ccm/sff-papers · Datasets at Hugging Face

['Nelson, Christian', 'Kepler, Jason', 'Booth, Rick', 'Conner, Phillip']

2019-02-26T16:33:34Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73483', 'http://dx.doi.org/10.26153/tsw/633']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['Rapid Tooling', 'DTM']

Direct Injection Molding Tooling Inserts from the SLS Process with Copper Polyamide

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a25c9595-6d2f-4f27-b0a2-a49e033735ab/download

null

The "RapidTool" Short Run (SR) Tooling Process using the Copper Polyamide material provides a route to mold inserts for injection molding made directly in the Selective Laser Sintering machine. The STL files for the mold inserts are shelled and conformal cooling lines and ejector pin guides are added before SLS processing. Sintering of the material in the SLS machine provides quick metal/plastic tooling with good thermal conductivity. Final preparation of the tooling inserts includes sealing the surface with epoxy, final finishing using sandpaper, and backing up the shells with a metal alloy. The Copper Polyamide SR Tooling inserts are used to mold several hundred parts with common plastics with injection cycle times similar to conventional molding cycle times.

null

['Yan, Lei', 'Chen, Xueyang', 'Li, Wei', 'Liou, Frank', 'Newkirk, Joe']

2021-10-20T21:48:16Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89370

eng

2015 International Solid Freeform Fabrication Symposium

Open

['direct laser deposition', 'powder blends', 'microstructure', 'composition distribution']

Direct Laser Deposition of Ti-6Al-4V from Elemental Powder Blends

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2558bedc-301b-4dfb-b385-e941075efb13/download

University of Texas at Austin

A thin-wall structure composed of Ti-6Al-4V has been deposited using direct laser deposition (DLD) from blended Ti, Al, and V elemental powders. The microstructure and composition distribution along the build height direction were intensively investigated using optical microscopy, scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS), and Vickers hardness testing. The microstructures of the as-deposited Ti-Al-V were studied using EDS to determine appropriate weight percentage for Al and V in the blended powders before mixing. The effects of laser power and laser transverse speed on the microstructure were investigated and optimized laser processing parameters were concluded.

null

['Das, Suman', 'P. Fuesting, Timothy', 'Danyo, Gregory', 'Brown, Lawrence E.', 'Beaman, Joseph J.', 'Bourell, David L.', 'Sargent, Kathleen']

2019-02-18T17:30:09Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73391', 'http://dx.doi.org/10.26153/tsw/543']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['affordability', 'technique']

Direct Laser Fabrication of a Gas Turbine Engine Component - Microstructure and Properties - Part I

Conference paper

https://repositories.lib.utexas.edu//bitstreams/af208a6d-65c9-4b51-b019-da5158482253/download

null

This paper presents the development of a new technique for the production of abrasive turbine blade tips by direct laser processing. This superalloy cermet component is an integral part of the low pressure turbine sealing system in a demonstrator engine. Direct laser fabrication of this component fiom a bed a loose powder results in significant cost savings and improved performance over the currently employed production technique. The technology has been demonstrated by fabricating a prototype lot of 100 blade tips, which will be subjected to an engine test. This is the first instance of a direct fabrication method applied to the production of functional engine hardware. This research was funded by the United States Air Force contract F33615-94- C-2424 titled "Affordable Turbine Blade Tips".

null

['Wohlert, Martin', 'Das, Suman', 'Beaman, Joseph J.', 'Bourell, David L.']

2019-03-12T19:58:24Z

1999

Mechanical Engineering

null

['https://hdl.handle.net/2152/73607', 'http://dx.doi.org/10.26153/tsw/749']

eng

1999 International Solid Freeform Fabrication Symposium

Open

['SLS', 'Alloy 625']

Direct Laser Fabrication of High Performance Metal Components Via SLS/HIP

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ba0202c1-c105-46ee-bfcf-eab883186930/download

null

Recent research in the area of direct freeform fabrication of components via selective laser sintering/hot isostatic pressing (SLS/HIP) has focused on the processing of Alloy 625. Alloy 625 is a nickel-based superalloy which provides high temperature strength and corrosion resistance. Alloy 625 test specimens were successfully SLS processed with an integral gas impenneable skin or "can". These samples were subsequently HIPed to high density (>99.5%). Characterization of the test specimens indicated that microstructures similar to conventionally processed P/M materials are achieved in the HIP consolidated "core" region ofthe parts, while structures similar to those found in cast materials are present in the SLS processed "can" regions. Mechanical analysis of Alloy 625 SLS/HIP parts and production of complex structures will commence shortly.

null

['Klocke, F.', 'McClung, A.', 'Ader, C.']

2020-02-13T19:08:25Z

8/4/04

Mechanical Engineering

null

['https://hdl.handle.net/2152/79961', 'http://dx.doi.org/10.26153/tsw/6986']

eng

2004 International Solid Freeform Fabrication Symposium

Open

Selective Laser Sintering

Direct Laser Sintering of Borosilicate Glass

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3234094a-3774-46b1-b8ef-f34b54ae6b2a/download

null

Despite the advantages that selective laser sintering (SLS) offers in terms of material availability, many materials have yet to be explored for feasibility and even fewer are available on a commercial basis. This paper presents initial investigations for one such material, borosilicate glass, which could be of particular interest to filter manufacturers because it presents an attractive alternative to the conventional, time-consuming way of producing filters of various porosity classes. Process results are presented including a determination of the optimal parameter window and the effect of processing parameters on the density and surface quality. The effects of thermal post-processing and the inclusion of an additive are also discussed.

null

['Klocke, F.', 'Ader, Christoph']

2019-11-21T18:02:10Z

2003

Mechanical Engineering

null

['https://hdl.handle.net/2152/78549', 'http://dx.doi.org/10.26153/tsw/5605']

eng

2003 International Solid Freeform Fabrication Symposium

Open

Ceramics

Direct Laser Sintering of Ceramics

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a52bcc83-70d9-4824-ac7c-4e30f08b80bd/download

null

For more than one decade layer manufacturing technologies assist the development of new products. Due to a layer-wise build-up of a three-dimensional geometry, nearly every complex design is producible in a short period of time. Selective Laser Sintering is a powderbased technique to produce plastic prototypes (Rapid Prototyping) or metal mould inserts (Rapid Tooling). The laser sintering of ceramic powder is not yet commercialized but applications could be both Rapid Prototyping and Rapid Tooling. The former involves the laser sintering of investment casting shells and cores to cast metal prototypes and the latter the laser sintering of ceramic master patterns for metal spray forming of steel mould inserts. The advantage compared to actual processes are a faster availability of the final product. To facilitate these applications, special ceramic powders as well as new process parameter combinations were investigated. This paper will present achieved results within the abovedescribed applications.

null

['Carter, William T.', 'Jones, Marshall G.']

2018-05-03T16:44:29Z

1993

Mechanical Engineering

doi:10.15781/T2513VD0T

http://hdl.handle.net/2152/65036

eng

1993 International Solid Freeform Fabrication Symposium

Open

['CAD', 'laser beam', 'rapid prototyping', 'stereolithography']

Direct Laser Sintering of Metals

Conference paper

https://repositories.lib.utexas.edu//bitstreams/dea2ff2e-bf4f-4ee5-acc1-f5ea3905b4d2/download

null

The use of a directed laser bealn source to selectively sinter multiple layers of binderless metal powder for the purposes of rapid prototyping is described. The work in this paper is restricted to -325 mesh iron powder, which was sintered using a C\V 50 W Nd:YAG laser to approximately 3.5% density. A subsequent post-treatlnent was perfornled to achieve a fully dense saulple. It is envisioned that such a system can be used to manufacture functional metallic prototypes directly from CAD without part-specific tooling.

null

['Wilkening, C.', 'Sindel, M.', 'Pintat, T.', 'Greul, M.', 'Nyrhila, O.']

2018-09-26T20:36:38Z

1994

Mechanical Engineering

doi:10.15781/T28P5VV59

http://hdl.handle.net/2152/68595

eng

1994 International Solid Freeform Fabrication Symposium

Open

['direct laser sintering', 'rapid prototyping', 'selective-laser sintering']

Direct Laser Sintering of Metals and Metal Melt Infiltration for Near Net Shape Fabrication of Components

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e3421af5-4ba4-4997-a205-7bfbca3bbafb/download

null

Direct laser sintering of metal powders is a great challenge for Rapid Prototyping (RP) because of the high potential of application, for example prototype tooling for polymer extrusion. Recent development in laser sintering ofmetal powders use polymer or low melting alloys as a binder phase. Postsintering to strengthen the component produces shrinkage ofthe part, hence the near net shape capability is limited. The combination of direct laser sintering and infiltration with metal melts allows the production ofstrong near net shaped components without shrinkage. A composite metal powder consisting ofNi, Cu, Sn and P was successfully sintered in a Selective-Laser Sintering unit in ambient atmosphere at room temperature. The influence oflaser intensity on microstructure and sintering behaviour is discussed. Infiltration experiments were done with partially sintered samples. Full density could be achieved without shrinkage. Mechanical properties and microstructural development will be discussed.

null

['Klocke, Fritz', 'Wirtz, H', 'Meiners, W.']

2018-11-09T16:29:29Z

1996

Mechanical Engineering

doi:10.15781/T2XS5K282

http://hdl.handle.net/2152/69931

eng

1996 International Solid Freeform Fabrication Symposium

Open

['selective laser sintering', 'polymer binder', 'metal build up']

Direct Manufacturing of Metal Prototypes and Prototype Tools

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e8ab4a32-dbdc-4e20-ba1b-b5be5ba96a1d/download

null

Due to the limited mechanical characteristics of the materials which can currently be processed using industrially available Rapid Prototyping machines, a lot of research is focused on the development of techniques which allow a direct manufacturing of metallic parts. These include Selective Laser Sintering and Controlled Metal Build Up. Both methods produce the workpiece not by removal of material but by a layerwise deposition and local melting or sintering of a powder material without part-specific tooling. Controlled Metal Build Up is a new Rapid Prototyping technique similar to Fused Deposition Modeling combining laser generating/welding with conventional 2Y2 dimensional milling. Due to the excellent surface quality and high dimensional and form accuracy achievable with Controlled Metal Build Up, this technology offers an interesting alternative to the conventional time consuming processes for the manufacture of prototype tools required for limited production runs. With respect to Selective Laser Sintering, a test facility was developed for experimental investigations into the direct sintering of low and high melting metallic powders without the use of a polymer binder as well as ceramic powders. Great potential is expected from Selective Laser Sintering concerning the prototyping of molds and dies. This paper will discuss current developments for these two techniques as well as point out possible applications and future developments.

null

['Ramos-Grez, Jorge', 'Sanz-Guerrero, Jorge', 'Larraín, Tomás', 'Ramírez, Andrés']

2020-02-28T15:58:54Z

2006

Mechanical Engineering

null

['https://hdl.handle.net/2152/80113', 'http://dx.doi.org/10.26153/tsw/7134']

eng

2006 International Solid Freeform Fabrication Symposium

Open

Direct Metal Laser Fabrication

Direct Metal Laser Fabrication of Cu Slabs from Powder Precursor: Surface Depth of Melt and Furnace Temperature Issues

Conference paper

https://repositories.lib.utexas.edu//bitstreams/036e1e0a-e03f-4a3e-81f6-b09be34de1a0/download

null

A DMLF processing unit based on a raster-scanned 80 W CO2 laser beam has been developed to process single layers of metallic powder precursor. The process chamber provides atmosphere control (high vacuum and inert gas refill) besides temperature elevation up to 700 o C. In this work, copper powder precursor is confined inside a refractory steel mask surrounded by an aluminum oxide jacket that acts as insulator. The powder layers can have thicknesses of 0,5 and 1 mm. An infrared pyrometer measures in real time the temperature at one location in the surface of the powder bed. Scan speed, scan step, and furnace temperature have been varied to find combinations of such parameters that render surface melting and maximum densification. Partially melted samples were produced and their mass density was measured. Micro-hardness and surface roughness were also measured along the resolidified surface, the first rendering an average of 80,6 HV compared to the 90-105 HV of oxygen free copper, while the second resulting in an 8 μm Ra value. Maximum melt of depth achieved is ~0,15 mm followed by a sintered layer.

null

['Carter, William T.', 'Graham, Michael E.', 'Hayden, Christopher', 'Jeong, Younkoo', 'Mamrak, Justin', 'McCarthy, Brian', 'Monaghan, William', 'Nieters, Edward J.', 'Ostroverkhov, Victor', 'Roychowdhhury, Subhrajit', 'Schmitz, Andrea', 'Tucker, Michael R.']

2021-11-18T19:00:16Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90468', 'http://dx.doi.org/10.26153/tsw/17389']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['direct metal laser melting', 'DMLM', 'rotating powder bed', 'aircraft engine industry']

A Direct Metal Laser Melting System Using a Continuously Rotating Powder Bed

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ad054fe6-253a-4dbc-bff1-5aec61cd6001/download

University of Texas at Austin

The aircraft engine industry manufactures many metal parts of large diameter, but small cross-sectional area. Designers of these parts require increasingly complex geometries for improved aerodynamic efficiency and cooling. The combination of large diameter and complex geometric features inspired the development of a new Direct Metal Laser Melting (DMLM) architecture with a rotating powder bed. The system coordinates the rotational motion of a powder bed with an ascending laser scanner and recoater to build in a helical fashion. A single-point powder feeder delivers metal powder near the inner radius of an annular build volume, and the recoater spreads the powder to the outer radius in a “snow plow” fashion. Because the recoater and laser scanner are installed at different angular positions, they operate independently and simultaneously. A prototype system was built to demonstrate this concept for an aircraft engine combustor liner (600-mm dia. x 150-mm ht.) and showed continuous laser utilization exceeding 97%.

null

['Morgan, Rhys', 'Papworth, Adam', 'Sutcliffe, Chris', 'Fox, Pete', "O'Neill, Bill"]

2019-10-18T15:03:36Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76231', 'http://dx.doi.org/10.26153/tsw/3320']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Primitives

Direct Metal Laser Re-Melting of 316L Stainless Steel Powder Part 2: Analysis of Cubic Primitives

Conference paper

https://repositories.lib.utexas.edu//bitstreams/47a416a6-d771-4510-8618-6894e204234f/download

null

Direct Metal Laser Re-Melting is a process variant of Selective Laser Sintering, whereby 316L stainless steel powder fractions are melted by a high power Nd:YAG laser. Layers are built up as a series of single lines to produce thin walled structures in the range »0.3-1.0mm thick. The structures exhibit a periodic, angular roughness to the wall surfaces. The samples also display a wave-like pattern on their upper surfaces. Further investigations reveal the angled ‘wave’ pattern exists on a macroscopic level in the microstructure. The pattern is fully formed by the third or fourth layer. Fern-like grain structures follow the orientation of the surface roughness and exist across many layers. This is believed to be the effect of grain orientation within the samples. The microstructure reveals long, needle, cell structures. The uni-axial needles grow epitaxially from previous layers. The samples have been shown to exhibit very little or no thermally induced residual stresses. Introduction

null

['Das, Suman', 'Wohlert, Martin', 'Beaman, Joseph J.', 'Bourell, David L.']

2018-11-28T19:45:04Z

1997

Mechanical Engineering

doi:10.15781/T2PZ52629

http://hdl.handle.net/2152/70328

eng

1997 International Solid Freeform Fabrication Symposium

Open

['CAD', 'SLS']

Direct Selective Laser Sintering and Containerless Hot Isostatic Pressing for High Performance Metal Components

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4ea0d668-9945-4e4c-bb4b-ce385409e227/download

null

A novel net shape manufacturing method known as SLSIHIP that combines the strengths ofselective laser sintering (SLS) and hot isostatic pressing (HIP) is presented. Direct selective laser sintering is a rapid manufacturing technique that can produce high density metal components of complex geometry with an integral, gas impermeable skin. These components can then be directly post-processed to full density by containerless HIP. The advantages of in-situ HIP encapsulation include elimination of a secondary container material and associated container-powder interaction, reduced pre-processing time, a short HIP cycle and reduction in post-processing steps compared to HIP of canned parts. Results of research conducted on Inconel 625 superalloy, Ti-6AI-4V and Monel are presented. This research is funded by DARPAlONR contract N00014-95-C0139 titled "Low Cost Metal Processing Using SLSIHIP".

null

['Zong, G.', 'Wu, Y.', 'Tran, N.', 'Lee, I.', 'Bourell, D.L.', 'Beaman, J.J.', 'Marcus, H.L.']

