ccm/sff-papers · Datasets at Hugging Face

['Johanson, Roy', 'Kikuchi, Noboru', 'Papalambros, Panos']

2018-10-03T16:01:19Z

1994

Mechanical Engineering

doi:10.15781/T2MG7GF2Q

http://hdl.handle.net/2152/68657

eng

1994 International Solid Freeform Fabrication Symposium

Open

['structural optimization', 'layered structures', 'generalized topology optimization']

Structural Design for Freeform Fabrication using Composite Materials

Conference paper

https://repositories.lib.utexas.edu//bitstreams/31081296-ac3a-422d-82ca-b1ed74b3694f/download

null

Advances in the development of methods to Perform topology optimization offer the ability to design novel structures composed of dense composite materials. These structures, which possess superior mechanical proPerties, can only be produced through the use of layered manufacturing techniques. In this paper, we demonstrate a technique for the design of layered structures composed of composite materials. In addition, this procedure allows the design of the composite materials used for fabrication of such components on a microstructural level.

null

['Smith, Tyler', 'Failla, Jordan', 'Lindahl, John', 'Kim, Seokpum', 'Hassen, Ahmed Arabi', 'Duty, Chad', 'Joshi, Pooran', 'Stevens, Christopher', 'Kunc, Vlastimil']

2021-11-15T22:26:06Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90294', 'http://dx.doi.org/10.26153/tsw/17215']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['printing monitoring', 'internal failures', '3D printed structures', 'health monitoring', '3D printing']

Structural Health Monitoring of 3D Printed Structures

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d02d2e1f-a82f-4c5e-a7e5-92ae59a5d7bf/download

University of Texas at Austin

3D printed parts are used in industry for both tooling application and smaller parts in assembled structures. Articles made through polymer based additive manufacturing are anisotropic and may have defects throughout the part. For instance, the layer to layer interactions are weaker than the in-plane printing which can cause delamination of the layers. Identifying when and where the cracks form can be very difficult if the cracks are inside the structure This paper introduces an innovative patent-pending method to monitor polymer-based 3D printed structures for internal failures by printing a highly sensitive conductive material into the part itself. When a section of the conductive material inside the part is damaged or split, the resistance across the conductive pathway increases which will indicate that the article has been damaged. We present several small printed circuits and observations that show as a crack is introduced to the structure, the resistance measured increases which alerts users that a crack has formed/propagated.

null

['Siggard, Erik J.', 'Madhusoodanan, Anand S.', 'Stucker, Brent', 'Eames, Brandon']

2020-02-27T19:46:52Z

2006

Mechanical Engineering

null

['https://hdl.handle.net/2152/80097', 'http://dx.doi.org/10.26153/tsw/7118']

eng

2006 International Solid Freeform Fabrication Symposium

Open

Ultrasonic Consolidation

Structurally Embedded Electrical Systems Using Ultrasonic Consolidation (UC)

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ec7e9d21-e42f-4d4b-ab09-2befb45d60f8/download

null

Current research has demonstrated the use of Ultrasonic Consolidation (UC) to embed several USB-based sensors into aluminum, and is working toward embedding suites of sensors, heaters and other devices, connected via USB hubs, which can be monitored and controlled using an embedded USB capable processor. Additionally, the research has shown that electronics can be embedded at room temperature, but with some inter-layer delamination between the ultrasonically bonded aluminum layers. Embedding sensors and electronics at 300o F to overcome the delamination issues resulted in optimal bonding, and the sensors used thus far have functioned normally. Future investigation will explore other UC parameter combinations to ascertain the quality of embedding at lower temperatures.

null

['Khurana, Jivtesh B.', 'Simpson, Timothy W.', 'Frecker, Mary']

2021-11-16T15:26:51Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90313', 'http://dx.doi.org/10.26153/tsw/17234']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['active-z printing', 'layer generation', '3D layers', 'material extrusion additive manufacturing']

Structurally Intelligent 3D Layer Generation for Active-Z Printing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1c2ac32e-86be-4477-bdef-dc496a3fa5e9/download

University of Texas at Austin

Active-Z Printing offers the ability to deposit material along non-planar layers to control the mechanical behavior of parts produced by material extrusion additive manufacturing. These non-planar layers can be exploited to incorporate a part’s loading conditions into the slicing process by aligning deposited layers with predicted localized stress tensors. In this work, we demonstrate that superior structural performance can be achieved by taking advantage of layer shapes derived from principal stress trajectories. A slicing method incorporating stress field data is developed to generate 3D layers from principal stress trajectories. As a demonstration, a 3-point bend specimen is manufactured with 3D layers derived from principal stress trajectories developed in a deformed specimen. Mechanical tests are conducted and 3-point bend specimens are shown to have superior mechanical response. This novel approach introduces new capabilities to Additive Manufacturing for structurally intelligent fabrication.

null

['Jayanthi, Suresh', 'Keefe, Michael', 'Gargiulo, Edward P.']

2018-10-03T15:44:22Z

1994

Mechanical Engineering

doi:10.15781/T2862BW9H

http://hdl.handle.net/2152/68652

eng

1994 International Solid Freeform Fabrication Symposium

Open

['stereolithography', 'photopolymer models', 'laser scanning']

Studies in Stereolithography : Influence of Process Parameters on Curl Distortion in Photopolymer Models

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a274c618-617c-4c2f-9b97-d89361e4c269/download

null

To make the stereolithography process more useful in the manufacturing industry, the dimensional accuracy of the parts it creates should be very high. But due to the nature of the polymerization process and the mechanism of laser scanning, distortions are induced in the parts. Curl distortion is a major source of inaccuracy in this photopolymer based technology. This paper approaches the problem from a process related point of view by addressing the major parameters reponsible for curl.The work presented here is a continuation of a similar work presented at the SFF symposium in 1993 [1].

null

['Wang, Jiwen', 'Li, Xiaoxuan', 'Shaw, Leon L.', 'Marcus, Harris L.', 'Cameron, T.B.', 'Kennedy, C.']

2019-10-22T18:05:31Z

2002

Mechanical Engineering

null

['https://hdl.handle.net/2152/76329', 'http://dx.doi.org/10.26153/tsw/3418']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Restoration

Studies on Slurry Extrusion for Dental Restoration

Conference paper

https://repositories.lib.utexas.edu//bitstreams/bc0fdedd-02dd-451a-bb19-e40d78d34300/download

null

This study investigates dental restoration via dental powder delivery by slurry extrusion, followed by laser densification of these extruded slurries. The entire process is fully controlled by a computer. The shape of the extrudate before laser densification depends strongly on the formulation of slurries. Slurries prepared in a stable pH range can disperse high volume of solids, but have low viscosities and spread uncontrollably when extruded. In contrast, slurries first prepared in a stable pH range and subsequently adjusted to an unstable pH range have exhibited pseudoplastic behavior. Such slurries have a low extrusion pressure to avoid phase separation, and at the same time their yield points are high enough to maintain the shape of extrudates.

The authors gratefully acknowledge financial support provided by the National Science Foundation under Grant No: DMI-9908249.

null

['Belchou, Alexander P.', 'Jacob, Ashish', 'Joshi, Sanjay', 'Reutzel, E.W.', 'Coutts, Peter']

2023-02-10T13:56:06Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117447', 'http://dx.doi.org/10.26153/tsw/44328']

eng

2022 International Solid Freeform Fabrication Symposium

Open

SS316L

Studies on Thin and Thick-Walled SS316L Overhanging Specimens Manufactured Using Powder-Fed Laser-Based Directed Energy

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7d3722f1-5109-4f2c-8f48-0a1be4ac4f40/download

null

Effective Design for Additive Manufacturing (DfAM) requires accurate knowledge of a machine’s capabilities and limitations. One important factor is the machine’s ability to deposit unsupported overhanging features. A general method was devised to characterize the ability of a powder-fed Laser-Based Directed Energy Deposition (LB-DED) system to deposit overhanging features with various overhang angles, wall thicknesses, and scan strategies, which was then investigated on a DMG Mori LASERTEC 65 3D Hybrid LB-DED system using 3-axis toolpaths. To assess the accuracy of the manufactured overhang angle, for each specimen the angle of the downward facing surface and upward facing surface were measured and compared to the target overhang angle. It was observed that for the longitudinal scan strategy, overhang accuracy substantially degraded as wall thickness increased. For the transverse and cross hatch patterns there is no observable trend between the achievable overhang angle and the wall thickness. In addition, it was observed that in general increasing the target overhang angle degrades the accuracy of the manufactured overhang angle. The most accurate overhang angles overall were achieved for the longitudinal 1 bead thick specimens. These results will help inform future DfAM and path planning strategies. This research fills a gap in the literature by providing a general method to assess overhang capabilities for LB-DED systems.

null

Yang, L.

2021-11-01T21:39:42Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89763

eng

2016 International Solid Freeform Fabrication Symposium

Open

['cellular structures', 'size effects', 'simulation']

A Study About Size Effects of 3D Periodic Cellular Structures

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0975d2db-2b49-4ad3-a738-48fe6d08885e/download

University of Texas at Austin

In the design of unit cell based cellular structures, idealized boundary conditions are often assumed to simplify analysis. However, such treatments also result in various deviations from reality. In this study, both lateral and along-the-stress size effects s of multiple cellular structural designs under compressive stress with constrained boundary motion were investigated using simulations. It was found that different unit cell designs exhibit significantly different size effects, which might be affected by the unit cell dimensional aspect ratio, the unit cell Poisson’s ratios and the unit cell orientations. This study provides a glimpse into the design considerations associated with such phenomenon.

null

['Philo, A.M.', 'Sutcliffe, C.J.', 'Sillars, S.', 'Sienz, J.', 'Brown, S.G.R.', 'Lavery, N.P.']

2021-11-03T21:33:54Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89938

eng

2017 International Solid Freeform Fabrication Symposium

Open

['gas flow', 'inlet design', 'Renishaw AM250', 'metal powder bed fusion', 'laser powder bed fusion', 'Hot Wire Anemometer']

A Study into the Effects of Gas Flow Inlet Design of the Renishaw AM250 Laser Powder Bed Fusion Machine Using Computational Modeling

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4902de0a-0beb-44ad-bcf1-8f19a99ab085/download

University of Texas at Austin

Previous work has highlighted the importance of the gas flow system in laser powder bed fusion (L-PBF) processes. Inhomogeneous gas flow experienced at the surface of the powder bed can cause variations in mechanical properties over a build platform, where insufficient removal of by-products which cause laser attenuation and redisposition of byproducts are believed to contribute to these variations. The current study analyses the gas flow experienced over a build platform in a Renishaw AM250 metal powder bed fusion machine via Hot Wire Anemometer (HWA) testing. Velocity profiles of the flow directly above the powderbed and through the centre plane normal to the inlets have been categorized. These HWA results illustrate the inhomogeneity of the gas flow experienced over the build platform and from literature imply that there will be insufficient removal of by-products and hence variable build quality in specific areas of the build platform. A Computational Fluid Dynamics (CFD) model was created in ANSYS Fluent and validated against HWA results coupled with a Discrete Phase Model (DPM) representing the expulsion of spatter. Velocity contours of simulated against experimental are compared, where the results appear in good agreement. The multiphase CFD model was then used to explore the effects of changing inlet design parameters using a Design of Experiments (DOE) study based on an Optimal Space Filling (OSF) method. This was to understand the effect of design parameters on flow uniformity, local gas velocity over the processing area and spatter particulate accumulation within the build chamber. The initial design study found that flow uniformity could potentially be increased by 21.05% and spatter accumulation on the processing area could be reduced by 26.64%. In addition, this has given insight into important design considerations for future generation of LPBF machines.

null

['Liu, Qingbin', 'Leu, Ming C.']

2020-02-17T14:47:22Z

2004

Mechanical Engineering

null

['https://hdl.handle.net/2152/80000', 'http://dx.doi.org/10.26153/tsw/7025']

eng

2004 International Solid Freeform Fabrication Symposium

Open

Freeze Cast Process

Study of Ceramic Slurries for Investment Casting with Ice Patterns

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0ec7d73b-5c84-4fbd-97f8-140f3a65bdcc/download

null

Ice patterns generated by rapid freeze prototyping or a molding process can be used to make ceramic investment molds for metal castings. Due to the use of ice, the ceramic slurries must be poured around the pattern and cured at sub-freezing temperatures. Success of this process depends greatly on the mold strength after the gelation of the slurries. This paper describes the experimental results of the mold strength after the gelation of the slurries under different compositions. The parameters considered include mixing time, alumino-silicate vs. fused silica ratio, volume of binder, and volume of catalyst. The strength of the gelled slurries is examined by breaking test bars on a four-point bending apparatus. Weibull modulus for each trial is calculated based on the breaking strength from four-point bend tests. Analysis of variance for breaking strength and Weibull analysis is performed to evaluate the significance of the effect of each parameter. The casting of a bolt is used to demonstrate that metal castings of complex geometry can be fabricated using investment casting with ice patterns.

null

['Medrano, V.A.', 'Caballero, K.', 'Arrieta, E.', 'Benedict, M.', 'Wicker, R. B.', 'Medina, F.']

2023-03-29T16:37:25Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117684', 'http://dx.doi.org/10.26153/tsw/44563']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Additive manufacturing', 'LPBF', 'F357', 'aging', 'aluminum']

Study of Different Aging Conditions for Analysis of Microstructure and Mechanical Properties of F357 Alloy Fabricated in LPBF Printer

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5fcd7317-5ef7-4781-9d5a-91e72fb4f484/download

null

Aluminum F357 is a widely used material for casting in aerospace and additive manufacturing industry. Heat treatments are commonly applied to some aluminum alloys to modify its properties. With a further study on the aging and performance of the F357 with 3D printing technology, several industries benefit of this, military, automotive and aerospace are some examples, because the numerous components casted in service. This work presents mechanical properties of F357 specimens fabricated with EOS technology and subjected to heat treatments. Heat treatments conditions were applied to tensile specimens and tested. Furthermore, the specimens were subjected to artificial thermal aging for 100 h and 1000 h at two different temperatures (285 ºF and 350 ºF), and their mechanical properties were also determined. Finally, remarks on the comparison between the heat treatments and the effect of thermal aging on the microstructures and mechanical properties of the specimens will be presented.

null

['Hopkinson, Neil', 'Dickens, Phil']

2019-02-19T16:57:06Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73430', 'http://dx.doi.org/10.26153/tsw/582']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['CAD', 'SL process']

Study of Ejection Forces In The AIM™ Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7716edb8-1b01-4fe9-b5c7-38edbb680193/download

null

The AIM™processhas been used to successfully produce short runs ofinjection moulded parts. One ofthe main drawbacks ofthe process is the tendency ofthe tools to be damaged during part ejection1 . At De Montfort University a successful AIMTM moulding cycle has been developed in which simple shapes from polypropylene are produced and the ejection forces required are measured. TWQ different ejection methods are used; one uses conventional ejector pins andthe other uses a conformal ejector pad. The tool surface roughness is measured before and after moulding to observe any changes caused by ejection. Results show that ejector pins require a lower ejection forcethan a conformal ejector pad and this may contribute to longer tool life forthe AIM™process. Possible reasonsfor the results are discussed along with recommendations for further work.

null

['Dutson, Alan J.', 'Wood, Kristin L.', 'Beaman, Joseph J.', 'Crawford, Richard H.', 'Bourell, Daniel L.']

