author
stringlengths
4
285
date.accessioned
stringlengths
20
20
date.available
stringlengths
20
20
date.issued
stringclasses
75 values
description.department
stringclasses
3 values
identifier
stringclasses
387 values
identifier.uri
stringlengths
32
78
language.iso
stringclasses
8 values
relation.ispartof
stringclasses
33 values
rights.restriction
stringclasses
2 values
subject
stringlengths
2
254
title
stringlengths
7
239
type
stringclasses
3 values
pdf
stringlengths
93
93
publisher
stringclasses
1 value
abstract
stringlengths
109
3.61k
description.sponsorship
stringclasses
100 values
description
stringclasses
16 values
title.alternative
stringclasses
1 value
contributor.utaustinauthor
stringclasses
1 value
language
stringclasses
1 value
identifier.url
stringclasses
1 value
['Lee, Insup', 'Manthiram, A.', 'Marcus, H.L']
2018-10-03T18:17:05Z
2018-10-03T18:17:05Z
1994
Mechanical Engineering
doi:10.15781/T26970H2C
http://hdl.handle.net/2152/68668
eng
1994 International Solid Freeform Fabrication Symposium
Open
['optimum composite system', 'solid freeform fabrication', 'CAD']
Selective Laser Sintering of Alumina-Boron Oxide Composites
Conference paper
https://repositories.lib.utexas.edu//bitstreams/e9feabc5-da14-4bae-8bbf-4bec8c3176ca/download
null
The selection of an optimum composite system for selective laser sintering (SLS) is based on materials properties such as the melting point and the wettability between the components in the composite powder. The alumina-boron oxide composite system is attractive for SLS because the presence of the low melting component B203 (melting point 4500 C) can enhance sintering. A better wetting of solid alumina powder by molten boron oxide can also aid densification process. The alumina-boron oxide conlposite system has been investigated by SLS and selective laser reactive sintering (SLRS). The role of boron oxide content as a binder, laser power density, and secondary heat treatment on the microstructure and mechanical properties is discussed.
null
null
null
null
null
null
['Lee, Insup', 'Manthiram, A.', 'Marcus, H.L.']
2018-10-03T20:53:54Z
2018-10-03T20:53:54Z
1995
Mechanical Engineering
doi:10.15781/T2GM82732
http://hdl.handle.net/2152/68689
eng
1995 International Solid Freeform Fabrication Symposium
Open
['SLS', 'alumina', 'x-ray diffraction']
Selective Laser Sintering of Alumina-Zinc Borosilicate Glass Composites using Monoclinic HB02 as a Binder
Conference paper
https://repositories.lib.utexas.edu//bitstreams/e61f83db-2f43-41a3-ae15-303451ba7297/download
null
Selective Laser Sintering (SLS) process has been employed to fabricate alumina-glass composites using as an inorganic binder monoclinic HB02. Subsequent post-thermal processing of green SLS parts at various temperatures yielded glass-ceramic composites. The crystalline phases and microstructural evolution at each fIring temperature were identified by X-ray diffraction analysis and Scanning Electron Microscopy. The role of glass content, firing temperature, and alumina particle size on the densification and bend strength of fired samples were studied. In addition, further densification was made through infiltration of colloidal silica into the fIred, porous samples.
null
null
null
null
null
null
['Manriquez-Frayre, J.A.', 'Bourell, D.L.']
2018-04-10T18:38:39Z
2018-04-10T18:38:39Z
1990
Mechanical Engineering
doi:10.15781/T2B27Q79P
http://hdl.handle.net/2152/64245
eng
1990 International Solid Freeform Fabrication Symposium
Open
['Center for Materials Science and Engineering', 'laser processing', 'energy dispersive spectroscopy']
Selective Laser Sintering of Binary Metallic Powder
Conference paper
https://repositories.lib.utexas.edu//bitstreams/a94e6660-f638-4fb0-91a9-6fd5375a0d29/download
null
A selective laser sintering technique has been used to process metal powders and powder blends. Precursor powders include copper, tin, a 70Pb-30Sn solder and their blends. Excessive balling due to surface free energy effects occurred in single layer tests when the laser fluence was sufficient to cause melting of monolithic tin or solder. Improvements in single layer quality were obtained using copper-solder powder blends in a reducing atmosphere. The binary powder layers were characterized metallographically and the effect of processing parameters such as laser fluence and scan speed were assessed. Post-process annealing improved interparticle wetting and part strength. The influence of ZnCl2 flux was investigated when present as a coating in copper-solder blends. Multiple layer tests were performed on the most promising powder blends and the results are presented.
null
null
null
null
null
null
['Lorrison, J.C.', 'Goodridge, R.D.', 'Daigarno, K.W.', 'Wood, D.J.']
2019-10-22T17:23:44Z
2019-10-22T17:23:44Z
2002
Mechanical Engineering
null
['https://hdl.handle.net/2152/76320', 'http://dx.doi.org/10.26153/tsw/3409']
eng
2002 International Solid Freeform Fabrication Symposium
Open
Sintering
Selective Laser Sintering of Bioactive Glass-Ceramics
Conference paper
https://repositories.lib.utexas.edu//bitstreams/f706ae15-7e4e-4dbc-8305-31662761440a/download
null
An initial investigation was held into the feasibility of producing bone replacement implants from a bioactive glass-ceramic using the Selective Laser Sintering (SLS) process. The work presented considers both a direct and an indirect approach, where the material is sintered with a polymer binder and subsequently post-processed. An existing material with potentially suitable biological and mechanical properties was selected from the range of apatite-mullite glass-ceramics in the SiO2-Al2O3-CaO-CaF2-P2O5 series. The viability of using this material with the SLS process was then tested, and the process route and resulting material properties characterised. It is concluded that both direct and indirect SLS processes have potential in the manufacture of personalised bone replacement applications.
null
null
null
null
null
null
['Lee, Goonhee', 'Barlow, J.W.']
2018-05-03T20:05:32Z
2018-05-03T20:05:32Z
1993
Mechanical Engineering
doi:10.15781/T26Q1T10X
http://hdl.handle.net/2152/65082
eng
1993 International Solid Freeform Fabrication Symposium
Open
['Selective Laser Sintering', 'SLS', 'Department of Chemical Engineering']
Selective Laser Sintering of Bioceramic Materials for Implants
Conference paper
https://repositories.lib.utexas.edu//bitstreams/a7d9750a-4121-4be2-9f91-2b5643c5ca6a/download
null
Selective Laser Sintering (SLS) process is employed for fabrication of biocerarnics for orthopedic implants. Hydroxyapatite and Calcium Phosphate ceramics are coated with polymer as a intermediate binder by using a spray drier. Polymer coated materials are SLS processed to make green parts, which are infiltrated and fired to remove the polymer. SLS processed green parts of hydroxyapatite have low density due to the small particle size with large specific surface area. This paper discusses the possibilities and problems in free-form fabrication of bioceramic.
null
null
null
null
null
null
['Lee, Gonhee', 'Barlow, J.W.']
2018-10-03T15:29:00Z
2018-10-03T15:29:00Z
1994
Mechanical Engineering
doi:10.15781/T25D8P040
http://hdl.handle.net/2152/68645
eng
1994 International Solid Freeform Fabrication Symposium
Open
['selective laser sintering', 'Polymeric Binder', 'Powder X-ray diffraction']
Selective Laser Sintering of Calcium Phosphate Powders
Conference paper
https://repositories.lib.utexas.edu//bitstreams/47677941-00c0-4206-b379-bc9fe3079ea6/download
null
Since Dejong first observed the similarity between powder X - ray diffraction pattern ofthe in vivo mineral and the hydroxyapatite (Cas(OH)(P04h ,HA) in 1926, the calcium phosphate ceramics have received attention as a bone substitute material. Five calcium phosphates which exhibit different X-ray diffraction patterns are known to be precipitated from aqueous solution at normal pressure. [1] These are Ca(HzP04h, Ca(HzP04h-H20, CaHP04 , CaHP04-2H20, and crystalline precipitate of variable composition of hydroxyapatite with the base formula Cas(OH)(P04h. Various forms of calcium phosphate compounds, Ca/P ratio range from 0.5 to 1, are prepared from HA by reacting with phosphoric acid. Thermally dehydrated calcium phosphates are known to form a CaO and P20 S binary system. It is known that for the CaO and P20S binary system, the chain phosphates appear between the orthophosphate (mole ratio ofCaO/P20 S =3) and metaphosphate (mole ratio ofCaO/P20s =1) and ultraphosphate for which mole ratio ofCaO/P20 s iess than 1. Particularly in the case ofmetaphosphate, very high degree of polymerization and as a consequence, good mechanical properties are reported. In this binary system, mole ratio ofCaO/P20 S less than 55145 forms a glass-like structure from the melt, and its mechanical properties are known to be nearly same as those of natural teeth.[2]
null
null
null
null
null
null
['Lakshminarayan, Uday', 'Ogrydiziak, Stan', 'Marcus, H.L.']
2018-04-10T16:30:03Z
2018-04-10T16:30:03Z
1990
Mechanical Engineering
doi:10.15781/T2MG7GC58
http://hdl.handle.net/2152/64235
eng
1990 International Solid Freeform Fabrication Symposium
Open
['Center for Materials Science and Engineering', 'Department of Mechanical Engineering', 'Selective Layer Sintering', 'SLS']
Selective Laser Sintering of Ceramic Materials
Conference paper
https://repositories.lib.utexas.edu//bitstreams/ce95e944-890f-46ac-a6e4-59de3505f3fa/download
null
This paper will focus on efforts to develop the alumina - ammonium phosphate material system for Solid Freeform Fabrication. When the powder mix is irradiated with a laser beam, ammonium phosphate ( m.p. """ 190 0 C ) melts and forms a glassy phase between the alumina grains. The "green part" obtained by laser processing is then subjected to secondary heat treatment to optimize the properties of the final composite. The effect of various material, laser and machine parameters on the density, strength, surface finish and microstructure of the final part are described. One of the applications for selective laser sintering is its use in directly manufacturing ceramic molds for the investment casting process. We will describe some of the the results we have obtained so far in fabricating composite ceramic molds directly and using them to cast metals.
null
null
null
null
null
null
['Frayre-Manriquez, J.A.', 'Bourell, D.L.']
2018-04-17T18:21:12Z
2018-04-17T18:21:12Z
1991
Mechanical Engineering
doi:10.15781/T2CF9JQ1W
http://hdl.handle.net/2152/64343
eng
1991 International Solid Freeform Fabrication Symposium
Open
['Center for Materials Science and Engineering', 'SLS', 'Selective Layer Sintering', 'Polymer']
Selective Laser Sintering of Cu-Pb/Sn Solder Powders
Conference paper
https://repositories.lib.utexas.edu//bitstreams/e081bb9d-b0a9-45d5-bf97-1687967d1e97/download
null
Solid Freeform Fabrication (SFF) as an overall approach in the manufacturing field has been applied to very different areas and on different materials systems including polymers, ceramics, metals and vapor phase. Even though it is clear that polymers have enjoyed a rapid and successful advance in terms of applications, research in the other areas have shown potential applications as well. In this paper, Cu-Sn/Pb solder and Cu-Sn blends have been used as starting material for the Selective Laser Sintering (SLS) manufacture of SFF objects. The general properties of the objects thus produced are presented. In particular, density and microstructural characterizations results are discussed..
null
null
null
null
null
null
['Neff, Clayton', 'Hopkinson, Neil', 'Crane, Nathan B.']
2021-10-21T16:57:33Z
2021-10-21T16:57:33Z
2015
Mechanical Engineering
null
https://hdl.handle.net/2152/89405
eng
2015 International Solid Freeform Fabrication Symposium
Open
['diamond lattice structures', 'selective laser sintering', 'elastic modulus']
Selective Laser Sintering of Diamond Lattice Structures: Experimental Results and FEA Model Comparison
Conference paper
https://repositories.lib.utexas.edu//bitstreams/c6234856-921d-4c72-8923-3a20fab99170/download
University of Texas at Austin
Nature utilizes multiple materials with varying properties to create high performance, integrated systems. In contrast, most additive manufacturing processes are limited to a small set of compatible materials to fabricate a device. However, the large geometric freedom of AM could be used to create the effect of multiple properties by creating lattice structures. Prior work has focused on using this concept to reduce weight in high stiffness structures. This paper will consider the use of a diamond lattice structures to create the effect of materials with a low elastic modulus materials. Low stiffness regions are advantageous for energy absorption, vibration isolation, and reduction of stress due to dimensional or temperature mismatches. The diamond lattice possesses Face-Centered-Cubic (FCC) elemental configuration possessing tetrahedral angles of 109° between elements. This allows for a pliable moment exerted on the structure yielding a flexible and energy absorbent arrangement. A range of devices was fabricated in Nylon 12 (PA 2200) through Laser Sintering (LS) process with variable element size (thickness) and unit cell size. The effective stiffness of the structures is compared as a function of these parameters and compared to numerical simulation. The results show the possibility of tuning the effective elastic modulus by over four orders of magnitude.
null
null
null
null
null
null
['Sriram, Vinay', 'Wood, Kristin', 'Bourell, David', 'Beaman, Joseph J.']
2019-11-21T18:37:37Z
2019-11-21T18:37:37Z
2003
Mechanical Engineering
null
['https://hdl.handle.net/2152/78563', 'http://dx.doi.org/10.26153/tsw/5619']
eng
2003 International Solid Freeform Fabrication Symposium
Open
DuraForm
Selective Laser Sintering of DuraForm Polyamide with Small-Scale Features
Conference paper
https://repositories.lib.utexas.edu//bitstreams/ceb2ceaa-0985-4e90-96e3-5bab44d5b19f/download
null
Selective Laser Sintering (SLS) has been used to make a fiber management module having very small feature size and ratios. Currently these modules are made out of Stereolithography using standard epoxy acrylate materials. SLS has been chosen to make these modules by the virtue of the material system it offers. The material system was chosen based on the flame retardant properties. The material used for this study is a DuraformTM Polyamide and Alumina-Ammonium Phosphate system. Ammonium Phosphate served as the binder in the Alumina-Ammonium Phosphate system. Experiments were done in order to find out the minimum feature size possible with the two material systems. Minimum hole diameters and maximum possible l/d ratios are determined by particle size, shape and processing conditions. Builds were made in different directions to understand the effect of the various processing parameters on the system. One particularly noteworthy observation was that part growth as a proportion of hole diameter became increasingly significant as hole size decreased. Optical microscopy was performed to measure the hole diameters and also to reveal the surface roughness. Results indicate material system determines the minimum diameter of micro-sized holes that can be effectively manufactured using Selective Laser Sintering.
null
null
null
null
null
null
['Das, S.', 'Harlan, N.', 'Beaman, J. J.', 'Bourell, D. L.']
2018-11-09T15:21:58Z
2018-11-09T15:21:58Z
1996
Mechanical Engineering
doi:10.15781/T2Q815C0Q
http://hdl.handle.net/2152/69925
eng
1996 International Solid Freeform Fabrication Symposium
Open
['HIP', 'SLS', 'encapsulate powder']
Selective Laser Sintering of High Performance High Temperature Materials
Conference paper
https://repositories.lib.utexas.edu//bitstreams/4a8d1699-d194-4681-8be0-fb0de494fca3/download
null
Hot Isostatic Pressing (HIP) of high performance metal parts is currently done using either a shaped metal container or a pre-fabricated ceramic mold depending on the part material and geometry. An alternative method of HIP encapsulation that allows complex part geometry, short cycle time and minima) potential for container-powder bed interaction is desired. Integral, fully dense metal skins with complex geometry can potentially be constructed by direct selective laser sintering (SLS). The advantages ofin-situ HIP encapsulation by direct SLS include the elimination of a secondary container material and any associated container-powder bed interaction, reduced pre-processing time and a short HIP cycle. Single and multi-layer specimens of Inconel625, Ti-6AI-4Vand 17-4 PH stainless steel were produced by direct SLS. Closed porosity in Inconel625 and 17-4 PH stainless steel samples ranged from 0 to 12% and area porosity from 0.5 to 20%, depending on the laser energy density. Direct SLS samples ofInconel 625 were subjected to helium leak testing and found to be impervious, with a leak rate less than lxl0-10 atm eels. These samples met the criteria for containerless hot isostatic pressing.
null
null
null
null
null
null
['Hostetler, John M.', 'Goldstein, Jonathan T.', 'Urbas, Augustine M.', 'Gutierrez, Rodrigo E.', 'Bender, Theresa E.', 'Wojnar, Charles S.', 'Kinzel, Edward C.']