2018-04-19T16:15:36Z

1992

Mechanical Engineering

doi:10.15781/T2V980830

http://hdl.handle.net/2152/64379

eng

1992 International Solid Freeform Fabrication Symposium

Open

['Center for Materials Science and Engineering', 'Department of Mechanical Engineering', 'SLS']

Direct Selective Laser Sintering of High Temperature Materials

Conference paper

https://repositories.lib.utexas.edu//bitstreams/161858a9-ba25-4bd3-af3b-43224a390ef0/download

null

Selective Laser Sintering (SLS) involving a coexisting liquid and particulate solid during the SLS processing can be used to produce freeform parts directly with high temperature materials. Factors such as scanning laser power density, residence time, scan line spacing, the interfacial energies between the liquid and solid phases, powder bed biasing temperature, and sintering atmosphere greatly affect the microstructure evolution in the SLS process. Direct SLS of high melting temperature mixed powder materials was demonstrated using a 1.1 kW C02 laser SLS system. The relationship between the microstructures and the process parameters will be described.

null

['Meyers, Sebastian', 'Kruth, Jean-Pierre', 'Vleugels, Jef']

2021-10-21T22:00:17Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89454

eng

2015 International Solid Freeform Fabrication Symposium

Open

['direct selective laser sintering', 'reaction bonded silicon carbide', 'silicon carbide']

Direct Selective Laser Sintering of Reaction Bonded Silicon Carbide

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6267a2a0-b6c3-4128-912a-db5f182f5afa/download

University of Texas at Austin

Three-dimensional reaction bonded silicon carbide (SiSiC or RBSC) parts have been produced by direct selective laser sintering (SLS). Unlike previously investigated processing routes, which make use of a sacrificial polymer binder to form green parts, the parts in this work are built by scanning subsequent layers composed of a mixture of silicon and silicon carbide powders. A fibre laser is used to selectively melt the silicon under an inert argon atmosphere, resulting in porous preforms of sufficient strength for further handling and processing. After impregnation with a graphite suspension and infiltration with liquid Si at 1450°C, highly dense reaction bonded silicon carbide parts are obtained.

null

['Klocke, Fritz', 'Wagner, Christian']

2019-10-23T14:33:31Z

2002

Mechanical Engineering

null

['https://hdl.handle.net/2152/76703', 'http://dx.doi.org/10.26153/tsw/3792']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Superalloys

Direct Selective Laser Sintering of Superalloys

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d0f44ab7-c36b-4e15-a38d-53c46847611a/download

null

The advantages of powder metallurgy lie within the large degree of freedom for material design and thus is especially used in the production of high performance parts. Layer manufacturing is an appropriate method to produce complex parts rapidly. Direct Selective Laser Sintering (SLS) presents a technology which combines both benefits. Therefore many efforts are done today to qualify new materials for SLS [DAS 98, MEI 99, OVE 01, WOL 00]. Particulary materials, which are hard to cut, to cast or to shape in any else matter, are of interest. In the presented paper investigation results on Selective Laser Sintering of metals are shown on the basis of the nickel base alloy INCONEL™ 718. First, a process model has been created to discribe the mechanisms of SLS of metals. On the base of the model, process simulations and experimental investigations have been performed. In some cases, affiliating a heat treatment after the laser sintering step is favorably to improve the metallic structure and thus has also been tested. Finally, the metallograhic structures and mechanical properties were analysed.

null

['Hauser, C.', 'Childs, T.H.C.', 'Taylor, C.M.', 'Badrossamay, M.', 'Akhtar, S.', 'Wright, C.S.', 'Youseffi, M.', 'Kie, J.', 'Fox, P.', 'O’Neill, W.']

2019-11-21T18:48:45Z

2003

Mechanical Engineering

null

['https://hdl.handle.net/2152/78569', 'http://dx.doi.org/10.26153/tsw/5625']

eng

2003 International Solid Freeform Fabrication Symposium

Open

Direct Selective

Direct Selective Laser Sintering of Tool Steel Powders to High Density: Part A - Effects of Laser Beam Width and Scan Strategy

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ebb60ec0-1457-4c16-b383-a0bddabd801a/download

null

This paper describes progress on the Direct Selective Laser Sintering of M2 and H13 tool steel powders, comparing this with previous and further observations on stainless steel powders. The distinguishing feature is the melting of single tracks and layers in deep powder beds. The paper focuses on changing characteristics of the melt pool (mass, volume, aspect ratio, stability) and laser-powder interactivity as the laser beam width, power and scan speed change. It also compares the melt pool of neighbouring tracks during single layer construction. Simulations from a computer model to predict melt pool shape and dimension show reasonable agreement with experimental results at low scan speeds (0.5mm/s). But unexpected increases in melt depth above 1.0mm/s have been observed, suggesting higher values and more variability in laser absorptivity than expected, even approaching 1.0 for the CO2 laser radiation used in this work.

null

['Akhtar, S.', 'Wright, C.S.', 'Youseffi, M.', 'Hauser, C.', 'Childs, T.H.C.', 'Taylor, C.M.', 'Baddrossamay, M.', 'Xie, J.', 'Fox, P.', 'O’Neill, W.']

2019-11-21T18:51:29Z

2003

Mechanical Engineering

null

['https://hdl.handle.net/2152/78570', 'http://dx.doi.org/10.26153/tsw/5626']

eng

2003 International Solid Freeform Fabrication Symposium

Open

Direct Selective

Direct Selective Laser Sintering of Tool Steel Powders to High Density: Part B -The Effect on Microstructural Evolution

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3e8ae3f3-cee5-45f1-ab8a-cc77f1ba5d88/download

null

This paper describes recent progress on the Direct Selective Laser Sintering of M2 [Fe6W-5Mo-4Cr-2V-0.8C] high speed steel (HSS) and H13 [Fe-5Cr-1V-1Si-1.5Mo-0.4C] tool steel powders. Part B will focus on the microstructural evolution of laser scanned powder beds. It has been found that H13 powders are more amenable to Direct Selective Laser Sintering than M2 powders. Densities up to 90% are possible with H13 powder compared with 70% for M2. The relationship between alloy composition, microstructure, post-scanned density and scan conditions will be discussed for single track, single layer and multi-layer constructions.

The research reported in this paper is a joint project between the Universities of Bradford, Leeds and Liverpool, funded by the UK Engineering and Physical Sciences Research Council under Grant Number GR/R32222.

null

['Dhar, Joni', 'Lopez, Lazaro', 'Zhang, Shanshan', 'Xu, Ben', 'Uddin, Jasim', 'Li, Jianzhi']

2021-12-06T22:29:59Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90699', 'http://dx.doi.org/10.26153/tsw/17618']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', 'high entropy alloy', 'microstructure', 'additive manufacturing']

Direct Selective Laser Synthesis of CuCrFeNiTiAl High Entropy Alloy from Elemental Powders through Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5fb39ec0-8e43-442a-8cfe-ceb77e4adbee/download

University of Texas at Austin

This study investigated the synthesis of CuCrFeNiTiAl high entropy alloy (HEA) from pure elements using selective laser melting (SLM). The objectives are to validate the feasibility of the HEA fabrication from elemental powder materials, and to examine the effect of various process conditions in SLM, such as laser power, point distance and laser exposure time, on the microstructures formed. The as-built samples under high, medium and low energy densities were characterized by X-ray diffraction (XRD), and the microstructures were observed using scanning electron microscopy (SEM). The XRD results showed that five major crystal structure phases (hexagonal, monoclinic, orthorhombic, body-centered cubic and rhombohedral) were present in all samples. Fine-grained phases were noticed on the sample surface with non-uniform microstructural distribution. Such phases in high and low energy density samples were observed polygonal while round-shaped microstructures were observed for samples prepared under medium energy density conditions. Also, the grain size was proportional to energy levels of the fabrication process. Large size and clustered structures are prominent in samples produced under high energy density.

null

['Starly, B.', 'Lau, A.', 'Sun, W.', 'Lau, W.', 'Bradbury, T.', 'Youssef, A.', 'Gaylo, C.']

2019-11-20T16:06:00Z

2003

Mechanical Engineering

null

['https://hdl.handle.net/2152/78464', 'http://dx.doi.org/10.26153/tsw/5549']

eng

2003 International Solid Freeform Fabrication Symposium

Open

Direct Slicing

Direct Slicing of STEP Based NURBS Models for Solid Freeform Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5ffb9cdb-8839-4644-a84d-f7b90bc6bbd9/download

null

Direct slicing of CAD models to generate process planning instructions for solid freeform fabrication may overcome inherent disadvantages of using STL format in terms of the process accuracy, ease of file management, and incorporation of multiple materials. This paper will present the results of our development of a direct slicing algorithm for layered freeform fabrication. The direct slicing algorithm was based on a neutral, international standard (ISO 10303) STEP-formatted NURBS geometric representation and is intended to be independent of any commercial CAD software. The following aspects of the development effort will be presented: 1) Determination of optimal build direction based upon STEP-based NURBS models; 2) Adaptive subdivision of NURBS data for geometric refinement; and 3) Ray-casting slice generation into sets of raster patterns. Feasibility studies applying the direct slicing algorithm to example models and the generation of fabrication planning instructions involving multi-material structures will also be presented.

null

['Shishkovsky, IV.', 'Makarenko, A.G.', 'Petrov, A.L']

2018-11-28T20:51:26Z

1997

Mechanical Engineering

doi:10.15781/T2K64BC7C

http://hdl.handle.net/2152/70329

eng

1997 International Solid Freeform Fabrication Symposium

Open

['direct SLS', 'eutectic powder compositions', 'control exothermic reaction of combustion.']

Direct SLS of powder compositions used for self-propagating high-temperature synthesis

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e5d32d38-6eff-47be-a68d-2de4fbb97466/download

null

The conditions of a direct selective laser sintering (SLS) were resea;rched experimental in a volume and by layers for the eutectic and near-eutectic powder compositions, which usually used for the self-propagating high-temperature synthesis (SHS) technology. It was shown a possibility to realise during SLS process a control exothermic reaction of combustion exactly in the focus ofew-Iaser beam on Nd-YAG. The necessary parameters of a laser influence (a power, scan velocity and diameter'of the laser beam), a dispersion and composition of the powder mixtures were determined for the such regime. The 3D parts from intermetallic compounds were created without any post-process procedures, that expands the functional opportunities ofthe sintering models.

null

['Sparks, Todd', 'Liou, Frank']

2020-03-11T15:33:06Z

9/10/08

Mechanical Engineering

null

['https://hdl.handle.net/2152/80253', 'http://dx.doi.org/10.26153/tsw/7272']

eng

2008 International Solid Freeform Fabrication Symposium

Open

Laser Metal Deposition

Direct-to-Part Machining Waste Recycling using Laser Metal Deposition

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e542d4a0-3355-48e1-bb20-8d6c49d13546/download

null

['Dimos, D.', 'Yang, P.', 'Garino, TJ.', 'Raymond, M.V.', 'Rodriguez, M.A.']

2018-11-28T17:35:57Z

1997

Mechanical Engineering

doi:10.15781/T2BN9XP08

http://hdl.handle.net/2152/70323

eng

1997 International Solid Freeform Fabrication Symposium

Open

['High reliability', '3-D architectures', 'fabrication processes']

Direct-Write Fabrication of Integrated, Multilayer Ceramic Components

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ecb0271b-85e7-406e-880c-3cdb88279b16/download

null

The need for advanced (electronic) ceramic components with smaller size, greater functionality, and enhanced reliability requires the ability to integrate electronic ceramics in complex 3-D architectures. For rapid prototyping and small-lot manufacturing, traditional tape casting and screen printing approaches are poorly suited. To address this need, we are developing a direct-write approach for fabricating highly integrated, multilayer components using a micropen to deposit slurries in precise patterns. With this technique, components can be constructed layer by layer, simplifying fabrication. It can also be used to produce structures combining several materials in a single layer. The parts are either cofired or sequentially fired, after each layer is deposited. Since differential shrinkage can lead to defects in these multilayer structures, we are characterizing the sintering behavior ofindividua1layers. This technique has been used to fabricate devices such integrated RC filters, multilayer voltage transformers, and other passive components. The direct-write approach provides the ability to fabricate multifunctional, multimaterial integrated ceramic components (MMICCs) in an agile and rapid way.

null

['Yang, M.', 'Parvez, M.M.', 'Sparks, T.', 'Babalola, S.', 'Newkirk, J.W.', 'Chandrashekhara, K.', 'Bartlett, L.N.', 'Liou, F.']

2023-03-29T16:51:00Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117686', 'http://dx.doi.org/10.26153/tsw/44565']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Directed Energy Deposition (DED)', 'AF9628 Low Alloy Steel', 'Laser Power', 'Scan speed', 'Cooling Rate', 'Micro-tensile Test (YS, UTS, Elongation)']

Directed Energy Deposition Processing-Performance Relationship of AF9628

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a7477535-3546-4dc6-83dc-a0cfdcee55b7/download

null

AF9628 low alloy steel is a novel steel known for its low cost, high hardness, and outstanding tensile performance. However, the processing methods of AF9628 have been less studied in the additive manufacturing field. As the balance of hardness and tensile results is closely related to the cooling process during manufacturing process window and its relationship to resultant tensile properties was explored. By using the DED method, specimens of this steel were successfully fabricated, and tensile test results were obtained. The AF9628 steel can be manufactured for tailored properties with the DED process by controlling the cooling method. This work was funded by ARL - GVSC under cooperative agreement W911NF-20-2-0251.

null

['Imediegwu, Chikwesiri', 'Shaffer, Milo', 'Ryan, Mary', 'Panesar, Ajit']

2024-03-27T03:50:32Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124476', 'https://doi.org/10.26153/tsw/51084']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['topology optimisation', 'nanoarchitecture', 'battery']

Discovery of next-generation battery electrodes using topology optimisation

Conference paper

https://repositories.lib.utexas.edu//bitstreams/42edfa21-f380-4dd1-9bda-49d1b35d747e/download

University of Texas at Austin

Energy storage systems (ESSs) are essential components for the delivery of uninterrupted renewable energy of the future. A key stride towards the development of these systems revolves around the design of insertion-electrode batteries (IEBs). However, battery cell performance metrics of capacity and rate capability in these batteries are limited by inefficient ion and electron transport due to the complex transport channels the ions must navigate to reach storage sites – a fundamental limitation of slurry-cast (SC) type electrodes. We present a gradient-driven approach to derive optimal electrode architecture, constrained only by the underlying multiphysics system defining transport mechanisms in and across solid and liquid phases. The derived framework challenges the traditional manufacturing techniques for electrodes, inspiring novel strategies for deriving new high-performance electrodes.

null

['Menezes, C.', 'Turner, C.']

2021-12-07T17:27:07Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90730', 'http://dx.doi.org/10.26153/tsw/17649']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['discrete element modeling', 'printing parameters', 'fused deposition modeling']

Discrete Element Modeling of Fused Deposition Modeling Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/32e32f16-36da-484a-a3c3-d85a08ff14bb/download

University of Texas at Austin

Fused Deposition Modeling components show anisotropic material properties as a result of the difference in bonding strengths between inter- and intra-layer particles. This difference occurs due to temperature gradient of the deposited filaments which affects the filament adhesion as well as due to the presence of voids or other discontinuities in the printed object. Discrete Element Modelling (DEM) is a discontinuous methodology which follows the idea of treating filaments as discrete rigid particles with simplified geometries for calculating the thermal interactions between the particles. Models using this approach allow the investigators to correlate the adhesion effects between filaments based on experimental data which ultimately will allow for optimization of the relevant printing parameters.

null

['Jackson, Brad', 'Wood, Kris', 'Beaman, Joseph J.']

