ccm/sff-papers · Datasets at Hugging Face

['Rajeshirke, Mithila', 'Fidan, Ismail', 'Gupta, Ankit', 'Mäntyjärvi, Kari']

2023-01-20T14:22:44Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117258', 'http://dx.doi.org/10.26153/tsw/44139']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['FRAM', 'Tensile strength', 'Fatigue strength', 'ANOVA', 'Fatigue life']

Fatigue Analysis of Short Carbon Fiber Reinforced Composite Components Manufactured Using Fiber-Reinforced Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/285d2d87-1bc5-4175-84e9-50c0ec911f96/download

null

Fiber-reinforced additive manufacturing (FRAM) has become quite popular in several industries. The technology offers an opportunity to improve the existing mechanical performance of the part. This research study has presented a successful methodology to fabricate the FRAM- based composite parts with improved fatigue properties. Most engineering applications are subjected to cycling loading which makes the fatigue study an important analysis. The scope of this paper is to present the fatigue properties of short carbon fiber-reinforced Polyethylene Terephthalate Glycol (SCFs/PETG) of 13.78% by weight. The fatigue behavior was analyzed by varying the 3D printing process parameters i.e., infill orientation (0°, 45°, and 90°), and infill layer heights (0.2 and 0.3 mm). The tests are carried out on 1600 N as a maximum load of fatigue cycle with a 0.1 stress ratio, for the specimens with 90° and 45° orientations with 0.2 and 0.3 mm layer heights. For 0° orientation, both 0.2 and 0.3 mm layer height specimens are applied to 2600 N as maximum load, keeping the stress ratio the same as 0.1. Analysis of Variance (ANOVA) is used to statistically analyze the testing data to understand the influence of input variables on fatigue properties.

null

['Johnson, Alexander S.', 'Shuai, Shao', 'Shamsaei, Nima', 'Thompson, Scott M.', 'Bian, Linkan']

2021-10-26T20:07:46Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89572

eng

2016 International Solid Freeform Fabrication Symposium

Open

['fatigue', 'failure mechanisms', 'tensile behavior', 'microstructure', 'additive manufacturing', 'superalloys']

Fatigue Behavior and Failure Mechanisms of Direct Laser Deposited Inconel 718

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0e07b124-f008-4088-8bda-b5b02de0ab0e/download

University of Texas at Austin

null

['Lee, Seungjong', 'Pegues, Jonathan', 'Shamsaei, Nima']

2021-11-17T23:42:26Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90357', 'http://dx.doi.org/10.26153/tsw/17278']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'laser beam powder bed fusion', 'LB-PBF', 'surface roughness', 'stainless steel', 'fatigue']

Fatigue Behavior of Additive Manufactured 304L Stainless Steel Including Surface Roughness Effects

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0804b9bc-dab5-45cb-9eec-49650e9a096f/download

University of Texas at Austin

The fatigue behavior of additive manufactured parts in the as-built surface condition is typically dominated by the surface roughness. However, the fatigue behavior of 304L stainless steel fabricated by laser beam powder bed fusion shows less sensitivity to surface roughness under strain-controlled loading conditions than other additive manufactured materials. Under force-controlled conditions, however, the high cycle fatigue resistance is much lower for the as-built surface condition than the machined one. This study investigates the underlying mechanisms responsible for fatigue failure for each condition (i.e. strain-controlled or force-controlled). The corresponding cyclic deformation behavior was characterized, and a thorough fractography analysis was performed to identify the features responsible for crack initiation. Results indicate that the crack initiation features in both loading conditions are similar, and that the reduced high cycle fatigue resistance for force-controlled fatigue loading compared to strain-controlled one is related to differences in the cyclic deformation behavior of the material.

null

['Uhlmann, Eckart', 'Gerlitzky, Georg', 'Fleck, Claudia']

2021-11-02T13:39:54Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89799

eng

2017 International Solid Freeform Fabrication Symposium

Open

['fatigue life', 'post process', 'process chain', 'metal-based additive manufacturing']

