ccm/sff-papers · Datasets at Hugging Face

['Li, Ang', 'Thornton, Aaron S.', 'Deuser, Bradley', 'Watts, Jeremy L.', 'Leu, Ming C.', 'Hilmas, Gregory E.', 'Landers, Robert G.']

2021-10-06T20:07:25Z

8/20/12

Mechanical Engineering

null

['https://hdl.handle.net/2152/88429', 'http://dx.doi.org/10.26153/tsw/15366']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['functionally-graded materials', 'Freeze-form Extrusion Fabrication', 'zirconium carbide', 'tungsten', 'ceramics', 'aerospace']

Freeze-Form Extrusion Fabrication of Functionally Graded Material Composites Using Zirconium Carbide and Tungsten

Conference paper

https://repositories.lib.utexas.edu//bitstreams/460f50c3-82b1-48f0-b710-f649f6a9a4b4/download

University of Texas at Austin

Ultra-high-temperature ceramics are being investigated for future use in aerospace applications due to their superior thermo-mechanical properties, as well as their oxidation resistance, at temperatures above 2000°C. However, their brittleness makes them susceptible to thermal shock failure. As graded composites, components fabricated as functionally-graded materials (FGMs) can combine the superior properties of ceramics with the toughness of an underlying refractory metal. This paper discusses the grading of two materials through the use of a Freeze-form Extrusion Fabrication (FEF) system to build FGM parts consisting of zirconium carbide (ZrC) and tungsten (W). Aqueous-based colloidal suspensions of ZrC and W were developed and utilized in the FEF process to fabricate test bars graded from 100%ZrC to 50%-W50%ZrC (volume percent). After FEF processing, the test bars were co-sintered at 2300°C and characterized to determine their resulting density and microstructure. Four-point bending tests were performed to assess the flexural strength of the test bars made using the FEF process, compared to that prepared using conventional powder processing and isostatic pressing techniques, for five distinct ZrC-W compositions. Scanning electron microscopy (SEM) was used to examine the inner structure of composite parts built using the FEF process.

null

['Fu, Q.', 'Jongprateep, O.', 'Abbott, A.', 'Dogan, F.']

2020-02-28T21:00:03Z

2006

Mechanical Engineering

null

['https://hdl.handle.net/2152/80122', 'http://dx.doi.org/10.26153/tsw/7143']

eng

2006 International Solid Freeform Fabrication Symposium

Open

ceramic composites

Freeze-Spray Processing of Layered Ceramic Composites

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b8e1aa70-cd05-46dd-b7cd-065ab0e2721d/download

null

Thermal gradients and associated stresses are critical in designing with ceramic composites having low thermal conductivity. In order to reduce the stresses from thermal gradients, compositional gradients are employed in designing of composite structures. This study addresses development of freeze-spray process to fabricate layered ceramic structures with controlled layer thickness and microstructural development. The composites were processed by spraying of ceramic slurries with low binder content and relatively high solids loadings (up to 40 vol%) on a cooled substrate. The frozen parts were freeze-dried and sintered at elevated temperatures. The relationship between microstructural development and thermal expansion behavior of Al2O3 and Y2O3-stabilized ZrO2 functionally graded ceramic composites is discussed.

null

['Cullom, Tristan', 'Altese, Nicholas', 'Bristow, Douglas', 'Landers, Robert', 'Brown, Ben', 'Hartwig, Troy', 'Soine, David', 'Allen, Aimee', 'Barnard, Andrew', 'Blough, Jason', 'Johnson, Kevin', 'Kinzel, Edward']

2021-11-18T18:10:45Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90451', 'http://dx.doi.org/10.26153/tsw/17372']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['frequency response', 'frequency domain', 'melt pool recoil pressure', 'metal parts', 'additive manufacturing']

Frequency Domain Measurements of Melt Pool Recoil Pressure Using Modal Analysis and Prospects for In-Situ Non-Destructive Testing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/77498550-1a14-43c8-ba19-cdc7dc8ce2f4/download

University of Texas at Austin

Fielding Additively Manufactured (AM) parts requires evaluating both the part’s geometry and material state. This includes geometry that may be optically hidden. Both the geometry and material state affect the vibration response of the parts and modal analysis (identifying natural frequencies) has been shown to be effective for at least simple geometries using ex-situ methods (shaker table and impact hammer excitations). This paper investigates evaluation of the frequency response of metal parts inside the build chamber using the process laser to excite the parts during printing (Renishaw AM250). Vibrations in the part are measured with accelerometers connected to the build plates and used to track the response during printing as during pauses between layers. The laser is modulated at different frequencies and focused onto specific targets to precisely extract the response from individual parts on the build plate. These results are compared to numerical models for metal parts of different geometries and with different material states.

This work was funded by the Department of Energy’s Kansas City National Security Campus which is operated and managed by Honeywell Federal Manufacturing Technologies, LLC under contract number DE-NA0002839.

null

['Allen, Aimee', 'Johnson, Kevin', 'Blough, Jason', 'Barnard, Andrew', 'Hartwig, Troy', 'Brown, Ben', 'Soine, David', 'Cullom, Tristan', 'Bristow, Douglas', 'Landers, Robert', 'Kinzel, Edward']

2021-11-18T18:02:57Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90449', 'http://dx.doi.org/10.26153/tsw/17370']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['defect identification', 'frequency inspection', 'defects', 'additive manufacturing']

Frequency Inspection of Additively Manufactured Parts for Layer Defect Identification

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2a5710fd-1bdb-444b-a89a-9649ec153ec9/download

University of Texas at Austin

Additive manufactured (AM) parts are produced at low volume or with complex geometries. Identifying internal defects is difficult as current testing techniques are not optimized for AM processes. The goal of this paper is to evaluate defects on multiple parts printed on the same build plate. The technique used was resonant frequency testing with the results verified through Finite Element Analysis. From these tests, it was found that the natural frequencies needed to detect the defects were higher than the excitation provided by a modal hammer. The deficiencies in this range led to the development of other excitation methods. Based on these results, traditional methods of resonant part inspection are not sufficient, but special methods can be developed for specific cases.

This work was funded by the Department of Energy’s Kansas City National Security Campus which is operated and managed by Honeywell Federal Manufacturing Technologies, LLC under contract number DE-NA0002839.

null

['Johnson, Kevin', 'Blough, Jason', 'Barnard, Andrew', 'Hartwig, Troy', 'Brown, Ben', 'Soine, David', 'Collum, Tristan', 'Kinzel, Edward', 'Bristow, Douglas', 'Landers, Robert']

2021-11-16T15:14:54Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90309', 'http://dx.doi.org/10.26153/tsw/17230']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['internal defect', 'frequency response inspection', 'dynamic measurement', 'additive manufacturing']

Frequency Response Inspection of Additively Manufactured Parts for Defect Identification

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6e21fd76-bdfe-4869-a4c9-5769796bf840/download

University of Texas at Austin

The goal of this paper is to evaluate internal defects in AM parts using dynamic measurements. The natural frequencies of AM parts can be identified by measuring the response of the part(s) to a dynamic input. Different excitation methods such as a modal impact hammer or shakers can be used to excite the parts. Various methods exist to measure the parts’ responses and find the natural frequencies. This paper will investigate the use of Doppler lasers, accelerometers and Digital Image Correlation (DIC). The parts evaluated in this work include sets of parts that are still attached to the AM build plate, this makes the identification of a faulty part much more difficult as parts on a build plate interact with each other as well as the build plate complicating the responses. Several approaches to these issues will be presented based on the above listed response measurements.

null

['Kulkarni, N.P.', 'Tandra, G.', 'Liou, F.W.', 'Sparks, T.E.', 'Ruan, J.']

2021-09-29T17:53:19Z

9/15/09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88201', 'http://dx.doi.org/10.26153/tsw/15142']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['fuel cells', 'clean energy', 'additive manufacturing', 'fuel cell components']

Fuel Cell Development using Additive Manufacturing Technologies - A Review

Conference paper

https://repositories.lib.utexas.edu//bitstreams/042d0db0-994e-4e0c-be5a-78933ae51376/download

University of Texas at Austin

Fuel cells are being perceived as the future clean energy source by many developed countries in the world. The key today for clean power is the reliance of fuel cells not only to power automobiles but also for residential, small commercial, backup power etc. which calls for production on a large scale. Additive manufacturing is perceived as a way to develop cost effective fuel cells. It imparts flexibility to design different kinds of fuel cells along with reduction in material wastage. This paper deals with the review of additive manufacturing processes for research and development of fuel cell components, such as synthesizing and prototyping new materials for fuel cell components, fuel cell system design and prototyping, designing well sealed fuel cells, bridging from fuel cell design to manufacturing tooling, etc.

null

['Niino, T.', 'Yamada, H.']

2020-02-13T21:09:28Z

8/4/04

Mechanical Engineering

null

['https://hdl.handle.net/2152/79981', 'http://dx.doi.org/10.26153/tsw/7006']

eng

2004 International Solid Freeform Fabrication Symposium

Open

stereolithography

Full-Densification of SLS Parts by Re-Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/68180da6-8976-4839-833f-3f550e3d58d7/download

null

Among commercially available rapid prototyping processes, SLS is the most effective in terms of adaptability of various materials. However, rapid prototyped parts by the process are always porous and the physical properties of the parts are different from dense parts which is to be used in final product. This paper introduces a post process that can densify SLS processed plastic parts to almost 100%. An SLS processed polystyrene part is densified and, resultantly, a much stronger and transparent part is obtained.

null

['Hiller, Jonathan D.', 'Lipson, Hod']

2021-09-28T18:48:14Z

9/15/09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88151', 'http://dx.doi.org/10.26153/tsw/15092']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['recycling', 'multi-material printing', 'recyclable material', 'reusable material']

Fully Recyclable Multi-Material Printing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6b333053-4a90-460b-8d37-f9eb4cee1122/download

University of Texas at Austin

Recycling is often a costly and inefficient process, particularly for objects composed of multiple integrated materials. Here, we demonstrate a freeform fabrication system that prints with fully reusable physical voxels and minimal recycling effort. This new paradigm of digital (discrete) matter enables any number of materials to be printed together in any configuration. The individual voxels may then be reclaimed at will by dissolving the bonds holding the structure together. Coupled with a compatible voxel sorting process, we demonstrate multiple generations of freeform fabricated objects using the same physical material. This opens the door to a flexible desktop fabrication process in which 3D multi-material objects are fully recyclable and re-usable with minimal infrastructure.

null

['Micali, Maxwell K.', 'Dornfeld, David']

2021-10-26T17:51:25Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89538

eng

2016 International Solid Freeform Fabrication Symposium

Open

['CAM', 'additive', 'process planning', 'accessibility', 'configuration space']

Fully Three-Dimensional Toolpath Generation for Point-Based Additive Manufacturing Systems

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a3afd149-7a01-4ed8-90fa-865c1c4e468f/download

University of Texas at Austin

While additive manufacturing and 3D printing achieved notoriety for their abilities to manufacture complex three-dimensional parts, the state of the art is not truly three-dimensional. Rather, the process plans for the majority of these machines rely on a stack of discretized, two-dimensional layers, which results in parts with stair-stepped surfaces, as opposed to being smooth and freeform. This work proposes a change to the 2.5D paradigm by using a configuration space approach to enable toolpath planning in a full three-dimensional space, allowing movements beyond planar slices. Algorithms are also presented to compute toolpaths on non-planar regions. Since the toolpaths take part and machine geometries into account, they are guaranteed to be collision-free. These techniques are relevant to many additive manufacturing technologies, including fused deposition modeling (FDM), directed energy deposition (DED), material jetting, and nozzle-based variants. The result of implementing nonplanar toolpaths is smoother, more continuous part surfaces.

null

['Ge, Wenjun', 'Lin, Feng', 'Guo, Chao']

2021-10-20T21:15:36Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89362

eng

2015 International Solid Freeform Fabrication Symposium

Open

['Electron Beam Selective Melting', 'gradient structures', 'Ti-6Al-4V', 'γ-TiAl']

Functional Gradient Material of Ti-6Al-4V and γ-TiAl Fabricated by Electron Beam Selective Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/beade2e9-8699-4780-a628-c16e07e6c98d/download

University of Texas at Austin

Additive Manufacturing (AM) technologies are very promising in fabricating functionally graded materials. Electron Beam Selective Manufacturing (EBSM) is one widely used AM technology capable of fabricating a variety of materials especially titanium alloys. Previous studies on EBSM process were focused on the manufacturing of one single material. In this study, a novel EBSM process capable of building gradient structures with dual metal materials was developed. Ti6Al4V powders and Ti47Al2Cr2Nb powders were used to fabricate Ti3Al/TiAl and Ti6Al4V/Ti3Al dual metal structures. The chemical compositions, microstructure and micro-hardness of the dual material samples were investigated employing Optical Microscope (OM), Scanning Electronic Microscope (SEM), Electron Probe Micro-Analyzer (EPMA). Results showed that the thickness of the transition zone was about 300μm. The transition zone was free of cracks, and the chemical compositions exhibited a staircase-like change. The microstructure and chemical compositions in different regions were studied. Microhardness was affected by the microstructure. The microstructures turned out to be full lamellar at the TiAl region and basket-weave structure at the Ti3Al and Ti6Al4V region.

null

['Fessler, J.', 'Nickel, A.', 'Link, G.', 'Prinz, F.', 'Fussell, P.']

2018-12-06T21:19:32Z

1997

Mechanical Engineering

doi:10.15781/T22F7KB48

http://hdl.handle.net/2152/71430

eng

1997 International Solid Freeform Fabrication Symposium

Open

['material properties', 'SDM']

Functional Gradient Metallic Prototypes through Shape Deposition Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2b379205-01fb-4e42-9c5f-384cde18a093/download

null

Stanford's SDM laser deposition system has been recently improved to enable the deposition of functionally graded metals through the use of powder mixing. While Shape Deposition Manufacturing has always had the capability to produce multimaterial artifacts, powder mixing enables the deposition ofsingle layers in which material properties can be smoothly varied without discrete interfaces between dissimilar materials. It has been shown that certain materials will completely mix during deposition and form alloys which exhibit material properties intermediate to those ofthe constituent feed powders. To date, oxidation and hardness have been effectively controlled through appropriate mixing of powders. Functional gradient material deposition has been exploited to construct an advanced injection molding tool which transitions from Invar in the center to stainless steel on the outside. The resulting tool exhibited minimal distortion from thermal stress and excellent exterior corrosion resistance.

null

['Choi, Jae-Won', 'Yamashita, Masaki', 'Sakakibara, Jun']

2021-09-29T17:12:01Z

2009-09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88191', 'http://dx.doi.org/10.26153/tsw/15132']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['phacoemulsification', 'cataract surgery', 'irrigation', 'swirl', 'microstereolithography']

Functional Micro/Macro Fabrication Combining Multiple Additive Fabrication Technologies: Design and Development off an Improved Micro-Vane Phacoemulsifier used in Cataract Surgery

Conference paper

https://repositories.lib.utexas.edu//bitstreams/02aa22eb-e77f-4a39-b35b-03570a99c080/download

University of Texas at Austin

null

Microstereolithography (µSL) technology can fabricate complex, three-dimensional (3D) microstructures, although µSL has difficulty producing macrostructures with micro-scale features. There are potentially many applications, where 3D micro-features can benefit the overall function of the macrostructure. One such application has been recently identified in cataract surgery where a medical device, called a coaxial phacoemulsifier, is inserted into the eye through a relatively small incision and used to break the lens apart while removing the lens pieces and associated fluid from the eye through a small tube. In order to maintain the eye at a constant pressure, the phacoemulsifier also includes an irrigation solution that is injected into the eye during the procedure. It has been reported, however, that the impinging flow from the irrigation solution on the corneal endothelial cells in the inner eye damages these cells during the procedure. As a result, we are exploring methods for reducing flow velocities during this procedure, and have designed a complex, 3D micro-vane within a sleeve that introduces swirl into the irrigation solution, and thus, produces a flow with rapidly dissipating flow velocities. However, the fabrication of the sleeve could not be accomplished using µSL alone, and thus, a two-part design was accomplished where a sleeve with the micro-vane was fabricated with µSL and a threaded fitting used to attach the sleeve to the phacoemulsifier was fabricated using an Objet Eden 333 rapid prototyping machine. The new combined device was tested in a water container using particle image velocimetry, and the results showed an ejection of the irrigation fluid through the micro-vane in three different radial direction. It is believed that this new device will reduce damage to endothelial cells during cataract surgery and significantly improve patient outcomes from this procedure. This unique application demonstrates the utility of combining µSL with a macro rapid prototyping technology for fabricating a real macro-scale device with functional, 3D micro-scale features that could not be fabricated using conventional methods.

null

['Noecker II, Fredrick F.', 'DuPont, John N.']