2021-10-28T14:24:59Z
2021-10-28T14:24:59Z
2016
Mechanical Engineering
null
https://hdl.handle.net/2152/89648
eng
2016 International Solid Freeform Fabrication Symposium
Open
['silica parts', 'thermal expansion', 'low density', 'low coefficient', 'selective laser sintering']
Selective Laser Sintering of Low Density, Low Coefficient of Thermal Expansion Silica Parts
Conference paper
https://repositories.lib.utexas.edu//bitstreams/b33959fa-e3b4-4b55-ad02-3df8c5094c56/download
University of Texas at Austin
This paper presents a study of selective laser sintering of silica-gel. The objective of this work is to investigate a technique to create free-form, low to zero coefficient of thermal expansion structures. This offers potential cost savings over the conventional casting of large pieces of glass-ceramic followed by machining lightening features. In this paper, A CO2 laser is coupled through a gantry system and focused onto a binder-free silica-gel powder bed (15-40 µm particles). Prior to writing each layer, powder is dispensed by sifting it onto the build platform as opposed to a conventional wiper system. This avoids contacting and potentially damaging sensitive parts. After deposition, the parts are annealed in a furnace to increase their strength. The influence of various process parameters including scan speed and laser power on final shape is investigated. In addition, the flexural strength of annealed parts is measured via three-point bending tests.
null
null
null
null
null
null
['Hejmadi, Uday', 'McAlea, Kevin']
2018-11-09T15:35:21Z
2018-11-09T15:35:21Z
1996
Mechanical Engineering
doi:10.15781/T2KH0FJ5G
http://hdl.handle.net/2152/69926
eng
1996 International Solid Freeform Fabrication Symposium
Open
['SLS process', 'CAD', 'RapidTool process']
Selective Laser Sintering of Metal Molds: The Rapidtool Process
Conference paper
https://repositories.lib.utexas.edu//bitstreams/b60c6f61-b5b1-4d20-bf9e-e95b8c03ccba/download
null
Complex three dimensional parts can be manufactured directly from CAD data using rapid prototyping processes. SLS® Selective Laser Sintering is a rapid prototyping process developed at the University ofTexas at Austin and commercialized by DTM Corporation. SLS parts are constructed layer by layer from powdered materials using laser energy to melt CAD specified cross sections. Polymer, metal, and ceramic powders are all potential candidate materials for this process. In this paper, a commercial SLS process - the RapidTool Process - which allows metal molds to be rapidly manufactured is described. With this process, a polymer coated carbon steel powder is used to fabricate a "green part" in the SLS machine. The green part is then placed in a furnace with blocks of copper and, in a single furnace cycle, the polymer coating is removed and the steel skeleton is infiltrated with the copper. The resulting steel/coPPer composite material has durability and thermal conductivity similar to aluminum and can be hand finished using standard techniques. A finished mold core and cavity set which can be used to mold at least 50,000 parts with most plastics can be prepared in approximately ten days. The cost to produce most mold geometries with the RapidTool Process is also comPetitive with traditional mold-making methods.
null
null
null
null
null
null
['Klatt, Timothy', 'Haberman, Michael', 'Conner Seepersad, Carolyn']
2021-10-12T18:56:05Z
2021-10-12T18:56:05Z
2013
Mechanical Engineering
null
['https://hdl.handle.net/2152/88719', 'http://dx.doi.org/10.26153/tsw/15653']
eng
2013 International Solid Freeform Fabrication Symposium
Open
['bistable structures', 'mesostructures', 'honeycombs', 'selective laser sintering']
Selective Laser Sintering of Negative Stiffness Mesostructures for Recoverable, Nearly-Ideal Shock Isolation
Conference paper
https://repositories.lib.utexas.edu//bitstreams/e0f51767-358c-447a-94bb-06774051a85a/download
University of Texas at Austin
Honeycomb materials are well known for providing lightweight stiffness, strength, and energy absorption capabilities. For most honeycomb materials, energy absorption occurs when individual cells collapse progressively. Although it is possible for honeycombs with very low relative density to collapse via elastic buckling, honeycombs with typical relative densities collapse due to plastic yielding and buckling of the cell walls, such that the energy absorption is nonrecoverable. In this paper, mono-stable negative stiffness unit cells are investigated for constructing honeycomb mesostructures with high levels of recoverable energy absorption. Negative stiffness is achieved by incorporating curved beams into each unit cell. When subject to transverse loading, the curved beams exhibit negative stiffness behavior as they transition from one curved geometry to another in a snap-through type of motion that absorbs energy elastically at a relatively constant plateau stress. The plateau stress at which this energy absorption occurs can be tailored via the geometry of the unit cell. Preliminary experiments indicate that the structures can absorb significant amounts of energy by requiring nearly-constant-force to increase deformation as the structure transitions between snap-through configurations. Unlike traditional honeycombs, the negative stiffness mesostructures are self-resettable and therefore reusable. Using SLS as a means of fabrication, they can also be customized for specific shock events and even functionally graded to offer shock isolation for transient loads of various amplitudes.
null
null
null
null
null
null
['Schultz, Jeffrey P.', 'Martin, Julie P.', 'Kander, Ronald G.', 'Suchicital, Carlos T.A.']
2019-09-20T18:28:35Z
2019-09-20T18:28:35Z
2000
Mechanical Engineering
null
['https://hdl.handle.net/2152/75927', 'http://dx.doi.org/10.26153/tsw/3026']
eng
2000 International Solid Freeform Fabrication Symposium
Open
Alloying
Selective Laser Sintering of Nylon 12-PEEK Blends Formed by Cryogenic Mechanical Alloying
Conference paper
https://repositories.lib.utexas.edu//bitstreams/532d12ec-ee5d-4f45-aedb-f14b358246cc/download
null
Cryogenic mechanical alloying (CMA) has been shown to be an effective means for producing composite powders with co-continuous phases throughout each particle. Consolidation of these composite particles via SLS presents the possibility of forming parts with a co-continuous microstructure. In this work the effects of milling time and PEEK volume fraction on the microstructure and mechanical properties of laser sintered Nylon 12-PEEK blends is studied. In both blends, the PEEK phase is incorporated to increase mechanical strength, stiffness and heat deflection temperature. Transmission electron microscopy and scanning electron microscopy is utilized to investigate the microstructure of the CMA powder and laser sintered parts.
null
null
null
null
null
null
['Faustini, Mario C.', 'Neptune, Richard R.', 'Crawford, Richard H.', 'Stanhope, Steven J.']
2020-02-27T20:36:29Z
2020-02-27T20:36:29Z
2006
Mechanical Engineering
null
['https://hdl.handle.net/2152/80102', 'http://dx.doi.org/10.26153/tsw/7123']
eng
2006 International Solid Freeform Fabrication Symposium
Open
Passive dynamic ankle-foot orthoses
Selective Laser Sintering of Passive Dynamic Ankle-Foot Orthoses
Conference paper
https://repositories.lib.utexas.edu//bitstreams/f17d54af-5b69-41fc-a227-514c3855aa69/download
null
Passive dynamic ankle-foot orthoses (AFO’s) are used to improve gait performance in those with various neuromuscular disorders. An important design characteristic of passive dynamic AFOs is the storage and release of elastic energy within its structure to help satisfy the energetic demands of walking. Thus, minimizing energy dissipation through internal friction is a fundamental criterion for selecting the appropriate AFO material. This study compared the mechanical damping of a carbon-fiber AFO to three geometrically identical AFO’s fabricated using selective laser sintering with different materials. Mechanical damping characteristics ranked the materials as Nylon 11 (best), followed by DuraformTM PA and DuraformTM GF (worst).
null
null
null
null
null
null
['Childs, T.H.C.', 'Cardie, S.', 'Brown, J.M.']
2018-10-03T18:22:47Z
2018-10-03T18:22:47Z
1994
Mechanical Engineering
doi:10.15781/T2XS5K244
http://hdl.handle.net/2152/68670
eng
1994 International Solid Freeform Fabrication Symposium
Open
['sintering of polycarbonate', 'selective laser sintering', 'temperature distribution']
Selective Laser Sintering of Polycarbonate at Varying Powers, Scan Speeds and Scan Spacings
Conference paper
https://repositories.lib.utexas.edu//bitstreams/3487242d-8b34-41a1-8b34-24a12d726ee2/download
null
A benchmark study (1) has shown selective laser sintering to be the equal of or to have accuracy advantages over other processes for creating parts of size over 10 mm. Experience is needed to achieve best accuracies, as with other processes. This paper is (for us) a first step in understanding the relation between sintering parameters, part size and acuracy. Work at the University of Texas at Austin (2-4) has established that the sintering of polycarbonate can be understood in terms of a rate model driven by viscous and surface tension effects. Material properties are such that a sharp boundary exists between sintered and unsintered material. When full density is not achieved in a part, density within a single layer varies from fully sintered to totally unsintered; measured part density is thus a mean of widely varying values. Published work (3-4) uses a onedimensional non-steady state heat flow model to calculate the temperature profile and densification beneath the surface and concentrates on the effects on this of material properties varying with temperature and during sintering. In this paper, these variations are ignored but a three dimensional non-steady heat flow is used to enable edge effects to be estimated. Density gradients at edges are assumed to be responsible for variations of accuracy with sintering parameters, part size, part shape and orientation.
null
null
null
null
null
null
['Wahab, M. S.', 'Dalgarno, K. W.', 'Cochrane, R. F.']
2020-03-09T15:30:48Z
2020-03-09T15:30:48Z
8/21/07
Mechanical Engineering
null
['https://hdl.handle.net/2152/80200', 'http://dx.doi.org/10.26153/tsw/7219']
eng
2007 International Solid Freeform Fabrication Symposium
Open
polymer nanocomposite
Selective Laser Sintering of Polymer Nanocomposites
Conference paper
https://repositories.lib.utexas.edu//bitstreams/bde27445-6d43-477b-bf37-f9abb136fe67/download
null
This paper describes the fabrication and characterization of polymer nanocomposite (PNC) materials for use in the selective laser sintering (SLS) process. PNC materials are of great interest generally because of their excellent physical properties, and offer excellent potential in rapid manufacturing of structural polymeric parts. Three different nano additive materials have been used: cerium oxide IV, yttrium stabilized zirconia, and layered Hectorite clay. These materials have been used to reinforce PA6 polymer using solution blending and spray drying to create powder with particle sizes in the range of 5-40 µm. The mechanical properties and microstructure of the PNC materials have been evaluated and the results compared to those of unfilled polymer.
null
null
null
null
null
null
['Wang, Hongyun', 'Bourell, David L', 'Beaman Jr., Joseph J.']
2018-12-05T20:37:14Z
2018-12-05T20:37:14Z
1997
Mechanical Engineering
doi:10.15781/T2VT1H935
http://hdl.handle.net/2152/71416
eng
1997 International Solid Freeform Fabrication Symposium
Open
['SLS', 'CAD']
Selective Laser Sintering of Quartz Powder
Conference paper
https://repositories.lib.utexas.edu//bitstreams/db73e8e5-1412-4756-9cf6-fd9ae13bdd6f/download
null
This research describes the feasibility of fusing quartz powder by Selective Laser Sintering (SLS). SLS is a method of rapid prototyping three-dimensional objects from a computer-aided design database. The effects of different processing parameters, including powder size, laser power and scan mte were explored. Single and multiple layer specimens have been made. The resulting structures were evaluated using SEM and the density of the multiple-layer structure was detected by a geometrical mass/volume technique. It was determined that particle size was the dominant variable affecting part quality. Smaller and spherical unifonn particles are preferred. Future work will concentrate on optimizing powder size and shape and higher laser power.
null
null
null
null
null
null
['Gill, Toby', 'Hon, Bernard']
2019-10-25T16:05:05Z
2019-10-25T16:05:05Z
2002
Mechanical Engineering
null
['https://hdl.handle.net/2152/77441', 'http://dx.doi.org/10.26153/tsw/4530']
eng
2002 International Solid Freeform Fabrication Symposium
Open
Laser Sintering
Selective Laser Sintering of SiC/Polyamide Matrix Composites
Conference paper
https://repositories.lib.utexas.edu//bitstreams/9db2ff3f-bcf2-425b-8171-b443ffe46305/download
null
This paper presents an experimental study into the production of particulate Silicon Carbide/Duraform Polyamide matrix composites via the selective laser sintering (SLS) process. FEPA standard SiC grits, F240 and F360, were each individually blended with the commercially available Duraform Polyamide, to produce blend compositions of 50 and 60 volume percent SiC for direct SLS processing. A full factorial experimental approach was applied to examine the effects and interactions of laser power, scan speed, scan spacing and layer thickness, with regards to the mechanical and physical properties of sintered parts. Analysis of parameter interactions and individual main effects as well as Pareto analysis for all parameter combinations are presented for the responses of part porosity and strength.
The authors would like to acknowledge the financial support from the EPSRC and the technical support and assistance of the PIDC.
null
null
null
null
null
['Hauser, C.', 'Childs, T.H.C.', 'Dalgamo, K.W.']
2019-03-12T17:55:45Z
2019-03-12T17:55:45Z
1999
Mechanical Engineering
null
['https://hdl.handle.net/2152/73606', 'http://dx.doi.org/10.26153/tsw/748']
eng
1999 International Solid Freeform Fabrication Symposium
Open
['Rapid prototyping', 'Selective laser sintering']
Selective Laser Sintering of Stainless Steel 314S HC Processed Using Room Temperature Powder Beds
Conference paper
https://repositories.lib.utexas.edu//bitstreams/d5b54c32-7bb3-4eed-b890-8e7b570e27d7/download
null
Metal powder bed pre-heating is a proposed route for the homogenisation of temperature gradients that can otherwise cause individual layer warping and cracking in direct metal Selective Laser Sintering (SLS). However, the high temperatures involved complicate a relatively simple process. This paper reports on the conditions for successful small scale SLS of binderless stainless steel 314S powders within the surrounds of a room temperature powder bed. Results show that a scan length around 15.0mm and a scan spacing around 0.275mm produce sintered layers showing no signs of warping. Experimentation also indicates that single layer shape. effects warping but length oflayer propagation does not.
null
null
null
null
null
null
['Harlan, Nicole', 'Park, Seok-Min', 'Bourell, David L.', 'Beaman, Joseph J.']
2019-03-12T20:46:42Z
2019-03-12T20:46:42Z
1999
Mechanical Engineering
null
['https://hdl.handle.net/2152/73609', 'http://dx.doi.org/10.26153/tsw/751']
eng
1999 International Solid Freeform Fabrication Symposium
Open
['SLS', 'tetragonal']
Selective Laser Sintering of Zirconia with Micro-Scale Features
Conference paper
https://repositories.lib.utexas.edu//bitstreams/a2b10c56-09f5-413e-a26a-5311a95ce2a4/download
null
Recent work in Selective Laser Sintering of ceramics at the University of Texas at Austin demonstrates the capability to produce zirconia parts with fine features. Zirconia powder was pre-processed into spherical particles, laser sintered with a sacrificial polymer binder, infiltrated and post-sintered to higher density. Optical micrographs show that hole sizes of 180 /-tm are possible in fully ceramic components.
null
null
null
null
null
null
['Klocke, F.', 'Wirtz, H.']
2019-02-26T20:58:40Z
2019-02-26T20:58:40Z
1998
Mechanical Engineering
null
['https://hdl.handle.net/2152/73502', 'http://dx.doi.org/10.26153/tsw/652']
eng
1998 International Solid Freeform Fabrication Symposium
Open
['Investment Casting', 'Selective Laser Sintering']
Selective Laser Sintering of Zirconium Silicate
Conference paper
https://repositories.lib.utexas.edu//bitstreams/fb7dc01e-5ce3-467e-bb5d-9c9bb074ffde/download
null
The Fraunhofer Institute of Production Technology (IPT) and the Fraunhofer Institute of Laser Technology (ILT) have joined forces in a project dedicated to Selective Laser Sintering (SLS) ofmetals and ceramics, funded by the German Government and 6 industrial partners. Selective Laser Sintering of zirconium silicate as a ceramic material used for investment casting shells and cores is an attractive alternative to the conventional, time-consuming way of producing these shells from a wax master. This paper will present current process results concerning laser sintering of shells made from zirconium silicate and explain the related potentials and benefits.
null
null
null
null
null
null
['Williams, John', 'Miller, David', 'Deckard, Carl']
2018-11-16T15:47:32Z
2018-11-16T15:47:32Z
1996
Mechanical Engineering
doi:10.15781/T2T43JN9H
http://hdl.handle.net/2152/70290
eng
1996 International Solid Freeform Fabrication Symposium
Open
['selective laser sintering', 'radiation', 'thermal gradients']
Selective Laser Sintering Part Strength as a Function of Andrew Number, Scan Rate and Spot Size
Conference paper
https://repositories.lib.utexas.edu//bitstreams/9a2f3611-67e0-42c7-bbb3-f869af44f4d4/download
null
Selective Laser Sintering has been modeled analytically and numerically, and studied experimentally. Further investigation is necessary to couple the results of modeling with experimental data. At Clemson University, numerical modeling of heat transfer phenomena is used to predict temperatures within the powder layer as a function of process parameters. Efforts are focused on delivering process speed up through improved process understanding. Initial modeling results and current understanding of the effects of process parameters on the strength properties offreeform parts produced by the SLS process are presented.
null
null
null
null
null
null
['Cottle, Rand D.', 'Birmingham, Britton', 'Eliezer, Zwy', 'Marcus, Harris L.']
