ccm/sff-papers · Datasets at Hugging Face

['Gill, David', 'Smugeresky, John', 'Atwood, Clinton J.']

2020-03-05T20:26:43Z

2006

English

null

['https://hdl.handle.net/2152/80160', 'http://dx.doi.org/10.26153/tsw/7181']

eng

2006 International Solid Freeform Fabrication Symposium

Open

Laser Engineered Net Shaping

Repeatability Analysis of 304L Deposition by the LENS® Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d6762abc-ae3c-4af9-a403-f41bbb46c222/download

null

Sandia National Laboratories is currently engaging in an effort to qualify Laser Engineered Net Shaping™ (LENS®) as a repair and modification process for high rigor metal components. As part of that effort, the LENS team has conducted a process repeatability test to help identify variation within the system. This test utilized 304L stainless steel which is a commonly used material at Sandia. Over the course of 12 weeks, 3/8”x3/8”x2” towers were built in sets of 3 with a total of 30 towers completed. A random sampling of 10 of these towers (1 from each set of 3) had been identified before depositing the towers, and these towers were used for tensile testing and metallographic testing. The testing showed the ultimate and yield strengths of all samples to be well above those of annealed 304L. This is expected because of the rapid melt pool solidification present in the LENS process and the resulting grain refinement. The ductility, which usually remains on par with annealed 304L, was found to be lower. The final cause of this loss of ductility was determined to be inter-layer separation due to loose wires in the closed loop melt pool control system.

null

['Whiting, Justin G.', 'Tondare, Vipin N.', 'Moylan, Shawn P.']

2023-01-26T14:20:27Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117304', 'http://dx.doi.org/10.26153/tsw/44185']

eng

2022 International Solid Freeform Fabrication Symposium

Open

Additive manufacturing

Repeatability and Sensitivity of a Rotating Drum Method for Rheological Characterization of Stainless Steel Powders Used for Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/878ffeb1-8756-4c45-ad19-2f21f0001d3a/download

null

There remains a need for rheological characterization of metal powder used for powder- spreading-based additive manufacturing (AM). Novel powder rheometers introduced to the commercial market for this purpose must be rigorously evaluated for repeatability and sensitivity before widespread adoption for predicting AM powder performance. The work presented here focuses on the quantification of the repeatability and sensitivity of a commercially available rotating drum powder rheometer for testing metal AM powder. This assessment is accomplished via a set of tests that include the following independent variables: cleaning method, the mass of the sample, particle size distribution, material, and hysteresis.

null

['Kumar, Ashok V.', 'Wood, Aaron']

2019-03-12T16:19:26Z

1999

Mechanical Engineering

null

['https://hdl.handle.net/2152/73596', 'http://dx.doi.org/10.26153/tsw/738']

eng

1999 International Solid Freeform Fabrication Symposium

Open

['SFF', 'SLS']

Representation and design of heterogeneous components

Conference paper

https://repositories.lib.utexas.edu//bitstreams/819064dc-0e6f-4a2b-9032-23b4c5dc4dee/download

null

Recent advances in rapid prototyping techniques enable the fabrication of components whose composition can be controlled and varied in any desired fashion. This presents design engineers with the opportunity and the challenge to design heterogeneous components that optimize some design objective or can. provide certain functionality. However, there are no well-established techniques for representing heterogeneous components or design tools to arrive at the appropriate col11positiondistribution. A shape and composition model based on iso-parametric interpolation functions.is. presented that can be used in conjunction with non-linear programming algorithms to automatically compute optimal composition distribution.

null

['Alonso, Matthew Paul', 'Malone, Evan', 'Moon, Francis C.', 'Lipson, Hod']

2021-09-29T20:08:11Z

2009-09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88208', 'http://dx.doi.org/10.26153/tsw/15149']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['telegraph', 'solid freeform fabrication', 'electromagnet', 'electromechanical', 'deposition', 'rapid prototyping', 'magnetic', 'assembly']

Reprinting the Telegraph: Replicating the Vail Register using Multi-Materials 3D Printing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8685fe8a-d5f2-4f6a-bf15-0ef9ed9747ca/download

University of Texas at Austin

Solid Freeform Fabrication is a family of manufacturing processes that create three-dimensional objects by depositing material, layer-by-layer. Traditionally, this technology has been used to fabricate passive parts, but recently it has been used for producing active components such as batteries and soft-polymer actuators. In this paper we demonstrate the ability of this process to fabricate a complete, active electromechanical system. Using only SFF processes, we reproduced the 1844 Vail register - a landmark in digital communications history. With the techniques developed in this research, a range of solenoid devices can be fabricated and embedded into freeform fabricated devices. This could enable the realization of novel and otherwise difficult to manufacture electromechanical designs.

null

['Liou, F.W.', 'Choi, J.', 'Landers, R.G.', 'Janardhan, V.', 'Balakrishnan, S.N.', 'Agarwal, S.']

2019-10-09T16:27:40Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76157', 'http://dx.doi.org/10.26153/tsw/3246']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Hybrid

Research and Development of a Hybrid Rapid Manufacturing Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ce4c0026-dcc9-4064-a4bf-8ff28a7f5832/download

null

This paper presents the research and development of a hybrid rapid manufacturing process being developed at the University of Missouri-Rolla. This process includes a laser deposition and a 5- axis CNC milling system. By combining laser deposition and machining processes, the resulting hybrid process can provide greater build capability and better accuracy and surface finish. The hybrid process can build some features that are difficult to build in using a purely deposition processes. The issues and related approaches in the research and development of the hybrid deposition-machining process, including laser deposition process, system design and integration, process planning, and sensor selection and control, are discussed.

This research was supported by the National Science Foundation Grant Number DMI9871185, Missouri Research Board, and a grant from the Missouri Department of Economic Development through the MRTC grant.

null

['Fahad, M.', 'Gilbert, M.', 'Dickens, P.']

2021-09-30T13:30:17Z

9/23/10

Mechanical Engineering

null

['https://hdl.handle.net/2152/88237', 'http://dx.doi.org/10.26153/tsw/15178']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['support material', 'jetting', 'caprolactam', 'pluronic F-127', 'Rapid Manufacturing', 'Fourier Transform Infrared Spectroscopy', 'Polarization Microscopy']

Research into a Novel Support Material for Jetting Based RM Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/32dcf99c-9e54-4790-a64a-5d3947d1e6b7/download

University of Texas at Austin

Jetting of caprolactam is a new Rapid Manufacturing process currently in the early phases of research at Loughborough University. Support material is required to successfully build a part using this method. This work is therefore, aimed at finding a suitable support material for jetting of caprolactam. Pluronic F-127 with a non aqueous solvent was investigated using different experimental techniques such as heating and cooling between 25 to 1500C, Fourier Transform Infrared Spectroscopy and Polarization Microscopy and the possibility of use of these systems as a support material is discussed. The results suggested that when Pluronic F-127 in ethylene glycol is heated, it does not form a gel at concentrations lower than 25% (w/w) whereas at 25%, a gel state was observed near 500C. All concentrations studied formed a white wax like solid upon cooling due to a changed conformational structure of PEO chains. Although, a gel/solid state was not observed at high temperatures, these compositions can provide a possible support material for a low temperature (i.e. 250C) build environment.

null

['Ader, C.', 'Brosemer, M.', 'Freyer, C.', 'Fricke, H.', 'Hennigs, D.', 'Klocke, F.', 'Kühne, V.', 'Meiners, W.', 'Over, C.', 'Pleteit, H.', 'Stührmann, S.', 'Wirth, I.', 'Wirtz, T.', 'Wissenbach, K.']

2019-12-05T17:12:42Z

2004

Mechanical Engineering

null

['https://hdl.handle.net/2152/78649', 'http://dx.doi.org/10.26153/tsw/5705']

eng

2004 International Solid Freeform Fabrication Symposium

Open

Fraunhofer

Research on Layer Manufacturing Techniques at Fraunhofer

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5da94ad5-eca2-4987-a3e7-e408fc7525bf/download

null

Within the German Fraunhofer-Gesellschaft, the Fraunhofer Alliance Rapid Prototyping unites the competences of 12 institutes in the field of solid freeform fabrication. Covered competences are virtual and computer-aided product planning methods and techniques, the development and integration of materials and processes for different industrial sectors. This paper presents actual research results on layer manufacturing within the Fraunhofer- Gesellschaft based on examples from Fraunhofer ILT »Laser Melting - Direct manufacturing of metal parts with unique properties«, Fraunhofer IFAM »ecoMold - A novel concept to produce molds for plastic injection molding and pressure die casting« and Fraunhofer IPT »Quick manufacture, repair and modification of steel molds using Controlled Metal Build Up (CMB)«.

null

['Zhang, Haiou', 'Jian, Hu', 'Wang, Guilan', 'Qi, He', 'Xie, Yang']

2021-10-13T20:28:39Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88778', 'http://dx.doi.org/10.26153/tsw/15712']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['medium carbon steel parts', 'carbon steel parts', 'Hybrid Deposition and Micro Rolling', 'freeform arc deposition', 'microstructure', 'mechanical properties']

Research on Microstructure and Properties of Medium Carbon Steel Parts Manufactured by HDMR Technology

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6ef7e647-89a2-461c-9433-683dd5edb1ad/download

University of Texas at Austin

A new study on manufacturing medium carbon steel parts by HDMR (Hybrid Deposition and Micro Rolling) technology was carried out, and the microstructures and mechanical properties obtained by HDMR process and freeform arc deposition process respectively were tested and compared in this paper. The experiment results show that: compared with the freeform arc deposition process, the grain size number obtained by HDMR process increased from 3.0 to 9.0；the tensile strength and yield strength were increased by 37.1%, 68.6%，in contrast to the investment casting, increased by 65.4% and 107.7%; compared with the forging, the tensile strength and yield strength were increased by 12.9% and 31.4% respectively. Finally, a medium carbon 45 steel aeronautical part difficult to overlay was manufactured successfully by HDMR technology, thus a new efficient way for additive manufacturing of hard-shaping metal parts at high-quality with low-cost was provided.

null

['Kigure, T.', 'Yamauchi, Y.', 'Niino, T.']

2021-11-16T15:11:38Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90308', 'http://dx.doi.org/10.26153/tsw/17229']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['working curve', 'depth of fusion', 'process parameter', 'part thickness', 'incident energy', 'low-temperature laser sintering', 'laser sintering']

Research on Relationship between Depth of Fusion and Process Parameters in Low-Temperature Laser Sintering Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d1349862-4d1c-4cb7-850b-f1122e2be846/download

University of Texas at Austin

Model of low-temperature laser sintering, in which part warpage during process is prevented by anchoring of parts instead of high-temperature preheating, is discussed. Low-temperature laser sintering process allows powder bed temperature to be lower than those in normal laser sintering process which suppresses parts warpage by preheating powder bed above its recrystallization temperature. When we introduce a new process or material, many experimental examinations are required to decide adequate building conditions. To reduce this process, theoretical process modeling and simulations are carried out. In stereolithography, relationship between laser irradiance and cure depth is known as “working curve,” and used for fundamental equation for this technology. On the other hand, many theoretical models for laser sintering have been introduced, and most of them are thermal models dealing with heat transfer in powder bed. Contrarily, there are few reports concerning measurement and calculation of fusion depth though fusion depth can be obtained easily by experiment and working curve is a useful to determination of building parameters. In this study, working curve which represents relationship between part thickness obtained by monolayer scan and incident energy was investigated. As a result of normalizing the power by the minimum power that can melt the surface of the powder bed, all the plots lay on the same single line. This line, namely master curve, is unique for each powder and useful to finding various parameters.

null

['Seetharaman, Sankaranarayanan', 'Krishnan, Manickavasagam', 'Goh Chung Wen, Francis', 'Ahmed Khan, Niaz', 'Ng Ka Lai, Gary']

2021-10-26T19:59:54Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89570

eng

2016 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'nickel superalloys', 'powder metallurgy', 'microstructure', 'mechanical properties', 'surface finish']

Research Updates on the Additive Manufacturing of Nickel Based Superalloys

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4821b9ea-dc4f-40f3-8052-8d7b2139b840/download

University of Texas at Austin

Over the last decade, additive manufacturing technology has consistently evolved as a sophisticated rapid manufacturing tool that allows direct fabrication of an end-usable part without extensive tooling. The methodology of layer-by-layer fabrication demonstrates the novel prospects of fabricating complex and multifunctional components and the aerospace and automotive industries have been quite successful in adopting various additive technologies for the use in jet engines, power plants and reactor vessels. This article will systematically review the properties of nickel-based superalloys using different additive manufacturing methods. In the first section, the types of additive manufacturing methods are briefly introduced. The properties of Ni superalloy powders and the characterization methods are then discussed. The mechanical properties displayed by additively manufactured Ni superalloys are presented and discussed based on the influence of different processing and post-processing variables.

null

['Hernandez, A.J.', 'Garcia, D.', 'Watanabe, K.I.', 'Gradl, P.R.', 'Wheeler, K.', 'Hafiychuk, Halyna', 'Wicker, R.B.', 'Medina, F.']

2024-03-27T15:56:53Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124494', 'https://doi.org/10.26153/tsw/51102']

en

2023 International Solid Freeform Fabrication Symposium

Open

['DED', 'residual stress', 'deformation', 'overhangs', 'simulation']

RESIDUAL STRESS AND DEFORMATION ANALYSIS OF INCONEL 718 ACROSS VARYING OVERHANGS IN LASER POWDER BLOWN DIRECTED ENERGY DEPOSITION

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9c8b976c-7f3c-4f4f-8e7d-38c7953c1185/download

University of Texas at Austin

Any metal that is subjected to rapid heat and cooling will undergo the development of residual stresses. As they experience intense temperature fluctuations, this will consequently alter the way the material will behave. This issue proves to be of great concern within additive manufacturing. That said, the presence of temperature fluctuations is more prominent in Directed energy deposition (DED), whereas other methods of manufacturing are more prominent in the pre- or post- printing process. This in turn means the deformation, as well as the redistribution of the residual stresses within pieces, are subject to variance by several process parameters set during a print. By using the Inconel 718 alloy feedstock in RPMI’s Laser Powder Directed Energy Deposition (LP-DED) printer, a series of coupons with four different overhang angles and laser power outputs will determine how these changes thermo-mechanically affect the prints through the use of FEA simulations and scans.

null

['Ong, Raymond', 'Beuth, Jack', 'Griffith, Michelle']

2019-09-23T15:40:17Z

2000

Mechanical Engineering

null

['https://hdl.handle.net/2152/75940', 'http://dx.doi.org/10.26153/tsw/3039']

eng

2000 International Solid Freeform Fabrication Symposium

Open

Deposition

Residual Stress Control Issues for Thermal Deposition of Polymers in SFF Processes 209

Conference paper

https://repositories.lib.utexas.edu//bitstreams/62324b41-722c-4473-ad91-7d54c6f2a6c5/download

null

Controlling residual stress-induced warping and other tolerance losses is important for accurately creating parts by solid freeform fabrication (SFF). In this paper, results are presented from warping experiments on plate-shaped acrylonitrile butadiene styrene (ABS) specimensmcreated by an extrusion process used in Shape Deposition Manufacturing (SDM). Experimental results are compared to predictions from both one- and two-dimensional types of residual stress models. In addition to SDM, methods and results from this study are applicable to a number of other solid freeform fabrication processes involving extrusion of polymers or polymer slurries. Results from polymer extrusion are compared with those from existing work on thermal deposition of metals. Unlike metals, polymer deposition shows essentially no stress reduction due to preheating by the deposition process. Due to a greater number of deposited rows, directionality of warping is also greater than in metals. Polymer deposition experiments show that a preheat temperature near the glass transition temperature is needed for essentially no warping. Comparison of predicted and measured curvatures show that a simple 1-D thermomechanical model does not predict warping magnitudes well, but does provide insight into trends in warping as a function of preheat temperature. The effects of successive material deposition are substantial in this process and a 2-D model that includes the effects of successively deposited rows can provide much more accurate curvature predictions.