2019-10-18T15:06:30Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76232', 'http://dx.doi.org/10.26153/tsw/3321']

eng

2001 International Solid Freeform Fabrication Symposium

Open

SFF Parts

A Study of Functional Testing with SFF Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4e03b62c-4fd4-4a4e-8263-3c27d0cba025/download

null

A study of functional testing with SFF parts is presented. The study includes the use of traditional similitude methods as well as advanced similitude methods for predicting product performance through prototype testing. Cantilever beams created from the selective laser sintering process are used to predict the static deflection of both aluminum and polycarbonate beams. The results of 20 experiments using various geometric, loading, and material configurations are presented. Results of the study suggest that a coupling between geometry and material properties exists in SLS parts. Possible sources for the coupling are discussed. An approach for establishing the functional relationship between material and geometry is outlined.

null

['Baich, Liseli', 'Manogharan, Guha']

2021-10-19T18:44:27Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89321

eng

2014 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'material extrusion', 'fused deposition modeling', 'mechanical strength', 'infill print parameters and cost analysis']

Study of Infill Print Parameters on Mechanical Strength and Production Cost-Time of 3D Printed ABS Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/adddca87-4b50-4e42-b985-1733e84b7958/download

University of Texas at Austin

The ever-growing adoption of Additive Manufacturing (AM) can be attributed to lowering prices of entry-level extrusion-based 3D Printers. It has enabled using AM for mainstream DIY, STEM education, prototypes and often, to produce custom complex commercial products. With the growing number of available printers and newer materials, the influence of print parameters specifically infill patterns on the mechanical strength and print costs need to be investigated. This study presents the correlation of infill pattern selection and several mechanical properties along with final part cost and production time. Infill with varying design parameters are analyzed with respect to mechanical properties determined using ASTM standards, fabrication cost and time. Relevant applications are presented for all the varied infill designs. Findings from this study will help formulate criteria for relevant economically sound infill design pattern for real world applications.

null

['Chiu, Y.Y.', 'Liao, Y.S.', 'Hou, C.C.']

2019-10-24T18:35:33Z

2002

Mechanical Engineering

null

['https://hdl.handle.net/2152/77424', 'http://dx.doi.org/10.26153/tsw/4513']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Object Manufacturing

The Study of On-Line Waste Material Removal Procedures for Bridge Laminated Object Manufacturing (LOM) Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4a9f839f-7a54-4063-b995-8852726d0f19/download

null

Focusing on the drawbacks inhered in the laminated object manufacturing (LOM), a new Bridge-LOM process and its associated building algorithm are proposed in this paper. The proposed Bridge-LOM process starts with the construction of the bridge structures to link a stack of 2-D geometry contours to the outer frame based on the proposed bridge building algorithm. Afterwards, laser is directed to cut along the contours, and then the upper pressing head is pushed down and the layers are bonded. This is followed by spraying some adhesive on the top of bonded layers. The procedures of cutting, bonding and adhesive spraying are repeated until the complete 3D part is produced. From the experiments, it is verified that the proposed Bridge-LOM process not only saves laser-cutting time, the time on waste material removal is also reduced significantly by more than 80%. Furthermore, the hollow bottle can even be fabricated.

null

['Shrestha, Subin', 'Starr, Thomas', 'Chou, Kevin']

2021-11-18T00:24:01Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90369', 'http://dx.doi.org/10.26153/tsw/17290']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['computed tomography', 'porosity', 'selective laser melting']

A Study of Pore Formation During Single Layer and Multiple Layer Build by Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d254c557-d98c-4a15-8361-bd6747698a6d/download

University of Texas at Austin

n this study, different hatch spacings were used to fabricate single layer and multiple layers, and its effect on porosity was investigated by using microcomputed tomography. The combination of laser power (100 W, 150 W, 175 W, and 195W) and scan speeds (600 mm/s, 800 mm/s, 1000 mm/s and 1200 mm/s) which resulted in the least number of pores were selected from the previous single-track experiment. Six levels of hatch spacings were selected based on the track width to form single and multiple layers: 60%, 70%, 80%, 90%, 120% and 150% of track widths. For the multilayer build, the variation in keyhole porosity within the given window of parameters were found to be attributed to the variation in the hatch spacing. In general, the pore number decreased with increase in hatch spacing from 60% to 90% but increased when hatch spacing further increased from 90% to 120%.

null

['Ruprecht, John', 'Agarwal, Kuldeep']

2021-12-06T21:34:25Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90679', 'http://dx.doi.org/10.26153/tsw/17598']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['printing parameters', 'biocomposites', 'cobalt chrome', 'tricalcium phosphate', 'binder jetting based additive manufacturinng']

Study of Printing Parameters in Binder Jet Additive Manufacturing of Cobalt Chrome - Tricalcium Phosphate Biocomposite

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e801e5e0-3a5e-4def-b552-1c6e04f6188a/download

University of Texas at Austin

Traditional metals such as stainless steel, titanium and cobalt chrome are used in biomedical applications (implants, scaffolds etc.) but suffer from issues such as osseointegration and compatibility with existing bone. One way to improve traditional biomaterials is to incorporate ceramics with these metals so that their mechanical properties can be similar to cortical bones. Tricalcium phosphate is such a ceramic with properties so that it can be used in human body. This research explores the use of binder jetting based additive manufacturing process to create a novel biocomposite made of cobalt chrome and tricalcium phosphate. Experiments were conducted and processing parameters were varied to study their effect on the printing of this biocomposite. Layer thickness, binder saturation and drying time affected the surface finish, dimensional tolerance and the density of the green samples. This effect is important to understand so that the material can be optimized for use in specific applications.

null

['Chivate, Aditya', 'Guo, Zipeng', 'Zhou, Chi']

2023-01-20T13:58:20Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117254', 'http://dx.doi.org/10.26153/tsw/44135']

spa

2022 International Solid Freeform Fabrication Symposium

Open

['Proximity effects', 'oxygen inhibition', 'cross-talk', 'stereolithography']

Study of Proximity Effect in Projection-Based Micro Stereolithography Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/21b140b7-2bf3-43e0-bf6b-eaefbe99aecf/download

null

Micro Projection-based stereolithography (PSL) is a powerful technique that has the potential to disrupt microfabrication. However, a significant challenge that plagues µPSL is the local change in thresholds depending on the pitch between adjacent features, and having features in close spatial proximity generates undesired artifacts. This is termed as "proximity effect," which strongly limits the attainable fabrication resolution. This can be linked to pixel-pixel light interactions and is found to affect the process in spatial as well as temporal domains. Despite tormenting researchers for a long, not much has been done to study these effects in DLP printing. Models developed for laser-based systems can be used to explain the proximity effect in µPSL. However, they still rely on hindsight observations, fail to consider the effects of large area projection, and fail to explain how the local change in thresholds affects the part size. This research uses in-situ observation systems to study the spatial and temporal proximity effects in single-shot PSL microfabrication. We briefly illustrate the role of oxygen in the proximity effect and lay the foundations to better understand the proximity effect in periodic structures with micronic inter- feature distances.

null

['Thomas, Baily', 'Sutton, Austin', 'Leu, Ming C.']

2021-11-02T15:06:56Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89822

eng

2017 International Solid Freeform Fabrication Symposium

Open

['304L', 'stainless steel', 'cast iron', 'bonding', 'selective laser melting']

Study of Selective Laser Melting for Bonding of 304L Stainless Steel to Grey Cast Iron

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7b04a9a7-5162-4c71-b24b-c5135cf0700f/download

University of Texas at Austin

While cast iron is widely used in industry, a major limitation is the weldability of a dissimilar material onto cast iron due to hot cracking as a result of lack of ductility from graphite flakes. Consequently, a significant amount of preheat is often employed to reduce the cooling rate in the fusion zone, which, however, may lead to distortion of the welded parts. A potential remedy could be the Selective Laser Melting (SLM) process, where only small melt pools are created and thus the overall energy input is reduced. The present paper describes an investigation of the SLM process to join 304L stainless steel with cast iron. In this study, 304L stainless steel particles ranging from 15-45 μm in size were melted on a grey cast iron substrate by the SLM process. Multiple sets of parameter values were chosen to test different energy densities on the tensile strength of the bond created. Subsequent characterization of the bonded area included energy dispersive spectroscopy (EDS) mapping for obtaining insight into the elemental diffusion, and metallography for visualization of the microstructure. A range of energy densities was identified for purposes of eliminating bond delamination and maximizing mechanical strength.

null

['Ganesh-Ram, A.', 'Hanumantha, M.', 'Ravichander, B.B.', 'Farhang, B.', 'Ramachandra, S.', 'Shayesteh Moghaddam, N.', 'Amerinatanzi, A.']

2021-12-06T23:15:23Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90712', 'http://dx.doi.org/10.26153/tsw/17631']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['laser powder bed fusion', 'Ti-6Al-4V', 'spattering', 'anti-spatter liquid']

Study of Spatter Formation and Effect of Anti-Spatter Liquid in Laser Powder Bed Fusion Processed Ti-6Al-4V Samples

Conference paper

https://repositories.lib.utexas.edu//bitstreams/bf60ffac-beb6-4607-9bf4-ed4077ecb323/download

University of Texas at Austin

Spatter deposition has been found to have serious effects on mechanical properties of the metal parts printed using laser powder bed fusion technique. The spatter powder formation can cause unfavorable changes in phases and impurity content and may result in the formation of defects in the as-fabricated parts. This study is the first of its kind focusing on mitigation of spatter formation through a novel technique of spraying nonflammable welding liquid during the LPBF process. Identifying the spatter particle size distribution and dampening its formation have been the focus of this study. Characterization of the powder spatter behaviors for Ti-6Al-4V have been made through image processing and microstructure characterization. The findings of this study will help in improving the mechanical properties and reducing the post-processing procedures required for the parts processed by LPBF. This study is believed to bring a new perspective in production planning and print quality optimization to obtain an enhanced performance from laser powder bed fusion technique.

null

['Zhang, Chunbo', 'Li, Leijun']

2020-03-05T18:36:35Z

9/14/06

Mechanical Engineering

null

['https://hdl.handle.net/2152/80140', 'http://dx.doi.org/10.26153/tsw/7161']

eng

2006 International Solid Freeform Fabrication Symposium

Open

Ultrasonic consolidation

A Study of Static and Dynamic Mechanical Behavior of the Substrate in Ultrasonic Consolidation

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7053a21e-6289-4af9-91af-d8e19577ca11/download

null

A new 2-D FEM model is developed for a fundamental study of the time dependent mechanical behavior of the substrate in ultrasonic consolidation. The simulation shows that for a given vibration condition, the amplitude of contact friction stress and displacement stabilize to a saturated state after certain number of ultrasonic cycles. With the increased substrate height, the amplitude of contact frictional stress decreases, while that of contact interface displacement increases. The energy density and transfer coefficient at the contact interface with different substrate heights can be used as parameters to predict the potential for ultrasonic bonding. The reason for the decrease in the frictional stress and displacement at the contact interface for certain substrate height seems to be caused by the complicated wave interference occurring in the substrate. A specific substrate geometry generates a minimum strain state at the interface as a result of wave superposition. Such minimum strain state is believed to have produced the “lack of bonding” defect.

null

['Dibua, Obehi G', 'Liao, Aaron', 'Tasnim, Farzana', 'Grose, Joshua', 'Behera, Dipankar', 'Foong, Chee S', 'Cullinan, Michael']

2023-01-23T14:05:41Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117279', 'http://dx.doi.org/10.26153/tsw/44160']

eng

2022 International Solid Freeform Fabrication Symposium

Open

nanoparticles

A Study of the Electrical Resistivity of Sintered Copper Nanoparticles

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f2415027-d636-4baa-a7c6-5c93a3465a1e/download

null

Microscale Selective Laser Sintering is a novel Additive Manufacturing process being built to fabricate parts with microscale resolution for applications in the microelectronics industry where small feature sizes are critical. This process works by sintering nanoparticles to give a better control on feature sizes. To get an idea of the mechanical strength of the parts fabricated with this process, it is important to be able to quantify the density in the manufactured parts. However, the parts fabricated with this process are too thin to physically handle enough to measure the density, but it is possible to measure the electrical resistance of these parts. So, in order to get the density of these parts, the relationship between electrical resistance and density has to be known. As such this paper presents an experimental study done on sintered copper nanoparticles to relate density to electrical resistance.

null

['Liao, Y.S.', 'Li, H.C.', 'Chiu, Y.Y.']

2019-10-30T16:41:58Z

2002

Mechanical Engineering

null

['https://hdl.handle.net/2152/78190', 'http://dx.doi.org/10.26153/tsw/5279']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Object Manufacturing

Study of the Heating-and-Pressing Separation Process of Laminated Object Manufacturing (LOM)

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f28d5073-a694-4afc-bc27-c023045af08f/download

null

To improve hot-pressing process currently employed by the laminated object manufacturing (LOM), an innovated heating-and-pressing separation system is proposed, and heat transfer problems of this system is investigated. A thermal model is first established. It is solved numerically by the finite element method (FEM) software ANSYS, and verified by experiments. According to the numerical solution under various operating conditions, it is suggested that if the temperature and the moving speed of the heater are both increased, the depth of the heat affected laminates will be reduced. The processing time will be shortened and the manufacture efficiency will be promoted. Through analysis, it is concluded that, to obtain finished parts of high quality, the appropriate distance between the roller and the heater can be determined.

null

['Vrancken, B.', 'Wauthle, R.', 'Kruth, J.-P.', 'Van Humbeeck, J.']

2021-10-11T20:17:53Z

8/16/13

Mechanical Engineering

null

['https://hdl.handle.net/2152/88625', 'http://dx.doi.org/10.26153/tsw/15559']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', 'residual stress', 'material properties', 'microcracking', 'surface oxidation', 'ansiotropy']

Study of the Influence of Material Properties on Residual Stress in Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8b6307f8-ce47-42b8-a38c-46c5d1e055cb/download

University of Texas at Austin

Selective laser melting (SLM) is characterized by highly localized heat input and short interaction times, which lead to large thermal gradients. In this research, nine different materials are processed via SLM and compared. The resulting microstructures are characterized by optical and scanning electron microscopy. Residual stresses are measured qualitatively using a novel deflection method and quantitatively using X-ray diffraction. Microcracking, surface oxidation and the anisotropy of the residual stress are discussed. The different phenomena interacting with the buildup of residual stress make it difficult to distinguish the possible correlations between material parameters and the magnitude of residual stresses.

null

['Cunico, Marlon Wesley Machado', 'Cunico, Miriam Machado', 'de Carvalho, Jonas']

2021-10-21T21:10:33Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89450

eng

2015 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'smoothing process', 'dimensional evaluation']

Study of Vapourised Solvent Attack on Additive Manufacturing Part Surface

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b0e4efcc-506d-4e32-964c-cc62520bf4e7/download

University of Texas at Austin

The additive manufacturing technologies has been facing an extraordinary growth during that last years, mainly as consequence of the increase of low cost FDM technologies into the marketing. In contrast with that, one of the main disadvantages of this sort of equipment is the final object finishing. For that reason, the main goal of this work is to present and characterise the post-processing which was introduced in the marketing as smoothing. In addition, a concise overview about the theory beneath this process is presented besides an experimental study that evaluates the impact of this process for the main mechanical properties of object.

null

['Mookerjee, Adaleena', 'Cohen, Daniel L.', 'Peng, David H.', 'Bonassar, Lawrence J.', 'Lipson, Hod']

2021-09-29T17:23:28Z

9/18/09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88193', 'http://dx.doi.org/10.26153/tsw/15134']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['variable-stiffness hydrogels', 'alginate printing', 'cell-seeded implants', 'surgical training', 'surgical planning', 'synthetic surgical models']

A Study of Variable Stiffness Alginate Printing for Medical Applications

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e9e32a31-02ee-4935-849e-34dc7d6a86c2/download

University of Texas at Austin

Technologies for multi-material 3D-printing of anatomical shapes are useful both for fabrication of heterogeneous cell-seeded implants as well as for fabrication of synthetic models for surgical planning and training. For both these applications, it would be desirable to print directly with biological materials to best emulate the target’s properties. Using a novel material platform, we describe a series of experiments attempting to print variable-stiffness hydrogels. We vary compliances by alternating 2% alginate hydrogel and a Dextran-infused calcium chloride post-crosslinker. Stiffness throughout the construct ranged from 4 kPa to 20 kPa as a function of post-crosslinker concentration, which was spatially specified by the user.

null

['Bryant, Frances D.', 'Sui, Guanghua', 'Leu, Ming C.']

