al2O3 composite powder. In order to
produce high-quality parts with minimum defects in a highly efficient manner, the predicted
optimum volumetric energy density is found to be 40 J/mm3
, with laser power 300 W, scanning
speed 1000 mm/s, hatch spacing 150 μm and layer thickness 50 μm; the molten pool size that is
produced is 165 μm in length, 160 μm in width and 77 μm in depth, with a predicted maximum
temperature of around 3400°C. All of these factors may contribute to the creation of good
metallurgic bonding. | null | null | null | null | null | null |
['Josupeit, Stefan', 'Schmid, Hans-Joachim'] | 2021-10-12T20:05:54Z | 2021-10-12T20:05:54Z | 2014 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88729', 'http://dx.doi.org/10.26153/tsw/15663'] | eng | 2014 International Solid Freeform Fabrication Symposium | Open | ['polymer laser sintering', 'laser sintering', 'temperature measurement', 'part cakes', 'job parameters'] | Three-Dimensional In-Process Temperature Measurement of Laser Sintered Part Cakes | Conference paper | https://repositories.lib.utexas.edu//bitstreams/03dd299f-6ebd-4055-a79f-bb8b98b52a25/download | University of Texas at Austin | An uneven temperature distribution and varying cooling rates at different positions within
the part cake are two of the most important challenges regarding the part quality and reproducibility
of the polymer laser sintering process. In the presented work, a temperature measurement system
is implemented within an EOSINT P395 laser sintering system. It allows the determination of a
three dimensional temperature distribution and history during the full build and cooling process.
The influence of important job parameters, for example the packing density, job height and layer
thickness, can be figured out. In combination with a finite element simulation of the cooling
process, the temperature measurement will be the basis for optimized process controls. | null | null | null | null | null | null |
['Zhou, Xiangman', 'Zhang, Haiou', 'Wang, Guilan'] | 2021-10-26T18:52:30Z | 2021-10-26T18:52:30Z | 2016 | Mechanical Engineering | null | https://hdl.handle.net/2152/89555 | eng | 2016 International Solid Freeform Fabrication Symposium | Open | ['stacking deposition', 'arc welding based additive manufacturing', 'AWAM', 'arc model', 'metal transport'] | Three-Dimensional Numerical Simulation of Arc and Metal Transport for Stacking Deposition in Arc Welding Based Additive Manufacturing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/184821d5-b907-4e47-a512-6cf25383b202/download | University of Texas at Austin | The stacking deposition in arc welding based additive manufacturing (AWAM) results in complex
surfaces of deposited layer. Therefore the electromagnetic force in molten pool, arc pressure, plasma shear
stress and heat flux on molten pool surface are not the same as the conventional welding. A three-dimensional weak coupling modeling method has been developed to simulate the arc, molten pool dynamic
and droplet impingement of stacking deposition. In the arc model, the molten pool is simplified to be solid
state on the basis of experimentally observed result. The arc is simulated firstly, and then the electromagnetic
force, arc pressure, plasma shear stress and heat flux are extracted and transmitted to metal transport model.
The molten pool morphology of simulated result accords well with experimental result, which indicates that
this weak coupling modeling method is capable of simulating the complex heat and mass transfer behaviors
in AWAM. | null | null | null | null | null | null |
['DeNava, Erick', 'Navarrete, Misael', 'Lopes, Amit', 'Alawneh, Mohammed', 'Contreras, Marlene', 'Muse, Dan', 'Castillo, Silvia', 'MacDonald, Eric'] | 2021-09-23T21:25:21Z | 2021-09-23T21:25:21Z | 9/10/08 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88026', 'http://dx.doi.org/10.26153/tsw/14967'] | eng | 2008 International Solid Freeform Fabrication Symposium | Open | ['rapid prototyping', 'stererolithography', 'direct-write', 'hybrid integration manufacturing', '3D off-axis component placement', '3D off-axis routing'] | Three-Dimensional Off-Axis Component Placement and Routing for Electronics Integration using Solid Freeform Fabrication | Conference paper | https://repositories.lib.utexas.edu//bitstreams/53e0d410-6edb-4355-9919-c7778e2d4dfc/download | null | Traditional placement of transistors in chips and components on printed circuit boards has
been constrained in two dimensions. Routing of electrical signals in these devices has been
extended to two and half dimensions by virtue of additional routing layers which are connected
through vertical vias (i.e. four layer printed circuit boards or CMOS chips with seven layers of
metal routing); however, truly three-dimensional off-axis component placement and routing have
not yet been explored. Solid freeform fabrication provides the means of creating a dielectric
substrate suitable for these electronics with sockets for components and channels for
interconnect. Direct write dispensing of conductive inks or epoxies into these channels has been
reported previously for electronics applications, but was generally confined to two dimensions in
a fashion similar to traditional electronics. The current research describes a demonstration
prototype in which components are placed off-axis to fulfill application requirements (for a
three-dimensional magnetic flux sensor system) and where sections are routed off-axis as well –
all of which provides new levels of design freedom for the implementation of electronics
systems. | null | null | null | null | null | null |
["D'Costa, D.J.", 'Dimovski, S.D.', 'Lin., F.', 'El-Raghy, T.', 'Barsoum, M.W.', 'Sun, W.'] | 2019-09-20T18:16:26Z | 2019-09-20T18:16:26Z | 2000 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/75923', 'http://dx.doi.org/10.26153/tsw/3022'] | eng | 2000 International Solid Freeform Fabrication Symposium | Open | Ductile | Three-Dimensional Printing of Layered Machinable Ductile Carbide 80 | Conference paper | https://repositories.lib.utexas.edu//bitstreams/417b5459-5862-442f-9c3f-32ab6648b621/download | null | Ti3SiC2 carbide represents a new class of ceramics with excellent electrical and mechanical properties. This paper presents our preliminary studying on using 3D printing technique, combining with cold isostatic pressing and sintering processing to prototype Ti3SiC2 carbide components. The basic mechanical, electrical and thermal properties of Ti3SiC2 carbide material will be reviewed. Results in die and mold-free 3D printing processing of Ti3SiC2 carbide prototyping will be reported. The SEM
characterization of the prototypes and the correlation with the processing parameters will be presented | null | null | null | null | null | null |
['Pal, Deepanker', 'Stucker, Brent E.'] | 2021-10-05T19:45:22Z | 2021-10-05T19:45:22Z | 8/22/12 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88419', 'http://dx.doi.org/10.26153/tsw/15358'] | eng | 2012 International Solid Freeform Fabrication Symposium | Open | ['ultrasonic consolidation', 'Al 3003-H18 alloy', 'homogenization', 'pure aluminum'] | Time Homogenization of Al3003 H-18 Foils Undergoing Metallurgical Bonding Using Ultrasonic Consolidation | Conference paper | https://repositories.lib.utexas.edu//bitstreams/93e0052c-3456-4b09-90bb-2184e9982078/download | University of Texas at Austin | A dislocation density based finite element model was formulated and initially validated
using published experimental data for simple shear deformation of a single crystal pure
aluminum and uniaxial tension of bulk polycrystalline Al 3003-H18 alloy. The model was
extended to predict the deformation behavior of 150µm Al 3003-H18 foils undergoing ultrasonic
consolidation (UC). The simulated results were in good agreement with the experimental results
for the evolution of linear weld density and embrittlement due to grain substructure formation. A
novel time homogenization approach has been further formulated which significantly reduces the
computational overhead. The time-homogenization approach uses the Almost Periodic Time
Homogenization (APTH) operator based on an asymptotic Forward-Euler scheme for integrating
the coarse time increments. The computational efficiency is proportional to the ratio of coarse to
fine time scales. | null | null | null | null | null | null |
['Male, J.', 'Tsang, H.', 'Bennett, G.'] | 2018-11-08T18:52:30Z | 2018-11-08T18:52:30Z | 1996 | Mechanical Engineering | doi:10.15781/T2PC2TV4W | http://hdl.handle.net/2152/69900 | eng | 1996 International Solid Freeform Fabrication Symposium | Open | ['3D Systems Stereolithography', 'SLS', 'prototypes'] | A Time, Cost and Accuracy Comparison of Soft Tooling for Investment Casting Produced Using Stereolithography Techniques | Conference paper | https://repositories.lib.utexas.edu//bitstreams/b7afa9d8-028b-4569-a585-538dcb67af79/download | null | Investment casting is increasingly widely used in the production ofmetal prototypes in
conjunction with rapid prototyping (RP) technologies. Some types ofRP models can be used
directly as sacrificial patterns in the casting process, but this can prove costly and time
consuming where a number of castings are required.