The authors gratefully acknowledge financial support from the Gintic Institute of Manufacturing Technology and from the National Science Foundation, under grant DMI9700320. A software grant from SDRC allowed use of their software for finite element pre- and post- processing.

null

['Wang, Xiaoqing', 'Chou, Kevin']

2021-10-21T19:37:07Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89431

eng

2015 International Solid Freeform Fabrication Symposium

Open

['Ti-6Al-4V', 'residual stress', 'Vickers indentation', 'microindentation', 'electron beam additive manufacturing']

Residual Stress in Metal Parts Produced by Powder-Bed Additive Manufacturing Processes

Conference paper

https://repositories.lib.utexas.edu//bitstreams/afc66ee3-147b-4c4b-b7fa-3f94923855a3/download

University of Texas at Austin

In this study, residual stresses from the electron beam additive manufacturing (EBAM) and selective laser melting (SLM) processes, due to repeated thermal cycles, were investigated. Residual stresses play a crucial role in part performance, and thus, it is critical to evaluate the process-induced residual stresses in AM parts. Ti-6Al-4V and Inconel 718 parts produced by EBAM and SLM, respectively, were studied in residual stresses using the methodology established by Carlsson et al., a mechanical instrumented indentation technique, which is based on the experimental correlation between the indentation characteristic and the residual stress. The results show that the Ti-6Al-4V EBAM parts have a compressive residual stress in both Z-plane and X-plane, while the Inconel 718 SLM parts show a tensile stress and a compressive stress in the Z-plane and X-plane, respectively. Besides, the Ti-6Al-4V parts have lower absolute value of residual stress than the Inconel 718 parts. Moreover, the Vickers hardness values of the parts built using SLM and EBAM are comparable to the literature data.

null

['Yadroitsava, I.', 'Yadroitsev, I.']

2021-10-20T21:18:13Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89363

eng

2015 International Solid Freeform Fabrication Symposium

Open

['Direct Metal Laser Sintering', 'residual stress', 'metals']

Residual Stress in Metal Specimens Produced by Direct Metal Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6724af47-327a-46d1-8afb-a9bef53d3240/download

University of Texas at Austin

Direct Metal Laser Sintering (DMLS) has great potential in additive manufacturing because it allows the production of full-density complex parts with the desired inner structure and surface morphology. High temperature gradients, as a result of the locally concentrated energy input, lead to residual stresses, crack formation and part deformations during processing or after separation from the supports and the substrate. In this study, an X-ray diffraction technique and numerical simulation were used for investigation of the residual stress in DMLS samples fabricated from stainless steel 316L and Ti6Al4V alloy. Conclusions regarding directions and values of stresses in DMLS objects are given.

null

['Andurkar, Mohanish', 'Suzuki, Toshikazu', 'Omori, Masanao', 'Prorok, Bart', 'Gahl, John', 'Thompson, Scott']

2021-12-06T22:59:09Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90707', 'http://dx.doi.org/10.26153/tsw/17626']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['FWHM', 'selective laser melting', 'microhardness', 'nickel superalloy', 'additive manufacturing']

Residual Stress Measurements via X-ray Diffraction Cos α Method on Various Heat-Treated Inconel 625 Specimens Fabricated via Laser-Powder Bed Fusion

Conference paper

https://repositories.lib.utexas.edu//bitstreams/cbab31b9-f41e-41ec-8cc1-3c649a69b249/download

University of Texas at Austin

The residual stress and hardness of Inconel 625 fabricated using Laser Powder Bed Fusion (L-PBF) were experimentally investigated. As-built Inconel 625 samples were subjected to three different heat-treatment temperatures of 700℃, 900℃, 1050℃ for one hour. Effects of these three-stress relieving heat treatment temperatures on the nature and value of residual stress were studied. Residual stress measurements were recorded using a portable X-ray system. The system calculated residual stress using the cos α method. The Full Width Half Maximum (FWHM) of diffraction peaks in all samples were measured. The results indicate that tensile residual stress was present on the surface of as-built L-PBF sample and compressive residual stress on the surface of heat-treated samples due to stress relief. Debye-Scherrer (D-S) ring positions were measured using the cos α method and compared with a reference wrought Inconel 625 ring position. Vickers microhardness and residual stress were found to be positively correlated.

null

['Martina, Filomeno', 'Roy, Matthew', 'Colegrove, Paul', 'Williams, Stewart W.']

2021-10-12T20:21:23Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88732', 'http://dx.doi.org/10.26153/tsw/15666']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['wire + arc additive manufacturing', 'residual stress', 'high-pressure interpass rolling', 'high-pressure rolling', 'Ti-6Al-4V', 'aerospace']

Residual Stress Reduction in High Pressure Interpass Rolled Wire+Arc Additive Manufacturing Ti-6Al-4V Components

Conference paper

https://repositories.lib.utexas.edu//bitstreams/541f9720-e395-4cb6-acc0-ed5f0b95d855/download

University of Texas at Austin

Wire+arc additive manufacturing (WAAM) components are characterised by high residual stress due to the many consecutive deposition passes. Residual stress results in distortion once the part is unclamped. High-pressure rolling was investigated as a way to address this issue in Ti–6Al–4V linear parts. Rolling loads of 50 kN and 75 kN were investigated. Residual stress measurements, performed with the contour method, showed rolling was successful in reducing residual stress substantially, especially at the interface between the part and the baseplate. High-pressure interpass rolling is likely to facilitate the implementation of WAAM for the manufacture of structural aerospace components.

null

['Nickel, A.', 'Barnett, D.', 'Link, G.', 'Prinz, F.']

2019-03-12T16:51:35Z

1999

Mechanical Engineering

null

['https://hdl.handle.net/2152/73602', 'http://dx.doi.org/10.26153/tsw/744']

eng

1999 International Solid Freeform Fabrication Symposium

Open

['Layered Manufacturing', 'Residual stresses']

Residual Stresses in Layered Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/83c1c396-7340-45b6-98b6-4f548109eedc/download

null

Layered Manufacturing processes accumulate residual stresses during materialbuildup. These stresses may cause part warping and layer delamination. This paper presents work done on investigating residual stress accumulation andp(i,rt distortion of Layered Manufactured artifacts. A simple analyticaLmodel was developed and used to determine how the number of layers and the layer thickness influences part warping. Resllits show that thin layers produce lower part deflection as compared with depositing fewer and thicker layers. In addition to the analytical work, a finite element model wasdeveloped and used to illvestigate the deposition pattern's influence on. the part deflection. Finite element model and corresponding experimental analysis showed that the geometry of the deposition pattern significantly affects the resulting part distortion. This finite element model was also used to investigate an inter-layer surface defect,. known as the Christmas Thee Step, that is associated with Shape Deposition Manufacturing. Results indicate that the features of this defect are influenced only by the material deposited close. to the part·surface and the particular material deposited. The step is not affected by the deposition pattern.

null

['Mercelis, Peter', 'Kruth, Jean-Pierre']

2020-02-20T20:24:09Z

8/24/05

Mechanical Engineering

null

https://hdl.handle.net/2152/80049

eng

2005 International Solid Freeform Fabrication Symposium

Open

Selective Laser Sintering

Residual Stresses in Selective Laser Sintering and Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/26460874-3788-4112-9545-4e79cfc6eabe/download

null

['Yerazunis, W.', 'Weiss, A.', 'Radyjowski, P.', 'Cottrell, R.']

2023-04-03T17:51:20Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117732', 'http://dx.doi.org/10.26153/tsw/44611']

eng

2022 International Solid Freeform Fabrication Symposium

Open

resin

Resin Development for On-Orbit Fabrication of Spacecraft Structures by Direct Solar Photopolymerization

Conference paper

https://repositories.lib.utexas.edu//bitstreams/70b9d92d-03ea-4d95-af68-dd2e570b1790/download

null

One of the paradoxes of spacecraft design is that spacecraft are destined to operate in orbit where maneuvering thruster firings produce stresses below 0.01 G, but the spacecraft must be strong enough (and heavy enough) to survive the roughly 10 G’s of linear acceleration and 50 G’s of vibration in a rocket launch. In this paper, we follow on previous work to develop and test an alternative: the post-launch freeform additive manufacture of a major communications satellite structural element in UV cured resin, using solar UV to trigger polymerization. Here we develop the chemistry of a UV curable liquid resin that not only has a very low (below our chamber limit of 0.2 kPa) vapor pressure post-degassing, but also is not dependent on oxygen presence to activate the thermal inhibitors that prevent premature polymerization. In tests, we successfully freeform 3D printed a small (60 mm) parabolic dish at chamber limit pressure using simulated solar UV flooding the chamber.

null

['Ahsan, Nazmul', 'Habib, Ahasan', 'Khoda, Bashir']

2021-10-18T22:48:25Z

2014

Mechanical Engineering

null

https://hdl.handle.net/2152/89281

eng

2014 International Solid Freeform Fabrication Symposium

Open

['Additive Manufacturing', 'build direction', 'fabrication', 'resource utilization']

Resource Based Build Direction in Additive Manufacturing Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/bdb9fccd-16f7-4d7f-bdab-8a1aaab0317b/download

University of Texas at Austin

Three dimensional free-form geometric shapes can be built by putting layers upon layer in a predefined direction via Additive Manufacturing (AM) processes. The fabrication processes require computational as well as physical resources and can vary not only upon the product but its process plan. Overly simplified process plan may expedite the pre-fabrication techniques, but may create difficulty during fabrication of those slices. For an example, slices with concavity or discrete contour plurality may introduce deposition discontinuity, over deposition, and higher build time during the fabrication. These issues demand more resources there by affecting the part quality and fabrication cost. In this work, we focus upon the build direction of AM process plan to address the fabrication and resource utilization. First, a set of uniform build direction is identified and the object is discretized using a set of critical points considering the object concavity along the build direction. Cutting planes are generated and the object is discretized into strips and each strip is analyzed for contour plurality and the build directions are quantified through the allocation of importance factors. The optimal build direction thus found will result in lowest possible fabrication complexity. The proposed methodology is implemented and presented with a sample example in this paper.

null

['Tepper, C.', 'Utsch, J.', 'Zarges, J.', 'Weigold, M.']

2024-03-26T23:24:23Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124449', 'https://doi.org/10.26153/tsw/51057']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['resource efficiency', 'hybrid-additive manufacturing', 'DED', 'robot']

Resource Efficiency of the Robot-Based Hybrid Additive Manufacturing Chain

Conference paper

https://repositories.lib.utexas.edu//bitstreams/46ff820b-a74b-42b0-8d13-21d72fafe8c7/download

University of Texas at Austin

Combining additive and subtractive metal processes to a hybrid additive manufacturing chain not only enables the production of parts with application-oriented design but also leads to increased resource efficiency especially when combined in an industrial robotic cell. Compared to parts manufactured through subtractive processes from full material the hybrid additive manufacturing chain is considered to be resource efficient due to reduced material consumption. However, the energy consumption of the hybrid additive process is considered higher because of the use of laser for the additive process. It is assumed that the decreased material consumption outweighs the higher energy consumption regarding the resource efficiency but until now it is not investigated. Therefore, in this paper the resource consumption of the robot-based hybrid additive manufacturing chain including the wire based direct energy deposition process and the milling process is analysed through measurements during experiments and compared to subtractive processes using the carbon footprint as a reference.

null

['Nandi, Indrajit', 'Ahmad, Nabeel', 'Shamsaei, Nima', 'Shao, Shuai']

2023-01-26T15:41:05Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117320', 'http://dx.doi.org/10.26153/tsw/44201']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Additive manufacturing', 'Laser powder bed fusion', 'Crystal plasticity finite element simulation', 'Tensile fracture']

Revealing Texture Induced Abnormal Tensile Deformation Behavior in Additively Manufactured Haynes 282 Using Crystal Plasticity Simulations

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f4e4bc1c-8733-4941-9122-ce9cda048adb/download

null

A ductile fracture typically features a dimpled surface appearance because of micro-void coalescence and a circular cup-and-cone morphology. Tensile fracture surfaces of additively manufactured Haynes 282, a nickel-base superalloy, in this work exhibit an elliptical shape – an aberration to classic fracture surface. Both microstructural characterization and fractography were performed using scanning electron microscopy (SEM) on the tensile deformed surfaces to assess the fracture behavior. To gain better mechanistic insights into the governing factors of this elliptical shape fracture, crystal plasticity finite element (CPFE) simulations were performed using the experimentally calibrated material parameters. Uniaxial tensile loading simulations were carried out on a polycrystalline aggregate where the initial texture was varied to the CPFE simulation to emulate the experimental microstructure. The mechanical response and shape of the fracture surface obtained from the simulations were compared with the experimental tensile deformed surface to illustrate the texture dependent deformation inhomogeneity.

null

['Rhyne, Breanna J.', 'Post, Brian K.', 'Chesser, Phillip', 'Roschli, Alex', 'Love, Lonnie J.']

2021-11-08T21:10:49Z

2017

Mechanical Engineering

null

['https://hdl.handle.net/2152/90042', 'http://dx.doi.org/10.26153/tsw/16963']

eng

2017 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'reverse engineering', 'transhumeral prosthetic design', 'prosthetics']

Reverse Engineering a Transhumeral Prosthetic Design for Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/77af531d-8176-4397-860b-c44c47f73bec/download

University of Texas at Austin

The customization and time savings additive manufacturing (AM) offers has been applied to construct prosthetics. However, prosthetics produced using AM rarely resemble the original appendage they are intended to replace. This report details the engineering of a transhumeral prosthetic design for AM. A 3D scan of a subject’s existing arm and computer-aided design (CAD) were used to create a mirrored prosthetic, which appeared aesthetically like the existing arm. The process and complexities of integrating mechanical components for basic actuation into a patient-custom prosthetic are discussed. A simple demonstration of the process is provided. The same methodology can be applied to more intricate prosthetics. This work aims to inspire subsequent research into well-functioning, custom prosthetics that can be generated relatively quickly through 3D scanning and AM.

null

['Rosen, David W.', 'Jeong, Namin']

2021-10-06T21:09:11Z

2012

Mechanical Engineering

null

['https://hdl.handle.net/2152/88444', 'http://dx.doi.org/10.26153/tsw/15381']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['image processing methods', 'microstructure models', 'CAD modeling', 'reverse engineering']

Reverse Engineering of Materials Using Image Processing Methods for CAD-Material Integration

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a734700c-d379-482b-a725-549e0935332c/download

University of Texas at Austin

Integration of material composition, microstructure, and mechanical properties with geometry information enables many product development activities, including design, analysis, and manufacturing. In this paper, we investigate the application of image processing methods for constructing models of material microstructure. These microstructure models can be integrated into CAD models to enable the utilization of material process-structure-property relationships during CAD modeling. Engineering design is enabled by integration of computational materials design methods with these relationships. Using 2D images and 3D voxel datasets, the image processing methods can be used to find microstructure features, such as grain boundaries or particle or fiber reinforcements, by finding edges and extracting features from those edges. This paper will focus on three different image processing methods, which will be applied to microstructure images of materials fabricated by additive manufacturing.

null

['Jeong, Namin', 'Rosen, David W.']