2019-09-23T15:28:05Z

2000

Mechanical Engineering

null

['https://hdl.handle.net/2152/75936', 'http://dx.doi.org/10.26153/tsw/3035']

eng

2000 International Solid Freeform Fabrication Symposium

Open

Arrays

Discrete Multi-Material Selective Laser Sintering (M2 SLS): Development for an Application in Complex Sand Casting Core Arrays

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f266dfd7-b8f6-49c1-b4c6-16650801a8bc/download

null

Conventional sand casting processes often take many weeks or months to produce the tooling required for a casting, in particular the fabrication of sand core arrays for hollow features in a casting. SLS is already being applied to produce complex sand core geometries and reduce production times, but a new development of discretely laying down two different materials and removing one after sintering will allow even more complex geometries and drastically decrease the production times of sand cores. Two of the most significant problems in the current use of SLS for sand cores are the mechanical removal of unsintered powder and damage during part breakout. The second discrete material serves as a support medium through the build and fabrication of the sand core and is removed before casting; the sacrificial second material increases green strength and eliminates time consuming post-processing. The development and plan for implementation of the discrete M2 SLS process is presented.

null

['Pal, D.', 'Stucker, B.E.']

2021-09-30T19:07:13Z

9/23/10

Mechanical Engineering

null

['https://hdl.handle.net/2152/88282', 'http://dx.doi.org/10.26153/tsw/15223']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['dislocation density based model', 'crystal plasticity quasi-static finite element', 'Ultrasonic Consolidation', 'dislocation density']

Dislocation Density Based Finite Element Modeling of Ultrasonic Consolidation

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e4fa1532-9f10-4279-8c93-94c2a0ffa28e/download

University of Texas at Austin

A dislocation density based constitutive model has been developed and implemented into a crystal plasticity quasi‐static finite element framework. This approach captures the statistical evolution of dislocation structures and grain fragmentation at the bonding interface when sufficient boundary conditions pertaining to the Ultrasonic Consolidation process are prescribed. Hardening is incorporated using statistically stored and geometrically necessary dislocation densities (SSDs and GNDs), which are dislocation analogs of isotropic and kinematic hardening respectively. The GND considers strain‐gradient and thus renders the model size‐dependent. The model is calibrated using experimental data from published refereed literature and then validated for the Aluminum 3003 alloy.

null

['Pal, D.', 'Stucker, B.E.']

2021-10-04T21:58:33Z

8/17/11

Mechanical Engineering

null

['https://hdl.handle.net/2152/88363', 'http://dx.doi.org/10.26153/tsw/15302']

eng

2011 International Solid Freeform Fabrication Symposium

Open

['dislocation density', 'crystal plasticity based finite element modeling', 'Ultrasonic Consolidation']

Dislocation Density Crystal Plasticity Based Finite Element Modeling of Ultrasonic Consolidation

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6f4a528b-fdf9-4bff-ab29-4eef12651030/download

University of Texas at Austin

A dislocation density based constitutive model has been developed and implemented into a crystal plasticity quasi-static finite element framework. This approach captures the statistical evolution of dislocation structures and grain fragmentation at the bonding interface when sufficient and necessary boundary conditions pertaining to the Ultrasonic Consolidation (UC) process are prescribed. The hardening is incorporated using statistically stored and geometrically necessary dislocation densities (SSDs and GNDs) which are dislocation analogs of isotropic and kinematic hardening respectively. Since, the macroscopic boundary conditions during UC involves cyclic sinusoidal simple shear loading along with constant normal pressure, the cross slip mechanism has been included in the evolution equation for SSDs. The inclusion of cross slip promotes slip irreversibility, dislocation storage and, hence, cyclic hardening during the UC. The GND considers strain-gradient and thus renders the model size-dependent. The model is calibrated using experimental data from published refereed literature for simple shear deformation of single crystalline pure aluminum alloy and uniaxial tension of polycrystalline Aluminum 3003-H18 alloy. The model also considers the tension-compression asymmetry in case the model is applied for deformation processes in hexagonal close packed pure Titanium and its alloy counterparts which will be investigated further in our proposed research program. One of the significant macroscopic contributions from this model development is to successfully accommodate the elasto-plastic contact problem involved in UC. The model also incorporates various local and global effects such as friction, thermal softening, acoustic softening, surface texture of the sonotrode and initial mating surfaces and presence of oxide-scale at the mating surfaces which further contribute significantly specifically to the grain substructure evolution at the interface and to the anisotropic bulk deformation away from the interface during UC in general. The model results have been predicted for Al-3003 H-18 alloy undergoing UC. A good agreement between the experimental and simulated results has been observed for the evolution of linear weld density and anisotropic global strengths macroscopically. Similarly, microscopic observations such as embrittlement due to grain substructure evolution and broken oxide layer at the UC interface has been also demonstrated by the simulation.

null

['Göynük, T.', 'Onem, O.U.', 'Yasa, E.', 'Karakaya, I.']

2024-03-25T23:33:57Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124338', 'https://doi.org/10.26153/tsw/50946']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['vacuum brazing', '17-4PH stainless steel', 'BNi-2 filler material', 'additive manufacturing']

DISSIMILAR VACUUM BRAZING OF ADDITIVE MANUFACTURED 17-4PH STAINLESS STEEL TO CONVENTIONAL 304 AND 17-4 STAINLESS STEEL BY BNI-2 BRAZING FILLER MATERIAL

Conference paper

https://repositories.lib.utexas.edu//bitstreams/97ae3324-b4ce-458e-9a78-02e4745649ea/download

University of Texas at Austin

Vacuum brazing process of 17-4PH stainless steel, which was manufactured using additive manufacturing, as well as conventional AISI304 and 17-4PH stainless steel alloys was investigated. The brazing process was conducted at 1050°C for 20 minutes under 10-6 Torr, using BNi-2 filler material. Various aspects of the vacuum brazed parts were analyzed, including their microstructure, wetting behavior and mechanical strength. To evaluate the wetting behavior, the contact angle and wetted area were measured using optical microscopy. The microstructures were examined using Scanning Electron Microscopy and Energy Dispersive Spectroscopy techniques. Additionally, tensile testing was performed on the joints to assess the influence of surface roughness and brazing of different materials on the strength of the brazed parts.

null

['Lefky, Christopher S.', 'Nassar, Abdalla R.', 'Simpson, Timothy', 'Hildreth, Owen J.']

2021-10-28T20:57:04Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89698

eng

2016 International Solid Freeform Fabrication Symposium

Open

['direct energy deposition', 'powder bed fusion', 'dissolvable metal supports', 'metal supports', 'chemical stability', 'electrochemical stability']

Dissolvable Metal Supports for Printed Metal Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8247faaa-1218-4dcc-8159-1fe6cab92d5a/download

University of Texas at Austin

Temporary support structures are an inconvenient necessity in Direct Energy Deposition (DED) and Powder Bed Fusion (PBF) printed metal parts. Used to reduce thermal distortion and brace large overhands, support structures often require post-print machining operations to remove, adding costs and processing delays. This preliminary work demonstrates that soluble, sacrificial metal supports can be fabricated in DED and PBF printers by taking advantage of small differences in the chemical and electrochemical stability between different metallic alloys. For DED printing, we demonstrate this process by printing stainless steel bridge structure with 90˚ overhang and printed carbon steel acting as a sacrificial support. For PBF printing, a PBF printed stainless steel part was first printed and then carburized to reduce the free chromium at the surface. Since the support/component interface is only ~100 μm in size, this interface becomes highly susceptible to chemical and electrochemical dissolution. In both cases, the component was separated from the supports in a solution of nitric acid and KCl under mild electrochemical bias. No machining, grinding, or finishing operations were required to remove the metallic supports. These novel approaches introduce new capabilities to additive manufacturing that will drastically reduce the post-processing needed for 3D printed metal components.

null

['Hlifka, Brian M.', 'Kinzel, Edward C.']

2024-03-26T20:43:09Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124403', 'https://doi.org/10.26153/tsw/51011']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'optical fiber', 'fused filament fabrication']

Distributed Optical Fiber Testing for Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e43ff7c0-7569-4bac-bb08-fa813e4d6fdb/download

University of Texas at Austin

This paper explores optical fiber's use for in-situ inspection of additive manufacturing. Single-mode SMF-28 optical fiber can be placed on the build plate to monitor the printing process or embedded in the part. Distributed measurements using optical backscattering reflectometry (OBR) resolve the strain along the optical fiber and the temperature. OBR-enabled sensing is demonstrated for the fused filament fabrication (FFF) process. The small diameter (0.125 mm) of SMF-28 lends itself to embedding in FFF prints. This enables laying the fiber into the part, which provides continued sensing for the details in use. Knowledge of the process and the fiber arrangement allows heating from the deposition head to be distinguished from stress-driven strain. Calibration of the fiber arrangement is discussed, as well as a comparison with process modeling.

null

['Brackett, D.', 'Ashcroft, I.', 'Hague, R.']

2021-10-05T14:55:31Z

8/17/11

Mechanical Engineering

null

['https://hdl.handle.net/2152/88386', 'http://dx.doi.org/10.26153/tsw/15325']

eng

2011 International Solid Freeform Fabrication Symposium

Open

['lattice cells', 'tetrahedral cells', 'dithering method', 'error diffusion', 'additive manufacturing']

A Dithering Based Method to Generate Variable Volume Lattice Cells for Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/eb3b7811-a88f-48c7-a3f1-032427bd0e9a/download

University of Texas at Austin

This paper covers the principles of a novel method to efficiently spatially vary the size of tetrahedral cells of a lattice structure, based upon finite element analysis stress results. A dithering method, specifically error diffusion, is used to represent a grayscale stress fringe with variably spaced black dots. This enables linkage of the spacing between lattice cell vertices to stress level thereby providing a functional variation in cell density. This method is demonstrated with a simple test case in 2D and the steps involved for extension to 3D are described.

null

['Nyrhilä, Olli', 'Kotila, Juha', 'Latikka, Maria', 'Hänninen, Jouni', 'Syvänen, Tatu']

2020-03-09T15:18:35Z

2007

Mechanical Engineering

null

['https://hdl.handle.net/2152/80195', 'http://dx.doi.org/10.26153/tsw/7214']

eng

2007 International Solid Freeform Fabrication Symposium

Open

Direct Metal Laser Sintering

DMLS and Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2c42d9ba-1e5b-4812-a578-e543691d0d0c/download

null

Direct Metal Laser Sintering (DMLS) has been used for manufacturing prototypes, functional metal components and prototype tools for more than 10 years. During this period the technology has advanced to a level where direct production of complex metallic parts for various applications is everyday life and manufacturing with its various challenges is its main target. The shift from prototyping to production requires changes in the technology and also in the organizations taking part in the shift. This paper presents the latest status of the DMLS technology and materials development trends for different application areas using EOSINT M270 laser sintering machine. Commercially launched materials include presently biomedical materials like Titanium and Cobalt Chrome alloys, ultra high strength Maraging Steel alloy, Stainless Steels and other high-end engineering materials. In addition, there are many materials which have been developed for evaluation purposes, waiting for industrial applications.

null

['Ray, Nachiketa', 'Bisht, Manisha', 'Thijs, Lore', 'Van Vaerenbergh, Jonas', 'Coeck, Sam']

2021-11-15T22:33:04Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90297', 'http://dx.doi.org/10.26153/tsw/17218']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['laser powder bed fusion', 'Ti-6Al-4V', 'process optimization', 'monitoring', 'X-ray CT']

DMP Monitoring as a Process Optimization Tool for Direct Metal Printing (DMP) of Ti6Al-4V

Conference paper

https://repositories.lib.utexas.edu//bitstreams/38eaf755-bb4f-4bf0-8c6d-64316922eaba/download

University of Texas at Austin

Metal Additive Manufacturing (AM) has evolved as a production technique for rapid prototyping as well as high volume precision manufacturing. In this work, DMP Monitoring, a new feature of 3D Systems’ direct metal printer, ProX® DMP 320 has been used as a tool for process parameter optimization. The effect of the variations of process parameters like layer thickness, laser power, scan speed and hatch spacing on the physical and mechanical properties of the additively manufactured Ti-6Al-4V samples have been investigated. In addition to the conventional post-processing evaluation methods like Archimedes’ density, X-ray CT and tensile testing, new in-situ process monitoring tools are assessed and compared with the traditional evaluation methods.

null

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

2019-02-20T17:43:24Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73456', 'http://dx.doi.org/10.26153/tsw/608']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['RP', 'PC-based controllers']

Domain Decomposition and Space Filling Curves in Toolpath Planning and Generation

Conference paper

https://repositories.lib.utexas.edu//bitstreams/57ac4954-5e4e-4261-85f1-86f57cbe1e60/download

null

Ever increasing computer performance, along with significant developments in CADI CAM technology and high precision digital motion controllers lead to rapid and significant developments in the field ofrapid prototypingjfabrication. Together, these elements offer a wide range of possible approaches in the toolpath planning issue; two main sets have been analyzed and applied to Fused Deposition Modeling process. Domain decomposition is a frequently used technique in computational methods. Within the context of present study, this approach is used to divide arbitrary layer geometries into smaller regions of simpler shape. A foreseeable advantage in such an approach is maximizing strength characteristics through thermal management. This is achieved by utilizing space filling curves which are mathematical entities that offer the possibility of building a wide range of structures, covering the surface of a single layer with one continuous curve. To evaluate the proposed concepts, ABS structures and ceramic green bodies have been successfully built.

null

['Williams, Glen', 'Baldwin, Martha', 'Simpson, Timothy W.', 'Meisel, Nicholas A.', 'McComb, Christopher']

2024-03-27T03:20:54Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124462', 'https://doi.org/10.26153/tsw/51070']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['machine learning', 'additive manufacturing', 'data augmentation']

Dreaming of Data: Examining Data Augmentation for Machine Learning in Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7019185b-6aa7-4877-99ed-93c429809faf/download

University of Texas at Austin

The data generated during additive manufacturing (AM) practice can be used to train machine learning (ML) tools to reduce defects, optimize mechanical properties, or increase efficiency. In addition to the size of the repository, emerging research shows that other characteristics of the data also impact suitability of the data for AM-ML application. What should be done in cases for which the data in too small, too homogeneous, or otherwise insufficient? Data augmentation techniques present a solution, offering automated methods for increasing the quality of data. However, many of these techniques were developed for machine vision tasks, and hence their suitability for AM data has not been verified. In this study, several data augmentation techniques are applied to synthetic design repositories to characterize if and to what degree they enhance their performance as ML training sets. We discuss the comparative advantage of these data augmentation techniques across several canonical AM-ML tasks.

null

['Chianrabutra, S.', 'Mellor, B.G.', 'Yang, S.']

2021-10-12T20:03:04Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88728', 'http://dx.doi.org/10.26153/tsw/15662']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['material delivery device', 'dry powder', 'dry powder printing', 'multiple material additive manufacturing', 'additive manufacturing']

A Dry Powder Material Delivery Device for Multiple Material Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/187aa596-ba26-44b8-9331-d1188c05608a/download

University of Texas at Austin

This research is to develop a novel material delivery device for a next generation additive manufacturing system which is capable of directly manufacturing objects by depositing several materials layer by layer. The successful deposition of multiple material layers by using this novel dry powder printing technique reveals its great potential as a means of incorporating multiple materials in the traditional additive manufacturing process since this technology is suitable for a wide range of materials and it has the capability to manufacture 2D layers composed of multiple materials. This paper will outline the basics of the dry powder printing technology and present and discuss selected experimental studies from our research.

null

['Lu, Xuesong', 'Yang, Shoufeng', 'Chen, Lifeng', 'Evans, Julian R. G.']