Fatigue Behavior of Additive Manufactured Parts in Different Process Chains - An Experimental Study

Conference paper

https://repositories.lib.utexas.edu//bitstreams/54cd37ae-ad55-48db-945d-2829809ecce9/download

University of Texas at Austin

Metal based Additive Manufacturing (AM) has experienced dynamic growth in recent years. However, the global distribution of Additive Manufacturing is limited by the fact the produced parts suffer from bad surface quality and the material properties concerning fatigue life are still an object of current investigations which limits possible applications of AM parts. Due to this fact metal AM processes are often followed by a post process to ensure a better surface quality. In this paper the authors present results where fatigue life and different post processes of additive manufactured parts are investigated. Subsequently, surface roughness, high cycle fatigue, fracture behavior and microstructure have been characterized. Finally the results for the different post processing states have been compared and surface properties as well as microstructure have been correlated with the fatigue properties in order to evaluate how different process chains influence the High cycle fatigue (HCF) behavior of additive manufactured parts.

null

['Johnson, Alexander S.', 'Shrestha, Rakish', 'Nezhadfar, P.D.', 'Shamsaei, Nima']

2021-11-18T00:38:01Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90374', 'http://dx.doi.org/10.26153/tsw/17295']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['Inconel 718', 'fatigue', 'elevated temperature', 'laser beam directed energy deposition']

Fatigue Behavior of Laser Beam Directed Energy Deposited Inconel 718 at Elevated Temperature

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6fcda701-4f8f-48ff-a746-18e22ac24b1b/download

University of Texas at Austin

Nickle based super alloys such as Inconel 718 are being extensively used to manufacture turbine blades for jet engines due to their superior mechanical properties at higher working temperatures. Furthermore, poor machinability associated with Inconel 718 also makes it an attractive material for additive manufacturing processes, which possess the capability to fabricate near net shaped parts. Hence, in this study, the fatigue behavior of Inconel 718 fabricated using laser beam directed energy deposition (LB-DED) is investigated under strain-controlled, fully-reversed conditions at an elevated temperature of 650° C. Fractography analysis was conducted to determine the failure mechanism for additive manufactured Inconel 718 due to higher working temperatures. The results obtained from the fatigue and fractography analysis were then compared with the results obtained from fatigue tests conducted at room temperature. At elevated test temperature, LB-DED Inconel 718 specimens exhibited lower fatigue resistance compared to the tests conducted at the room temperature, primarily in the low cycle fatigue regime. Whereas, in the high cycle fatigue regime the effect of test temperature was observed to be minimal. Furthermore, secondary cracks resulting from the formation of brittle behaving precipitates on the grain boundaries was also evident from the fractography analysis indicating significant changes in the microstructural features of LB-DED Inconel 718 as a consequence of elevated test temperature.

null

['Carrion, Patricio', 'Shamsaei, Nima']

2021-11-18T00:58:47Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90381', 'http://dx.doi.org/10.26153/tsw/17302']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'mean stress', 'variable amplitude', "miner's rule", 'titanium']

Fatigue Behavior of LB-PBF Ti-6Al-4V Parts Under Mean Stress and Variable Amplitude Loading Conditions

Conference paper

https://repositories.lib.utexas.edu//bitstreams/44d53d03-ea13-46b4-9642-a74e24622f69/download

University of Texas at Austin

Additively manufactured components are intended for use in load bearing applications, which are often accompanied by fluctuating external loadings. Therefore, understanding the fatigue behavior of AM materials under variable amplitude loadings is necessary for ensuring reliable in-service component performance. This research focuses on the fatigue behavior of Ti-6Al-4V, fabricated via laser beam powder bed fusion process, under mean stress and variable amplitude loadings. Mean stress effects are investigated under strain-controlled constant amplitude loading under fully-reversed, Rε = -1, and tension-release, Rε = 0, strain ratios. The generated data is used to compare two mean stress models including Morrow and Smith-Watson-Topper. Variable amplitude loading conditions include fully reversed high-low and low-high loading to investigate load sequence and history effects. Finally, cumulative fatigue damage and life predictions are made using the linear damage accumulation model (i.e., Miner’s rule).