2019-10-23T14:48:10Z

2002

Mechanical Engineering

null

['https://hdl.handle.net/2152/76751', 'http://dx.doi.org/10.26153/tsw/3840']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Net Shaping

Functionally Graded Copper-Steel Using Laser Engineering Net Shaping� Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/491350cf-ddce-4ae3-8270-9571a617f9be/download

null

Laser Engineered Net Shaping (LENS) is an emerging Solid Freeform Fabrication (SFF) process capable of producing fully dense metallic parts with complex shapes directly from a computer-aided drawing (CAD) without the need for molding or tooling. The LENS process also shows promise in producing components with graded compositions. One potential application is the production of steel – copper die casting materials. Copper is currently deposited on dies made out of steel to enhance thermal management, however, difficulties can occur at the Fe-Cu interface, such as, a large solidification temperature range in the Fe-Cu system (which can cause solidification cracking), formation of undesirable phases, and differences in coefficient of thermal expansion. The current research goal is to develop LENS processing parameters to optimize the deposition of functionally graded steel - Copper alloy. Dilution control experiments were carried out to determine the cracking susceptibility of Steel - Cu alloys of varying compositions. The resulting microstructures were characterized by various microscopy techniques. The influence of composition on the resultant cracking susceptibility and microstructure will be discussed. This information is useful for successful deposition of crack-free copper layers onto steel for die casting applications.

null

['Pulugurtha, Syamala R.', 'Newkirk, Joseph', 'Liou, Frank', 'Chou, Hsin-Nan']

2021-09-29T14:24:32Z

2009-09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88181', 'http://dx.doi.org/10.26153/tsw/15122']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['functionally graded materials', 'laser metal deposition', 'intermixing', 'cracking', 'dilution', 'LMD', 'FGMs']

Functionally Graded Materials by Laser Metal Deposition

Conference paper

https://repositories.lib.utexas.edu//bitstreams/61513a20-555c-4286-83fb-343d5a503d6f/download

University of Texas at Austin

Fabrication of functionally graded materials (FGMs) by laser metal deposition (LMD) has the potential to offer solutions to key engineering problems over the traditional metal-working techniques. But the issues that need to be addressed while building FGMs are intermixing in the layers and cracking due to the residual stresses. This paper is to present the study of the effect of process parameters (laser power and travel speed) on the degree of dilution between the substrate (or, previous layer) and powder material for few metallurgical systems.

null

['Chartoff, Richard', 'McMorrow, Brian', 'Lucas, Pierre']

2019-11-21T17:44:42Z

2003

Mechanical Engineering

null

['https://hdl.handle.net/2152/78542', 'http://dx.doi.org/10.26153/tsw/5598']

eng

2003 International Solid Freeform Fabrication Symposium

Open

Nano-Composites

Functionally Graded Polymer Matrix Nano-Composites by Solid Freeform Fabrication: A Preliminary Report

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0a461372-d44b-4b5f-bc52-767cbbde9d1e/download

null

A research program has been initiated to develop a Solid Freeform Fabrication (SFF) technology for combining nanosized particulate or fiber reinforcements with a photocurable thermoset matrix resin in order to produce functional graded composites. The composites that are being studied initially are optical components filled with nano-phase ceramic particles that form gradient refractive index lenses (GRIN). The Solid Freeform Fabrication (SFF) method employs an ink-jet deposition (IJD) process to form the composites. The IJD process has the advantage of incorporating nano-reinforcements into a low viscosity matrix resin that is relatively easy to process and rapidly photocures to produce functional polymeric parts. It also has the advantage that major modifications to the basic SFF processing methodology are not necessary. The emphasis in the program is on demonstrating the feasibility of this approach for fabrication of gradient refractive index lenses (GRIN), which are flat instead of the traditional spherical lens geometry. As a result these lenses will be less costly to produce than conventional curved lenses. SFF is an ideal technique for meeting the needs of GRIN lens fabrication because changes in composition can be made from layer to layer and even within each layer, allowing for the introduction of compositional and structural gradients. Thus it has the potential for creating the spatial material distributions required for designing computer optimized, custom made GRIN lenses. Integral to the SFF process are computer design procedures that specify the exact material deposition patterns that need to be employed in order to optimize the performance of the GRIN lens. The optical nano-composites will serve as a model system that we will use to work out the many challenges for implementing a viable SFF polymer composites technology. We then will make use of the information obtained and lessons learned from the work on optical composites and extend the development to structural composites that incorporate nano-particulate clays and carbon nanofibers.

null

['Park, Seok-Min', 'Crawford, Richard H.', 'Beaman, Joseph J.']

2019-03-12T16:32:06Z

1999

Mechanical Engineering

null

['https://hdl.handle.net/2152/73598', 'http://dx.doi.org/10.26153/tsw/740']

eng

1999 International Solid Freeform Fabrication Symposium

Open

['FGM', 'SFF']

Functionally Gradient Material Design and Modeling Using Hypertexture for Solid Freeform Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e935b0b4-c871-45fe-9b1e-1fd9677342d7/download

null

SFF technologies have the potential to become manufacturing process that are capable of producing parts that have not been feasible by other techniques. The fabrication of Functionally Gradient Material (FGM) is one of the possible candidate. It is critical.to provide three dimensional material gradient data in the solid model to fabricate FGM. The approach is to model spatially varying material density distribution on implicit solid geometry using a hypertexturing scheme and a procedural volumetric modeling. It is essentially an extension of procedural solid texture synthesis, which has been effectively used to model cloud, gas, and flow stream. It will save the amount of information storage especially when the gradient pattern is repeating. Geometric operation becomes convenient since the material data are linked to the geometry only by the reference surfaces.

null

['Park, Seok-Min', 'Crawford, Richard H.', 'Beaman, Joseph J.']

2019-09-23T16:34:03Z

2000

Mechanical Engineering

null

['https://hdl.handle.net/2152/75958', 'http://dx.doi.org/10.26153/tsw/3057']

eng

2000 International Solid Freeform Fabrication Symposium

Open

Fabrication

Functionally Gradient Material Representation by Volumetric Multi-Texturing for Solid Freeform Fabrication 350

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c6c0c3aa-d80e-4f90-af60-e56091629224/download

null

In order to fabricate parts from Functionally Gradient Materials (FGM) by layered manufacturing methods, the SFF community needs a method to represent material distributions in solid models. Gradient material distribution requires accurate and systematic representation, and must be compatible with existing geometric data. This paper presents a method, called Volumetric Multi Texturing, to represent a three dimensional density gradient by exploiting hypertexturing and volumetric density functions. This method utilizes procedural and implicit methods to design/acquire density information. The implicit procedural approach, as opposed to an input database, allows users to interactively create and modify the design patterns without explicitly changing the values stored in the database. Further, it promises convenience in process planning, and efficiency in data storage and computation time. The theoretical approach, design procedure, and tool path generation for fabrication of an example part are presented in the paper. The design procedure presented is based on specifying the material gradient by surface modification.

We gratefully acknowledge the financial support of the National Science Foundation under grant number DMI9618034.

null

['Gasdaska, C.', 'Clancy, R.', 'Ortiz, M.', 'Jamalabad, V.', 'Virkar, Anil', 'Popovitch, Dragan']

2019-03-01T17:35:05Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73517', 'http://dx.doi.org/10.26153/tsw/667']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['microstructures', 'CTE']

Functionally Optimized Ceramic Structures

Conference paper

https://repositories.lib.utexas.edu//bitstreams/db26107e-5d8a-4802-a109-9eddb6320e30/download

null

The feasibility of using the Fused Deposition of Ceramics (FDC) process to rapidly fabricate functional quality advanced ceramic components has been demonstrated multiple extrusion heads enable the deposition of spatially engineered ceramic microstructures on the scale of 250 um. This unique capability of FDC allows components to be built with combinations of materials and properties that are difficult or impossible to produce using conventional fabrication processes. Some concepts will be presented, along with examples of multiple material laminates produced using FDC. Strength data will be presented which demonstrates the performance improvement possible using spatially engineered microstructures.

null

['Bunnell, D.E.', 'Das, S.', 'Bourell, D.L.', 'Beaman, J.B.', 'Marcus, H.L.']

2018-11-08T15:45:04Z

1995

Mechanical Engineering

doi:10.15781/T26D5PX0B

http://hdl.handle.net/2152/69893

eng

1995 International Solid Freeform Fabrication Symposium

Open

['surface tension', 'liquid-vapor surface tension', 'LPS']

Fundamentals of Liquid Phase Sintering During Selective Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2221e141-b608-4c8d-a6f4-625acc6825db/download

null

One of the advantages of the Selective Laser Sintering (SLS) process is that a variety of materials can be processed. However, the goal of being able to produce fully dense metal parts with no post processing has been elusive. Using Selective Laser Sintering to produce metal parts with full density without post processing poses a challenge since both the processing conditions and the metal system must be controlled. This article describes two metallurgical mechanisms by which loose metal powder beds could be sintered to nearly full density using a scanning laser beam. The mechanisms are particle rearrangement during liquid phase sintering (LPS) and in-situ infiltration. Some of the particles, when heated by the laser radiation, melt and form a liquid. Ifthis liquid has certain physical properties (e.g., low viscosity and high surface tension) and wets the other solid particles, then the SLS process can in theory produce dense layers by either mechanism. The purpose of this study is to determine the process and material selection parameters required to achieve fully dense parts during direct Selective Laser Sintering of metal.

null

['Bunnell, D.E.', 'Bourell, D.L.', 'Marcus, H.L.']

2018-10-03T18:32:54Z

1994

Mechanical Engineering

doi:10.15781/T2DR2PT81

http://hdl.handle.net/2152/68674

eng

1994 International Solid Freeform Fabrication Symposium

Open

['liquid phase sintering', 'selective laser sintering', 'sinter powder particles']

Fundamentals of Liquid Phase Sintering Related to Selective Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8083318e-0629-4a68-8c61-c22e20ea66cf/download

null

Liquid phase sintering is one of the underlying principles that must be modeled and understood when the Selective Laser Sintering (SLS) process is used. This paper describes the initial studies being conducted to measure surface tension of metal alloys used for SLS. A low melting point solder was used to verify the wetting balance and pendant drop techniques and equipment for determining surface tension. The liquid-solid, liquid-vapor, and solid vapor surface tension of 80 Sn - 20 Pb solder on mild steel was determined to be 245, 417, and 662 dynes/cm.

null

['Chatham, Camden A.', 'Talley, Samantha J.']

2024-03-25T22:15:47Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124316', 'https://doi.org/10.26153/tsw/50924']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['PBF/LB', 'crystallization', 'additive manufacturing']

Fundamentals of Polymer Crystallization in Laser Powder Bed Fusion for New Material Screening

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a5977508-a28c-4223-b14a-d46dffb4fc48/download

University of Texas at Austin

Although laser powder bed fusion (PBF/LB) was one of the first industrially viable additive manufacturing (AM) methods for end-use part production, polyamides remain grossly dominant at both the commercial- and research scale. The research community continues to develop and refine “rapid screening” methods for evaluating the suitability of new polymers for PBF/LB. The so-called “SLS Process Window,” which is the difference between melting and crystallization temperature measured at 10 K min-1 as originally outlined in the patent literature, is perhaps the most often reported screening method. Although perhaps appropriate as part of a larger study, the simplistic guidelines put forth by the “SLS Process Window” are not sufficiently scientifically rigorous to understand how crystallization kinetics affects successful 3D printing. The common understanding of the SLS Process Window omits details from published theories of polymer crystallization. as evidenced by published assumptions and methods in PBF/LB process modeling papers. The authors explain polymer crystallization in the PBF/LB context and propose replacing the “process window” with crystallization halftime and physical gelation for new material screening. These measurements better represent behavior critical for ensuring a lengthy coexistence of solid powder and molten polymer affecting warp-free parts.

null

Jacobs, Paul F.

2018-04-19T18:14:11Z

1992

Mechanical Engineering

doi:10.15781/T24M91T5H

http://hdl.handle.net/2152/64400

eng

1992 International Solid Freeform Fabrication Symposium

Open

['stereolithography', 'Research & Development', 'photons', 'rapid prototyping']

Fundamentals of Stereolithography

Conference paper

https://repositories.lib.utexas.edu//bitstreams/03e894c8-0920-41fe-a42c-9e91539cebc4/download

null

It has only been a little over four years since the introduction of the first StereoLithography system, the SLA-1. From early 1988 until J.une 1992 over 300 SLA-1, SLA-250, SLA-190 and SLA-500 units have been sold by 3D Systems. These machines, currently operating in 20 countries on five continents, amount to about 90 percent of all the rapid prototyping systems now in use.

null

['Hauser, C.', 'Childs, T. H. C.', 'Badrossamay, M.']

2020-02-14T15:36:50Z

2004

Mechanical Engineering

null

['https://hdl.handle.net/2152/79986', 'http://dx.doi.org/10.26153/tsw/7011']

eng

2004 International Solid Freeform Fabrication Symposium

Open

bed temperature

Further Developments in Process Mapping and Modelling in Direct Metal Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9a9ee21c-52d1-4e46-91a6-fefc794493cd/download

null

This paper advances previous reported work on the mapping and modelling of single tracks and layers produced in powder beds of tool steel and stainless steel powders by a CO2 laser. For single tracks it reports on predicted and simulated track masses. It validates the simulations, including the use of absorption close to 1.0 when cylindrical tracks are formed. It also reports on melt pool temperature calculations and estimated melt pool dimensions which are used, in conjunction with bed physical properties, to explain why the single tracks form as either continuous with a crescent shape cross-section, continuous with an elliptical section, discontinuously irregularly broken, discontinuously balled or only partially melted as scan speeds and laser powers change. It then extends its scope, experimentally, to consider effects of scan spacing on single layer formation.

null

['Obielodan, J.O.', 'Stucker, B.E.']

2021-09-28T20:19:03Z

9/18/09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88173', 'http://dx.doi.org/10.26153/tsw/15114']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['multi-material fabrication', 'ultrasonic consolidation', 'bond quality']

Further Exploration of Multi-Material Fabrication Capabilities of Ultrasonic Consolidation Technique

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3715e4aa-84ae-4933-b861-1cbd14dec151/download

University of Texas at Austin

The increasing interest in engineering designs involving parts with multiple materials, and function specific members has placed more demand for technologies to fabricate such parts. This work discusses results of further exploration of multi-material freeform fabrication using ultrasonic consolidation. Various combinations of materials, including Titanium, Silver, Tantalum, Aluminum, Molybdenum, stainless steel, Nickel, Copper, and MetPreg have been studied. Some were found to be effective as a suitable intermediate layer between difficult to join materials. Elemental Boron particles were added in situ between selected materials to modify the bonding characteristics. Microstructures of deposits were studied to evaluate bond qualities. Results show evidence of good bonds between various combinations of materials, thus illustrating increasing potential for multi-material freeform fabrication using ultrasonic consolidation.

null

['Yang, Li', 'Lassell, Austin', 'Perez Vilhena Paiva, Gustavo']

2021-10-21T21:54:03Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89452

eng

2015 International Solid Freeform Fabrication Symposium

Open

['electropolishing', 'Ti6Al4V', 'electron beam melting', 'process parameters']

Further Study of the Electropolishing of Ti6Al4V Parts Made via Electron Beam Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a64df3ed-1413-4c68-ab0d-1b8819e4f929/download

University of Texas at Austin

In this study, the effect of various parameters including the voltage, current, polishing time, temperature and electrode spacing on the electropolishing quality of Ti6Al4V samples made via electron beam melting was investigated using specialty designed research setups. The relationships between these process parameters and the surface roughness of the parts were established experimentally.

null

['Simonelli, M.', 'Tse, Y.Y.', 'Tuck, C.']