2021-10-11T21:24:56Z

2013

Mechanical Engineering

null

['https://hdl.handle.net/2152/88648', 'http://dx.doi.org/10.26153/tsw/15582']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['reverse engineering', 'CAD systems', 'linear microstructure features', 'surfacelet based methods', 'additive manufacturing', 'microstructure features', 'material integration']

Reverse Engineering of Materials Using Surfacelet-Based Methods for CAD-Material Integration

Conference paper

https://repositories.lib.utexas.edu//bitstreams/83161e12-a640-4382-aa44-99f54290b1d9/download

University of Texas at Austin

To integrate material information into CAD systems, geometric features of material microstructure must be recognized and represented, which is the focus of this paper. Linear microstructure features, such as fibers or grain boundaries, can be found computationally from microstructure images using surfacelet based methods, which include the Radon or Radon-like transform followed by a wavelet transform. By finding peaks in the transform results, linear features can be recognized and characterized by length, orientation, and position. The challenge is that often a feature will be imprecisely represented in the transformed parameter space. In this paper, we demonstrate surfacelet-based methods to recognize microstructure features in parts fabricated by additive manufacturing. We will provide an explicit mathematical method to recognize and to quantify linear geometric features from an image.

null

['Christensen, Jon', 'Bandyopadhyay, Amit']

2019-02-22T20:00:58Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73469', 'http://dx.doi.org/10.26153/tsw/619']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['CCD camera', 'CAD']

Reverse Engineering of Polymeric Solid Models Using Refractive Index Matching (RIM)

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ba869d00-c127-4b9a-80cc-e8106e0a0e73/download

null

Reverse engineering (RE) techniques allows the creation of 3-D CAD files from a solid model. The benefits of reverse engineering are not >new. to the industrial design and manufacturing<arena though wide spread applications are yet to be seen. A novel approach is used to reverse engineer polymeric parts with its internal features in aJow. cOst, non-destructive manner. Solids created from polymers with anindex of refraction matching thatof an immersion liquid are reverSe engineered using a CCD .calllera. The images are then used to create digital solid models from a physical··model. Design·and development of this novel ilow costtool for reverse engineering ofpolymeric solid models is described in this paper.

null

['Steinberg, Ben', 'Razdan, Anshuman', 'Farin, Gerald']

2019-02-20T17:45:13Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73457', 'http://dx.doi.org/10.26153/tsw/609']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['CAD', 'BSpline']

Reverse Engineering Trimmed NURB Surfaces From Laser Scanned Data

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a8491c4c-9c3b-4d64-907a-af712389f91b/download

null

A common reverse engineering problem is to convert several hundred thousand points collected from the surface of an object via a digitizing process, into a coherent geometric model that is easily transferred to a CAD software such as a solid modeler for either design improvement or manufacturing and analysis. These data are very dense and make data-set manipulation difficult and tedious. Many commercial solutions exist but involve time consuming interaction to go from points to surface meshes such as BSplines or NURBS (Non Uniform Rational BSplines). Our approach differs from current industry practice in that we produce a mesh with little or no interaction from the user. The user can produce degree 2 and higher BSpline surfaces and can choose the degree and number ofsegments as parameters to the system. The BSpline surface is both compact and curvature continuous. The former property reduces the large storage overhead, and the later implies a smooth can be created from noisy data. In addition, the nature ofthe BSpline allows one to easily and smoothly alter the surface, making re-engineering extremely feasible. The BSpline surface is created using the principle ofhigher orders least squares with smoothing functions at the edges. Both linear and cylindrical data sets are handled using an automated parameterization method. Also, because ofthe BSpline's continuous nature, a multiresolutional-triangulated mesh can quickly be produced. This last fact means that an STL file is simple to generate. STL files can also be easily used as input to the system.

null

['Buchele, S. F.', 'Ellingson, W. A.']

2018-12-07T15:49:28Z

1997

Mechanical Engineering

doi:10.15781/T21G0JF4K

http://hdl.handle.net/2152/71438

eng

1997 International Solid Freeform Fabrication Symposium

Open

['Solid modeling', 'CAD']

Reverse Engineering: Algebraic Boundary Representations to Constructive Solid Geometry

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b7612437-6279-4ba0-a7e3-77cb0c90b341/download

null

Recent advances in reverse engineering have focused on recovering a boundary representation (b-rep) of an object, often for integration with rapid prototyping. This boundary representation may be a 3-D point cloud, a triangulation of points, or piecewise algebraic or parametric surfaces. This paper presents work in progress to develop an algorithm to extend the current state of the art in reverse engineering of mechanical parts. This algorithm will take algebraic surface representations as input and will produce a constructive solid geometry (CSG) description that uses solid primitives such as rectangular block, pyramid, sphere, cylinder, and cone. The proposed algorithm will automatically generate a CSG solid model of a part given its algebraic b-rep, thus allowing direct input into a CAD system and subsequent CSG model generation.

null

['Griffin, Alair', 'McMillin, Scott', 'Griffin, Curtis', 'Knox, Dr. Charles']

2018-12-07T15:59:38Z

1997

Mechanical Engineering

doi:10.15781/T2WP9TS91

http://hdl.handle.net/2152/71439

eng

1997 International Solid Freeform Fabrication Symposium

Open

['3D model', 'magnetic resonance']

Reverse Engineering: Practical Considerations for Rapid Prototyping

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a9671f2d-7e09-434e-b5dc-017abc0a2544/download

null

It is now possible to generate threedimensional (3D) solid models of extremely complicated systems from which full plastic replicas can be generated using a variety of rapid prototyping technologies. The cycle time has been reduced to several hours, where it previously took months to produce a comparable prototype. The process of taking a design into the 3D environment, whether UNIX-or PC-based, is getting easier and fairly straightforward.The design engineer interested in producing a 3D model from unique data sets such as computer tomography (CT) or magnetic resonance (MR) image data is particularly concerned with time, cost, accuracy, and conversion problems. This paper presents an approach that Lone Peak Engineering, Inc. (LPE) has used that allows them to successfully handle CT and MR data for reverse engineering (RE).

null

['Flood, Aaron', 'Liou, Frank']

2021-11-03T20:13:21Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89920

eng

2017 International Solid Freeform Fabrication Symposium

Open

['methodology', 'simulation', 'validation', 'laser based metal additive manufacturing']

Review of AM Simulation Validation Techniques

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a144f24e-4567-4367-b030-5071f24e30cd/download

University of Texas at Austin

Due to the complexity of Additive Manufacturing (AM), it can require many trial runs to obtain processing parameters which produce a quality build. Because of this trial and error process, the drive for simulations of AM has grown significantly. Simulations only become useful to researchers if it can be shown that they are true representations of the physical process being simulated. All simulations have different methods of validation to show that they are an accurate representations of the process. This paper explores the various methodologies for validation of laser based metal AM simulations, focusing mainly on the modeling of the thermal processes and other characteristics derived from thermal history. It will identify and explain the various validation techniques, specifically looking at the frequency of reported use of each technique.

null

['Crisp, Tyler G.', 'Weaver, Jason M.']

2021-12-07T18:17:34Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90746', 'http://dx.doi.org/10.26153/tsw/17665']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['big area additive manufacturing', 'Oak Ridge National Laboratory', 'Cincinnati Inc', 'large area additive manufacturing', 'large format 3D printing', 'hybrid manufacturing', 'functionally graded material', 'composite additive manufacturing']

Review of Current Problems and Developments in Large Area Additive Manufacturing (LAAM)

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f6dda843-df71-4745-b9bb-d02d610af14f/download

University of Texas at Austin

Large Area Additive Manufacturing (LAAM), also known as Big Area Additive Manufacturing (BAAM), is a screw extrusion, pellet-fed additive manufacturing technology. The large build area, rapid build speed, and inexpensive pelletized feedstock of LAAM are major advantages over conventional AM methods. LAAM has a large variety of applications in areas including energy, automotive, aerospace, high volume production, and composite molds. However, LAAM is not without its challenges. The largest challenges LAAM faces include mechanical properties, uniformity and precision, and predictability of composite material properties. The goal of this paper is to present current research regarding challenges in LAAM, methods of addressing those challenges, developments, and applications, as well to highlight further research to be done.

null

['Lorenz, K.A.', 'Jones, J.B.', 'Wimpenny, D.I.', 'Jackson, M.R.']

2021-10-19T17:59:48Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89311

eng

2014 International Solid Freeform Fabrication Symposium

Open

['Hybrid Manufacturing', 'Hybrid Manufacturing Systems', 'laser-based Additive Manufacturing', 'Computer Numerical Controlled', 'history']

A Review of Hybrid Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/52a295cf-0b72-4b6f-9280-8bf99f89d239/download

University of Texas at Austin

In recent years the combination of laser-based Additive Manufacturing and Computer Numerical Controlled (CNC) machining has become increasingly popular, with several machine tool manufacturers exhibiting products based on different machine tool configurations. This technology, widely known as Hybrid Manufacturing, generally exploits Directed Energy Deposition processes using powder feedstock that is fed into a melt pool created by a laser. Although Directed Energy Deposition processes predate powder bed fusion Additive Manufacturing (at least in terms of coating and repair applications), commercialization of Hybrid Manufacturing systems is still very much in its infancy. However, they do offer clear advantages, combining a high deposition rate together with the accuracy and surface finish associated with machining. This paper presents the history of the development of Hybrid Manufacturing Systems (HMS), dating back from work undertaken in the mid 1990s through to the present day. The relative merits of different material deposition approaches are compared and some of the key technical challenges which remain are highlighted and discussed.

null

['Ruan, Jianzhong', 'Sparks, Todd E.', 'Fan, Zhiqiang', 'Stroble, Jacquelyn Kay', 'Panackal, Ajay', 'Liou, Frank']

2020-02-28T15:37:53Z

2006

Mechanical Engineering

null

['https://hdl.handle.net/2152/80112', 'http://dx.doi.org/10.26153/tsw/7133']

eng

2006 International Solid Freeform Fabrication Symposium

Open

selective laser sinstering

A Review of Layer Based Manufacturing Processes for Metals

Conference paper

https://repositories.lib.utexas.edu//bitstreams/491b06d4-82c1-4ffb-aec1-e5be57982feb/download

null

The metal layered manufacturing processes have provided industries with a fast method to build functional parts directly from CAD models. This paper compares current metal layered manufacturing technologies from including powder based metal deposition, selective laser sinstering (SLS), wire feed deposition etc. The characteristics of each process, including its industrial applications, advantages/disadvantages, costs etc are discussed. In addition, the comparison between each process in terms of build rate, suitable metal etc. is presented in this paper.

null

['Zhang, Hui', 'Guo, Yanling', 'Jiang, Kiayi', 'Bourell, David L.', 'Zhao, Dejin', 'Yu, Yueqiang', 'Wang, Puxuan', 'Li, Zhipeng']

2021-10-27T22:22:25Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89632

eng

2016 International Solid Freeform Fabrication Symposium

Open

['wood-plastic composites', 'selective laser sintering', 'historical review']

A Review of Selective Laser Sintering of Wood-Plastic Composites

Conference paper

https://repositories.lib.utexas.edu//bitstreams/cf50047a-8c5d-4b28-9698-f0fb769b9e6f/download

null

Eco-friendly wood-plastic composites were firstly proposed to be used as the raw materials of rapid prototyping in 2002, and successfully applied in Selective Laser Sintering (SLS) two years later. These composites were mixed by different kinds of wood powder, plastic powder and other additives. Different from polymer, ceramics, metals and their composites, wood-plastic composites are new types of sustainable and low-price feedstock of SLS. This paper presents the development of the research of wood-plastic composites applied to SLS over the past decade. It contains the preparation and characterizations of wood-plastic composites, the study of temperature fields and molecular dynamics simulation of sintering wood-plastic composites, the effects of processing parameters on the forming accuracy and mechanical properties of sintered parts, and the post-treating process of wood-plastic composite parts. At last, it introduces the application fields of laser sintered wood-plastic composites parts.

null

['Yasa, Evren', 'Ersoy, Kivilcim']

2021-11-10T21:36:54Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90183', 'http://dx.doi.org/10.26153/tsw/17104']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'polymer matrix composites', 'layered manufacturing', 'carbon fiber reinforced polymers', 'rapid manufacturing']

A Review of the Additive Manufacturing of Fiber Reinforced Polymer Matrix Composites

Conference paper

https://repositories.lib.utexas.edu//bitstreams/14c3e205-f1c1-4bde-9744-fdc6b67fc8b0/download

University of Texas at Austin

Additive manufacturing (AM), also referred to as 3D printing, has gained popularity due to the recent developments and market trends especially in the last decades. The main advantages of AM are its capability of producing parts with high geometrical complexity at almost no added cost, short lead times, weight reduction, less efforts for assembly and suitability for customization as well as for low volume production or even single parts. Moreover, some applications may need materials with unusual combinations of properties, which cannot be provided only by metals, polymers or ceramics. For such applications, composite materials combining two or more materials allow having the preferred properties combined in a single material. Thus, AM, which can be defined as a process of adding materials to produce objects directly from its CAD model in successive layers in contrast to subtractive processes, is gaining significance for critical applications using composite materials. This paper thus presents a detailed review of AM of polymers reinforced with chopped / continuous fibers and the influence of this reinforcement on the mechanical performance of composite parts, mainly focusing on the Fused Deposition Modelling (FDM) process. On one hand, the reviewed studies on the FDM of composites mainly point out that that the mechanical performance is significantly enhanced in contrast to polymers with no reinforcement. Yet, it is also evident that the mechanical performance of FDM composites is highly dependent on the build direction and porosity. Thus, there is still a wide range of gaps to be studied for replacing metallic components by AM composites.

null

['Zeng, Kai', 'Pal, Deepankar', 'Stucker, Brent']

2021-10-06T21:43:20Z

2012

Mechanical Engineering

null

['https://hdl.handle.net/2152/88453', 'http://dx.doi.org/10.26153/tsw/15390']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['laser sintering', 'selective laser melting', 'finite element modeling', 'thermal analysis']

A Review of Thermal Analysis Methods in Laser Sintering and Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4e1e8e51-b86d-47be-a490-746775febdcd/download

University of Texas at Austin

Thermal analysis of laser processes can be used to predict thermal stresses and microstructures during processing and in a completed part. Thermal analysis is also the basis for feedback control of laser processing parameters in manufacturing. A comprehensive literature review of thermal analysis methods utilized in Laser Sintering (LS) has been undertaken. In many studies, experimental methods were commonly used to detect and validate thermal behavior during processing. Coupling of thermal experiments and FEM analyses were utilized in many of the latter studies. Analytical solutions were often derived from the Rosenthal solution and other established theories. In recent years, some temperature measuring systems have been implemented to validate the simulation results. The main characteristics of LS temperature distribution and effects of process parameters to temperature are also summarized and shown by a case study.

null

['Norris, Marshall', 'Fidan, Ismail', 'Allen, Michael']