2019-10-30T16:59:07Z

2002

Mechanical Engineering

null

['https://hdl.handle.net/2152/78194', 'http://dx.doi.org/10.26153/tsw/5283']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Rapid Freeze Prototyping

A Study on Effects of Process Parameters in Rapid Freeze Prototyping

Conference paper

https://repositories.lib.utexas.edu//bitstreams/eedbea5e-2c92-41f4-81b0-17363c0763ce/download

null

Rapid Freeze Prototyping (RFP) is a relatively new solid freeform fabrication process, which builds a three-dimensional part according to a CAD model by depositing and freezing water droplets layer by layer. A study on the effects of RFP process parameters including the nozzle scanning speed, droplet size, and droplet frequency in building ice parts with a single-nozzle work head is made. Presented in this paper are the results of this study which indicate that these process parameters determine the ice layer thickness and ice line width, which in turn determine the surface roughness and the waiting time required after depositing each layer of water (i.e. between successive layers) during the ice part building process.

This project is supported by a National Science Foundation Grant (DMI-0128313) and a Department of Education GAANN Fellowship Grant (P200A010446).

null

['Bryant, Frances D.', 'Leu, Ming C.']

2020-02-14T15:19:42Z

2004

Mechanical Engineering

null

['https://hdl.handle.net/2152/79983', 'http://dx.doi.org/10.26153/tsw/7008']

eng

2004 International Solid Freeform Fabrication Symposium

Open

Rapid Freeze Prototyping

Study on Incorporating Support Material in Rapid Freeze Prototyping

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9a2cc7d6-8697-402a-bd1d-1be803ef2f1e/download

null

Rapid Freeze Prototyping (RFP) is a rapid prototyping method that uses water freezing into ice to make three-dimensional parts. Each layer of a geometry is deposited and allowed to freeze before the next layer is added. Using a support material in RFP is a relatively new addition to the process. Validating the successful use of a support material in conjunction with the main build material of water is presented in this paper. The support material selected for use is a eutectic sugar solution. The selection criteria, properties, and characteristics of the support material are discussed. Of particular interest is the diffusion between the support and main build material, which must be minimized to an acceptable level for producing good quality, reproducible, complex parts.

null

['Nouri, Hadis', 'Khoshnevis, Behrokh']

2021-10-21T14:58:38Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89386

eng

2015 International Solid Freeform Fabrication Symposium

Open

['selective inhibition sintering', 'inhibitor', 'polyamide']

Study on Inhibition Mechanism of Polymer Parts in Selective Inhibition Sintering Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9c376a64-dc63-44a0-84ed-fad55859efae/download

University of Texas at Austin

The selective inhibition sintering (SIS) process is an additive manufacturing technique that builds parts based on powder sintering. In this process parts are made upon deposition of a solution, called inhibitor, at the boundary profile. The inhibitor prevents polymer particles to coalescence under heat exposure on each layer. The inhibited boundary profile acts as a sacrificial mold that can be easily removed, leaving a chemically pure part. One of the influential factors in fabrication resolution by SIS is the proper selection of an inhibitor. The best inhibition mechanism results in ease of separation of the part from undesired regions while maintaining part accuracy. In this paper, we investigate a framework for selecting an appropriate inhibitor for the process. Different experiments have been performed and inhibition theory has been studied on polyamide (PA) samples. Specifically, as an alternative to exhaustive experiments on solutions and polymers, a hybrid method based on crystallization is proposed to characterize the effectiveness of the inhibitor. Differential Scanning Calorimetry (DSC) tests are used to study changes in thermal properties of the samples. It is found that the sintering period increases as crystallinity of the polymer decreases. Results show that polymer samples exposed to sodium hypochlorite solution has longer sintering periods. Design of experiments has been used to study shrinkage behavior of polymer samples through bulk sintering.

null

['Zhang, Haiou', 'Rui, Daoman', 'Xie, Yang', 'Wang, Guilan']

2021-10-07T17:34:30Z

8/16/13

Mechanical Engineering

null

['https://hdl.handle.net/2152/88490', 'http://dx.doi.org/10.26153/tsw/15424']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['metal additive manufacturing', 'metamorphic rolling mechanism', 'metamorphic rolling', 'surface deposition']

Study on Metamorphic Rolling Mechanism for Metal Hybrid Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/21ee0d1d-859d-4e6d-8c4b-b0aa19ff0cb7/download

University of Texas at Austin

The uneven of the surface shaped by overlapping beads has been observed during metal additive manufacturing (AM). These uneven surfaces have a cumulative effect on the accuracy of the component in the Z-direction. Conventionally, each layer was face milled to solve the problem, which resulted in material and time wastes. In this paper, the metamorphic mechanism was introduced to metal additive manufacturing and a novel metamorphic rolling mechanism with three rollers was developed. It configuration can change according to the feature of the part to rolling the deposition upper or lateral surfaces. The influence of rolling force and rolling temperature on the shape of bead was studied. Optimal rolling parameters were obtained to control the height and width of overlapping beads. In addition, it is worthwhile to mention that the hybrid deposition and rolling method will be beneficial to refine grain, avoid the hot crack and improve the mechanical properties of parts.

null

['Gibson, F.P.Y. Ting I', 'Cheung, W.L.']

2019-09-25T15:59:22Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76000', 'http://dx.doi.org/10.26153/tsw/3099']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Conductive

Study on selective laser sintering components with electrically conductive channels

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a049e937-de4b-4a1b-b04d-2ff70816b0c9/download

null

Electrically conductive channe ls were created using conductive carbon cement (CCC) by a simple non-contact continuous deposition method on sintered DuraFormTM Polyamide parts. The deposition system consisted of a drive circuit, a Micro Inert Solenoid Valve (MIV), a nozzle head and two liquid material reservoirs. Effect of CCC/solvent ratio, speed of deposition head and sintering condition of the Polyamide base material on the electrical properties of the conductive channels were investigated. The paper will then go on to discuss how these results relate to potential applications of Selective Laser Sintering (SLS) components with electrical property.

null

Hu, Jing

2021-11-02T20:29:01Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89888

eng

2017 International Solid Freeform Fabrication Symposium

Open

['3D printing', 'STL', 'cutting plane', 'slicing thickness', 'contour', 'uniform', 'adaptive']

Study on STL-Based Slicing Process for 3D Printing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ccec79d1-ad88-4ef4-b7fb-2fbf7809db17/download

University of Texas at Austin

This paper presents a framework about layer contour reconstruction algorithms by STL-based slicing process for 3D printing. The experimental results by the traditional uniform slicing show the contour outline of each layer and comparison among the different slicing thickness of the cutting z-plane. We then proposed a simple but effective adaptive slicing method to work on the complicated model. Moreover, we discuss the future work to further study on addressing the accuracy of the boundaries with the adjustment of slicing thickness.

null

['Luo, Shuncun', 'Wang, Zemin', 'Zeng, Xiaoyan']

2021-11-18T00:53:04Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90379', 'http://dx.doi.org/10.26153/tsw/17300']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['high entropy alloy', 'selective laser melting', 'microstructure', 'strength']

Study on the Formability, Microstructures and Mechanical Properties of AlCrCuFeNix High-Entropy Alloys Prepared by Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6defb58a-5cd6-4326-85fc-775b8989cc68/download

University of Texas at Austin

Because of easy cracking caused by rapid solidification, fabricating dual-phase high-entropy alloys (DP-HEAs) through selective laser melting (SLM) has hardly been achieved. Here we reasonably design new DP-HEAs specific to SLM according to solid solutions formation criterion and HEA definition. Results show that Ni addition favors the formation of face-centered cubic (FCC) phase and facilitates the transition from columnar to equiaxed grains, thus the formability of AlCrCuFeNix (2.0 ≤ x ≤ 3.0) HEAs is improved. The SLMed AlCrCuFeNi3.0 HEA exhibits remarkably heterogeneous microstructures, such as modulated nanoscale lamellar or cellular dual-phase structures, and possesses the best combination of the ultimate tensile strength (~ 957 MPa) and ductility (~ 14.3 %). Also, it is discovered that high densities of Cr-enriched nano-precipitates are embedded in the ordered body-centered cubic (B2) phase. Finally, the underlying strengthening mechanisms are analyzed for the SLMed AlCrCuFeNi3.0 HEA.

null

['Arumaikkannu, G.', 'Anilkumar, N.', 'Saravanan, R.']

2021-09-23T22:17:35Z

9/10/08

Mechanical Engineering

null

['https://hdl.handle.net/2152/88037', 'http://dx.doi.org/10.26153/tsw/14978']

eng

2008 International Solid Freeform Fabrication Symposium

Open

['Z510 3DP rapid fabricator', 'process parameters', 'Particle Swarm Optimization', 'mechanical engineering']

Study on the Influence of Rapid Prototyping Parameters on Product Quality in 3D Printing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7ba40443-dfa6-4374-833d-707679de29cf/download

null

This work aims at evaluating the relative significance of the input parameters on the product quality produced by Z510 3DP rapid fabricator. Taguchi’s L18 orthogonal array was employed to investigate the possible process parameters including binder setting saturation value (shell & core), layer thickness, and build orientation. Using a surface profilometer and CMM, a series of measurements in evaluating the 3DP products surface finish and dimensional accuracy has been carried out. Nonlinear regression model was developed and a statistical analysis was done to determine the significant factors affecting the product quality of the fabricated products. Optimal process parameter settings were proposed using Particle Swarm Optimization technique. The results were validated by conducting the confirmatory experiments.

null

['Yang, Hwa-Joon', 'Jang, Tae-Sik', 'Ryu, Choong-Ryeol', 'Lee, Il-Yup']

2019-11-21T18:12:20Z

2003

Mechanical Engineering

null

['https://hdl.handle.net/2152/78552', 'http://dx.doi.org/10.26153/tsw/5608']

eng

2003 International Solid Freeform Fabrication Symposium

Open

Prototype-Car

A Study on the Manufacturing of Large Size Hollow Shape Parts for Prototype-Car Using Rapid Prototyping Technology and Vacuum Molding

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e113b932-d06a-43db-82e8-e3a632bb51da/download

null

Rapid Prototyping(RP) techniques have revolutionized traditional manufacturing methods. These techniques allow the user to fabricate a part directly from a conceptual model before investing in production tooling and help develop new models with significant short time. This paper suggests the new process to manufacture large size hollow shape parts for prototype-car using Rapid Prototyping technology and Vacuum Molding with the reduction of delivery time. In addition, this paper introduces the dividing and combining method to make large size RP master model in spite of the limit of the build chamber dimensions of commercialized RP systems and post-processing method to achieve sufficient surface quality.

null

['Jiang, Kaiyi', 'Guo, Yanling', 'Bourell, David L.']

2021-10-11T20:53:17Z

8/16/13

Mechanical Engineering

null

['https://hdl.handle.net/2152/88641', 'http://dx.doi.org/10.26153/tsw/15575']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['selective laser sintering', 'wood plastic composite', 'microstructure', 'binding mechanism', 'energy usage', 'Eucalyptus/PES', 'mechanical interlock']

Study on the Microstructure and Binding Mechanisms of Selective Laser Sintered Wood Plastic Composite

Conference paper

https://repositories.lib.utexas.edu//bitstreams/984fe35d-8085-4c99-9217-87b3ed271163/download

University of Texas at Austin

A new type of wood plastic composite, Eucalyptus/PES(Polyethersulfone) blend, was developed. It was designed to be used in LS (Laser Sintering) with reduced energy usage with cost savings. The preparation of Eucalyptus/PES blend and part sintering were under fixed processing conditions and parameters. Through mechanical testing, it was discovered that the strength of prototypes is low due to the formation of a segregated structure in the composite and a weak wood fiber–plastic particle interface. The specific focus of this paper was on investigating the microstructure and binding mechanisms between these two materials. Combining SEM technology and infrared spectrum analysis, the interface binding form of the wood fiber and PES was confirmed to be mechanical interlock. Also the size and distribution of wood fiber in the PES matrix, which can affect the binding and strengthening mechanism, were analyzed during sintering and crack extension.

null

Liu, Jie

2021-09-30T13:05:14Z

2010

Mechanical Engineering

null

['https://hdl.handle.net/2152/88226', 'http://dx.doi.org/10.26153/tsw/15167']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['vibration-suspense-type', 'powder-coating', 'SLS', 'Polystyrene-Al', 'Selective Laser Sintering']

Study on Vibration-Suspense-Type Metal Powder-Coating Process for Selective Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b8557a8e-eee9-434a-a3d2-825bc56492d1/download

University of Texas at Austin

In this paper, Vibration-suspense-type process is used to develop a new material, metal or porcelain powder coated with resin or ceramic powder, then it can be sintered and formed without large-power laser. One set of vibration-suspense-type powder-coating equipment is developed and powder material suitable for SLS can be prepared with the equipment. The moving status and the moving process of powder granule in the vibration-suspense-type process are also analyzed. Based on the equipment, Polystyrene- Al powder material, which is suitable for SLS, is successfully prepared. And the optimum process is discussed.

null

['Sui, Guanghua', 'Zhang, Wei', 'Leu, Ming C.']