2021-10-06T20:13:25Z

8/22/12

Mechanical Engineering

null

['https://hdl.handle.net/2152/88430', 'http://dx.doi.org/10.26153/tsw/15367']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', 'Ti-6Al-4V', 'microstructural features', 'texture analysis']

Further Understanding on Ti-6Al-4V Selective Laser Melting Using Texture Analysis

Conference paper

https://repositories.lib.utexas.edu//bitstreams/cc466bf5-a961-4534-ab43-561258e47bae/download

University of Texas at Austin

Selective laser melting (SLM) has shown to be an attractive manufacturing route to produce Ti-6Al-4V components. In the present study, the relation between the texture evolution and a particular set of process parameters adopted for the production of near fully dense components was investigated. The aim of this investigation was to understand which microstructural features can be tailored during the SLM production. The microstructural characterisation of the as-built components was carried out using various microscopy techniques including optical, scanning electron and transmission electron microscopy. Phases and texture analysis were carried out using backscattered electron imaging and electron backscattered diffraction. It was found that the components consist of ’ martensitic phase precipitated from prior β columnar grains. It was found that the α’ martensitic laths develop from the parent β grains following the Burgers orientation relationship. The texture of the prior β phase was calculated and compared to the measured α’ texture. It was found that at each layer processing the α’ texture is retained and variant selection takes place. The observed microstructural details will be discussed in relation to the SLM parameters.

null

['Mireles, Jorge', 'Espalin, David', 'Roberson, David', 'Zinniel, Bob', 'Medina, Francisco', 'Wicker, Ryan']

2021-10-06T22:00:03Z

8/22/12

Mechanical Engineering

null

['https://hdl.handle.net/2152/88457', 'http://dx.doi.org/10.26153/tsw/15394']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['Fused Deposition Modeling for metals', '3-dimensional metallic structures', 'electronics', 'electronic circuitry']

Fused Deposition Modeling of Metals

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3f5230cc-455e-4ec0-80d8-04a5ed694d34/download

University of Texas at Austin

Studies have been conducted to improve previous work performed in developing a Fused Deposition Modeling for metals (FDMm) system used for applications in electronics and fabrication of 3-dimensional metallic structures. A FDM 3000 system was modified to achieve controlled deposition of eutectic Bi58Sn42 and non-eutectic Sn60Bi40 materials. Toolpath command modifications were required to achieve controlled deposition of metals. Results are presented which include a redesigned metal deposition head, computer modeling of fluid flow, and finally examples of the successful deposition of metal alloys. Additionally, FDMm-fabricated metal samples were prepared and analyzed using optical and scanning electron microscopy. Controlled deposition of metals using FDMm allows for parts that can be used for jigs and fixtures, electroforming mandrels, encapsulation molds, dies, electronic joining applications, as well as printing 3-dimensional electronic circuitry.

null

['Espalin, David', 'Arcaute, Karina', 'Rodriguez, David', 'Medina, Frank', 'Posner, Matthew', 'Wicker, Ryan']

2021-09-29T17:19:01Z

2009-09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88192', 'http://dx.doi.org/10.26153/tsw/15133']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['polymethylmethacrylate', 'fused deposition modeling', 'reconstructive surgery', 'scaffolds', 'mechanical properties']

Fused Deposition Modeling of Polymethylmethacrylate for Use in Patient-Specific Reconstructive Surgery

Conference paper

https://repositories.lib.utexas.edu//bitstreams/66e3a74d-b5f7-4b48-8081-1bbdbd5e40e4/download

University of Texas at Austin

facial reconstruction and as bone cement and antibiotic-impregnated spacers in orthopaedics. The polymerization of PMMA in-situ causes tissue necrosis and other complications due to the long surgical times associated with mixing and shaping the PMMA. PMMA is a thermoplastic acrylic resin suitable for extrusion in FDM thus 3D anatomical models can be fabricated prior to surgery directly from medical imaging data. The building parameters required for successful FDM fabrication with medical-grade PMMA filament (1/16”Ø) were developed using an FDM 3000. It was found that a liquefier and envelope temperature of 235ºC and 55ºC, respectively, as well as increasing the model feed rate by 60%, were necessary to properly and consistently extrude the PMMA filament. Scaffolds with different porosities and fabrication conditions (tip wipe frequency and layer orientation) were produced, and their compressive mechanical properties were examined. Results show that both the tip wipe frequency (1 wipe every layer or 1 wipe every 10 layers) and layer orientation (transverse or axial with respect to the applied compressive load) used to fabricate the scaffolds, as well as the porosity of the scaffold had an effect on the mechanical properties. The samples fabricated with the high tip frequency had a larger compressive strength and modulus (Compressive strength: 16 ± 0.97 vs. 13 ± 0.71 MPa, Modulus: 370 ± 14 vs. 313 ± 29 MPa, for samples fabricated in the transverse orientation with 1 tip wipe per layer or 1 tip wipe per 10 layers, respectively). Also, the samples fabricated in the transverse orientation had a larger compressive strength and modulus than the ones fabricated in the axial orientation (Compressive strength: 16±0.97 vs. 13±0.83 MPa, Modulus: 370±14 vs. 281±22 MPa, for samples fabricated with 1 tip wipe per layer, in the transverse and axial orientation, respectively). Overall, the compressive strain for the samples fabricated with the four different conditions ranged from 8 – 12%. In regards to the porosity of the samples, in general, the stiffness, yield strength and yield strain decreased when the porosity increased (Compressive strength: 12±0.71 – 7±0.95 MPa, Modulus: 248±10 – 165±16 MPa, Strain: 7±1.5 – 5±1% for samples with a porosity ranging from 55 – 70%). The successful FDM fabrication of patient-specific, 3D PMMA implants with varying densities, including the model of a structure to repair a cranial defect and the model of a femur, was demonstrated. This work shows that customized structures with varying porosities to achieve tailored properties can be designed and directly fabricated using FDM and PMMA.

null

['Onagoruwa, Seyi', 'Bose, Susmita', 'Bandyopadhyay, Amit']

2019-10-10T17:36:04Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76178', 'http://dx.doi.org/10.26153/tsw/3267']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Ceramics

Fused Deposition of Ceramics (FDC) and Composites

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a49849fd-b841-4a0b-bb10-6944145dbc40/download

null

Fabrication of functional ceramics and composites has been attempted using fused deposition of ceramics process. In this work, first a polypropylene (PP) binder system has been developed for the FDM. The PP binder system was mixed with ceramic powders and then extruded in the form of filament for the FDC. Controlled porosity ceramic parts were directly fabricated using a FDM 1650 machine with mullite, fused silica and titania powder loaded green filaments. The parts were then binder removed and sintered. Some of the porous parts were then infiltrated in Al metal to form the metal-ceramic composites. This article discusses feedstock development, part fabrication and methods to improve the quality of parts during processing.

null

['Agarwala, M.K.', 'Bandyopadhyay, A.', 'Weeren, R. van', 'Langrana, N.A.', 'Safari, A.', 'Danforth, S.C.', 'Jamalabad, V. R.', 'Whalen, P. J.', 'Donaldson, R.', 'Pollinger, J.']

2018-11-14T17:59:59Z

1996

Mechanical Engineering

doi:10.15781/T2B854376

http://hdl.handle.net/2152/70253

eng

1996 International Solid Freeform Fabrication Symposium

Open

['SFF', 'FDC', 'structural ceramics']

Fused Deposition of Ceramics (FDC) for Structural Silicon Nitride Components

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c922d9f2-3bfc-4d2d-abce-054b97f6beaf/download

null

Fused Deposition of Ceramics is aI! SFF tec~que based on comm~rcial FDMTM ~echno.logy, f?r fabrication of structural and functIonal cerannc components. ThIS study descnbes, ill detail, process improvements made in pre-FDC, FDC, and post-FDC fabrication steps to achieve functional properties in commercial GS-44 silicon nitride ?omponents. . Microstructural characterization of sintered FDC parts reveals microstructures simllar to convennonally processed silicon nitride material. Mechanical properties of FDC processed silicon nitride bend bars and toughness samples were evaluated. These property evaluation studies demonstrate that mechanical properties similar to commercial GS-44 silicon nitride materials can be achieved using FDC. The study also describes results achieved on fabrication of complex components from silicon nitride using FDC.

null

['Agarwala, M.K.', 'Weeren, R. van', 'Bandyopadhyay, A.', 'Whalen, P.J.', 'Safari, A.', 'Danforth, S.C.']

2018-11-14T20:13:24Z

1996

Mechanical Engineering

doi:10.15781/T2NK36Q96

http://hdl.handle.net/2152/70261

eng

1996 International Solid Freeform Fabrication Symposium

Open

['SFF', 'FDC', 'fabrication of polymer']

Fused Deposition of Ceramics and Metals : An Overview

Conference paper

https://repositories.lib.utexas.edu//bitstreams/fc19efbc-f09b-4ba0-9fd9-a49f495fb713/download

null

Fused Deposition of Ceramics (FDC) and Metals (FDMet) are SFF techniques, based on commercial FDMTM technology, for rapid fabrication of functional ceramic and metal parts from powderlbinder materials. This work demonstrates the possibility of applying FDC and FDMet to a variety of ceramic and metal particulate systems for fabrication of components/parts/devices for wide ranging applications such as tooling, investment casting cores and shells, structural and functional components, etc. Several particulate ceramic and metal systems have been explored for FDC and FDMet. The particulate systems explored vary in particle size from nano-crystalline (WC-Co) to coarse (>100 Jlm Si(2) particles. The material systems explored for FDC and FDMet vary from conventional ceramic and metal systems such as Si02 and stainless steel to advanced materials such as Si3N4 and PZT. FDC and FDMet of such a variety of material systems using a commercial FDMTM system has been made feasible by development of a unique series of binders, as well as optimized FD processing, binder removal techniques and sintering conditions.

null

['Clancy, R.', 'Jamalabad, V.', 'Whalen, P.', 'Bhargava, P.', 'Dai, C.', 'Rangarajan, S.', 'Wu, S.', 'Danforth, S.', 'Langrana, N.', 'Safari, A.']

2018-11-29T20:35:44Z

1997

Mechanical Engineering

doi:10.15781/T2416TJ9C

http://hdl.handle.net/2152/70341

eng

1997 International Solid Freeform Fabrication Symposium

Open

['filament buckling', 'compounded material']

Fused Deposition of Ceramics: Progress Towards a Robust and Controlled Process for Commercialization

Conference paper

https://repositories.lib.utexas.edu//bitstreams/03426575-cdc6-4b8a-87fd-b239597c1f0f/download

null

The feasibility of using the Fused Deposition ofCeramics (FDC) process to rapidly fabricate functional quality advanced ceramic components has been demonstratedl - 5 . This direct manufacturing technique, by eliminating the need for costly tooling, dramatically reduces functional prototype development time. This makes it suitable for small quantity production runs and complex parts. The move from 'feasibility" to a robust, reliable commercial fabrication tool requires that every aspect ofthe manufacturing be understood and brought under control. An overview ofthe five basic process steps in FDC: batch compounding, filament fabrication, fused deposition, binder burnout and sintering will be presented in light ofthis drive toward a robust process. Tools such as Statistical Process Control and Experimental Design techniques are being used to monitor, improve, and stabilize each step and sub-process. Hardware and software modifications have been made to the FD machine to effect the required changes. This paper will identify the remaining technical barriers to commercialization and our progress in addressing these issues.

null

['Benza, Donald', 'Chatham, Camden A.', 'Baker, Jonathan', 'Johnson, Devin']

2024-03-25T22:17:48Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124317', 'https://doi.org/10.26153/tsw/50925']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['polymer', 'fusion', 'additive manufacturing']

Fused Filament Fabrication of Polymer Blends with in situ Layerwise Chemical Modifications

Conference paper

https://repositories.lib.utexas.edu//bitstreams/001d89dc-9ce8-4a6d-8727-a4d3bdbf0d91/download

University of Texas at Austin

The layerwise paradigm of additive manufacturing advertises voxel level control over both geometry and material properties of parts although the latter is difficult to achieve. Recently the Savannah River National Laboratory has demonstrated a new technique for voxel level material property control via layerwise surface chemical modification of polycarbonate homopolymer with UV and ozone during manufacturing. This technique can be utilized to modify each respective phase of a blended polymer feedstock to increase chemical similarity in preparation for potential in situ interphase crosslinking. Successful crosslinking of dissimilar polymers during manufacturing could allow for further voxel level material property control than modification of a homopolymer could allow. Test feedstock comprised of melt mixed polycarbonate and polystyrene homopolymers, an immiscible polymer blend, were printed in an atmosphere containing ozone and UV light. FTIR measurements indicate both phases of the blend may be modified simultaneously in situ to form new oxygen functional groups, increasing chemical similarity. Calorimetric and thermomechanical characterization show no indicators of increased compatibilization due to the treatment. Uniaxial tension to failure experiments demonstrates minimal loss of mechanical properties as the blend phase to phase interfacial properties dominates the behavior despite the chemical modifications. Future work will focus on understanding the complex relationships between configurable processing parameters (layer height, print speed, temperature, etc), reaction site creation density, and blend degradation prior to further modification while identifying a suitable crosslinker to improve mechanical and thermal properties of the blend.

null

['Zhang, J.', 'Van Hooreweder, B.', 'Ferraris, E.']

2021-12-01T21:49:45Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90626', 'http://dx.doi.org/10.26153/tsw/17545']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['fused filament fabrication', 'moon', 'heat transfer']

Fused Filament Fabrication on the Moon

Conference paper

https://repositories.lib.utexas.edu//bitstreams/21c9a496-868b-4511-a58d-a1513a8c5981/download

University of Texas at Austin

Additive manufacturing (AM) techniques possess the capabilities to rapidly produce complex and customised parts, typically in low-volume and with reduced material us- age and preparation tools . These attributes magnify their indispensability when the availability of materials and equipment is limited. It can be such a case for off-Earth manufacturing, e.g. in manned lunar explorations. This article presents a preliminary discussion on the possibility of performing fused filament fabrication (FFF) on the Moon from the perspective of heat transfer in printed parts. It makes use of experimen- tal data and simulations to quantify the significance of each heat transfer mechanism taking place during printing. The quantification then enables us to investigate how the lunar environment affects the cooling in the printed parts. Finally, FFF on the Moon is predicted to be feasible. Yet, apparent differences in the process window and types of applications are pointed out as compared with the counterpart printing activities on the Earth. The full paper may be found in a special issue of the TMS publication JOM, March 2022.

null

['Valenti, Justin D.', 'Bartolai, Joseph', 'Yukish, Michael A.']

2024-03-26T17:04:49Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124376', 'https://doi.org/10.26153/tsw/50984']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['G-wing', 'software', 'wings', 'material extrusion', 'additive manufacturing']

G-WING: A NOVEL SOFTWARE TOOL FOR TOOLPATH-CENTRIC DESIGN OF WINGS FOR MATERIAL EXTRUSION

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2b46e629-7b8e-4c5b-bd83-16be4c2a82c4/download

University of Texas at Austin

A novel software tool for the design of small aircraft wings to be fabricated with material extrusion is presented where the key requirement of the tool is to minimize the time from identified need to realized capability. The tool, named G-Wing, uses rapid design algorithms based on lifting line theory to determine the outer-mold line of the wing based on desired aerodynamic behavior. The resulting wing shape and flight-load distribution are given to a structural design algorithm to determine the internal structure of the wing based on both expected flight loads and manufacturing constraints. Finally, manufacturing instructions in the form of G-Code are created directly from the wing shape and internal structure. This process removes explicit geometric modeling and slicing from the critical design path and directly converts airfoil coordinates to perimeter G-Code points, minimizing the introduction of geometric error. This process has been used to design and fabricate multiple small aircraft wings that have successfully flown. G-Code for an example wing section is shown to be lighter and require less build time compared to G-Code generated by a standard CAD-slicing toolchain.

null

['Smith, Steven L', 'Paul, Jerri']

2018-11-09T14:42:02Z

1996

Mechanical Engineering

doi:10.15781/T2765B14Q

http://hdl.handle.net/2152/69921

eng

1996 International Solid Freeform Fabrication Symposium

Open

['Raytheon-Waco', 'Rapid Prototyping', 'high-volume production']

Gaining Competitive Advantage By Using Rapid Prototyping in Aircraft Modification

Conference paper

https://repositories.lib.utexas.edu//bitstreams/68b4d9ba-bdae-43b2-ad29-43f9b373ede2/download

null

Raytheon-Waco (formerly Chrysler Technologies Airborne Systems) is an aircraft modification facility in Waco, TX, specializing in military, executive, and head-of-state aircraft modifications. Raytheon-Waco has over 25 years of aircraft modification experience, and is a leading contractor for major US and foreign government programs that require system design, airframe modification, installation, flight testing, and post-delivery technical and logistical support. Current programs at Raytheon-Waco include foreign government Head-of-State widebody aircraft modifications consisting ofluxury interiors, secure communications, and airframe modifications, and US and foreign military aircraft modifications involving electronics, communications, avionics, and airframe modifications. The aircraft modification industry is highly competitive, with a variety of very competent companies constantly trying to increase market share and move into new markets. RaytheonWaco has focused primarily on military communications and transport aircraft, and Head-ofState wide-body aircraft. Due to increasing competition and customer cost-conscientiousness, Raytheon-Waco is working to reduce cost and cycle time while maintaining its reputation for delivering on time and within budget. There is also movement into other markets, such as lowercost wide-body executive aircraft. Raytheon-Waco is currently transitioning to a paperless design process, with the ultimate goal of performing all design, analysis, manufacturing, and aircraft installation from CAD models without requiring paper drawings. Increased use of electronic models will also allow more parallel processes to be performed, eliminating many of the sequential design steps currently required. Among the steps that will be performed in parallel will be detailed design, manufacturing and installation planning, technical publications, and design analysis. Without improved initial designs, parallel work will only lead to increased rework and wasted effort. Rapid prototyping is a key factor in reducing risks associated with concurrent processes, and its benefits are critical to efforts to reduce the cost and schedule of future aircraft modifications.

null

['Harrison, Shay', 'Costa, Chris F.', 'Jakubenas, Kevin J.', 'Crocker, James E.', 'Marcus, Harris L.']