Soft tooling such as resin tooling and silicon rubber tooling are used to produce a
number of wax patterns for subsequent casting, using an RP model as the master.
Stereolithography faced tools are starting to be used as in some circumstances they can offer
time savings over other soft tooling methods. This paper aims to compare the costs and times
taken to produce wax patterns for use in investment casting using the different soft tooling
techniques and QuickCastTM build style for use as a casting pattern. | null | null | null | null | null | null |
['Stone, Ronnie F.P.', 'Wang, Junmin', 'Sha, Zhenghui'] | 2024-03-26T22:54:51Z | 2024-03-26T22:54:51Z | 2023 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/124435', 'https://doi.org/10.26153/tsw/51043'] | en_US | 2023 International Solid Freeform Fabrication Symposium | Open | ['autonomous robotics systems', 'mobile robots', 'trajectory and path planning', 'intelligent manufacturing systems', 'swarm manufacturing'] | Time-Optimal Path Planning for Heterogeneous Robots in Swarm Manufacturing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/2f6d8b7c-b246-445f-9c97-d5002488ecf6/download | University of Texas at Austin | Time-optimal path planning is a critical problem in any system employing mobile robots. Much
of the literature on this problem operates under two major assumptions: the environment is static,
and the robots’ effective shapes are constant and discretized either as a circle or a sphere, disregarding the impact of the robot’s orientation on the overall task. These assumptions are restrictive in
swarm manufacturing, where the environment is dynamically changing and manufacturing robots
have geometric constraints for operation. For example, robots can not only move but also change
their effective shapes depending on the parts they carry or the material deposited. These variations can significantly impact the path-planning solution. In this paper, we propose a methodology
to find time-optimal paths in swarm manufacturing while explicitly considering the effective and
changing shapes of mobile robots and the dynamic obstacles surrounding them. | null | null | null | null | null | null |
['Xiong, Yi', 'Van Campen, Anke', 'Van Vlierberghe, Anje', 'Kempen, Karolien', 'Kruth, Jean-Pierre'] | 2021-11-02T20:21:12Z | 2021-11-02T20:21:12Z | 2017 | Mechanical Engineering | null | https://hdl.handle.net/2152/89886 | eng | 2017 International Solid Freeform Fabrication Symposium | Open | ['scan path', 'sliced geometry', 'time-optimal', 'geometry analysis', 'powder bed additive manufacturing'] | Time-Optimal Scan Path Planning Based on Analysis of Sliced Geometry | Conference paper | https://repositories.lib.utexas.edu//bitstreams/115d8c44-8b10-4e2b-a341-bbaed0c44921/download | University of Texas at Austin | In powder-bed based layered manufacturing, a focused and high power laser beam is guided
to travel through pre-defined trajectories with various process parameters such as the scan
speed, laser power, and beam diameter to consolidate powdered materials together. The predefined path, therefore, plays a significant role not only on the build part quality but also on
the build time. Current path planning strategies are defined only on the layer level. Although,
contours on one layer can be significantly different in the geometry shape. This paper proposes
an adaptive scan path planning method based on the geometric characteristic of contours. With
this approach, the user is able to control and optimize the scan path for contours with different
geometric types. An algorithm for determining the scanning direction to minimize the build
time is discussed in detail. A path planning approach for non-productive paths illustrates the
potential time gain applying more intelligent strategies. | null | null | null | null | null | null |
['Xu, Changxue', 'Zhang, Zhengyi', 'Fu, Jianzhong', 'Huang, Yong', 'Markwald, Roger R.'] | 2021-10-07T17:54:20Z | 2021-10-07T17:54:20Z | 2013 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88495', 'http://dx.doi.org/10.26153/tsw/15429'] | eng | 2013 International Solid Freeform Fabrication Symposium | Open | ['inkjetting formation', 'alginate solution', 'droplet formation', 'organ printing'] | Time-Resolved Study of Droplet Formation Process During Inkjetting of Alginate Solution | Conference paper | https://repositories.lib.utexas.edu//bitstreams/cb374f78-5550-439e-82fe-d3d9dfd0b795/download | University of Texas at Austin | Organ printing offers a great potential for the fabrication of three-dimensional (3D) living
organs by precisely layer-by-layer placing various tissue spheroids. Such fabricated organs may
replace some damaged or injured human organs, emerging as a promising solution to the
problem of organ donor shortage. As one of the key enabling technologies for organ printing,
inkjetting has been received much attention recently. It is of great importance to understand the
jetting and droplet formation processes during the inkjetting of typical biomaterials such as
alginate solution. The jetting behavior and breakup time during alginate inkjetting have been
studied using a time-resolved approach, and different pinch-off behaviors are classified. The
resulting knowledge will help better promote the inkjetting-based organ printing technology. | null | null | null | null | null | null |
['Harlan, Nicole', 'Bourell, David', 'Beaman, Joe'] | 2019-02-26T20:57:07Z | 2019-02-26T20:57:07Z | 1998 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/73501', 'http://dx.doi.org/10.26153/tsw/651'] | eng | 1998 International Solid Freeform Fabrication Symposium | Open | ['SLS', 'casting environments'] | Titanium Casting Molds via Selective Laser Sintering | Conference paper | https://repositories.lib.utexas.edu//bitstreams/fecde00c-2448-43d9-ac15-869ddbb9770c/download | null | A mold material system has been developed that can be SLS processed and used to
cast titanium alloys. Stabilized zirconia, chosen forits low reactivity with molten titanium,
has been sintered into mold shapes. The molds have been infiltrated with a colloidal
solution ofunstabilized zirconia and fired to create a partially stabilized structure. ·SEM
analysis shows that the unstabilized zirconia forms bridges between the larger stabilized
zirconia particles that provide strength to the mold. | null | null | null | null | null | null |
['Broek, Han J.', 'Horváth, Imre', 'Smit, Bram de'] | 2019-09-23T16:59:01Z | 2019-09-23T16:59:01Z | 2000 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/75971', 'http://dx.doi.org/10.26153/tsw/3070'] | eng | 2000 International Solid Freeform Fabrication Symposium | Open | Flexible | Tool Path Generation for Flexible Blade Cutting | Conference paper | https://repositories.lib.utexas.edu//bitstreams/9ec1dd1d-0224-4b10-b076-5d737ff81f0f/download | null | Free Form Thick Layered Object Manufacturing FF-TLOM is based on application of a reshapeable cutting device, which allows a free form shaping of thick polystyrene foam layers. Once manufactured, these layers are stacked to produce a physical model. Tool path generation for the heated flexible blade tool is a challenging task, since it influences the quality of the manufactured objects as well as the effectiveness of the fabrication process. Them difficulties arise from the following facts: (a) when slicing is computed, the instantaneous tool positions are defined by matching the blade profile against the nominal shape of the CAD
model, (b) the tool positions calculated relative to the cut layers have to be converted into the global reference frame of the layer cutting equipment, (c) the resultant tool path should maintain the achieved preciseness approximating the front surface of the layers, and (d) it is impossible to calculate all points of the tool path in real time. This paper proposes an effective tool path calculation method for flexible blade cutting. The contour of the layers is converted into an ordered set of smooth and awkward boundary features. For the smooth boundary features, the tool positions are computed by dense sampling in order to achieve the optimal cutting. | null | null | null | null | null | null |
['Leite, M.', 'Cunha, J.', 'Sardinha, M.', 'Soares, B.', 'Reis, L.', 'Ribeiro, A.R.'] | 2021-11-15T22:22:22Z | 2021-11-15T22:22:22Z | 2018 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90293', 'http://dx.doi.org/10.26153/tsw/17214'] | eng | 2018 International Solid Freeform Fabrication Symposium | Open | ['tool path generation', 'tool path', 'hybrid manufacturing', 'additive manufacturing', 'subtractive manufacturing'] | Tool Path Generation for Hybrid Additive Manufacturing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/84e76553-92da-4337-9b91-a0411a5e72c8/download | University of Texas at Austin | This paper presents a new approach to tool path generation for a hybrid additive-subtractive manufacturing
apparatus. The goal is the development of an integrated hybrid process, based on additive and subtractive
manufacturing, to produce complex geometries with continuous fiber reinforced thermoplastics.
The authors propose a novel system that can handle two heads: a filament deposition head and a milling
head. The system allows for additive, subtractive, additive followed by subtractive and additive and subtractive
at each layer.