2018-11-08T15:07:43Z
2018-11-08T15:07:43Z
1995
Mechanical Engineering
doi:10.15781/T2GT5G157
http://hdl.handle.net/2152/69883
eng
1995 International Solid Freeform Fabrication Symposium
Open
['SLS', 'nanostructuring', 'powder reprocessing']
Selective Laser Sintering Preparation and Tribological Testing of Nanostructured Tungsten Carbide-Cobalt Composites
Conference paper
https://repositories.lib.utexas.edu//bitstreams/b1c494f2-22bb-4555-b9e8-2880799a67c8/download
null
This paper describes the results to date ofresearch done to compare and contrast the tribological properties ofnanostructured tungsten carbide-cobalt composites consolidated by selective laser sintering (SLS) and conventional grain size composites ofthe same chemical composition consolidated by conventional commercial methods. The powder preprocessing and selective laser sintering methods will briefly be described. The tribological testing methods will be discussed, and the tribological properties ofthe selective laser sintered and commercially consolidated materials will be compared. It will be seen that the nanosized WC-Co composites have far superior harness and wear resistance compared to their microsized counterparts.
null
null
null
null
null
null
['Shi, Dongping', 'Gibson, Ian']
2019-03-11T16:31:43Z
2019-03-11T16:31:43Z
1999
Mechanical Engineering
null
['https://hdl.handle.net/2152/73579', 'http://dx.doi.org/10.26153/tsw/721']
eng
1999 International Solid Freeform Fabrication Symposium
Open
['Rapid Prototyping', 'Selective Laser Sintering']
Selective Laser Sintering Process Management Using a Relational Database
Conference paper
https://repositories.lib.utexas.edu//bitstreams/915a2f6d-dca5-4334-8ccb-fb794ee842c5/download
null
With more and more materials used in the Selective Laser Sintering (SLS) process, it is becoming necessary to use a database to manage the process efficiently. In this paper, a relational database for the SLS process is described. The database includes powdered material data, sintering parameters, machine characteristics, mechanical properties and surface quality of prototypes. Use ofthis database will make it is easy to store and retrieve processing information and make decisions for planning the SLS. This paper will go on to describe how the database can be extended to include other RP technologies.
null
null
null
null
null
null
['Weiss, Wendy', 'Bourell, D.L.']
2018-04-17T18:40:33Z
2018-04-17T18:40:33Z
1991
Mechanical Engineering
doi:10.15781/T2G737M79
http://hdl.handle.net/2152/64350
eng
1991 International Solid Freeform Fabrication Symposium
Open
['Center for Materials Science and Engineering', 'intermetallic', 'metallographic techniques', 'x-ray powder']
Selective Laser Sintering to Produce NI-SN Intermetallics
Conference paper
https://repositories.lib.utexas.edu//bitstreams/ef4f9387-f6cf-4f92-98b2-0ff04e053922/download
null
A model system has been employed to investigate .the use of selective laser sintering (SLS) with a post-processing step to produce a compound having different properties than the precursor powders. The powder mixture examined consisted of95% (59% Ni and 41%8n) plus 5% ZnC12. This weight fraction of nickel and. tin produces. the intermetallic compound Ni3Sn upon equilibrium annealing. ZnCl2 was used as a wetting agent. Parts were fabricated using SLS and were then post-process annealed to create the intermetallic. Metallographic techniques and x-ray powder diffraction were used.to characterize the parts before and after annealing.
null
null
null
null
null
null
['Khoshnevis, Behrokh', 'Gao, Xiang', 'Barbara, Brittany', 'Nouri, Hadis']
2021-11-04T15:30:09Z
2021-11-04T15:30:09Z
2017
Mechanical Engineering
null
['https://hdl.handle.net/2152/89986', 'http://dx.doi.org/10.26153/tsw/16907']
eng
2017 International Solid Freeform Fabrication Symposium
Open
['selective separation shaping', 'additive manufacturing', 'cementitious', 'composite']
Selective Separation Shaping (SSS) – Large-Scale Fabrication Potentials
Conference paper
https://repositories.lib.utexas.edu//bitstreams/a2cfbfca-d7f5-4ef0-ae4a-1fe5fc7f21dc/download
University of Texas at Austin
Selective Separating Shaping is a new additive manufacturing technique which is capable of processing polymeric, metallic, ceramic and composites including cementitious materials. In earlier experiments the capabilities of SSS in making metallic and ceramic parts have been demonstrated. The focus of the research reported in this paper has been on exploration of capabilities of SSS for creation of large-scale cementitious composite parts. A prototype machine has been used to create specimens made of regular construction cement (lime based), Sorel cement (magnesia based) and gypsum based composites. The fabrication results, surface quality and flexural strength for these experiments are presented.
null
null
null
null
null
null
['Nouri, H.', 'Khoshnevis, B.']
2021-11-04T15:26:46Z
2021-11-04T15:26:46Z
2017
Mechanical Engineering
null
['https://hdl.handle.net/2152/89985', 'http://dx.doi.org/10.26153/tsw/16906']
eng
2017 International Solid Freeform Fabrication Symposium
Open
['selective separation shaping', 'polymeric parts', 'nylon', '3D printing']
Selective Separation Shaping of Polymeric Parts
Conference paper
https://repositories.lib.utexas.edu//bitstreams/6d5728ab-b926-4b27-b3c4-aff124eede74/download
University of Texas at Austin
Additive manufacturing (AM), or 3D printing has enjoyed a recent surge of attention over the past decade. AM is a process in which digital 3D design data is used as input to build physical objects by combining sequence layers of material. By increasing demand in use of additive manufacturing for fabrication of end-user parts, there is considerable interest in developing new techniques which can offer high quality customized parts at low cost. Selective Separation Shaping (SSS) is a new AM technology developed with the goal of fabricating low cost, high resolution 3D parts. The main advantage of SSS is that this process enables building fully functional pieces without the need of any intermediate binder or high cost laser operation. This process has been primarily applied to metallic, and ceramic materials and test cases were successfully built. There has been no study on fabrication of parts using polymeric material and the goal of this research is to examine successful fabrication of polymer parts. Nylon 6,6 has been used as starting base material and several test cases were fabricated to identify key factors in success of this process. Different classes of nylon are studied to achieve better understanding of material properties on success of fabrication and achieve an effective binding between layers. Finally, 3D printed parts built by SSS are presented.
null
null
null
null
null
null
['Zhang, Jing', 'Khoshnevis, Behrokh']
2021-10-19T17:52:08Z
2021-10-19T17:52:08Z
2015
Mechanical Engineering
null
https://hdl.handle.net/2152/89309
eng
2014 International Solid Freeform Fabrication Symposium
Open
['Selective Separation Sintering', 'Additive Manufacturing', 'ceramics', 'metal']
Selective Separation Sintering (SSS) A New Layer Based Additive Manufacturing Approach for Metals and Ceramics
Conference paper
https://repositories.lib.utexas.edu//bitstreams/11e1d9dd-64b8-485b-8bd1-26dfcc130b88/download
University of Texas at Austin
Selective Separation Sintering (SSS) is a powder layer based Additive Manufacturing approach. SSS can fabricate high temperature ceramic and metallic parts at comparatively lower cost with high quality. In the printing process a dry powder of higher sintering temperature is deposited into the base material which makes up the part. The inserted powder defines the boundary of the part and separates the part from its surroundings. When printing of all layers is completed the deposited dry powder serves as a separation coating which defines the shape of the part. In the sintering process the base material is sintered into a solid part while the separation coating remains as loose powder. The part is then separated from the surrounding area at the separation coating surfaces, and is post processed if necessary. Preliminary results have proven the capability of SSS in successfully printing ceramic and metallic parts. Future experiments are planned for improving the process resolution.
null
null
null
null
null
null
['Khoshnevis, Behrokh', 'Zhang, Jing']
2021-10-28T20:44:54Z
2021-10-28T20:44:54Z
2016
Mechanical Engineering
null
https://hdl.handle.net/2152/89696
eng
2016 International Solid Freeform Fabrication Symposium
Open
['selective separation sintering', 'SSS', 'sintering', 'powder deposition', 'additive manufacturing']
Selective Separation Sintering for Metallic Part Fabrication
Conference paper
https://repositories.lib.utexas.edu//bitstreams/5c5887cd-765b-484d-8a1d-563202856090/download
University of Texas at Austin
Selective Separation Sintering (SSS) is a powder layer based additive manufacturing approach. In the printing process a dry powder of higher sintering temperature is deposited into the base material which makes up the part. The inserted powder defines the boundary of the part and separates the part from its surroundings. A post sintering of the part is carried out in the furnace where the base material is sintered and the inserted powder remain loose due to its higher sintering temperature. The part is separated from the surrounding redundant material along the loose inserted powder region. A stable deposition rate of S-powder is the key for generating parts of easy separation and smooth surface. Factors that affect the flow rate are analyzed and the analyzed results are implemented to stabilize the process. With the progress in powder deposition rate control, bronze parts have been fabricated which demonstrate good quality.
null
null
null
null
null
null
['Bournias-Varotsis, A.', 'Friel, R.J.', 'Harris, R.A.', 'Engstrom, D.']
2021-11-01T21:59:46Z
2021-11-01T21:59:46Z
2016
Mechanical Engineering
null
https://hdl.handle.net/2152/89771
eng
2016 International Solid Freeform Fabrication Symposium
Open
['aluminum foils', 'insulating layer', 'embedded electronic circuits', 'electronic circuits', 'anodic aluminum oxide', 'ultrasonic additive manufacturing']
Selectively Anodised Aluminum Foils as an Insulating Layer for Embedding Electronic Circuitry in a Metal Matrix via Ultrasonic Additive Manufacturing
Conference paper
https://repositories.lib.utexas.edu//bitstreams/376e25f9-8bfe-4fd2-b2fc-9e0201334c25/download
University of Texas at Austin
Ultrasonic Additive Manufacturing (UAM) is a hybrid Additive Manufacturing (AM) process that involves layer-by-layer ultrasonic welding of metal foils and periodic machining to achieve the desired shape. Prior investigative research has demonstrated the potential of UAM for the embedding of electronic circuits inside a metal matrix. In this paper, a new approach for the fabrication of an insulating layer between an aluminium (Al) matrix and embedded electronic interconnections is presented. First, an Anodic Aluminium Oxide (AAO) layer is selectively grown onto the surface of Al foils prior to bonding. The pre-treated foils are then welded onto a UAM fabricated aluminium substrate. The bonding step can be repeated for the full encapsulation of the electronic interconnections or components. This ceramic AAO insulating layer provides several advantages over the alternative organic materials used in previous works.
null
null
null
null
null
null
['Crane, N.B.', 'Tuckerman, J.', 'Nielson, G.N.']
2021-09-30T20:25:31Z
2021-09-30T20:25:31Z
9/23/10
Mechanical Engineering
null
['https://hdl.handle.net/2152/88296', 'http://dx.doi.org/10.26153/tsw/15237']
eng
2010 International Solid Freeform Fabrication Symposium
Open
['additive manufacturing', 'biological growth', 'performance benefits', 'performance challenges', 'self-assembly errors', 'miniature thermoelectric devices', 'microscale photovoltaic cells']
Self Assembly as an Additive Manufacturing Process: Opportunities and Obstacles
Conference paper
https://repositories.lib.utexas.edu//bitstreams/f41f01b8-ea68-4f27-87b7-8cc83650f350/download
University of Texas at Austin
While additive manufacturing processes typically integrate functionally identical building blocks, biological growth depends on the precise assembly of molecular building blocks to achieve the remarkable functionality observed in living systems. This paper considers potential performance benefits and challenges of producing systems by controlled assembly of functional components. The work will consider the impact of self-assembly errors in two energy applications: miniature thermoelectric devices and microscale photovoltaic cells. In both, high performance is possible by assembling microscale components. While assembly errors can reduce system performance, performance models show that high levels of system performance can be achieved through system design and/or self-assembly process control.
null
null
null
null
null
null
['Nassar, A.R.', 'Spurgeon, T.J.', 'Reutzel, E.W.']
2021-10-12T21:51:09Z
2021-10-12T21:51:09Z
2014
Mechanical Engineering
null
['https://hdl.handle.net/2152/88750', 'http://dx.doi.org/10.26153/tsw/15684']
eng
2014 International Solid Freeform Fabrication Symposium
Open
['defect detection', 'directed-energy additive manufacturing', 'additive manufacturing', 'metals', 'optical emission spectroscopy']
Sensing Defects during Directed-Energy Additive Manufacturing of Metal Parts using Optical Emissions Spectroscopy
Conference paper
https://repositories.lib.utexas.edu//bitstreams/e487fbdf-212a-42c5-993f-bd58edc0a857/download
University of Texas at Austin
Critical components produced via additive manufacturing must be free of unwanted defects. While defects may be detectable after deposition using nondestructive testing techniques, detecting defects during the deposition process offers many benefits: it may enable users to interrupt deposition to repair the part, or to abort deposition to minimize further loss of time and material. Here, we present a method for real-time defect detection during directed-energy additive manufacturing of metals. The method utilized optical emission spectroscopy and a custom-built data acquisition and control infrastructure. It was implemented on a LENS MR-7 machine, and employed during manufacturing of Ti-6Al-4V components in which defects were intentionally introduced. Emission spectra were correlated with defect locations, determined via computed tomography and metallographic cross-sectioning. Preliminary results indicated that defect formation was correlated with atomic titanium (Ti I) and Vanadium (V I) emissions and that measurement of the line-to-continuum ratio for line emissions could be used for defect detection. Based on these findings, sensing strategies for defect detection and, potentially, in-situ-defect repair may be realizable.
null
null
null
null
null
null
['Fan, Zhiqiang', 'Phatak, Kaushik', 'Liou, Frank']
2020-02-21T16:04:29Z
2020-02-21T16:04:29Z
8/30/05
Mechanical Engineering
null
['https://hdl.handle.net/2152/80065', 'http://dx.doi.org/10.26153/tsw/7087']
eng
2005 International Solid Freeform Fabrication Symposium
Open
Laser Metal Deposition
Sensitivity Analysis of Process Parameters in Laser Deposition
Conference paper
https://repositories.lib.utexas.edu//bitstreams/ea8beb7e-d6df-49e0-82a2-36fd784c2b77/download
null
In laser cladding with powder injection process, process output parameters, including melt pool temperature and melt pool dimensions, are critical for part quality. This paper uses simulation and experiments to investigate the effect of the process input parameters: laser power, powder mass flow rate, and scanning speed on the output parameters. Numerical simulations and experiments are conducted using a factorial design. The results are statistically analyzed to determine the significant factors and their interactions. The simulation results are compared to experimental results. The quantitative agreement/disagreement is discussed and further research is outlined.
null
null
null
null
null
null
['Vasudevarao, Bharath', 'Natarajan, Dharma Prakash', 'Henderson, Mark', 'Razdan, Anshuman']
2019-09-23T15:55:41Z
2019-09-23T15:55:41Z
2000
Mechanical Engineering
null
['https://hdl.handle.net/2152/75946', 'http://dx.doi.org/10.26153/tsw/3045']
eng
2000 International Solid Freeform Fabrication Symposium
Open
Parameter
Sensitivity of RP Surface Finish to Process Parameter Variation 251
Conference paper
https://repositories.lib.utexas.edu//bitstreams/d1a23107-9fba-4ba0-8e8c-7a9156e975cc/download
null
In the rapid prototyping process, surface finish is critical as it can affect the part accuracy, reduce the post processing costs and improve the functionality of the parts. This paper presents an experimental design technique for determining the optimal surface finish of a part built by the Fused Deposition Modeling (FDM) process. The design investigates the effect of the parameters; build orientation, layer thickness, road width, air gap and model temperature on the surface finish. Experiments were conducted using a fractional factorial design with two levels for each factor. The results are statistically analyzed to determine the significant factors and their interactions. The significant factors, their interactions and the optimum settings are proposed.
null
null
null
null
null
null
['Liravi, Farzad', 'Das, Sonjoy', 'Zhou, Chi']
2021-10-19T15:36:53Z
2021-10-19T15:36:53Z
2014
Mechanical Engineering
null
https://hdl.handle.net/2152/89302
eng
2014 International Solid Freeform Fabrication Symposium
Open
['bottom-up stereolithography', 'bottom-up additive manufacturing', 'finite element analysis', 'separation force', 'cohesive delamination', 'optimization']
Separation Force Analysis Based on Cohesive Delamination Model for Bottom-Up Stereolithography Using Finite Element Analysis
Conference paper
https://repositories.lib.utexas.edu//bitstreams/65027874-7aaf-48f6-bc28-9b61f146b12b/download
University of Texas at Austin
Bottom-up (constrain-surface) Additive Manufacturing (AM) systems have been widely used in industry. Compared to traditional open-surface AM technology, properties like better vertical resolution, higher material filling rate, less production time, and less material waste make bottom-up AM technology a suitable candidate for fabrication of complex three dimensional materials with high accuracy. However during the pulling up stage, the substantial force generated between the formed part and the material container has high risk of breaking the part and therefore reduces the process reliability. In this paper, an optimization-based method is developed to model bottom-up AM process using finite element analysis (FEA). The FEA model is developed using ABAQUS to model the behavior of the cohesive delamination at the interface of the formed part and a hyper-elastic intermediate which has been used to reduce the pulling up force. An optimization model is also established to evaluate the cohesive stiffness parameters that cannot be calculated directly from closed formulas or mechanical tests. The results of this work will be used to develop an adaptive closed-loop mechanics-based system to control the pulling up process and achieve a reliable technology.
null
null
null
null
null
null
['Ljungblad, U.', 'Hultman, A.']