2019-09-23T16:31:26Z

2000

Mechanical Engineering

null

['https://hdl.handle.net/2152/75957', 'http://dx.doi.org/10.26153/tsw/3056']

eng

2000 International Solid Freeform Fabrication Symposium

Open

Prototyping

Study on Water Deposit in Rapid Freeze Prototyping Process 342

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c477523b-155d-4770-8386-703c0a4af8eb/download

null

Rapid Freeze Prototyping (RFP) builds a three-dimensional ice part according to its CAD model by depositing and rapidly freezing water in a layer-by-layer manner. To study the water deposit in RFP, assumptions are made based on the deformation of water droplet impinging on a flat substrate, the thermal analysis of a new layer of water deposit, and the characteristics of solidification of a water drop. The equations governing the cross-sectional profile of the water deposit are then established. A model of water deposit is proposed by simplifying the equations under our experimental conditions in RFP. By using this model, equations for layer thickness of vertical and slant walls built by RFP are derived and verified by experiments

null

['Pekin, Senol', 'Bukowski, John', 'Zangvil, Avigdor']

2019-02-28T18:38:26Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73510', 'http://dx.doi.org/10.26153/tsw/660']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['FDC', 'DSC']

A Study on Weight Loss Rate Controlled Binder Removal From Parts Produced by FDC

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8a21a059-9d8e-4d76-ad86-5651204a1488/download

null

The binder removal schedule of a binder in the ethylene vinyl acetate-wax system was analyzed by automatically adjusting the soaking duration based on the monitored weight loss of the polymer. The thermolysis of several grades of microcrystalline wax and ethylene vinyl acetate have been analyzed by TvA and DSC to support the explanation of the weight loss rate controlled binder removal experiments. During the thermolysis ofsuch binders in air, the degradation sequence is degradation and evaporation of hydrocarbons, degradation ofthe vinyl acetate, and degradation of the ethylene chain, all oxygen assisted. It was shown that the extent and the rate of the vinyl acetate degradation in air is determined by the molecular weight of the EVA, unlike its degradation in N2• It was concluded that thermolysis of light polymers is easier than that ofthe heavy ones and weight loss rate controlled binder removal technique can help in the optimization of binder removal schedule for a variety of polymers.

null

['Hilton, Zachary T.', 'Newkirk, Joseph W.', "O'Malley, Ronald J."]

2021-11-02T15:31:22Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89831

eng

2017 International Solid Freeform Fabrication Symposium

Open

['chromium-nickel equvalency', 'Cr-Ni', 'stainless steel', 'chemistry', 'additive manufacturing']

Studying Chromium and Nickel Equivalency to Identify Viable Additive Manufacturing Stainless Steel Chemistries

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1922586b-eb06-4f1d-801f-e07121298c32/download

University of Texas at Austin

Chromium and nickel equivalency modeling has long been used in welding to determine the weldability of steel chemistries. A study was conducted to determine the applicability of Cr-Ni modeling to the additive manufacturing process. Many AM methods involve rapid solidification of small melt pools, similar to welding. Chemistries with varying Cr/Ni ratios were selected for use in a selective laser melting process and modeled using known models. Initial results indicate that the standard “safe welding zone” may not directly apply to additive manufacturing. The capability to build with chemistries outside the weldability “safe zone” could result in improved and varied properties for additively manufactured materials.

null

['Aremu, A.', 'Ashcroft, I.', 'Hague, R.', 'Wildman, R.', 'Tuck, C.']

2021-09-30T20:04:54Z

9/23/10

Mechanical Engineering

null

['https://hdl.handle.net/2152/88291', 'http://dx.doi.org/10.26153/tsw/15232']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'finite element based topology optimisation', 'optimisation', 'structural optimization', 'alogrithm', 'SIMP algorithm', 'BESO algorithm']

Suitability of SIMP and BESO Topology Optimization Algorithms for Additive Manufacture

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c14954fb-2a4b-4c08-950d-a80433ebf9f5/download

University of Texas at Austin

Additive manufacturing (AM) is expanding the range of designable geometries, but to exploit this evolving design space new methods are required to find optimum solutions. Finite element based topology optimisation (TO) is a powerful method of structural optimization, however the results obtained tend to be dependent on the algorithm used, the algorithm parameters and the finite element mesh. This paper will discuss these issues as it relates to the SIMP and BESO algorithms. An example of the application of topological optimization to the design of improved structures is given.

null

['Gopalakrishna, B.', 'Bourell, David L.']

2018-05-03T19:55:47Z

1993

Mechanical Engineering

doi:10.15781/T27P8TX1P

http://hdl.handle.net/2152/65074

eng

1993 International Solid Freeform Fabrication Symposium

Open

['SLS', 'SFF', 'SLPS', 'Supersolidus Liquid Phase Sintering']

Supersolidus Liquid Phase Selective Laser Sintering of Prealloyed Bronze Powder

Conference paper

https://repositories.lib.utexas.edu//bitstreams/061d2a9a-6c3c-4caf-8061-d5aa445abe2f/download

null

['Mohajeri, Babak', 'Khajavi, Siavash H.', 'Nyberg, Timo', 'Khajavi, Siamak H.']

2021-10-18T22:44:21Z

2014

Mechanical Engineering

null

https://hdl.handle.net/2152/89279

eng

2014 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'supply chains', 'supply chain modifications', 'decentralized production system']

Supply Chain Modifications to Improve Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6989efd1-cd5b-4d99-992e-a9147aab8b64/download

University of Texas at Austin

Additive manufacturing (AM) offers unique production characteristics which among those, toollessness and production of complex geometries are potentially significant to operations efficiency. Previous research has illustrated the potential sufficiency of this technology to affect the supply chains‟ arrangements and enabling decentralized production configurations. While, one of the important advantages of AM enabled distributed production is the increased flexibility, which is a necessity in today‟s competitive and ever changing global supply chains, number of obstacles have kept this method from wide implementation. In this paper, we study the possible supply chain modifications to decrease the cost of an AM-enabled decentralized production system. In other words, we perform a cost-benefit analysis on various AM supply chain strategies in a spare parts context to realize the independent operational factors affecting the implementation cost of additive manufacturing. Moreover, we analyze the ways to adapt the supply chain management to enable full potential of AM considering the present technology.

null

['Chalsani, Kumar', 'Jones, Larry', 'Roscoe, Larry']

2018-11-02T14:19:07Z

1995

Mechanical Engineering

doi:10.15781/T2JQ0TD9X

http://hdl.handle.net/2152/69330

eng

1995 International Solid Freeform Fabrication Symposium

Open

['Rapid prototyping', 'fused deposition modeling process', 'STL']

Support Generation for Fused Deposition Modeling

Conference paper

https://repositories.lib.utexas.edu//bitstreams/fa990638-73db-4ec2-be78-a7fcf546c0dd/download

null

With the growth of the use of Rapid Prototyping (RP) systems, there has been a corresponding growth in the complexity of parts expected from the various RP processes. To meet the demand for increasingly more intricate and detailed prototypes, the technology has matured and improved, allowing RP users to build these parts faster, better and with a variety of materials. Stratasys Inc.'s Fused Deposition Modeling (FDM ®) system is one of the leading prototyping systems available in the market today. Recent enhancements in electro-mechanical control of the machine head have improved the viability of FDM as a system for manufacturing complex prototypes. The FDM-1600 system can now also create detailed parts using ABS, a widely used plastic in the automotive and other industries. In addition, we have further reduced the lead time (preprocessing or operator time) in the product design cycle with the inclusion of an automatic support generation module in Stratasys' proprietary QuickSlice® software product. QuickSlice processes STL data to generate machine code to drive the FDM system.

null

['Lufeng, Chen', 'Ruosong, Liu']

2021-12-06T23:47:05Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90722', 'http://dx.doi.org/10.26153/tsw/17641']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['support-free hollowing', '3+2-axis printing', 'additive manufacturing']

Support-Free Hollowing for 3+2-Axis Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/722e0b0d-bc09-4beb-8468-a0a751969294/download

University of Texas at Austin

Additive manufacturing (AM), also known as 3d printing, has become a hot topic in academia and industry in the past decades. For a typical layer-based additive manufacturing where the object is printed in a layer-by-layer fashion, the battle to reduce or even eradicate the support structure is always faced by researchers and industrial practitioners. The newly emerging multi-axis printing platform inspired by the five-axis machine tool opens new directions, such as surface quality improvement, support-free printing, etc. In this paper, we have presented a framework for the support-free hollowing of 3+2-axis printing. A suite of algorithms including curved skeleton extraction, print sequence optimization, hollowing generation, and print path planning is introduced. It is expected that the print efficiency will increase while the residue artifacts caused by the support structure on the contact surface can be ultimately eradicated.

null

['Stevinson, B. Y.', 'Bourell, D. L.', 'Beaman Jr., J. J.']

2020-02-28T21:51:16Z

9/14/06

Mechanical Engineering

null

['https://hdl.handle.net/2152/80124', 'http://dx.doi.org/10.26153/tsw/7145']

eng

2006 International Solid Freeform Fabrication Symposium

Open

Selective laser sintered

Support-Free Infiltration of Selective Laser Sintered (SLS) Silicon Carbide Preforms

Conference paper

https://repositories.lib.utexas.edu//bitstreams/66063177-b704-45c2-b06f-690c0db7a00f/download

null

Non-metallic objects are often difficult to manufacture due to high melting temperatures, poor sinterability, limited ductility, and difficulty in machining. Freeform fabrication techniques coupled with liquid infiltration offer a cost-effective and rapid manufacturing mechanism for composite parts with complex geometry and adequate properties. Selective laser sintered (SLS) silicon carbide (SiC) preforms infiltrated with liquid silicon develop localized infiltrant overextrusions onto surfaces and at surface irregularities. Several shrinkage mechanisms including densification were studied as possible causes of these overfilling extrusions, and the results are discussed below. This research was supported by NSF Grant Number DMI-0522176.

null

['Jangam, John Samuel Dilip', 'Anthony, Thomas', 'McKinnell, Jim', 'Pon, Ben', 'Piderman, Jake', 'Zhao, Lihua']

2023-01-27T18:01:41Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117351', 'http://dx.doi.org/10.26153/tsw/44232']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Binder jetting', 'sintering', 'support structures', 'distortion']

Support-Free Sintering of 3D Printed Binder Jet Copper and Stainless Steel Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e5ffbe4b-0b60-4352-85a5-b5e571f354f1/download

null

Binder jet additive manufacturing involves selectively applying a binder, layer-by-layer, to produce green parts, followed by a high temperature sintering treatment. During sintering, green parts are inherently prone to undesired part distortion/sag in the unsupported regions. Traditional methods use 3D printed supports or machined ceramic setters to avoid the part distortion/sag during sintering. We introduce a shape-retaining-stimulus coating that will mitigate/eliminate the need of additional supports during sintering. Simply supported coper and stainless steel green parts of various thickness were evaluated for part distortion. Our experimental results demonstrate that a selective application of the shape-retaining-stimulus coating on 3D printed copper parts with a spanning up to 50 mm, and stainless steel parts spanning up to 33 mm can be sintered without auxiliary supports. Our shape-retaining-stimulus coating produces exceptional results, and the ease of removal makes it an attractive candidate.

null

['Jangam, John Samuel Dilip', 'Anthony, Thomas', 'McKinnell, Jim', 'Pon, Ben', 'Piderman, Jake', 'Zhao, Lihua']

2023-01-31T13:56:33Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117367', 'http://dx.doi.org/10.26153/tsw/44248']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Binder jetting', 'sintering', 'support structures', 'distortion']

Support-free sintering of 3D printed binder jet copper and stainless steel parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ba997a29-49c0-4e21-b876-f6908c38b859/download

null

Binder jet additive manufacturing involves selectively applying a binder, layer-by-layer, to produce green parts, followed by a high temperature sintering treatment. During sintering, green parts are inherently prone to undesired part distortion/sag in the unsupported regions. Traditional methods use 3D printed supports or machined ceramic setters to avoid the part distortion/sag during sintering. We introduce a shape-retaining-stimulus coating that will mitigate/eliminate the need of additional supports during sintering. Simply supported coper and stainless steel green parts of various thickness were evaluated for part distortion. Our experimental results demonstrate that a selective application of the shape-retaining-stimulus coating on 3D printed copper parts with a spanning up to 50 mm, and stainless steel parts spanning up to 33 mm can be sintered without auxiliary supports. Our shape-retaining-stimulus coating produces exceptional results, and the ease of removal makes it an attractive candidate.

null

Kanada, Yasusi

2021-10-19T17:49:24Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89308

eng

2014 International Solid Freeform Fabrication Symposium

Open

['fused deposition modeling', 'layer-less', 'filament-stacking', 'horizontal stacking']

Support-less Horizontal Filament-Stacking by Layer-less FDM

Conference paper

https://repositories.lib.utexas.edu//bitstreams/28601298-197f-48ea-9b32-797923a4a3dc/download

University of Texas at Austin

null

This paper proposes a layer-less fused-deposition-modeling (FDM) method, which enables mostly horizontal stacking of filament without support material and which can avoid seams easily.

null

['Deppe, Gereon', 'Koch, Rainer']

2021-10-26T17:58:34Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89541

eng

2016 International Solid Freeform Fabrication Symposium

Open

['Multi Attribute Decision Making', 'MADM', 'additive manufacturing', 'aerospace']

Supporting the Decision Process for Applying Additive Manufacturing in the MRO Aerospace Business by MADM

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e09adb4b-b2e7-4e97-b5d1-9df5022e5844/download

University of Texas at Austin

The spare part industry in aerospace is highly demanding. For conventional manufacturing technologies it is difficult to meet these requirements. In contrast to that, the design freedom of Additive Manufacturing enables the production of complex and lightweight parts. The lack of experience with this technology hampers the decision where Additive Manufacturing can be economically applied. The cost drivers have to be newly evaluated and holistically investigated. Supply chain advantages have to be considered during the decision process, too. Therefore, aerospace characteristics are analyzed within the paper and a methodology based on Multi Attribute Decision Making (MADM) is introduced. To do so, the cost appraisal for Additive Manufacturing has to be detailed. Additionally, changes in the supply chain have to be identified and quantified. Quality criteria have to be taken into account as well. In the end it is shown how these influence factors can be combined to create a decision support.

null

['Ramos, Jorge A.', 'Bourell, David L.', 'Beaman, Joseph J.']

2019-10-25T16:10:27Z

2002

Mechanical Engineering

null

['https://hdl.handle.net/2152/77443', 'http://dx.doi.org/10.26153/tsw/4532']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Laser Polished

Surface Characterization of Laser Polished Indirect-SLS Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/349dac0c-d3da-4b14-a3b4-60aa5a379cab/download

null

Surface analysis was performed on laser polished indirect-SLS samples made from 420 stainless steel sintered powder - bronze infiltrated. The goal was to determine variations from the as-received condition in surface chemical composition, morphological structure, presence of contaminants as well as the formation of new phases. Comprehensive characterization of the laser polished surfaces was performed using scanning electron microscopy (SEM), energy dispersive spectrochemical analysis (EDS), x-ray diffraction analysis (XRD) and Vickers hardness. A large quantity of carbon (i.e. > 29 wt%) was present on the as-received surface mostly from the polymer binder present in the green part. Although surface-shallow-melting is the principal mechanism for the roughness reduction of the as-received surface, the chemical composition of the latter after processing changed to a higher carbon and oxygen content and a lower copper content. Additionally, clusters were formed periodically over the polished surface consisting of Fe, Cr, Si and Al oxides. The surface analysis demonstrated that the laser polished surfaces differ significantly more from a morphological rather than a microstructural perspective.

null

['Tumer, Irem Y.', 'Thompson, David C.', 'Crawford, Richard H.', 'Wood, Kristin L.']