null

['Yadollahi, Aref', 'Shamsaei, Nima', 'Thompson, Scott M.', 'Elwany, Alaa', 'Bian, Linkan', 'Mahmoudi, Mohamad']

2021-10-20T22:02:17Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89373

eng

2015 International Solid Freeform Fabrication Symposium

Open

['Selective Laser Melting', '17-4PH stainless steel', 'fatigue behavior', 'tensile properties']

Fatigue Behavior of Selective Laser Melted 17-4 PH Stainless Steel

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7759ce43-d354-42ad-8d58-61da5b0fe719/download

University of Texas at Austin

In this investigation, fully-reversed strain-controlled fatigue tests were conducted on Selective Laser Melted (SLM) 17-4 PH stainless steel (SS). Cylindrical 17-4 PH rods were fabricated vertically-upward using optimized process parameters to ensure a dense product. Post-fabrication heat treatments (solution annealing and aging) were applied on half of the as-built samples. Fatigue behavior and tensile properties of the as-built and heat treated samples were investigated and compared with available data from the literature. The microstructure analysis and fractography were performed to discern the failure initiation sites, crack propagation path, and fracture surface morphology. Fatigue lives of SLM 17-4 PH SS specimens were found to be significantly shorter than their wrought counterparts. It was also found that heat treatment hardens the SLM 17-4 PH SS specimens while also shortens their fatigue life in the high cycle regime. The presence of defects, which serve as crack initiation sites, and more sensitivity of heat treated specimens to impurities, due to higher hardness, were the main reasons for these observations.

null

['Moore, Jacob P.', 'Williams, Christopher B.']

2021-10-06T21:03:53Z

8/20/12

Mechanical Engineering

null

['https://hdl.handle.net/2152/88442', 'http://dx.doi.org/10.26153/tsw/15379']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['direct 3D printing', 'Objet PolyJet', 'elastomer', 'fatigue']

Fatigue Characterization of 3D Printed Elastomer Material

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6fdb60f4-bafe-4c3c-8e90-72f3fd350821/download

University of Texas at Austin

The Objet PolyJet 3D Printing process provides the ability to print graded materials featuring both stiff and elastomeric polymers. This capability allows for a variety of new design possibilities for additive manufacturing such as living hinges, shock absorbing casings, and integrated gaskets. Such design features typically rely upon the ability of traditional elastomers to experience large and repeated strains without permanent deformation or damage. However, voids and other flaws inherent to many Additive Manufacturing (AM) processes can have a significant negative impact on the fatigue life of elastomeric AM materials. In this paper, the authors seek to fill a gap in the literature by characterizing the fatigue life of a direct 3D printed elastomer, and the multi-material interface. Based on the results, the authors offer advice for improving fatigue life of printed elastomeric components.

null

['Wolcott, P.J.', 'Dapino, M.J.']

2021-10-05T19:57:23Z

2012

Mechanical Engineering

null

['https://hdl.handle.net/2152/88422', 'http://dx.doi.org/10.26153/tsw/15361']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['ultrasonic additive manufacturing', 'aluminum 3003 H-18', 'tensile fatigue', 'bond failure']

Fatigue Characterization of Ultrasonic Additive Manufactured Aluminum 3003

Conference paper

https://repositories.lib.utexas.edu//bitstreams/494db52f-16cb-4297-8fd1-5fdbde944506/download

University of Texas at Austin

An aluminum 3003 H-18 block was built using ultrasonic additive manufacturing with process parameters which optimize mechanical strength. Transverse tensile fatigue tests were conducted on samples cut from the block and a stress vs. number of cycles curve was generated. Results show the curve is relatively flat and a stress threshold of 50% of the ultimate transverse tensile strength exists below which failure does not occur within 3.75 × 107 cycles. Optical and scanning electron microscopy conducted on failure surfaces shows no signs of crack initiation or growth typical of fatigue loading, but exhibits areas of no bonding between foil layers. To explain the failure, a model was developed based on the probabilistic failure of bonded areas in tension. The model uses a Frechet distribution to describe the probability of failure at each individual bonded area. Discrete bond failure and subsequent redistribution of stress to the surviving areas eventually leads to failure for the entire sample. Predictions from the model show good correlation with the experimental results.

null

['Banuelos, C.', 'Ramirez, B.', 'De la Cruz, A.', 'Nabil, S.T.', 'Arrieta, E.G.', 'Wicker, R.B.', 'Medina, F.']