2021-09-30T13:40:06Z
2021-09-30T13:40:06Z
2010
Mechanical Engineering
null
['https://hdl.handle.net/2152/88246', 'http://dx.doi.org/10.26153/tsw/15187']
eng
2010 International Solid Freeform Fabrication Symposium
Open
['Electron Beam Melting', 'orthopedic implants', 'statistical process control']
Serial Production with EBM
Conference paper
https://repositories.lib.utexas.edu//bitstreams/6c0233d8-e8d8-4ef6-9199-7a6dc2248fb6/download
University of Texas at Austin
null
null
Moving from prototyping to production is a major challenge for the additive manufacturing industry. It requires a robust and reliable technology having high and verifiable repeatability. The transition into production is not possible without the technology being capable of sustaining a high product quality as well as productivity in par or better than traditional manufacturing. Electron Beam Melting (EBM) has since 2007, been used for manufacturing of CE-certified standard orthopedic implants with more than 20’000 units produced in several EBM systems. High productivity combined with process stability has been key factors for this application to emerge. Added product value in form of engineered surface porosity has been vital to promote the step into serial production. Development of EBM has been focused on system reliability, process stability, material quality, productivity and means for process validation to reach proven requirements for production. Statistical process control (SPC) has been a very powerful tool to carry out this development in an efficient way.
null
null
null
null
['Manzur, Tariq', 'Roychoudhuri, Chandra', 'Marcus, Harris']
2018-11-14T19:49:11Z
2018-11-14T19:49:11Z
1996
Mechanical Engineering
doi:10.15781/T21V5C03W
http://hdl.handle.net/2152/70258
eng
1996 International Solid Freeform Fabrication Symposium
Open
['CAD/CAM', 'SLS', 'SFF']
SFF Using Diode Lasers
Conference paper
https://repositories.lib.utexas.edu//bitstreams/28b8533e-977f-419a-b34d-8c1c12a9841f/download
null
Rapid prototypings using direct selective laser sintering (SLS) ofmetal/ceramic powders have a great potential for design and fabrication of near net shape ofmetal/ceramic parts. At presents CO2, Nd:YAG and Excimer are the only possible solutions for the heavy duty manufacturing applications. At the University ofConnecticut, researchers advanced the concept ofrapid prototyping and other desk top manufacturing tasks such as welding, sintering, drilling, marking, soldering of electronic components, face hardening ofmetal and other materials applications by the use ofhigh power diode lasers. Utilizing SLS techniques and approaches designed to harness the full potential of diode lasers, computer controlled sintering system was developed. The system is capable of producing complex three dimensional shapes ofmetal/ceramic parts from CAD/CAM solid model data files. In the paper direct sintered Fe-Bronze parts using high power laser diodes has been demonstrated. The system comprises ofhigh power laser diodes (25 W cw, A=980 nm and 60 W pulse or cw, A=81 0 nm), beam scanning systems, atmospheric controlled chamber, and CAD/CAM software.
null
null
null
null
null
null
['Xu, Anping', 'Shaw, Leon L.']
2020-02-17T14:19:56Z
2020-02-17T14:19:56Z
2004
Mechanical Engineering
null
['https://hdl.handle.net/2152/79995', 'http://dx.doi.org/10.26153/tsw/7020']
eng
2004 International Solid Freeform Fabrication Symposium
Open
['functionally graded materials', 'Equal distance offset', 'Solid freeform fabrication']
SFF-Oriented Modeling and Process Planning of Functionally Graded Materials Using a Novel Equal Distance Offset Approach
Conference paper
https://repositories.lib.utexas.edu//bitstreams/d293c4f7-1d4b-4a1e-9562-0a4339a57a01/download
null
This paper deals with the modeling and process planning of solid freeform fabrication (SFF) of 3D functionally graded materials (FGMs). A novel approach of representation and process planning of FGMs, termed as equal distance offset (EDO), is developed. In EDO, a neutral arbitrary 3D CAD model is adaptively sliced into a series of 2D layers. Within each layer, 2D material gradients are designed and represented via dividing the 2D shape into several sub-regions enclosed by iso-composition contours. If needed, the material composition gradient within each of sub-regions can be further determined by applying the equal distance offset algorithm to each sub-region. Using this approach, an arbitrary-shaped 3D FGM object with linear or non-linear composition gradients can be represented and fabricated via suitable SFF machines.
null
null
null
null
null
null
['Bernitsas, Michael M.', 'Suryatama, Danet', 'Byungsik, Kang', 'Dale, G. Karr']
2018-10-03T15:59:04Z
2018-10-03T15:59:04Z
1994
Mechanical Engineering
doi:10.15781/T2R78676V
http://hdl.handle.net/2152/68656
eng
1994 International Solid Freeform Fabrication Symposium
Open
['LEAP Theory', 'selective laser sintering', 'Solid free-form fabrication']
Shape and Topology Structural Redesign by Large Perturbations
Conference paper
https://repositories.lib.utexas.edu//bitstreams/19cd8728-dc10-4270-a38f-4728e445b56d/download
null
The ultimate goal in concurrent engineering of structures is to achieve simultaneously in the design stage the following objectives: (1) A shape that performs itsfunction, conforms with the boundary conditions,and can support the external loads. (2) A product with structural integrity, i.e. with stress levels remaining below acceptable limits. (3) A product with acceptable performance, e.g. modal dynamics, i.e. with natural frequencies and mode shapes that do not amplify external dynamic loads; and static, i.e. acceptable deflection. (4) A composite microstructure that can optimally satisfy the above topology/ shape, load, and performance constraints. (5) A microstructurefabrication process that efficiently produces the above optimal structure. The purpose of our ONR funded project is to address the complete problem in concurrent structural design by further developing the LargE Admissible Perturbations (LEAP) theory which is being developed at the University of Michigan since 1983, and combiningit with micromechanicsconstitutive equations. At the fabrication end, the Selective Laser Sintering (SLS) process will be simulated so that the SLS variables are defined as the final product of the concurrent structuraLdesign optimization process. LEAP theory -- as implemented in Code RESTRUCT (REdesign of STRUCTures) -- produces the final design without trial and error or repeated Finite Element Analyses (FEAs), thus, shortening the redesign process and contributing to rapid prototyping.
null
null
null
null
null
null
['Merz, R.', 'Prinz, F.B.', 'Ramaswami, K.', 'Terk, M.', 'Weiss, L.E.']
2018-09-26T15:47:56Z
2018-09-26T15:47:56Z
1994
Mechanical Engineering
doi:10.15781/T2BK1781C
http://hdl.handle.net/2152/68579
eng
1994 International Solid Freeform Fabrication Symposium
Open
['Department of Mechanical Engineering', 'CAD/CAM', 'SFF', 'Shape Deposition']
Shape Deposition Manufacturing
Conference paper
https://repositories.lib.utexas.edu//bitstreams/8ddbfacb-0827-4a15-9fe6-3a149ff24c7e/download
null
One challenge for solid freeform fabrication has been to develop the capability to directly create functional metal shapes which are dense, metallurgically bonded, geometrically accurate and with good surface appearance. Shape Deposition is a manufacturing paradigm which attempts to address these issues. It incorporates the advantages of several processes including solid freeform fabrication (complex geometries, rapidly planned), 5-axis CNC machining (accuracy, smooth surfaces), shot-peening (for stress relief) and 'microcasting' (a high-performance, weldbased material deposition process). These processes are integrated within a CAD/CAM system using robotic automation. This paper will present the current research in this effort.
null
null
null
null
null
null
['Weiss, L.', 'Prinz, F.', 'Neplotnik, G.', 'Padmanabhan, K.', 'Schultz, L.', 'Merz, R.']
2018-11-08T19:39:06Z
2018-11-08T19:39:06Z
1996
Mechanical Engineering
doi:10.15781/T2MG7GF74
http://hdl.handle.net/2152/69916
eng
1996 International Solid Freeform Fabrication Symposium
Open
['SDM', 'SFF', 'manufacturing process']
Shape Deposition Manufacturing of Wearable Computers
Conference paper
https://repositories.lib.utexas.edu//bitstreams/85ac1852-f05c-402c-9911-5f9ff302b0a1/download
null
Shape Deposition Manufacturing (SDM) is a solid freefrom fabrication methodology which can fabricate heterogeneous structures, i.e., multi-material structures with embedded components. One application is to build-up electromechanical devices such as conformally shaped computer packages with embedded electronics. The goal is to be able to quickly design and manufacture, in small lots, personalized, rugged units for specialized applications. One example, which is described in this paper, is the manufacture of an underwater computer, the 'Frogman', which is built-up in layers of polyurethane.
null
null
null
null
null
null
['Zhou, Wenchao', 'Loney, Drew', 'Fedorov, Andrei G.', 'Degertekin, F. Levent', 'Rosen, David W.']
2021-10-04T21:44:23Z
2021-10-04T21:44:23Z
8/17/11
Mechanical Engineering
null
['https://hdl.handle.net/2152/88358', 'http://dx.doi.org/10.26153/tsw/15297']
eng
2011 International Solid Freeform Fabrication Symposium
Open
['ink-jet printing', 'droplet deposition', 'droplet impact']
Shape Evolution of Droplet Impingement Dynamics in Ink-Jet Manufacturing
Conference paper
https://repositories.lib.utexas.edu//bitstreams/1346c739-c744-46a4-90c9-d9e0aece91b4/download
University of Texas at Austin
Ink-jet printing enables more efficient, economic, scalable manufacturing for a wide variety of materials than other traditional additive techniques. The impact of droplets onto a substrate is critical for accuracy control and optimization of the droplet deposition process. However, most previous research about droplet impact focused on the spreading radius of the droplet, which does not provide enough information for manufacturing purposes. This paper presents new methods to model and characterize droplet shape change during impact so that the droplet deposition process can be optimized to build desired geometries. A validated numerical model is used to study the shape change of the droplet impingement on a solid surface. A dimensional analysis is conducted to reduce the number of parameters of the impact conditions by matching Reynolds, Weber, and Froude numbers as well as possible. In addition, a new method of characterizing droplet shape is presented that measures its similarity to a desired shape. The shape evolution of a wide range of impact conditions is simulated with the validated numerical model using both physical and dimensionless quantities. The effects of the dimensionless numbers on the shape evolution are examined and analyzed. Successive multiple droplets impact is also simulated.
null
null
null
null
null
null
['Utela, B.', 'Anderson, R.', 'Kuhn, H.', 'Ganter, M.']
2020-03-09T15:14:25Z
2020-03-09T15:14:25Z
8/21/07
Mechanical Engineering
null
['https://hdl.handle.net/2152/80194', 'http://dx.doi.org/10.26153/tsw/7213']
eng
2007 International Solid Freeform Fabrication Symposium
Open
Three Dimensional Printing
Shape Training of Nitinol Wire Using Three-Dimensional (3DP) Fixtures
Conference paper
https://repositories.lib.utexas.edu//bitstreams/401afcbd-4a4f-4ae5-ab95-86c439242682/download
null
The presented research focuses on work done at the University of Washington on process development for the training of nitinol shape memory alloy wire using Three Dimensional Printing (3DP). Fixtures are created using the commercial stainless steel printing system produced by Ex One. Superelastic nitinol wire is set by restraining the wire in a fixture and thermal processing. A two dimensional test array was designed and fabricated to examine the effects of fixture curvature on the final wire shape. Three dimensional coils and spheres were created to demonstrate the potential of this process for more complicated shapes.
null
null
null
null
null
null
['Yang, Li', 'Harrysson, Ola', 'West, Harvey', 'Cormier, Dennis']
2021-10-21T19:14:10Z
2021-10-21T19:14:10Z
2015
Mechanical Engineering
null
https://hdl.handle.net/2152/89426
eng
2015 International Solid Freeform Fabrication Symposium
Open
['auxetic structure', 're-entrants', 'shear properties', 'electron beam melting']
Shear Properties of the Re-Entrant Auxetic Structure Made via Electron Beam Melting
Conference paper
https://repositories.lib.utexas.edu//bitstreams/ae906d6b-cffe-4744-bf25-af438bcb82be/download
University of Texas at Austin
While the tensile/compressive mechanical properties of the re-entrant auxetic cellular structure have been relatively well modeled, their shear properties including the shear modulus and shear strength have not been investigated. This paper focuses on the analytical modeling of the shear properties of this auxetic structure utilizing beam analysis. The modeling results were further compared with results from both simulation and experimentation. It was found that in addition to the effective length reduction effect, the size effect also becomes significant for the shearing of this re-entrant auxetic structures. Due to the size effect, it was expected that the re-entrant auxetic structure could not be effectively homogenized based on the developed analytical property model, and additional design factors must be considered in the future.
null
null
null
null
null
null
Steinchen, W.
2018-11-02T16:53:55Z
2018-11-02T16:53:55Z
1995
Mechanical Engineering
doi:10.15781/T2891294T
http://hdl.handle.net/2152/69340
eng
1995 International Solid Freeform Fabrication Symposium
Open
['strain analysis', 'vibration isolation', 'optimization']
Sheareography - a Practical Optical Testing and Measuring Method
Conference paper
https://repositories.lib.utexas.edu//bitstreams/27b4222f-ea28-4dc0-995e-6aa491a4f66c/download
null
Shearography is a laser optical method which is suited for either nondestructive testing or for strain analysis. Contrary to holography which measures surfach displacements, shearography measures derivatives of surface displacements. Since strains are functions of displacement derivatives, shearography allows strains to be determined without numerical differentiating displacement data. Defects in object normally create strain concentrations; it is easier using shearography to correlate defects with strain anomalies rather than displacement anomalies applying holography. Furthermore, rigid body motions do not produce strain, thus shearography is insensitive against such motions and does not need adopting any particular device for vibration isolation. It is an industrial tool suited very well for the following ares: 1. strain measurement and strain analysis 2. nondestructive testing and quality assurance system 3. optimization ofmachine parts and structures of any material
null
null
null
null
null
null
['Kletetzka, I.', 'Klippstein, H.', 'Sural, I.', 'Schmid, H.-J.']
2023-03-29T16:16:58Z
2023-03-29T16:16:58Z
2022
Mechanical Engineering
null
['https://hdl.handle.net/2152/117676', 'http://dx.doi.org/10.26153/tsw/44555']
eng
2022 International Solid Freeform Fabrication Symposium
Open
laser sintering
Shelf Life of Polyamide 12 (PA2200) Laser Sintering Powder
Conference paper
https://repositories.lib.utexas.edu//bitstreams/0240d80f-fdb1-403d-8551-46ba427136d1/download
null
It is a very well-known fact that polyamide powders age during processing in laser sintering. Therefore, the recycling rate of used powder is typically limited to around 50 % and it has to be mixed with new, virgin powder, before the next build job can be started. The aging of the polymer powder between its production and processing, in contrast, has hardly been investigated so far and has received little attention. In order to investigate the effects of storage time, optical, thermal and rheological tests were carried out on two batches of PA2200 powder, which had been stored for 5.5 and 6.5 years respectively. Compared to freshly produced powders, aging effects were clearly visible.
null
null
null
null
null
null
['Yao, W. L.', 'Leu, Ming C.']