Due to the use of continuous fiber reinforced thermoplastics the tool path trajectories will be different
depending on part geometry to accrue mechanical properties. To evaluate the proposed strategies, one example
with different features is provided on how to take an .stl file with a final geometry and generate the necessary
adjustments to enable the subtractive process. | null | null | null | null | null | null |
['Lim, Wei Sheng', 'Soh, Gim Song'] | 2024-03-26T23:28:28Z | 2024-03-26T23:28:28Z | 2023 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/124452', 'https://doi.org/10.26153/tsw/51060'] | en_US | 2023 International Solid Freeform Fabrication Symposium | Open | ['wire arc additive manufacturing', 'toolpath'] | Toolpath planning approach for parts with multiple revolving features for wire arc additive manufacturing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/5348a16e-f73a-48bd-988e-d46308737065/download | University of Texas at Austin | In wire arc additive manufacturing, existing toolpath planner for complex 3D shapes such
as propellers and turbines, with multiple revolving features radiating tend to utilize a cylindrical
slicing approach. Such slicing approaches are highly customized, complex, and not readily
available for printing such 3D shapes. In addition, such complicated motion planning requires
coordination between the print head and substrate motion to be synchronized well which can be
difficult to achieve. In this paper, we propose an alternative strategy using planar slicing and
adaptive width contour-based toolpath planner. To achieve this, a two-step approach is proposed
with the substrate and radiating elements treated as separate features. The substrate is printed with
part of the revolving feature, providing a flat surface for the second step to print from. The
approach is applied for a propeller over 0.7m in diameter where a 3D scan is done to compare with
the part model. | null | null | null | null | null | null |
['Crockett, Breanne', 'Borish, Michael'] | 2023-01-26T14:48:49Z | 2023-01-26T14:48:49Z | 2022 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/117310', 'http://dx.doi.org/10.26153/tsw/44191'] | eng | 2022 International Solid Freeform Fabrication Symposium | Open | k-means | Toolpath Planning for Multiple Build Points Using K-Means Clustering | Conference paper | https://repositories.lib.utexas.edu//bitstreams/1c6983c0-115c-4880-bf57-f44a6fb4f88f/download | null | Traditional 3D printers deposit material at one build point at a time, often resulting in
long print times. To reduce print time, 3D printers could increase throughput with parallel
construction at multiple build points. The primary challenge in path planning for parallel
construction is dividing an object between the build points. The object should be divided such
that the workload is balanced, and the individual build areas are discrete. This work proposes a
variation of k-means clustering for object division. The algorithm considers coordinate position
and geometric area as an indicator of workload. This method is demonstrated on several test
models to compare workload across the number of build points. | null | null | null | null | null | null |
['Stern, Michael', 'Bari, Joseph'] | 2021-11-04T20:03:34Z | 2021-11-04T20:03:34Z | 2017 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90017', 'http://dx.doi.org/10.26153/16938'] | eng | 2017 International Solid Freeform Fabrication Symposium | Open | ['topological optimization', 'methdology', 'lightweight metallic mirrors', 'metallic mirrors', 'selective laser melting', 'additive manufacturing'] | Topological Optimization and Methodology for Fabricating Additively Manufactured Lightweight Metallic Mirrors | Conference paper | https://repositories.lib.utexas.edu//bitstreams/1e7c1030-a84c-4c8e-9bbe-6a739464db71/download | University of Texas at Austin | Imaging systems for space and airborne platforms have aggressive Size, Weight and
Power (SWaP) requirements. High quality, lightweight optics help enable these types of
systems. Today typical light weighting techniques are accomplished through removal of
material in the back structure with classical machining and the use of low-density, high-stiffness
materials such as beryllium. We present a novel methodology for generating lightweight
metallic mirrors that are fabricated by growing an additive manufactured blank, fly cutting the
surfaces to be mirrored, and post processing the faces by coating them with electroless nickel and
then diamond turning. This process was used in a case study for the development of a topology
optimized, low-weight and high-stiffness spinning mirror. The mirror was fabricated with
selective laser melting and post processed to deliver optical quality mirror surfaces. | null | null | null | null | null | null |
['Maheshwaraa, Uma', 'Seepersad, Carolyn Conner', 'Bourell, David'] | 2020-03-10T16:27:53Z | 2020-03-10T16:27:53Z | 2007 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/80225', 'http://dx.doi.org/10.26153/tsw/7244'] | eng | 2007 International Solid Freeform Fabrication Symposium | Open | selective laser sintering | Topology Design and Freeform Fabrication of Deployable Structures with Lattice Skins | Conference paper | https://repositories.lib.utexas.edu//bitstreams/421e6fcb-2b65-43bd-b169-b75d75f4d82f/download | null | Solid freeform fabrication is particularly suitable for fabricating customized parts, but it has not
been used for fabricating deployable structures that can be stored in a compact configuration and
deployed quickly and easily in the field. In previous work, lattice structures have been
established as a feasible means of deploying parts. Before fabricating the parts with a selective
laser sintering (SLS) machine and Duraform® Flex material, lattice sub-skins are added
strategically beneath the surface of the part. The lattice structure provides elastic energy for
folding and deploying the structure or constrains expansion upon application of internal air
pressure. In this paper, a procedure is presented for optimizing the lattice skin topology for
improved overall performance of the structure, measured in terms of deviation from desired
surface profile. A ground structure-based topology optimization procedure is utilized, with a
penalization scheme that encourages convergence to sets of thick lattice elements that are
manufacturable and extremely thin lattice elements that are removed from the final structure. A
deployable wing is designed for a miniature unmanned aerial vehicle. A physical prototype of
the optimal configuration is fabricated with SLS and compared with the virtual prototype. | null | null | null | null | null | null |
['Jamalabad, Vikram R.', 'Chard, Jeffrey A.', 'Gasdaska, Charles J.', 'Clancy, Richard B.'] | 2019-02-22T17:50:11Z | 2019-02-22T17:50:11Z | 1998 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/73465', 'http://dx.doi.org/10.26153/tsw/615'] | eng | 1998 International Solid Freeform Fabrication Symposium | Open | ['FDC', 'theffiloplastic'] | Topology Driven Improvement of FDC Build Parameters | Conference paper | https://repositories.lib.utexas.edu//bitstreams/b3065a9a-166a-495d-8774-ce7bb531040c/download | null | The likeliest failure origin for advanced ceramics parts, prepared by fused
deposition, is a void from improper fill. Adequate filling of each cross-section is dependent upon the deposition toolpath. Cross-sectional spaces are conventionally
filled with pre-defined parameters. We propose that adaptive build parameters will
control variations in geometry and property of a part. Voids, overfilling,
incomplete bonding and excess traversing can be suppressed by adjusting the fill
parameters for cross-sectional areas. Improved build parameters and toolpath
allows for faster build time and components ofj full density. Some implementations
are discussed and presented. | null | null | null | null | null | null |
['Rashid, R.', 'Masood, S.H.', 'Ruan, D.', 'Palanisamy, S.', 'Huang, X.', 'Rahman Rashid, R.A.'] | 2021-11-09T19:49:42Z | 2021-11-09T19:49:42Z | 2018 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90145', 'http://dx.doi.org/10.26153/tsw/17066'] | eng | 2018 International Solid Freeform Fabrication Symposium | Open | ['BESO method', 'selective laser melting', 'SLM', 'scanning strategy', 'flexural testing', 'energy absorption'] | Topology Optimisation of Additively Manufactured Lattice Beams for Three-Point Bending Test | Conference paper | https://repositories.lib.utexas.edu//bitstreams/4b8c1c3b-7f59-48ac-a1e2-89da45f4610b/download | University of Texas at Austin | The ability of additive manufacturing to develop parts with complex shapes has
increased the bandwidth of product design. This has facilitated the use of Topology
Optimisation (TO) techniques to optimise the distribution of material throughout the part,
thereby obtaining minimum weight without compromising the mechanical performance of the
component. In this study the Bi-directional Evolutionary Structural Optimisation (BESO)
algorithm was used to generate topologically optimised lattice unit cells. A simple bending
beam with 50% reduced volume was printed in two different unit cell arrangements using
Selective Laser Melting (SLM) process. Prior to printing, the density of SLM-printed AlSi12
samples was enhanced by using appropriate scanning strategy. The flexural properties of these
topology optimised beams were compared with the solid beam. The topologically optimised
beams absorbed about seven times more energy per unit volume till the displacement of
maximum bending load when compared with the solid beam at the same displacement. | null | null | null | null | null | null |
['Fey, Nicholas P.', 'South, Brian J.', 'Seepersad, Carolyn C.', 'Neptune, Richard R.'] | 2021-09-29T17:28:11Z | 2021-09-29T17:28:11Z | 2009-09 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88195', 'http://dx.doi.org/10.26153/tsw/15136'] | eng | 2009 International Solid Freeform Fabrication Symposium | Open | ['prosthetic feet', 'topology optimization', 'selective laser sintering'] | Topology Optimization and Freeform Fabrication Framework for Developing Prosthetic Feet | Conference paper | https://repositories.lib.utexas.edu//bitstreams/fa502765-c495-4630-b973-96d2df978687/download | University of Texas at Austin | The ability to easily design and manufacture prosthetic feet with novel design characteristics