2024-03-27T15:39:16Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124484', 'https://doi.org/10.26153/tsw/51092']

en

2023 International Solid Freeform Fabrication Symposium

Open

['laser powder bed fusion', 'flexural stress', 'fatigue endurance', 'additive manufacturing', 'post-processed parts']

Fatigue Endurance Investigation of Post-processed Surfaces of LPBF Ti-6Al-4V under Flexural Stress

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4e35cf89-7e91-42c7-bb7d-a9473d360952/download

University of Texas at Austin

Numerous research works can be found focusing on fatigue properties of AM components, however most of this literature is focused on uniaxial testing. Because the very few actual components under uniaxial loading conditions found in any application, it is also important to investigate fatigue performance under loads that produce combined stresses, such as bending. This project investigates the fatigue endurance of LPBF Ti-6Al-4V specimens subjected to four different surface finishing prost-processes (milled, ground, polished and abrasive media). The test consisted of a force-controlled cyclic load applied on the specimen in a 4-point bending setup until fracture. The study incorporated mechanical and optical techniques to measure and quantify the characteristic surface roughness of the post-processes. Additionally, failure mechanisms are discussed on fractographs. The data analyses suggested that internal defects commonly present in additively manufactured parts had a more significant impact on the fatigue life than surface roughness of post-processed parts.

null

['Muhammad, Muztahid', 'Carrion, Patricio E.', 'Shamsaei, Nima']

2021-11-18T00:14:56Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90366', 'http://dx.doi.org/10.26153/tsw/17287']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'defect size', 'NASGRO', 'fatigue life prediction']

Fatigue Life Prediction of Additive Manufactured Materials Using a Defect Sensitive Model

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5f03c739-314e-4362-8319-8045ff47a0a1/download

University of Texas at Austin

This study utilized a defect sensitive fatigue model based on a fracture mechanics concept to predict the fatigue life of 17-4 precipitation hardening (PH) stainless steel (SS) fabricated using laser beam powder bed fusion (LB-PBF) process. Size of defects such as gas entrapped pores are captured using fractography analysis and calculated employing Murakami’s approach with the √area method. Considering the value of the √area as initial crack length, fatigue life is then calculated using NASGRO software, and compared to the experimental data obtained from strain-controlled fatigue testing. A comparison between predicted fatigue lives using NASGRO software, combined with the Murakami approach, and experimentally obtained ones were presented to determine the applicability of the utilized model for predicting the fatigue performance of additive manufactured materials.

null

['Torries, Brian', 'Shrestha, Rakish', 'Imandoust, Aidin', 'Shamsaei, Nima']

2021-11-10T22:41:22Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90196', 'http://dx.doi.org/10.26153/tsw/17117']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'defects', 'fracture mechanics', 'fatigue modeling']

Fatigue Life Prediction of Additively Manufactured Metallic Materials Using a Fracture Mechanics Approach

Conference paper

https://repositories.lib.utexas.edu//bitstreams/fa317e2b-332f-4914-b109-1ce9bf808c8e/download

University of Texas at Austin

The present study aims to model the fatigue strength of additively manufactured metallic materials employing a fracture mechanics approach. Specimens with different build orientations were subjected to strain controlled fatigue testing. Upon failure, the defect(s) responsible for crack initiation were identified by fractographic analysis. From these defects an equivalent internal defect size is calculated using the √𝑎r𝑒𝑎 method based on Murakami model. Using this parameter, the elastic-plastic energy release rate (𝛥𝐽𝐽𝑒𝑓𝑓) was determined, and the relationship between 𝛥𝐽𝑒𝑓𝑓 and fatigue life was investigated. The results showed that this method improves the predictability of the fatigue strength of additively manufactured materials when the defects size and location is known. The 𝛥𝐽𝑒𝑓𝑓 − 𝑁𝑓 relationship appeared to better fit the fatigue data of the experimental materials as compared to the 𝜀𝑎 − 𝑁𝑓 relationship and contributed to a reduction in data scatter.