2018-10-10T15:36:16Z

1995

Mechanical Engineering

doi:10.15781/T2SJ1B965

http://hdl.handle.net/2152/68756

eng

1995 International Solid Freeform Fabrication Symposium

Open

['SLS', 'manufacturing process', 'functional prototyping']

Surface Characterization of Polycarbonate Parts from Selective Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e7394da3-c667-410f-b732-862b881b29ce/download

null

Surfaces of polycarbonate Selective Laser Sintering parts are investigated to determine the characteristics affecting part quality. Surfaces are obtained from experiments by varying four factors, namely, layer thickness, laser power, part orientation, and build angle. First, spatial modes on SLS surfaces are decomposed using a qualitative spectral analysis in an attempt to find their origins. Thermal modes on the top surfaces of polycarbonate SLS parts result in the other modes being obscured; melting and part curl are concluded to be the dominant modes on these surfaces. Furthermore, surface modes resulting from building the part at an angle to the powder bed are identified and modeled. Then, mathematical measures are computed for the surfaces to determine surface precision quantitatively. An analysis-of-variance study is performed to reveal the trends in surface precision with respect to control factors. Surface precision is shown to change significantly with laser power and part orientation, and trade-offs with part strength are presented.

null

['Li, Yangsheng', 'Xue, Lijue']

2021-09-28T18:12:18Z

9/18/09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88141', 'http://dx.doi.org/10.26153/tsw/15082']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['non-contact freeform surface measurement', 'short range laser displacement sensor', 'surface measurement', 'laser displacement sensor']

Surface Contour Measurement Using a Short Range Laser Displacement Sensor

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5e480f5b-3619-4581-a701-82a6b43692b5/download

University of Texas at Austin

Non-contact freeform surface measurement is widely used in industry. To acquire the surface data, a laser displacement sensor and a motion system are typically used. One of the factors that affect the measuring accuracy is the sensor’s resolution. A high resolution sensor usually has a short measuring range. However, an unknown component’s profile with a large peak-to-valley height variation can not usually be measured using a short range sensor. We designed and developed a measuring system based on an existing 3-axis motion system with a laser displacement sensor mounted on its Z axis. This measuring system can be easily integrated to an existing laser processing system by standard communication ports to extend its applications into tool path planning, in-line inspection and monitoring. With the developed system, the real-time distance from the sensor to the component surface is acquired, and used as a feedback signal to control the sensor’s position on the Z axis to automatically maintain its distance with a given value. Through this development, the measuring range of the system is extended from the sensor’s measuring range up to the Z axis travelling range of the motion system so that a surface with large peak-to-valley height variation can be easily measured by a short range sensor with substantially improved accuracy.

null

['Shi, Dongping', 'Gibson, Ian']

2019-02-18T17:44:28Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73393', 'http://dx.doi.org/10.26153/tsw/545']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['Rapid Prototyping', 'Selective Laser Sintering']

Surface Finishing of Selective Laser Sintering Parts with Robot

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f6e399c1-9702-410b-b161-ff5173b9b9d8/download

null

Compared with conventional subtractive manufacturing technologies, RP has great benefits in shortening the design-manufacture cycle time of a product. Even ifmechanical properties are not considered, most RP products still cannot be directly used in applications until the requirements for overall surface quality are satisfied. To improve the overall surface quality of Selective Laser Sintering parts, a robotic finishing system has been developed as a part of an ongoing research project. A finishing tool is held by a robot and moved according to programmed paths generated from the original CAD model data. This paper describes the experimental system in detail and shows that the surface roughness, dimensional accuracy, and geometrical accuracy can be improved.

null

['Vaithilingam, Jayasheelan', 'Goodridge, Ruth D.', 'Christie, Steven D.', 'Edmondson, Steve', 'Hague, Richard J.M.']

2021-10-05T19:16:21Z

2012

Mechanical Engineering

null

['https://hdl.handle.net/2152/88414', 'http://dx.doi.org/10.26153/tsw/15353']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', 'SLM', 'self-assembled monolayers', 'SAMs']

Surface Modification of Selective Laser Melted Structures Using Self-Assembled Monolayers for Biomedical Applications

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2c41bf7a-9a7d-4570-ab3c-6340894a81f9/download

University of Texas at Austin

The potential of the selective laser melting (SLM) process to fabricate biomedical implants has been studied widely in recent years due to its ability to build complex and customised structures. Although SLM is capable of building almost any desired geometry, the surface properties of the produced parts are not controlled by the process and may not be suitable for many applications. Hence in this study, the coating of self-assembled monolayers (SAMs) onto SLM fabricated Ti6Al4V structures to modify surface chemistry has been studied. 16-phosphanohexadecanoic acid monolayers were used to modify SLM as-fabricated (SLM-AF) and mechanically polished (SLM-MP) surfaces. X-ray photoelectron spectroscopy (XPS) and static water contact angle measurements confirmed the formation of monolayers on these surfaces. The covalently bonded monolayers were found to be stable for up to six weeks immersion in Tris-HCl buffer solution. Stability of monolayers on SLM-AF and SLM-MP was not significantly different. This study demonstrates the possibility of forming stable phosphonic acid monolayers on SLM fabricated Ti6Al4V surfaces.

null

['Han, C.J.', 'Chen, X.', 'Tan, J.W.', 'Yao, Y.', 'Wei, Q.S.', 'Zhang, Z.', 'Shi, Y.S.']

2021-10-20T21:42:23Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89368

eng

2015 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', 'Co-Cr scaffold', 'surface modification', 'bone implants']

Surface Modification on a Porous Co-Cr Scaffold Fabricated by Selective Laser Melting for Bone Implant Applications

Conference paper

https://repositories.lib.utexas.edu//bitstreams/59d02da5-d4ab-44db-8753-b48f5a8e4f17/download

University of Texas at Austin

Cobalt–chromium–molybdenum alloys with porous structures can be fabricated by additive manufacturing technique, which are attractive for use as scaffolds for bone implant applications. However, metallic implant are difficult to bond directly to living bone due to limited implant interface problems. Therefore, surface modification with scaffold material is required to improve bio-compatibility and the interface surface. In this study, a porous Co-Cr scaffold fabricated by selective laser melting was modified by electrodeposition with biocompatible silk fibroin. The surface characteristics of porous scaffold before and after surface modification were evaluated with the atomic force microscopy, scanning electron microscopy, X-ray diffraction, water contact angle measurement. The mechanical properties including elastic modulus and compressive strength, were determined by compression tests.

null

['Jagdale, Shweta Hanmant', 'Theeda, Sumanth', 'Ravichander, Bharath Bhushan', 'Kumar, Golden']

2023-03-28T19:21:07Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117667', 'http://dx.doi.org/10.26153/tsw/44546']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Laser Powder Bed Fusion', 'SS316L', 'Microhardness', 'Design of Experiments', 'Taguchi', 'Surface Roughness']

Surface Morphology and Hardness of Powder Bed Fused Ss316l as a Function of Process Parameters

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a9582502-f88a-44b5-89c4-f63cf985b406/download

null

Laser powder bed fusion is an emerging additive manufacturing process to fabricate fully dense complex metal parts with high accuracy. Laser process parameters such as, laser power, hatch spacing, scan speed, scan strategy and layer thickness play a major role in defining the quality of the as-built parts. Stainless steel 316L (SS316L) is known for its excellent corrosion resistance, high tensile strength, and high-performance at elevated temperatures. SS316L is used in many applications in the field of automotive, aerospace, medical and heavy equipment industries. In the current study, experiments are designed using Taguchi method to understand the effect of process parameters on the mechanical properties of as-built SS316L parts. Surface roughness of as-built parts is characterized by using digital optical microscopy. The relative density and Vickers microhardness are measured for the as-built parts. Finally, an optimal processing region for laser process parameters is identified.

null

['Kyogoku, H.', 'Shimizu, Y.', 'Yoshikawa, K.']

2021-10-12T17:52:39Z

2013

Mechanical Engineering

null

['https://hdl.handle.net/2152/88705', 'http://dx.doi.org/10.26153/tsw/15639']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', 'surface morphology', 'titanium', 'process parameters', 'process map']

Surface Morphology of Selective Laser-Melted Titanium

Conference paper

https://repositories.lib.utexas.edu//bitstreams/179c9679-f33e-4d5c-b403-03165d36ee91/download

University of Texas at Austin

The surface morphology of biomaterials is one of the most important biocompatibility factors. In this paper, the change in surface morphology of selective laser-melted titanium with process parameters was investigated to control the pore structure and mesh size. First, the process map which shows the relation between the morphology of laser-melted track and the process parameters such as laser power and scan speed was drawn by experiments. The laser-melted layer was fabricated on the basis of the process map. As a result, the surface morphology, especially pore structure and mesh size, of the layer is affected strongly by energy density as well as scan spacing.

null

['Chen, Runrun', 'Fernandes, Axel', 'Ma, Changyu', 'Huang, Shuyi', 'Zheng, Shiqi', 'Barros, Natan', 'Ho, Nhut', 'Li, Bingbing']

2023-02-09T19:05:35Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117443', 'http://dx.doi.org/10.26153/tsw/44324']

eng

2022 International Solid Freeform Fabrication Symposium

Open

bone

Surface Polishing for Additively Manufactured Titanium Bone Scaffolds to Improve Osseointegration

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d958a7ab-1f8d-48e8-99c9-de32b6bb507e/download

null

This research focuses on the porous design, metal additive manufacture and surface polishing methods of Ti6Al4V alloy scaffolds for bone implants and tissue regeneration, with varying lattice structures and pore sizes in the range of 250-350 microns using a selective laser melting (SLM) system Renishaw AM400. Lack of fusion in additive manufacturing results in partially sintered metal particles on both interior and exterior surfaces of porous titanium scaffolds, which necessitates the investigation of seeking an effective polishing method for removing the partially melted particles on the surface of an intricate designed porous implant to achieve a better surface morphology and roughness that augments osseointegration. In this paper, three polishing methods were examined. The experimental result shows that the electropolishing method is capable of effectively removing the incompletely fused particles but it is noteworthy that the parameters controlled during the experiment are crucial to preserve the lattice structure. Rotary abrasive flow polishing method is worth investigating in depth, if better control the direction and rate of flow, the better surface morphology and roughness can be achieved. Lastly, the ultrasonic polishing method was explored to investigate the dependence on the vibratory amplitude control.

null

['Eidt, Wesley', 'Tatman, Eric-Paul', 'McCarther, Josiah', 'Kastner, Jared', 'Gunther, Sean', 'Gockel, Joy']

2021-11-30T21:07:30Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90550', 'http://dx.doi.org/10.26153/tsw/17469']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['surface roughness', 'process parameter', 'laser powder bed fusion', 'additive manufacturing']

Surface Roughness Characterization in Laser Powder Bed Fusion Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e22271d7-bd0c-4d9a-81bd-e4705ca06323/download

University of Texas at Austin

null

This work investigates the influence of processing parameters on the surface roughness for vertical surfaces and surfaces at a downward facing angle.

null

['Ramos, J.A.', 'Murphy, J.', 'Wood, K.', 'Bourell, D.L.', 'Beaman, J.J.']

2019-10-09T15:57:03Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76144', 'http://dx.doi.org/10.26153/tsw/3233']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Enhancement

Surface Roughness Enhancement of Indirect-SLS Metal Parts by Laser Surface Polishing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1fc8cfc8-5634-43b0-8dfd-56e87b063f38/download

null

Laser polishing by means of shallow surface melting of indirect-SLS metal parts was achieved using high power CO2 and Nd:YAG lasers raster scanned at high speed. This was an effective technique for reducing surface roughness. The fast moving laser beam provides just enough heat energy to cause melting of the surface peaks. The molten mass then flows into the surface valleys by surface tension, gravity and laser pressure, thus diminishing the roughness. Surface roughness Ra data were obtained by profilometry measurements of the polished samples. An analytical model was developed based on the assumption that the surface of an SLS part consists of semi-spherical caps. The model was used to predict the Ra values as a function of laser power, scan speed and precursor powder particle size. The modeled results fit the empirical data within a 15% error.

The Laboratory of Freeform Fabrication gratefully acknowledges the support of the Office of Naval Research for funding the project “Surface Engineering for SFF Processes”, Grant Nº: N00014-00-1-0334

null

['Delfs, P.', 'Töws, M.', 'Schmid, H.-J.']

2021-10-21T18:31:50Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89421

eng

2015 International Solid Freeform Fabrication Symposium

Open

['Additive Manufacturing', 'surface quality', 'building orientation', 'layer alignment']

Surface Roughness Optimized Alignment of Parts for Additive Manufacturing Processes

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b45d0cb4-8310-4603-9fcd-3295d3335c80/download

University of Texas at Austin

The layered structure of Additive Manufacturing processes results in a stair-stepping effect of the surface topographies. In general the impact of this effect strongly depends on the build angle of a surface, whereas the overall surface roughness is caused by the resolution of the specific AM process. The aim of this work is the prediction of the surface quality in dependence of the building orientation of a part. These results can finally be used to optimize the orientation to get a desired surface quality. As not every area of a part can be optimized, a predetermination of areas can be used to improve the surface quality of important areas. The model uses the digital STL format of a part as this is necessary for all AM machines to build it. Each triangle is assigned with a roughness value and by testing different orientations the best one can be found. This approach needs a database for the surface qualities. This must be done separately for each Additive Manufacturing process and is shown exemplary with a surface topography simulation for the laser sintering process.

null

['Evans, Rachel', 'Gockel, Joy']

2021-12-01T22:59:00Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90647', 'http://dx.doi.org/10.26153/tsw/17566']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['surface roughness', 'processing parameters', 'layer geometry', 'laser powder bed fusion', 'additive manufacturing']

Surface Roughness Variation in Laser Powder Bed Fusion Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/43528753-f2f6-4233-9d7c-89324235e0a2/download

University of Texas at Austin

The surface roughness of an additively manufactured part produced through laser powder bed fusion has a significantly higher roughness than surfaces produced through traditional manufacturing processes. This roughness can have a significant impact on mechanical properties such as the fatigue life. Additionally, there is still a lack of understanding of the variation of the surface roughness and the appropriate metrics to represent the surface. This work presents line of sight measurements across several large surfaces with changing processing parameters and layer geometry. The measured areas are divided into regions where surface measurement metrics are calculated, and the surface variation within and across the surface is discussed. The calculated metrics and variation are related to the expected impact that the surface will have on the mechanical performance. Results from this research will provide guidance towards surface roughness metric specifications to ensure quality parts with consistent mechanical performance.

null

['Nuttall, D.W.', 'Elliott, A.M.', 'Post, B.K.', 'Love, L.J.']