has great potential to improve amputee rehabilitation and care. This study presents a framework
using topology optimization methods to develop new prosthetic feet to be manufactured using
selective laser sintering. As an example application, the framework was used to generate a
prosthetic foot that minimizes material usage while trying to replicate the stiffness characteristics
of a commercially available carbon fiber foot. The solution was validated using finite element
methods to verify the foot’s loading response, and a prototype was manufactured. The result was
a novel foot design that with future design modification has the potential to improve amputee
gait by providing energy storage and return and reducing prosthetic weight. | null | null | null | null | null | null |
['Jiang, D.', 'Smith, D.E.'] | 2021-11-04T19:59:20Z | 2021-11-04T19:59:20Z | 2017 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90016', 'http://dx.doi.org/10.26153/16937'] | eng | 2017 International Solid Freeform Fabrication Symposium | Open | ['3D material distribution', 'non-isotropic material distribution', 'material direction', 'material orientation', 'topology optimization', 'additive manufacturing'] | Topology Optimization for 3D Material Distribution and Orientation in Additive Manufacturing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/67c69f3f-d102-4eb1-b542-68d491abafb3/download | University of Texas at Austin | Products produced with Additive Manufacturing (AM) methods often have anisotropic
microstructure that forms as material layers are added during processing. Unfortunately, current
AM design methods do not accommodate the inherent non-isotropic behavior of these materials
when determining the best structural layout. This paper presents a three dimensional (3D)
topology optimization method that computes the best non-isotropic material distribution and
principal material direction for minimum compliance of a statically loaded non-isotropic AM
structure. The compliance objective function is calculated using the finite element method with
eight node 3D isoparametric elements, and design sensitivities with respect to both density and
material orientation are calculated with the Adjoint Variable method. We employ a linear
weighted sensitivity filter on the density variables to mitigate checker-boarding of the material
distribution. The optimization problem is solved with a nonlinear constraint-based Matlab (The
Mathworks, Inc., Natick, MA) optimization solver. Topology optimization of a 3D cantilever
beam with different print directions is given to demonstrate the applicability of the optimization
scheme. | null | null | null | null | null | null |
['Brackett, D.', 'Ashcroft, I.', 'Hague, R.'] | 2021-10-04T21:52:25Z | 2021-10-04T21:52:25Z | 8/17/11 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88361', 'http://dx.doi.org/10.26153/tsw/15300'] | eng | 2011 International Solid Freeform Fabrication Symposium | Open | ['topology optimization', 'additive manufacturing', 'solid isotropic material with penalization'] | Topology Optimization for Additive Manufacturing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/dd9c4b52-36b4-4a1d-9985-adf0f660ed25/download | University of Texas at Austin | This paper gives an overview of the issues and opportunities for the application of
topology optimization methods for additive manufacturing (AM). The main analysis issues
discussed are: how to achieve the maximum geometric resolution to allow the fine features easily
manufacturable by AM to be represented in the optimization model; the manufacturing
constraints to be considered, and the workflow modifications required to handle the geometric
complexity in the post optimization stages. The main manufacturing issues discussed are the
potential for realizing intermediate density regions, in the case of the solid isotropic material
with penalization (SIMP) approach, the use of small scale lattice structures, the use of multiple
material AM processes, and an approach to including support structure requirement as a
manufacturing constraint. | null | null | null | null | null | null |
['Ramsey, J.S.', 'Smith, D.E.'] | 2021-11-30T19:38:48Z | 2021-11-30T19:38:48Z | 2019 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90524', 'http://dx.doi.org/10.26153/tsw/17443'] | eng | 2019 International Solid Freeform Fabrication Symposium | Open | ['topology optimization', 'material anisotropy', 'thermomechanical loading', 'anisotropic', 'additive manufacturing'] | Topology Optimization for Anisotropic Thermomechanical Design in Additive Manufacturing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/bc2cd8e7-fa60-4a4a-81d2-76e22057badc/download | University of Texas at Austin | Topology optimization has emerged as an effective design approach that obtains complex
geometries suitable for additive manufacturing. However, additively manufactured structures
typically have anisotropic material properties, and residual thermal stresses result from
nonisothermal processes. This paper presents a new topology optimization-based approach that
incorporates both material anisotropy and weakly coupled thermomechanical loading into the
material layout computations. An optimality criterion-based update scheme minimizes
compliance or strain energy of a design space over material density and orientation where special
attention is given to the optimal material orientation computations. The coupled
thermomechanical analysis and material direction optimization reflects the anisotropic Young’s
modulus and thermal stresses present in large-scale polymer deposition. Resultant structures
show how thermal loading influences the optimal topology, and how different penalty values
determine convergence of the design. | null | null | null | null | null | null |
['Torries, Brian', 'DorMohammadi, Saber', 'Abdi, Frank', 'Thompson, Scott', 'Shamsaei, Nima'] | 2021-11-04T20:07:08Z | 2021-11-04T20:07:08Z | 2017 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90018', 'http://dx.doi.org/10.26153/16939'] | eng | 2017 International Solid Freeform Fabrication Symposium | Open | ['additive manufacturing', 'topology optimization', 'defects distribution', 'porosity', 'ICME'] | Topology Optimization of an Additively Manufactured Beam | Conference paper | https://repositories.lib.utexas.edu//bitstreams/027e0a3c-229b-4589-bbc7-e51f5a04fc28/download | University of Texas at Austin | This study investigates the application of topological optimization in conjunction with additive
manufacturing (AM) process simulation for fabricating parts that meet strict quality and
performance requirements while also minimizing printed geometry. Integrated Computational
Materials Engineering (ICME) and GENOA 3D commercial software were used to simulate
specimen fabrication and, along with commercial design optimization tools, create an optimized
beam topology for simple loading conditions. Constraints were set in order to support any overhanging material with an appropriate inclination angle. These specimens were fabricated from Ti-6Al-4V using an EOS M290 direct metal laser sintering (DMLS) system with default parameters,
as well as 95%, 90%, and 88% of default laser power in order to reduce the porosity in the overheated areas. Parts were subjected to X-ray CT scanning to quantify part porosity. It was
determined that the process used allowed for the fabrication of specimens with optimized topology
and minimal defects. | null | null | null | null | null | null |
['Menge, Dennis', 'Delfs, Patrick', 'Töws, Marcel', 'Schmid, Hans-Joachim'] | 2021-11-09T19:58:18Z | 2021-11-09T19:58:18Z | 2018 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90148', 'http://dx.doi.org/10.26153/tsw/17069'] | eng | 2018 International Solid Freeform Fabrication Symposium | Open | ['heat transfer', 'topology optimization', 'electronic housing', 'AlSi10Mg', 'selective laser melting'] | Topology Optimized Heat Transfer Using the Example of an Electronic Housing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/e926114a-2083-4402-9dfd-11e678222c02/download | University of Texas at Austin | Function integration is a key issue for an efficient and economic usage of Additive
Manufacturing. An efficient heat transfer by topology optimized structures is a rarely considered
approach which will be outlined with an exemplary electronic housing which has been newly
designed. A commercial projector unit, whose electrical components in total produce 38 W, shall
be integrated in the closed housing and passively cooled by natural convection. Topology
optimized structures shall be generated in the inner part of the housing to transfer the heat
homogenously from the projector components to the housing wall while simultaneously
minimizing the mass. At the outside of the housing walls, lattice and rib structures are applied to
increase the effective surface for heat transfer by natural convection and radiation. Furthermore,
the housing geometry is optimized regarding a minimization of support structures to reduce the
post-processing effort. Finally, the housing shall be built of AlSi10Mg by SLM. | null | null | null | null | null | null |
Wasserfall, Florens | 2021-11-11T16:26:03Z | 2021-11-11T16:26:03Z | 2018 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90236', 'http://dx.doi.org/10.26153/tsw/17157'] | eng | 2018 International Solid Freeform Fabrication Symposium | Open | ['3D printed electronics', 'multi-material manufacturing', 'routing', 'slicing'] | Topology-Aware Routing of Electric Wires in FDM-Printed Objects | Conference paper | https://repositories.lib.utexas.edu//bitstreams/1333dab0-4ad7-4a36-9558-a9cb57a29e65/download | University of Texas at Austin | The direct integration of electric connections into AM-fabricated plastic parts at printing time has
recently attracted increasing attention. To make efficient use of such techniques, appropriate design
and routing software is required. In prior work, we proposed the integration of Surface-Mounted
Devices (SMD) and wiring into a slicing-software for FDM-based processes. This approach allows to consider process parameters, e.g. extrusion width, layer thickness or temperature for each
specific printjob. In this work, we introduce an algorithm for local, topology-aware wire routing.