2023-01-26T14:23:58Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117305', 'http://dx.doi.org/10.26153/tsw/44186']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Additive manufacturing', 'Extruded Material', '3D Printing', 'Powdered Metal', 'Rheology']

Rheological Characterization of Room Temperature Powder Metal Paste for Extruded Material Modeling

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ca5879cb-2155-4aa7-b502-be28433fded6/download

null

Powder metals have been used in Additive Manufacturing (AM) processes such as injection molding, extrusion, and slip casting for decades. Recent innovations in the Fused Filament Fabrication (FFF) have provided the opportunity to mix powder metals with a binding thermoplastic at elevated temperatures to create 3D components. This research attempts to define the rheological characteristics of paste materials used to produce 3D components at room temperature using powder metals that will provide the following three outcomes: material that will flow under low shear stress, green strength to provide structural support of material deposited on top and prevent deformation under gravitational load, and once cured to provide material properties that are comparable to those of materials produced by traditional means. The purpose of this research is to determine if powder metal components can be produced by FFF at room temperature while maximizing the powder metal composition in the mixture.

null

['Ajinjeru, Christine', 'Kishore, Vidya', 'Liu, Peng', 'Hassen, Ahmed Arabi', 'Lindahl, John', 'Kunc, Vlastimil', 'Duty, Chad']

2021-11-02T18:09:23Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89849

eng

2017 International Solid Freeform Fabrication Symposium

Open

['processing condition', 'high temperature polymers', 'thermoplastics', 'deposition system', 'extrusion-based additive manufacturing']

Rheological Evaluation of High Temperature Polymers to Identify Successful Extrusion Parameters

Conference paper

https://repositories.lib.utexas.edu//bitstreams/80c9244a-e875-49ef-b2e7-4f6cf167abef/download

University of Texas at Austin

With the advancements in additive manufacturing (AM), several high temperature thermoplastics are being explored as potential AM feedstocks. Some of these high-performance thermoplastics include; polyetherimides (PEI), polyphenylsulfones (PPSU/F), poly (ether ketone ketone)s (PEKK) and polyphenylene sulfide (PPS) as well as their reinforced composites. Most of these advanced resins tend to be more expensive than commodity plastics such as acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA), and their processing parameters have not been determined for most AM systems. This paper demonstrates a method for identifying the appropriate processing conditions for extrusion-based AM deposition systems, in which a material is forced through an orifice at a given flow rate. The pressure required to extrude a shear-thinning thermoplastic at a given shear rate is calculated based on viscoelastic properties of the polymer melt and compared against maximum system pressure to predict successful extrusion. An evaluation of several candidate materials is presented on the Big Area Additive Manufacturing extrusion-based platform.

null

['Ramesh, Srikanthan', 'Gerdes, Sam', 'Lau, Sharon', 'Mostafavi, Azadeh', 'Kong, Zhenyu', 'Johnson, Blake N.', 'Tamayol, Ali', 'Rao, Prahalada', 'Rivero, Iris V.']

2021-11-09T20:35:48Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90160', 'http://dx.doi.org/10.26153/tsw/17081']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['printability', 'muscle regeneration', 'in-situ monitoring', 'bioprinting', 'C2C12 myoblasts']

Rheological, In Situ Printability and Cell Viability Analysis of Hydrogels for Muscle Tissue Regeneration

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ad3519f1-7469-4458-9805-be14e7a9c592/download

University of Texas at Austin

Advancements in additive manufacturing have made it possible to fabricate biologically relevant architectures from a wide variety of materials. Hydrogels have garnered increased attention for the fabrication of muscle tissue engineering constructs due to their resemblance to living tissue and ability to function as cell carriers. However, there is a lack of systematic approaches to screen bioinks based on their inherent properties, such as rheology, printability and cell viability. Furthermore, this study takes the critical first-step for connecting in-process sensor data with construct quality by studying the influence of printing parameters. Alginate-chitosan hydrogels were synthesized and subjected to a systematic rheological analysis. In situ print layer photography was utilized to identify the optimum printing parameters and also characterize the fabricated three-dimensional structures. Additionally, the scaffolds were seeded with C2C12 mouse myoblasts to test the suitability of the scaffolds for muscle tissue engineering. The results from the rheological analysis and print layer photography led to the development of a set of optimum processing conditions that produced a quality deposit while the cell viability tests indicated the suitability of the hydrogel for muscle tissue engineering applications.

null

['Xia, Bin', 'Krueger, Paul S.']

2021-11-18T17:45:15Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90444', 'http://dx.doi.org/10.26153/tsw/17365']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['particulate composite', 'viscosity', 'rheology', 'particulate suspension', 'additive manufacturing', '3-D printing', 'capillary flow', 'jamming condition', 'volume fraction', 'particle size']

Rheology and Applications of Particulate Composites in Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7bc74119-28bb-461a-827d-640b55171419/download

University of Texas at Austin

To provide different functionalities such as electrical conductivity or magnetic permeability, particulate composites have been utilized widely in additive manufacturing. These types of materials are usually formulated with different functional particles and shear thinning non-Newtonian fluids such as polymer melts and silicone. The materials are viscous non-Newtonian suspensions during formulation and printing, and their rheology is a key factor for the processing. This paper will concentrate on suspensions with micron-sized particles, and discuss the rheology and overall flow behavior in capillaries scaled appropriately for additive manufacturing applications (around 1 mm ID). Micron size glass beads and shear thinning silicone are used to demonstrate the impact of particle volume fraction on the shear thinning behavior. The impact of particle and capillary size on viscosity and jamming conditions will be discussed. Previous models based on Newtonian fluids and in free flowing conditions will also be reviewed and compared.

null

['Zhu, Cheng', 'Smay, James E.']

2021-09-30T19:39:59Z

9/23/10

Mechanical Engineering

null

['https://hdl.handle.net/2152/88286', 'http://dx.doi.org/10.26153/tsw/15227']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['3D mesoscale structures', 'direct-write asssembly', 'colloidal gels', 'rheology', 'shear history', 'thixotropic rheological', 'concentrated colloidal gels', 'flow behavior']

Rheology and Flow Behavior of Concentrated Colloidal Gels for Direct-Write Assembly of 3D Mesoscale Structures

Conference paper

https://repositories.lib.utexas.edu//bitstreams/976f50aa-d420-4b05-b275-89aa5f0079d8/download

University of Texas at Austin

3D mesoscale structures with various patterns have been successfully fabricated by direct-write assembly of concentrated colloidal gels. Geometric fidelity of these structures is very important to functionality as devices and has been closely tied to gels microstructure dynamics, which depends on the rheology and shear history. Here, Al2O3 gels were prepared and employed as model materials. A thixotropic rheological model was developed to show the time dependent behavior of gels structure during shear flow. The model accounts for structure formation and attrition, each with a shear history dependent rate constant. The true wall stress was measured by correcting the end effects and wall slip. The extrusion flow dynamics of the gel was simulated by using CFD method to disclose the structure profiles of extrusion filaments and predict the structure evolution of as-deposited filaments.

null

['Crocket, R.S.', 'Calvert, P.D.']

2018-12-07T17:13:26Z

1997

Mechanical Engineering

doi:10.15781/T2707X82M

http://hdl.handle.net/2152/71452

eng

1997 International Solid Freeform Fabrication Symposium

Open

['spreading bead', 'Deposition']

Rheology and Solid Freeform Fabrication: Modeling Material Flow in Deposition Techniques

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2b5a45e1-703f-4ce1-a1b0-c16cac79a1d7/download

null

['Carton, Molly Aubrey', 'Nandi, Chandrakana', 'Anderson, Adam', 'Zhao, Haisen', 'Darulova, Eva', 'Grossman, Dan', 'Lipton, Jeffrey Ian', 'Schulz, Adriana', 'Tatlock, Zachary']

2021-12-06T23:41:46Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90720', 'http://dx.doi.org/10.26153/tsw/17639']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['parallel printing', 'simultaneous extrusion', '3D printer', '3D printing', 'development', 'roadmap']

A Roadmap Towards Parallel Printing for Desktop 3D Printers

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8ef487e7-d4ce-4ea7-97ef-c3ef1e11666a/download

University of Texas at Austin

3D printers with multiple extruders (or multiheaded printers) are common in the desktop fabrication community, but are primarily used for multi-color or multi-material printing, using only one extruder at a time. What if these multiheaded desktop printers could also be used for simultaneous parallel printing? While this is a relatively unexplored direction, we argue that it deserves further investigation: a flexible, robust, and affordable parallel printing ecosystem could significantly reduce fabrication time for many applications and further enhance the value of desktop rapid prototyping. We propose a research agenda to explore the development of a parallel printing pipeline, and summarize our observations from a preliminary investigation of simultaneous extrusion. We hope this vision will encourage and guide future research in developing hardware, firmware, and slicers to facilitate parallel 3D printing.

null

['Smay, James E.', 'Cesarano III, Joseph', 'Lin, Shawn Y.', 'Stuecker, John N.', 'Lewis, Jennifer A.']

2019-10-09T16:39:06Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76162', 'http://dx.doi.org/10.26153/tsw/3251']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Photonic

Robocasting of Photonic Band Gap Structures

Conference paper

https://repositories.lib.utexas.edu//bitstreams/85410dc1-0e85-4ce0-8b31-a1ac000d6a3c/download

null

['Stuecker, John N.', 'Cesarano III, Joseph', 'Smay, James E.']

2019-10-18T17:02:51Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76262', 'http://dx.doi.org/10.26153/tsw/3351']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Filtration

Robocasting Periodic Lattices for Advanced Filtration

Conference paper

https://repositories.lib.utexas.edu//bitstreams/fb74c9d7-f6bc-4ca3-a4f2-3fee4b1e9027/download

null

Ceramic filters used in the casting of molten metals are commonly created by slurry impregnation of polymeric foams, yielding a fired ceramic foam structure. These foam structures have high part-to-part standard deviation in flow rates (~25%) and have weak sections which can fragment into the melt. In contrast, periodic lattice filters (PLF’s) made by robocasting have a cross-hatched face-centered-cubic arrangement of rods.. As such, the robocast filters have high strength and may be easily tailored to offer a specific internal pore structure to control the flow rate and pressure drop across the filters. Standard deviation of flow rates among PLF’s are less than 1%. This paper describes the methodology of creating PLF’s as possible foam filter replacements.

null

['Khatua, Vivek', 'Gurumoorthy, B.', 'Ananthasuresh, G.K.']

2024-03-26T21:49:16Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124426', 'https://doi.org/10.26153/tsw/51034']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['fiber-reinforced polymer composite', 'photopolymerization', 'additive manufacturing']

Robot-aided selective embedding of a spatially steered fiber in polymer composite parts made using vat photopolymerization

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e806ce32-99c3-4478-9720-a4346472d767/download

University of Texas at Austin

Fiber-Reinforced Polymer Composite (FRPC) parts are predominantly laminates, shells, or surfaces wound with 2+D fiber patterns even after the emergence of additive manufacturing. Making FRPC parts with embedded continuous fibers in 3D is not reported previously even though topology optimization demonstrates that such designs are optimal. Earlier attempts in 3D fiber reinforcement include making parts with channels into which fibers are inserted or coextruding fiber with resin. In this work, A Vat-Photopolymerization Machine, and a process for concurrent embedding of spatially steered continuous fibers inside the matrix is developed. A single continuous fiber was embedded spatially using a robot to gradually steer the fiber as the part is built layer upon layer. An example of a fiber embedded along a helix in a cylindrical matrix is included in this work. Furthermore, a hinge effect was demonstrated when a fiber was embedded at a place that has substantial bending about the axis of the fiber.

null

['Baier, Christian', 'Weigold, Matthias']

2021-11-16T16:34:31Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90338', 'http://dx.doi.org/10.26153/tsw/17259']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['hybrid manufacturing', 'industrial robots', 'alloy 718', 'quality-loops', 'deep-drawing die']

Robot-Based Hybrid Manufacturing Process Chain

Conference paper

https://repositories.lib.utexas.edu//bitstreams/667ffb8a-28aa-4e07-8989-605e4ed8a9ba/download

University of Texas at Austin

The combination of additive and subtractive processes using an industrial robot in a hybrid production concept is an innovative approach in manufacturing technology. An improvement in the near net shape geometry production processes is achieved by using a wire-based laser metal deposition process with the added benefit of saving resources. Assisted by qualified CAM tools and an interposed laser line scanning, this process chain enables production of tool and dies, especially for automotive industry and manufacturing of parts made of nickelbased alloys for aerospace industry. This expands the workpiece material application range for robot-based milling. For the robot-machining processes, extended strategies in CAM path planning have been qualified focusing on increased machining-process quality. The system technology and sub-processes have been integrated into a robot-cell, enabling a hybrid part production process in a single workpiece clamping.

null

['Förster, Julia', 'Binder, Maximilian', 'Schlick, Georg', 'Seidel, Christian', 'Schilp, Johannes']

2023-01-27T14:14:33Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117336', 'http://dx.doi.org/10.26153/tsw/44217']

eng

2022 International Solid Freeform Fabrication Symposium

Open

powder bed fusion

Robot-guided Electrophotographic Powder Application System for Powder Bed Fusion of Metals by means of Laser Beam

Conference paper

https://repositories.lib.utexas.edu//bitstreams/975cb52f-299a-4afc-bfb2-adc6156d383c/download

null

Powder application remains amongst the core challenges in Powder bed based additive manufacturing. Current state of the art does hardly allow processing of powders with low flowability or the processing of multiple materials (multi-material) within one layer. In this paper, a powder application process based on electrophotography is presented to increase the flexibility of additive manufacturing processes using powder bed fusion of metals (PBF-LB/M) as specific reference. A novel conceptual design of an automated 6-axis robot- controlled prototype for electrophotographic powder application in a machine environment are shown. Experiments demonstrate single- and multi-layer powder depositions for the PBF-LB/M typical powder CW106C (CuCrZr1). A first qualitative comparison of the powder application process in the ambient media in atmospheric conditions and in an argon inert gas atmosphere is performed. With the automated powder application, the general inclusion in the PBF-LB/M cycle for multi-layer deposition and melting can be demonstrated.

null

['Solomon, E.', 'Yerazunis, W.S.']