2021-11-01T22:12:07Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89776

eng

2016 International Solid Freeform Fabrication Symposium

Open

['surface scanning', 'digital scanning', 'large-scale 3D printing', 'large-scale FDM printing', 'fused deposition modeling', 'watercraft layup tooling']

Surface Scanning Methods and Large-Scale FDM Printing for the Replication of Watercraft Layup Tooling

Conference paper

https://repositories.lib.utexas.edu//bitstreams/41ec7115-d465-4b9f-98fc-9fa96864fdab/download

University of Texas at Austin

The manufacturing of tooling for large, contoured surfaces for fiber-layup applications requires significant effort, with traditional methods for the auto industry using hand sculpted clay, and the marine pleasure-craft industry typically creating forms from foam lay-up, then hand cut or machined down from a billet. Oak Ridge National Lab’s Manufacturing Demonstration Facility (ORNL MDF) collaborated with Magnum Venus Products to develop a process for reproducing legacy whitewater adventure craft via digital scanning and large scale 3-D Printing molds. The process entailed scanning a legacy canoe, converting to CAD, additively manufacturing the mold, and subtractively finishing the transfer surfaces. The outlined steps were performed on a specific canoe geometry, with intent to develop energy efficient, marketable processes for replicating complex shapes related to watercraft, and provide products for demonstration to the composites industry. It is anticipated that developing this process to manufacture tooling for complex contoured surfaces will have direct applicability to the sports/pleasure craft industry, naval and other watercraft, as well as bathrooms and large trucks.

null

['Sachs, Emanuel', 'Curodeau, Alain', 'Gossard, David', 'Jee, Haeseong', 'Cima, Michael', 'Caldarise, Salvatore']

2018-09-26T19:55:23Z

1994

Mechanical Engineering

doi:10.15781/T2SN01P5J

http://hdl.handle.net/2152/68591

eng

1994 International Solid Freeform Fabrication Symposium

Open

['3D Printing', 'metal matrix', 'CAD']

Surface Texture by 3D Printing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/05ec48e2-c415-4fa2-8ea2-1489ff9abb7b/download

null

Three Dimensional Printing is a solid freeform fabrication process which creates parts directly from a computer model by depositing in layers. Each layer is created by depositing powder and selectively joining the powder with binder applied by a modulated ink-jet printhead. This paper explores the application of 3D Printing to the manufacture of surface textures, where the geometric freedom of 3D Printing is used to create repetitive millimeter and sub-millimeter surface structures with overhangs and undercuts. A related aspect of the work concerns the development of computer representations of these complex structures. In one investigation, a "mushroom field" surface texture was modeled and printed. Each mushroom consists of a cylinder with a ball on top. These features are printed in a hexagonal array with each feature parallel to the local surface normal of a complex curved surface. In another investigation, textures were printed into ceramic molds. The textures were transferred to metal (tin-lead, CoCr) castings as positive surface features with overhangs and undercuts and typical dimensions of 700 x 350 x 350Jlm. The application ofsuch cast textures to bone flXation in orthopaedic implants is discussed.

null

['Yang, Li', 'Gu, Hengfeng', 'Lassell, Austin']

2021-10-12T21:45:35Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88749', 'http://dx.doi.org/10.26153/tsw/15683']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['electropolishing', 'surface treatment', 'Ti6Al4V', 'powder bed fusion', 'direct metal laser sintering', 'electron beam melting', 'additive manufacturing']

Surface Treatment of Ti6Al4V Parts Made By Powder Bed Fusion Additive Manufacturing Processes using Electropolishing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7185cea7-7b06-462f-aab9-684f519b93ac/download

University of Texas at Austin

This paper investigated the use of electropolishing on the surface treatment of the Ti6Al4V parts made by the powder bed fusion processes including direct metal laser sintering (DMLS) and electron beam melting (EBM). A non‐aqueous alcohol based electrolyte was used, and the relationship between the process and surface roughness was evaluated. Based on the results, the feasibility of electropolishing as a potential alternative post‐surface treatment for additive manufactured metal parts was discussed.

null

['Reutzel, E.W.', 'Nassar, A.R.']

2021-10-12T22:17:30Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88753', 'http://dx.doi.org/10.26153/tsw/15687']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['metal-based additive manufacturing', 'additive manufacturing', 'laser-based deposition', 'directed-energy deposition', 'closed-loop control', 'build-plan']

A Survey of Sensing and Control Systems for Machine and Process Monitoring of Directed-energy, Metal-based Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d8519e5b-7b0e-4aa2-87b6-1925bed79cf5/download

University of Texas at Austin

Additive manufacturing of metal parts is, even in the simplest of cases, a complex undertaking. Parts typically involve hundreds or thousands of individual laser or electron-beam deposits, each of which involve a complex interaction between energy source, feedstock, and substrate. During deposition, many of the independent process variables that contribute to overall build quality— such as travel speed, feedstock flow pattern, energy distribution, gas pressure, etc.—are subject to perturbations from systematic fluctuations (such as changing build geometry or growing global temperature) and random external disturbances (such as spatter on a cover lens). Such process variations affect final part quality, including dimensional tolerance, microstructure, and properties. Researchers have utilized a wide variety of sensor data and analysis for quality monitoring and real-time control of the component geometry, microstructure, and properties. Process attributes that have been targeted for measurement and control include melt pool geometry, temperature, and layer build-height; process parameters that have been utilized for control include processing-head stand-off, substrate angle, travel speed, material feed-rate, and beam power. Here, we survey many of these methods for laser-based, directed-energy deposition, and briefly discuss recently-introduced methods for real-time, closed-loop control of build-plan.

null

['Sreenivasan, Rameshwar', 'Bourell, David L.']

2021-09-28T19:36:04Z

9/15/09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88163', 'http://dx.doi.org/10.26153/tsw/15104']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['sustainability', 'Selective Laser Sintering', 'energy standpoint', 'electrical power', 'Eco-Indicators']

Sustainability Study in Selective Laser Sintering – An Energy Perspective

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8ff8c21a-ed8d-4e58-ab88-a01353157298/download

University of Texas at Austin

This paper presents a sustainability analysis of Selective Laser Sintering (SLS) from an energy standpoint. Data of electrical power consumed by the system over an entire build were acquired using a LabVIEW 8.6 circuit. The power drawn by individual subsystems were also measured, and an energy balance was performed. These data were then used to arrive at a Total Energy Indicator of the process with the help of a specific type of Environmental and Resource Management Data (ERMD) known as Eco-Indicators, which indicates the level of sustainability of the process.

null

['Lau, Sharon', 'Yeazel, Taylor', 'Miller, Ana', 'Pfister, Nathan', 'Rivero, Iris V.']

2021-11-09T21:01:11Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90165', 'http://dx.doi.org/10.26153/tsw/17086']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['3D printing', 'pores', 'polyvinyl alcohol', 'PVA', 'hydrogel', 'cross-linking']

A Sustainable Additive Approach for the Achievement of Tunable Porosity

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3a74e1ca-0b7a-466f-8a4b-d38be5916438/download

University of Texas at Austin

This study aims to design a green additive approach for the fabrication of controlled porosity on hydrogels. Although hydrogels have been of common use in tissue engineering, the generation of controllable porosity remains an issue due to their swelling and degradation properties. Hydrogels in this study were fabricated by physical cross-linking and the porosity was generated by casting the solution in a 3D printed mold prior to physical cross-linking. This approach eliminates the use of chemical cross-linking compounds which are often toxic and not environmentally friendly. Polyvinyl alcohol was selected to validate this technique due to its biocompatibility and adequate mechanical properties. The microstructure, mechanical properties and deformation of the porous hydrogels were characterized. Results revealed that the proposed bioplotting technique reduced variation of pore size and allotted for the realization of controlled and tunable pore structures.

null

['Heidrich, James R.', 'Gervasi, Vito', 'Kumpaty, Subha']

2019-10-18T17:05:17Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76263', 'http://dx.doi.org/10.26153/tsw/3352']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Tetralattice

Synthesis of a Compact Tetralattice Heat Exchanger using Solid Freeform Fabrication and Comparison Testing Against a Tube Heat Exchanger

Conference paper

https://repositories.lib.utexas.edu//bitstreams/09d9febc-b516-4871-b6d6-d19ad7b937f0/download

null

The challenge for Solid Freeform Fabrication (SFF) lies in fabricating complex parts that are not possible by conventional manufacturing means. The goal was to apply SFF techniques to complex geometry heat exchangers. The heat exchanger structure is modeled after the covalently bonded carbon atoms of a diamond. The tetrahedron diamond lattice, or Tetralattice, is a repeating lattice unit that forms a network of channels to form the heat exchanger. Electroforming methods creating Tetralattice were applied to synthesize an air-oil compact heat exchanger. After production, the heat exchanger was tested and compared with an industry standard heat exchanger for performance evaluation.

null

['Agarwala, Mukesh K.', 'Bourell, David L.', 'Manthiram, Arumugam', 'Birmingham, Britton R.', 'Marcus, Harris L.']

2018-05-03T20:00:42Z

1993

Mechanical Engineering

doi:10.15781/T2QR4P760

http://hdl.handle.net/2152/65078

eng

1993 International Solid Freeform Fabrication Symposium

Open

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

Synthesis, Selective Laser Sintering and Infiltration of High Super Tc Dual Phase Ag-YBa2Cu307-x Superconductor Composites

Conference paper

https://repositories.lib.utexas.edu//bitstreams/eb073840-6090-4ac3-811d-883beaec374f/download

null

Fine, homogeneous dual phase Ag-YBa2Cu307-x composite powders were prepared by a simple colloidal sol-gel co-precipitation technique. Silver did not react with or degrade YBa2Cu307-x. Bulk porous samples of pure YBa2Cu307-x and Ag-YBa2Cu307-x were made from powders by Selective Laser Sintering. The porous parts were further densified by infiltrating silver into pores, resulting in a dense, structurally sound dual phase superconducting composite. Laser processing parameters were varied to obtain optimum microstructure. The laser sintered parts required oxygen annealing after infiltration to restore the orthorhombic, superconducting structure. X-ray diffraction and Tc measurements indicate some impurity phases present in samples processed under aggressive laser conditions.

null

['Foroozmehr, Ehsasn', 'Sarrafi, Rouzbeh', 'Hamid, Syed', 'Kovacevic, Radovan']

2021-09-29T14:21:57Z

9/15/09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88180', 'http://dx.doi.org/10.26153/tsw/15121']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['metal-ceramic composites', 'laser cladding', 'powder deposition', 'slurry erosion']

Synthesizing of Functionally Graded Surface Composites by Laser Powder Deposition

Conference paper

https://repositories.lib.utexas.edu//bitstreams/915aa3ae-a5e3-4598-bb69-2c584df813c8/download

University of Texas at Austin

Metal-ceramic composites are used extensively in surface modification. Laser cladding, as one of the surface treatment techniques, shows a promising method to deposit functionally graded layers of metal-ceramic composite. In this study, AISI 4140 and nickel as the matrix and tungsten carbide (WC), titanium carbide (TiC), and nano-WC as the ceramic parts are used in four different combinations for deposit on AISI 4140 substrates. The volume percentage of the ceramics is increased from the bottom to the top. The microstructure and micro-hardness of the samples and residual stress of the top surface of the samples are studied and compared.

null

['Qu, Xiuzhi', 'Langrana, Noshir A.']

2019-10-18T15:13:58Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76234', 'http://dx.doi.org/10.26153/tsw/3323']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Extrusion-Based

A System Approach in Extrusion-Based Multi-Material CAD

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0b262d1e-35f2-4c19-9203-08bf2c901ec2/download

null

For extrusion based multi-material Layered Manufacturing (LM) processes, a CAD system has been developed for the Fused Deposition of Multiple Ceramics (FDMC) hardware. This closed loop CAD system includes solid model design & multi-material slicing, multi-material toolpath generation and virtual simulation modules. Intelligent features and an adaptive roadwidth optimum toolpath generation algorithm compute void sizes & their location and generate a void free toolpath [1][2]. The present study focuses on a comprehensive approach, which includes a format that contains the information on the geometry of the multi-material components, the build materials and the necessary fabrication process information. Multi-CAD utilizes computer graphics techniques to visualize the fabricated part. The slicing algorithm is utilized to create multi-material contours, which then are integrated into our previously developed intelligent toolpath system.

null

['Seltzer, D.M.', 'Wang, X.', 'Nassar, A.R.', 'Schiano, J.L.', 'Reutzel, E.W.']

2021-10-20T21:00:04Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89361

eng

2015 International Solid Freeform Fabrication Symposium

Open

['metal-based additive manufacturing', 'part quality', 'feedback control', 'scanning speed', 'laser power', 'melt pool']

System Identification and Feedback Control for Directed-Energy, Metal-Based Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/dc7b2069-ecb9-4332-bc17-9b38b3bca032/download

University of Texas at Austin

Additive manufacturing of metal parts is a complex process where many variables determine part quality. In addition to manipulated process variables, such as travel speed, feedstock flow pattern, and energy distribution, other exogenous inputs also determine part quality. For example, changing build geometry and a growing global temperature. In addition, there are random external disturbances such as spatter on a cover lens. Both manipulated process variables and exogenous inputs affect dimensional tolerance, microstructure, and other properties that determine the final part quality. Our long term aim is to improve part quality through real-time regulation of measurable process variables using vision-based feedback control. As a starting point, we present a process model that relates scanning speed and laser power to build height and melt pool width. These results demonstrate the necessity for using multi-input multi-output feedback control techniques and provide information for refining the frame rate and spectral sensitivity of the imaging system.

null

['Habbal, Osama', 'Kassab, Ali', 'Ayoub, Georges', 'Mohanty, Pravansu', 'Pannier, Christopher']

2024-03-26T20:18:39Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124392', 'https://doi.org/10.26153/tsw/51000']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['fused filament fabrication', 'additive manufacturing', 'extrusion dynamics', 'spreading dynamics']

System Identification of Fused Filament Fabrication Additive Manufacturing Extrusion and Spreading Dynamics

Conference paper

https://repositories.lib.utexas.edu//bitstreams/443870c3-b62a-49dc-b49f-48dafb3dd18e/download

University of Texas at Austin

In fused filament fabrication additive manufacturing, polymer extrusion and spreading dynamics affect build quality in both surface finish and mechanical properties. The state of the art in extrusion modeling and control is identification and compensation of a fixed first order pole with a linear model of the system. However, physical nonlinearities cause deviation of this pole in practice. To advance the aim of slicing using accurate nonlinear dynamic models, this work presents a system and procedure for automated measurement of dynamic bead extrusion. The system uses a belt printer, iFactory3D One Pro, with nozzle tilted 45 degrees from the build belt, and a snapshot 3D scanner. Single layer prints in polylactic acid (PLA) are scanned and then automatically ejected. The gcode for the single bead print holds the gantry speed fixed or extrusion speed constant while the extrusion flow rate or gantry speed is varied as a step input signal in space. The experiment design matrix varied two variables: gantry speed and extrusion flow rate. Time constants are fitted to bead area signals that are extracted from the scan data to obtain nonlinear models. Depending on the experiment condition, the percent difference between the highest time constant and the lowest time constant ranged from 279% to 61%, confirming the high nonlinearity of the extrusion system in FFF 3D printers. Additionally, measurements are performed on a cartesian 3D printer with a 2D scanner to test applicability of the methods to a general audience and verify observed trends. It was observed that larger steps in extrusion velocity for a constant X-Axis velocity, yielded smaller time constants, while the same steps in velocity using a constant extrusion velocity condition with variable X-Axis velocity, yielded the opposite trend. Moreover, the time constants for a step up in extrusion velocity yielded higher overall values in time constant when compared to step down conditions.

null

['Boddu, Mallikharjuna R.', 'Landers, Robert G.', 'Musti, Srinivas', 'Agarwal, Sanjeev', 'Ruan, JianZhong', 'Liou, Frank W.']

2019-10-25T16:00:38Z

2002

Mechanical Engineering

null

['https://hdl.handle.net/2152/77438', 'http://dx.doi.org/10.26153/tsw/4527']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Laser Aided

System Integration and Real-Time Control Architecture of a Laser Aided Manufacturing Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/546170f8-c443-4273-810d-1a750c9381eb/download

null

This paper discusses a hybrid deposition–removal manufacturing system being developed at the University of Missouri–Rolla. The system consists of a laser system, five–axis CNC machining center, and powder feeder system. A description of the control software, real–time control architecture, and integration of various subsystems to build the hybrid system is given. The interaction of the real–time controller with various sensors and subsystems to monitor and regulate the process is presented. The communication between integrated process planning for the system and real–time control is also discussed in this paper.