2019-02-25T17:45:13Z
2019-02-25T17:45:13Z
1998
Mechanical Engineering
null
['https://hdl.handle.net/2152/73477', 'http://dx.doi.org/10.26153/tsw/627']
eng
1998 International Solid Freeform Fabrication Symposium
Open
['Rapid Prototyping', 'Investment Casting']
Shell Cracking In Investment Casting with Laser Stereolithography Patterns
Conference paper
https://repositories.lib.utexas.edu//bitstreams/38b318eb-09a7-4930-b162-482f82a5ceef/download
null
This paper presents an investigation of ceramic shell cracking during the burnout process in investment casting with internally webbed laser stereolithography patterns. We hypothesize that shell cracking will occur when the rupture temperature of the ceramic shell is lower than both the glass transition temperature of the pattern material and the web· link buckling temperature. The hypothesis is validated by our experimental observations which confirm the numerical predictions from our fillite element analysis. This provides a basis for design of the internal web geometry of a lithography pa.tternand evaluation ofthe burnolltprocesswithsuch a pattern. We show the shell cracking and web link buckling temperatures to be functiollsofthe pattern geometry (including the cross~sectional dimensions and span length of the web link) and the shell thickness.
null
null
null
null
null
null
['Dilip, J.J.S.', 'Anam, Md Ashabul', 'Pal, Deepankar', 'Stucker, Brent']
2021-10-28T21:11:22Z
2021-10-28T21:11:22Z
2016
Mechanical Engineering
null
https://hdl.handle.net/2152/89702
eng
2016 International Solid Freeform Fabrication Symposium
Open
['additive manufacturing', 'selective laser melting', 'alloy IN625', 'single track deposits']
A Short Study on the Fabrication of Single Track Deposits in SLM and Characterization
Conference paper
https://repositories.lib.utexas.edu//bitstreams/66e18862-6618-4434-b47e-ea737d9fb564/download
University of Texas at Austin
The present investigation is focused on fabrication of single track deposits, with multiple laser power and scan speed combinations to turn understanding their effect on the formation of the melt pool. In this study alloy, IN625 powder from EOS was used to produce single track deposits. Surface morphology and dimensions of single track deposits were characterized using SEM. The cross-section of the single track deposits was studied, and the geometrical features of melt pools were evaluated. The results indicate that melt pool characteristics provide significant information that is helpful for process parameters selection. These single track experiments will be being extended to fabricate samples with multiple layers in the future study. This approach of investigating single track deposits, when used to narrow down the window of process parameters can provide a path to speed up the tedious and time-consuming experiments for optimization of process parameters.
null
null
null
null
null
null
['McIntosh, Joseph J.', 'Danforth, Stephen C.', 'Jamalabad, Vikram R.']
2018-11-29T20:20:48Z
2018-11-29T20:20:48Z
1997
Mechanical Engineering
doi:10.15781/T2513VG0Q
http://hdl.handle.net/2152/70338
eng
1997 International Solid Freeform Fabrication Symposium
Open
['CAD', 'SLS']
Shrinkage and Deformation in Components Manufactured by Fused Deposition of Ceramics
Conference paper
https://repositories.lib.utexas.edu//bitstreams/8ccc53e8-a835-4750-9431-5a35f3953900/download
null
Fused Deposition of Ceramics (FDC) presents a new processing technique that may contribute to anisotropic shrinkage and deformation, which are critical issues in the manufacture of ceramic components. The aim ofthis study is to identify and quantify key FDC parameters and their influence on shrinkage and deformation. The study was divided into two focus areas. The first was the effect ofthe FDC build parameters on the shrinkage of ceramic parts. The second focused on the interaction of the FDC build process with the geometrical features of a part. A series of experimental design techniques have been implemented in order to gain a thorough understanding of said parameters, as well as any possible interactions between parameters Studies have been conducted across each processing step, from the green manufacture of the part, through binder removal, and sintering. The data and knowledge gained from these experiments will allow us to redesign the original CAD component files to compensate for the shrinkage and deformation encountered when using the FDC technique
null
null
null
null
null
null
['Bhargava, P.', 'Bandyopadhyay, A.', 'Rangarajan, S.', 'Qi, G.', 'Dai, C.', 'Wu, S.', 'Danforth, S.', 'Safari, A.']
2018-12-05T19:53:23Z
2018-12-05T19:53:23Z
1997
Mechanical Engineering
doi:10.15781/T2WS8J63V
http://hdl.handle.net/2152/71407
eng
1997 International Solid Freeform Fabrication Symposium
Open
['FDC', 'heating schedule']
Shrinkage, Weight Loss and Crack Prevention During Binder Burn Out of Components Produced" by Fused Deposition of Ceramics (FDC)
Conference paper
https://repositories.lib.utexas.edu//bitstreams/483638ce-bfc2-44a1-9110-444bbb302e94/download
null
In the present study the sequential stages ofthe previously established binder bum out (BBO) route were characterized by obtaining precise shrinkage and weight loss measurements from interrupted runs. A DoE (Design of Experiments) approach was adopted to systematically investigate the effect of process variables; such as the heating rates during critical segments, part dimensions and environment (flowing nitrogen vs vacuum) on the shrinkage, weight loss and cracking during binder bum out. A stepwise TGA was performed to study the effect of ramp rate and dwell time on the kinetics of binder bum out, and an experiment was conducted to determine optimum wicking conditions. The results from this study have been used to maximize the weight loss and minimize the cracking during binder bum out cycle for FDC parts with different sizes.
null
null
null
null
null
null
['Stierlen, Peter', 'Schanz, Peter', 'Eyerer, Peter']
2019-02-26T20:39:02Z
2019-02-26T20:39:02Z
1998
Mechanical Engineering
null
['https://hdl.handle.net/2152/73499', 'http://dx.doi.org/10.26153/tsw/649']
eng
1998 International Solid Freeform Fabrication Symposium
Open
['high density ceramic structure', 'carbon binding structure']
Si/SiC-Ceramic low process shrinkage - high temperature material for the Laser Sinter process
Conference paper
https://repositories.lib.utexas.edu//bitstreams/f8a8b6ba-df71-46ea-96e1-5bc6ad0c4a9c/download
null
Actual RP-systemsare very limited in producing adequate ceramic prototypes. In the presented process, the SiC..green part manufacturing bythe laser sintering process in combination with special postprocessing allows the fast production of SUSiC prototypes. A mixture of SiC powder and a reactive polymer binder system is used in the Laser Sinter process. In the following postprocessing the porous green part has to be .infiltrated with a precursor resin, carbonised and finally infiltrated withimolten silicon.•Incontrast to cold isostatic moulding or slip casting the shrinkage is very low (2-4 0/0).• Experiments with suitable materials/and process conditions were successful. This paper will show the state of and the possible further investigation into process.
null
null
null
null
null
null
['Stierlen, Peter', 'Eyerer, Peter']
2019-03-12T20:01:05Z
2019-03-12T20:01:05Z
1998
Mechanical Engineering
null
['https://hdl.handle.net/2152/73608', 'http://dx.doi.org/10.26153/tsw/750']
eng
1999 International Solid Freeform Fabrication Symposium
Open
['precursor·resin', 'silicon']
Si/SiC-Ceramic Prototypes via LS2I-Process (Liquid Silicon Infiltration of Laser Sintered C-SiC Parts)
Conference paper
https://repositories.lib.utexas.edu//bitstreams/c4061c09-873d-4fd5-9b93-2d9d02d66fa5/download
null
The liquid silicon infiltration of laser sinteredC-~iC parts (LS2 I) is solidfreeform fabrication technique which allows the production of complexshapedSi/SiC prototypes. A mixture of SiC powder and reactive polymer binder isused in the las~r sinteringprocessto generate a porous green part. In the\postprocessing, the porous green part structure has to be infiltrated with a.precursor·resin, carbonised and finally·.infiltrated•. with molten silicon. The infiltrated silicon reacts with the residualcarbontobuild~~SiC.Results generated by the use of reduced primary particle sizes as well asaltemative infiltration materials and the use of other·RPtechniquesfor the green partfabrication will be discussed in this paper.
null
null
null
null
null
null
['Melvin III, Lawrence S.', 'Beaman Jr., Joseph J.']
2018-11-08T15:39:49Z
2018-11-08T15:39:49Z
1995
Mechanical Engineering
doi:10.15781/T2FX74H89
http://hdl.handle.net/2152/69891
eng
1995 International Solid Freeform Fabrication Symposium
Open
['powder application', 'bed density experiment', 'sieve feed system']
A Sieve Feed System for the Selective Laser Sintering Process
Conference paper
https://repositories.lib.utexas.edu//bitstreams/303042ca-d234-414d-aeab-1d1d1438758e/download
null
A sieve feed system has been designed for use with the Selective Laser Sintering process. The sieve feed system uses electrostatic charge to help apply polymer powder to a green powder bed. The sieve feed system was found to help the application of polymer powder as measured by a 10 to 15% increase in final part density. The sieve feed system has many potential applications, including material property design, and material mixing during the sintering process.
null
null
null
null
null
null
['Taft, Douglas', 'Ogale, Amod', 'Paul, Frank', 'Hunt, Elaine', 'Ahzi, Said']
2018-12-05T17:11:39Z
2018-12-05T17:11:39Z
1997
Mechanical Engineering
doi:10.15781/T2XS5K333
http://hdl.handle.net/2152/71399
eng
1997 International Solid Freeform Fabrication Symposium
Open
['StereoLithography', 'solid models']
Silica Filled Resins for Rapid SLA Tools
Conference paper
https://repositories.lib.utexas.edu//bitstreams/507d2a5d-7432-4538-905c-1d2adb898d06/download
null
A stable silica /SL epoxy resin suspension has been developed at Clemson University. It has been processed to make parts in a commercial StereoLithography Apparatus (SLA). Results oftesting show that the composite material has a higher modulus and increased abrasion resistance over the neat epoxy resin. An injection molding die has been made with the reinforced resin in the SLA and tested.
null
null
null
null
null
null
['Mi, Jian', 'Gillespie, Josh', 'Johnson, Ryan W.', 'Bondi, Scott N.', 'Lackey, W. Jack']
2019-11-21T18:22:08Z
2019-11-21T18:22:08Z
2003
Mechanical Engineering
null
['https://hdl.handle.net/2152/78556', 'http://dx.doi.org/10.26153/tsw/5612']
eng
2003 International Solid Freeform Fabrication Symposium
Open
Silicon Carbide
Silicon Carbide Growth Using Laser Chemical Vapor Deposition
Conference paper
https://repositories.lib.utexas.edu//bitstreams/fb3821c8-ce1f-48bc-b2cc-b8e38d00f41a/download
null
Silicon Carbide (SiC) has been grown from methyltrichlorosilane (MTS) and hydrogen using the Georgia Tech Laser Chemical Vapor Deposition (LCVD) system. A morphology study of LCVD-SiC fibers and lines was completed. Graphite and single crystal silicon were used as the substrates. In order to provide guidance to future growth of SiC, thermodynamic calculations for the C-H-Si-Cl system were performed using the SOLGASMIX-PV program.
null
null
null
null
null
null
['Vail, N.K.', 'Barlow, J.W.', 'Marcus, H.L.']
2018-05-03T19:06:51Z
2018-05-03T19:06:51Z
1993
Mechanical Engineering
doi:10.15781/T25X25W7S
http://hdl.handle.net/2152/65059
eng
1993 International Solid Freeform Fabrication Symposium
Open
['Selective Laser Sintering', 'SLS', 'Department of Chemical Engineering', 'Center for Materials Science and Engineering', 'Silicon Carbide', 'Encapsulation', 'Polymer', 'Composites']
Silicon Carbide Preforms for Metal Infiltration by Selective Laser Sintering™ of Polymer Encapsulated Powders
Conference paper
https://repositories.lib.utexas.edu//bitstreams/de3d507b-e987-44c3-bf3d-f1fa765acc96/download
null
A polymer encapsulated silicon carbide system has been developed for use with Selective Laser Sintering. Extensive studies with this material have provided information pertaining to processing and material parameters which most affect the strengths and densities of resulting green parts. The important parameters considered were particle size distribution of the powders, laser scanning conditions, and laser beam diameter. Simple and complex shapes were easily produced with this material using optimized parameters. Green objects were infused with metal by Lanxide using their pressureless infiltration process to produce both metal matrix and ceramic matrix composites. (Key Words: Silicon Carbide, Encapsulation, Polymer, Selective Laser Sintering, Composites).
null
null
null
null
null
null
['Birmingham, B.R.', 'Tompkins, J.V.', 'Marcus, H.L.']
2018-10-03T18:19:38Z
2018-10-03T18:19:38Z
1994
Mechanical Engineering
doi:10.15781/T22J68P93
http://hdl.handle.net/2152/68669
eng
1994 International Solid Freeform Fabrication Symposium
Open
['SALDVI', 'selected laser area deposition', 'solid freeform fabrication']
Silicon Carbide Shapes By Selected Area Laser Deposition Vapor Infiltration
Conference paper
https://repositories.lib.utexas.edu//bitstreams/efc3902b-fd12-4374-b248-af1b996d95b1/download
null
Selected Area Laser Deposition Vapor Infiltration (SALDVI) is a unique combination ofselected area laser deposition, chemical vapor infiltration and layered powder handling techniques that can be used to fabricate silicon carbide (SiC)/SiC composite shapes. This paper discusses a SALDVI process under investigation which selectively infiltrates SiC powder with SiC generated by decomposition of a gas precursor under a scanned laser beam. A general description of the process, including some of its inherent advantages is presented. Experimental results which explore beam interaction, powder size and infiltration time effects are also presented.
null
null
null
null
null
null
['Flach, Lawrance', 'Chartoff, Richard P.']
2018-10-03T15:36:15Z
2018-10-03T15:36:15Z
1994
Mechanical Engineering
doi:10.15781/T2NG4HB3F
http://hdl.handle.net/2152/68649
eng
1994 International Solid Freeform Fabrication Symposium
Open
['Polymer shrinkage', 'stereolithography', 'Photopolymerization']
A Simple Polymer Shrinkage Model Applied to Stereolithography
Conference paper
https://repositories.lib.utexas.edu//bitstreams/6796957d-2c6b-4a2e-8a76-619c18df2c58/download
null
A simple polymer shrinkage model has been successfully applied to the stereolithography process. The shrinkage model, which computes specific volume changes from the degree of conversion of monomer to polymer, incorporates a lag between conversion and shrinkage. An overall process model used to simulate the stereolithography process was modified by inclusion of the shrinkage model. Use of the modified stereolithography process model allows prediction of the shrinkage that might be expected to occur when fabricating a strand of plastic. By varying the lag between conversion and shrinkage it is shown that faster shrinking resins should exhibit lower overall shrinkage than slower shrinking resins. This is a direct result of the fact that less shrinkage occurs after the strand has been scanned for the faster shrinking resins.
null
null
null
null
null
null
['Karunakaran, K. P.', 'Solanki, P. D.', 'Sahasrabudhe, Onkar S.', 'Pushpa, Vishal', 'Dwivedi, Rajeev', 'Kovacevic, Radovan']
2020-02-24T15:01:18Z
2020-02-24T15:01:18Z
2005
Mechanical Engineering
null
['https://hdl.handle.net/2152/80077', 'http://dx.doi.org/10.26153/tsw/7098']
eng
2005 International Solid Freeform Fabrication Symposium
Open
Rapid Prototyping
Simplified Production of Large Prototypes using Visible Slicing
Conference paper
https://repositories.lib.utexas.edu//bitstreams/3e33460f-7a79-40de-b0ab-8a48375b2318/download
null
Rapid Prototyping (RP) is a totally automatic generative manufacturing technique based on a “divide-and-conquer” strategy called ‘slicing’. Simple slicing used on 2.5-axis kinematics of the existing RP machines is responsible for the staircase error. Although thinner slices will have less error, the slice thickness has practical limits. Visible Slicing overcomes these limitations. A few visible slices exactly represent the object. Each visible slice can be realized using a 3- axis kinematics machine from two opposite directions. Visible slicing is implemented on Segmented Object Manufacturing (SOM) machine under development. SOM can produce soft large prototypes faster and cheaper with accuracy comparable to that of CNC machining.
null
null
null
null
null
null
['Flood, Aaron', 'Liou, Frank']
2021-11-18T17:40:01Z
2021-11-18T17:40:01Z
2019
Mechanical Engineering
null
['https://hdl.handle.net/2152/90442', 'http://dx.doi.org/10.26153/tsw/17363']
eng
2019 International Solid Freeform Fabrication Symposium
Open
['laser beam quality', 'laser beam distance', 'Ti-64', 'aluminum', 'steel', 'blown powder', 'metal additive manufacturing']
Simulated Effect of Laser Beam Quality on the Robustness of Laser-Based AM System
Conference paper
https://repositories.lib.utexas.edu//bitstreams/4650a2a1-d050-4fbc-9d8b-be4f91841594/download
University of Texas at Austin
In many metal AM techniques, a laser is used as the heat source and in some applications, it can be advantageous to work off of the focal plane. When operating outside of focus, the beam quality of the laser can have drastic impacts on the ability to manufacture quality parts. This study investigates the effect of the beam quality and distance from the focal plan on the ability to deposit Ti-64, aluminum, and steel through the simulation of the blown powder process.
null
null
null
null
null
null
['Costa, L.', 'Vilar, R.', 'Réti, T.']