2021-12-01T21:30:20Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90620', 'http://dx.doi.org/10.26153/tsw/17539']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['SLA 3D printing', 'robotic grippers', 'grippers', 'mechanical metamaterials']

Robotic Applications of Mechanical Metamaterials Produced Using SLA 3D Printing: Cthulhu-Morphic Grippers

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c0f69666-1e47-4a17-8017-db001a21ab5b/download

University of Texas at Austin

Presented in this paper is a 3D printed flexible robotic gripper which has three individual independently actuated tentacles, each with two sections, and a combined 12 degrees of freedom (DoF); produced through the creation of a mechanical metamaterial via SLA 3D printing. This gripper was built to improve upon existing soft robotic technologies by creating a highly versatile gripping device which can hold a wide variety of items. This gripper is capable of the fine motor control necessary to hold a pen or a small screw, the gross motor strength to hold a sledge hammer, and the grip span to hold a shop-vac air filter. Grip strengths and failure modes for various gripping configurations are measured. With an axial lift capacity well in excess of 100N, this gripper is strong enough to be useful in industrial applications. Potential industrial uses include warehouse or assembly line bin-picking and cobot operations.

null

['Shahan, David', 'Fulcher, Ben', 'Seepersad, Carolyn Conner']

2021-10-05T15:08:14Z

2011

Mechanical Engineering

null

['https://hdl.handle.net/2152/88389', 'http://dx.doi.org/10.26153/tsw/15328']

eng

2011 International Solid Freeform Fabrication Symposium

Open

['selective laser sintering', 'negative stiffness', 'vibration isolation', 'axially compressed beams']

Robust Design of Negative Stiffness Elements Fabricated by Selective Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9b50dd8c-c240-41ab-bd69-32d212c0986d/download

University of Texas at Austin

Constrained negative stiffness structures have been shown to possess desirable vibration isolation properties because of their ability to provide low dynamic stiffness, resulting in low transmissibility over a wide range of frequencies. In this research, selective laser sintering (SLS) is an integral part of a model-design-build-test process for investigating the vibration isolation capabilities of negative stiffness structures in the form of axially compressed beams. SLS provides geometric design freedom and rapid fabrication capabilities for validating dynamic models of structural behavior and guiding the design process toward iterative improvements. SLS also introduces some geometric and dimensional variability that can significantly degrade the performance of the structure. In this paper, an iterative model-design-build-test process for negative stiffness structures is described and presented with an analysis of the impact of SLS-induced imperfections on the results.

null

Chari, Jana K.

2018-05-03T18:14:43Z

1993

Mechanical Engineering

doi:10.15781/T2BK1768V

http://hdl.handle.net/2152/65050

eng

1993 International Solid Freeform Fabrication Symposium

Open

['IGES', 'Non-Uniform Rational B-Splines', 'NURBS', 'CAD file']

Robust Prototyping

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1a667fd0-3935-421d-8b77-0685b2edcb7a/download

null

This paper presents a new prototyping system consisting of a computer interface based on IGES standard to represent and path plan objects with precise curve and surface definitions and a laser-metal deposition process for the prototype fabrication. The advantage of using the Non-Uniform Rational B-Splines (NURBS) data instead of the traditional triangular data is that it requires fewer data conversions as most standard analytical shapes (like lines, conics, circles, planes and quadratic surfaces) as well as free form curves and surfaces are represented with one common underlying mathematical form. By addressing this issue of improved data representation on the CAD file front-end and an improved processing technique, this research will significantly impact the output of rapid prototyping with functional parts of improved tolerance and surface finish capabilities. A detailed description of the implementation of the computer interface on different hardware platforms and an outline of the fabrication process are presented. We conclude that NURBS interfacing technique is a robust mathematical technique and offers great potential for precise rapid prototyping.

null

['Wu, Sung-Heng', 'Joy, Ranjit', 'Tariq, Usman', 'Mahmood, Muhammad Arif', 'Liou, Frank']

2024-03-26T21:52:22Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124427', 'https://doi.org/10.26153/tsw/51035']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['direct energy deposition', 'melt pool', 'thermal distribution', 'in-situ monitoring', 'digital twin development']

Role of In-situ Monitoring Technique for Digital Twin Development using Direct Energy Deposition: Melt Pool Dynamics and Thermal Distribution

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b2e7fa74-0629-4028-a1fc-76b440535aa1/download

University of Texas at Austin

Direct energy deposition (DED) is a promising additive manufacturing technique that enables the fabrication of complex structures with excellent mechanical properties. The quality of the final product depends on several parameters, including melt pool dynamics and thermal distribution. For process monitoring and continuous improvement of digital twins, in-situ monitoring allows real-time tracking of these parameters, providing valuable data for process optimization. However, existing monitoring methods are limited in their accuracy due to emissivity issues. To address this challenge, an in-house visible spectrum camera has been proposed for real-time process monitoring via dual-wavelength technique. Based on the analyses, the area and thermal distribution inside the melt pool can be estimated accurately. The data from the camera can be integrated into a digital twin’s continuous improvement, providing efficiency, and reducing the manufacturing cost.

null

['Allen, J.', 'Cheng, J.', 'Hu, X.', 'Splitter, D.A.', 'Gussev, M.', 'Shyam, A.']

2021-12-07T19:02:15Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90758', 'http://dx.doi.org/10.26153/tsw/17677']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['additively manufactured interpenetrating composites', 'AMPICs', '316L', 'stainless steel', 'A356']

The Role of Interface in Additively Manufactured Interpenetrating Composites

Conference paper

https://repositories.lib.utexas.edu//bitstreams/eecf9aa7-458d-443a-8194-e04a2a779fcd/download

University of Texas at Austin

Additively Manufactured Interpenetrating Composites (AMIPCs) are a relatively new metal-metal chain composite in development for use in high energy absorption systems. In this system, reinforcing phase of additively manufactured continuous lattice configurations 316L austenitic stainless-steel is in melt infiltrated with a matrix phase of A356 aluminum-silicon casting alloy. Measurements and observations of this material system have shown that weakly bonded or open/porous interface between the reinforcement and matrix phases exhibits dramatically different mechanical properties of AMIPCs, which is not currently well understood. In this work, Finite Element Models (FEM) are used to model the effects of interfaces between the composite phases. Mechanical tensile tests measurements of various composite volume fractions and varying degrees of casting infiltration are also examined and used to show consistency with the FEM results. The outcome provides insight into material design criteria and performance predictions for new hybrid material systems with exceptional damage tolerance.

This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE).

null

['Rangarajan, Sriram', 'Qi, Gang', 'Banyopadhyay, Amit', 'Dai, Cheng', 'W. Han, Joon', 'Bhargava, Parag', 'Wu, Suxing', 'Safar, Ahmad', 'Danforth, Stephen. C.']

2018-12-05T20:16:17Z

1997

Mechanical Engineering

doi:10.15781/T2CV4CB90

http://hdl.handle.net/2152/71411

eng

1997 International Solid Freeform Fabrication Symposium

Open

['SFF', 'Printing/Inkjet Deposition']

The Role of Materials Processing Variables in the FDC Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/04e8c0dd-9fba-45d7-b0b0-b309d2d5371e/download

null

The Fused Deposition of Ceramics (FDC) is based on the commercially available Fused Deposition Modeling (IDMTM) technique developed by Stratasys Inc. The FDC process is being currently developed to make complex ceramic parts in an automated fashion. Although the current focus is on making SisN4 parts, this technique has been successfully used to make electroceramic (such as PZT) and metallic (such as stainless steel) parts. As feedstock for the IDC process, filaments loaded with 55 vol% GS-44 Si3N4 is being used. For the filament to be used in the IDC process, it must possess a unique combination of physical, rheological and mechanical properties. In this paper, we investigate the role played by some of the process variables on these properties. Our current processing sequence to make filaments is as follows - coating of powders with a surfactant, compounding the ceramic and binder, extrusion into filaments and finally treatment of filaments to achieve requisite properties. The study has resulted in improvements to the quality of the filament which can be used for automated FDC. The effect of moisture, agglomerates and filament aging on FDC will be discussed.

null

['Hauser, C.', 'Lewis, D. M.', 'Morris, K. F.', 'Broadbent, P. J', 'Zhao, X.', 'Clare, A. T.', 'Dunschen, M.']

2020-03-11T15:38:48Z

2008

Mechanical Engineering

null

['https://hdl.handle.net/2152/80255', 'http://dx.doi.org/10.26153/tsw/7274']

eng

2008 International Solid Freeform Fabrication Symposium

Open

['Direct Light Projection', 'DLP']

Rotational 3D Printing of Sensor Devices using Reactive Ink Chemistries

Conference paper

https://repositories.lib.utexas.edu//bitstreams/84a13a4b-7917-4980-87c1-5cdd1dca1e23/download

null

This paper charts progress in three key areas of a project supported by both UK government and UK industry to manufacture novel sensor devices using rotary 3D printing technology and innovative ink chemistries; (1) the development of an STL file slicing algorithm that returns constant Z height 2D contour data at a resolution that matches the given print head setup, allowing digital images to be generated of the correct size without the need for scaling; (2) the development of image transformation algorithms which allow images to be printed at higher resolutions using tilted print heads and; (3) the formulation of multi part reaction inks which combine and react on the substrate to form solid material layers with a finite thickness. A Direct Light Projection (DLP) technique demonstrated the robustness of the slice data by constructing fine detailed three dimensional test pieces which were comparable to identical parts built in an identical way from slice data obtained using commercial software. Material systems currently under investigation include plaster, stiff polyamides and epoxy polymers and conductive metallic’s. Early experimental results show conductivities of silver approaching 1.42x105 Siemens/m.

null

['Garrett, Alexis', 'Jaberi, Arian', 'Viotto, Auston', 'Yang, Ruiguo', 'Tamayol, Ali', 'Malshe, Ajay', 'Sealy, Michael P.']

2021-12-01T21:22:10Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90617', 'http://dx.doi.org/10.26153/tsw/17536']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['edible', 'polymer', 'cellular agriculture', 'photolithography']

Rotational Digital Light Processing for Edible Scaffold Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5210ba99-4105-47e2-9c97-710bce5edffe/download

University of Texas at Austin

A key hurdle to overcome in the development of alternative meat-based protein is the manipulation of mechanical or mastic properties of the 3D scaffolds. These properties influence the mouth feel of the product and must be tunable to achieve a variety of meat analogous textures. The goal of this research was to investigate a printing technology hypothesized to enable textural adjustment in alternative proteins. In pursuit of this goal, a novel digital light processing (DLP) printer with a rotational collector plate was developed to enable radially cured layers with the ability to incorporate multi-material composite structures. The purpose of this research was to quantify the effect of cured layer orientation on the bulk mechanical properties of (gelatin methacryloyl) GelMA scaffolds. In addition, current photocrosslinking systems do not emphasize the edibility of the materials used in the process. Tartrazine, an edible photo-absorber, was investigated in its use for improving print resolution during the crosslinking process.

null

['Richter, B.', 'Blanke, N.', 'Werner, C.', 'Vollertsen, F.', 'Pfefferkorn, F.E.']

2021-11-16T16:23:03Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90333', 'http://dx.doi.org/10.26153/tsw/17254']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['laser', 'polishing', 'additive manufacturing', 'surface analysis', 'identification', 'topography']

Roughness Parameters for Classification of As-Built and Laser Post-Processed Additive Manufactured Surfaces

Conference paper

https://repositories.lib.utexas.edu//bitstreams/dc9ade07-4515-4a3d-a3e9-8e4b395b474e/download

University of Texas at Austin

One of the challenges facing the industrial adoption of additively manufactured parts is the surface roughness on the as-built part. The surface roughness of parts is frequently characterized by metrics specified by international standards organizations. However, these standards list many surface metrics that can make it unclear which to use to best describe the surface. In this work, the ability of the various surface metrics to successfully classify the as-built and post-processed surfaces is studied using linear classification models. Laser polishing via remelting and manual grinding are the post-processing techniques used to smooth the as-built surface. The ability of the linear classifier to successfully categorize the various surfaces is demonstrated, and the various surface metrics are ranked according to the strength of their individual ability to classify the surfaces. This work promotes the method as a potential way to autonomously classify as-built and laser polished surfaces.

null

['Wang, Wanlong', 'Conley, James G.', 'Stoll, Henry W.', 'Jiang, Rui']

2019-03-06T18:07:30Z

1999

Mechanical Engineering

null

['https://hdl.handle.net/2152/73560', 'http://dx.doi.org/10.26153/tsw/702']

eng

1999 International Solid Freeform Fabrication Symposium

Open

['rapid tooling', 'process selection']

RP Process Selection for Rapid Tooling in Sand Casting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2838b9a2-4ace-499d-b19d-b4ff1f175d7f/download

null

The significant cycle-time improvements and geometrical capabilities of solid freeform fabrication systems have led to applications in sand casting industry for design verification and tooling. The time and cost effective deployment of rapid tooling processes using rapid prototyping technology has thus becoming an emerging area to be studied. To make full use of the advantages of rapid prototyping processes, the factors influencing the tooling approach must be identified and understood. This understanding is then used to develop a decision-making structure for RP process selection for rapid tooling in sand casting. In this manuscript we review our work in evaluating and building a framework for tooling process selection for sand casting

null

['Eschey, C.', 'Feldmann, S.', 'Zaeh, M.F.']

2021-10-04T21:55:05Z

8/17/11

Mechanical Engineering

null

['https://hdl.handle.net/2152/88362', 'http://dx.doi.org/10.26153/tsw/15301']

eng

2011 International Solid Freeform Fabrication Symposium

Open

['Additive Layer Manufacturing', 'rule-based FFD', 'Free-Form Deformation']

Rule-Based Free-Form Deformation for Additive Layer Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c9c971fb-5dca-4ad8-9b06-d0a4de946398/download

University of Texas at Austin

Additive Layer Manufacturing (ALM) provides manufacturing of nearly arbitrary geometries flexibly and economically. The part properties, which are reachable by state-of-the-art systems, are able to fulfill the customer requirements in terms of series and spare part production. Nevertheless, there still arise problems prohibiting the prevalent application of those techniques. The presented approach focuses on a rule-based Free-Form Deformation (FFD) for ALM. The machine is characterized by a set of rules, which is identified through observable properties extracted from precedent building processes. Adapting and applying the FFD algorithm, a pre-deformation of desired geometries based on exclusively geometric rules is achieved. Using an exclusively geometric deformation technique, CAD data is deformed before manufacturing to provide higher part quality by considering the unique characteristic of a machine.

null

['Schlienger, E', 'Griffith, M.', 'Oliver, M.', 'Romero, J.A.', 'Smugeresky, J.']

2019-02-19T20:09:05Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73443', 'http://dx.doi.org/10.26153/tsw/595']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['LENS', 'structure']

Sacrificial Materials for the Fabrication of Complex Geometries with LENS

Conference paper

https://repositories.lib.utexas.edu//bitstreams/41dccd2d-7a7c-4803-9638-5eec7489a81f/download

null

['Bzymek, Zbigniew M.', 'Ferreira, David', 'Marcus, Harris', 'Shaw, Leon L.']

2019-03-12T16:02:18Z

1999

Mechanical Engineering

null

['https://hdl.handle.net/2152/73592', 'http://dx.doi.org/10.26153/tsw/734']

eng

1999 International Solid Freeform Fabrication Symposium

Open

['SALVI', 'SALD']

SALD and SALVI Virtual Laboratory

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4fe0d0d8-8e81-4e49-a20c-72c546ae8303/download

null

This paper describes efforts to apply virtual manufacturing techniques to produce machine parts using Solid Freeform Fabrication (SFF). In particular, the work was done to develop a Virtual SFF Laboratory for the Selective Area Laser Deposition (S~D) and Selective Area Las~r Deposition Vapor Infl1tration (SALDVI) for the manufacture of machine parts and research on theIr characteristics, as well as for research on development of SAW and SALDVI technologies. It was the goal of the authors to supply the user with a tool to design a part, develop its three dimensional model, render it and observe its shape and dimensions. Except for research, laboratory is intended to be used for teaching principles of design and manufacturing of machine parts, as well as for delnonstrating SAW and SALVI processes to visitors. The Virtual Laboratory was developed on Silicon Graphics workstations. The Virtual Laboratory can create a multi-media, stereoscopic presentations of the SAW and SALVI processes in the Solid Freeform Fabrication Laboratory at the Institute of Material Science (IMS) at the University of Connecticut. The presentations can also be distributed through the Internet.

null

['Crocker, James E.', 'Wei, Haoyan', 'Shaw, Leon L.', 'Marcus, Harris L.']