The authors gratefully acknowledge the financial support of the National Science Foundation (DMI–9871185), Missouri Research Board, Society of Manufacturing Engineers (#02022–A), and Missouri Department of Economic Development.

null

['Ardis, Abel', 'Alvarez Andrade, Andres', 'McNamara, Justin', 'Ahrens, Anthony', 'Janysek, Jason', 'Humble, Jamie', 'Asiabanpour, Bahram']

2021-10-11T22:23:15Z

2013

Mechanical Engineering

null

['https://hdl.handle.net/2152/88666', 'http://dx.doi.org/10.26153/tsw/15600']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['reverse engineering', 'fabricated parts', 'part accuracy', 'feature taxonomy', 'trend error']

A Systematic Use of Reverse Engineering in Evaluating the Overall Accuracy of the Fabricated Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/80b3711d-c716-4676-8685-ca96d807f394/download

University of Texas at Austin

In this paper a systematic approach is proposed that evaluates the overall accuracy of a part. In this approach, by using the feature taxonomy, a part is decomposed into primitive features. Then, each feature is compared to the original CAD. Features are evaluated based on their size, form, orientation, and position. Laser scanning technique is used to collect a feature’s data and its conversion into CAD data. To reduce data processing time for non-freeform features, manual digital dial indicators were customized and used for data collection. To process and evaluate the part’s accuracy, statistical and CAD methods are applied. One benefit of the proposed hybrid system is that different errors can be differentiated and separated. In this study the manual method and statistical line fitting showed that, in addition to the surface quality deviation error, there was a trend error in the data; as the part got closer to the front right side of the printer it was steadily increasing. Further observations clarified that the trend error is caused by the build orientation; as the printer lays down a new layer of powder it drags the previous layer binder and powder from the back of the printer to the front of the printer.

null

['Lieneke, T.', 'Adam, G.A.O.', 'Leuders, S.', 'Knoop, F.', 'Josupeit, S.', 'Delfs, P.', 'Funke, N.', 'Zimmer, D.']

2021-10-19T20:38:02Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89334

eng

2015 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'dimensional tolerance', 'dimensional deviations', 'linear dimensions']

Systematical Determination of Tolerances for Additive Manufacturing by Measuring Linear Dimensions

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b67e6f84-9ebb-4d68-92d1-42a9a75dca11/download

University of Texas at Austin

Additive manufacturing offers many technical and economical benefits. In order to profit from these benefits, it is necessary to consider the manufacturing limits and restrictions. This applies in particular to the geometrical accuracy. Therefore, the achievable geometrical accuracy needs to be investigated, which enables the determination of realistic tolerances. Thus, two different aims are considered. The first aim is the determination of dimensional tolerances that can be stated if additive manufacturing is used under normal workshop conditions. Within the second aim, relevant process parameters and manufacturing influences will be optimized in order to reduce dimensional deviations. To achieve both aims a method was developed first. This method identifies relevant influential factors on the geometrical accuracy for the processes Fused Deposition Modeling (FDM), Laser Sintering (LS) and Laser Melting (LM). Factors were selected that are expected to affect the geometrical accuracy mainly. The first investigations deal with measuring linear dimensions on a designed test specimen and the derivation of achievable dimensional tolerances. This paper will present both, the developed method and the first results of the experimental investigations.

null

Wozny, Michael

2018-04-18T17:31:23Z

1992

Mechanical Engineering

doi:10.15781/T2X63BP0R

http://hdl.handle.net/2152/64363

eng

1992 International Solid Freeform Fabrication Symposium

Open

['CAD model', 'CAD geometry', 'SFF']

Systems Issues in Solid Freeform Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/266f5e65-0a9d-4368-9b37-2b9ec2044cf7/download

null

This paper is concerned with the systems aspects of the Solid Freeform Fabrication (SFF) technology, i.e., the issues that deal with getting an external geometric CAD model to automatically control the physical layering fabrication process as directly as possible, regardless ofthe source of the model. The general systems issues are described, the state of systems research is given, and open research questions are posed.

null

['Li, X.P.', 'Dadbakhsh, S.', 'Vanmeensel, K.', 'Vleugels, J.', 'Van Humbeeck, J.', 'Kruth, J.P.']

2021-11-02T14:09:12Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89808

eng

2017 International Solid Freeform Fabrication Symposium

Open

['commercially pure titanium', 'Mo2C', 'selective laser melting']

Tailoring Commercially Pure Titanium Using Mo2C During Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e9223372-88a9-454d-84b2-b5355b409279/download

University of Texas at Austin

Commercially pure Ti (CP Ti), Ti alloys and Ti composites have applications in a wide range of industries. With the merits of the emerging additive manufacturing technique, e.g. layer-wise fabrication and rapid solidification rate, the fabrication of Ti composites with tailorable microstructure and hence controllable properties is possible. In this work, a Ti composite was fabricated through selective laser melting (SLM) of CP Ti with Mo2C, consisting of a matrix mainly from α-Ti and a small amount of β-Ti which could potentially embed very fine existing particles. The influence of SLM on the phase formation and microstructure of the fabricated Ti composite was investigated. The results showed that a tailorable microstructure of the Ti composite can be achieved via SLM. This work provides fundamental and important information on the fabrication of Ti composites with controllable microstructure through SLM of CP Ti with ceramic particle additions.

null

['Quiñonez, Paulina A.', 'Bermudez, Diego', 'Ugarte-Sanchez, Leticia', 'Roberson, David A.']

2021-11-18T01:48:58Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90400', 'http://dx.doi.org/10.26153/tsw/17321']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['shape memory polymers', 'physical properties', 'fused deposition modeling', 'additive manufacturing']

Tailoring Physical Properties of Shape Memory Polymers for FDM-type Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/bfdb14aa-f0da-485a-9acb-88a9a7faaa41/download

University of Texas at Austin

Inclusion of shape memory polymers into additive manufacturing technologies based on fused deposition modeling (FDM™) can greatly increase the usefulness of this fabrication platform. Materials compatible with FDM™ such as polylactic acid (PLA) are known to exhibit shape memory properties, however aspects such as shape recovery and shape fixation are not tunable. The work presented here entails the initial development and characterization of shape memory polymers intended for FDM™-type additive manufacturing platforms. Here, two polymers with differing shape memory mechanisms (dual component and dual state) were combined in iterative ratios leading to material systems with tunable physical properties. Dynamic mechanical analysis (DMA) was used to determine the critical thermal parameters while polymer crystallinity was determined via x-ray diffraction (XRD). Scanning electron microscopy (SEM) was used to characterize the fracture morphology of impact test specimen.

null

['Majewski, C. E.', 'Toon, D.', 'Zarringhalam, H.', 'Hopkinson, N.', 'Caine, M. P.']

2020-03-10T17:28:44Z

9/10/08

Mechanical Engineering

null

['https://hdl.handle.net/2152/80234', 'http://dx.doi.org/10.26153/tsw/7253']

eng

2008 International Solid Freeform Fabrication Symposium

Open

Rapid Manufacturing

Tailoring the Mechanical Properties of Selective Laser Sintered Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1f3e4d8c-eb3f-47d0-85c3-acfc366c0684/download

null

The ~£1 million IMCRC-funded integrated project ‘Personalised Sports Footwear: From Elite to High Street’ is investigating the use of Rapid Manufacturing to produce personalised sports shoes, with the aim of enhancing performance, reducing injury, and providing improved functionality. Research has identified that, for sprinting, performance benefits can be achieved by tuning the bending stiffness of a shoe to the characteristics of an individual athlete. This paper presents research to date on several novel methods of influencing the mechanical properties of Selective Laser Sintered shoe soles, with a particular focus on stiffness.

null

['Pu, Jing', 'Saleh, Ehab', 'Ashcroft, Ian', 'Jones, Arthur']

2021-11-18T16:35:49Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90419', 'http://dx.doi.org/10.26153/tsw/17340']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['additive manufacture', 'fused filament fabrication', 'feedstock production', 'continuous carbon fibre PEEK printing', 'composites printing']

Technique for Processing of Continuous Carbon Fibre Reinforced PEEK for Fused Filament Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/bc46a57a-2b96-45b4-92c3-604f484f6c14/download

University of Texas at Austin

3D printing of light-weight and mechanically-strong structures facilitates several applications. 3D printing of continuous carbon fibre reinforced polyetheretherketone (PEEK) presents exciting possibilities as the high stiffness and strength of the high-performance plastic PEEK reinforced with carbon fibre are paired with the agility of the 3D printing process. The Fused Filament Fabrication (FFF) process is used to print these parts, and a pultrusion system was designed and used to produce the filaments since they are not commercially available. This paper describes the design and construction of a pultrusion system within a wider project on carbon fibre reinforced PEEK FFF printing. This system is then used to produce the FFF filament with pultrusion speed and temperature optimisation.

null

['Novae, Andrei', 'Kaza, Srinivas', 'Wang, Zetian', 'Lee, CheoI', 'Thomas, Charles']

2018-11-16T16:30:57Z

1996

Mechanical Engineering

doi:10.15781/T21N7Z66R

http://hdl.handle.net/2152/70296

eng

1996 International Solid Freeform Fabrication Symposium

Open

['CAD', 'plotter cuts', 'manufacturing techniques']

Techniques for Improved Speed and Accuracy in Layered Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/bedc8351-f485-42d4-bf33-b5c6e6f0d1c9/download

null

The ability to improve the construction accuracy and/or the build speed for layered manufacturing techniques is demonstrated using a series of new techniques: (1) Parts can be decomposed into sections which are constructed in parallel and then assembled. This reduced the build time and material waste for a sheet foam process. (2) A more accurate interface based on direct slicing ofthe CAD model can be used to eliminate the need for the intermediary tessellation file. (3) The layer thickness can be adapted based on the part's geometric complexity to increase the surface quality, build speed, and z-axis accuracy.

null

['Karunakaran, K. P.', 'Pushpa, Vishal', 'Akula, Sreenath Babu', 'Dwivedi, Rajeev', 'Kovacevic, R.']

2020-02-24T14:52:12Z

2005

Mechanical Engineering

null

['https://hdl.handle.net/2152/80075', 'http://dx.doi.org/10.26153/tsw/7096']

eng

2005 International Solid Freeform Fabrication Symposium

Open

['Rapid Prototyping', 'Arc Welding', 'CNC machining']

Techno-Economic Analysis of Hybrid Layered Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/427a809d-63da-40de-9b3b-c061d88d2f48/download

null

Subtractive manufacturing (CNC machining) has high quality of geometric and material properties but is slow, costly and infeasible in some cases; additive manufacturing (RP) is just the opposite. Total automation and hence speed is achieved in RP by compromising on quality. Hybrid Layered Manufacturing (HLM) developed at IIT Bombay combines the best features of both these approaches. It uses arc welding for building near-net shapes which are finish machined to final dimensions. High speed of HLM surpasses all other processes for tool making by eliminating NC programming and rough machining. The techno-economic viability of HLM process has been proved through a real life case study. Time and cost of tool making using HLM promises to be substantially lower than that of CNC machining and other RP methods. Interestingly, the material cost in HLM was also found to be lower. HLM is a cheaper retrofitment to any 3 or 5 axis CNC milling machine or machining center.

null

['Haeckel, Felix', 'Meixlsperger, Maximilian', 'Burkert, Torsten']

2021-11-08T22:51:24Z

2017

Mechanical Engineering

null

['https://hdl.handle.net/2152/90064', 'http://dx.doi.org/10.26153/tsw/16985']

eng

2017 International Solid Freeform Fabrication Symposium

Open

['laser beam melting', 'technological challenges', 'part quality', 'automotive series', 'automotive']

Technological Challenges for Automotive Series Production in Laser Beam Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8b370a7a-5fd2-4b40-9810-3a3e67ca081a/download

University of Texas at Austin

Compared to traditional production methods, Additive Manufacturing enables a tool free production leading to higher flexibility, freedom of design and lightweight potential. For these reasons the BMW Group is proceeding from the production of prototypes to the direct series production of parts. For metal components, the process of selective Laser Beam Melting is able to realize these potentials. Aside from the economic issues, technological challenges also have to be met. Among them is achieving consistent part quality in the production of same parts. To achieve technical specifications compliant in series production, a defined process stability and reproducibility of the part properties is needed. This reproducibility is investigated for the process of selective Laser Beam Melting. Also variables which have the biggest impact on the part quality throughout a simulated series production are being examined. Thus the reproducibility of the process can be quantified. To guarantee a high and stable part quality in the future, approaches are being developed to monitor or systematically prevent influences, which are found to have a negative effect on the process quality.

null

['Rohde, J.', 'Lindemann, C.F.', 'Jahnke, U.', 'Kruse, A.', 'Koch, R.']

2021-11-08T23:28:50Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90075', 'http://dx.doi.org/10.26153/tsw/16996']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['process chain', 'technology integration', 'additive manufacturing', 'SMEs']

Technology Integration into Existing Companies

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4b2c0ffe-be7b-4730-b9b0-fad5209e18af/download

University of Texas at Austin

The implementation of additive manufacturing as an industrial manufacturing process poses extraordinary challenges to companies due to their far-reaching differences to conventional processes. In addition to the major differences in the production process, the pre and post process steps in particular also require a rethinking for companies and their employees. To overcome these challenges and specifically to assist SMEs in the integration of technologies five industrial companies are researching together within research project "OptiAMix", funded by the German Federal Ministry of Education and Research (BMBF) and coordinated by the Paderborn University. This paper focuses on the development of an optimal and standardized process chain and its implementation in a general integration methodology. This enables the standardized integration of additive manufacturing in order to create a uniform understanding of the procedures and tasks within the company for the industrial application of additive manufacturing at an early stage as well as the full exploitation of its high potentials. Therefore, the methodology also includes other technology-specific components such as strategic component selection, decision support for "make or buy" and the implementation of automated component marking.

null

['Sammons, Patrick', 'Bollineri, Sahit', 'Sibal, Ritika', 'Barton, Kira']

2021-11-04T15:09:06Z

2017

Mechanical Engineering

null

['https://hdl.handle.net/2152/89982', 'http://dx.doi.org/10.26153/tsw/16903']

eng

2017 International Solid Freeform Fabrication Symposium

Open

['process behavior', 'temperature', 'relative humidity', 'electrohydrodynamic jet printing', 'e-jet printing', 'optical adhesives']

Temperature and Humidity Variation Effect on Process Behavior in Electrohydrodynamic Jet Printing of a Class of Optical Adhesives

Conference paper

https://repositories.lib.utexas.edu//bitstreams/db968022-f316-452e-a91e-e9d60f9d0d39/download

University of Texas at Austin

Electrohydrodynamic jet (e-jet) printing is an emerging additive manufacturing process that utilizes an electric field to eject material from a micro-/nano-scale microcapillary nozzle. Due to its contemporary nature and the complex physics which govern the process, little is known about printing behavior sensitivity with respect to environmental condition variability. The aim of this work is to construct a systematic experimental design to test and evaluate the relationship between two environmental variables, temperature and relative humidity, and key process metrics initiating ejection voltage, printing frequency, and diameter of material ejected. A factorial statistical design of experiments is used to investigate the parameter space. Results are used to identify temperature and humidity ranges that give robust printing regimes for a specific class of optical adhesives. Best-fit curves are determined for several of the input-output relationships, which provide a predictive model for the ink behavior.

null

['Keller, Bernd', 'Pfeifer, Rolf', 'Su, Wei-Nien', 'Eyerer, Peter']

2019-02-26T20:18:06Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73495', 'http://dx.doi.org/10.26153/tsw/645']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['PET', 'IR-spectroscopy']

Temperature Dependent Optical Properties of Polymers as a Basis for Laser Process Modeling

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d2b73423-75a6-4b4f-a632-d304cc73bc7c/download

null

The knowledge of laser absorption is essential to describe the behavior of polymers in different laser processes, i.e. SLS, LOM, etc. By means of transmission IR-spectroscopy a method for measuring temperature dependent penetration depths (absorption length) of polymers, especially at a wavelength of 10.6Jlm (C02-Laser), is developed. Results for the laser sintering materials polystyrene (PS), nylon 11 (PA 11), nylon copolymer (CoPA) and polyethylene terephtalate (PET) are presented. It is detected that the absorption length of polymers will increase or decrease significantly dependent on temperature. This paper will point out simplified methods based on the one dimensional heat transfer equation with volume heat source to set the processing parameters i. e. for the SLS process. The calculations correspond with the measured data.

null

['Josupeit, Stefan', 'Schmid, Hans-Joachim']

2021-10-19T18:26:07Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89318

eng

2014 International Solid Freeform Fabrication Symposium

Open

['laser sintering', 'part cakes', 'temperature distribution', 'temperature history', 'process quality']

Temperature History within Laser Sintered Part Cakes and Its Influence on Process Quality

Conference paper

https://repositories.lib.utexas.edu//bitstreams/aa533013-631f-42d2-b140-6456bb1b5621/download

University of Texas at Austin

The temperature distribution and history within laser sintered part cakes is an important aspect regarding the process quality and reproducibility of the polymer laser sintering process. Especially the temperature history during the build and cooling phase is decisive for powder ageing effects and the development of part quality characteristics. In this work, a measurement system for three-dimensional in-process temperature measurements is set up and the influence of different parameters on the inner part cake temperature distribution and history is analyzed. Important factors are not only geometrical build job parameters like the part packing density and build height, but also process parameters like the layer thickness and bulk powder density. Individual in-process temperature profiles at different positions within a part cake are finally correlated with powder ageing effects. The results of this work help to understand the temperature history dependency of powder and part properties and can therefore be used to develop optimized process controls.

null

Benda, J.A.