2020-02-17T15:03:30Z
2020-02-17T15:03:30Z
2004
Mechanical Engineering
null
['https://hdl.handle.net/2152/80004', 'http://dx.doi.org/10.26153/tsw/7029']
eng
2004 International Solid Freeform Fabrication Symposium
Open
Multilayer laser powder deposition
Simulating the Effects of Substrate Pre-Heating on the Final Structure of Steel Parts Built by Laser Powder Deposition
Conference paper
https://repositories.lib.utexas.edu//bitstreams/ea036650-8ed0-4efa-b3d7-013be6c8ae8e/download
null
Tool steel parts built by laser powder deposition often present a heterogeneous distribution of properties caused by the complex structural transformations that occur during the deposition process. A model describing these transformations has been developed. It couples finite element heat transfer calculations with transformation kinetic theory to predict the final microstructure and properties of the material and their variation across a laser powder deposited part. Pre-heating is often used to reduce the residual stresses and the risk of thermal distortion and cracking. However, this changes the heat transfer conditions and affects the final microstructure and properties. In this work the proposed model was used to evaluate the effects of substrate preheating on the final hardness distribution. The results show that the final hardness depends considerably on the initial temperature of the substrate.
null
null
null
null
null
null
['López, Omar', 'Martínez-Hernández, Uriel', 'Ramírez, José', 'Pinna, Christophe', 'Mumtaz, Kamran']
2021-10-26T18:46:03Z
2021-10-26T18:46:03Z
2016
Mechanical Engineering
null
https://hdl.handle.net/2152/89554
eng
2016 International Solid Freeform Fabrication Symposium
Open
['Cellular Automata - Finite Element', 'CA-FE', 'AA-2024', 'microstructure', 'selective laser melting']
Simulating the Microstructural Evolution of a Selective Laser Melted AA-2024
Conference paper
https://repositories.lib.utexas.edu//bitstreams/cc17bba6-d9b0-45fb-a1d6-16040789146b/download
University of Texas at Austin
A two-dimensional Cellular Automata (CA) – Finite Element (FE) (CA-FE) coupled model has been developed in order to predict the microstructure formed during melting of a powdered AA-2024 feedstock using the Additive Manufacturing (AM) process Selective Laser Melting (SLM). The presented CA model is coupled with a detailed thermal FE model computing heat flow characteristics of the SLM process. The developed model takes into account the powder-to-liquid-to-solid transformation, tracks the interaction between several melt pools within a melted track, and several tracks within various layers. It was found that the simulated microstructures bared a close resemblance with fabricated AA-2024 SLM samples. With these observed capabilities of the model, the porosity within a SLM produced part can be predicted, and used to optimise the fabrication parameters of a sample.
null
null
null
null
null
null
['Childs, T.H.C.', 'Hauser, C.', 'Taylor, C.M.', 'Tontowi, A.E.']
2019-09-20T18:21:07Z
2019-09-20T18:21:07Z
2000
Mechanical Engineering
null
['https://hdl.handle.net/2152/75925', 'http://dx.doi.org/10.26153/tsw/3024']
eng
2000 International Solid Freeform Fabrication Symposium
Open
Sintering
Simulation and Experimental Verification of Crystalline Polymer and Direct Metal Selective Laser Sintering 100
Conference paper
https://repositories.lib.utexas.edu//bitstreams/fcbec39b-777c-4397-a2b2-5382707b4bca/download
null
A previously developed two-dimensional finite element simulation of the SLS of amorphous polymers has been extended to the study of crystalline polymers and metals. For crystalline polymers, three developments have been needed: the treatment of latent heat of melting, the modifying of a viscous densification law to allow for the crystalline fraction of material during melting and, to obtain agreement with experiments, a consideration of the absorption depth of CO2 laser radiation into the powder bed; but the two-dimensional treatment remains sufficient. For metals, a different densification law and three-dimensional modelling have been needed for agreement with experiments on stainless steel powder beds.
null
null
null
null
null
null
['Kellner, I.N.', 'Zaeh, M.F.']
2021-09-30T19:52:18Z
2021-09-30T19:52:18Z
2010
Mechanical Engineering
null
['https://hdl.handle.net/2152/88287', 'http://dx.doi.org/10.26153/tsw/15228']
eng
2010 International Solid Freeform Fabrication Symposium
Open
['Additive Layer Manufacturing', '3D inkjet printing', 'polymerization', 'product quality', 'multi-scale simulation models', 'material design', 'process design']
Simulation Models for 3D Inkjet Printing – Material and Process Design
Conference paper
https://repositories.lib.utexas.edu//bitstreams/4652b1e3-6cec-4a98-b434-05f4dce9f0be/download
University of Texas at Austin
Due to the ability to produce complex parts with no need for pre-tooling, Additive Layer Manufacturing (ALM) is a future technology with 3D inkjet printing being one of them. The latter is based on the polymerization of a liquid dispensed into a powder bed. However, the special challenges which have to be met here are to increase product quality such as tensile strength and density on a repeatable base. Consequently multi-scale simulation models were developed to support material researchers as well as users of the technology in their daily work and therefore to contribute to process stability and material reliability of 3D printers and their products.
null
null
null
null
null
null
['Tikare, Veena', 'Griffith, Michelle', 'Schlienger, Eric', 'Smugeresky, John']
2018-12-07T17:08:46Z
2018-12-07T17:08:46Z
1997
Mechanical Engineering
doi:10.15781/T2GF0NG8W
http://hdl.handle.net/2152/71450
eng
1997 International Solid Freeform Fabrication Symposium
Open
['microstructures', 'SEM micrograph']
Simulation Of Coarsening During Laser Engineered Net Shaping
Conference paper
https://repositories.lib.utexas.edu//bitstreams/b2791c2a-cd9e-465c-9db4-e9969045d610/download
null
Laser Engineered Net_Shaping, otherwise known as LENSTM, is an advanced manufacturing technique used to fabricate complex near net shaped components directly from engineering solid models without the use of dies or machining. The ultimate objective ofthis project is to develop predictive simulation capability which will allow the LENSTM processors to determine fabrication conditions given the material, shape, and application ofthe final part. In this paper, we will present an incremental achievement to meeting the ultimate goal, a model capable ofsimulating the coarsening ofmicrostructural features under the unique thermal history to which a LENSTM part is subjected during processing. The simulation results show how grains ofvery different shapes and sizes form within the same deposition line. They also show that relatively minor changes in the dynamic temperature profile results in microstructures with vastly different characteristics. The implications ofthis work for LENSTM fabrication is that controlling the temperature profile is essential to tailoring the microstructure of a component to its application.
null
null
null
null
null
null
['Yan, Lei', 'Li, Wei', 'Chen, Xueyang', 'Zhang, Yunlu', 'Newkirk, Joe', 'Liou, Frank', 'Dietrich, David']
2021-10-27T21:31:01Z
2021-10-27T21:31:01Z
2016
Mechanical Engineering
null
https://hdl.handle.net/2152/89621
eng
2016 International Solid Freeform Fabrication Symposium
Open
['cooling rate', 'crack formation', 'direct laser deposition', 'Ti-48Al-2Cr-2Nb']
Simulation of Cooling Rate Effects on Ti-48Al-2Cr-2Nb Crack Formation in Direct Laser Deposition
Conference paper
https://repositories.lib.utexas.edu//bitstreams/9ad7e2dd-485d-4dee-a28c-7b6ed1fc1152/download
University of Texas at Austin
Transient temperature history is vital in direct laser deposition (DLD) because it reveals the cooling rate at specific temperatures, which directly relates to phase transformation and types of microstructure formed in deposit. FEA simulation was employed to study the transient temperature history and cooling rate at different experimental setups in Ti-48Al-2Cr-2Nb DLD process. In this paper, an innovative model was described, which combines a moving Gaussian distribution heat source and element birth and death technology in ANSYS, help to analysis cooling rate control method and guide crack-free deposits build process.
null
null
null
null
null
null
['Zhao, Xushan', 'Wang, Yuanxun', 'Wang, Guilan', 'Zhang, Haiou']
2021-11-18T17:35:16Z
2021-11-18T17:35:16Z
2019
Mechanical Engineering
null
['https://hdl.handle.net/2152/90440', 'http://dx.doi.org/10.26153/tsw/17361']
eng
2019 International Solid Freeform Fabrication Symposium
Open
['welding with rotation compression', 'WAAM', 'deformation control', 'residual stress']
Simulation of Hybrid WAAM and Rotation Compression Forming Process
Conference paper
https://repositories.lib.utexas.edu//bitstreams/4828c80a-3715-428e-ac0d-83d6d0e2f658/download
University of Texas at Austin
Wire arc additive manufacturing (WAAM) has been studied and widely applied due to its high forming efficiency and low production cost. In the process of WAAM, there are problems of cracking, deformation, large residual stress, insufficient properties, and instability caused by repeated rapid heating and chilling. Welding with rotation compression can control the performance and shape synchronously in the semi-solidified state of the weld pool. In this study, a new solution of hybrid WAAM and rotation compression is presented using follow-up rotating device to form the weld bead layer by layer. Base on the finite element analysis result of the hybrid process, the force energy curve of the rotation forming metal flowing process is obtained by arranging history monitory points and paths on the bead, and the relationship between the shape and forming load is revealed. The simulation model was verified by forming tests on middle carbon steel.
null
null
null
null
null
null
['Flach, Lawrance', 'Jacobs, Michelle A.', 'Klosterman, Donald A.', 'Chartoff, Richard P']
2019-02-25T17:27:10Z
2019-02-25T17:27:10Z
1998
Mechanical Engineering
null
['https://hdl.handle.net/2152/73475', 'http://dx.doi.org/10.26153/tsw/625']
eng
1998 International Solid Freeform Fabrication Symposium
Open
['LOM', 'lamination']
Simulation of Laminated Object Manufacturing (LOM) with Variation of Process Parameters
Conference paper
https://repositories.lib.utexas.edu//bitstreams/da50e362-709e-420c-b29d-d19a913ad486/download
null
A previously developed and verified thermal model for Laminated Object Manufacturing (LOM) was used to investigate the effects of various processing parameters on the temperature profile in a LOM part during the build cycle. The mathematical model, based on 3-dimensional transient heat conduction in a rectangular geometry LOM part, allows calculation ofthe transient temperature distribution within the part during the application of a new layer as well as during other periods ofthe LOM build cycle. The parameters roller temperature, roller speed, chamber air temperature, base plate temperature, and laser cutting time were independently varied, and the LOM process response simulated. The results were analyzed in order to gain insight into potential strategies for intelligent process control.
null
null
null
null
null
null
['Wang, Z.', 'Smith, D.E.']
2021-11-18T17:33:44Z
2021-11-18T17:33:44Z
2019
Mechanical Engineering
null
['https://hdl.handle.net/2152/90439', 'http://dx.doi.org/10.26153/tsw/17360']
eng
2019 International Solid Freeform Fabrication Symposium
Open
['melt flow', 'fiber orientation', 'numerical simulation', 'Galerkin Finite Element Method', 'polymer composites', 'polymer deposition additive manufacturing']
Simulation of Mutually Dependent Polymer Flow and Fiber Filled in Polymer Composite Deposition Additive Manufacturing
Conference paper
https://repositories.lib.utexas.edu//bitstreams/cdb68d7f-ab31-4c3b-b0fb-4581c5bd84b5/download
University of Texas at Austin
Short fiber-filled polymers experience increasing applications in melt extrusion additive manufacturing. As the filled polymer is melted and extruded, the fiber-filled polymer suspension exhibits mutually dependent effects, such that flow kinematics influence fiber orientation while the fiber alignment affects the formation of melt flow. This paper presents a fully-coupled numerical scheme to characterize the mutually dependent effects between melt flow and fiber orientation in a non-Newtonian axisymmetric extrusion flow including a free surface using the Galerkin Finite Element Method. The power law fluid model is employed to characterize the shear thinning rheological behaviors of polymer melts. This approach is used to solve the fully-coupled flow velocity and the fiber orientation fields for the nozzle extrusion flow in a large-scale polymer deposition additive manufacturing process. Computed results obtained from both the weakly-coupled and fully-coupled schemes exhibit notable differences in the flow velocity, fiber orientation tensor fields, die swell of free extrudate, and predicted elastic constants.
null
null
null
null
null
null
['Heller, B.P.', 'Smith, D.E.', 'Jack, D.A.']
2021-11-03T20:54:46Z
2021-11-03T20:54:46Z
2017
Mechanical Engineering
null
https://hdl.handle.net/2152/89931
eng
2017 International Solid Freeform Fabrication Symposium
Open
['polymer melt flow', 'melt flow', 'fiber orientation', 'planar deposition', 'finite element analysis', 'fused filament fabrication']
Simulation of Planar Deposition Polymer Melt Flow and Fiber Orientation in Fused Filament Fabrication
Conference paper
https://repositories.lib.utexas.edu//bitstreams/1fb0aa5c-a1a2-4b31-a0a0-901318a465ee/download
University of Texas at Austin
Mechanical and thermal properties of a 3D printed part are improved by adding discrete carbon fibers to the Fused Filament Fabrication (FFF) polymer feedstock. The properties of the fiber-filled composite are significantly influenced by the orientation of the carbon fibers within the extruded bead where fiber orientation in the bead is affected by the nozzle internal flow geometry, extrudate swell, and the deposition flow during the FFF process. In this work, a 2D Stokes flow finite element analysis is performed to evaluate FFF extrusion for a large-scale deposition extruder where special attention is given to the deposition of polymer melt on the moving platform below the nozzle. The shape of the extruded polymer is computed using a free surface normal velocity minimization technique. Once the velocity field and flow boundary is computed for the bead deposition process, fiber orientation and the resulting mechanical properties of the solidified composite are computed within the printed bead.
null
null
null
null
null
null
Brown, Stuart
2018-05-03T18:16:41Z
2018-05-03T18:16:41Z
1993
Mechanical Engineering
doi:10.15781/T2348H04J
http://hdl.handle.net/2152/65052
eng
1993 International Solid Freeform Fabrication Symposium
Open
['Department of Materials Science and Engineering', 'SFF', 'SFF geometry', '3D Printing']
Simulation of Solid Freeform Fabrication
Conference paper
https://repositories.lib.utexas.edu//bitstreams/e30cb355-63c1-47e0-84bd-9dd2c71ab0cd/download
null
Solid freeform fabrication involves highly coupled, nonlinear, thermomechanical processes. This investigation simulates the formation of a simple SFF geometry, a right, rectangular prism with aspect ratios of 1: 1:2. We include the effects of material variation, deposition path, and initial conditions to predict resulting distortion.
null
null
null
null
null
null
['Lee, Y.S.', 'Kirka, M.M.', 'Raghavan, N.', 'Dehoff, R.R.']
2021-11-03T20:29:47Z
2021-11-03T20:29:47Z
2017
Mechanical Engineering
null
https://hdl.handle.net/2152/89924
eng
2017 International Solid Freeform Fabrication Symposium
Open
['spot melting', 'scan strategy', 'solidification', 'columnar to equixaed transition', 'metal additive manufacturing']
Simulation of Spot Melting Scan Strategy to Predict Columnar to Equiaxed Transition in Metal Additive Manufacturing
Conference paper
https://repositories.lib.utexas.edu//bitstreams/14b633c5-5b49-4d2e-a7b2-259422adae6a/download
University of Texas at Austin
Recently, additive manufacturing (AM) processes are transforming from rapid prototyping technology to mass industrial production due to increase in the fidelity of the AM machines. This trend triggers the process optimization for various applications. In prior literature, high-fidelity numerical models have been presented to understand the rapid solidification conditions occurring during the process which includes heat transfer, fluid flow and beam interaction with the raw material. However, most of these models are simulating few melt passes and it is computationally expensive to simulate an entire layer of the component being fabricated. In this study, we use a low-fidelity model to simulate an entire layer. We also introduce a new melt strategy to control the solidification microstructure (i.e. columnar to equiaxed transition). The response of the solidification morphology to process parameters (ex. point offset, power, spot time) are investigated in terms of thermal gradient G and solidification rate R. The model is validated with the experimental microstructure data.
null
null
null
null
null
null
['Temur, R.', 'Coole, T.', 'Bocking, C.']