2019-10-09T16:34:37Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76160', 'http://dx.doi.org/10.26153/tsw/3249']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Ceramic

SALDVI of SiC into Metal and Ceramic Powders

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d19f66b2-f033-4c7e-b953-0a2bf5c8a8b7/download

null

Selective Area Laser Deposition Vapor Infiltration (SALDVI) is the SFF technique using gas phase precursors to locally infiltrate a powder bed into a desired shape. Experiments were performed with a CO2 laser and the silicon carbide forming gas precursor Si(CH3)4. This paper will report on the microstructural aspects of SiC into a variety of metal and ceramic powders including Mo, SiC, ZrO2, and WC.

The authors acknowledge the support for this research by the Office of Naval Research (grant #N00014-95-1-0978).

null

['Crocker, James E.', 'Jakubenas, Kevin J.', 'Harrison, Shay', 'Shaw, Leon L.', 'Marcus, Harris L.']

2018-12-05T20:45:21Z

1997

Mechanical Engineering

doi:10.15781/T2GM8283H

http://hdl.handle.net/2152/71419

eng

1997 International Solid Freeform Fabrication Symposium

Open

['SALDVI', 'laser beam']

SALDVI Optimization for the Tetramethylsilane - Silicon Carbide System

Conference paper

https://repositories.lib.utexas.edu//bitstreams/31ca7457-4f38-4473-be14-7dda033ce02a/download

null

Selective Area Laser Deposition Vapor Infiltration (SALDVI) ofsilicon carbide powder infiltrated with silicon carbide deposited from tetramethylsilane (TMS) was studied. The effects of deposition time, temperature, and gas precursor pressure are discussed. The discussion centers on the efforts to properly balance these parameters to produce multi-layered shapes with structural integrity, particularly for use as the matrix material for shapes containing embedded devices. This includes optimizing scan speed, deposition temperature, and gas pressure to maximize infiltration to increase density and layer to layer bonding, and minimize excessive deposition to maintain critical dimensions. Initial powder properties are also optimized to minimize bulk motion in the powder bed during deposition, which was observed and identified as a mechanism that reduces inter-layer bonding.

null

['Kantareddy, S.N.R.', 'Roh, B.M.', 'Simpson, T.W.', 'Joshi, S.', 'Dickman, C.', 'Lehtihet, E.A.']

2021-11-01T21:23:09Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89758

eng

2016 International Solid Freeform Fabrication Symposium

Open

['large-scale lattice structures', 'metallic', 'metallic lattice structures', 'lattice structures', 'real-world example', 'oil', 'gas', 'additive manufacturing']

Saving Weight with Metallic Lattice Structures: Design Challenges with a Real-World Example

Conference paper

https://repositories.lib.utexas.edu//bitstreams/66829db6-684a-4e27-8ca5-1b91c692d5f1/download

University of Texas at Austin

Lattice structures are structurally efficient yet complex designs that enable high stiffness and reduce weight. While lattice structures are traditionally difficult to manufacture in metal with conventional fabrication processes, AM is a viable solution to manufacture such complex geometries to achieve lightweight designs. However, there is relatively little information available in the literature about designing large-scale lattice structures, particularly concerning computer-aided design tools, structural analysis, and post-processing for functional metallic components. In this study, we investigate and discuss these aspects in the context of a real-world problem for an oil and gas application. The lattice structure is designed and fabricated with IN 718 powder using an EOS M280 laser-based powder bed fusion system. A weight reduction of 42.4% is achieved while obtaining the desired mechanical performance. Results and challenges, particularly with the design workflow, are discussed along with future research directions.

null

['Chu, W.S.', 'Jung, B.S.', 'Ahn, H.']

2021-09-29T20:33:41Z

9/15/09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88217', 'http://dx.doi.org/10.26153/tsw/15158']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['drug delivery system', 'layer manufacturing', 'replication', 'direct deposition', 'scaffold fabrication', 'nano composite deposition system']

Scaffold Fabrication for Drug Delivery System Using Layered Manufacturing Methods

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9bdb90f3-ee4c-48db-b710-14ba92983d2c/download

University of Texas at Austin

To fabricate functional shape of drug delivery system (DDS), various processes are used. In this research, based on layered manufacturing, two different processes of 1) replication and 2) direct deposition were used to fabricate scaffold type implantable DDS. For replication process, hot embossing process for fabrication of patterned layers and bonding for construction of three-dimensional shape were used. As a direct deposition process, nano composite deposition system (NCDS) was used. Various scaffolds were fabricated with different filament size, pore size, and shape. It is observed that the scaffold type of implantable DDS is more stable than non-porous DDS through the in vivo test.

null

['Angrish, A.', 'Singh, S.', 'Shen, X.', 'Lee, Y.S.', 'Cohen, P.', 'Starly, B.']

2021-10-28T15:33:04Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89663

eng

2016 International Solid Freeform Fabrication Symposium

Open

['cybermanufacturing', 'process monitoring', 'NoSQL databases', 'networked additive manufacturing', 'mongoDB']

Scalable Linking of Slice Layer Information with Process Monitoring Data in Additive Manufacturing Machines

Conference paper

https://repositories.lib.utexas.edu//bitstreams/13443a0a-505b-4837-a2e2-7e137cb58288/download

University of Texas at Austin

In smart connected factories, manufacturing machines are capable of generating vast amounts of process data generated internally from within its control systems or from sensors coupled with the process. This streaming data must be stored and queried to perform data analytics or closed loop control to improve manufacturing processes. Currently, structured data schemas are ineffective in handling image and time-series data generated from additive manufacturing machines. In this paper, we propose an unstructured data schema through NoSQL document oriented database systems as an effective and scalable approach to capturing and storing real-time streaming data for process monitoring. In addition, we present an approach to linking in real-time, slice layer information and tag it with process related sensor data for performing fast, scalable queries either in real-time or post-fabrication. We have demonstrated our approach with two classes of additive manufacturing machines – Fused Deposition Modeling and Electron Beam Melting Systems from Makerbot and ARCAM respectively.

null

['Birnbaum, Andrew J.', 'Beuth, Jack L.', 'Sears, James W.']

2020-02-12T15:39:23Z

2004

Mechanical Engineering

null

['https://hdl.handle.net/2152/79941', 'http://dx.doi.org/10.26153/tsw/6967']

eng

2004 International Solid Freeform Fabrication Symposium

Open

Manufacturing Processes

Scaling Effects in Laser-Based Additive Manufacturing Processes

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6b091d2b-6b12-4275-acc8-e9a37ab66007/download

null

['Chung, Haseung', 'Das, Suman']

2019-10-24T17:30:09Z

2002

Mechanical Engineering

null

['https://hdl.handle.net/2152/77401', 'http://dx.doi.org/10.26153/tsw/4490']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Resolidification

Scaling Laws for Melting and Resolidification in Direct Selective Laser Sintering of Metals

Conference paper

https://repositories.lib.utexas.edu//bitstreams/959a0d09-b0ea-4b82-95f2-701e84c87a10/download

null

We present a one-dimensional model describing the physical mechanisms of heat transfer, melting and resolidification taking place during and after the interaction of a laser beam with a semi-infinite metal surface. The physical model describing this situation is based on the classical Stefan problem with appropriately chosen boundary conditions to reflect direct selective laser sintering of metals. A numerical model based on the finite volume method is developed to perform computations for different beam diameters, scan speeds, substrate temperatures and power input profiles. From the results of these computations, we derive relations for time to initiate melting, time to reach maximum melting depth, and total melt-resolidification time. The surface temperature histories for three different power input profiles are compared with approximate closed form solutions.

null

['Bermudez, Diego', 'Terrazas, Cesar A.', 'Morton, Phillip', 'Wicker, Ryan']

2021-11-01T23:04:23Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89794

eng

2017 International Solid Freeform Fabrication Symposium

Open

['scanning strategies', 'scanning', 'microstructure', 'Ti-6Al-4V', 'electron beam melting']

Scanning Strategies in Electron Beam Melting to Influence Microstructure Development

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0fc79706-a72f-4c10-97a2-710c048bdce1/download

University of Texas at Austin

Recent advances with the use of electron beam melting (EBM) additive manufacturing (AM) have indicated the ability to control the resultant microstructure based on control of the processing parameters. An Arcam A2 EBM system was utilized to control the size of the microstructure for Ti-6Al-4V components. The methodology employed allowed to refine the microstructure at selected regions of a part while maintaining a more typical acicular α+β microstructure in the rest of the components. This process was achieved by partitioning the layer data into two files that enabled different scanning conditions during fabrication. The first scan consisted of hatching of the component geometry (circle with dimensions of 15mm in diameter) excluding a center circle with dimensions of 1mm in diameter. Following the first scan, a pointwise melting for the center circle was completed. The strategy generated a finer structure in the center circle in comparison with the more regular sized microstructure in the rest of the build. Components built were sectioned and prepared into metallographic specimens that were observed through optical microscopy. The micrographs were used to measure the length and width of alpha laths.

null

['Wang, Zhaogui', 'Smith, Douglas E.']

2021-11-15T20:44:52Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90265', 'http://dx.doi.org/10.26153/tsw/17186']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['screw swirling', 'fiber orientation', 'elastic properties', 'large-scale additive manufacturing', 'LSAM']

Screw Swirling Effects on Fiber Orientation Distribution in Large-Scale Polymer Composite Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f635b33a-9cd4-4220-8b82-ac460da48df8/download

University of Texas at Austin

Large-Scale Additive Manufacturing (LSAM) polymer deposition employs a single screw extruder to melt and deliver the pelletized feedstock resulting in significantly higher flow rates as compared to conventional filament-extrusion AM processes. Single screw swirling motion in the melt flow during processing generates a unique pattern of flow-induced fiber alignment when fiber-filled polymer feedstock is processed. This paper investigates the effect of the single screw swirling motion on the fiber orientation and predicted elastic properties of a printed extrudate. A finite element extruder nozzle flow is created, where the extruder screw tip, the extrusion nozzle, and a short section of free extrudate compose the melt flow domain. The IRD-RSC fiber orientation diffusion model is applied to capture the slow orientation kinetics of short fibers in the concentrated fiber suspension. The results indicate that the swirling motion of the flow has a direct effect on predicted fiber orientation distribution and the associated averaged elastic properties in the extruded composite bead.

null

['Wood, Nathaniel', 'Hoelzle, David J.']

2021-11-16T16:09:44Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90328', 'http://dx.doi.org/10.26153/tsw/17249']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['temperature fields', 'closed-loop state', 'efficacy', 'powder bed fusion']

'Seeing' the Temperature Inside the Part During the Powder Bed Fusion Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/da1f2d28-c49b-4094-ae92-e26a99b14d57/download

University of Texas at Austin

Powder Bed Fusion (PBF) is a type of Additive Manufacturing (AM) technology that builds parts in a layer-by-layer fashion out of a bed of metal powder via the selective melting action of a laser or electron beam heat source. The technology has become widespread, however the demand is growing for closed loop process monitoring and control in PBF systems to replace the open loop architectures that exist today. This paper demonstrates the simulated efficacy of applying closed-loop state estimation to the problem of monitoring temperature fields within parts during the PBF build process. A simplified LTI model of PBF thermal physics with the properties of stability, controllability and observability is presented. An Ensemble Kalman Filter is applied to the model. The accuracy of this filters’ predictions are assessed in simulation studies of the temperature evolution of various test parts when subjected to simulated laser heat input. The significant result of this study is that the filter supplied predictions that were about 2.5x more accurate than the open loop model in these simulation studies.

null

['Morgan, Jacob P.', 'Morgan, John P. Jr.', 'Natale, Donald J.', 'Smith, Robert W.M.', 'Mitchell, Wesley F.', 'Dunbar, Alexander J.', 'Reutzel, Edward W.']

2021-11-03T22:32:53Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89951

eng

2017 International Solid Freeform Fabrication Symposium

Open

['process monitoring', 'high resolution imaging', 'sychronization', 'post-build 3D computed tomography', 'computed tomography', 'powder bed fusion additive manufacturing']

Selection and Installation of High Resolution Imaging to Monitor the PBFAM Process, and Synchronization to Post-Build 3D Computed Tomography

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0bd26817-21dc-4580-b896-6d41a23ccfc1/download

University of Texas at Austin

Industrial applications of PBFAM continue to expand, and there is a growing interest in the use of sensors to monitor the build process. Sensor data collected during the build process provides insight into process physics and may also lead to a reduction in overall fabrication time and cost by offering an alternative to extensive post-build nondestructive inspection for quality control. Ultimately, sensor data may serve as feedback for real-time control systems that automatically repair flaws before they are buried by subsequent layers. In this work, high resolution images are explored as a means of monitoring the PBFAM build process inside a 3D Systems ProX320. Key design considerations for camera selection and integration are discussed. Methods and algorithms are developed to calibrate and map layer-wise imagery to laser scan vectors. Images are stacked and exported to standardized 3D data formats to enable easy inspection and comparison to post-build 3D computed tomography (CT) volumes.

null

['Harris, Russ', 'Hopkinson, Neil', 'Dickens, Phill', 'Hague, Richard']

2019-09-23T17:08:07Z

2000

Mechanical Engineering

null

['https://hdl.handle.net/2152/75975', 'http://dx.doi.org/10.26153/tsw/3074']

eng

2000 International Solid Freeform Fabrication Symposium

Open

Mould

The Selection of Mould Design Variables in Direct Stereolithography Injection Mould Tooling 478

Conference paper

https://repositories.lib.utexas.edu//bitstreams/86a6e782-15ae-4039-9d14-3cb54b0b62b9/download

null

The introduction of rapid prototyping has allowed engineers and designers to generate physical models of required parts very early on in the design and development phase. Further to this the use of stereolithography (SL) cavities as a rapid tooling method has allowed plastic prototype parts to be produced in their most common production manner; by injection moulding. The process is best suited to small production runs where the high costs of conventionally machined tooling is prohibitive. One of the major drawbacks of the SL injection moulding process is the susceptibility of the tools to premature failure. SL tools may break under the force exerted by part ejection when the friction between a moulding and a core is greater than the tensile strength of the core resulting in tensile failure. Very few justified recommendations exist concerning the choice of mould design variables that can lower the part ejection force experienced and reduce the risk of SL tool failure. This research investigates the ejection forces resulting from injection moulding polypropylene (PP) and acrylonitrile-butadiene-styrene (ABS) parts from SL tools which are identical in all respects except for their build layer thickness and incorporated draft angles. This work attempts to identify appropriate evidence for recommendations with respect to these design variables and SL injection moulding. The results show that adjustment of draft angle results in a change of part ejection force as a reasonably linear relationship. An adjustment of the build layer thickness results in a change in part ejection force as a more non-linear relationship. The adjustment of build layer thickness had a greater effect on ejection force than the adjustment of draft angle. In both cases greater ejection forces were experienced by ABS parts as compared to PP parts. The results also show that the surface roughness of all tools remains unchanged after moulding a number of parts in both polymers.

null

['Thissell, W.Richards', 'Zong, Guisheng', 'Tompkins, James', 'Birmingham, Britton R.', 'Marcus, Harris L.']