2018-11-29T21:53:28Z

1997

Mechanical Engineering

doi:10.15781/T2Z893132

http://hdl.handle.net/2152/70347

eng

1997 International Solid Freeform Fabrication Symposium

Open

['SALD', 'TMS']

Gas Phase SFF Control System for Silicon Nitride Deposition by SALD/SALDV

Conference paper

https://repositories.lib.utexas.edu//bitstreams/243c803b-c8e4-4757-bced-da51633afe05/download

null

: A closed-loop laser scanning and temperature control system has been developed for SALD/SALDVI. Temperature control is especially important in SALD/SALDVI because temperature plays a defining role in both composition and deposition rate. The control system for SALD/SALDVI is presented which provides .STL file interpretation, real time temperature control, and laser response modeling, all on a PC. This control system was utilized with the SALD/SALDVI techniques for depositing silicon nitride. Characteristics of ShN4 fabricated shapes are discussed, including composition, morphology, and electrical properties.

null

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

2021-10-05T14:00:38Z

2011

Mechanical Engineering

null

['https://hdl.handle.net/2152/88374', 'http://dx.doi.org/10.26153/tsw/15313']

eng

2011 International Solid Freeform Fabrication Symposium

Open

['solid freeform', 'ceramic materials', 'Selective Area Laser Deposition']

Gas Phase Solid Freeform for Fabrication of Three-dimensional Ceramic Structures

Conference paper

https://repositories.lib.utexas.edu//bitstreams/aff0062f-298c-4ff4-81a7-63ad423ab451/download

University of Texas at Austin

Solid free form of ceramic materials can be achieved by deposition from the gas phase. The Selective Area Laser Deposition, or SALD, technique can be utilized to make ceramic depositions with a uniform chemical composition. In order to make all classes of ceramics, including carbides, nitrides, and oxides, selection of a precursor is an essential step. Often the correct precursor for the deposition requires a special environment, namely, one that can be uniformly heated. System design for a heated deposition chamber is discussed as well as preliminary tests of the system functionality. Silicon Carbide depositions were performed as a means of evaluating system parameters.

null

['Maxwell, James', 'Pegna, Joseph', 'Hill, Eric']

2018-10-05T17:30:49Z

1995

Mechanical Engineering

doi:10.15781/T2M61C83P

http://hdl.handle.net/2152/68719

eng

1995 International Solid Freeform Fabrication Symposium

Open

['3D mode of pyrolytic LCVD', 'SALD', 'photolytic']

Gas-Phase Laser-Induced Pyrolysis of Tapered Microstructures

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f9930f84-2914-41ac-b48f-f72356b5b9aa/download

null

Gas-phase Selective Area Laser Deposition (SALD) is a useful freeform fabrication tool for the prototyping of simple three-dimensional microstructures. Using this method, slender graphite and nickel rods of various diameters were grown from ethylene and nickel tetracarbonyl, respectively. By varying the laser power during growth, tapered cone-like structures were also generated. Rod diameters and material morphology were correlated with the SALD process parameters to demonstrate the mechanisms through which steady-state rod growth occurs--and through which it can be controlled. Rods, and other similar microstructures, have many useful applications, and are preliminary building blocks for further modelling and development of the SALD process as a micromachining tool. Keywords: Laser chemical vapor deposition, LCVD, SALD, 3-dimensional growth, micro fabrication, rapid prototyping, micro electro mechanical systems, pyroiysis, graphite, nickel, rods, cone.

null

['Harrison, S.', 'Marcus, H.L.']

2019-02-26T20:12:40Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73493', 'http://dx.doi.org/10.26153/tsw/643']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['ceramic parts', 'surface material']

Gas-Phase Selective Area Laser Deposition(SALD) Joining of SiC Tubes with SiC Filler Materia

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b1ac616e-dedb-4ea0-9660-20c07c9da43d/download

null

The laser-driven, gas-phase based SFF technique for joining together ceramic components with ceramic filler material, known as Selective Area Laser Deposition(SALD) Joining, was utilized in fabricating joined silicon carbide structures. Specifically, silicon carbide tubes were 'welded' together by depositing silicon carbide from a gas phase reaction. Two different precursor environments were examined, one a tetramethylsilane/hydrogen mixture and the other composed of methyltrichlorosilane. The quality of the joints were examined by bend tests and hermeticity measurements. In addition, the composition and morphology of the silicon carbide deposit was studied and is discussed here

null

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

2019-09-23T15:25:31Z

2000

Mechanical Engineering

null

['https://hdl.handle.net/2152/75935', 'http://dx.doi.org/10.26153/tsw/3034']

eng

2000 International Solid Freeform Fabrication Symposium

Open

Fabrication

GAS-PHASE SOLID FREEFORM FABRICATION OF SiC CERMETS USING SALDVI

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e1072cfa-797c-4c22-8afc-ec68198113ad/download

null

Selective Area Laser Deposition Vapor Infiltration (SALDVI) is an experimental solid freeform fabrication (SFF) technique aimed at the direct fabrication of ceramic and ceramic/metal structures and composites. SALDVI uses a layer-by-layer approach in which powders are infiltrated with solid material deposited from gas precursors by chemical vapor deposition (CVD) using laser heating. Experiments have been performed with CO2 and Nd:YAG lasers using the silicon carbide forming gas precursor Si(CH3)4 and Cu, Mo, and Ni metal powders. The microstructure of the resulting SiC/metal cermets was investigated in relation to the processing history. In some cases, the formation of intermetallic silicide phases was observed

null

['Carter, W.T.', 'Emo, D.J.', 'Abbott, D.H.', 'Bruck, C.E.', 'Wilson, G.H.', 'Wolfe, J.B.', 'Finkhousen, D.M.', 'Tepper, A.', 'Stevens, R.G.']

2021-10-19T15:27:10Z

2014

Mechanical Engineering

null

https://hdl.handle.net/2152/89299

eng

2014 International Solid Freeform Fabrication Symposium

Open

['crowdsourcing', 'collaborative engineering', 'additive manufacturing', 'GE', 'aircraft engine bracket']

The GE Aircraft Engine Bracket Challenge: An Experiment in Crowdsourcing for Mechanical Design Concepts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7f500f42-3fbb-4c90-9484-6a21a1d48063/download

University of Texas at Austin

An emerging international engineering design trend has resulted from widespread use of social media: a large number of people are engaged in collaborative engineering design activities to build their design expertise through interaction with other designers, to compete for recognition or prizes, or simply for the enjoyment of doing so. The term “crowdsourcing” was introduced in 2005 and implies soliciting contributions from a large group of people, usually an online community, in order to get a broad perspective from various points of view. This community-generated creativity is contrary to conventional practice in most manufacturing companies, which prefer tight control of engineering designs and practices because they represent key intellectual property and know-how. Recognizing that crowdsourcing represents a potential resource, GE embarked on an experiment to see how a for-profit company might benefit from soliciting new design approaches from this non-traditional source. The design of a specific part, an aircraft engine bracket, was released to an online community of engineers with an invitation to submit improved designs in an open competition. Entrants were encouraged to consider additive manufacturing as the fabrication method. Hundreds of designers submitted concepts and some achieved 80% reduction in weight.

null

['Jamalabad, Vikram R.', 'Whalen, Philip J.', 'Pollinger, John', 'Agarwala, Mukesh K', 'Danforth, Stephen C.']

2018-11-09T15:06:52Z

1996

Mechanical Engineering

doi:10.15781/T2ZP3WK5K

http://hdl.handle.net/2152/69923

eng

1996 International Solid Freeform Fabrication Symposium

Open

['Solid free-form fabrication', 'Molds', 'Gelcasting']

Gelcast Molding with Rapid Prototyped Fugitive Molds

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1b43c356-5845-431c-ba93-c4692a0a8cc0/download

null

A technique for the rapid manufacture ofceramic components has been developed using rapid prototyping to generate molds for the required components. The process entails the fabrication offugitive tooling using rapid prototyping techniques from which ceramic articles are formed using gelcasting. In the gelcasting process, the mold cavities are filled with a fluid suspension of ceramic powder which sets to a solid form through the polymerization of gelling additives and application of heat. The mold is carefully removed by dissolution or heat treatment leaving the intact gelcast part. The "green" gelcast part is subsequently dried and sintered to full density. Computer aided manufacturing of the tooling using solid freeform fabrication techniques allows for complex shapes to be manufactured with minimal tooling cost. The technique is idealfor the manufacture of ceramic parts in small batch conditions or for prototyping of functional parts in design cycles. Cost and time reduction of a magnitude can be achieved.

null

['Pan, Tan', 'Karnati, Sreekar', 'Liou, Frank']

2021-11-10T22:33:16Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90194', 'http://dx.doi.org/10.26153/tsw/17115']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['general rules', 'build process', 'process planning', 'powder bed fusion']

General Rules for Pre-Process Planning in Powder Bed Fusion System - A Review

Conference paper

https://repositories.lib.utexas.edu//bitstreams/888dc1ff-8be7-4c64-aa67-4e7cdcfcc2bb/download

University of Texas at Austin

Powder bed fusion (PBF) is one of the current additive manufacturing techniques that can fabricate almost fully dense functional metal components. Through a layer by layer fabrication methodology, complex geometries to meet the requirements of aerospace, automotive, biomedicine industries, etc. can be produced. The success of a build largely depends on having a flawless pre-process planning, including build orientation selection, support structure optimization, process parameter chosen, etc., which closely relates to the quality of the final products. Geometric inaccuracy and poor surface quality can occur due to a bad build plan. This review presents the crucial general planning rules for the build process. Build orientation selection, support structure optimization, and process parameter chosen in terms of residual stress reduction are the mainly concerns, which have been surveyed and discussed. The overall objective of this work is to help setup build plans that can ensure precise dimensions and high surface quality among the built components.

null

['Rock, Stephen J.', 'Wozny, Michael J.']

2018-04-19T18:25:51Z

1992

Mechanical Engineering

doi:10.15781/T2C53FJ2V

http://hdl.handle.net/2152/64406

eng

1992 International Solid Freeform Fabrication Symposium

Open

['STL de facto', 'CAD models', 'Computer aided designs']

Generating Topological Information from a "Bucket of Facets"

Conference paper

https://repositories.lib.utexas.edu//bitstreams/36f2a0f7-abb5-4a59-8ce4-930053e024b5/download

null

The STL de facto data exchange standard for Solid Freefonn F*brication represents CAD models as a collection of unordered triangular planar facels. No topological connectivity information is provided; hence the term "bucket of facet." Such topological information can, however, be quite useful for performing model validity checking and speeding subsequent processing operations such as model slicing. lfhis paper discusses model topology and how to derive it given a collection of unordered tri,ngular facets which represent a valid model.

null

['Porter, Conor', 'Carter, Fred', 'Kozjek, Dominik', 'Cardona, Andrea', 'Mogonye, Jon-Erik', 'Ehmann, Kornel', 'Cao, Jian']

2023-01-31T14:17:48Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117369', 'http://dx.doi.org/10.26153/tsw/44250']

eng

2022 International Solid Freeform Fabrication Symposium

Open

ALSI10MG L-PBF

Generation and Analysis of AlSi10Mg L-PBF Single Track Data Set Enabling Deeper Process Insights

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7ba6384b-9cdc-4474-a72e-5ef6ba6c1f91/download

null

The stability of the melt pool in Laser Powder Bed Fusion (L-PBF), especially with process perturbations, is a key factor underpinning the success of additively manufactured components. In metal Additive Manufacturing (AM), single tracks are widely used to verify and validate simulation and process models. This work describes the creation of a holistic L-PBF single track data set incorporating a large domain of process conditions for AlSi10Mg. The 352 single tracks are characterized through a series of high throughput methods including white light interferometry, automated microstructure analysis, and in-situ high-frequency (up to 200 kHz) coaxial melt pool monitoring. This data constitutes a large database of process parameters, high- resolution measurements, and geometry information for data driven analysis, including machine learning. In one approach this data is used to correlate track shape and melt pool characteristics to in-situ measurements.

null

['Rui, Wang', 'Haiou, Zhang', 'Guilan, Wang', 'Shangyong, Tang', 'Runsheng, Li']

2021-11-03T20:15:51Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89921

eng

2017 International Solid Freeform Fabrication Symposium

Open

['deposition path', 'deposition region', 'quadrilateral meshes']

Generation of Deposition Parts and Quadrilateral Meshes in Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1dedfef4-48e4-4bff-9009-82b997f2cde3/download

University of Texas at Austin

In wire arc welding Additive Manufacturing (WAAM), filling paths have a strong influence on the deformation of fabricated part. Many researchers employ FEM to analyze the effects of different filling strategies. However, they mainly majored in regular simple path (e.g. line and circle).This paper presents the method to generate meshes in deposition region of complicated path which can be used in FEM. First, the contour offset path and skeleton path is introduced. Then, the deposition region of each path is created by offsetting the paths inward and outward. Afterwards, quadrilateral meshes are constructed within each region. Deposition region is approximated by meshes.

null

['Neumeister, A.', 'Himmelhuber, R.', 'Temme, T.', 'Stute, U.']

2020-02-27T19:25:04Z

9/14/06

Mechanical Engineering

null

['https://hdl.handle.net/2152/80093', 'http://dx.doi.org/10.26153/tsw/7114']

eng

2006 International Solid Freeform Fabrication Symposium

Open

micro system technology

Generation of Micro Mechanical Devices Using Stereo Lithography

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c91948aa-26c1-41f3-8d43-40f59453cc30/download

null

A high resolution machining setup for creating three-dimensional precision components from a UV-curable photo-resin has been developed. By using frequency-converted diode-pumped solid state lasers, functional micro-mechanical devices are directly fabricated in a successive layer-bylayer fashion. Within this paper, the direct generation of micro assemblies having moving components without further assembly of parts will be presented. The micro system design is based on user-defined 3D-CAD data and will completively be built up within the fabrication cycle. By using specially developed μSL materials with suitable properties for micromechanical parts, the development from Rapid Prototyping towards Rapid Production of small series is intended.

null

['Bertoldi, M.', 'Yardimci, M. A', 'Pistor, C. M', 'Guceri, S.I', 'Danforth, S. C.']