2020-03-05T19:39:22Z

2006

Mechanical Engineering

null

['https://hdl.handle.net/2152/80147', 'http://dx.doi.org/10.26153/tsw/7168']

eng

2006 International Solid Freeform Fabrication Symposium

Open

selective laser sintering

Dry Powder Microfeeding System for Solid Freeform Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/48c2971b-5da9-466c-ba85-951a1556c331/download

null

Second generation SFF techniques allow both composition and shape to be downloaded directly from a computer file so that 3D functionally graded materials (FGM) can be assembled. Methods for multi-material deposition are also needed in combinatorial research, colour management and pharmaceutical dosing. In this work, computer-controlled microfeeding systems using ultrasonic vibration of a capillary were built. A wide range of stable flow rate control and switching control were achieved in the acoustic vibration system, and uniform powder doses were obtained in the ultrasonic system. The experimental results show that the nozzle diameter, transmission fluid depth, waveforms, voltage amplitude, frequency and oscillation duration all influence the dose mass. Among these factors, the nozzle diameter, voltage amplitude and oscillation duration can be used to control the dose mass. Raster printing of patterns with various resolution and dot size are demonstrated.

null

['Glazer, M.', 'Vail, N.K.', 'Barlow, J.W.']

2018-05-03T19:58:29Z

1993

Mechanical Engineering

doi:10.15781/T2057D92D

http://hdl.handle.net/2152/65076

null

1993 International Solid Freeform Fabrication Symposium

Open

['Alumina', 'Silica Colloid', 'Drying']

Drying of Colloidal Binder Infiltrated Ceramic Green Parts Produced by Selective Laser Sintering™

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f217e37f-af94-4dd4-b254-43ab0a04f798/download

null

Colloidal ceramic binders have been used to strengthen ceramic green shapes produced by Selective Laser Sintering. This paper focuses on the effectiveness of the colloid infiltration with respect to the physical properties of the colloidal binder. Mass gains, strength gains, and dimensional changes resulting from infiltration were monitored. Controlled drying experiments were conducted to predict the factors influencing drying times for complex shapes.

null

['Marshall, G.', 'Young, W.J. Jr', 'Shamsaei, N.', 'Craig, J.', 'Wakeman, T.', 'Thompson, S.M.']

2021-10-19T19:05:58Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89325

eng

2014 International Solid Freeform Fabrication Symposium

Open

['Direct Laser Deposition', 'Laser Engineered Net Shaping', 'thermographic monitoring', 'dual monitoring', 'Ti-6Al-4V', 'titanium cylinders']

Dual Thermographic Monitoring of Ti-6Al-4V Cylinders During Direct Laser Deposition

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2a02e019-64e6-454c-a58b-b41b54856ce4/download

University of Texas at Austin

Understanding the thermal phenomena associated with Direct Laser Deposition (DLD) is necessary to begin manipulating fabricated part properties. In this study, a thermally monitored Laser Engineered Net Shaping (LENS) system is used with time-invariant (uncontrolled) build parameters to construct Ti-6Al-4V cylinders with two different build paths. Both paths utilize a circular contour with serpentine hatch fill; however, successive layer patterns are varied and the effects compared between 90° and 120° angular pattern shifts. During fabrication, the part’s thermal history and melt pool temperature are recorded via an in-chamber infrared (IR) camera and a dual-wavelength (DW) pyrometer, respectively. These tools are used for non-destructive thermographic inspection (NTI) of the part to ensure target quality and/or microstructure. A unique calibration method for the IR camera utilizing the DW pyrometer data is presented and a calibration correction factor was utilized for high temperature ranges. The melt pool was found to be 40-50% superheated reaching temperatures up to 2500 ºC at times. Temperature characteristics of two different layers were compared for different hatching patters, and the results show that for a given point in time, maximum temperatures can vary based on laser raster. Temperature gradients varied and peaked at about 1000 ºC/mm along the diameter of the small rods. This can lead to anisotropy in microstructural and mechanical properties allowing for unique property growth per build path. Cooling rates within the melt pool appear to increase as maximum melt pool temperature increases, for instance, from 16,000 ºC/s – 41,000 ºC/s.

null

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

2021-09-29T22:43:24Z

9/23/10

Mechanical Engineering

null

['https://hdl.handle.net/2152/88223', 'http://dx.doi.org/10.26153/tsw/15164']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'dual-material minimum-weight structures', 'ultrasonic consolidation', 'multi-material', 'fabrication']

Dual-Material Minimum Weight Structures Fabrication Using Ultrasonic Consolidation

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ca8fe7b6-0f96-4e99-884e-12e12ff521e1/download

University of Texas at Austin

The multi-material capability of additive manufacturing (AM) processes has created opportunities for structural designs that would otherwise be impossible. This work involves the development of a methodology for fabricating dual-material minimum-weight structures using ultrasonic consolidation (UC). Sample structures were designed, fabricated and tested for load carrying capabilities. Analyses of results show that dual-material minimum weight structures made of Al3003/MetPreg® and Al3003/Ti composite material members can withstand significantly higher strain energy densities up to the point of failure than similar structures made of Al 3003 alone. This is an indication that UC can be effectively used to fabricate multi-material structures for real life applications.

null

['Yigit, Ismail Enes', 'Lazoglu, Ismail']

2021-11-18T18:35:35Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90460', 'http://dx.doi.org/10.26153/tsw/17381']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['support structures', 'dynamic', 'additive manufacturing']

Dynamic Build Bed for Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/416d24c3-012a-4c41-8581-8fd892817841/download

University of Texas at Austin

Compared to subtractive manufacturing, additive manufacturing generally has low material waste. However, models with large overhangs require manufacturing of support structures which ends up as waste material. This paper proposes the use of a dynamic build bed for reducing support structures. The bed consists of an array of actuated pins which move in the build orientation. Each pin can be individually moved to the correct height for supporting the given model. Two separate applications of the build bed are investigated. In the first application, the dynamic build bed is used as support structures in deposition-based AM methods. The pins individually raise out of the build bed to support the overhang geometry at the given deposition height. The second application is in powder-based AM methods. In the second application, the pins are used to fill the space of the powder where the geometry will not occupy. The pins are individually lowered in the build orientation to make space for a new powder layer. Thus, saving excessive deposition of powder.

null

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

2021-11-18T17:30:19Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90438', 'http://dx.doi.org/10.26153/tsw/17359']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['defect detection', 'FEA simulation', 'additive manufacturing', 'internal defects']

Dynamic Defect Detection in Additively Manufactured Parts using FEA Simulation

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9cbfb33d-3673-4751-a0ba-c510578f574d/download

University of Texas at Austin

The goal of this paper is to evaluate internal defects in additively manufactured (AM) parts using FEA simulation. The resonant frequencies of parts are determined by the stiffness and mass involved in the mode shape at each resonant frequency. Voids in AM parts will change the stiffness and mass therefore shift the resonant frequencies from nominal. This paper will investigate the use of FEA to determine how much a void size, shape, and location will change the resonant frequencies. Along with where the optimal input and response locations are in order to find these frequency changes. The AM part evaluated in this work includes a common tensile bar and hammer shaped part evaluated individually and as a set of parts that are still attached to the build plate.

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

['Pan, Yayue', 'Dagli, Chintan']

2021-10-19T19:01:18Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89324

eng

2014 International Solid Freeform Fabrication Symposium

Open

['Additive Manufacturing', 'vat photopolymerization', 'stereolithography', 'resolution control', 'build size']

Dynamic Resolution Control in a Laser Projection Based Stereolithography System

Conference paper

https://repositories.lib.utexas.edu//bitstreams/59fbbbab-46c3-4d31-aa6b-4c82162c7915/download

University of Texas at Austin

In a typical Additive Manufacturing system, it is critical to make a trade-off between the resolution and build area for applications in which varied dimensional sizes, feature sizes, and accuracies are desired. The lack of the capability in adjusting resolution dynamically during building processes limits the use of AM in fabricating complex structures with big layer areas and small features. In this paper, a novel AM system with dynamic resolution control by integrating a laser projection in vat photopolymerization process is presented. Theoretical models and parameter characterizations are presented for the developed AM system. Accordingly, the process planning and mask image planning approaches for fabricating models with varied dimensional sizes and feature sizes have been developed. Multiple test cases based on various types of structures have been performed.

null

['Terrazas, C.A.', 'Gaytan, S.M.', 'Mireles, J.', 'Frigola, P.', 'Espalin, D.', 'Wicker, R.B.']

2021-10-13T20:17:37Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88776', 'http://dx.doi.org/10.26153/tsw/15710']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['high purity niobium', 'superconducting radio frequency', 'electron beam melting', 'additive manufacturing']

EBM Fabrication and Characterization of High Purity Niobium for Superconductor Applications

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d11406f8-a4ff-4985-90ab-8c210fcdcf9d/download

University of Texas at Austin

Superconducting radio frequency (SRF) cavities are used to accelerate charged particles to near the speed of light for elemental studies. Currently, SRF cavities are typically fabricated using different forming processes including deep-drawing and spinning to mechanically shape niobium into the desired geometry. This research presents the development of processing parameters for high purity niobium (powder size range of 25-125μm) using electron beam melting additive manufacturing technology. Fabrication parameters were improved to obtain dense parts in a time-efficient manner. A specific procedure was used to maintain powder purity, and powder chemistry was monitored at different stages of fabrication. In addition, a series of experiments were performed to obtain 99.9% dense parts and a maximum building height of ~85mm.

null

['Post, B.K.', 'Lind, R.F.', 'Lloyd, P.D.', 'Kunc, V.', 'Linhal, J.M.', 'Love, L.J.']

2021-10-28T15:36:23Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89664

eng

2016 International Solid Freeform Fabrication Symposium

Open

['economics', 'processing time', 'fused deposition modeling', 'BAAM', 'additive manufacturing']

The Economics of Big Area Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/37595a23-1b45-46e4-bed7-82026e24d8b6/download

University of Texas at Austin

Case studies on the economics of Additive Manufacturing (AM) suggest that processing time is the dominant cost in manufacturing. Most additive processes have similar performance metrics: small part sizes, low production rates and expensive feedstocks. Big Area Additive Manufacturing is based on transitioning polymer extrusion technology from a wire to a pellet feedstock. Utilizing pellets significantly increases deposition speed and lowers material cost by utilizing low cost injection molding feedstock. The use of carbon fiber reinforced polymers eliminates the need for a heated chamber, significantly reducing machine power requirements and size constraints. We hypothesize that the increase in productivity coupled with decrease in feedstock and energy costs will enable AM to become more competitive with conventional manufacturing processes for many applications. As a test case, we compare the cost of using traditional fused deposition modeling (FDM) with BAAM for additively manufacturing composite tooling.

null

['Martof, Ashley', 'Gullapalli, Ram', 'Kelly, Jon', 'Rea, Allison', 'Lamoncha, Brandon', 'Walker, Jason M.', 'Conner, Brett', 'MacDonald, Eric']

2021-11-09T14:39:15Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90082', 'http://dx.doi.org/10.26153/tsw/17003']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['3D printing', 'sand molds', 'sand casting', 'economics', 'CAD models', 'additive manufacturing']

Economies of Complexity of 3D Printed Sand Molds for Casting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/278b71cd-cfa5-405c-9b1d-861608150868/download

University of Texas at Austin

Additive Manufacturing (more commonly referred to as 3D printing) is resulting in a metamorphosis of the sand casting industry as 3D printed sand molds enable castings of unmatched geometric complexity. The manifold benefits of these molds include: (1) the integration of structural elements such as periodic lattices in order to optimize weight versus strength; (2) the structural inclusion of unique features such as embossed part numbers and/or other details of the production history; and (3) complex geometries that generate new casting applications not possible previously. Additive Manufacturing is often described as providing “complexity for free”, which may not be entirely precise but generally holds true and the identification of castings that are sufficiently complex to benefit from 3D printing is generally left to the intuition of the designer or foundry. New software tools are necessary for foundries to discover opportunities in which the additional costs of 3D printing are compensated by the benefits of increased structural complexity. This paper describes a complexity evaluation tool that scores CAD models to determine the most economical casting approach based on slicing and 2D geometry evaluation. The three potential outcomes include (1) traditional sand casting, (2) AM-enabled sand casting and (3) a hybrid of the two with 3D printed cores in traditional casting flasks. Several case studies are described and evaluated.

null

['Mohammed, Mazher Iqbal', 'Das, Anirudra', 'Gomez-Kervin, Eli', 'Wilson, Daniel', 'Gibson, Ian']

2021-11-02T18:24:08Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89859

eng

2017 International Solid Freeform Fabrication Symposium

Open

['3D printing', 'recycling', 'FDM', 'EcoPrinting', 'ABS']

EcoPrinting: Investigating the Use of 100% Recycled Acrylonitrile Butadiene Styrene (ABS) for Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/77b0e111-6ab9-4655-9a12-8f51b4cc0a65/download

University of Texas at Austin

Many commonly found polymers have the potential to be recycled, such as Acrylonitrile Butadiene Styrene (ABS), a prevalent 3D printing material. In this study we examine the potential of using 100% recycled ABS to form filaments for use in Fused Deposition Modelling (FDM) 3D printing. We then characterise the resulting changes in the printing quality and mechanical properties, over a single recycling cycle. We found that ABS can undergo recycling and reforming into consistent printer filaments without the addition of virgin material. However, notable changesin polymer characteristics were observed, reflected by degradation in mechanical properties during tensile tests and a decrease in the polymer melt flow, which required reduced raster speed to achieve repeatable prints. Despite these limitations, we demonstrate that recycling and reprinting is possible with acceptable loss of material integrity, and could provide unique opportunities for sustainable use of waste ABS using 3D printing technology.

null

['Ippolito, R.', 'Iuliano, L.', 'Gatto, A.']

2018-11-09T16:52:33Z

1996

Mechanical Engineering

doi:10.15781/T25718739

http://hdl.handle.net/2152/69937

eng

1996 International Solid Freeform Fabrication Symposium

Open

['SFF', 'EDM', 'SEM microscope']

EDM Tooling by Solid Freeform Fabrication & Electroplating Techniques

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6fd3db20-d2ee-4b90-8933-2c3af3b1e573/download

null

The term "Rapid Tooling" refers to the rapid creation of tools in much the same way as Solid Freeform Fabrication (SFF) means the rapid creation of models. This revolutionary approach offers both designers and manufacturers attractive advantages in the form of time compression and cost reduction. Timesaving is of vital significance in the production of EDM electrodes for the fabrication ofmoulds and dies. The employment ofSFF and electroplating for this purpose is described. The performances of these new type of electrodes were compared with those obtained conventionally in terms of dimensional tolerances, surface roughness and working time. The surfaces ofboth electrodes and workpieces were also examined by SEM microscope.

null

Yang, Li

2021-11-08T23:33:04Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90077', 'http://dx.doi.org/10.26153/tsw/16998']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing education', 'additive manufacturing', 'education', 'literature review', 'mini-research projects', 'design competitions']

Education of Additive Manufacturing- An Attempt to Inspire Research

Conference paper

https://repositories.lib.utexas.edu//bitstreams/952490fa-5343-4c8c-b3d7-c26783035fd5/download

University of Texas at Austin

Although additive manufacturing technologies have undergone significant development in recent years, significant challenges remain in the understanding of the physics of the processes as well as many other aspects. Therefore, in the education of the next generation AM workforce, beside the instruction of existing AM knowledge, it is also of critical importance that the state-of-the-art research subjects and concepts are made aware to the students. In various classroom and lab setups at University of Louisville, contemporary AM research subjects are introduced to students via various tools including self-guided literature review, mini-research projects and design competitions. Through literature review based studies the students not only become aware of various research subjects, but also have the opportunity to practice critical analysis skills with new AM knowledge. Through the mini-research and the design competition project-based learning processes, the students not only gain hands-on experiences with AM practice but also learn about the research methodologies employed with various AM research subjects.

null

['Cohen, Adam', 'Zhang, Gang', 'Tseng, Fan-Gang', 'Mansfeld, Florian', 'Frodis, Uri', 'Will, Peter']

2019-02-19T19:51:59Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73438', 'http://dx.doi.org/10.26153/tsw/590']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['Microfabrication', 'micromachining']

EFAB: Batch Production of Functional, Fully-Dense Metal Parts with Micron-Scale Features

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7b3b396e-2270-4378-8db4-de74180b7153/download

null

EFAB (Electrochemical FABrication) is a new SFF process with the potential to economically fabricate prototypes or mass production quantities of functional, mesoscale-microscale parts and mechanisms. EFAB generates an entire layer simultaneously-versus serially, as with most SFF. Based on electrodeposition, EFAB allows ultra-thin layers (2-10 microns, or even submicron) that minimize stairsteps, and generates a net-shape, fully-dense metal structure that can be homogeneous and isotropic. Minimum feature width is approximately 25 microns, and can be reduced further. EFAB can be used to manufacture micromachines and microelectromechanical systems (MEMS), offering significant advantages over current processes: e.g., true 3-D geometry, IC compatibility, low capital investment, and process automation.

null

['Bontha, Srikanth', 'Klingbeil, Nathan W.']