2018-04-17T18:48:44Z

1991

Mechanical Engineering

doi:10.15781/T26Q1T08B

http://hdl.handle.net/2152/64352

eng

1991 International Solid Freeform Fabrication Symposium

Open

['Center for Materials Science and Engineering', 'SALD', 'pyrolytic', 'photolytic']

Selective Area Laser Deposition - A Method of Solid Freeform Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/bce07d25-a366-4687-bc49-6e5373f6c1c4/download

null

['Weiss, Clayton M.', 'Marcus, Harris L.']

2021-10-05T18:41:35Z

8/22/12

Mechanical Engineering

null

['https://hdl.handle.net/2152/88403', 'http://dx.doi.org/10.26153/tsw/15342']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['ceramic joining', 'ceramic manufacturing', 'selective area laser deposition', 'silicon nitride']

Selective Area Laser Deposition for Silicon Nitride Joining

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4d23463e-4ce7-4954-a017-437676ec2429/download

University of Texas at Austin

Ceramic joining is a difficult step in ceramic manufacturing. Joining ceramics, in a chemically homogeneous way, can be performed through the repurposing of an additive manufacturing technique involving local deposition of ceramics from the gas phase. Selective area laser deposition uses a gas phase precursor environment and a laser heat source to form ceramic deposits. These deposits can be positioned with great spatial resolution; as such, it is possible to form the joint with the ceramic material to create a monolithic structure. Silicon nitride is explored as a joining material for silicon nitride work pieces. The experimental conditions are described and the joint formation is characterized.

null

['Birmingham, B.R.', 'Zong, G.', 'Tompkins, J.V.', 'Marcus, H.L.']

2018-04-17T19:42:38Z

1991

Mechanical Engineering

doi:10.15781/T2K06XJ0Z

http://hdl.handle.net/2152/64358

eng

1991 International Solid Freeform Fabrication Symposium

Open

['Center for Materials Science and Engineering', 'SALD', 'SFF']

Selective Area Laser Deposition from Acetylene and Methane to Increase Deposition Control

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5ed717c5-3520-47eb-8982-7a664ec4ae4d/download

null

Selective area laser deposition (SALD) has been used to deposit carbon from acetylene. Working at the relatively high pressures required to produce high deposition rates can result in explosive uncontrollable growth. Pr~vious computational modeling indicates that the energy released from the exothermic decomposition of acetylene to carbon may be responsible for this behaviour[l]. Since methane decomposes endothermically to form carbon over certain temperatures, it is possible that methane addition to the process may help control the deposition rate. The purpose of this paper is to describe SALD experiments that were performed using various partial pressures of acetylene and methane as precursor in order to determine if combining an endothermic and an exothermic reaction effects the control of the SALD process.

null

['Jakubenas, Kevin', 'Marcus, H.L.']

2018-11-08T15:13:16Z

1995

Mechanical Engineering

doi:10.15781/T27D2QT0K

http://hdl.handle.net/2152/69885

eng

1995 International Solid Freeform Fabrication Symposium

Open

['SALD', 'deposition experiments', 'vapor deposition']

Selective Area Laser Deposition from Titanium Tetrachloride

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b4aed227-2475-4a49-ab38-c7360b0298fc/download

null

Selective Area Laser Deposition (SALD) has demonstrated the ability to deposit controlled shapes of silicon carbide and silicon nitride by using a laser beam to decompose a precursor gas. The goal of the work here is to include titanium among the list of SALD materials, although this goal has not yet been reached. This paper describes the selection of precursors and the results of some SALD experiments using the first precursor explored, titanium tetrachloride. The results of precursor gas mixture, pressure, and laser power on deposition composition and rates are discussed.

null

['Weiss, Clayton', 'Marcus, Harris']

2021-10-11T21:12:42Z

8/16/13

Mechanical Engineering

null

['https://hdl.handle.net/2152/88643', 'http://dx.doi.org/10.26153/tsw/15577']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['selective area laser deposition', 'monolithic joint', 'aluminum oxide']

Selective Area Laser Deposition Joining of Aluminum Oxide

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a2e7e1f6-321b-4507-9271-7f0a5c0993b9/download

University of Texas at Austin

Selective area laser deposition (SALD) is a chemical vapor deposition technique used to deposit ceramic material. The technique allows localized deposition in the area of the laser spot; complex depositions can be achieved through the use of a computer control program. It is possible to free form fabricate arbitrary shapes. In particular by defining the space between two work pieces as the envelope for deposition, it is possible to form a monolithic joint. The use of a trimethylaluminum and diethyl ether precursor system is explored as a means of depositing aluminum oxide. The alumina is used as joint fill material for alumina SALD joining.

null

Tompkins, James V.

2018-05-03T19:57:09Z

1993

Mechanical Engineering

doi:10.15781/T23X84367

http://hdl.handle.net/2152/65075

null

1993 International Solid Freeform Fabrication Symposium

Open

['selective area laser deposition', 'SALD', 'Center for Materials Science and Engineering']

Selective Area Laser Deposition of Silicon Carbide

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4bbe84c1-3bd9-4590-8b80-96a9c650bfa7/download

null

['Schwerdtfeger, Jan', 'Heinl, Peter', 'Singer, Robert F.', 'Körner, Carolin']

2021-09-29T18:06:51Z

9/18/09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88204', 'http://dx.doi.org/10.26153/tsw/15145']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['auxetic cellular structures', 'titanium alloys', 'Selective Electron Beam Melting']

Selective Electron Beam Melting: A new Way to Auxetic Cellular Structures

Conference paper

https://repositories.lib.utexas.edu//bitstreams/69e42821-2ca1-45c9-ad2c-f41d26843203/download

null

This paper is concerned with the build up and characterisation of well defined auxetic structures from Titanium alloys through Selective Electron Beam Melting (SEBM).The negative Poisson’s ratio of auxetic structures make them interesting candidates for a wide range of applications (e.g. joining of dissimilar materials). Up to date auxetic cellulars have mainly been produced through volumetric compression of conventional foams. However, by using SEBM we are able to produce structures of any geometry in a well defined manner. This opens an almost limitless field for new cellular auxetics and the tuning of their properties. In the following we will introduce a simple self designed auxetic structure and show first results for the mechanical characterisation of that structure.

null

['Baumers, M.', 'Tuck, C.', 'Hague, R.']

2021-10-19T18:02:13Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89312

eng

2014 International Solid Freeform Fabrication Symposium

Open

['Selective Heat Sintering', 'Laser Sintering', 'deposition rate', 'energy consumption', 'cost']

Selective Heat Sintering Versus Laser Sintering: Comparison of Deposition Rate, Process Energy Consumption and Cost Performance

Conference paper

https://repositories.lib.utexas.edu//bitstreams/fc86ad6e-89c0-45d4-b551-8ddabb0aa426/download

University of Texas at Austin

The Selective Heat Sintering (SHS) process has become available as a low cost alternative to Laser Sintering (LS) for the additive deposition of polymer objects. While both processes belong to the powder bed fusion variant of Additive Manufacturing (AM) technology, their operating principles vary significantly: SHS employs a thermal print head to selectively fuse material powder, whereas the LS approach utilizes a laser beam coupled with a galvanometer. Based on a series of build experiments, this research compares these technology variants along three dimensions of process efficiency: deposition rate (measured in cm³/h), specific process energy consumption (MJ/kg) and specific cost ($/cm³). To ensure that both platforms are assessed under the condition of efficient technology utilization, an automatic build volume packing algorithm is employed to configure a subset of build experiments. Beyond reporting absolute and relative process performance, this paper additionally investigates how sensitive the compared processes are to a variation in the degree of capacity utilization and discusses the application of different levels of indirect cost in models of low cost AM.

null

['Wimpenny, David Ian', 'Banerjee, Soumya']

2020-03-05T20:30:58Z

9/14/06

Mechanical Engineering

null

['https://hdl.handle.net/2152/80161', 'http://dx.doi.org/10.26153/tsw/7182']

eng

2006 International Solid Freeform Fabrication Symposium

Open

rapid prototyping

Selective Infrared Sintering of Polymeric Powders using Radiant IR Heating & Ink Jet Printing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4df8c43b-9dd8-4289-9ed0-e5279168da3a/download

null

Established methods of rapid prototyping by sintering polymeric powders have predominantly focused on the use of lasers to selectively heat the polymeric particles together to form fused layers. Although effective, this route requires the laser to draw in the entire cross section of the slice and this limits the speed of the process, particularly for the production of thick walled parts. The use of IR radiant lamps to fuse an entire layer simultaneously has been explored by several groups and is now the basis of at least one commercially available process (Speed Part). An alternative route, developed by the Rapid Prototyping & Manufacturing Group (RPMG) at DeMonfort University, where areas of the powder bed are selectively treated to promote absorption by particular IR radiation will be described in this paper. The advantages of this approach and the limitations which must be overcome through further research will be fully discussed.

null

['El-Desouky, A.', 'Read, A.L.', 'Bardet, P.M.', 'Andre, M.', 'LeBlanc, S.']

2021-10-21T15:41:29Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89400

eng

2015 International Solid Freeform Fabrication Symposium

Open

['Selective Laser Melting', 'thermoelectric material', 'bismuth telluride']

Selective Laser Melting of a Bismuth Telluride Thermoelectric Materials

Conference paper

https://repositories.lib.utexas.edu//bitstreams/fd699b9c-ee55-4430-a7e5-d0ddd2e57e21/download

University of Texas at Austin

Selective Laser Melting (SLM) technology is a rapidly growing solid freeform fabrication tool because it is cost effective, reduces production time of complex shapes, and accommodates a range of material systems such as metals, ceramics, polymers, intermetallics and composites. This work presents the first-ever results for SLM performed on a semiconducting thermoelectric material, bismuth telluride (Bi2Te3), using a Nd:YLF pulsed laser. The evolution of the localized melt lines formed under different processing parameters such as laser power and scan speed was investigated. Melt lines were evident on the top surface of the powder compacts under all investigated processing conditions. However, cross-sections taken across the melt lines revealed material removal at the irradiation site with minimum consolidation in the subsurface. Experimental results demonstrate that it is possible to laser melt Bi2Te3 powder, which enables new possibilities in additive manufacturing of 3D semiconductor thermoelectric components.

null

['Zhang, Jinliang', 'Song, Bo', 'Zhang, Lei', 'Liu, Jie', 'Shi, Yusheng']

2021-11-10T22:59:32Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90202', 'http://dx.doi.org/10.26153/tsw/17123']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', 'aluminum alloys', 'microstructure', 'densification', 'mechanical property']

Selective Laser Melting of Al6061 Alloy: Processing, Microstructure, and Mechanical Properties

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f3b80e0f-18b7-47a6-aeba-4b336a655c5a/download

University of Texas at Austin

Selective laser melting (SLM) is considered as one of the most promising additive manufacturing (AM) technologies. Aluminum alloy is of wide application potentiality due to their high specific strength and heat resistance. In this study, Al6061 alloy was prepared via selective laser melting (SLM) and densification, microstructure and properties were investigated systematically. It was found that process parameters including laser power and scanning rate have a great effect on the forming quality and the porosity of the samples. The α-Al phase is observed in XRD results and (200) is the preferable orientations of α-Al crystal in the SLM process. The microstructure can be divided into three areas: fine grained area, coarse grained area and heat affected area. As for the nanohardness, with the increase of laser power, the elastic modulus and hardness of SLM aluminum alloy show the trend of increasing first and then decreasing, and with the increase of scanning speed, the hardness of SLMed aluminum alloy is gradually reduced. With the increasing laser power and decreasing scanning rate, the elastic modulus and hardness of the samples increased first and then decreased.

null

['Hu, Zhiheng', 'Zhu, Haihong', 'Qi, Ting', 'Zhang, Hu', 'Zhang, Changchun', 'Zeng, Xiaoyan']

2021-11-02T19:33:58Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89876

eng

2017 International Solid Freeform Fabrication Symposium

Open

['AlCu5MnCdVA', 'selective laser melting', 'formability', 'microstructure', 'mechanical property']

Selective Laser Melting of AlCu5MnCdVA: Formability, Microstructure and Mechanical Properties

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4379c31f-c8c1-4073-960f-f5cd8e878323/download

University of Texas at Austin

Selective laser melting (SLM) is an additive manufacture (AM) technique that uses powders to fabricate 3D parts directly. Many researchers are interested in the formability and properties of the established materials manufactured by SLM. The proposed paper illustrates the formability, microstructure and mechanical properties of selective laser melted AlCu5MnCdVA. In this research, crack-free samples with relative density of nearly 100% were produced by SLM from gas atomized powders. Typical columnar crystal and inhomogeneous element distribution were obtained. The mechanical properties were test for the SLMed samples.

null

['Vandenbroucke, Ben', 'Kruth, Jean-Pierre']

2020-02-27T20:50:33Z

9/14/06

Mechanical Engineering

null

['https://hdl.handle.net/2152/80105', 'http://dx.doi.org/10.26153/tsw/7126']

eng

2006 International Solid Freeform Fabrication Symposium

Open

Rapid Prototyping

Selective Laser Melting of Biocompatible Metals for Rapid Manufacturing of Medical Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c1f9951a-7f6f-4285-a09c-adf18b42d611/download

null

In recent years, digitizing and automation have gained an important place in fabrication of medical parts. Rapid Manufacturing could be very suitable for medical applications due to their complex geometry, low volume and strong individualization. The presented study investigates the possibility to produce medical or dental parts by Selective Laser Melting (SLM). The SLMprocess is optimized and fully characterized for two biocompatible metal alloys: TiAl6V4 and CoCrMo. This paper reports on mechanical and chemical properties and discusses geometrical feasibility including accuracy and surface roughness. The potential of SLM as medical manufacturing technique is proved by a developed procedure to fabricate frameworks for complex dental prostheses.

null

['Mumtaz, K. A.', 'Hopkinson, N.']

2020-03-10T17:45:42Z

9/10/08

Mechanical Engineering

null

['https://hdl.handle.net/2152/80241', 'http://dx.doi.org/10.26153/tsw/7260']

eng

2008 International Solid Freeform Fabrication Symposium

Open

Selective Laser Melting

Selective Laser Melting of Inconel 625 using Pulse Shaping

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c5c6a417-dc08-4f72-80b3-a70a45f72246/download

null

Pulse shaping is a technique used to temporally distribute energy within a single laser pulse. This allows the user to have an added degree of control over the heat delivered to the laser material interaction zone. Pulses that induce a gradual heating or a prolonged cooling effect can be generated with peak power/pulse energy combinations specifically tailored to control melt pool properties and eventual part formation. This investigation used a pulsed 550W Nd:YAG laser to melt 0.1mm layers of Inconel 625 from a powder bed. Initially a set of optimization experiments were completed to develop laser parameters that enabled the production of thin wall parts with low top and side surface roughness. Thin wall parts were then built using pulse shape control employing a variety of pulse energy distributions. Parts built with and without pulse shape control were measured for width, top and side surface roughness. The effectiveness of pulse shaping control is discussed including potential benefits for use within Selective Laser Melting (SLM).

null

['Wiria, Florencia Edith', 'Sing, Swee Leong', 'Yeong, Wai Yee']

2021-11-04T21:08:36Z

2017

Mechanical Engineering

null

['https://hdl.handle.net/2152/90029', 'http://dx.doi.org/10.26153/16950']

eng

2017 International Solid Freeform Fabrication Symposium

Open

['lattice structures', 'titanium-tantalum alloy', 'orthopedic biomaterial', 'biomaterial', 'selective laser melting']

Selective Laser Melting of Novel Titanium-Tantalum Alloy as Orthopedic Biomaterial

Conference paper

https://repositories.lib.utexas.edu//bitstreams/fa4256e0-b6dd-4453-9381-12b6ec4da953/download

University of Texas at Austin

Selective laser melting (SLM) is an additive manufacturing (AM) technique that is capable of fabricating complex functional three-dimensional (3D) metal parts directly from the complete melting and fusion of powders. As a powder bed fusion technology, SLM has the potential to expand its material library by forming alloys that were previously difficult to achieve by using metal powder mixtures that can be customized according to the application requirements. Titanium-tantalum (TiTa) is a material that has potential uses in biomedical applications due to its high strength-to-modulus ratio. However, it is still not widely used because it is difficult to obtain. SLM is chosen as the method to form this alloy due to its versatility in processing metallic materials and good results obtained from commercially pure titanium (cpTi). Preliminary studies using cpTi lattice structures designed for biomedical applications were carried out. This research aims to develop TiTa as a material to be potentially used in biomedical field by investigating its processing window, resulting microstructure, and mechanical properties.

null

['Stoffregen, H.A.', 'Fischer, J.', 'Siedelhofer, C.', 'Abele, E.']