2019-02-28T18:36:08Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73509', 'http://dx.doi.org/10.26153/tsw/659']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['SML', 'SSL']

Generation of Porous Structures Using Fused Deposition

Conference paper

https://repositories.lib.utexas.edu//bitstreams/14d84492-a977-42e4-9eea-bb10d0817568/download

null

The Fused Deposition Modeling process uses hardware and software machine-level language that are very similar to that of a pen-plotter. Consequently, the·use of patterns with poly-lines as basic geometric features, instead of the current method based on filled polygons (monolithic models), can increase its efficiency. In the current study, various toolpath planning methods have been developed to fabricate porous structures. Computational domain decomposition methods can be applied to the physical or to slice-level domains to generate structured and unstructured grids. Also, textures can be created using periodic tiling of the layer with unit cells (squares, honeycombs, etc). Methods 'based on curves include fractal space filling curves and.change of effective road width Within a layer or within a continuous curve. Individual phases can also be placed in binary compositions. In present investigation, a custom software has been developed and implemented to generate build files (SML) and slice files (SSL) for the above-mentioned structures, demonstrating the efficient control ofthe size, shape, and distribution ofporosity.

null

['Logozzo, Paula', 'Palomino, Donald', 'Meiszner, Abraham', 'Borijin, Bodia', 'Wang, Andrew', 'Watkins, Ryan', 'Li, Bingbing']

2023-02-24T14:41:09Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117523', 'http://dx.doi.org/10.26153/tsw/44403']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Generative Design', 'Design for Additive Manufacturing', 'Satellite Optical Tracker Mount']

Generative Design for Additive Manufacturing of Satellite Optical Tracker Mount

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ddba2f64-dfbd-41c3-aa38-8df3c11a004d/download

null

The organic and intricate nature of machine generated parts is problematic during the manufacturing phase, resulting in high costs and slow production with traditional manufacturing techniques. Additive manufacturing has been explored and approved as the potential solution for fabricating complex geometry and organic lattice structures. With the advances in topology optimization and generative design, design for additive manufacturing (DAM) allows users to generate numerous, high-quality design alternatives that are lighter and stronger than traditionally designed parts. This study addresses the process of designing and load testing a satellite optical instrument mounting bracket using the generative design and simulation capabilities of Autodesk Fusion 360. The workflow pipeline begins with the creation of generative design studies for the instrument bracket in accordance with the design criteria outlined in the optical instrument design challenge, where it is then thermally load tested using finite element analysis (FEA) in Fusion 360 and analyzed for its mechanical behavior.

null

Boivie, Klas

2019-11-21T18:45:50Z

2003

Mechanical Engineering

null

['https://hdl.handle.net/2152/78567', 'http://dx.doi.org/10.26153/tsw/5623']

eng

2003 International Solid Freeform Fabrication Symposium

Open

SLS Steel

A Generic System for Homogenous SLS Steel Materials

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9dc137f1-c0c9-428c-8622-bc3711b142de/download

null

A generic approach to a variety if different steel materials for SLS based application has been examined. This approach is based on a base steel alloy powder mixed with a powder blend of much smaller particles. The powder blend is designed to both provide the highest possible density in the powder mass and melting material components for liquid phase sintering to full density. Furthermore, the liquid phase components in the powder blend are composed to both serve as a metallic binder for the green bodies and maintain the possibility to completely dissolve into the base material, forming a homogenous alloy. A powder blend with stainless steel base material was composed and tested and taken through the different process steps. While the formation of green bodies had limited success, to a large extent due to limitations in the process equipment, the sintering and diffusion behaviour showed promising results, both in respect to acquired densities, and homogeneity of the material.

null

['Arumaikkannu, G.', 'Uma Maheshwaraa, N.', 'Gowri, S.']

2020-02-20T21:01:23Z

2005

Mechanical Engineering

null

https://hdl.handle.net/2152/80053

eng

2005 International Solid Freeform Fabrication Symposium

Open

Genetic Algorithm

A Genetic Algorithm with Design of Experiments Approach to Predict the Optimal Process Parameters for FDM

Conference paper

https://repositories.lib.utexas.edu//bitstreams/73a21b6e-bc8d-4bd1-88f4-bc63cc97d22d/download

null

This paper describes a Genetic Algorithm (GA) with Design of Experiments (DoE) approach to predict the optimized surface roughness and porosity characteristics of the parts produced using ABS material on stratasys FDM 2000 machine. The Mathematical Model (MM) was developed by using Response Surface Methodology (RSM). It is to predict and investigate the influence of selected process parameters namely slice thickness, road width, liquefier temperature and air gap and their interactions on the surface roughness and porosity. The developed MM is the fitness function in GA in order to find out the optimal sets of process parameters and to predict the corresponding surface quality characteristics. These results have been validated and the experimental results after GA are found to be in conformance with the predicted process parameters.

null

['Vaughan, D.M.', 'Meyer, L.', 'Masuo, C.', 'Nycz, A.', 'Noakes, M.W.', 'Vaughan, J.', 'Walters, A.', 'Carter, B.', 'Wallace, R.']

2023-04-03T17:34:56Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117725', 'http://dx.doi.org/10.26153/tsw/44604']

eng

2022 International Solid Freeform Fabrication Symposium

Open

DED

Geometric Challenges in Designing Parts for Machining using Wire-fed DED

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c55f0ffd-e5bd-41d6-ba9b-6c5bfdc7066a/download

null

Wire-fed DED using MIG welding systems allows for high deposition rates above 30lbs/hr, enabling much larger parts to be printed than would be possible on other DED systems. However, a drawback to this high deposition rate is a relatively low bead resolution on the printed part. Post-processing using machining is usually required on any mating surfaces printed using wire-fed DED. Problems such as residual stress in the build plate and printed part, underbuilding, and path interpolations can all lead to insufficient material deposition and deviation from the desired shape. These areas where the printed part varies from the model can leave defects on post-processed surfaces. This paper will cover common geometry issues that can arise from wire-fed DED and design changes that can be made to ensure that the printed design contains the required material to achieve the finished part.

null

['Chang, S.', 'Li, H.', 'Ostrout, N.', 'Jhuria, M.', 'Mottal, S.A.', 'Sigg, F.']

2021-10-21T19:47:57Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89433

eng

2015 International Solid Freeform Fabrication Symposium

Open

['3D printing', '3D printers', 'geometric element test targets', 'dimensional variability', 'geometric variability']

Geometric Element Test Targets for Visual Inference of a Printer's Dimension Limitations

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c3907aff-2c3f-4377-be3a-bcbfd842f5e2/download

University of Texas at Austin

As technologies advance in the field of additive manufacturing (AM), it increases the demand in using test targets to quantitatively appraise the performance of AM processes and parts. This study presents a unique concept to address the dimensional and geometric viability of threedimensional (3D) printers with test targets that are unique and complementary to those currently available. We have named these distinct designed artifacts as Geometric Element Test Targets (GETTs). The concept for the targets is to rely on positioning and spatial frequency of geometric shapes to induce failures that are indicative of the system’s dimensional limitations. A distinguishing characteristic is that the dimensional failures can be inspected visually. Systematic evaluations of the limitations can be further conducted through contact or non-contact measurements. The initial GETTs include three suites of test targets: line, angular and circular suites. We will illustrate this concept with samples produced with fused deposition modeling printers. The potential applications of GETTs include standardization, reference targets, in-line system control, and more.

null

['Gursoz, E. Levent', 'Weiss, Lee E.', 'Prinz, Fritz B.']

2018-04-10T19:25:46Z

1990

Mechanical Engineering

doi:10.15781/T2PC2TS21

http://hdl.handle.net/2152/64250

eng

1990 International Solid Freeform Fabrication Symposium

Open

['The Engineering Design Research Center', 'Rapid Tool Fabrication System', 'NOODLES']

Geometric Modeling for Rapid Prototyping and Tool Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/264ce5e8-7220-4dd8-996d-01d8c4341a61/download

null

This paper describes the application of a non-manifold geometric modeling environment, NOODLES, to a Rapid Tool Fabrication System. This system integrates stereolithography and thermal spray deposition into a CAD/CAM environment which includes design evaluation tools, robotic spraying, and computer-aided process planning. The level of integration and the number of different models in this system requires geometric representations that can be abstracted at several levels and that can be manipulated over several dimensions. The models in our framework for design, analysis, and fabrication share a single comlnon unifying geometric representation implemented in NOODLES.

null

['Knoop, F.', 'Schoeppner, V.']

2021-11-08T23:01:47Z

2017

Mechanical Engineering

null

['https://hdl.handle.net/2152/90069', 'http://dx.doi.org/10.26153/tsw/16990']

eng

2017 International Solid Freeform Fabrication Symposium

Open

['geometrical accuracy', 'holes', 'cylinders', 'fused deposition modeling']

Geometrical Accuracy of Holes and Cylinders Manufactured with Fused Deposition Modeling

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ed32b1a4-ecb9-449a-94c1-2bb85057dbe2/download

University of Texas at Austin

A widely used Additive Manufacturing (AM) technology is Fused Deposition Modeling (FDM) to create prototypes and end-use parts with close-to-production thermoplastics. For their use as a final product, it is necessary that additively manufactured parts strictly adhere to the geometrical requirements of the technical drawing. In this paper, the holes and cylinders of the cylindrical elements are investigated in terms of achievable geometrical accuracy. For this purpose, different test specimens that allow a measurement of inner and outer diameters from 3 to 80 mm were designed. All specimens were measured with a coordinate measuring machine (CMM) to evaluate deviations from the nominal dimension and form deviations. The measuring method includes a scanning of the surface to record the course of dimensional deviations over the diameter. Thus, it was possible to visualize how deviations on cylindrical elements manufactured in FDM occur. In order to counteract these deviations and to improve the dimensional accuracy, different shrink factors and filling patterns were investigated. Consequently, an improvement of the dimensional accuracy was achieved.

null

['Nettekoven, Alexander', 'Franken, Nicholas', 'Topcu, Ufuk']

2021-11-22T14:54:58Z

9/1/21

Mechanical Engineering

null

['https://hdl.handle.net/2152/90485', 'http://dx.doi.org/10.26153/tsw/17404']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['large-scale 3D printing', 'quantitative analysis', 'printing while flying']

Geometrical Analysis of Simple Contours Deposited by a 3D Printing Hexacopter

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5a175969-2bbf-4616-8749-58cdc24e4a5f/download

null

Current limitations in vertical and horizontal mobility for ground robots in 3D printing of medium to large-scale objects have recently led to the development of a 3D printing hexacopter testbed at the University of Texas at Austin. This testbed can fly to a desired location and deposit polylactic acid on flat surfaces. A previous study has shown the feasibility of this approach but has not yet quantified the testbed's printing capabilities. In this paper, we quantify the printing capabilities. We print square contours of different sizes and quantify the printed results based on their geometric dimensions. We also quantify the testbed's trajectory tracking to assess the testbed's positioning accuracy during printing. In quantifying the testbed, we lay the groundwork for using aerial robots in printing applications of medium to large-scale objects, such as concrete printing.

null

['Nettekoven, Alexander', 'Franken, Nicholas', 'Topcu, Ufuk']

2021-12-07T18:19:49Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90747', 'http://dx.doi.org/10.26153/tsw/17666']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['3D printing hexacopter', 'testbed', 'geometrical analysis', 'simple contours']

Geometrical Analysis of Simple Contours Deposited by a 3D Printing Hexacopter

Conference paper

https://repositories.lib.utexas.edu//bitstreams/77429b09-8f0b-405e-820d-78b973cc9b40/download

University of Texas at Austin

Current limitations in vertical and horizontal mobility for ground robots in 3D printing of medium to large-scale objects have recently led to the development of a 3D printing hexacopter testbed at the University of Texas at Austin. This testbed can fly to a desired location and deposit polylactic acid on flat surfaces. A previous study has shown the feasibility of this approach but has not yet quantified the testbed’s printing capabilities. In this paper, we quantify the printing capabilities. We print square contours of different sizes and quantify the printed results based on their geometric dimensions. We also quantify the testbed’s trajectory tracking to assess the testbed’s positioning accuracy during printing. In quantifying the testbed, we lay the groundwork for using aerial robots in printing applications of medium to large-scale objects, such as concrete printing.

null

['Lieneke, T.', 'Lammers, S.', 'Zimmer, D.']

2021-12-01T22:56:13Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90646', 'http://dx.doi.org/10.26153/tsw/17565']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'geometrical deviations', 'manufacturing accuracy']

Geometrical Deviations In Additive Manufacturing – Influences On The Manufacturing Accuracy

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5f750a34-7d39-4ed4-9f4f-26c02e84c3e8/download

University of Texas at Austin

The advantages of Additive Manufacturing (AM) highlight the capability to become an inherent part within the product development process. However, process specific challenges harm its further currency for industrial applications, for instance the high geometrical deviations. Different process factors influence the manufacturing accuracy and lead to large dimensional, form and positional deviations. Published research relative to deviations is difficult to compare, because it is based on several specimens that were manufactured with different processes, materials and machine settings. This fact emphasizes that reliable tolerance values for AM are hard to define in standards. Within this investigation, a universally applicable method was developed to examine geometrical deviations for AM processes. The main aim is the derivation of achievable tolerance values considering important influencing factors. Furthermore, due to the locally varying surface roughness of additively manufactured parts several tactile measurements were compared.

null

['Gervasi, Vito R.', 'Schneider, Adam', 'Rocholl, Joshua']

2020-02-14T16:16:12Z

2004

Mechanical Engineering

null

['https://hdl.handle.net/2152/79990', 'http://dx.doi.org/10.26153/tsw/7015']

eng

2004 International Solid Freeform Fabrication Symposium

Open

hybrid fabrication paths

Geometry and Procedure for Benchmarking SFF and Hybrid Fabrication Process Resolution

Conference paper

https://repositories.lib.utexas.edu//bitstreams/82a5b728-48ee-462b-b3bc-575e3b9fcf17/download

null

Since the advent of SFF and RP a number of SFF benchmarking geometries and methodologies have been developed and employed with some similarities but limited standardization. Minimal information has been published in regard to a standard method of measuring the resolution limits or capabilities of SFF and SFF-based hybrid processes. In an effort to benchmark resolution limits of SFF and Hybrid Fabrication processes, several benchmarking geometries were developed to capture the resolution capabilities, specifically hole size and rod size range, of multiple hybrid fabrication path steps and a hybrid path as a whole. These useful geometries are shared with the SFF community and procedures for their use are described in this paper.

null

['Sassaman, D.', 'Ide, M.', 'Beaman, J.', 'Seepersad, C.', 'Kovar, D.']

2021-12-06T21:25:58Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90676', 'http://dx.doi.org/10.26153/tsw/17595']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['geometry limitations', 'geometry', 'indirect selective laser sintering', 'alumina']

Geometry Limitations in Indirect Selective Laser Sintering of Alumina

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a5b396a9-26f5-41d1-a9ce-1f6b529e521c/download

University of Texas at Austin

Ceramics containing open channels with complex geometries can be manufactured by additive manufacturing (AM) and are of great interest in clean energy technologies. However, design limitations and guidelines for manufacturing these architectures with AM have not yet been established. In this work, we compare previously proposed geometry limitations for polymer selective laser sintering (SLS) to the geometries produced using indirect SLS in alumina. We focus on a subset of model shapes that are simple to produce and measure. We show that these rules provide a starting point for the design and manufacture of ceramic geometries using indirect SLS. However, there are additional considerations for AM of ceramics by indirect SLS that further limit the geometries that can be produced.

null

['Venkataramani, Ravi', 'Das, Suman', 'Beaman, Joseph']

2019-02-18T17:38:51Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73392', 'http://dx.doi.org/10.26153/tsw/544']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['Selective laser sintering', 'impermeable']

Geometry Processing for SLS/HIP

Conference paper

https://repositories.lib.utexas.edu//bitstreams/efc3c864-f02e-446f-8a2b-825435becad3/download

null

SLS/HIP is a new net shape manufacturing method that combines the strengths of direct selective laser sintering and hot isostatic pressing. Direct selective laser sintering is a rapid manufacturing technique that can produce high density metal parts of complex geornetry with an integral, gas iinpenneable skin. These parts can then be directly post-processed by containerless HIP. Sophisticated processing of the part geometry is required to facilitate the desired results from SLS/HIP. This paper presents geometry processing algorithms being developed for in-situ canning of SLS/HIP components. This research is funded by DARPA IONR contract NO00 14-95-C-0 139 titled "Low Cost Metal Processing Using SLS/HIP".

null

['Xing, Xiaodong', 'Yang, Li']

2021-10-21T20:47:30Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89443

eng

2015 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'research and development', 'R&D', 'China']

A Glance at the Recent Additive Manufacturing Research and Development in China

Conference paper

https://repositories.lib.utexas.edu//bitstreams/73852862-5562-4c35-8356-af8dbdf83edd/download

University of Texas at Austin

This paper reviews some of the recent additive manufacturing research and development works in China. A considerable amount of AM research activities in China focuses on directed energy deposition processes, powder bed fusion processes and stereolithography, with much of the effect dedicated to system and application development. Although many of the recent results are not readily available from the literatures published in China, from the available information the areas of focus for research and development could be clearly seen. Despite some speculations, the AM research in China is vibrate and aggressive, with some areas at least several years ahead of the other countries.

null

['Mitzner, Scott', 'Liu, Stephen', 'Domack, Marcia', 'Hafley, Robert']

2021-10-06T20:30:23Z

2012

Mechanical Engineering

null

['https://hdl.handle.net/2152/88435', 'http://dx.doi.org/10.26153/tsw/15372']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['Ti-6Al-4V alloy', 'grain refinement', 'electron beam', 'gas-tungsten arc', 'freeform fabrication']

Grain Refinement of Freeform Fabricated Ti-6Al-4V Alloy Using Beam/Arc Modulation

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d96ca489-7285-461f-9f07-cc6019d654a3/download

University of Texas at Austin

Grain refinement can significantly improve the mechanical properties of freeform-fabricated Ti6Al-4V alloy, promoting increased strength and enhanced isotropy compared with coarser grained material. Large β-grains can lead to a segregated microstructure, in regard to both αphase morphology and α-lath orientation. Beam modulation, which has been used in conventional fusion welding to promote grain refinement, is explored in this study for use in additive manufacturing processes including electron beam freeform fabrication (EBF3) and gas-tungsten arc (GTA) deposition to alter solidification behavior and produce a refined microstructure. The dynamic molten pool size, induced by beam modulation causes rapid heat flow variance and results in a more competitive grain growth environment, reducing grain size. Consequently, improved isotropy and strength can be achieved with relatively small adjustments to deposition parameters.