2019-10-18T16:35:13Z
2019-10-18T16:35:13Z
2001
Mechanical Engineering
null
['https://hdl.handle.net/2152/76254', 'http://dx.doi.org/10.26153/tsw/3343']
eng
2001 International Solid Freeform Fabrication Symposium
Open
Electrochemical
Simulation of the Electrochemical Machining Process
Conference paper
https://repositories.lib.utexas.edu//bitstreams/d94cde53-8b9d-4715-99db-6aeea1d0abed/download
null
Electrochemical machining (ECM) or erosion, is a process for shaping materials by means of the anodic dissolution of a work-piece using suitably shaped cathodes? However, the predictability of the process is poor due to current density variations over the electrode contour leading to poor dimensional tolerances. This paper describes how the process can be entirely simulated by computer. A model of the electric field during erosion is constructed based on the Laplace equations for the field. From the distribution of the electric field, it is possible to continuously calculate the current density at each point on the work-piece for the whole machining process. In this way, it is possible to predict the final work-piece contour by running the simulation program instead of the real process. Simulations for cylindrical, conical and spherical electrodes were carried out and compared to actual eroded parts.
null
null
null
null
null
null
['Weinhold, Benjamin', 'Heck, Blake', 'Albright, Ashton', 'Wang, Keran', 'Grote, Jon-Michael', 'Adeniji, Emmanuel', 'Masoomi, Mohammad', 'Thompson, Scott']
2021-12-01T21:44:03Z
2021-12-01T21:44:03Z
2021
Mechanical Engineering
null
['https://hdl.handle.net/2152/90623', 'http://dx.doi.org/10.26153/tsw/17542']
eng
2021 International Solid Freeform Fabrication Symposium
Open
['distortion', 'part-to-substrate location', 'build orientation', 'part quality', 'laser powder bed fusion']
Simulation of the Laser-Powder Bed Fusion Process for Determining the Effects of Part-to-Substrate Location and Orientation on Distortion in a Connecting Rod
Conference paper
https://repositories.lib.utexas.edu//bitstreams/628518cb-2d61-46d6-8033-4fe55077df19/download
University of Texas at Austin
The use of process simulation for designing parts and ensuring their effective additive manufacture can result in reduced product development times which would otherwise require costly trial-and-error manufacturing and testing experiments. The goal of this project was to determine the effects of part-to-substrate location and part build orientation on final part quality as measured via distortion. A connecting rod from an engine was selected for re-design for mass reduction and additive manufacturing via laser powder bed fusion (L-PBF). The rod was modeled and optimized using the topology optimization features of ANSYS® Workbench. A mass reduction of ~44% was achieved and unique design features were revealed. After topology optimization, the L-PBF process was simulated using the ANSYS Workbench Additive Wizard while having the optimized rod in three separate orientations at two different substrate locations. In all cases investigated, build orientation proved to have a more significant impact on distortion than substrate location. The effect of over supporting the part for distortion control can be investigated further to circumvent location/orientation dependencies.
null
null
null
null
null
null
['Seefried, M.', 'Zaeh, M.F.', 'Meindl, M.']
2020-02-13T21:04:52Z
2020-02-13T21:04:52Z
8/31/04
Mechanical Engineering
null
['https://hdl.handle.net/2152/79980', 'http://dx.doi.org/10.26153/tsw/7005']
eng
2004 International Solid Freeform Fabrication Symposium
Open
Indirect Metal Laser Sintering
Simulation of the Process Step Polymer Removal in Indirect Metal Laser Sintering
Conference paper
https://repositories.lib.utexas.edu//bitstreams/309d90f1-2abe-4387-9ba4-33a8c096d97a/download
null
With the Indirect Metal Laser Sintering and by means of a heat treatment in an oven process metal components can be produced. In the first step the polymer is transformed from the solid state into the gas phase. This takes place all over the component at different velocities depending on the local temperatures and temperature gradients. The creation of the gas phase develops a pressure inside of the component because the diffusion of the polymer within the part has a finite velocity. The pressure may contribute to a damage of the component. This essay deals with the procedure to simulate the gas pressure on the basis of the implementation of kinetic models in the Finite-Element-Analysis.
null
null
null
null
null
null
['Steinberger, J.', 'Shen, J.', 'Manetsberger, K.', 'Muellers, J.']
2019-09-23T16:40:36Z
2019-09-23T16:40:36Z
2000
Mechanical Engineering
null
['https://hdl.handle.net/2152/75962', 'http://dx.doi.org/10.26153/tsw/3061']
eng
2000 International Solid Freeform Fabrication Symposium
Open
Optimization
The Simulation of the SLS Process as the Basis of a Process Optimization 377
Conference paper
https://repositories.lib.utexas.edu//bitstreams/60f11499-1c84-47cb-8cb5-8b7195896451/download
null
In this work, a new model of the SLS process is introduced, offering the chance of analytically optimizing Selective Laser Sintering. The laser energy input is calculated by considering multiple scattering in the powder bed. The heat transfer is described by a new model which considers the heat flow through the growing sintering neck, and the sintering dynamics are determined by a new viscoelastic sintering model. All theoretical models are verified through experiments at near SLS conditions and are implemented in an enhanced FEM simulation of the process. Through this simulation, the major problems of the Selective Laser Sintering are illustrated and approaches for optimization of the SLS process are shown.
null
null
null
null
null
null
['Delfs, Patrick', 'Herale, Ashrith Ananthraj', 'Li, Zhiyuan', 'Schmid, Hans-Joachim']
2021-10-18T22:32:25Z
2021-10-18T22:32:25Z
2014
Mechanical Engineering
null
https://hdl.handle.net/2152/89273
eng
2014 International Solid Freeform Fabrication Symposium
Open
['laser sintering', 'surface roughness', 'surface topography']
Simulation of the Surface Topography on Laser Sintered Polymer Parts
Conference paper
https://repositories.lib.utexas.edu//bitstreams/fccddedd-470c-48fc-976e-6af6a81cbb71/download
University of Texas at Austin
One barrier of laser sintering (LS) to become the main process for Direct Manufacturing (DM) is the surface quality of LS parts. Hence, the property which has to be improved is the rough surfaces of LS parts due to the layered structure. Another additional effect is the incomplete melting of powder particles on the surface due to the high process temperature. In this paper we demonstrate our approach of a theoretical model for the topography of LS part surfaces. We investigated the surface roughness as a function of surface orientation. Considering that the model involves further variables as layer thickness, particle density and particle size distribution to describe the topography precisely. Experimental results were used to optimize and check the results of the model.
null
null
null
null
null
null
['Zhang, Kai', 'Liu, Tingting', 'Liao, Wenhe', 'Zhang, Changdong', 'Zheng, Yi', 'Shao, Huang']
2021-11-15T20:39:52Z
2021-11-15T20:39:52Z
2018
Mechanical Engineering
null
['https://hdl.handle.net/2152/90263', 'http://dx.doi.org/10.26153/tsw/17184']
eng
2018 International Solid Freeform Fabrication Symposium
Open
['thermal behavior', 'molten pool', 'solidification', 'selective laser melting', 'alumina']
Simulation of the Thermal Behavior and Analysis of Solidification Process During Selective Laser Melting of Alumina
Conference paper
https://repositories.lib.utexas.edu//bitstreams/2f44e69e-f889-43b4-8c60-d4b7fad92c73/download
University of Texas at Austin
Selective laser melting (SLM) has rapidly developed in the past decade. High precision-complex ceramics parts can be directly fabricated using this technology. To study the thermal behavior of molten pools in the selective laser melting of alumina (Al2O3), we established a three-dimensional model based on ANSYS. Then, combined with simulation results, the physical phenomena during the rapid solidification process were discussed. The simulation results showed that the laser power and scanning speed exerts a marked influence on the maximum temperature, liquid lifetime, dimensions, and temperature gradient of the molten pool. Owing to the different temperature gradients in the molten pool, the thermal capillary force on the free surface varies. As a result, a slight difference exists between the stripy solidification structures. Different orientations of columnar crystals can be obtained. The underlying mechanism controls the direction of the temperature gradient with suitable processing routes, such as decreasing the scanning speed.
null
null
null
null
null
null
['Gartner, P.', 'Krischke, N.', 'Benfer, M.', 'Bender, M.', 'Lanza, G.', 'Fleischer, J.', 'Dost, G.']
2023-04-05T13:58:09Z
2023-04-05T13:58:09Z
2022
Mechanical Engineering
null
['https://hdl.handle.net/2152/117777', 'http://dx.doi.org/10.26153/tsw/44656']
eng
2022 International Solid Freeform Fabrication Symposium
Open
AM parts
Single Part Tracking Enabled by Fluorescent Polysecure Tracing Particles in Am Parts
Conference paper
https://repositories.lib.utexas.edu//bitstreams/b1e6dbf5-1de1-41f8-9fff-0615b2084400/download
null
Traceability is widely recognized as a core enabler of many industry 4.0 technologies. The necessary identification of products is often realized through label-based systems, but tracing products with particular geometric constraints that prohibit the use of such systems remains an issue. A promising alternative of label based identification is the pattern based identification. This contribution portrays a novel method to utilize fluorescent particles integrated in polymer-based products and optical pattern recognition to facilitate the identification of products with specific geometric constraints. The particles are integrated into the polymer and the unique random distribution of fluorescent particles triggered by an LED flash is used to recognize individual products. To demonstrate the approach, polymer-based gear wheels were printed using ARBURG plastic freeforming and an automatic identification system was designed. The presented approach could be a reliable alternative to other surface-structure-based approaches for product identification and enable comprehensive tracing of components throughout value-chains.
null
null
null
null
null
null
['Borish, Michael', 'Roschli, Alex', 'Wade, Charles', 'Post, Brian', 'White, Liam', 'Adkins, Cameron']
2024-03-26T20:16:54Z
2024-03-26T20:16:54Z
2023
Mechanical Engineering
null
['https://hdl.handle.net/2152/124391', 'https://doi.org/10.26153/tsw/50999']
en_US
2023 International Solid Freeform Fabrication Symposium
Open
['slicing', 'manufacturing', 'spiralization', 'continuous fiber deposition', 'single path', 'graph theory', 'topological hierarchy']
Single Path Generation for Closed Contours via Graph Theory and Topological Hierarchy
Conference paper
https://repositories.lib.utexas.edu//bitstreams/532730f7-7bb8-4098-8f07-18b7bef1e79a/download
University of Texas at Austin
Slicing converts a 3D object into a set of 2D polygons that are filled with multiple path types. These paths involve travels where the extruder of the machine must stop building, lift, travel to the next path, lower, and resume construction. Travels are considered wasted time as construction of the object is not occurring. Further, the start/stop point, called a seam, causes both reduced aesthetic and weaker material properties. To address these issues, an algorithmic approach was developed to compute a continuous single path from closed contours. The algorithm utilizes graph theory and a topological hierarchy to produce a single path for an individual layer. This approach can be combined with spiralization techniques to compute a single path for entire objects. The resulting objects can be constructed quicker and have improved material properties as verified via tensile testing.
null
null
null
null
null
null
['Gong, Haijun', 'Teng, Chong', 'Zeng, Kai', 'Pal, Deepankar', 'Stucker, Brent', 'Dilip, J.J.S.', 'Beuth, Jack', 'Lewandowski, J.']
2021-10-28T21:05:11Z
2021-10-28T21:05:11Z
2016
Mechanical Engineering
null
https://hdl.handle.net/2152/89700
eng
2016 International Solid Freeform Fabrication Symposium
Open
['single track', 'support structure', 'powder bed', 'Ti-6Al-4V', 'selective laser melting']
Single Track of Selective Laser Melting Ti-6Al-4V Powder on Support Structure
Conference paper
https://repositories.lib.utexas.edu//bitstreams/8c3eb163-6248-43b7-ae34-097f3eff0983/download
University of Texas at Austin
Melt pool shows inconsistency due to the varied heat conditions in selective laser melting (SLM) process, even if identical process parameters are used. The characterization of the actual melt pool shape is highly desired in order to eventually control the quality and property of additive manufacturing products. It has been well understood that base plate provides high thermal conduction while powder bed is low thermal condition for fusion energy to be dissipated. Based on former study of melt pool characterization on a base plate, this study creates single tracks on the support structure, which is considered the similar heat condition of the Ti-6Al-4V powder bed. Various patterns of the support structure are fabricated for single track deposition, in order to investigate the effect of the support structure on melt pool consistency and continuity. Different laser melting parameters are used in the experiments to understand their effects on the melt pool morphology.
null
null
null
null
null
null
['Ramos, Jorge A.', 'Murphy, Jeremy', 'Lappo, Karmen', 'Wood, Kristin', 'Bourell, David L.', 'Beaman, Joseph J.']
2019-10-23T14:40:08Z
2019-10-23T14:40:08Z
2002
Mechanical Engineering
null
['https://hdl.handle.net/2152/76749', 'http://dx.doi.org/10.26153/tsw/3838']
eng
2002 International Solid Freeform Fabrication Symposium
Open
Superalloy
Single-Layer Deposits of Nickel Base Superalloy by Means of Selective Laser Sintering
Conference paper
https://repositories.lib.utexas.edu//bitstreams/04a1c55c-eeaf-4df0-a564-50099e7d0586/download
null
Single layer deposits consisting of Mar-M 247 powder were consolidated on Alloy 718 polycrystalline flat sheets by means of the Selective Laser Melting (SLM) technique. The deposition process consisted in selectively fusing a powder bed precompacted using of an insulating non-wettable mask trough. The mask-powder-substrate arrangement was pre-heated inside a processing chamber under high vacuum. An inertreducing atmosphere was applied, and a focused Nd:YAG laser beam was then raster scanned at high speed along the contour of the trough, providing energy to induce a melting front to propagate along the powder as well as over the surface of the plate. As the laser beam moved forward a solidification front was left behind with a metallurgical bond between the substrate and the deposited layer. Optical microscopy revealed that epitaxial growth occurred in the [001] direction from the melted substrate to about half the height of the deposits. Above that height, the [001] dendritic front bowed towards the [100] direction. A dendritic-equiaxed transition appeared near the free surface of the deposit. These results indicate that the SLM technique could have potential application for growing single crystal structures as well as in repairing damaged or worn turbine blades.
Funding for this project was provided by Rolls-Royce North America and the University of Texas at Austin.
null
null
null
null
null
['Nelson, Christian', 'Barlow, J.W.']
2018-04-12T17:20:57Z
2018-04-12T17:20:57Z
1990
Mechanical Engineering
doi:10.15781/T2GM8256M
http://hdl.handle.net/2152/64269
eng
1990 International Solid Freeform Fabrication Symposium
Open
['Department of Chemical Engineering', 'Selective laser sintering', 'SLS machine']
Sintering Rates in the Selective Laser Sintering Process
Conference paper
https://repositories.lib.utexas.edu//bitstreams/345d3ebb-fc9b-4c4a-8814-9043bf8b58f4/download
null
This paper presents. a procedure to determine rates of sintering as a function of temperature using an isothermaloven. The rate of height change of a powder sample in the oven at temperatures near the Tg or Tm is measured. From this information an activation energy is calculated. This activation energy is similar to activation energies calculated from viscosity versus ternp.erature curves for polymer melts. This similarity suggests that viscous sint~ring models such. as those by Frenkel and Scherer are appropriate. A comparison between sintering rates of polymer coated alumina powder and mixed powders of the polymer with alumina, suggest that better sintered products may result from the coated powders than from simple mixtures.
null
null
null
null
null
null
['Khoshnevis, Behrokh', 'Asiabanpour, Bahram', 'Mojdeh, Mehdi', 'Koraishy, Babar', 'Palmer, Kurt', 'Deng, Zongliang']
2019-10-24T18:17:50Z
2019-10-24T18:17:50Z
2002
Mechanical Engineering
null
['https://hdl.handle.net/2152/77416', 'http://dx.doi.org/10.26153/tsw/4505']
eng
2002 International Solid Freeform Fabrication Symposium
Open
Powder Sintering
SIS-A New SFF Method Based on Powder Sintering
Conference paper
https://repositories.lib.utexas.edu//bitstreams/fc60b55b-d7e2-4a38-9493-866d022f4f96/download
null
Selective Inhibition of Sintering is a layered fabrication process which is capable of rapidly producing accurate functional parts out of polymers and metals using a relatively inexpensive machine. This article presents a brief overview of the research and development aimed at establishing the feasibility and the potential of the process.
This material is based upon work supported by the National Science Foundation under SGER Grant No. 0088135, and Long Range Scientific and Technology Program of Office of Naval Research.
null
null
null
null
null
['Wu, Yan', 'Yang, Li']
2021-11-09T20:33:01Z
2021-11-09T20:33:01Z
2018
Mechanical Engineering
null
['https://hdl.handle.net/2152/90159', 'http://dx.doi.org/10.26153/tsw/17080']
eng
2018 International Solid Freeform Fabrication Symposium
Open
['fracture behavior', 'cellular structures', 'size', 'topology effects', 'bending', 'stretching']
Size and Topology Effects on Fracture Behavior of Cellular Structures
Conference paper
https://repositories.lib.utexas.edu//bitstreams/3addc476-8837-45fe-8b24-6d92f7261ce5/download
University of Texas at Austin
Cellular structures can deform by either the bending, stretching or both of the cell walls or cell struts. In this study, the fracture characteristics of multiple typical cellular structures that represent both the bending-dominated and stretching-dominated structures were investigated. An analytical model based on the matrix displacement method was established for the analysis of the fracture progression of the cellular structures, which was consequently employed for the fracture analysis of the cellular structures under various geometry design conditions including cell topology, cell size and number of unit cells. From the results, it was shown that the fracture propagation patterns and stress characteristics of the two cellular designs (diamond and triangular) exhibit different dependencies on their geometry designs and cellular patterns. While the stretch-dominated triangular structure exhibit higher fracture strength compared to the bending-dominated diamond structure, it also exhibits more rapid fracture propagation and more significant size effect.
null
null
null
null
null
null
['Eiamsa-ard, Kunnayut', 'Zhang, Jun', 'Liou, F.W.']