2020-03-02T15:33:51Z

2006

Mechanical Engineering

null

['https://hdl.handle.net/2152/80134', 'http://dx.doi.org/10.26153/tsw/7155']

eng

2006 International Solid Freeform Fabrication Symposium

Open

laser-based material deposition processes

Effect of a Distributed Heat Source on Melt Pool Geometry and Microstructure in Beam-Based Solid Freeform Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c687e426-972e-4efb-a042-cf2406bc5915/download

null

The ability to control geometric and mechanical properties of parts fabricated using laser-based manufacturing processes requires an understanding and control of melt pool geometry and microstructure. With the development of electron beam manufacturing or future beam-based deposition processes, the user may have more control over the distribution of incident energy, so that beam width becomes a potential process variable. As such, the focus of this work is the effect of a distributed heat source on melt pool geometry (length and depth) and the thermal conditions controlling microstructure (cooling rates and thermal gradients) in beam-based solid freeform fabrication. Previous work by the authors has employed the Rosenthal solution for a moving point heat source to determine the effects of process variables (laser power and velocity) on solidification cooling rates and thermal gradients controlling microstructure (grain size and morphology) in laser-deposited materials. Through numerical superposition of the Rosenthal solution, the current work extends the approach to include the effects of a distributed heat source for both 2-D thinwall and bulky 3-D geometries. Results suggest that intentional variations in beam width could potentially enable significant changes in melt pool geometry without affecting microstructure.

null

['Silwal, Bishal', 'Gerdmann, Christopher', 'Migues, Stephen', 'Kardel, Kamram', 'Xu, Shaowen', 'Durrence, Andrew']

2021-11-04T14:14:47Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89966

eng

2017 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'welding arc', 'GTAW', 'ABAM', 'maraging steel', 'PBF']

The Effect of Arc-Based Direct Metal Energy Deposition of PBF Maraging Steel

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b776e4f6-8235-4bac-89ad-3f11fe1edbe0/download

University of Texas at Austin

With the growing demand of metal based additive manufacturing it is inevitable that the additively manufactured parts will be used in consolidation with different manufacturing process. Arc based additive manufacturing is a process used to produce three-dimensional structure using welding arc as a power source. Powder Bed Fusion (PBF) is an additive manufacturing process using laser power to generate a three dimensional structure. In this paper, the effect of direct energy deposition on the PBF has been investigated. The microstructure changes and the melting region are characterized. A computational fluid dynamics model is used to predict the melt region and temperature in PBF.

null

['Kolan, Krishna C.R.', 'Leu, Ming C.', 'Hilmas, Gregory E.', 'Comte, Taylor']

2021-10-11T22:55:21Z

2013

Mechanical Engineering

null

['https://hdl.handle.net/2152/88676', 'http://dx.doi.org/10.26153/tsw/15610']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['selective laser sintering', 'porosity', 'architecture', 'bone scaffolds', 'borate glass scaffolds', 'bone repair', 'bone replacement']

Effect of Architecture and Porosity on Mechanical Properties of Borate Glass Scaffolds Made by Selective Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ed1fa2d6-44e9-44f6-b082-bae986ab941a/download

University of Texas at Austin

The porosity and architecture of bone scaffolds, intended for use in bone repair or replacement, are two of the most important parameters in the field of bone tissue engineering. The two parameters not only affect the mechanical properties of the scaffolds but also aid in determining the amount of bone regeneration after implantation. Scaffolds with five different architectures and four porosity levels were fabricated using borate bioactive glass (13–93B3) using the selective laser sintering (SLS) process. The pore size of the scaffolds varied from 400 to 1300 µm. The compressive strength of the scaffolds varied from 1.7 to 15.5 MPa for porosities ranging from 60 to 30%, respectively, for the different architectures. Scaffolds were soaked in a simulated body fluid (SBF) for one week to measure the variation in mechanical properties. The formation of the Hydroxyapatite and in-vitro results are provided and discussed.

null

['Bai, Yun', 'Wagner, Grady', 'Williams, Christopher B.']

2021-10-20T22:30:03Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89376

eng

2015 International Solid Freeform Fabrication Symposium

Open

['binder jetting', 'additive manufacturing', 'copper', 'sintering', '3D printing', 'powder metallurgy']

Effect of Bimodal Powder Mixture on Powder Packing Density and Sintered Density in Binder Jetting of Metals

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4f12eafa-bcc3-46a2-bda2-a746b51cfb01/download

University of Texas at Austin

The Binder Jetting Additive Manufacturing process provides an economical and scalable means of fabricating complex metal parts from a wide variety of materials. However, the performance metrics of the resulting sintered parts (e.g., thermal, electrical, and mechanical properties) are typically lower than traditionally manufactured counterparts due to challenges in achieving full theoretical density. This can be attributed to an imposed constraint on particle size and its deleterious effects on powder bed packing density and green part density. To address this issue, the authors explore the use of bimodal powder mixtures to improve the sintered density and material properties within the context of copper parts fabricated by Binder Jetting. The effectiveness of using bimodal powder mixtures in an effort to improve sintered density is studied in terms of particle size distribution and powder packing density.

null

['Torries, Brian', 'Shamsaei, Nima', 'Thompson, Scott']

2021-11-02T13:57:38Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89804

eng

2017 International Solid Freeform Fabrication Symposium

Open

['fatigue', 'fractography', 'build orientation', 'additive manufacturing', 'Ti-6Al-4V']

Effect of Build Orientation on Fatigue Performance of Ti-6Al-4V Parts Fabricated via Laser-Based Powder Bed Fusion

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7902be18-2406-4888-b3b3-c28bfe1e1e72/download

University of Texas at Austin

The effects of build orientation on the fatigue behavior of additively-manufactured Ti-6Al-4V using a Laser-Based Power Bed Fusion (L-PBF) process is investigated. Ti-6Al-4V rods were manufactured in vertical, horizontal, and 45º angle orientations. The specimens were then machined and polished along the gage section in order to reduce the effects of surface roughness on fatigue behavior. Fully-reversed strain-controlled uniaxial fatigue tests were performed at various strain amplitudes with frequencies adjusted to maintain an average constant strain rate throughout testing. Results indicate slight variation in fatigue behavior of specimens fabricated in the different orientations investigated. Fractography was conducted using scanning electron microscopy after mechanical testing in order to investigate the crack initiation sites and determine the defect responsible for the failure. The experimental program utilized and results obtained will be presented and discussed.

null

['Andurkar, M.', 'Prorok, B.C.', 'Thompson, S.M.']

2023-04-05T13:51:10Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117774', 'http://dx.doi.org/10.26153/tsw/44653']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Selective Laser Melting', 'Nickel Superalloy', 'EBSD', 'Misorientation', 'Microstrain']

Effect of Build Orientation on Residual Stress and Microstructure in Inconel 625 Fabricated via Laser Powder Bed Fusion

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5844b908-74e8-4352-aa8f-d91f704a2e6c/download

null

The reliability of parts produced by Laser Powder Bed Fusion (L-PBF) is still not at a great acceptance level. One of the major defects inherited in parts fabricated from L-PBF is a high level of residual stress. In this study, two build orientations i.e., vertical and diagonal, were used to fabricate Inconel 625 specimens to observe its effects on the residual stress magnitude and grain growth. A novel, Cos-α X-ray diffraction method was used to measure residual stress values along the top surface of the samples. Electron Backscattered Diffraction (EBSD) and kernel average misorientation (KAM) maps were employed to explain residual stress trends and differences between samples. Results indicate that the as-printed vertical sample possessed a higher tensile residual stress (77 ± 15 MPa) compared to the diagonally-printed sample (52 ± 12 MPa). The KAM map of the as-printed vertically oriented sample showed more pronounced local misorientations caused by dislocations compared to the diagonally-printed sample.

null

['Shrestha, Rakish', 'Simsiriwong, Jutima', 'Shamsaei, Nima', 'Thompson, Scott M.', 'Bian, Linkan']

2021-10-27T21:11:01Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89615

eng

2016 International Solid Freeform Fabrication Symposium

Open

['fatigue', 'tensile properties', 'fractography', 'build orientation', 'additive manufacturing']

Effect of Build Orientation on the Fatigue Behavior of Stainless Steel 316L Manufactured via a Laser-Powder Bed Fusion Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3a0efbba-a915-4878-8fbc-4cf4038e9339/download

University of Texas at Austin

n this study, the effects of build orientation on the mechanical properties and fatigue life of stainless steel (SS) 316L, fabricated using the Laser-Powder Bed Fusion (L-PBF) additive manufacturing (AM) process, were investigated under monotonic tensile and uniaxial strain-controlled fully-reversed (R = -1) cyclic loadings. Tensile tests were conducted at a strain rate of 0.001 s-1 , while fatigue tests were performed at strain amplitudes ranging from 0.1% to 0.4% at various frequencies to have a nearly consistent average strain rate in all tests. The comparison between the tensile properties of additively manufactured and wrought SS 316L revealed that L-PBF specimens exhibited higher yield and ultimate tensile stresses as compared to the wrought specimen. In addition, the elongation to failure of the wrought specimen was similar to that of the horizontally oriented specimen, while it was lower relative to specimens built in vertical and diagonal directions. From the strain-life fatigue analysis, the diagonally oriented L-PBF specimens generally exhibited lower fatigue strength as compared to vertical and horizontal specimens. The fractography analysis revealed three major types of defects to be responsible for the crack initiation and failure. These included (1) voids formed due to lack of fusion between the subsequent layers and entrapped gas, (2) inclusions formed due to the partially melted powder particles, and (3) un-melted powder particles clustered near a void.

null

['Mueller, J.', 'Shea, K.']

2021-10-21T15:22:40Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89394

eng

2015 International Solid Freeform Fabrication Symposium

Open

['3D printing', 'inkjet printing', 'build orientation']

The Effect of Build Orientation on the Mechanical Properties in Inkjet 3D Printing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/08945b59-d06e-497d-acbd-dfb3df1b0c5a/download

University of Texas at Austin

It is known that part orientation plays an important role in 3D printing and especially in inkjet 3D printing, where the layers are more distinct than in other processes. Despite many investigations in this direction, previous research focused mainly on build orientations along the three main axes X, Y and Z. For advanced purposes such as optimization, however, it is important to know what happens in combined alignments between the main axes. The authors hypothesize and show that the transition is not linear and that, despite prior studies, the weakest properties are not found when the parts are aligned along the Z direction. The discovered effects can partially be attributed to shear forces in the material, which act between the layers when the parts are not aligned orthogonally to the main axes. To accurately characterize the three-dimensional space, the mixture design method has successfully been introduced to the area of 3D printing and proven to be an efficient tool that can also be used for other processes. With the results of this study, designers and engineers are now able to analyze and predict part properties on a much higher level than before.

null

['Murr, L.E.', 'Gaytan, S.M.', 'Medina, F.', 'Martinez, E.', 'Hernandez, D.H.', 'Martinez, L.', 'Lopez, M.I.', 'Wicker, R.B.', 'Collins, S.']

2021-09-28T20:24:14Z

9/15/09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88174', 'http://dx.doi.org/10.26153/tsw/15115']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'electron beam melting', 'build defects', 'Ti-6Al-4V powder', 'microstructure-mechanical property', 'build examination']

Effect of Build Parameters and Build Geometries on Residual Microstructures and Mechanical Properties of Ti-6Al-4V Components Built by Electron Beam Melting (EBM)

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1c69bcc2-7859-4b01-a387-63fdf9993c5b/download

University of Texas at Austin

In this study, involving additive manufacturing (AM) using electron beam melting (EBM), we have examined build defects which result from beam tripping, porosities (including unmelted or unsintered zones) due to excursions from optimal build parameters (especially variations in melt scan beam current and scan speed), and gas bubbles trapped in atomized Ti-6Al-4V starting powder as well as recycled powder, and retained in the build. At optimized build conditions we have also examined microstructure-mechanical property (hardness, tensile strength, and elongation) variations for multiple rake building and multiple melt scans using optical metallography and scanning and transmission electron microscopy (SEM and TEM). These build variances cause cooling rate variances which promote α-phase growth and variations in dislocation density, as well as α-to-α' (martensite) phase changes, all of which produce some degree of mechanical property variations. These features (especially α-to-α' phase changes) are notable on comparing solid builds in comparison with a variety of mesh arrays where strut dimension and build-element complexities alter the cooling rates in a significant way. We illustrate these microstructure variations with corresponding variations in microindentation hardness measurements made directly on fine mesh (strut) structures. Finally, we have examined Ti-6Al-4V powder chemistries and solid build chemistries which for single-pass melt scans at optimized build conditions are shown to be relatively constant up to 40 cycles of powder reuse with the exception of Al content which was reduced by 10 to 15% in solid builds at optimized conditions. However, Al loss in solid builds approached 25% for multiple (2 and 3) melt scans, while no changes in Ar gas-bubble density were observed with changes in α-phase (grain) width which increased from 3 µm for a single melt scan to 4.5 and 6 µm for 2 and 3 melt scans, respectively. Corresponding Rockwell C-scale (HRC) hardness varied from 37, 36, and 35, respectively; with ultimate tensile strengths exceeding 1.2 GPa at elongations of 12% or higher for this melt scan sequence.

null

['Mason, L.', 'Leu, M.C.']