null

['Gupta, Sulabh', 'Rui, Rahul']

2021-10-19T15:23:57Z

2014

Mechanical Engineering

null

https://hdl.handle.net/2152/89298

eng

2014 International Solid Freeform Fabrication Symposium

Open

['3D printing', 'computational pipeline', 'large size 3D models', 'additive manufacturing']

A Graph Grammar Based Approach to 3D Print and Assemble Furniture

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7416d7ee-f51b-4116-bfa4-99437c93631f/download

University of Texas at Austin

A Plethora of user generated 3D models are available online. With rapid proliferation and diffusion of additive manufacturing machines in households, it has now become possible to download these virtual objects and print them out as physical parts. Although printing small size parts (within print volume of low cost 3D printers) is relatively an easy task, additive fabrication of large size parts (part volumes greater than print volume of low cost 3D printer) remains a challenging task for novice 3D printer users. In this paper the authors present a computational pipeline to 3D print large size 3D models that can be easily downloaded from online websites. The pipeline essentially enables decomposition of large objects into smaller parts that can be 3D printed and then assembled. To assemble the printed parts a three-pronged approach is outlined. First, an interface based on graph grammar rules has been developed to generate assembly instructions. Second, an interactive segmentation of the desired 3D model is carried out using a Segmentation Guide Interface (SGI). SGI has been developed to assist a user to carry out component to sub-component segmentation. Third, we have also developed an interface that aids a user in printing small size pieces that can be printed in print volume of a commercial 3D printer (such as Makerbot®) and then assembled to create components that are too large to be printed in print volumes of low cost 3D printers. We demonstrate the efficacy of developed pipeline by creating assembly instructions for multiple large sized 3D table models available online.

null

['Rosen, David W.', 'Schaefer, Dirk', 'Scrage, Daniel']

2021-10-05T15:41:31Z

2012

Mechanical Engineering

null

['https://hdl.handle.net/2152/88394', 'http://dx.doi.org/10.26153/tsw/15333']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['Defense Advanced Research Projects Agency', 'MENTOR', 'Georgia Tech', 'high school education program', 'system engineering', 'additive manufacturing']

GT ME TOR: A High School Education Program in Systems Engineering and Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b24454d0-4e1e-4c32-a675-a7f43079216e/download

University of Texas at Austin

The Defense Advanced Research Projects Agency (DARPA) is sponsoring the MENTOR program as the outreach part of its Adaptive Vehicle Make suite of programs. Georgia Tech has been awarded a contract to involve up to 1000 high schools after 4 years in a series of prize challenges. A web-based collaborative design-manufacturing infrastructure will be developed that integrates CAD, CAE, design-for-manufacturing, and CAM software tools with a network of 3D printers and other manufacturing resources. In distributed teams, students will design, fabricate, and construct electro-mechanical systems (e.g., ground vehicle robots) to perform complex tasks. Many parts they design will be fabricated on 3D printers that are located in high schools or nearby sites. A project objective is to have students learn about collaborative design, advanced manufacturing, and new product development practices and to become excited about pursuing technology-based careers.

null

['Luben, Hannah', 'Meisel, Nicholas']

2024-03-27T15:40:42Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124485', 'https://doi.org/10.26153/tsw/51093']

en

2023 International Solid Freeform Fabrication Symposium

Open

['design for additive manufacturing', 'topology optimization', 'legacy tooling']

GUIDED MANUAL DESIGN FOR ADDITIVE MANUFACTURING OF TOPOLOGICALLY OPTIMIZED LEGACY TOOLING PARTS

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9ee56e17-4dde-4814-b245-ee1c5d1285b8/download

University of Texas at Austin

Design for Additive Manufacturing (DfAM) is a unique conceptual way to adapt a part for Additive Manufacturing (AM). While some of the choices made in DfAM become second nature to seasoned AM designers, inexperienced designers may not know the nuances involved in what is still a developing manufacturing technology. Topology Optimization (TO) in particular tends to create organic shapes that may not be immediately conducive to printing through AM. This paper proposes a comprehensive workflow tool to guide a designer, regardless of their experience, through the decision-making process inherent to DfAM. The guide helps the designer manually edit a legacy tooling design into a topologically optimized part that is readily manufacturable through AM. Discussion of a relevant case study follows the outline of the design tool to exemplify its use.

null

['Neitzel, F.', 'Kletetzka, I.', 'Schmid, H.-J.']

2024-03-25T22:20:11Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124318', 'https://doi.org/10.26153/tsw/50926']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['PBF-LB/P', 'PA12', 'halogen', 'flammability', 'additive manufacturing']

HALOGEN-FREE FLAME-RETARDANT POWDER MATERIALS FOR LASER SINTERING: EVALUATION AND PROCESS STABILITY ANALYSIS

Conference paper

https://repositories.lib.utexas.edu//bitstreams/22c94920-6571-4d07-8c16-f1bb3300a064/download

University of Texas at Austin

The high flammability of components manufactured by laser-based powder bed fusion of plastics (PBF-LB/P) using standard polyamide 12 (PA12) powder still severely restricts their use in industries such as electronics, aviation, and transportation. A key factor for the further establishment of PBF-LB/P is the expansion of the material portfolio with, for example, refreshable and halogen-free flame-retardant (FR) powder materials. Accordingly, various halogen-free FRs are investigated in this work and evaluated with respect to their use in PBF-LB/P. First, their decomposition behavior and mode of action are examined. Subsequently, the additives are dry blended with PA12 to investigate properties relevant for PBF-LB/P, such as particle morphology, thermal behavior, and melt viscosity. Afterwards, test specimens for UL94 vertical flame-retardancy tests are produced by processing the dry blends on an EOS P3 PBF-LB/P system. Finally, the process stability of the process-aged powder blends is investigated by again examining thermal behavior and melt viscosity.

null

['Monnier, L.V.', 'Ko, H.']

2023-04-03T17:43:17Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117728', 'http://dx.doi.org/10.26153/tsw/44607']

eng

2022 International Solid Freeform Fabrication Symposium

Open

Additive manufacturing

HDF5 Hierarchies for Additive Manufacturing digital representations and Enhanced Analytics

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b3b83ce5-eed0-4987-80d9-813387db54fc/download

null

Advancement in Additive Manufacturing (AM) technologies and data acquisition techniques have led to an increase in AM data generated. However, due to the large volume and the diversity of AM data available it is becoming challenging to eﬃciently store, analyze, and represent AM processes. HDF5 has the potential to allow an easy access to big data by oﬀering a hierarchical data catalog. Thus, AM processes could be represented through a hierarchy based on the data analytic needs and directly link the corresponding AM data. This paper investigates the use of data formats to represent big data and AM dataset. Existing AM ontologies and models are reviewed in order to eﬀectively encapsulate AM information and incorporate the hierarchy into an HDF5 AM wrapper. Three hierarchies are proposed to represent speciﬁc perspectives of AM processes: the digital twin of AM Product Lifecycle, the AM V model representation, and the material centric characteristics.

null

['Duty, Chad E.', 'Fuhrman, Brian T.', 'Jean, Daniel L.', 'Lackey, W. Jack']

2019-09-23T17:03:29Z

2000

Mechanical Engineering

null

['https://hdl.handle.net/2152/75973', 'http://dx.doi.org/10.26153/tsw/3072']

eng

2000 International Solid Freeform Fabrication Symposium

Open

Deposition

Heat Transfer Analysis of a Gas-Jet Laser Chemical Vapor Deposition (LCVD) Process 461

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1ae8f3c0-4241-4086-9636-ad7bfde89528/download

null

This paper describes the development of a computer model used to characterize the heat transfer properties of a gas-jet LCVD process. A commercial software package was used to combine heat transfer finite element analysis with the capabilities of computational fluid dynamic software (CFDS). Such a model is able to account for both conduction and forced convection modes of heat transfer. The maximum substrate temperature was studied as a function of laser power and gas-jet velocity.

null

['Michaelis, Matthew', 'Zhu, Jun', 'Orme, Melissa']

2019-10-24T17:49:13Z

2002

Mechanical Engineering

null

['https://hdl.handle.net/2152/77407', 'http://dx.doi.org/10.26153/tsw/4496']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Manipulation

Heat Transfer Manipulation for Precision Droplet Manufacturing: Simulation and Experiment

Conference paper

https://repositories.lib.utexas.edu//bitstreams/234d56d7-e594-4612-92b8-d8cf185b53f9/download

null

The solid free-form fabrication (SFF) of arbitrary metallic components is accomplished with controlled deposition of nano-liter molten droplets generated by capillary stream break-up and deposited at rates on the order of 10,000 drops/second. By varying the droplet arrival temperature, deposition rate, and substrate temperature in both the simulation and experiment, we seek to obtain a thorough understanding of the heat transfer phenomena that governs the SFF component quality. Of specific interest is the removal of inter-splat boundaries in order to achieve a high quality component, characterized by a uniform and fine microstructure, by having newly arriving drops remelt a thin layer of the previously deposited and solidified material. A numerical model, which simulates the heat transfer manipulation, is used to understand and guide the process development.

We gratefully acknowledge the generous funding from the National Science Foundation, grant number DMI-0070053, "High-Speed Droplet-Based Manufacturing of High-Precision Structural Components and Photonic BandGap Materials."

null

['Saiz, Natalia', 'Pegues, Jonathan', 'Whetten, Shaun', 'Kustas, Andrew', 'Chilson, Tyler']

2023-01-27T17:48:50Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117346', 'http://dx.doi.org/10.26153/tsw/44227']

eng

2022 International Solid Freeform Fabrication Symposium

Open

Ti-6Al-4V

Heat Treatment Effects on Mechanical Properties of Wire Arc Additive Manufactured Ti-6Al-4V

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f6739a44-85b0-4e5f-91cc-b681247cddb7/download

null

Directed energy deposition (DED) is an attractive additive manufacturing (AM) process for large structural components. The rapid solidification and layer-by-layer process associated with DED results in non-ideal microstructures, such as large grains with strong crystallographic textures, resulting in severe anisotropy and low ductility. Despite these challenges, DED has been identified as a potential solution for the manufacturing of near net shape Ti-6Al-4V preforms. In this work, we explore several heat treatment processes, and their effects on tensile properties of wire arc additively manufactured (WAAM) Ti-6Al-4V. A high throughput tensile testing procedure was utilized to generate statistically relevant data sets related to each specific heat treatment and sample orientation. Results are discussed in the context of microstructural evolution and the resulting fracture behavior for each condition as compared to conventionally processed Ti-6Al-4V.

null

['Ma, Xulong', 'Lin, Feng', 'Zhang, Lei']

2021-10-19T18:29:40Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89319

eng

2014 International Solid Freeform Fabrication Symposium

Open

['binder jetting additive manufacturing', 'building error', 'binder infiltration', 'powder bed', 'heterogeneous compensation']

The Heterogeneous Compensation for the Infiltrative Error of the Binder Jetting Additive Manufacturing Processes

Conference paper

https://repositories.lib.utexas.edu//bitstreams/54b04e79-3b68-4ee3-9a6a-0f707348e53b/download

University of Texas at Austin

In binder jetting additive manufacturing, such as Three Dimensional Printing (3DP) and Patternless Casting Manufacturing (PCM, a process similar as ExOne and VoxelJet), the building error is mainly caused by the infiltration by the binder in the powder bed, and appear heterogeneous magnitude along different orientations because of the different infiltrating depth of the printed binder between the building direction and the binder printing direction. Current methods to compensating these error are mostly based on the contour equidistant offset and the model shrinkage, which couldn’t deal with the heterogeneous infiltrative error. In this paper, we will propose a novel compensation method, in which the STL model will be counteracted heterogeneously in different directions to compensate the heterogeneous infiltrative distances of the binder in the powder. By this method, a sphere STL model will be transferred into an ellipsoid with variant axis length along different X/Y/Z directions. The method could greatly improve the dimensional accuracy of a series of additive manufacturing techniques which are based on the binder jetting onto powder bed.

null

['Biswas, Arpan', 'Shapiro, Vadim', 'Tsukanov, Igor']

2019-10-23T15:25:12Z

2002

Mechanical Engineering

null

['https://hdl.handle.net/2152/76761', 'http://dx.doi.org/10.26153/tsw/3850']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Material Modeling

Heterogeneous Material Modeling with Distance Fields

Conference paper

https://repositories.lib.utexas.edu//bitstreams/cd2f6678-2e3d-4da3-a1f7-b7932d3d5beb/download

null

We propose a universal approach to the outstanding problem of computer modeling of continuously varying distributions of material properties satisfying prescribed material quantities and rates on a finite collection of geometric features. The central notion is a parameterization of the shape’s interior by distances from the material features - either exactly or approximately; this parameterization supports specification, interpolation, and optimization of desired material distributions in a systematic and controlled fashion. We demonstrate how the approach can be implemented within the existing framework of solid modeling and its numerous advantages, including: • precise and intuitive control using explicit, analytic, differential, and integral constraints specified on the original (not discretized) geometric model; • applicability to material features of arbitrary dimension, shape, and topology; and • guaranteed smoothness and analytic properties for superior performance, analysis and optimization. Last, but not least, the proposed approach subsumes and generalizes a number of other proposals for heterogeneous material modeling for FGM, heterogeneous solid modeling, and solid free-form fabrication.

null

['Morvan, Stephane M.', 'Fadel, Georges M.']

2019-03-12T16:30:28Z

1999

Mechanical Engineering

null

['https://hdl.handle.net/2152/73597', 'http://dx.doi.org/10.26153/tsw/739']

eng

1999 International Solid Freeform Fabrication Symposium

Open

['Rapid Prototyping', 'Solid freeform fabrication']

Heterogeneous Solids: Possible Representation Schemes

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3366785d-cdf9-415d-bac9-fc306adc6bf9/download

null

Solid freeform fabrication processes allow parts to be built with accuracy and mechanical integrity, permittingthem to be used in tooling or fOrlnandfit applications. There is already a need form~lti ..color Parts.for surgical applications, which will eventually lead to. multi-material RP .machines.WhetherJor on the spot color deposition or for functionally tailored multiple materials parts,.RPmachines with such capabilities are becoming available. They will eventually lead to the trtiepromise of Solid Freeform Fabrication: a system that can build a functional mechanism without assembly, and from multiple materials. This paper is aimed at understanding the new challenges raised from representing solids whose material distribution is changing gradually from one material to another (HC), and those made of a collection .of discrete materials (HD). Several representation schemes are reviewed and critiqued. Techniques borrowed from medical imaging and geoscience modeling are used to better understand the modeling of heterogeneous and gradient solids, from a geometric standpoint.

null

['Roh, Byeong-Min', 'Yang, Hui', 'Simpson, Timothy W.', 'Jones, Albert T.', 'Witherell, Paul']

2023-01-27T13:53:05Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117332', 'http://dx.doi.org/10.26153/tsw/44213']

eng

2022 International Solid Freeform Fabrication Symposium

Open

Additive manufacturing

A Hierarchical V-Network Framework for Part Qualification in Metal Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/be0968d4-c962-4b6e-a14f-59cb9b26b6fb/download

null

Advances in metal additive manufacturing (AM) technologies have enabled greater design freedoms than subtractive manufacturing has afforded. The design freedoms and flexibilities offered by a metal AM system, however, dramatically increase process uncertainties that may also increase part-quality variabilities. Any metal AM part must be tested, validated, and verified to meet quality, safety, and performance requirements. Common qualification methodologies rely on destructive testing, which is neither cost-effective nor efficient. Much research, which has been conducted on sensing-based, part qualification in AM systems, attempts to maximize the reduction of destructive testing by closely monitoring the fabrication process in real-time. So much “big data” is generated by this increased use of sensors and available measurement sources. However, the use of the data is still hindered by 1) scale & size and 2) uniformity. We propose a hierarchical, V-network framework of quality assurance with the corresponding translation from ex-situ to in-situ part qualifications. This framework offers an innovative, Cyber-Physical System (CPS) that accurately ties models, processes, and measurements together to interpret the sensor data. The framework also supports and guides translation from ex-situ to in-situ quality measurements, thereby providing a systematic structure and focusing on interrelationships between key observations that influence AM part quality. Ultimately the sensor data can support the detection of process anomalies, thus providing a more streamlined and more efficient qualification process than is otherwise possible.