The trace-width of a printed wire roughly equates the typical extrusion width of FDM-printers and
the pitch of larger SMD-package types. For curved object surfaces and regions with high wire density, linear routing produces a high number of small islands and gaps. To mitigate this effect, we
attempt to align wires with object perimeters and perimeters of already routed wires. A weighted
graph representation is generated from all printable perimeters of each layer and direct connections
between wire waypoints. An A*-based search is then employed to find optimal routes. | null | null | null | null | null | null |
['Jung, Jinho', 'Chen, Yong'] | 2021-09-30T20:18:54Z | 2021-09-30T20:18:54Z | 2010 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88295', 'http://dx.doi.org/10.26153/tsw/15236'] | eng | 2010 International Solid Freeform Fabrication Symposium | Open | ['reverse engineering', 'Wiimote CAD', '3D modeling', 'augmented reality'] | Touch-RE: A Touch-based Model Acquiring Method for Personal Manufacturing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/31494163-9133-47a0-8b21-175dde992d66/download | University of Texas at Austin | Enabled by additive manufacturing technology, personal manufacturing, if realized, will give
ordinary people control over their physical world by allowing them to personally program its construction.
Currently several pioneering mass customization and personal fabrication applications have been
developed for consumer products, gifts, toy, etc. However, one of the core challenges that are remained to
be addressed for realizing personal manufacturing is the easiness of creating 3D models for additive
manufacturing systems. Current developments in CAD software and reverse engineering are still lacking
on the easiness of usage especially for normal users without much experience. In this paper, we present a
touch-based 3D-shape acquiring method that is easy and intuitive to use. The key technical challenges on
the related hardware and software development are discussed. A testbed system is presented and multiple
examples are given to demonstrate its capability. | null | null | null | null | null | null |
['Araújo, L.J.P.', 'Özcan, E.', 'Atkin, J.A.D.', 'Baumers, M.', 'Tuck, C.', 'Hague, R.'] | 2021-10-19T20:54:45Z | 2021-10-19T20:54:45Z | 2015 | Mechanical Engineering | null | https://hdl.handle.net/2152/89337 | eng | 2015 International Solid Freeform Fabrication Symposium | Open | ['Additive Manufacturing', 'packing', 'build volumes', 'benchmarks'] | Toward Better Build Volume Packing in Additive Manufacturing: Classification of Existing Problems and Benchmarks | Conference paper | https://repositories.lib.utexas.edu//bitstreams/fd3a00dd-5a9a-4fac-abea-b17fc8f6be17/download | University of Texas at Austin | In many cases, the efficient operation of Additive Manufacturing (AM) technology relies on build volumes
being packed effectively. Packing algorithms have been developed in response to this requirement. The
configuration of AM build volumes is particularly challenging due to the multitude of irregular geometries
encountered and the potential benefits of nesting parts. Currently proposed approaches to address this packing
problem are routinely evaluated on data sets featuring shapes that are not representative of targeted manufacturing
products. This study provides a useful classification of AM build volume packing problems and an overview of
existing benchmarks for the analysis of such problems. Additionally, this paper discusses characteristics of future,
more realistic, benchmarks with the intention of promoting research toward effective and efficient AM build
volume packing being integrated into AM production planning methodologies. | null | null | null | null | null | null |
['Narra, Sneha P.', 'Cunningham, Ross', 'Christiansen, Daniel', 'Beuth, Jack', 'Rollett, Anthony D.'] | 2021-10-20T21:22:10Z | 2021-10-20T21:22:10Z | 2015 | Mechanical Engineering | null | https://hdl.handle.net/2152/89364 | eng | 2015 International Solid Freeform Fabrication Symposium | Open | ['Electron Beam Melting', 'process parameters', 'melting', 'grain size', 'Ti-6Al-4V'] | Toward Enabling Spatial Control of Ti-6Al-4V Solidification Microstructure in the Electron Beam Melting Process | Conference paper | https://repositories.lib.utexas.edu//bitstreams/151a00a7-9d12-44ce-8e0c-96b8d394325f/download | University of Texas at Austin | In this work, relationships between prior beta grain size in solidified Ti-6Al-4V and melting
process parameters in the Arcam Electron Beam Melting (EBM) process are investigated. Toward
this goal, samples are built on an Arcam S12 machine at Carnegie Mellon University by
specifically varying the Arcam proprietary speed function and beam current over process space
for a variety of test specimens. Optical microscopy is used to measure the prior beta grain widths
and assess the number of prior beta grains present in a melt pool in the raster region of the build.
Results demonstrate that the number of grains across the width of a bead is constant for a fixed
deposition geometry. The resulting understanding of the relationship between primary machine
variables and prior beta grain widths is a key step toward understanding and enabling the spatial
control of as-built microstructure in the EBM process. | null | null | null | null | null | null |
['Sachs, Emanuel', 'Polito, Benjamin', 'Ables, David', 'Cima, Michael', 'Tsuchiya, Hiroyasu', 'Enokido, Yasushi'] | 2019-09-23T15:34:25Z | 2019-09-23T15:34:25Z | 2000 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/75938', 'http://dx.doi.org/10.26153/tsw/3037'] | eng | 2000 International Solid Freeform Fabrication Symposium | Open | Components | Toward Manufacturing of Fine Components by 3D Printing 191 | Conference paper | https://repositories.lib.utexas.edu//bitstreams/8956efc2-cac2-4ca0-92c7-daf225897ea9/download | null | Solid Freeform Fabrication has earned its place in the industrial practice of prototyping and is beginning to have an impact in the fabrication of tooling. The next and perhaps greatest opportunity for SFF lies on the direct manufacture of components. This paper will present efforts directed toward the MANUFACTURE IN HIGH QUANTITY of small, precision components by 3D Printing. The primary focus is on ceramic and ceramic/metal components, although all metal components are envisioned as well. The production of small, fine-featured parts presents two opportunities for a new machine architecture. First, the powderbeds required for small parts are themselves small and lightweight. Thus, a machine can be designed where powderbeds move from the layer spreading station to the print station and back again. Multiple powder beds can be in play, taking full advantage of all stations of the machine. The second opportunity is to define the perimeter of the part using vector motions of a nozzle with the interior filled by raster scanning. Such an approach has the advantage that the boundary of the part will be defined as a smooth contour. Moving powderbeds and vector printing are combined in the linear shuttle-type machine for research purposes. Ultimately, a rotary machine is envisioned for high production. | null | null | null | null | null | null |
['Gomez Bonilla, Juan S.', 'Trzenschiok, Holger', 'Lanyi, Franz', 'Schubert, Dirk W.', 'Bück, Andreas', 'Schmidt, Jochen', 'Peukert, Wolfgang'] | 2021-11-18T16:42:19Z | 2021-11-18T16:42:19Z | 2019 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90421', 'http://dx.doi.org/10.26153/tsw/17342'] | eng | 2019 International Solid Freeform Fabrication Symposium | Open | ['plasma enhanced chemical vapor deposition', 'PECVD', 'silica nanoparticles', 'bed coating', 'flow behavior', 'processability', 'polypropylene', 'selective laser sintering'] | Toward Modification of Flow Behavior and Processability of Polypropylene Powders in SLS by Fluidized Bed Coating with In-Situ Plasma Produced Silica Nanoparticles | Conference paper | https://repositories.lib.utexas.edu//bitstreams/170ceeaa-18cd-4c1e-b192-069201a18e40/download | University of Texas at Austin | The processability of selective laser sintering (SLS) powders and the characteristics of the generated parts
depend amongst others on the flowability. To increase the flowability, SLS powders are usually functionalized
with flowing agents. Flowing agents are typically applied by dry particle coating. The optimization of the process