2021-11-30T21:28:45Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90554', 'http://dx.doi.org/10.26153/tsw/17473']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['ABS', 'lattice structures', 'cell size', 'surface roughness', 'compressive properties', 'fused deposition modeling']

The Effect of Cell Size and Surface Roughness on the Compressive Properties of ABS Lattice Structures Fabricated by Fused Deposition Modeling

Conference paper

https://repositories.lib.utexas.edu//bitstreams/594975b1-f92e-4e0e-98ad-ec6a15571bae/download

University of Texas at Austin

Researchers looking to improve the surface roughness of acrylonitrile butadiene styrene (ABS) parts fabricated by fused deposition modeling (FDM) have determined that acetone smoothing not only achieves improved surface roughness but increases compressive strength as well. However, the sensitivity of ABS parts to acetone smoothing has not been explored. In this study we investigated FDM-fabricated ABS lattice structures of various cell sizes subjected to cold acetone vapor smoothing to determine the combined effect of cell size and acetone smoothing on the compressive properties of the lattice structures. The acetone-smoothed specimens performed better than the as-built specimens in both compression modulus and maximum load, and there was a decrease in those compressive properties with decreasing cell size. The difference between as-built and acetone-smoothed specimens was found to increase with decreasing cell size for the maximum load.

null

['He, Haiyang', 'Pan, Yayue', 'Yu, Xiaoming']

2021-11-04T14:58:50Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89978

eng

2017 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'projection stereolithography', 'surface texture', 'constrained surface']

Effect of Constrained Surface Texturing on Separation Force in Projection Stereolithography

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b1bb203a-0571-4853-9cae-fd5dbf1657ec/download

University of Texas at Austin

In projection stereolithography (SL) processes, the separation of a newly cured layer from the constrained surface is a historical technical barrier and still greatly limits its printable size, process reliability and print speed. This paper presents an approach to reduce the separation force in projection stereolithography (SL) processes by texturing the constrained surface with radial microgroove patterns. Separation forces with conventional smooth constrained surface and textured surface are both modeled. The analytical model suggests that a proper design of micro patterns of the constrained surface is capable of reducing separation forces greatly. Furthermore, a projection SL testbed with online separation force monitoring unit is developed for experimental study. Experimental results verified the effectiveness of micro surface textures in reducing separation forces. Test cases also show that with the help of the proposed textured constrained surface, parts with wide solid cross sections that could not be printed using conventional methods were manufactured successfully. The influence of the textured constrained surface on the printed parts’ surface roughness is studied, a grey scale projection approach is proposed to eliminate the influence and improve the surface quality of printed parts. Hence, the presented methods can help to improve the manufacturing capability of Projection SL processes.

null

['Gong, Haijun', 'Rafi, Khalid', 'Starr, Thomas', 'Stucker, Brent']

2021-10-06T20:21:19Z

8/16/12

Mechanical Engineering

null

['https://hdl.handle.net/2152/88432', 'http://dx.doi.org/10.26153/tsw/15369']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['Selective Laser Melting', 'part defects', 'fatigue performance', 'Ti-6Al-4V']

Effect of Defects on Fatigue Tests of As-Build Ti-6Al-4V Parts Fabricated by Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/81afac47-1c23-4946-b1f7-f28680e0210d/download

University of Texas at Austin

Defects can be found in parts made using Selective Laser Melting (SLM) due to balling effects and other types of localized irregularities. This study investigates how defects affect the fatigue performance of Ti-6Al-4V samples in an SLM as-built surface finish condition. Fatigue samples were built and heat treated for stress relief. In order to investigate the effect of defects, a series of fatigue samples were designed with built-in cylindrical and double-conical defects. Tests were carried out to correlate maximum stress to the number of cycles to failure. Optical and scanning electron micrographs were utilized to compare and analyze crack initiation and propagation characteristics. Based on the results, the influence of defects on fatigue properties is discussed.

null

['Muhammad, Muztahid', 'Shao, Shuai', 'Shamsaei, Nima']

2023-01-25T18:40:43Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117296', 'http://dx.doi.org/10.26153/tsw/44177']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Additive manufacturing', 'Laser powder bed fusion (L-PBF/LB-PBF)', 'Ti-6Al-4V', 'Defects', 'Tensile properties']

Effect of Defects on the Mechanical Properties of Laser Powder Bed Fused Ti-6Al-4V

Conference paper

https://repositories.lib.utexas.edu//bitstreams/67607c26-9a2d-48cd-84fb-d278f34e9646/download

null

Process-induced volumetric defects are inherent to additively manufactured parts. This study investigates the effect of volumetric defects on the tensile properties of the laser powder bed fused (L- PBF) Ti-6Al-4V specimens fabricated with large variations in process parameters (a total of six sets of process parameters). Cylindrical rods of L-PBF Ti-6Al-4V specimens were stress-relieved before removal from plates and machined to tensile specimens. The defect distribution of specimens resulting from each set of process parameters was analyzed using a high-resolution X-ray computed tomography machine. Quasi-static tensile tests were performed at room temperature using a servo-hydraulic MTS machine. Tensile results were correlated with defect statistics. No apparent difference was observed in the yield strength of the L-PBF Ti-6Al-4V specimens despite the large variations in the process parameters resulting in significant differences in defect content. However, a considerable drop in ductility was observed for the specimens fabricated with insufficient energy.

null

['Guo, Nannan', 'Leu, Ming C.']

2021-09-30T18:30:46Z

9/23/10

Mechanical Engineering

null

['https://hdl.handle.net/2152/88272', 'http://dx.doi.org/10.26153/tsw/15213']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['graphite materials', 'bipolar plates', 'Proton Exchange Membrane', 'Selective Laser Sintering', 'layer-by-layer manufacturing', 'complex gas flow channels', 'electrical conductivity', 'flexural strength']

Effect of Different Graphite Materials on Electrical Conductivity and Flexural Strength of Bipolar Plates Fabricated by Selective Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7324bb24-8b98-4583-9b83-1c7d43b10eec/download

University of Texas at Austin

Graphite is an excellent material for bipolar plates used in Proton Exchange Membrane (PEM) fuel cell due to its great chemical resistance, but the brittle nature makes it difficult to manufacture. Selective Laser Sintering (SLS) based on layer-by-layer manufacturing technology can fabricate graphite bipolar plates with complex gas flow channels. To improve the performance of bipolar plates including electrical conductivity and flexural strength, different graphite materials (natural graphite, synthetic graphite, carbon black, and carbon fiber) were investigated to fabricate test samples. These samples then went through post processing including carbonization and infiltration. The results show that bipolar plates with electrical conductivity of 380 S/cm and flexural strength of 40 MPa are obtained from proper combinations of natural graphite and carbon fiber, which are higher than the target values set by the Department of Energy.

null

['Olakanmi, E.O.', 'Sepako, M.', 'Morake, J.', 'Kutua, S.', 'Hoosain, S.E.', 'Pityana, S.L.']

2021-11-11T15:22:48Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90218', 'http://dx.doi.org/10.26153/tsw/17139']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['functionally graded materials', 'FGM', 'laser cladding', 'LC', 'chemical composition', 'titanium aluminide', 'Ti-Al']

Effect of Energy Density on the Consolidation Mechanism and Microstructural Evolution of Laser Cladded Functionally-Graded Composite Ti-Al System

Conference paper

https://repositories.lib.utexas.edu//bitstreams/83d74bdf-5bc9-409c-bbb8-5aefcfd07c78/download

University of Texas at Austin

The engagement of additive manufacturing (AM) technology in developing intermetallic coatings involves additional heat treatment with a view to obtaining desirable microstructure and mechanical properties. This eventually increases the lead time and the manufacturing cost. To address these challenges, this study explores the fabrication of gradient and laminar structures of titanium aluminide (Ti-Al) composite coatings deposited on Ti-6Al-4V substrate via a single step laser cladding (LC). The alterations in microstructural properties, chemical composition and phase analysis of the coatings reinforced with TiC were investigated as a function of laser energy density. Evaluation of the deposited samples reveals that FGM composite clads were fabricated from Ti-Al blended with TiC when LED was set at 17.50 J/mm2 . At the selected LED, a thermo-positive reaction between the constituents’ materials was induced and it resulted in the formation of intermetallic compounds (e.g. Ti2AlC, 𝛾𝛾 and 𝛼𝛼2 matrix phases) with a microhardness more than that of the substrate (Ti-6Al-4V alloy). This study provides new insights on the selection of process parameters for the coating manufacturers while employing low cost- and time-effective LC process for fabricating functional graded Ti-Al coatings.

null

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

2021-11-15T20:53:36Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90268', 'http://dx.doi.org/10.26153/tsw/17189']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['environmental factors', 'simulation', 'Ti-64', 'metal additive manufacturing']

Effect of Environmental Variables on Ti-64 AM Simulation Results

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f4349941-6dfc-443a-8f2a-0eb8aa46fee7/download

University of Texas at Austin

In metal AM the environment is critical and therefore care should be taken to ensure that the simulation matches reality. This paper will investigate the effect that various environmental factors have on the results of the simulation. This will help to determine their importance in the simulation setup. The material properties which relate to this are the convective coefficient and the emissivity. These material properties will be investigated to determine their effect on the outcome of the simulation. In addition to these properties, the size of the substrate will be investigated to determine if any results are altered. Lastly, the ambient temperature will be investigated to determine the effect this has on the simulation results.

null

['Heller, B.P.', 'Smith, D.E.', 'Jack, D.A.']

2021-10-21T18:03:54Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89413

eng

2015 International Solid Freeform Fabrication Symposium

Open

['Fused Deposition Modeling', 'nozzle flow', 'melt flow', 'fiber orientation', 'convergence zone', 'extrudate swell', 'nozzle exit shape']

Effect of Extrudate Swell, Nozzle Shape, and Convergence Zone on Fiber Orientation in Fused Deposition Modeling Nozzle Flow

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b4249cf2-9dd3-49c8-b5a2-4b600b901a6d/download

University of Texas at Austin

Recent advances for improving the mechanical properties of materials used in Fused Deposition Modeling (FDM) include the addition of carbon fibers to the filament feedstock. During processing, the flow field within the polymer melt orients the fiber suspension, which is important to quantify since fiber orientation influences mechanical and thermal properties. This paper presents a computational approach for evaluating polymer melt flow and fiber orientation within a FDM nozzle taking into consideration the converging flow in the nozzle, fluid expansion caused by extrudate swell, and nozzle exit shape. Finite elements are used to evaluate the Stoke’s flow in an axisymmetric nozzle and fiber orientation tensors are evaluated along streamlines within the flow using the Fast Exact Closure and Folgar-Tucker isotropic rotary diffusion. Fiber orientation is shown to increase in the shear-dominated flow through the nozzle, however, alignment is found to decrease in the expansion flow of the die swell.

null

['Davis, Joy E.', 'Klingbeil, Nathan W.']

2021-09-30T14:00:17Z

2010

Mechanical Engineering

null

['https://hdl.handle.net/2152/88253', 'http://dx.doi.org/10.26153/tsw/15194']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['laser beam-based fabrication', 'electron beam-based fabrication', 'additive manufacturing', 'repair applications', 'melt pool geometry', 'microstructure solidification', '3-D structures']

Effect of Free-Edges on Melt Pool Geometry and Solidification Microstructure in Beam-Based Fabrication of Bulky 3-D Structures

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c374c9dc-e6e7-4aec-b726-6393b8ae6a1e/download

University of Texas at Austin

The success of laser and electron beam-based fabrication processes for additive manufacture and repair applications requires the ability to control melt pool geometry while still maintaining a consistent and desirable microstructure. To this end, previous work by the authors has employed point heat source solutions to investigate the effects of process variables (beam power and velocity) on melt pool geometry and solidification microstructure (grain size and morphology) in beam-based fabrication of bulky 3-D structures. However, these results were limited to steady-state conditions away from free-edges. The current work extends the approach to investigate transient behavior in the vicinity of free-edges, and follows the authors’ recent work for 2-D thin-wall geometries [1].

null

['Noble, Christopher James', 'Ellis, Adam', 'Hopkinson, Neil']

2021-10-12T20:42:54Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88736', 'http://dx.doi.org/10.26153/tsw/15670']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['High Speed Sintering', 'Additive Manufacturing', 'ink dosage', 'greyscale', 'part density']

Effect of Greyscale/Print Density on the Properties of High Speed Sintered Nylon 12

Conference paper

https://repositories.lib.utexas.edu//bitstreams/93b126e0-08ae-4581-ad59-6e7765eff171/download

University of Texas at Austin

High Speed Sintering is an Additive Manufacturing process that creates parts by sintering using inkjet and infra-red lamp technology, rather than the laser systems employed in Laser Sintering. This research investigated the effects of altering the dosage of ink (greyscale/print density) on the properties of parts produced. A clear pattern emerges that shows a ‘sweet spot’ for correct dosage of ink to maximise properties. The work also shows that greyscale allows considerable control of part density that could lead to substantial reductions in part mass beyond those that may be achieved by conventional design optimisation approaches employed today.

null

['Zhang, Bin', 'Ham, Kyungmin', 'Shao, Shuai', 'Shamsaei, Nima', 'Thompson, Scott M.']

2021-11-02T13:55:09Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89803

eng

2017 International Solid Freeform Fabrication Symposium

Open

['heat treatment', 'hot isostatic pressing', 'Ti-6Al-4V', 'laser-based powder bed fusion', 'morphology', 'pore size', 'porosity']

Effect of Heat Treatment and Hot Isostatic Pressing on the Morphology and Size of Pores in Additive Manufactured Ti-6Al-4V Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7f21d306-495d-46e3-8de7-e6c345474a7c/download

University of Texas at Austin

Additive manufactured parts suffer from porosity, among other defects. The slit-shaped pores due to lack of fusion are the most detrimental to fatigue and mechanical properties. Their sharp edges generate severe stress concentration and serve as preferred sites for crack initiation. The sharp edges also have low formation energy of surface adatoms, increasing their tendency to spheroidize under elevated temperatures, such as during heat treatment (HT). In hot isostatic pressing (HIP), the combined action of high temperature/pressure also reduces the size of the pores. In this work, HT and HIP were performed on Ti-6Al-4V parts manufactured from laser-based powder bed fusion to investigate the effect of HT and HIP on morphology/size of pores. Using scanning electron microscopy combined with X-ray computed tomography, special attention is paid to the evolution of the shape of the pore1s under controlled exposures to elevated temperature during HT. The results will be used, in our subsequent work, to validate a phase field porosity evolution model based on density functional theory.

null

['Montero Sistiaga, M.L.', 'Nardone, S.', 'Hautfenne, C.', 'Van Humbeeck, J.']

2021-10-26T20:24:42Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89577

eng

2016 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', 'additive manufacturing', '316L', 'heat treatment']

Effect of Heat Treatment of 316L Stainless Steel Produced by Selective Laser Melting (SLM)

Conference paper

https://repositories.lib.utexas.edu//bitstreams/fa96c87e-d1b1-4afc-b22d-b7cfcc564aad/download

University of Texas at Austin

Selective Laser Melting (SLM) shows a big potential within additive manufacturing of metals. The competitive mechanical properties compared to conventional processes as well as the geometry freedom are the main advantages of SLM. 316L stainless steel has been investigated in previous works regarding microstructure and mechanical properties. However, the influence of heat treatments has not been fully reported yet. This work studies the influence of different heat treatments applied to 316L stainless steel produced by SLM. The microstructure evolution was investigated for different conditions. Tensile, Charpy and hardness tests were performed on the as built and heat treated samples.

null

['Nandi, Indrajit', 'Ghiaasiaan, Reza', 'Ahmad, Nabeel', 'Gradl, Paul R.', 'Shamsaei, Nima']

2024-03-25T23:36:30Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124339', 'https://doi.org/10.26153/tsw/50947']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'Monel K500', 'Ni-base superalloys', 'microstructure', 'tensile properties']

Effect of heat treatment on the microstructure and mechanical properties of Monel K500 alloy fabricated via L-PBF and LP-DED

Conference paper

https://repositories.lib.utexas.edu//bitstreams/80a961c1-a24a-43c7-a433-3696372ed16c/download

University of Texas at Austin

This study examines and compares the effect of different heat treatments (HT) on the microstructure and mechanical properties of Monel K500 fabricated using laser powder bed fusion (L-PBF) and laser powder directed energy deposition (LP-DED) technologies. The as-fabricated Monel K500 specimens exhibited dendritic microstructure and elemental micro-segregation due to high cooling rates induced during the fabrication process. The applicability of HT proposed in the literature for wrought Monel K500 was investigated for L-PBF and LP-DED using four different HT procedures involving hot isostatic pressing (HIP), solution annealing (SA), and aging. The mechanical properties of test specimens were evaluated using uniaxial tensile testing at room temperature. The microstructural evolution of test specimens during HT was analyzed using a scanning electron microscope. For all HT conditions investigated, L-PBF Monel K500 specimens consistently displayed higher strength and lower ductility compared to the LP-DED counterparts. The HT procedure involving HIP at 1160°C for 3hr at 100 MPa, SA at 1100°C for 15 min, and three step aging at 610°C for 16 hr, 540°C for 6 hr, and 480°C for 8 hr resulted in highest strength for both L-PBF and LP-DED fabricated Monel K500.

null

['Baig, Shaharyar', 'Shao, Shuai', 'Gradl, Paul R.', 'Shamsaei, Nima']

2023-01-25T18:32:11Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117295', 'http://dx.doi.org/10.26153/tsw/44176']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Additive manufacturing (AM)', 'laser powder bed fusion (L-PBF)', 'Haynes 214', 'microstructure', 'tensile properties']

The Effect of Heat Treatment on the Microstructure and Tensile Properties of Laser Powder Bed Fused (L-PBF)

Conference paper

https://repositories.lib.utexas.edu//bitstreams/114f6dee-e90c-45cc-8a87-04326193fa2f/download

null

The as-fabricated microstructure of Haynes 214 by laser powder bed fusion (L-PBF) is dendritic due to the high cooling rates, which is generally considered undesirable and removed via heat treatments. In this study, the effects of various heat treatments on the microstructure and tensile properties of laser powder bed fused Haynes 214 are investigated. Test specimens were fabricated on a L-PBF system in the vertical orientation. Multi-step heat treatments were performed including stress-relief, hot isostatic pressing, solution annealing and ageing. Examining the microstructures revealed columnar grains in the non-heat treated (NHT) condition with grain growth occurring after stress relief. Room temperature tensile tests showed the lowest strengths in the NHT condition. The highest strengths were seen in the aged condition which was attributed to gamma prime precipitation hardening. Finally, the tensile fracture surfaces indicated ductile failure mode in both the NHT and heat treated conditions with the measured elongation being the highest for NHT and lowest in the aged condition.

null

['Basak, Amrita', 'Das, Suman']

2021-11-02T14:37:56Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89812

eng

2017 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'scanning laser epitaxy', 'SLE', 'nickel-base', 'superalloys', 'CMSX-4', 'heat treatment']

Effect of Heat Treatment on the Microstructures of CMSX-4® Processed Through Scanning Laser Epitaxy (SLE)

Conference paper

https://repositories.lib.utexas.edu//bitstreams/91f48016-61b0-4976-a43e-2cf27ce44840/download

University of Texas at Austin

Engineered components made of superalloys routinely undergo heat treatment procedures to tailor their microstructures and properties. In this study, the effect of heat treatment on the microstructures and microhardness of single-crystal nickel-base superalloy CMSX-4® is investigated. Samples of CMSX-4® are fabricated using scanning laser epitaxy (SLE), a laser powder bed fusion (LPBF)-based additive manufacturing process. Microstructural characterizations of the as-deposited and the heat treated CMSX-4® samples are performed using optical microscopy, scanning electron microscopy, x-ray diffraction, and Vickers microhardness measurements. The results show that the microstructure is homogenized with reductions in the eutectic volume fraction after heat treatment. The microhardness values are also improved upon heat treatment.