2021-10-05T14:59:28Z

8/17/11

Mechanical Engineering

null

['https://hdl.handle.net/2152/88387', 'http://dx.doi.org/10.26153/tsw/15326']

eng

2011 International Solid Freeform Fabrication Symposium

Open

['porous structures', 'selective laser melting', 'lattice structures', 'Center of Smart Interfaces', 'Institute of Production Management, Technology and Machine Tools']

Selective Laser Melting of Porous Structures

Conference paper

https://repositories.lib.utexas.edu//bitstreams/63f90e73-f3a7-4fac-a60e-45ed3cffe11b/download

University of Texas at Austin

Within the Center of Smart Interfaces “Understanding and Designing Fluid Boundaries”, a German Excellence Initiative, the Institute of Production Management, Technology and Machine Tools examines the manufacturing of porous structures by using selective laser melting (SLM). In this paper two different strategies are presented in order to obtain porosity: One strategy is to manufacture geometrically defined lattice structures. SLM allows here complex geometries that cannot be manufactured by conventional technologies to be built. The second approach is to manufacture geometrically undefined porosity by a specific modification of exposure parameters. The SLM generated porous structures are investigated with respect to the heat and mass transfer. The research focus is to increase the efficiency of spraycooling effects and the manipulation of the Leidenfrost point.

null

['Yap, C.Y.', 'Du, Z.', 'Chua, C.K.', 'Dong, Z.L.']

2021-10-27T21:45:15Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89625

eng

2016 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', 'tin']

Selective Laser Melting of Pure Tin: Microstructure Study

Conference paper

https://repositories.lib.utexas.edu//bitstreams/aeddd3a5-0443-4eda-861c-1cc0f07cfbc2/download

University of Texas at Austin

Selective Laser Melting (SLM) of pure tin was examined and 3D samples were successfully fabricated. High relative density of 99.9 % was achieved. Microstructure study was carried out via a combination of X-ray diffraction (XRD), light microscopy (LOM) and electron backscatter diffraction (EBSD). Under LOM, columnar structures, some spanning the entire height of the sample, are observed in the vertical plane. This study also examines the variation of relative density against process parameters such as hatch spacing and the input volumetric energy density for the SLM of tin.

null

['Badrinarayan, B.', 'Barlow, J.W.']

2018-04-17T18:28:08Z

1991

Mechanical Engineering

doi:10.15781/T2057D90F

http://hdl.handle.net/2152/64346

eng

1991 International Solid Freeform Fabrication Symposium

Open

['Department of Chemical Engineering', 'laser sintering', 'copper', 'polymer', 'part density', 'dwell time', 'shrinkage']

Selective Laser of a Copper-PMMA System

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7b3361c1-4e59-411e-b225-5c6bea5d9f39/download

null

The Selective Laser Sintering process was used to manufacture green copper parts from a copper-polymer mixture. PMMA was used as the polymer binder for the metal. The green part was fired in a furnace under reducing conditions to obtain a pure metal part. The metal-polymer system and the conditions used to make parts are described in this paper. The effect of laser parameters and particle sizes on part density are also discussed. Keywords: laser sintering, copper, polymer, part density, dwell time, shrinkage.

null

['Jakubenas, K.', 'Marcus, H.L.']

2018-10-03T18:25:12Z

1994

Mechanical Engineering

doi:10.15781/T2T14V796

http://hdl.handle.net/2152/68671

eng

1994 International Solid Freeform Fabrication Symposium

Open

['selective laser pyrolysis', 'polycarbosilane', 'polymeric precursor']

Selective Laser Pyrolysis for Solid Free-FonTI Fabrication of Silicon Carbide

Conference paper

https://repositories.lib.utexas.edu//bitstreams/aeec8e3f-b9c8-4324-bd39-78835150becb/download

null

Selective laser pYrolysis rapidly decomposes a polymeric precursor to form a cohesive ceramic shape. The considerable shrinkage and porosity during pYrolysis of pure precursor can be modified by the addition of either inert or reactive fillers. With polycarbosilane as the polymeric precursor, the process forms shapes of ~-SiC and, by using fillers, composites of ~-SiC/Al4C3/Al, ~-SiC/TiC/Ti, and ~-SiC/ZrC/Zr. The technique offers some potential for ceramic shapes with custom designed composition and microstructure including nanometer grain size.

null

['Ku, C.W.', 'Gibson, I.', 'Cheung, W.L.']

2019-10-22T18:12:35Z

2002

Mechanical Engineering

null

['https://hdl.handle.net/2152/76332', 'http://dx.doi.org/10.26153/tsw/3421']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Polystyrene

Selective Laser Sintered CastForm™ Polystyrene with Controlled Porosity and Its Infiltration Characteristics by Red Wax

Conference paper

https://repositories.lib.utexas.edu//bitstreams/063db525-e2a4-4d91-b8cd-545ddd8655f0/download

null

This paper focuses on the manufacture of polymer-based components with controlled porosity using selective laser sintering (SLS) and on their infiltration characteristics by red wax. CastFormTM Polystyrene (CF) samples with various densities were created by controlling the laser energy density. Wax was then infiltrated into the sintered specimens at around 638C to 648C. The microstructures of the sintered specimens were examined using scanning electron microscopy. The physical density was found to increase with increasing energy density and it reached a maximum at energy density of 0.11 J/mm2 . The infiltration rate and mass of infiltrant absorbed in a given time were found to increase with increasing porosity. However, none of the specimens could be fully infiltrated and about 10 – 20 % of porosity still remained regardless of energy density used for the sintering process. Finally, the potential applications of SLS parts with controlled porosity will be discussed.

This paper describes a project funded by the Research Grants Council on ‘Functionally graded part fabrication based on the SLS process’.

null

['Kolan, Krishna C.R.', 'Doiphode, Nikhil D.', 'Leu, Ming C.']

2021-10-01T00:35:18Z

2010

Mechanical Engineering

null

['https://hdl.handle.net/2152/88311', 'http://dx.doi.org/10.26153/tsw/15252']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['13-93 glass', 'synthetic scaffolds', 'additive manufacturing', 'selective laser sintering', 'freeze extrusion fabrication', 'bone repair']

Selective Laser Sintering and Freeze Extrusion Fabrication of Scaffolds for Bone Repair Using 13-93 Bioactive Glass: A Comparison

Conference paper

https://repositories.lib.utexas.edu//bitstreams/918ab21d-d139-4116-aa36-35423fb7b575/download

null

13-93 glass is a third-generation bioactive material which accelerates the bone’s natural ability to heal by itself through bonding with surrounding tissues. It is an important requirement for synthetic scaffolds to maintain their bioactivity and mechanical strength with a porous internal architecture comparable to that of a human bone. Additive manufacturing technologies provide a better control over design and fabrication of porous structures than conventional methods. In this paper, we discuss and compare some of the common aspects in the scaffold fabrication using two such processes, viz. selective laser sintering (SLS) and freeze extrusion fabrication (FEF). Scaffolds fabricated using each process were structurally characterized and microstructure analysis was performed to study process differences. Compressive strength higher than that of human trabecular bone was achieved using SLS process and strength almost comparable to that of human cortical bone was achieved using FEF process.

null

['Griffin, E. Alair', 'McMillin, Scott']

2018-10-03T19:40:18Z

1995

Mechanical Engineering

doi:10.15781/T24B2XQ22

http://hdl.handle.net/2152/68684

eng

1995 International Solid Freeform Fabrication Symposium

Open

['solid freeform fabrication', 'CAD', 'LPE']

Selective Laser Sintering and Fused Deposition Modeling Processes For Functional Ceramic Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/50b5afb3-1483-4fd4-be6d-17fe41b01a18/download

null

A variety ofsolid freeform fabrication (SFF) techniques have been developed to produce prototype parts directly from a computer-aided drawing (CAD) without any hard tooling, dies or molds [1]. Most ofthese techniques use polymer, wax, or paper materials to produce the parts. These techniques, with SOlne lnodifications, can be used to rapidly prototype functional ceramic parts. Once developed, these techniques could also be used to manufacture small quantities of ceralnic parts on a just-in-time basis. Fabrication using conventional techniques is a costly, titne-consuming, and inflexible process when a few ceramic prototypes or when small quantities of parts are needed. Solid freeform fabrication of ceralnic parts offers numerous advantages over conventional processing. Prototypes can be prepared rapidly and cost-effectively. Design changes can be made easily and inexpensively. Larger nUlnber of design options can be investigated. Parts can be designed and engineered to take advantage ofthe stronger properties of ceramics, while minimizing the weaker ones. Typically, ceramic parts are made using an existing design, regardless ofthe material used for the original part. The ability to rapidly prototype a ceralnic component will contribute to concurrent engineering, a popular design process being used today. Lone Peak Engineering (LPE) is developing three SFF processes for ceramics based on: 1. Selective Laser Sintering (SLS) 2. Fused Deposition Modeling (FDM) 3. Lalninated Object Manufacturing (LOM™) TMLOM is a registered trademark of Helisys, Inc. Torrance, CA 25 This paper discusses preliminary results with the SLS and FDM processes. LPE's ceramic LOM based process has been reported at this symposium [2] as well as at other meetings and in different publications [3].

null

['Vallabhajosyula, Phani', 'Bourell, David L.']

2020-03-11T14:33:48Z

9/10/08

Mechanical Engineering

null

['https://hdl.handle.net/2152/80244', 'http://dx.doi.org/10.26153/tsw/7263']

eng

2008 International Solid Freeform Fabrication Symposium

Open

selective laser sintering

Selective Laser Sintering and Post Processing of Fully Ferrous Components

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b917eb19-58d4-41b2-91db-a74eb787bd4f/download

null

Commercially available steel for indirect SLS (LaserFormtm A6 tool steel) is normally post-process infiltrated with a copper-based material. While such parts have high thermal conductivity necessary for short- and medium-run injection molding dies, they are weakened by the second phase with limited high temperature stability. This paper deals with a modification to the commercial process whereby a low-melting-point cast iron is substituted for the copper alloy infiltrant. A predictive model is presented that describes the part equilibrium solid fraction at the infiltration temperature as a function of the green density and infiltration temperature. In an experimental study, green parts were fabricated using LaserFormtm A6 tool steel powder. They were then heated in vacuum to drive off the binder and infiltrated with ASTM A532 white cast iron. During infiltration, an equilibrium state is established between the solid SLS steel part and liquid cast iron associated primarily with carbon diffusion from the cast iron into the tool steel. The equilibrium state is governed by the carbon content of the steel and cast iron, the relative density of the steel part prior to infiltration and the infiltration temperature. In some cases guided by Ashby densification maps, pre-sintering of the tool steel green part was performed to increase the initial relative density of the solid metal.

null

['Subramanian, Kamatchi', 'Zong, Guisheng', 'Marcus, H.L.']

2018-04-19T16:09:12Z

1992

Mechanical Engineering

doi:10.15781/T20000H37

http://hdl.handle.net/2152/64378

eng

1992 International Solid Freeform Fabrication Symposium

Open

['Center for Materials Science and Engineering', 'SLS', 'SLRS']

Selective Laser Sintering and Reaction Sintering of Ceramic Composites

Conference paper

https://repositories.lib.utexas.edu//bitstreams/bf68c35a-443a-411f-b067-28da4f713b36/download

null

Selective Laser Sintering and Reaction Sintering (SLS and SLRS) are used as methods of forming composites and preforms. Al20jAI and SiC/AI were studied as model systems. Ceramic and metallic powders are mixed and locally sintered using SLS and SLRS. Post processing heat treatment was also employed. Wettability and residual stress aspects of this process are discussed.

null

Kent, Nutt

2018-04-17T16:36:36Z

1991

Mechanical Engineering

doi:10.15781/T29K4694P

http://hdl.handle.net/2152/64328

eng

1991 International Solid Freeform Fabrication Symposium

Open

['CAD', 'CAE', 'DFM', 'DFA']

Selective Laser Sintering as a Rapid Prototyping and Manufacturing Technique

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b576cca0-c8be-4a01-96fb-ffb28daf7043/download

null

With accelerating growth and competition in today's global marketplace, manufacturers face the daunting tasks of meeting changing market needs, maintaining market share, and reasserting a technological edge. Now, more than ever, adopting new technologies is a key component in ensuring the successful outcome of new projects--and in producing longterm market success.

null

['Kolan, Krishna C.R.', 'Leu, Ming C.', 'Hilmas, Gregory E.', 'Velez, Mariano']

2021-09-30T18:40:04Z

9/23/10

Mechanical Engineering

null

['https://hdl.handle.net/2152/88274', 'http://dx.doi.org/10.26153/tsw/15215']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['bioactive glass', 'bone tissue repair', 'selective laser sintering', 'scaffold fabrication']

Selective Laser Sintering of 13-93 Bioactive Glass

Conference paper

https://repositories.lib.utexas.edu//bitstreams/34f48c7c-47a5-468f-9800-1109eea67f0d/download

University of Texas at Austin

Bioactive glasses are more promising than biopolymers in fabricating scaffolds for bone tissue repair because they convert to hydroxyapatite, when implanted in vivo. Both direct and indirect selective laser sintering (SLS) methods of 13-93 bioactive glass were considered in this research to study the feasibility of fabricating scaffolds for bone repair applications. Stearic acid was used as the binder in the indirect method to fabricate the scaffolds. The green scaffolds underwent binder burnout and sintering at various soaking conditions between 6750C and 7000C, achieving a maximum compressive strength of 23.6 MPa, which is higher than that of the human cancellous bone. The sintered scaffolds had a pore size varying between 300 µm and 800 µm with 50% apparent porosity.

null

Subramanian, Kam

2018-05-03T20:01:46Z

1993

Mechanical Engineering

doi:10.15781/T2M03ZF44

http://hdl.handle.net/2152/65079

null

1993 International Solid Freeform Fabrication Symposium

Open

['SLS', 'Selective Laser Sintering', 'Center for Materials Science and Engineering']

Selective Laser Sintering of A1203-

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a7a59340-6c60-4c29-b8b8-e37aef0351cb/download

null