parameters necessary to achieve a homogenous coating avoiding segregation is still empirical. In this contribution,
an alternative process to particle dry coating is presented. This process integrates the synthesis of silica
nanoparticles via plasma enhanced chemical vapor deposition (PECVD) and coating of polymer host particles in
a fluidized bed in a single process. The influence of the treatment time on the packing density and flow behavior
of the powders is investigated. Test specimen are produced to assess the influence of the treatment on the
processability of the powders and the mechanical properties of the produced parts. | null | null | null | null | null | null |
['Yeung, Ho', 'Neira, Jorge'] | 2024-03-26T22:56:31Z | 2024-03-26T22:56:31Z | 2023 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/124436', 'https://doi.org/10.26153/tsw/51044'] | en_US | 2023 International Solid Freeform Fabrication Symposium | Open | ['laser bed powder fusion', 'additive manufacturing', 'voxel level control'] | Toward Voxel Level Control for Laser Powder Bed Fusion Additive Manufacturing Processes | Conference paper | https://repositories.lib.utexas.edu//bitstreams/6ca02980-4d42-4d59-94c1-bd8cb655d33b/download | University of Texas at Austin | In the Laser Powder Bed Fusion (LPBF) additive manufacturing (AM) process, a highspeed scanning laser beam is employed to construct components by melting and fusing metal
powder together. While AM is generally characterized as a layer-by-layer technique, LPBF builds
can also be conceptualized on a voxel-by-voxel basis, utilizing a point laser heating source. As a
result, managing the LPBF process at the voxel level – that is, focusing on individual 3D printing
elements or volume pixels – will be highly beneficial. In this study, we will explore the laser
control requirements necessary for achieving voxel-level precision in the LPBF process and
demonstrate these concepts through experiments. | null | null | null | null | null | null |
['Abdullahi, Adnan', 'Kankam, Immanuella', 'Gahloth, Abhay Singh', 'Arora, Bhavya', 'Agarwal, Ankit', 'Eppley, Trevor', 'Salti, Ziyad', 'Goss, Derek', 'Sharma, Raghav', 'Bhate, Dhruv'] | 2021-11-18T02:06:06Z | 2021-11-18T02:06:06Z | 2019 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90407', 'http://dx.doi.org/10.26153/tsw/17328'] | eng | 2019 International Solid Freeform Fabrication Symposium | Open | ['3D printing', 'composite', 'carbon fiber', 'micromechanics', 'additive manufacturing', 'modeling'] | Towards a Micromechanics Model for Continuous Carbon Fiber Composite 3D Printed Parts | Conference paper | https://repositories.lib.utexas.edu//bitstreams/3e7cd553-98b1-4661-a32c-b9740d542b27/download | University of Texas at Austin | Material extrusion is transitioning from a technology mainly for rapid prototyping to one that
is increasingly finding use in manufacturing functional parts. Of particular interest in this regard
is the reinforcement of extruded parts with Continuous Carbon Fiber (CCF). However, predicting
the effective properties of 3D printed composite parts presents a unique challenge because of the
strong effects of meso-structure on the mechanical behavior of printed parts. This work aims to
develop a mathematical model that would enable such a prediction of behavior by incorporating
the rule of mixtures commonly used in micromechanics modeling. Results from tensile tests on
composite specimens with varying volume fractions produced from a blend of onyx (nylon and
chopped carbon fiber) and CCF are reported. Volume fractions are varied through a range of
factors including the layers with fiber, the distribution of fiber within layers and the angle of the
fibers relative to the loading direction, though findings suggest that this has no significant influence
on the model itself, and that volume fraction is a sufficient parameter. The predictive ability of the
micromechanics model is put to the test for composite honeycombs under compression, and a wide
discrepancy between model and experimental result is demonstrated, demonstrating the limitations
of such a model and suggesting pathways for improvement. | null | null | null | null | null | null |
['Mai, J.', 'Thistleton, C.', 'Löschke, S.K.', 'Proust, G.', 'Dong, A.'] | 2021-10-28T22:40:02Z | 2021-10-28T22:40:02Z | 2016 | Mechanical Engineering | null | https://hdl.handle.net/2152/89720 | eng | 2016 International Solid Freeform Fabrication Symposium | Open | ['wood-plastic composites', 'fused deposition modeling', 'aesthetic', 'perlin noise'] | Towards a New Techno-Aesthetic Paradigm: Experiments with Pattern, Texture and Colour in 3D-Printed Wood-Plastic Composites | Conference paper | https://repositories.lib.utexas.edu//bitstreams/ff66de6e-055c-4dc8-9fb8-2f38977f7cd0/download | University of Texas at Austin | 3D printing of wood-plastic composites (WPC) has the potential to create its own
aesthetic paradigm by taking advantage of the possibilities of digital fabrication. This study
explores the process parameters affecting the aesthetic of the resultant 3D printed product using
the commercial wood-plastic composite filament LAYWOO-D3, and printed using a Leapfrog™
Creatr 1.75mm fused deposition modelling (FDM) system. The parameters explored were the
temperature of the printer nozzle of the 3D printer, the velocity of the printer head and the
toolpath of the extruder. These variables were manipulated with algorithms to incorporate key
aesthetic attributes of wood such as the grain pattern, surface texture and colour. Study of these
parameters will allow further insight into the creation of 3D printed wood-plastic composites and
has the potential to forge a positive public perception of composites as a technologically
advanced product that offers a functional and aesthetic alternative to natural wood. | null | null | null | null | null | null |
['Mazzei Capote, G.A.', 'Redmann, A.', 'Koch, C.', 'Rudolph, N.'] | 2021-11-02T18:17:20Z | 2021-11-02T18:17:20Z | 2017 | Mechanical Engineering | null | https://hdl.handle.net/2152/89856 | eng | 2017 International Solid Freeform Fabrication Symposium | Open | ['3D printing', 'FFF', 'tensile properties'] | Towards a Robust Production of FFF End-User Parts with Improved Tensile Properties | Conference paper | https://repositories.lib.utexas.edu//bitstreams/82c519fc-dbd0-492b-a744-505a770dc44e/download | University of Texas at Austin | The relatively low cost of Fused Filament Fabrication (FFF) printers and wide variety of
materials -spanning multiple functionalities and prices- make this process interesting for
production of functional parts. However, FFF produced objects underperform in terms of
mechanical properties when compared to injection molding. Therefore, a study of tensile
properties of FFF produced parts was conducted according to the ASTM D-638 standard, using a
commercial and an in-house produced ABS filament. Initial tests using commercial ABS revealed
poor reproducibility of results, which were analyzed in detail in this study. This led to designing a
formal bed levelling procedure for the printer, evaluating effects of printer configuration and
material quality as well as exploring modifications to the ASTM test procedure. As a result, test
specimens with properties close to injection molding parts were produced. Therefore, the different
impact factors will be discussed and the new procedures will be presented. | null | null | null | null | null | null |
['Lindemann, Christian', 'Jahnke, Ulrich', 'Reiher, Thomas', 'Koch, Rainer'] | 2021-10-18T20:37:04Z | 2021-10-18T20:37:04Z | 2014 | Mechanical Engineering | null | https://hdl.handle.net/2152/89237 | eng | 2014 International Solid Freeform Fabrication Symposium | Open | ['additive manufacturing', 'end users', 'part candidates', 'business integration'] | Towards a Sustainable and Economic Selection of Part Candidates for Additive Manufacturing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/906475bf-fbed-4f14-9825-c8aa247fdea3/download | University of Texas at Austin | Additive manufacturing has a high potential for improving time and cost efficiency as well as
functionality of products in many branches. Today potential users struggle with the
integration of this technology in their businesses. The production costs of this technology
often seem too high compared to traditionally manufactured parts and many users seem
disappointed with the performance of the technology. One of the crucial points for bringing