This work is sponsored by the Office of Naval Research through grant N00014-14- 1-0658.

null

['Nezhadfar, P.D.', 'Verquin, Benoit', 'Lefebvre, Fabien', 'Reynaud, Christophe', 'Robert, Maxime', 'Shamsaei, Nima']

2021-12-06T22:09:33Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90692', 'http://dx.doi.org/10.26153/tsw/17611']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['metal binder jetting (MBJ)', 'stainless steel', 'microstructure', 'heat treatment', 'tensile']

Effect of Heat Treatment on the Tensile Behavior of 17-4 PH Stainless Steel Additively Manufactured by Metal Binder Jetting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/db0a8a75-44d6-476e-bff9-d04007659344/download

University of Texas at Austin

Metal Binder Jetting (MBJ), a non-fusion-based powder bed additive manufacturing (AM) process, enables the fabrication of complex geometries with minimum residual stresses. Various materials have been successfully manufactured via the MBJ process; however, appropriate post-process heat treatments are required to enhance their mechanical performance as compared to the wrought or other additively manufactured counterparts. This study aims to investigate the effect of post-manufacture heat treatment on the microstructure and mechanical properties of MBJ 17-4 PH stainless steel (SS). Various heat treatment procedures following the standard routes for the wrought 17-4 PH SS are conducted to evaluate their effects on the tensile behavior of MBJ 17-4 PH SS. The mechanical behavior of the MBJ 17-4 PH SS in various heat treatment conditions is discussed based on their corresponding microstructure.

null

['Gusain, Rukesh', 'Gradl, Paul R.', 'Shao, Shuai', 'Shamsaei, Nima']

2024-03-25T23:39:04Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124340', 'https://doi.org/10.26153/tsw/50948']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['LP-DED', 'precipitation hardened stainless steel', 'heat treatment effects', 'cryogenic temperature', 'tensile fracture']

EFFECT OF HEAT TREATMENTS ON THE TENSILE PROPERTIES OF ADDITIVELY MANUFACTURED 15-5 PH STAINLESS STEEL

Conference paper

https://repositories.lib.utexas.edu//bitstreams/90bbabca-5fb3-4592-ad0e-126b1c69e900/download

University of Texas at Austin

This study investigated the effect of post-manufacture heat treatments on the microstructure and mechanical properties of 15-5 PH stainless steel (SS) fabricated by laser powder-directed energy deposition (LPDED). Various heat treatment procedures (CA-H900 and CA-H1150) were conducted to evaluate their effects on the tensile behavior of LP-DED 15-5 PH SS. Scanning electron microscopy was used to characterize the microstructural features and the fracture surfaces. Tensile tests were performed to evaluate the mechanical properties at cryogenic and room temperatures. The mechanical behavior of the LP-DED 15-5 PH SS in different heat treatment conditions is discussed based on their microstructures and fracture surfaces. Reduction in area of CA-H1150 treated specimens after tensile tests was significantly higher than CA-H900 ones, while the ultimate tensile and yield strengths of CA-H900 specimens were higher compared to the CA-H1150 ones. The CA-H1150 specimens had relatively coarser Cu-enriched precipitates, and exhibited greater necking compared to CA-H900 specimens.

null

['Leigh, David K.', 'Bourell, David L.', 'Beaman, Joseph J. Jr']

2021-10-05T13:34:52Z

8/17/11

Mechanical Engineering

null

['https://hdl.handle.net/2152/88368', 'http://dx.doi.org/10.26153/tsw/15307']

eng

2011 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'rapid', 'polyamide', 'Selective Laser Sintering']

Effect of In-Plane Voiding on the Fracture Behavior of Laser Sintered Polyamide

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0cd74f16-8881-4b64-90f8-b8cd4071bbe5/download

University of Texas at Austin

The primary contributors to poor mechanical properties in polyamide materials used during Selective Laser Sintering® are qualified. Methods to quantify the decreased mechanical properties, including Scanning Electron Microscopy (SEM) of fracture surfaces, are compared against each other and against mechanical properties of components fabricated using multiple process parameters. Of primary interest are Ultimate Tensile Strength (UTS) and Elongation at Break (EOB) of tensile specimens fabricated under conditions that produce varying degrees of ductile and brittle fracture.

null

['Beyene, Shiferaw D.', 'Ayalew, Beshah', 'Pilla, Srikanth']

2021-11-10T22:30:36Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90193', 'http://dx.doi.org/10.26153/tsw/17114']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['in-situ compaction', 'UV-induced curing', 'layer-by-layer', 'curing', 'glass fiber', 'fiber-reinforced polymer']

Effect of In-Situ Compaction and UV-Curing on the Performance of Glass Fiber-Reinforced Polymer Composite Cured Layer by Layer

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c484095a-f6ff-425d-adb1-1beaa05bec05/download

University of Texas at Austin

In this paper, the effect of in-situ compaction and UV-induced curing on the performance of fiber-reinforced diglycidyl ether bisphenol A (DGEBA) based epoxy is studied for a layer-by-layer curing process. The optimum percentage of photo-initiator concentration and UV-intensity were obtained by conducting a different experiment for each of them. Fourier Transform Infrared (FTIR) spectroscopy method is used to determine the degree of cure. Then, short beam shear (SBS) test is conducted to measure the inter-laminar shear strength of the cured product under different compaction load. The UV intensity and Photo-initiator concentration were kept constant during the test. The result showed that thick composite parts fabricated with in-situ compaction and UV curing process have showed increased inter-laminar shear strength with increased compaction load up to a certain point. An increase in compaction beyond this point decreased the interlaminar-shear strength.

null

['Kishore, Vidya', 'Nycz, Andrzej', 'Lindahl, John', 'Duty, Chad', 'Carnal, Charles', 'Kunc, Vlastimil']

2021-11-18T18:38:23Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90461', 'http://dx.doi.org/10.26153/tsw/17382']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['infrared preheating', 'mechanical properties', 'z-direction', 'anisotropy', '3D printed parts', 'large-format extrusion additive manufacturing']

Effect of Infrared Preheating on the Mechanical Properties of Large Format 3D Printed Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/53183dcf-bf2e-43a5-ad13-63d3288e6b31/download

University of Texas at Austin

Anisotropy of mechanical properties is characteristic of components printed using processes like extrusion deposition additive manufacturing, wherein the properties along the print direction (x-direction) are superior when compared to the corresponding properties in the build direction (z-direction). This effect, influenced by the bond strength in the z-direction, can be more pronounced for components with longer layer times, as the bottom layers tend cool below the glass transition temperature (Tg) of the material, thereby restricting thermal fusion between the printed layers. The work discussed here builds on the previous work by the authors, demonstrating infrared preheating as a technique to actively control the bond temperature during printing to improve the mechanical properties (z-direction) of parts printed on a large-format extrusion AM system. IR preheating was used on the surface of printed layers just prior to the deposition of the next layer to increase the surface temperature closer to the glass transition temperature. The current study explores the effect of variation in bead surface temperatures (indicative of variations in layer times) prior to and after pre-heating on the mechanical properties in z-direction.

null

['Bandari, Y.K.', 'Lee, Y.S.', 'Nandwana, P.', 'Richardson, B.S.', 'Adediran, A.I.', 'Love, L.J.']

2021-11-09T16:39:11Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90109', 'http://dx.doi.org/10.26153/tsw/17030']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['additive layered manufacturing', '3-D printing', 'direct energy deposition', 'laser metal deposition with wire', 'Ti-6Al-4V', 'laser scanner', 'distortion', 'residual stress']

Effect of Inter-Layer Cooling Time on Distortion and Mechanical Properties in Metal Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/21cc7076-ab8f-4f31-b371-372e5bcd4662/download

University of Texas at Austin

Laser Metal Deposition with wire (LMD-w) is one of the novel Direct Energy Deposition (DED) processes that is gaining the attention of various industries, especially aerospace, due to the potential cost and lead time reductions for complex parts. However, subjects of development include optimization of process parameters (for example laser power, wire feed speed, robotic travel speed, inter-layer cooling time etc.) for large scale adaption of this process. These parameters influence residual stress which potentially results in distortion and subsequent mechanical properties. Inter-layer cooling time is one of the main influences on production volume and is typically used to help control the cooling conditions to mitigate part distortion. Therefore, this paper is aimed at investigating different inter-layer cooling times on distortion and resulting mechanical properties of the parts produced by LMD-w. Distortion of deposited Ti-6Al-4V walls was measured automatically using a laser scanner, which was attached to the robotic arm itself. Finally, suitable recommendations are discussed to optimize the inter-layer cooling time to produce parts with desired mechanical properties.

null

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

2024-03-27T03:52:30Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124477', 'https://doi.org/10.26153/tsw/51085']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['directed energy deposition', 'residual stress', 'inter-layer dwell time', 'high strength steel alloy']

Effect Of Inter-Layer Dwell Time on Residual Stresses in Directed Energy Deposition of High Strength Steel Alloy

Conference paper

https://repositories.lib.utexas.edu//bitstreams/125a716d-b4fe-40d0-922c-860abe98abeb/download

University of Texas at Austin

Adoption of metal additive manufacturing by various industries is being hindered by the presence of residual stresses and distortion in the deposited parts. Large thermal gradients during directed energy deposition often led to residual stresses in the final deposit. Parameter optimization is predominantly used for residual stress mitigation. However, the effect of process parameters is material specific. Current research aims to study the effect of inter-layer dwell time on residual stresses in directed energy deposition of high strength steel alloy. Specimens were deposited at three levels of inter-layer dwell time. Surface as well as bulk residual stresses were measured using X-ray diffraction. Both surface as well as bulk residual stresses were found to increase with an increase in the inter-layer dwell time.

null

['Torries, Brian', 'Shao, Shuai', 'Shamsaei, Nima', 'Thompson, Scott M.']

2021-10-28T19:11:55Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89672

eng

2016 International Solid Freeform Fabrication Symposium

Open

['fatigue', 'fractography', 'tensile properties', 'microstructure', 'geometry effects']

Effect of Inter-Layer Time Interval on the Mechanical Behavior of Direct Laser Deposited Ti-6Al-4V

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2589182d-f6d3-4d40-8cad-dc9787b8c450/download

University of Texas at Austin

Due to its wide applicability in the biomedical and aerospace fields, where unique and/or difficult to machine geometries are required, Ti-6Al-4V continues to be a strong candidate for additive manufacturing. In this study, the effect of inter-layer time interval on the mechanical behavior of Ti-6Al-4V fabricated via Laser Engineered Net Shaping (LENSTM) is investigated. Two sets of specimens were fabricated, each with their own inter-layer time interval, accomplished by depositing either one or two specimens per operation. Tensile tests and fully reversed, strain controlled fatigue tests were conducted on the specimens. Experimental results indicate that specimens fabricated using longer inter-layer time intervals possess a higher ultimate tensile strength, lower ductility, and finer microstructure relative to those fabricated using shorter time intervals. Additionally, specimens fabricated using longer inter-layer time intervals possessed shorter fatigue lives due to presence of more process defects, such as pores and lack of fusion, inherent to additive manufacturing. Such effects are important to consider when producing multi-part assemblies or large parts.

null

['Rafique, Muhammad Musaddique Ali', 'Brandt, Milan', 'Easton, Mark', 'Qiu, Dong', 'Cole, Ivan', 'John, Sabu']

2021-11-10T21:21:30Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90179', 'http://dx.doi.org/10.26153/tsw/17100']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['additive', 'bulk metallic glass', 'composites', 'inoculation', 'phase']

Effect of Laser Additive Manufacturing of Microstructure Evolution of Inoculated Zr47.5Cu45.5Al5Co2 Bulk Metallic Glass Matrix Composites

Conference paper

https://repositories.lib.utexas.edu//bitstreams/02ef9a5d-503d-4050-8620-ee3d4edecd92/download

University of Texas at Austin

Bulk metallic glass matrix composites are advocated to be material of future owing to their superior strength, hardness and elastic strain limit. However, they possess poor toughness which makes them unusable in any structural engineering application. Inoculation has been used as an effective means to overcome this problem. Zr47.5Cu45.5Al5Co2 bulk metallic glass matrix composites (BMGMC) inoculated with ZrC have shown considerable refinement in microstructure owing to heterogeneous nucleation. Efforts have also been made to exploit modern laser-based metal additive manufacturing to fabricate BMGMC parts in one step. However, the effect of laser treatment on inoculated material is unknown. In this study, an effort has been made to apply laser based additive manufacturing on untreated and inoculated BMGMC samples. It is observed that laser treatment not only refined the microstructure but resulted in change of size, morphology and dispersion of CuZr B2 phase in base metal, heat affected zone and fusion zone. This effect is documented with back scattered electron imaging. This provides a basis for further research to quantify this phenomenon and full-scale part development.

null

['Lin, Yafu', 'Huang, Guohui', 'Huang, Yong', 'Tzeng, Jeremy', 'Chrisey, Douglas']

2021-09-29T17:38:16Z

2009-09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88198', 'http://dx.doi.org/10.26153/tsw/15139']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['Matrix-Assisted Pulsed-Laser Evaporation Direct-Write', 'laser fluence', 'cell viability']

Effect of Laser Fluence in Laser-Assisted Direct Writing of Human Colon Cell

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d6a7d316-4344-4ccf-9eff-fed82fee5862/download

University of Texas at Austin

Matrix-Assisted Pulsed-Laser Evaporation Direct-Write (MAPLE DW) has been emerging as a promising biological construct fabrication technique. The post-transfer cell viability in MAPLE DW depends on various operation conditions such as the applied laser fluence. For wide implementation of MAPLE DW-based biofabrication, the effect of laser fluence on the post-transfer cell viability should be first carefully understood. This study investigates the effect of laser fluence on the post-transfer cell viability in transferring of human colon cell HT-29. It has been observed that: 1) the HT-29 cell viability decreases from 95% to 78% as the laser fluence increases from 258 to 1,500 mJ/cm²; and 2) cell injury in this study is mainly from the process-induced mechanical stress during the cell droplet formation and cell landing processes while the effects of thermal influence and ultraviolet radiation are below the level of detection.

null

['Lee, Seungjong', 'Bureš, Martin', 'Shao, Shuai', 'Wells, Douglas N.', 'Zetek, Miroslav', 'Kepka, Miloslav', 'Shamsaei, Nima']

2023-01-25T18:14:30Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117292', 'http://dx.doi.org/10.26153/tsw/44173']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Inconel 718', 'Laser powder bed fusion', 'Laser-polishing', 'Surface roughness', 'Fatigue']

Effect of laser polishing on fatigue behavior of additively manufactured IN718

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3ec1a720-0619-4ce4-bdfc-badfbab4fdf1/download

null

This study investigates the effect of laser-polishing on the fatigue behavior of Inconel 718 fabricated using laser powder bed fusion process. Three different conditions including as-built and laser-polished using two different process parameters are considered. Uniaxial tension- compression fatigue tests are conducted in strain-controlled mode to examine the fatigue behavior for each condition. In addition, surface roughness measurements and fractography using optical microscopy and porosity measurements using the X-ray computed tomography are also performed for all conditions. The results indicate that laser-polishing alone does not improve fatigue performance, even though it can significantly reduce surface roughness. The beneficial effects of the smoother surfaces may have been countered by the volumetric defects close to the surface induced by laser-polishing. The fracture surfaces also reveal that fatigue cracks are initiated from the defects close to the surface, and therefore, fatigue behavior is not improved.

null

['Layton, Andrew C.', 'Rosen, David W.']