2019-09-26T17:27:00Z
2019-09-26T17:27:00Z
2001
Mechanical Engineering
null
['https://hdl.handle.net/2152/76026', 'http://dx.doi.org/10.26153/tsw/3125']
eng
2001 International Solid Freeform Fabrication Symposium
Open
Manufacturing
Skeleton-based Geometric Reasoning for Adaptive Slicing in a Five-axis Laser Aided Manufacturing Process System
Conference paper
https://repositories.lib.utexas.edu//bitstreams/e638211b-26b4-4257-92c8-e7adc08f7374/download
null
Multi-axis Laser Aided Manufacturing Process (LAMP) is an additive manufacturing process similar to laser cladding. This process can produce full functional parts [1]. Traditional Layered Manufacturing processes produce parts with limited surface quality; and also the build time is often long due to the deposition of sacrificial support structure. The multiple degrees of freedom endow the LAMP system a capability to build parts without support structure. An algorithm for adaptive slicing based on skeleton is presented in this paper. The skeleton is useful for many applications such as feature recognition, robot path planning, shape analysis, and etc [2]. The near optimal build direction can be generated using information provided by the part skeleton, which is a 2D (or less) “surfaces” embedded 3D space containing the general form of the object.
null
null
null
null
null
null
['Chesser, Phillip', 'Post, Brian', 'Lind, Randy', 'Roschli, Alex', 'Atkins, Celeste', 'Boulger, Alex', 'Mhatre, Paritosh', 'Lloyd, Pete']
2021-11-18T18:32:51Z
2021-11-18T18:32:51Z
2019
Mechanical Engineering
null
['https://hdl.handle.net/2152/90459', 'http://dx.doi.org/10.26153/tsw/17380']
eng
2019 International Solid Freeform Fabrication Symposium
Open
['SkyBAAM', 'large-scale fieldable deposition system', 'concrete deposition system', 'Oak Ridge National Laboratory']
SkyBAAM Large-Scale Fieldable Deposition Platform System Architecture
Conference paper
https://repositories.lib.utexas.edu//bitstreams/83844e5d-8f3a-40ed-9567-ec1f7d89aedb/download
University of Texas at Austin
Oak Ridge National Laboratory (ORNL) is currently developing a concrete deposition system for infrastructure-scale printed objects. This system, called SkyBAAM, uses a cable driven motion platform to manipulate the print head. This work focuses on the general aspects of the system architecture, including arrangement of the cable driven platform, general high-level control methodology, and system accuracy, along with concrete deposition methods. Results and demonstration prints will be shown.
null
null
null
null
null
null
['Pang, Thomas', 'Figueroa, Israel', 'Fong, John', 'Melisaris, Anastasios', 'Wang, Renyi', 'Hanna, Stephen', 'Nguyen, Hop', 'Guertin, Michelle', 'Phan, Cathy']
2018-12-05T17:27:29Z
2018-12-05T17:27:29Z
1997
Mechanical Engineering
doi:10.15781/T2P844G4D
http://hdl.handle.net/2152/71401
eng
1997 International Solid Freeform Fabrication Symposium
Open
['SFF', 'SLA technology']
SL 5410: High Humidity, Water, and Heat Resistant Resin for Stereolithography
Conference paper
https://repositories.lib.utexas.edu//bitstreams/c6cd7884-df3e-4c94-af19-451be3f2eeeb/download
null
A new Stereolithography (SL) resin, CibaTool® SL 5410, which imparts good humidity and heat resistance, was released in July, 1997. This epoxy based resin for SLA-500 was developed mainly to eliminate the relatively weak resistance to high humidity and high heat that the first generation ofresins suffered from. Namely, with this new resin, strength ofQuickCast part and solid parts can now be maintained under high relative humidity. Even when immersed into water, part strength of SL 5410 is essentially preserved. Thermomechanical properties have also improved significantly relative to those of SL 5180. Heat deflection temperature and Tg values increased by +15°C to +40°C, to as high as 88°C and 105°C, respectively, for SL 5410, when parts were additionally thermally postcured. Improvements in mechanical properties are also included in this paper. These property enhancements were achieved while further improving part accuracy, vertical surface finish, and productivity. Productivity may increase by as much as 2.5-fold over SL 5180. Also, SL 5410 requires no predip delay, hence cutting the overhead time. These newly achieved resin characteristics for SL 5410 are expected to improve the ease-of-use in today's applications, and open new fields of applications in the near future.
null
null
null
null
null
null
['McPherson, Jace', 'Bliss, Adam', 'Smith, Flora', 'Hariss, Edmund', 'Zhou, Wenchao']
2021-11-02T20:24:01Z
2021-11-02T20:24:01Z
2017
Mechanical Engineering
null
https://hdl.handle.net/2152/89887
eng
2017 International Solid Freeform Fabrication Symposium
Open
['slicer', 'mobile printer', 'cooperative 3D printing', 'fused deposition modeling']
A Slicer and Simulator for Cooperative 3D Printing
Conference paper
https://repositories.lib.utexas.edu//bitstreams/12030264-9fd0-4f80-9c54-d293a7b9d41d/download
University of Texas at Austin
Cooperative 3D printing is an emerging technology that aims to increase the 3D printing speed and to overcome the size limit of the printable object by having multiple mobile 3D printers (or printhead-carrying mobile robots) work together on a single print job on a factory floor. It differs from traditional layer-by-layer 3D printing due to the requirement for multiple mobile printers working simultaneously without interfering with each other. Therefore, a new approach for slicing the CAD model and generating commands for the mobile printers is needed, which has not been discussed in the literature before. We propose a chunk-by-chunk based slicer that divides an object into chunks so that different mobile printers can print different chunks simultaneously without interfering with each other. In this paper, we developed a slicer for cooperative 3D printing with two mobile fused deposition modeling (FDM) printers. In order to validate our slicer and visualize the cooperative 3D printing process, we have also developed a simulator environment, which can be a valuable tool in optimizing cooperative 3D printing strategy. Results show that the developed slicer and simulator are working effectively.
null
null
null
null
null
null
['Sundaram, R.', 'Choi, J.']
2019-10-18T16:02:13Z
2019-10-18T16:02:13Z
2001
Mechanical Engineering
null
['https://hdl.handle.net/2152/76245', 'http://dx.doi.org/10.26153/tsw/3334']
eng
2001 International Solid Freeform Fabrication Symposium
Open
5-Axis
A Slicing Procedure for 5-Axis layered Manufacturing
Conference paper
https://repositories.lib.utexas.edu//bitstreams/49e382be-21a3-4302-8ed0-e199448232cf/download
null
The 5-axis layered manufacturing technology facilitates fabrication of a part with overhanging features without the use of supports, thereby making a direct-to-use part from the layered manufacturing technology a reality. In this paper we describe a direct slicing procedure for a CAD model, a crucial process planning task for the 5-axis layered manufacturing. The neutral exchange format IGES is used as the slice format. The G and M codes for a CNC 5-axis laser deposition machine are generated from the slice format and the deposition process is simulated. Implemented examples are included to explain the slicing procedure. Exciting possibilities for the future work on the slicing procedure are discussed.
null
null
null
null
null
null
['Haeseong, J. Jee', 'Lee, Byong-Yeol']
2019-03-12T16:15:30Z
2019-03-12T16:15:30Z
1999
Mechanical Engineering
null
['https://hdl.handle.net/2152/73595', 'http://dx.doi.org/10.26153/tsw/737']
eng
1999 International Solid Freeform Fabrication Symposium
Open
['SFF', 'CAD']
Slicing STEP-based CAD Models for CAD/RP Interface
Conference paper
https://repositories.lib.utexas.edu//bitstreams/a0586a06-7c8b-48f7-a258-782369df17b9/download
null
SFF technologies have an ability of creating a physical part directly .•. from its computer model by. adding material on a layer by layer basis. One of the problems lies in their current file fonnat for CAD data exchange. Current method using the de facto industry standard STL have at times resulted in problems such< as accuracy, redundancy, and integrity in its representing CAD models. In this paper we propose a method of slicing and editing STEP...based. RP models for the new data transfer paradigm between CAD systems and RPsystems using STEP
null
null
null
null
null
null
['Ainsley, C.', 'Hon, K.K.B.']
2018-11-09T16:40:53Z
2018-11-09T16:40:53Z
1996
Mechanical Engineering
doi:10.15781/T2JH3DN57
http://hdl.handle.net/2152/69934
eng
1996 International Solid Freeform Fabrication Symposium
Open
['free form fabrication', 'ceramic industry', 'casting']
Slip Casting as a Rapid Tooling Process
Conference paper
https://repositories.lib.utexas.edu//bitstreams/f1be120a-cb2a-43b8-b8c1-3c3589da54ee/download
null
The paper discusses the slip casting ofstainless steel as a method offorming injection moulding tooling. Main steps involved in the precision slip casting ofstainless steel and the effects ofmajor parameters such as casting rate have on accuracy are fully discussed. The slip casting process has numerous technical advantages over conventional and rapid tooling processes especially there is strong potential for producing mass production tooling.
null
null
null
null
null
null
['Hagedorn, Y.-C.', 'Balachandran, N.', 'Meiners, W.', 'Wissenbach, K.', 'Poprawe, R.']
2021-10-05T14:19:35Z
2021-10-05T14:19:35Z
8/17/11
Mechanical Engineering
null
['https://hdl.handle.net/2152/88376', 'http://dx.doi.org/10.26153/tsw/15315']
eng
2011 International Solid Freeform Fabrication Symposium
Open
['Additive Manufacturing', 'Selective Laser Melting', 'ceramics', 'dental restorations']
SLM of Net-Shaped High Strength Ceramics: New Opportunities for Producing Dental Restorations
Conference paper
https://repositories.lib.utexas.edu//bitstreams/0ddef393-a609-4565-971d-34905b818c06/download
University of Texas at Austin
Oxide ceramics yield excellent mechanical properties along with outstanding thermal and wear resistance. However, little work on additive Manufacturing (AM) of high-strength ceramics has been stated. In the present paper the current state of development in Selective Laser Melting (SLM) of pure ceramic specimens is reviewed. During the present approach the eutectic mixture of pure alumina (Ah0 3) and zirconia (Zr02) powder is completely molten while crack formation is prevented by a high-temperature C02-Iaser preheating. This approach yields net-shaped, fully dense specimens reaching flexural strengths of above 500 MPa without post-processing. One potential application for this technology are fully-ceramic dental restorations frameworks, as the demanded maximum loads of above I 000 N are met. Alternative preheating strategies are presented to allow for manufacturing larger volumetric parts.
null
null
null
null
null
null
['Haberer, Marc', 'Zak, Gennady', 'Park, Chul', 'Paraschivoiu, Marius', 'Benhabib, Beno']
2019-09-23T16:29:25Z
2019-09-23T16:29:25Z
2000
Mechanical Engineering
null
['https://hdl.handle.net/2152/75956', 'http://dx.doi.org/10.26153/tsw/3055']
eng
2000 International Solid Freeform Fabrication Symposium
Open
Ribre-Reinforced
Slot-Coating for Rapid Manufacturing of Fibre-Reinforced Parts 333
Conference paper
https://repositories.lib.utexas.edu//bitstreams/85e3e941-a805-46f8-a093-db010808a6c9/download
null
Mechanical properties of parts manufactured through photolithography process are improved through the addition of short glass fibres. A lithography-based prototyping system for the manufacture of such composite parts has been under development in our laboratory. This paper will specifically detail a novel Liquid Layer Formation Subsystem (LLFS) for the creation of thin layers of glass-fibres/photopolymer mixture for this system. New LLFS combines a unique external mixing subsystem with a precisely controlled slot coater in order to deposit layers of uniform fibre volume fraction throughout the fabrication process. Evaluation of the mixing subsystem found it capable of delivering liquid with the expected fibre content, and examination of the geometric quality of the individual layers formed by the LLDS shows its ability to consistently build layers of correct height.
null
null
null
null
null
null
Boivie, Klas
2019-09-23T15:16:02Z
2019-09-23T15:16:02Z
2000
Mechanical Engineering
null
['https://hdl.handle.net/2152/75932', 'http://dx.doi.org/10.26153/tsw/3031']
eng
2000 International Solid Freeform Fabrication Symposium
Open
Sintering
SLS Application of the Fe-Cu-C System for Liquid Phase Sintering 141
Conference paper
https://repositories.lib.utexas.edu//bitstreams/d161fe81-14ea-4fca-be7b-7f958da09ad6/download
null
The present work suggests the possibility to exploit the phenomena of copper swelling, and the controlling effect of carbon during liquid phase sintering, to be used in SLS technology to achieve temperable tooling materials in a single furnace cycle. As a basic investigation of this possibility, four powder samples of different copper and carbon content were tried and evaluated in respect to SLS and furnace behavior. The possibility to form green bodies was verified and the different sintering behaviors were studied. It was concluded that this material system holds several interesting phenomena that, if properly managed and if sufficient fractional packing density could be reached, could open distinct possibilities to achieve high quality material for SLS tooling purposes.
null
null
null
null
null
null
['Kim, J.H.', 'Creasy, T.S.']
2019-10-23T14:42:49Z
2019-10-23T14:42:49Z
2002
Mechanical Engineering
null
['https://hdl.handle.net/2152/76750', 'http://dx.doi.org/10.26153/tsw/3839']
eng
2002 International Solid Freeform Fabrication Symposium
Open
Nanoparticle
The SLS Characteristics of 1.8wt% Clay Nanoparticle/Nylon 6 Composite
Conference paper
https://repositories.lib.utexas.edu//bitstreams/e0fdc923-6400-460b-87d4-7857dbbcbe6e/download
null
Selective laser sintering (SLS) characteristics of clay nanoparticle/Nylon 6 composite were studied for the applications in Rapid Prototyping and Manufacturing (RP&M). Differences of sintering behaviors between the nanocomposite and standard SLS polymers were investigated. Nanoparticles change the material’s properties and this requires, modification of SLS processing parameters. An attritor ground the as-received pellets into 100µm-sized particles. The nanocomposite's sintering behavior showed higher porosity compare with standard polymers.
null
null
null
null
null
null
['Niino, Toshiki', 'Sakai, Yasuyuki', 'Huang, Hongyun', 'Naruke, Hiromichi']
2020-02-27T20:58:25Z
2020-02-27T20:58:25Z
9/14/06
Mechanical Engineering
null
['https://hdl.handle.net/2152/80106', 'http://dx.doi.org/10.26153/tsw/7127']
eng
2006 International Solid Freeform Fabrication Symposium
Open
Polycaprolactone powder
SLS Fabrication of Highly Porous Model Including Fine Flow Channel Network Aiming at Regeneration of Highly Metabolic Organs
Conference paper
https://repositories.lib.utexas.edu//bitstreams/f8a8f554-6364-4222-80b8-06b93ee65865/download
null
Fabrication of very porous scaffold for regeneration of highly metabolic organs is reported. Polycaprolactone (PCL) powder was mixed with fine salt grains as filler and SLS processed to develop a model including fine flow channel network. The fabricated model was rinsed with water to dissolve the salt, and high porosity of 90% was successfully obtained. Additionally, residual powder in the channels was effectively removed by solution of the filler. Through micro-CT observation, it was confirmed that channels of which diameter was smaller than 1mm were successfully fabricated and repeating branching and merging. Result of culture test is also reported.
null
null
null
null
null
null
['Evans, R. S.', 'Bourell, D. L.', 'Beaman, J. J.', 'Campbell, M. I.']
2020-02-20T21:11:09Z
2020-02-20T21:11:09Z
2005
Mechanical Engineering
null
https://hdl.handle.net/2152/80056
eng
2005 International Solid Freeform Fabrication Symposium
Open
Rapid prototyping
SLS Materials Development Method for Rapid Manufacturing
Conference paper
https://repositories.lib.utexas.edu//bitstreams/8762714a-6d67-4e78-860b-852853597713/download
null
As soon as SFF technology development began to make Rapid Prototyping possible the interest in Rapid Manufacturing (RM) began to grow. The advantages in terms of functional integration, elimination of tooling and fixtures and mass customization make a compelling case for RM, leading some in the field to call it the next industrial revolution. Yet without the materials properties necessary to provide the function and variety currently available from mass production methods, the application of RM will remain limited. Developing new materials for the SLS process, one immediate step toward a larger portfolio of RM materials, is very challenging. The formation of high quality SLS parts relies on appropriate powder characteristics, thermal cycles and sintering behavior. Based on a brief examination of the key factors in SLS processing and a research project to develop a new binder material for Silicon Carbide composites, a systematic materials development method is proposed in this paper. The method provides guidance for introducing new SLS materials, support for educating new SLS users and researchers and direction for several future research projects.
null
null
null
null
null
null