the technology to new users and new industries is the appropriate selection of feasible part
candidates. A systematic selection of parts is crucial for the sustainable and successful use
and integration of additive manufacturing into existing businesses. The selection needs to be
based on technical, economical and strategic aspects. This paper presents a methodology to
help end users to find appropriate part candidates, which are capable of bringing AM into
their businesses. The concept furthermore includes approaches for redesigning current
available parts and helps to estimate the economic implications of the use of the technology. | null | null | null | null | null | null |
['Kerr, C.J.', 'Munguia Valenzuela, J.', 'Nixon-Pearson, O.', 'Forrest, M.', 'Gosling, P.D.'] | 2023-04-03T15:32:56Z | 2023-04-03T15:32:56Z | 2022 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/117715', 'http://dx.doi.org/10.26153/tsw/44594'] | eng | 2022 International Solid Freeform Fabrication Symposium | Open | ['Polymers', 'Pastes', 'Extrusion', 'UV Curing', 'Processing', 'Large Area Additive Manufacturing', 'Composites', 'Standards', 'Flexural Testing'] | Towards an Automated Methodology for Optically Cured, High Thickness Composite Polymer Pastes: An Iso-based Approach for Large Area Additive Manufacturing | Conference paper | https://repositories.lib.utexas.edu//bitstreams/16514b8e-d950-4ff7-afdc-9d82ac8c8127/download | null | Optically cured polymer composites can offer numerous advantages over thermally-
processed composites. This is especially applicable with large beads generated using Large
Area Additive Manufacturing (LAAM) extrusion. This paper proposes a low-cost, semi-
automated, off-the-shelf desktop system to quickly and precisely cure 8 mm thick, glass-filled
(di-)methacrylate composite specimens for three-point flexural testing. In the absence of a
clear preparation method for specimens of this thickness, we integrate aspects of two existing
ISO Standards: ISO 178:2019, and ISO 4049:2019, to provide a rapid and reliable basis for
specimen preparation and flexure testing. We propose two distinct curing strategies and
compare these in terms of the flexural performance of prepared specimens, and the total cure
time. Flexural data is critical to understanding the structural performance of light-activated
composite pastes; and the curing methodology can be applied to potential future technologies
which involve high-speed in-situ curing, from direct part/feature repair to functional
production. | null | null | null | null | null | null |
['Dantin, Matthew J.', 'Furr, William M.', 'Priddy, Matthew W.'] | 2021-11-15T21:04:58Z | 2021-11-15T21:04:58Z | 2018 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90271', 'http://dx.doi.org/10.26153/tsw/17192'] | eng | 2018 International Solid Freeform Fabrication Symposium | Open | ['additive manufacturing', 'directed energy deposition', 'open-source', 'G-code', 'finite element modeling'] | Towards an Open-Source, Preprocessing Framework for Simulating Material Deposition for a Directed Energy Deposition Process | Conference paper | https://repositories.lib.utexas.edu//bitstreams/b8afaca7-2ee4-49b9-8459-0f9b60253c82/download | University of Texas at Austin | This work focuses on the development of an open-source framework to simulate material
deposition for arbitrary geometries with respect to desired process parameters during a directed
energy deposition (DED) process. This framework allows the flexibility to define the element
activation criteria used in conjunction with Abaqus. A Python script was developed to extract
toolpath coordinates from G-code and implement an element activation sequence that is unique to
a specific CAD drawing. This is important for simulating the additive manufacturing construction
of complex geometries because the thermal history of the component is dependent on laser path,
which has a significant effect on residual stresses and distortion. The results of varying the element
activation criteria are compared with simulated temperature profiles. | null | null | null | null | null | null |
['Urban, James', 'Capps, Nick', 'West, Brian', 'Hartwig, Troy', 'Brown, Ben', 'Landers, Robert', 'Bristow, Douglas', 'Kinzel, Edward'] | 2021-11-08T21:38:15Z | 2021-11-08T21:38:15Z | 2017 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90048', 'http://dx.doi.org/10.26153/tsw/16969'] | eng | 2017 International Solid Freeform Fabrication Symposium | Open | ['defect detection', 'defects', 'fingerprinting', 'modal testing', 'metal parts', 'selective laser melting'] | Towards Defect Detection in Metal SLM Parts Using Modal Analysis "Fingerprinting" | Conference paper | https://repositories.lib.utexas.edu//bitstreams/527b11b1-c3fa-4c35-9958-3d1b7513ae86/download | University of Texas at Austin | The validation of Additively Manufactured (AM) materials is a difficult and expensive
process because the local engineering properties are a function of the thermal history. The thermal
history varies with the process parameters, as well as the part geometry. This paper presents a case
study using modal testing to identify defects in realistic AM parts. A setup consisting of a
Scanning Laser Doppler Vibrometer (LDV) was used to identify the resonant frequencies for
several geometrically identical parts on a build plate. Parts with suboptimal process parameters
from purposely varying the process parameters, are identified by a shift in the mode peak
frequency. Results from this study are compared to Finite Element Analysis (FEM) models and
generalized for identifying defects in parts created with AM on the basis vibration/modal
“fingerprinting.” | null | null | null | null | null | null |
['Kurfess, Rebecca', 'Saleeby, Kyle', 'Feldhausen, Thomas', 'Fillingim, Blane', 'Hart, A. John', 'Hardt, David'] | 2023-01-25T14:02:14Z | 2023-01-25T14:02:14Z | 2022 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/117286', 'http://dx.doi.org/10.26153/tsw/44167'] | eng | 2022 International Solid Freeform Fabrication Symposium | Open | ['directed energy deposition', 'support structures', 'porosity'] | Towards directed energy deposition of metals using polymer-based supports: porosity of 316L stainless steel deposited on carbon-fiber-reinforced ABS | Conference paper | https://repositories.lib.utexas.edu//bitstreams/b28f9f15-eeb8-43e1-9ae7-219e2fb5d143/download | null | Directed energy deposition (DED) is increasingly valuable to many industries because of
its high deposition rates relative to other metal additive manufacturing processes, but the design
space of DED is limited. For instance, steep overhangs are difficult or impossible to manufacture.
Polymer-based support structures could help address this challenge. The viability of DED on
polymer composite substrates has begun to be explored, specifically with 316L stainless steel on
carbon-fiber-reinforced ABS substrates. Monolithic metal components can be deposited on the
polymer, but it was found that gas release during polymer degradation causes porosity due to gas
entrapment in the metal. An interlayer cooling time was introduced to reduce polymer degradation
and decrease the porosity due to gas entrapment, but this led to porosity from lack of fusion. The
results of this work provide insight into process parameter selection and scan strategy development
to enable the use of polymer support structures in blown-powder DED. | null | null | null | null | null | null |
['Jahn, A.', 'Li, H.', 'Emminghaus, N.', 'Melnyk, T.', 'Hermsdorf, J.', 'Kaierle, S.'] | 2024-03-27T16:02:01Z | 2024-03-27T16:02:01Z | 2023 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/124498', 'https://doi.org/10.26153/tsw/51106'] | en | 2023 International Solid Freeform Fabrication Symposium | Open | ['additive manufacturing', 'Ti-6Al-4V', 'laser powder bed fusion', 'gyroids', 'porosity'] | Towards experimental process parameter development for Ti-6Al-4V TPMS lattice structures with application to small scale dental implants using micrographs | Conference paper | https://repositories.lib.utexas.edu//bitstreams/c23d7d2a-92cb-4390-a464-cdb8c7afb76a/download | University of Texas at Austin | Ti-6Al-4V is a widely used alloy in implant engineering and lattice structures can be applied to locally
match the stiffness of the implant to the stiffness of bone. Triply periodic minimal surface (TPMS) structures are
popular due to their curved surface, which supports a good manufacturability and osseointegration of the implant.