2019-11-20T16:41:33Z

2003

Mechanical Engineering

null

['https://hdl.handle.net/2152/78479', 'http://dx.doi.org/10.26153/tsw/5564']

null

2003 International Solid Freeform Fabrication Symposium

Open

Layer Orientation

The Effect of Layer Orientation on the Tensile Properties of Net Shape Parts Fabricated in Stereolithography

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3388b601-a3f6-4973-b2c8-fc4a3ede5454/download

null

Stereolithographic technologies create parts in thermoset plastic polymeric mixtures of acrylates and epoxies. In order to predict the mechanical behavior of these parts, it is critical to understand the effects that build parameters have on the final properties of the polymer. Using a statistics based approach, the build parameters of layer orientation, layer thickness, and resin class are used as inputs. The response variables, peak stress, elongation at break and Young’s modulus (modulus of elasticity), are examined using the methodology specified in ASTM D638- 01 with modifications as noted. An initial test in Somos 8120 showed the surprising (and statistically significant) result that load bearing capability in the build direction was greater than in the in-layer direction. Additional tensile tests in Somos 8120 and Vantico SL-5510 were undertaken to verify this result, and determine if this effect is present across different classes of resin. This report details the rationale behind this experiment, presents the results to date, and outlines future efforts.

null

['Majewski, Candice', 'Hopkinson, Neil']

2019-10-22T18:01:59Z

2002

Mechanical Engineering

null

['https://hdl.handle.net/2152/76328', 'http://dx.doi.org/10.26153/tsw/3417']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Ejection

The Effect of Layer Thickness on Ejection Forces for Injection Moulded Parts Made Using DMLS Tools

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e9c327a5-90af-402f-a78c-5c14969823f8/download

null

Direct metal laser sintered (DMLS) parts have previously been shown to be suitable for some tooling applications, in particular for injection moulding of plastics. This work shows that recent developments in materials have increased the suitability of DMLS tools for injection moulding processes, in terms of the force required to eject a part from a tool. Tools were manufactured for testing from two bronze (DirectMetal 50 and DirectMetal 20) and two steel (DirectSteel 50 and DirectSteel 20) powders, and the forces required to eject ABS parts from these tools were recorded. It can be seen that the more recent powder developments, sintered in 20 µm layers, showed a dramatic improvement over the older powders, sintered in 50 µm layers.

null

['Fitzgerald, E.', 'Everhart, W.']

2021-10-26T20:28:42Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89579

eng

2016 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', '316L', 'build location', 'tensile properties']

The Effect of Location on the Structure and Mechanical Properties of Selective Laser Melted 316L Stainless Steel

Conference paper

https://repositories.lib.utexas.edu//bitstreams/07ea44f5-1254-4dd1-9cad-33dd2c6657d6/download

University of Texas at Austin

null

['Yuksel, Anil', 'Cullinan, Michael', 'Murthy, Jayathi']

2021-10-26T19:05:48Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89559

eng

2016 International Solid Freeform Fabrication Symposium

Open

['nanotechnology', 'surface plasmon polaritons', 'near-field energy enhancement']

The Effect of Nanoparticle Clustering on Optoelectronic Property

Conference paper

https://repositories.lib.utexas.edu//bitstreams/47b18a19-33bc-4b16-9be6-3d21af6f25d2/download

University of Texas at Austin

Metal nanoparticles have been extensively investigated for the applications in micro-nano electronics, plasmonics, and chip packaging due to their enhanced thermal, mechanical and electrical properties at the nanoscale. For instance, surface-to-volume ratio and particle distribution significantly affect the sintering and melting behavior of nanoparticles relative to bulk properties. Hence, understanding the characteristic behavior of these materials is vital for the use of these nanoparticles in existing and new applications. It has been shown that at the nanoscale van der Waals forces are the dominant force between particles, which results in particle agglomeration and creates particle clustering. In this paper, we show how this nanoparticle clustering effects the optoelectronic property of the domain by applying the finite difference frequency domain method. This is the first step towards understanding the modeling of the heat transfer that characterizes the laser particle interaction for additive manufacturing using nanoparticles.

null

['Li, W.', 'Zhang, J.W.', 'Zhang, X.C.', 'Karnati, S.', 'Liou, F.']

2021-11-02T14:50:05Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89816

eng

2017 International Solid Freeform Fabrication Symposium

Open

['functionally gradient material', 'pre-mixed multi-powder', 'laser metal deposition', 'powder separation', 'composition deviation']

Effect of Optimizing Particle Size in Laser Metal Deposition with Blown Pre-Mixed Powders

Conference paper

https://repositories.lib.utexas.edu//bitstreams/78dbfdc1-b00c-4474-9dfb-b14f13fe19ff/download

University of Texas at Austin

Functionally Graded Material (FGM) is often fabricated by Laser metal deposition with pre-mixed multiple powders (PMM-powder). Since the supplied PMM-powder directly affects FGM’s composition, investigation on PMM-powder’s property is greatly needed. This paper employed experimental method to observe an important problem: PMM-powder separation in fabricating FGM. A novel particle size optimization method was introduced as solution to eliminate the powder separation. Pre-mixed pure Cu and 4047 Al powders were used to do two experiments. The first experiment result disclosed the existence of powder separation. By optimizing the particle size, the PMM-powder separation was effectively solved in the second experiment result.

null

['Gomez Bonilla, Juan S.', 'Kletcher, Robin', 'Lanyi, Franz', 'Schubert, Dirk W.', 'Bück, Andreas', 'Schmidt, Jochen', 'Peukert, Wolfgang']

2021-11-18T01:34:20Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90394', 'http://dx.doi.org/10.26153/tsw/17315']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['particle rounding', 'direct heating', 'optimized geometry', 'processability', 'polypropylene', 'selective laser sintering']

Effect of Particle Rounding on the Processability of Polypropylene Powder and the Mechanical Properties of Selective Laser Sintering Produced Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a135664f-d79c-498f-a45c-3c5b9bea1ad1/download

University of Texas at Austin

Common techniques for the production of polymer powders for selective laser sintering (SLS) involve the comminution of polymers. Comminution of polymers often results in powders made of irregular shaped particles with a low bulk density and a bad flow behavior. With the aim to improve the flowability of grinded powders and, thus, the SLS processability, a thermal process for particle shape modification was developed. This has been applied successfully for a broad variety of thermoplasts. In this contribution, a modified design of a rounding reactor with direct heating and optimized geometry is presented. The performance of the new design is assessed by the rounding of commercially available polypropylene powders. The influence of the rounding process on the packing density, flowability and particle size and shape distributions of the powders is investigated. Test specimens produced by SLS were tested to assess the effect of the rounding process on the mechanical properties of the produced parts.

null

['Subramanian, Kamatchi', 'Barlow, J.W.', 'Marcus, H.L.']

2018-11-08T14:57:06Z

1995

Mechanical Engineering

doi:10.15781/T2W37MF60

http://hdl.handle.net/2152/69880

eng

1995 International Solid Freeform Fabrication Symposium

Open

['SLS', 'copolymer', 'theoretical density']

Effect of Particle size on SLS and post-processing of Alumina with Polymer binders

Conference paper

https://repositories.lib.utexas.edu//bitstreams/be56a05b-172f-4d57-af2d-29b398985567/download

null

Alumina powders with mean particle size of 15 J.lm, 2 J.lm and 0.5 J.lm were processed by SLS using polymer binders. The 2 J.lffi and 0.5 J.lm powders were given a thermal agglomeration treatment before SLS. The green shapes after SLS were infiltrated with a colloid of aluminum oxide. After infiltration the samples were given suitable heat-treatment to remove the polymer binder by thermal decomposition followed by a sintering treatment at 16OOC. Green densities were in the range of 45% of theoretical density for the agglomerates of 2 Jlm and 0.5 J.lffi powders while it was about 36% of theoretical density for the 15 J.lffi powders. Sintered densities were about 55% of theoretical density for the samples from agglomerates of 2 J.lffi and 0.5 Jlm powders while it was 42% of theoretical density for the samples from 15 J.lm powders. The strength of samples were measured in the green state and after sintering to determine the effect of particle size.

null

['Kerninon, J.', 'Mognol, P.', 'Hascoet, J.Y.', 'Legonidec, C.']

2021-09-23T21:11:53Z

9/10/08

Mechanical Engineering

null

['https://hdl.handle.net/2152/88024', 'http://dx.doi.org/10.26153/tsw/14965']

eng

2008 International Solid Freeform Fabrication Symposium

Open

['metal deposition processing', 'CAD systems', 'CAM systems', 'welding path strategies', 'mechanical engieering']

Effect of path strategies on metallic parts manufactured by additive process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e1d2da31-dd22-48ae-b80e-5ad414a89f4b/download

null

Metal deposition processing is well known for cladding by laser or welding process. Nevertheless, these systems are not optimized for direct manufacturing. One of the main lock is the need of dedicated CAD/CAM systems to slice and generate path strategies. Research at the IRCCYN laboratory (France) focus on the impact of cladding or welding head programming on dimensional properties and microstructure of the manufactured parts. In this context, path strategies are studied and different strategies are proposed and compared. This paper presents results for welding path strategies. The integration of deposition head on a 6 axis robot system was used to improve slicing strategies and parts.

null

['Vail, N.K.', 'Barlow, J.W.']

2018-04-17T18:09:12Z

1991

Mechanical Engineering

doi:10.15781/T24X5504H

http://hdl.handle.net/2152/64337

eng

1991 International Solid Freeform Fabrication Symposium

Open

['Microencapsulation', 'Glass', 'Sintering', 'Polymer', 'Spray Drying']

Effect of Polymer Coatings as Intermediate Binders on Sintering of Ceramic Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d169afc9-b285-4ef7-b762-c7cbb69dc51b/download

null

It has been proposed that a thin polymer layer applied to the surfaces of finely divided ceramic powders would serve as a suitable intermediate binder for Selective Layer Sintering of ceramic pans. In this study, the effects of completeness and fraction of coa nd particle size distribution on sintering rates and strengths of coated ridized glass are examined. The effect of the coating as a binder during Selective Layer Sintering as well as the binder's burnout capability during post processing steps are also investigated.

null

['Wang, Z.', 'Smith, D.E.']

2021-11-03T20:50:19Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89930

eng

2017 International Solid Freeform Fabrication Symposium

Open

['nozzle flow', 'fiber orientation', 'die swell', 'carbon fiber', 'extrusion', 'fused filament fabrication']

The Effect of Polymer Melt Rheology on Predicted Die Swell and Fiber Orientation in Fused Filament Fabrication Nozzle Flow

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4262946e-0a9e-402a-89ba-4561762703e1/download

University of Texas at Austin

Short carbon fibers suspended in the polymer feedstock enhances the mechanical performance of products produced with Fused Filament Fabrication (FFF). As the melted filament is extruded and deposited on a moving platform, the velocity gradients within the polymer melt flow orientate the fibers, and the final orientation has a direct effect on the mechanical properties of printed bead. This paper numerically simulates an FFF nozzle flow, including the extrudate material beyond the nozzle exit. Finite element simulations of the extrusion process are performed with Generalized Newtonian Fluid (GNF) models and a viscoelastic rheology model, included in ANSYS Polyflow, to evaluate the polymer melt velocity field and predict die swell. Fiber orientation tensors are computed along streamlines using the Fast Exact Closure and Folgar-Tucker isotropic rotary diffusion. The predictions indicate that shear thinning behavior reduces the die swell but viscoelastic rheology significantly intensifies the extrudate swell. Orientation tensor values calculated from the flow results of the viscoelastic model yields lower principal alignment in printed beads than those computed with GNF models.

null

['Billah, Kazi Md Masum', 'Coronel, Jose Luis Jr', 'Wicker, Ryan B.', 'Espalin, David']

2021-11-09T15:44:07Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90100', 'http://dx.doi.org/10.26153/tsw/17021']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['porosity', 'electrical insulation', 'heat dissipation', '3D printed electronics', 'embedded wires', 'fused deposition modeling']

Effect of Porosity on Electrical Insulation and Heat Dissipation of Fused Deposition Modeling Parts Containing Embedded Wires

Conference paper

https://repositories.lib.utexas.edu//bitstreams/bf6b3f18-1211-4ff8-a73c-7c49dea78783/download

University of Texas at Austin

While the effects of porosity on the mechanical strength of fused deposition modeling (FDM) parts have been thoroughly investigated, there exists a need for evaluating electrical and thermal properties. This work describes the method of determining the effect of porosity that resembles 3D printed electronics. In addition to mechanical strength, determination of desirable limit of electrical insulation and heat dissipation will allow the additive manufacturing community to fabricate power electronics components with reduced cost and improved performance. For experimentation, three different sets of coupons were fabricated using Polycarbonate (PC) thermoplastic with embedded bare copper wire. Characterization included high electrical stresses and thermal testing to determine the effect of porosity on insulation and heat dissipation, respectively. During electrical characterization, higher wire density resulted in reduced breakdown strength. In thermal test, the comparisons between as fabricated and heat-treated specimen showed that heat dissipation increased by an average of 30 % to 40 %.

null

['Almangour, B.', 'Yang, J.M.']

2021-10-20T21:57:06Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89372

eng

2015 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'selective laser melting', 'porosity', 'heat treatment', 'HIP']

Effect of Post-Processing on the Microstructure and Mechanical Properties of Ultra-Low Carbon Steel Fabricated by Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/56fdcf2c-80b6-4624-848e-873413bd1367/download

University of Texas at Austin

In this study, the effects of heat treatments and hot-isotactic pressing (HIP) on the microstructure and mechanical properties of ultra-low carbon steel produced using selective laser melting (SLM) were investigated. Powder and prototypes characterizations including XRD phase analysis, microstructural observations, and hardness were performed. It was found that heat treatments at 1000 ºC and HIP process improved inter-particle bonding very slightly. Significant increases in the grain size were observed for the annealed specimens at 600ºC and above as well as after HIP due to recrystallization and further grain growth, which coincide with the drop in hardness.

null

['Poudel, Arun', 'Soltani-Tehrani, Arash', 'Shao, Shuai', 'Shamsaei, Nima']

2023-01-25T14:10:36Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117287', 'http://dx.doi.org/10.26153/tsw/44168']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Additive manufacturing', 'Powder characteristics', 'Particle size distribution', 'Volumetric defects', 'Fatigue performance']

Effect of Powder Characteristics on Fatigue Performance of Additively Manufactured 17-4 PH Stainless Steel

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f73b1f4e-0ee4-4048-802d-a8239a7cf421/download

null

The characteristics of powder feedstock used during laser powder bed fusion (L-PBF) influence the mechanical performance of the fabricated parts. The flowability, spreadability, and internal porosity of the powder can affect the porosity formation and thus, impact the fatigue performances. Two batches of 17-4 precipitation hardening stainless steel powders supplied by two different vendors were used to fabricate the L-PBF specimens and investigate the effect of powder characteristics on porosity and fatigue behavior. The powder batch with a wider particle size distribution, higher compressibility, higher cohesion between powder particles, and internal porosity resulted in a higher defect content in the fabricated specimens. Higher defect content led to inferior fatigue resistance along with more scatter in the fatigue lives. Fractography revealed the fatigue crack initiation from spherical pores as well as the lack of fusions in both batches.

null