null

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

2021-09-30T19:29:27Z

2010

Mechanical Engineering

null

['https://hdl.handle.net/2152/88285', 'http://dx.doi.org/10.26153/tsw/15226']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['laser sintering', 'CAD model', 'model microstructure', 'mechanical properties', 'hierarchical modeling method', 'porosity', 'laser irradiance', 'image processing', 'computational materials design']

A Hierarchical, Heterogeneous Material CAD Model with Application to Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b358115b-d080-43a8-a028-dc08747c644c/download

University of Texas at Austin

Variations in laser irradiance and local temperatures in laser sintering cause variations in porosity and material microstructure, which can affect mechanical properties of a part. From the design perspective, it is important to model microstructures, mechanical properties, and their relationships so that parts can be analyzed and designed taking into account their as-manufactured condition. In this paper, we propose the modeling of part geometry and microstructure by using a new hierarchical modeling method. A surfacelet transform is introduced to model microstructure. The application of image processing methods enables multi-resolution representations of microstructure. Combined with methods from computational materials design, low resolution microstructure representations can be used to compute effective mechanical properties. The models and methods are demonstrated on two examples, a simple fiber-reinforced composite and a laser sintered nylon-12 material.

null

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

2020-02-28T15:34:15Z

9/14/06

Mechanical Engineering

null

['https://hdl.handle.net/2152/80111', 'http://dx.doi.org/10.26153/tsw/7132']

eng

2006 International Solid Freeform Fabrication Symposium

Open

Selective Laser Melting

High Density Selective Laser Melting of Waspaloy®

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0f561027-8007-4886-970d-5975f7585cba/download

null

In this work, high density Waspaloy® specimens were produced using specially assembled laboratory equipment by Selective Laser Melting (SLM). SLM of Waspaloy® powder was performed using a high power pulsed Nd:YAG laser. The laser parameters pulse energy (J), pulse width (ms), repetition rate (Hz) and scan speed (mm/min) were varied. Process parameter optimization was achieved using factorial analysis to investigate the relationship between specific processing parameters and the formation of Waspaloy® specimens. The optimized processing parameters produced Waspaloy® specimens that were 99.3 % dense. The resultant laser melted specimen’s height, width and contact angles were measured. Specimens were also observed for the occurrence of porosity.

null

['Kong, Chang-Jing', 'Tuck, Christopher J.', 'Ashcroft, Ian A.', 'Wildman, Ricky D.', 'Hague, Richard']

2021-10-05T13:42:56Z

8/17/11

Mechanical Engineering

null

['https://hdl.handle.net/2152/88370', 'http://dx.doi.org/10.26153/tsw/15309']

eng

2011 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', 'Ti6Al4V', 'density', 'material properties']

High Density Ti6Al4V via Slim Processing: Microstructure and Mechanical Properties

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ca44fe45-e625-4e0c-bba1-db5bc94b758c/download

University of Texas at Austin

This paper investigates a density improvement method for Ti6Al4V alloy processed by the selective laser melting method. A modified inert gas inlet baffle has been employed to develop improved mechanical properties for these materials. Comparisons of the top surface and cross-section porosities of solid blocks processed by the original and modified gas inlet baffles indicate that the modified baffle greatly increases the properties of the processing blocks. Results showed that the porosity of the Ti6Al4V alloy was lower than 0.1% by area. The microstructure of the SLM Ti6Al4V alloy exhibited martensitic α' phase. The UTS tensile strength was 920-960MPa and the elongation at the fracture was 3-5%. The fracture surfaces of the tensile samples demonstrated a mixture of ductile and brittle fracture.

null

['Karthik, N.V.', 'Gu, Hengfeng', 'Pal, Deepankar', 'Starr, Thomas', 'Stucker, Brent']

2021-10-07T18:25:34Z

2013

Mechanical Engineering

null

['https://hdl.handle.net/2152/88500', 'http://dx.doi.org/10.26153/tsw/15434']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['ultrasonic consolidation', 'ultrasonic testing', 'additive manufacturing', 'non-destructive analysis', 'non-destructive testing']

High Frequency Ultrasonic Non Destructive Evaluation of Additively Manufactured Components

Conference paper

https://repositories.lib.utexas.edu//bitstreams/90e0ef0b-6818-4931-a0be-35d711b1128e/download

University of Texas at Austin

Ultrasonic testing of additively manufactured components is useful for non-destructive defect analysis such as porosity, void and delamination detection as well as for analysis of material properties such as density, material strength and Young’s modulus. A high frequency ultrasonic system has been set up on a Fabrisonics Ultrasonic Additive Manufacturing (Ultrasonic Consolidation) machine to measure the material properties after each layer. The same system is also used to perform offline tests of parts fabricated by SLM. Traditional material analysis carried out using SEM and optical microscopy is used to validate and demonstrate the effectiveness of the non-destructive testing equipment.

null

['Grau, Jason', 'Moon, Jooho', 'Uhland, Scott', 'Cima, Michael', 'Sachs, Emanuel']

2018-12-05T17:43:19Z

1997

Mechanical Engineering

doi:10.15781/T2DV1D80B

http://hdl.handle.net/2152/71403

eng

1997 International Solid Freeform Fabrication Symposium

Open

['3DP', 'silicon nitride']

High green density ceramic components fabricated by the slurry-based 3DP process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6f7b249f-e001-4012-9a20-a7cb0f2d281b/download

null

The 3DP process has been modified to directly fabricate high green density parts using submicron powder. The slurry-based 3DP process deposits the powder bed by spraying a dispersed slurry of the component material onto a piston. Alumina, silicon nitride, and lead zirconate titanate components with green densities as high as 67% have been fabricated by the slurry-based 3DP process. Solution phase binder systems have proven to be successful for the new process. Substantially improved surface finish over the conventional dry powder-based 3DP process has been demonstrated. Layer heights less than 50 Jlm can be prepared with this process. Thus, the stepped surface topography commonly observed in solid free form parts is substantially reduced.

null

['Schleifenbaum, J.H.', 'Theis, J.', 'Meiners, W.', 'Wissenbach, K.', 'Diatlov, A.', 'Bültmann, J.', 'Voswinckel, H.']

2021-09-30T13:56:23Z

9/23/10

Mechanical Engineering

null

['https://hdl.handle.net/2152/88252', 'http://dx.doi.org/10.26153/tsw/15193']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['High Power Selective Laser Melting', 'series production', 'additive metal manufacturing', 'kW laser', 'optical multi-beam system']

High Power Selective Laser Melting (HP SLM) - Upscaling the Productivity of Additive Metal Manufacturing towards Factor 10

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a310d698-ab66-49b1-b0b7-c22b11c446d6/download

University of Texas at Austin

World market competition boosts trends like mass customization and open innovation which result in a demand for highly individualized products at costs matching of beating those of mass production. One of the manufacturing technologies with greatest potential to meet those demands is Selective Laser Melting (SLM) due to its almost infinite freedom of design and the provision of series-identical mechanical properties without the need for part-specific tooling, downstream sintering process, etc. However, the state-of-the-art productivity is not yet suited for series production. Hence, a new machine prototype including a kW laser and an optical multi-beam system is developed and set up. Experimental findings and first applications demonstrate the capability of the new system.

null

['Maxwell, James', 'Krishnan, Ramnath', 'Haridas, Suresh']

2018-12-06T20:57:18Z

1997

Mechanical Engineering

doi:10.15781/T2FN11C49

http://hdl.handle.net/2152/71427

eng

1997 International Solid Freeform Fabrication Symposium

Open

['SFF', 'HPCE-LCVD']

High Pressure, Convectively-Enhanced Laser Chemical Vapor Deposition of Titanium

Conference paper

https://repositories.lib.utexas.edu//bitstreams/eb856ada-98a4-4ab7-a151-418985466c9e/download

null

Laser chemical vapor deposition is a freeform technique that can generate three-dimensional structures from organometallic or metal halide precursors. To obtain enhanced growth rates, a novel high pressure reactor has been constructed where impinging jets of volatile fluids are heatedand pyrolyzed to create parts. Argon Ion and Nd:YAG lasers have been used to selectively generate three-dimensional titanium shapes from titanium tetrachloride, titanium tetrabromide, and titanium tetraiodide, at pressures up to 3.0 atmospheres. Emission lines characteristic ofthe reaction rate have been identified which will allow feedback control ofthe reaction rate. The process is being optimized to obtain high deposition rates, energy efficiency, and desirable material morphologies. A feedback control system is required to generate 3-D structures with dimensional accuracy and predictable deposition rates.

null

['Da, Cheng', 'Qi, Gang', 'Rangarajan, Sriram', 'Wu, Suxing', 'Langrana, Noshir A.', 'Safari, Ahmad', 'Danforth, Stephen C.']

2018-12-05T20:08:18Z

1997

Mechanical Engineering

doi:10.15781/T2NC5SZ73

http://hdl.handle.net/2152/71409

eng

1997 International Solid Freeform Fabrication Symposium

Open

['SFF', 'CAD']

High Quality, Fully Dense Ceramic Components Manufactured Using Fused Deposition of Ceramics (FDC)

Conference paper

https://repositories.lib.utexas.edu//bitstreams/42e4d685-2642-4934-96b5-e570a4d7a934/download

null

Solid Freeform Fabrication (SFF) is a technology that produces physical solid components or parts from computer design models. This technology has the potential of reducing functional ceramic product development cycle time in terms of reducing design iteration and production time, minimizing extra post processing, and therefore reducing cost. A commercially available Fused Deposition Modeling (FDM™) 3D Modeler was altered for use with ceramics. This newly developed method referred to as Fused Deposition of Ceramics (FDC) is capable of fabricating complex shape, functional ceramic components. We have investigated issues related to hardware, software, feed material, and build strategy which are required to achieve high quality, fully dense green ceramic parts. In this paper, we report recent improvements made in the FDC process, including hardware modifications, software improvements, feed material standardization, as well as build strategy/condition control. We also report the current FDC status for making complex functional parts. Our goal is to optimize the FDC condition to ensure its robustness for producing defect free green ceramic parts consistently and without interruption.

null

['Streek, A.', 'Regenfuss, P.', 'Exner, H.']

2021-10-12T22:39:47Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88759', 'http://dx.doi.org/10.26153/tsw/15693']

ara

2014 International Solid Freeform Fabrication Symposium

Open

['laser micro sintering', 'metals', 'additive manufacturing', 'powder', 'density']

High Resolution Laser Melting with Brilliant Radiation

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1e307496-ec5b-40e4-95c6-3b4750e0a4f2/download

University of Texas at Austin

Since the discovery of selective laser sintering/melting, numerous modifications have been made to upgrade or customize this technology for industrial purposes. Laser micro sintering (LMS) is one of those modifications: Powders with particles in the range of a few micrometers are used to obtain products with highly resolved structures. Pulses of a q-switched laser had been considered necessary in order to generate sinter layers from these µm-scaled metal powders. However, despite the high resolution, the process repeatability of LMS and the material property of the products have never been completely satisfactory. Recent technological and theoretical progress and the application of brilliant continuous laser radiation have now allowed for efficient laser melting of µm-scaled metal powders. Thereby, it is remarkable that thin sinter layers are generated with a very high laser power. The resulting product resolution is comparable to the one achieved by the LMS regime with q-switched pulses. From the experimental results the performance and potential of this high resolution laser melting regime is demonstrated and the limits of the applicable parameters are deduced.

null

['Abdi, M.', 'Ashcroft, I.', 'Wildman, R.']

2021-10-18T22:41:10Z

2014

Mechanical Engineering

null

https://hdl.handle.net/2152/89278

eng

2014 International Solid Freeform Fabrication Symposium

Open

['topology optimization', 'Finite Element Method', 'Extended Finite Element Method', 'Iso-XFEM']

High Resolution Topology Design with Iso-XFEM

Conference paper

https://repositories.lib.utexas.edu//bitstreams/585d5ee9-4e26-4c00-8589-99c4a64de180/download

University of Texas at Austin

Topology optimization, as a challenging aspect of structural optimization, has gained interest in recent years as a method of designing structures to take advantage of the design freedoms of advanced manufacturing techniques such as Additive Manufacturing (AM). The majority of topology optimization algorithms are integrated with the Finite Element Method (FEM) to enable the analysis of structures with complex geometry during the optimization process. However, due to the finite element-based nature of the subsequent topology optimized solutions, the design boundaries are dependent on the finite element mesh used and tend not to have the desired smoothness for direct fabrication. The topology optimized solutions may, therefore, need smoothing, reanalysing and shape optimization before they become manufacturable. In this study, an Extended Finite Element Method (X-FEM) is employed and integrated with an evolutionary structural optimization algorithm, aiming to avoid/decrease the post-processing required from topology optimization design to manufacture. Rather than using finite elements for boundary representation, an isoline/isosurface approach is used to capture the design boundary during the optimization process. The comparison of the X-FEM-based solutions with the FE-based ones for the topology optimization of test cases representing real industrial components indicates significant improvements in the solutions’ boundary representation as well as their structural performance.

null

['Hopkinson, Neil', 'Erasenthiran, Poonjolai']

2020-02-13T20:07:19Z

2004

Mechanical Engineering

null

['https://hdl.handle.net/2152/79973', 'http://dx.doi.org/10.26153/tsw/6998']

eng

2004 International Solid Freeform Fabrication Symposium

Open

Rapid Manufacturing

High Speed Sintering - Early Research into a New Rapid Manufacturing Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c4fc6b7e-9cbc-4f06-a72f-e1e5d1dc2053/download

null

Rapid Manufacturing (the production of end use products by layer manufacturing techniques) has grown significantly in recent years and has started to revolutionise some areas of manufacturing. Among the main drawbacks for commercially available techniques are machine cost and build speed. This paper describes some initial research into a new process called High Speed Sintering. The High Speed Sintering process (UK patent No. 0317387.9) involves the sintering of 2D profiles of layers of powder without the need for a laser. Experiments performed on a simple lab apparatus have shown how the addition of carbon black to standard nylon powder can increase the rate of sintering such that an entire layer may be sintered in 5 seconds using an infra-red lamp. The effects of composition of carbon black on material properties are shown and may be traded off against build speed. Thermal control of the process is vital and the effects of altering the position and power used with an infra-red lamp are presented. Eliminating a laser reduces machine cost and build time, combining these factors will make the High Speed Sintering process suitable for high volume manufacture. Cost predictions show that the process will be viable for the manufacture of standard products in volumes over 100,000.

null

['Thomas, Helen R.', 'Hopkinson, Neil', 'Erasenthiran, Poonjolai']

2020-03-05T19:54:12Z

2006

Mechanical Engineering

null

['https://hdl.handle.net/2152/80151', 'http://dx.doi.org/10.26153/tsw/7172']

eng

2006 International Solid Freeform Fabrication Symposium

Open

High Speed Sintering

High Speed Sintering – Continuing Research into a New Rapid Manufacturing Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/340d7027-d2ee-41f1-9f1b-7c75f35a2241/download

null

High Speed Sintering (HSS) is an emerging layer manufacturing technique aiming to break into the lucrative field of Rapid Manufacturing (RM). The process is likened to Selective Laser Sintering (SLS), however, instead of a laser dictating the sintered cross sectional area of each layer, the desired area is first printed using a Radiation Absorbing Material (RAM) and then sintered using an inexpensive infrared lamp. This paper begins by describing the sintering process in more detail and then outlining the overall manufacturing cycle. It then continues by describing the experiments performed to investigate the current problem concerning the hardness of excess powder within the powder bed. This problem arose due to the continual exposure of the whole bed to infrared radiation from the lamp. The experiments showed that as the power of the IR lamp increased, the hardness of the bed also increased. Furthermore, at higher IR power levels it was found the excess powder produced a solid tile which could only be broken down by a glass bead blaster.

null

['Yamazawa, Kenji', 'Niino, Toshiki', 'Hayano, Seiji', 'Nakagawa, Takeo']

2018-11-29T21:06:38Z

1997

Mechanical Engineering

doi:10.15781/T2M03ZH3J

http://hdl.handle.net/2152/70345

eng

1997 International Solid Freeform Fabrication Symposium

Open

['laser optical', 'overflow method']

High Speed UV Laser Beam Scanning by Polygon Mirror

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ed73fa36-8d5d-4c52-97b4-b38ccd2951ba/download

null

Since the stereolithograpy system appeared on the market, various rapid prototyping machines based on the layer laminated manufacturing process have emerged one after the other, the range of applications of which is classified according to their features. Of these, stereolithogrraphy methods which make use ofphotocurable resin as material and laser beam as processing tools are gradually being established. They are currently the most widespread with a rich variety of models available. The scanning device used in stereolithography serves as the key technology for this method but consists basically of only the galvanometer mirror known for outstanding high speed ability and the XY plotter known for outstanding scanning position accuracy1),2). Lately, many models are seen to use the galvanometer mirror due to improved accuracy, but still this scanning device is used only when the fabrication size allows, etc. From such reasons, the authors have developed a laser stereolithograpy system capable of high speed high accuracy position scanning by the high speed raster scanning method using a polygon mirror as the scanning device3). The polygon mirror, which has a higher scanning speed than the galvanometer mirror, is moved along the NC servo shaft and the raster scanning spacing is made considerably smaller than the laser beam spot diameter. This paper describes this system and the results offabrication experiments with this system.

null

['Vanmunster, L.', 'Dejans, A.', 'Van Hooreweder, B.', 'Vrancken, B.']