Tests with different TPMS structures showed a strong interaction between design factors and manufacturing
parameters resulting in the need for individual parameter development. However, to the best of our knowledge,
the most work in the current literature focusses on mechanical and biological examinations of TPMS structures
manufactured with standard parameters. As process parameters influence the structural properties, the optimum
values for further analysis may not have been investigated (e.g., their influence on microstructure and mechanical
properties). In this work, a design of experiments approach is used to develop process parameters. As computer
tomography scans are resource intensive for large scale parameter development, a sparser approach using
micrographs for porosity analysis is introduced. Small structures with unit cell size as small as 1.0 mm are
fabricated on a laser powder bed fusion industrial machine. Our initial studies show that the design factor pore
size is negligible in comparison to wall thickness when optimizing internal porosity. | null | null | null | null | null | null |
['Kniepkamp, Michael', 'Harbig, Jana', 'Seyfert, Christoph', 'Abele, Eberhard'] | 2021-11-15T22:45:21Z | 2021-11-15T22:45:21Z | 2018 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/90301', 'http://dx.doi.org/10.26153/tsw/17222'] | eng | 2018 International Solid Freeform Fabrication Symposium | Open | ['layer thickness', 'combination', 'build rates', 'selective laser melting'] | Towards High Build Rates: Combining Different Layer Thickness within One Part in Selective Laser Melting | Conference paper | https://repositories.lib.utexas.edu//bitstreams/01dbd4af-e92d-4272-a148-b9b6b0432d06/download | University of Texas at Austin | Additive manufacturing of metallic parts using powder bed based fusion processes like
selective laser melting is increasingly used in industrial applications. With typical layer thicknesses
of 20 – 40 µm good surface qualities and high geometrical accuracy can be achieved compared to
other AM processes. However, low layer thicknesses are to the detriment of build rates as more
layers are required. Increasing the layer thickness can significantly increase build rates at the cost
of surface quality and accuracy. In this paper a new parameter set for a layer thickness of 60 µm is
developed and combinations of different layer thicknesses within one part are investigated. Thus
increased build rates can be achieved while a high accuracy can be maintained when locally
required. Specimens with combination of different layer thicknesses in various build orientations
are produced and mechanically tested. Micrographs of the layer transitions are examined and
recommendations for their design are given. | null | null | null | null | null | null |
['Yan, Wentao', 'Ge, Wenjun', 'Smith, Jacob', 'Wagner, Gregory', 'Lin, Feng', 'Kam Liu, Wing'] | 2021-10-19T22:01:42Z | 2021-10-19T22:01:42Z | 2015 | Mechanical Engineering | null | https://hdl.handle.net/2152/89343 | eng | 2015 International Solid Freeform Fabrication Symposium | Open | ['Electron Beam Melting', 'Finite Element Method', 'high quality', 'single track formations', 'distortions'] | Towards High-Quality Selective Beam Melting Technologies: Modeling and Experiments of Single Track Formations | Conference paper | https://repositories.lib.utexas.edu//bitstreams/bb8e3205-301d-4dc1-a17e-815bb57b01b6/download | University of Texas at Austin | Additive manufacturing technologies are promising but still not widely used. One major
problem is the unsatisfying quality e.g. surface roughness and dimensional accuracy. The
discontinuous droplets and distortions in single track formations, which influence both surface
roughness and dimensional accuracy, were investigated. The physical mechanisms of the
formations of the droplets and distortions were proposed and the heat transfer simulations based
on the Finite Element Method were established to predict the possibility of the droplet formation
and the magnitude of the distortion. Experiments using Electron Beam Melting were then
conducted to validate the physical and numerical models. The good agreements of the simulated
and experimental results demonstrated that the proposed models are simple and efficient to provide
quantitative predictions of the distortions. | null | null | null | null | null | null |
['Bernardo, Jesse', 'Samavedi, Satyavrata', 'Williams, Christopher B.', 'Morgan, Abby W.'] | 2021-10-04T20:01:39Z | 2021-10-04T20:01:39Z | 9/23/10 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/88331', 'http://dx.doi.org/10.26153/tsw/15270'] | eng | 2010 International Solid Freeform Fabrication Symposium | Open | ['tissue scaffold', 'additive manufacturing', 'fused deposition modeling', 'biomimetic mineralization'] | Towards Indirect Tissue Scaffold Fabrication via Additive Manufacturing and Hydroxyapatite Mineralization | Conference paper | https://repositories.lib.utexas.edu//bitstreams/0b23377d-f0de-46c6-91d2-dc29c0488ad4/download | University of Texas at Austin | Unlike traditional stochastic scaffold fabrication techniques, additive manufacturing (AM) can be used to create
tissue-specific three-dimensional scaffolds with controlled porosity and pore geometry. Directly fabricating
scaffolds through AM methods is limited because of the relatively few biocompatible materials available for
processing in AM machines. To alleviate these material limitations, an indirect fabrication method is proposed.
Specifically, the authors investigate the use of Fused Deposition Modeling to fabricate scaffold patterns of varied
pore size and geometry. The scaffold patterns are then mineralized with a biocompatible ceramic (hydroxyapatite).
A heat treatment is then used to pyrolyze the pattern and to sinter the thin ceramic coating. The result is a
biocompatible ceramic scaffold composed of hollow tubes, which may promote attachment of endothelial cells and
vascularization [1].
In this paper, the authors explore the scaffold pattern fabrication and mineralization processes. Two scaffold
pattern materials are tested [acrylonitrile butadiene styrene (ABS) and investment cast wax (ICW)] to determine
which material is the most appropriate for scaffold mineralization and sintering. While the ICW could not be
thoroughly mineralized despite a sodium hydroxide surface treatment, the ABS patterns were successfully
mineralized following an oxygen plasma surface treatment. A 0.004 mm mineral coating was found on the ABS
patterns that featured a strut offset of 0.3 mm, which is in the range of appropriate pore size for bone tissue
engineering [2]. | null | null | null | null | null | null |
['Nettekoven, Alexander', 'Fish, Scott', 'Beaman, Joseph', 'Topcu, Ufuk'] | 2023-02-09T16:04:24Z | 2023-02-09T16:04:24Z | 2022 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/117438', 'http://dx.doi.org/10.26153/tsw/44319'] | eng | 2022 International Solid Freeform Fabrication Symposium | Open | ['LPBF', 'SLS', 'SLM', 'laser track', 'pre-processing', 'efficient storage'] | Towards Online Monitoring and Data-Driven Control: A Study of Segmentation Algorithms for Laser Powder Bed Fusion Processes | Conference paper | https://repositories.lib.utexas.edu//bitstreams/de475f04-6b30-4cb0-a2d8-4f9ea8901b16/download | null | An increasing number of laser powder bed fusion machines use off-axis infrared cameras to improve online moni-
toring and data-driven control capabilities. However, there is still a severe lack of algorithmic solutions to properly
process the infrared images from these cameras, which has led to several key limitations: a lack of online moni-
toring capabilities for the laser tracks, insufficient pre-processing of the infrared images for data-driven methods,
and large memory requirements for storing the infrared images. To address these limitations, we study over 30
segmentation algorithms that segment each infrared image into a foreground and background. By evaluating each
algorithm based on its segmentation accuracy, computational speed, and spatter detection characteristics, we iden-
tify promising algorithmic solutions. The identified algorithms can be readily applied to the laser powder bed
fusion machines to address each of the above limitations and thus, significantly improve process control. | null | null | null | null | null | null |
['Williams, Christopher B.', 'Mistree, Farrokh', 'Rosen, David W.'] | 2020-02-21T14:49:56Z | 2020-02-21T14:49:56Z | 8/26/05 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/80059', 'http://dx.doi.org/10.26153/tsw/7081'] | eng | 2005 International Solid Freeform Fabrication Symposium | Open | ['Additive Manufacturing', 'Cellular Materials'] | Towards the Design of a Layer-Based Additive Manufacturing Process for the Realization of Metal Parts of Designed Mesostructure | Conference paper | https://repositories.lib.utexas.edu//bitstreams/8608f073-4f92-4da0-bf99-d8d088f51b9d/download | null | Low-density cellular materials, metallic bodies with gaseous voids, are a unique class of materials that have
high strength, good energy absorption characteristics, good thermal and acoustic insulation properties, accompanied
by an extremely low mass. Unfortunately, current cellular material manufacturing processes severely limit a
designer’s ability to control the part mesostructure, the material composition, and the part macrostructure.
As such, the authors look towards the use of layer-based additive manufacturing (AM) as a means of providing
the design freedom that is currently absent from cellular material manufacturing processes. Since current metalbased AM techniques do not offer an adequate means of satisfying the unique requirements of cellular materials, the
authors carry out the conceptual design of a new AM process that is dedicated to the manufacture of cellular
materials. Specifically, the authors look to the layer-based additive fabrication of metal oxide powders followed by
post-processing in a reducing atmosphere as a means of fabricating three-dimensional, low-density cellular metal
parts with designed mesostructure. In this paper, the authors detail this conceptual design process and select
working principles that are worthy of further investigation. | null | null | null | null | null | null |
['Smet, M.', 'Li, G.', 'Goossens, L.R.', 'Buls, S.', 'Van Hooreweder, B.'] | 2024-03-27T16:03:51Z | 2024-03-27T16:03:51Z | 2023 | Mechanical Engineering | null | ['https://hdl.handle.net/2152/124499', 'https://doi.org/10.26153/tsw/51107'] | en | 2023 International Solid Freeform Fabrication Symposium | Open | ['laser powder bed fusion', 'lattice production', 'copper', 'additive manufacturing'] | TOWARDS THE LIMITS IN COPPER LATTICE PRODUCTION VIA FIBER LASER POWDER BED FUSION | Conference paper | https://repositories.lib.utexas.edu//bitstreams/d0557fe8-a571-4138-b583-586bef40cea1/download | University of Texas at Austin | Additive manufacturing of copper, by means of Laser Powder Bed Fusion (LPBF), paves the way for
innovation in thermal systems and heat transfer devices. Recent simulations have shown that by interchanging
typical fin designs with more complex structures, an overall improvement in pressure drop and weight can be
obtained while offering the same thermal performance. Here, small-scale lattice structures are especially of
interest for AM as they form a reliable, periodic infill. However, until now, their study has been mainly theoretical.
To analyze these structures in more detail, an in-house built LPBF machine at KU Leuven has been successfully
used to manufacture pure copper parts. Measurements showed a conductivity exceeding 100%IACS, which is the
result of low contamination and low porosity in the as-built material. In this work, the parameter optimization for
thin-walled lattices is discussed, the limitations in terms of minimal feature size are described and physical
mechanisms behind these limitations are uncovered. | null | null | null | null | null | null |