2018-10-03T15:56:18Z

1994

Mechanical Engineering

doi:10.15781/T2W08X194

http://hdl.handle.net/2152/68655

eng

1994 International Solid Freeform Fabrication Symposium

Open

['laser sintering', 'stereolithography', 'thermal gradients']

Temperature-Controlled Selective Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d224ae3e-07f4-47e5-b961-383d779bd2eb/download

null

A control scheme for laser sintering has been developed which maintains sintering powder at constant temperature by actively controlling laser power. It uses a sensor to monitor the temperature of powder at the focus of a moving laser beam. The control scheme corrects for variations ofthermal conductivity and powder reflectivity due to the proximity of previously sintered material, as well as for statistical fluctuations. The sensor also serves as a useful diagnostic, and is used to confirm model predictions ofthe variation of powder temperature with process parameters. A second temperature-controlled laser beam, concentric with the first, but of larger spot size, can be used to locally heat the powder around the sintering powder. This is shown to reduce curling as well as the balling or agglomeration of molten material

null

['Li, C.', 'Liu, J.F.', 'Guo, Y.B.', 'Li, Z.Y.']

2021-10-21T17:12:59Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89409

eng

2015 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', 'temperature thread', 'distortion', 'multiscale simulation']

A Temperature-Thread Multiscale Modeling Approach for Efficient Prediction of Part Distortion by Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/00ad3a84-82ef-4596-8eae-7150685d25bf/download

University of Texas at Austin

Selective laser melting (SLM) is a powder bed based additive manufacturing process to manufacture functional parts. The high-temperature process will produce large tensile residual stress which leads to part distortion and negatively affect product performance. Due to the complex process mechanism and coupling multi-physics phenomena, the micro-scale single laser scan modeling approach is not practical to predict macro part distortion since it demands an exceedingly long computational time. In this study, a temperature-based multiscale modeling approach has been developed to simulate material phase transition of powder-liquid-solid for fast prediction of part distortion. An equivalent body heat flux obtained from the micro-scale laser scan can be imported as “temperature-thread” to the subsequent layer hatching process. Then the hatched layer with temperature filed can be used as a basic unit to build up the macro-scale part with different scanning strategies. The temperature history and residual stress fields during the SLM process were obtained. In addition, the part distortion can be predicted with a reasonable accuracy by comparing with the experimental data.

null

['Ariadi, Y.', 'Rennie, A.E.W.']

2021-09-23T22:05:21Z

9/10/08

Mechanical Engineering

null

['https://hdl.handle.net/2152/88034', 'http://dx.doi.org/10.26153/tsw/14975']

eng

2008 International Solid Freeform Fabrication Symposium

Open

['Computer Aided Design', 'design template', 'mass customisation', 'product family architecture', 'Additive Layer Manufacturing']

Templates for Consumer Use in Designing Customised Products

Conference paper

https://repositories.lib.utexas.edu//bitstreams/dc2b6be7-d183-4334-a828-3054ae21c851/download

null

This research proposes a new design system for consumers who would use the product to run an easy-to-operate design and selection tool by themselves instead of conventional Computer Aided Design (CAD). In terms of manufacturing the product, several studies focus on involving the consumer as much and as early as possible. However, recent developments of Additive Layer Manufacturing (ALM) technologies have led to a renewed interest in allowing the consumers to develop customised products. As a result, manufacturing is being brought closer to consumers. This paper would simplify the CAD stages by utilising design templates for consumer use in customising additive layer manufactured products.

null

['Watanabe, Narumi', 'Shofner, Meisha L.', 'Rosen, David W.']

2021-11-02T19:14:06Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89869

eng

2017 International Solid Freeform Fabrication Symposium

Open

['polypropylene composites', 'material extrusion', 'additive manufacturing', 'tensile properties', 'process simulation']

Tensile Mechanical Properties of Polypropylene Composites Fabricated by Material Extrusion

Conference paper

https://repositories.lib.utexas.edu//bitstreams/09ba610a-27ac-4e19-a479-b1052d569e60/download

University of Texas at Austin

In the material extrusion additive manufacturing process, a thin filament of material is deposited in a layer-by-layer manner to fabricate a three dimensional part. The filament deposition pattern can result in voids and incomplete bonding between adjacent filaments in a part, which leads to reduced mechanical properties. Further, the layer-by-layer deposition procedure typically results in mechanical property anisotropy, with higher properties in the layer compared to those across layers. The study reported in this paper explored various polypropylene composite formulations to address these issues: low residual stress and warpage, good mechanical properties, and reduced anisotropy. The reduction in anisotropy will be the focus of this paper as a function of thermal properties and process variable settings. A series of process simulation models was developed to explore ranges of thermal properties and process settings, which provided insights into tensile specimen behaviors. Results demonstrate that anisotropy can be reduced almost completely if the material can be formulated to have low crystallinity, low coefficient of thermal expansion, and moderate to high thermal conductivity (for a polymer).

null

['Raghavan, S.', 'Soh, N.', 'Hao, L.J.', 'Khan, N.A.', 'Muthu, R.', 'Dzugan, J.']

2021-11-30T20:48:42Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90542', 'http://dx.doi.org/10.26153/tsw/17461']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['tensile property', 'wall thickness', 'maraging steel', 'selective laser melting']

Tensile Property Variation with Wall Thickness in Selective Laser Melted Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e2801b97-99cb-44dd-8af7-16c90859ad41/download

University of Texas at Austin

3D printed parts with complex geometries have different section thickness which leads to non-uniform mechanical properties due to microstructure and defect distributions. Hence, it is essential to characterise the localised mechanical properties to obtain a better understanding of the variability. The tensile property variability is captured by testing miniature sized tensile coupons that are extracted from different part locations which is more representative, when compared to testing printed tensile coupons. In the current work a benchmark study was first carried out to correlate miniature tensile properties with ASTM standard tensile test for different wall thickness in SLM Maraging steels. Following this, tensile property variation at different locations in an AM fabricated impeller part was studied. It was observed the thin sections in the part exhibited large variability in the elongation values. The effect of heat treatment on the tensile properties in the impeller was also studied.

null

['Lokhande, Mahendra', 'Crawford, Richard']

2019-10-18T16:46:37Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76257', 'http://dx.doi.org/10.26153/tsw/3346']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Inter-Vertebral

Testing of Compliance in a Prosthetic Socket Fabricated Using Selective Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/030b21dc-1de5-4f18-9e6a-bea613d68a4c/download

null

Solid freeform fabrication techniques offer potential as manufacturing technologies in applications that require custom design. One such application is the fabrication of prosthetic sockets. This paper reports on research to manufacture compliant below-the-knee prosthetic sockets using selective laser sintering (SLS). Compliance in the socket is a critical factor in the level of comfort the amputee experiences during gait. The ability to control local geometry is seen as an advantage of SLS in fabricating compliant sockets. This paper presents work on developing a model of compliance for sockets constructed of Duraform®. The approach taken here is to provide the necessary compliance by controlling the wall thickness of the socket. To select the right thickness, a study of the wall deflection with respect to contact pressure was performed. An experimental testing device was designed and constructed to test the deflection versus pressure for different thicknesses of test circular discs made of Duraform®. The results were correlated to a finite element model. These results will be used for designing the compliance in the walls of prosthetic sockets fitted to actual patients.

null

['Garcia, J.P.', 'Camacho, L.A.', 'Hasanyana, A.', 'Espalin, D.']

2024-03-26T22:52:41Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124434', 'https://doi.org/10.26153/tsw/51042']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['big area additive manufacturing', 'BAAM', 'fracture toughness', 'double catilever beam']

TESTING PROTOCOL DEVELOPMENT FOR FRACTURE TOUGHNESS OF PARTS BUILT WITH BIG AREA ADDITIVE MANUFACTURING

Conference paper

https://repositories.lib.utexas.edu//bitstreams/093a83e1-284e-4d17-bd14-ae71d77631dd/download

University of Texas at Austin

Mechanical testing of additively manufactured parts has largely relied on existing standards developed for traditional manufacturing. While this approach leverages the investment made on current standards development, it inaccurately assumes that mechanical response of AM parts is identical to that of parts manufactured through traditional processes. When considering thermoplastic, material extrusion AM, differences in response can be attributed to an AM part’s inherent inhomogeneity caused by porosity, interlayer zones, and surface texture. Additionally, interlayer bonding of parts printed with large-scale AM is difficult to adequately assess as much testing is done such that stress is distributed across many layer interfaces; therefore, the lack of AM-specific standard to assess interlayer bonding is a significant research gap. To quantify interlayer bonding via fracture toughness, double cantilever beam (DCB) testing has been used for some AM materials, and DCB has been generally used for a variety of materials including metal, wood, and laminates. Mode I DCB testing was performed on thermoplastic matrix composites printed with Big Area Additive Manufacturing (BAAM). Of particular interest was the crack shape and deflection speed during testing. A modernization of the testing process was proposed using visual processing of a recording of the crack propagation to get more accurate calculations. Results discuss the differences when using two crack types and three deflection speeds.

null

['Aman, R.', 'Kitt, A.', 'Corey, Z.', 'Mohr, L.', 'Ruscitto, D.', 'Iyer, N.', 'Rosenberger, B.']

2024-03-26T23:26:43Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124451', 'https://doi.org/10.26153/tsw/51059']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['electron beam directed energy deposition', 'thermal conditions', 'additive manufacturing']

THE EFFECT OF THERMAL CONDITIONS ON PROCESS DEFECTS IN ELECTRON BEAM DIRECTED ENERGY DEPOSITION

Conference paper

https://repositories.lib.utexas.edu//bitstreams/28d1539a-d3ff-45b1-8dc2-33edea957b3f/download

University of Texas at Austin

Observing process defects at size scales and with sufficient confidence relevant to qualification efforts has not yet been achieved in metal AM, so non-destructive testing (NDT) techniques are used to detect porosity within material deposited. NDT costs can be significant and may not achieve targeted resolution due to geometry and material limitations. In this work, in-process monitoring of Electron Beam Directed Energy Deposition (EB-DED) is enhanced to include three thermal history conditions; inter-pass, melt pool superheat and trailing bead temperatures. Quality scenarios are applied to simulate various process conditions during EB-DED at three different thermal conditions within production relevant use cases and resultant process defects are characterized via high throughput computed tomography. Defects are spatially and temporally registered to process conditions observed during EB-DED and statistically mapped to thermal scenarios. Thermal condition has a strong influence on the quantity of observed process defects, with lower interpass temperature resulting in a larger number of defects.

null

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

2024-03-26T16:46:38Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124368', 'https://doi.org/10.26153/tsw/50976']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['laser powder bed fusion', 'nickel base superalloy', 'y precipitate', 'heat treatment effects', 'tensile properties']

THE INFLUENCE OF HEAT TREATMENTS ON THE MICROSTRUCTURE AND TENSILE PROPERTIES OF ADDITIVELY MANUFACTURED INCONEL 939

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b005bfa1-7c35-42c8-a294-952bd3197093/download

University of Texas at Austin

This study investigated the effect of heat treatment variations on the microstructure and tensile properties of laser powder bed fused Inconel 939. Three different heat treatment schedules, all of which comprise stress relief, hot isostatic pressing, solution annealing, and aging, were followed, and resulting changes in microstructure were analyzed using scanning electron microscopy. Tensile tests were conducted on specimens subjected to different heat treatments to evaluate the mechanical properties at room temperature. Microstructural results showed that solution treatment at 1190 °C for 4 h led to better removal of dendritic microstructure, while second-step aging at 850 °C resulted in monomodal distribution of precipitates. However, the second-step aging temperatures from 750 to 800 °C resulted in bi-modal distribution. The optimal heat treatment schedule, which yielded a superior combination of strength and ductility, involved solution treatment at 1190 °C for 4 h and two-step aging at 1000 °C for 6 h and 800 °C for 4 h.

null

['Petersen, Haley E.', 'Sampson, Brad J.', 'Failla, David P.', 'Priddy, Matthew W.', 'McClelland, Zackery B.']

2024-03-26T16:49:30Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124369', 'https://doi.org/10.26153/tsw/50977']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['maraging 300 steel', 'M300', 'laser powder bed fusion', 'L-PBF', 'additive manufacturing']

The Variation of Mechanical Properties of M300 Maraging Steel Manufactured with Varying Process Parameters in Laser Powder Bed Fusion

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f9c67ae4-11cd-48ea-8684-66be7c9408bf/download

University of Texas at Austin

Laser power bed fusion (L-PBF) is a type of additive manufacturing (AM) that uses layers of powdered metal and a laser to manufacture a part in a layer-by-layer fashion. L-PBF uses a variety of process parameters that ultimately determine the overall quality and mechanical properties of a print. The ability to alter parameters allows for the utilization of various metals in this form of AM. Maraging 300 steel (M300) is a material of particular interest due to its combined tensile strength and high strength-to-weight ratio. By using an assortment of parameters and comparing the resulting mechanical properties it can be determined which process parameters result in a more favorable part to be used in a variety of applications. A favorable process parameter set was selected for future use. This study aims to determine which process parameters result in the best overall mechanical properties of M300 manufactured using L-PBF.

null