2024-03-26T20:51:52Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124407', 'https://doi.org/10.26153/tsw/51015']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['high speed video', 'beam shaping', 'overhang', 'laser powder bed fusion']

HIGH SPEED VIDEO IMAGING OF OVERHANG SURFACES IN BEAM SHAPED LASER POWDER BED FUSION OF 316L STAINLESS STEEL

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1e640f5f-4a59-4e27-b9aa-43845decc525/download

University of Texas at Austin

Beam shaping has seen rising interest in the AM industry and research field because of the increased level of control over the spatial distribution of the thermal input during Laser Powder Bed Fusion, allowing for faster build rates. This report investigates if the more uniform heat input offers benefits to the scanning of unsupported overhanging structures. In-situ high speed video imaging is combined with post process surface characterization to derive a relation between the scan parameters and quality of the overhang surface. The best results were achieved at low energy densities, but no clear advantage of top-hat shaped laser spots over the standard Gaussian beams is observed.

null

['Fish, S.', 'Kubiak, S.', 'Wroe, W.', 'Booth, J.', 'Bryant, A.', 'Beaman, J.']

2021-10-19T18:19:24Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89316

eng

2014 International Solid Freeform Fabrication Symposium

Open

['High Temperature Polymers', 'Selective Laser Sintering', 'testbed', 'process control']

A High Temperature Polymer Selective Laser Sintering Testbed for Controls Research

Conference paper

https://repositories.lib.utexas.edu//bitstreams/30c54b33-8f24-4001-8d44-eeb88353e36d/download

University of Texas at Austin

High Temperature Polymers under development over the last decade show great promise for Additive Manufacturing (AM) applications in aviation, medicine, and other fields based on their high strength and high temperature qualities. Selective Laser Sintering (SLS) of these materials, derived generally from the Poly Ether Ketone Ketone class of polymers is still somewhat immature however, and certifiably repeatable SLS parts with certifiable mechanical properties remain elusive. One barrier to this is the limited number and high cost of SLS machines capable of operating at the high ~300-350C temperatures needed to build with low internal thermal stress and tight process controls. Another barrier is the lack the instrumentation in the few machines available, to develop critical feedback control and associated flexibility in the thermal management of the material from feedstock to cooled part/part-cake. This paper describes the development and initial testing of a new laboratory SLS machine with the flexibility required in deriving optimal process control for polymer SLS including these high temperature polymer powders. With such a system validated for SLS operation, we will embark on multiple control development approaches to improve part/material property performance.

null

['España, Félix A.', 'Balla, Vamsi Krishna', 'Bose, Susmita', 'Bandyopadhyay, Amit']

2021-09-29T20:16:43Z

9/15/09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88211', 'http://dx.doi.org/10.26153/tsw/15152']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['surface modification', 'thermal conductivity', 'metal coating', 'Laser Engineered Net Shaping', 'LENS']

High Therma

Conference paper

https://repositories.lib.utexas.edu//bitstreams/fad5a991-77dd-4e8d-8972-3f4ade4a0814/download

University of Texas at Austin

Surface modification has been used to improve wear resistance, corrosion resistance and thermal barrier properties of metals. However, no significant attempts have been made to improve thermal conductivity by surface modification. In this work, we have examined the feasibility of enhancing thermal conductivity (TC) of stainless steel by depositing brass using Laser Engineered Net Shaping (LENS). The coating increased the TC of the substrate by 65% at 100 C°. Significantly low thermal contact resistance was observed between the coating and the substrate due to minimal dilution and defect free sound interface. Our results indicate that laser processing can be used on low coefficient of thermal expansion metal matrix composites to create feature based coatings to enhance their heat transfer capability.

null

High Thermal Conductivity Coatings via LENS™ for Thermal Management Applications

null

['Ledesma-Fernandez, J.', 'Tuck, C.', 'Hague, R.']

2021-10-19T17:43:53Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89307

eng

2014 International Solid Freeform Fabrication Symposium

Open

['high viscosity fluid', 'drop-on-demand', 'ink-jet printing', 'conductive pastes', 'dielectric pastes', 'printed electronics']

High Viscosity Jetting of Conductive and Dielectric Pastes for Printed Electronics

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9d04a680-db98-4fdf-86e9-4655f8346261/download

University of Texas at Austin

Ink-jet printing of multiple materials in 3 dimensions is a promising alternative to traditional patterning methods due to its flexibility, scalability and accuracy. However, the printability of the inks is strongly restricted by material properties such as surface tension and viscosity. Dispensing high viscosity fluids on a drop-on-demand approach is a potential solution that can facilitate the incorporation of new materials to the jetting catalogue. Consequently, in this study 2 micro-dispensing valves are used in combination with a mechanical stage to deposit conductive and dielectric pastes with viscosities of 15.3 ± 0.2 and 0.638 ± 0.005 Pa·s (at 25°C and 10 s-1 shear rate) respectively. Crucial printing parameters such as pressure, temperature, pulse shape and drop spacing are studied in order to optimise the process. Additionally, post-printing characteristics such as contact angle of different materials and cured layer profiles are also measured and taken into account during the designing of the 3D patterns to minimise the negative effects of the thickness miss-match of different materials. Finally, the manufacturing capability of the set-up is demonstrated by the fabrication of a functional device using a combination of “pick-and-place” components and high viscosity jetting.

null

['Yang, H.', 'He, Y.', 'Tuck, C.', 'Wildman, R.', 'Ashcroft, I.', 'Dickens, P.', 'Hague, R.']

2021-10-11T20:57:44Z

2013

Mechanical Engineering

null

['https://hdl.handle.net/2152/88642', 'http://dx.doi.org/10.26153/tsw/15576']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['3D inkjet printing', 'high viscosity ink', 'process parameters', 'temperature', 'pressure', 'jetting performance', 'jetting']

High Viscosity Jetting System for 3D Reactive Inkjet Printing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/50497175-7e2e-48db-84bc-a4eb3b10892c/download

University of Texas at Austin

High viscosity ink is a potential solution for the improvement of current 3D ink jetting technology. In this study, experiments are carried out to study a series of inks with differing viscosities jetted with PicoDot™ jet valves under different process parameters of temperature and pressure. Results show that a wide range of ink materials from low viscosity (water like materials) to very high viscosity (thixotropic materials) can be jetted with the piezoelectric actuated jet valves without the need of solvents and surfactants. The jetting volume can be controlled under certain conditions between 2nl and 15nl. The jetting performances for low, medium and high viscosity inks have been recorded by high-speed video photography.

null

['Fischer, S.', 'Pfister, A.', 'Galitz, V.', 'Lyons, B.', 'Robinson, C.', 'Rupel, K.', 'Booth, R.', 'Kubiak, S.']

2021-10-27T22:33:23Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89634

eng

2016 International Solid Freeform Fabrication Symposium

Open

['PEKK composites', 'carbon fiber', 'laser sintering', 'aerospace']

A High-Performance Material for Aerospace Applications: Development of Carbon Fiber Filled PEKK for Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ab093a90-e99a-4b83-903e-542e4cd58b63/download

University of Texas at Austin

In a time where rapid prototyping successively transforms to additive manufacturing (AM), nylon 11 and 12 and their composite powders, which have evolved to be the most commonly used materials in laser sintering (LS) due to their easy processability, cannot fulfil all challenging requirements of industrial applications any more. Especially in the aerospace industry, there is a high demand for stiff and lightweight parts for interiors, which currently are fabricated from glass fiber reinforced phenolic and epoxy resins by a lamination process. Due to the strong diversity of the parts, this traditional manufacturing is quite labor-intensive and expensive, which makes it very attractive to manufacture these parts with additive manufacturing, especially laser sintering. Additional part design requirements, such as greater chemical and UV resistance, an elevated softening temperature, higher mechanical strength and better performance in flammability and heat release tests generate opportunities for the use of high performance AM polymers. Promising candidates that have the potential of satisfying these demands can be found among the different Polyaryletherketone thermoplastics. In this work we present the development of a carbon fiber filled PEKK composite material for laser sintering, optimized especially for the production of interiors, such as air ducts for cabin ventilation in aerospace application. Based on process tests, powder characterization and test builds, the material and its manufacturing procedure were optimized towards isotropic properties and refreshability. Simulations of building cycles helped to understand the extent of powder ageing, which is directly connected to the ability to recycle the material. Furthermore the laser sintering hardware of an EOSINT P800 and the building processes were adapted to ensure a stable building process and fulfill the requirements of parts on mechanical properties in x, y and z directions, dimensional stability and surface quality.

null

['Elsab, A.', 'Wegner, Jan', 'Schonrath, Hanna', 'Horstjann, Niklas', 'Kleszczynski, S.']

2024-03-26T20:54:38Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124408', 'https://doi.org/10.26153/tsw/51016']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'PBF-LB/M', 'process monitoring', 'high resolution', 'balling effect']

HIGH-PRECISION MEASUREMENT OF MELT POOL PROPERTIES DURING LASER-BASED POWDER BED FUSION OF METALS BY HIGH-SPEED IMAGING

Conference paper

https://repositories.lib.utexas.edu//bitstreams/06d98b9c-0e4c-4de4-b982-0c9446926fe7/download

University of Texas at Austin

Laser-based powder bed fusion of metals is used to produce complex and high-performance components for different industrial applications. Due to the high complexity of the underlying physical mechanisms during the process, its control is still challenging. To avoid the formation of defects, which affect mechanical properties, a huge amount of specific know-how is crucial. Especially for regulated industries, such as medical or aerospace, this is a limiting factor for the widespread usage. In this work, high-speed imaging in combination with a high-magnification optic is used to gain deeper insight into the property-determining mechanisms and boundary conditions during the process. Thereby, the intensity distribution from the melt pool radiation is measured and analyzed with an imaging script to determine width, length, and cooling rate with a resolution of 1.44 µm/pixel. The potential of this data for predicting resulting scan track properties is demonstrated. It can be shown that an automatic width measurement deviates from the manually measured value by only 1.2% and the length measurement by 1.4%. It is also possible to detect anomalies in the process, such as balling effects.

null

['Sammons, Patrick M.', 'Barton, Kira']

2021-11-04T20:30:02Z

2017

Mechanical Engineering

null

['https://hdl.handle.net/2152/90021', 'http://dx.doi.org/10.26153/16942']

eng

2017 International Solid Freeform Fabrication Symposium

Open

['molten polycaprolactone', 'PCL', 'electrohydrodynamic jet printing', 'e-jet printing']

High-Resolution Electrohydrodynamic Jet Printing of Molten Polycaprolactone

Conference paper

https://repositories.lib.utexas.edu//bitstreams/124233b6-2335-438c-94de-acae6abf4bbd/download

University of Texas at Austin

Polycaprolactone (PCL) is a biocompatible and biodegradable polymer that is commonly used in drug delivery systems, medical structures, and tissue engineering applications. Typical additive manufacturing methods of PCL structures for tissue engineering applications either require harsh organic solvents or are only capable of producing relatively large feature sizes, which are not compatible with some of the desired applications. Electrohydrodynamic jet (e-jet) printing, an additive manufacturing process which uses an electric field to induce jetting from a microcapillary nozzle, is an attractive method for producing PCL tissue engineering structures due to the achievable resolution and the ability to print highly viscous inks. In this work, experimental investigation into the ability to print pure, molten PCL using the e-jet process is carried out. A characterization of the process inputs that yield suitable printing regimes is presented. Demonstration of the achievable resolution with e-jet printing is presented in the form of printed, high-resolution structures.

null

['Gillo, M.', 'Kruth, J.-P.', 'Vanherck, P.']

2019-10-09T16:02:39Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76146', 'http://dx.doi.org/10.26153/tsw/3235']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Recoating

High-Speed Curtain Recoating for Stereolithography

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ff52b2b8-de20-4bff-8a5d-047fa8f9c1cd/download

null

The University of Leuven uses a liquid curtain recoating system for resin deposition in stereolithography. This system deposits new liquid layers of photo-polymer by means of a liquid curtain travelling over the build vat. Experiments have been carried out to increase the speed of the liquid curtain while depositing a layer. Speeds up to 1.2 m/s, and accelerations up to 1 g have been tested successfully, meaning that it is possible to coat high-quality layers of 75 µm thickness with this recoating technique. However, the curtain restores too slowly after acceleration. This paper discusses possible reasons and tries to formulate adequate solutions. Possible solutions consist in controlling small pressure differences in the curtain’s neighbourhood. A solution to this problem is necessary, as to make the travelling length of the curtain, and so the machine length acceptable with respect to the dimensions of the build vat.

null

Levy, Richard A.

2018-10-03T15:31:42Z

1994

Mechanical Engineering

doi:10.15781/T2X05XX8G

http://hdl.handle.net/2152/68647

eng

1994 International Solid Freeform Fabrication Symposium

Open

['Medical imaging', 'Craniofacial CT Imaging', '3D Reconstruction']

Histogram - Based Algorithm for Semiautomated Three-Dimensional Craniofacial Modeling

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8eab29a8-5cc2-47b9-94b9-0770c6b597c5/download

null

Volume averaging artifacts in medical imaging result from voxel occupancy by more than one tissue type and, with anisotropic voxels, may be decreased by changing the imaging plane orientation relative to the target tissue and/or by decreasing slice thickness.1 In craniofacial CT imaging, volume averaging artifact becomes significant in areas ofthin bone such as the orbital walls and auditory ossicles. These regions are customarily imaged using multiple scan planes and the thinnest slices possible to reduce such artifacts. In three-dimensional craniofacial imaging, these same parameters may be controlled to reduce partial volume averaging, but areas of bone "drop-out" (also called pseudoforamina) are commonly present secondary to a paradoxical inability to lower thresholds without including unwanted background tissues. At present, the optimal solution to this problem is achieved by manually (and often painstakingly) drawing a region of interest around tissues presumed to contain volume averaged target density voxels and lowering thresholds to include these voxels in the 3D reconstruction, one CT slice at a time. Recently, anatomic modeling technologies have demonstrated the feasibility of assembling particulate hydroxyapatite (SYnthetic bone) into detailed craniofacial models of high anatomic accuracy, theoretically suitable for in vivo implantation (work in progress with the Department of Mechanical Engineering, University of Texas at Austin.) These modeling systems, such as stereolithography and selective laser sintering, operate as do 3D imaging workstations, using thresholds to 198 include/exclude pixels from CT data sets in the modeling process. However, the user interactive capabilities ofsuch technologies may be limited such that manual tracing ofregions of volume averaged thin bone is not possible. Drop-out artifacts in models so generated would be potentially larger than on corresponding 3D images where user input could reduce these artifacts. To circumvent this inability to manually correct volume averaging artifacts on anatomic modeling systems, and to relieve the intensive oPerator input required to otherwise achieve this goal on 3D imaging software, a histogram-based algorithm for semiautomated threedimensional craniofacial modeling was develoPed.

null

['Lorenz, Adam M.', 'Sachs, Emanuel M.', 'Allen, Samuel M.', 'Cima, Michael J.']

2019-10-09T16:10:22Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76149', 'http://dx.doi.org/10.26153/tsw/3238']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Infiltration

Homogeneous Metal Parts by Infiltration

Conference paper

https://repositories.lib.utexas.edu//bitstreams/300a7741-c6ff-4517-8021-9192e225ec34/download

null

Infiltration of powdered metal parts made by SFF processes enables densification with negligible dimensional change, but typically uses a dissimilar infiltrant material resulting in poor corrosion resistance, machinability, and a heterogeneous composition inconducive to certification for critical applications. A new approach called transient liquid-phase infiltration is described using an infiltrant composition similar to that of the powder skeleton, but containing a melting point depressant. Upon infiltration, the liquid undergoes diffusional solidification at infiltration temperature and eventually the composition becomes homogeneous. Parts over 20 cm tall have been fabricated through careful selection of skeleton and infiltrant compositions, skeleton powder size, and infiltration technique. The work presented in this paper uses a nickelsilicon alloy to infiltrate a skeleton of pure nickel powder.

This research was sponsored by the Office of Naval Research, Contract #N00014-99-1-1090.

null