null

['Alkunte, Suhas', 'Rajeshirke, Mithila', 'Huseynov, Orkhan', 'Fidan, Ismail']

2024-03-25T22:12:46Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124315', 'https://doi.org/10.26153/tsw/50923']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['fatigue life', 'fatigue prediction', "Basquin's Model", 'S-N curve', 'FGAM']

Fatigue Life Prediction of Functionally Graded TPU and PLA Components Produced by Material Extrusion

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f39fb836-c0f7-432b-b6c9-1e37ae7a7fc5/download

University of Texas at Austin

The objective of the present research is to examine the fatigue life estimation of functionally graded additive manufacturing (FGAM) components produced by the Material Extrusion (MEX). Current research studies demonstrate the potential of functionally graded materials (FGMs) in enhancing the mechanical properties of engineered structures. The raw materials employed for the experimentation of this study are a combination of Polylactic acid (PLA) and Thermoplastic Polyurethane (TPU). To predict fatigue life, several researchers have utilized various statistical approaches. In this investigation, an experimental study is conducted utilizing Tension-Tension (T-T) loading conditions and different stress levels (80, 60, 40, and 20% of Ultimate tensile strength), followed by the application of Basquin’s Model for fatigue life prediction. The results obtained indicate that the model may be utilized to predict fatigue response. Overall, the soft-hard material combinations with adaptable properties produced through FGAM have potential applications in dental and orthopedic fields.

null

['Maskery, I.', 'Aboulkhair, N.T.', 'Tuck, C.', 'Wildman, R.D.', 'Ashcroft, I.A.', 'Everitt, N.M.', 'Hague, R.J.M.']

2021-10-21T15:31:05Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89397

eng

2015 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', 'aluminum alloy', 'AlSi10Mg', 'stress-strain', 'fatigue performance']

Fatigue Performance Enhancement of Selectively Laser Melted Aluminum Alloy by Heat Treatment

Conference paper

https://repositories.lib.utexas.edu//bitstreams/60d145ef-ca57-44b9-a051-7e5031161e7c/download

University of Texas at Austin

We measured the stress-strain behaviour and fatigue performance of the aluminium alloy Al-Si10-Mg manufactured by selective laser melting (SLM). This process, specifically the rapid cooling of the metal from its molten state, results in a fine microstructure, generally providing high hardness but poor ductility. We used a heat treatment to alter the microstructure of the material from its as-built state. This significantly improved the ductility and fatigue performance. The elongation at break for the heat treated material was nearly three times greater than that observed for the as-built material, and the fatigue strength at 106 cycles was around 1.6 times as high. Combined with the design freedoms of additive manufacture, this development increases the suitability of lightweight SLM parts for use in the aerospace and automotive sectors, where good fatigue performance is essential.

null

['Beard, William', 'Lancaster, Robert', 'Adams, Jack', 'Buller, Dane']

2021-11-30T21:02:08Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90547', 'http://dx.doi.org/10.26153/tsw/17466']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'laser powder bed fusion', 'stainless steel 316L', 'low cycle fatigue']

Fatigue Performance of Additively Manufactured Stainless Steel 316L for Nuclear Applications

Conference paper

https://repositories.lib.utexas.edu//bitstreams/cf0efc07-11af-49f6-ae85-5d40e7edfdf8/download

University of Texas at Austin

Additive manufacturing (AM) is a rapidly growing technology which is extending its influence into many industrial sectors such as aerospace, automotive and marine. Recently the nuclear sector has considered AM in the production of nuclear reactor components due to its possible advantages over conventional manufacturing routes. This includes considerable cost savings due to less material wastage, the ability to produce complex near net shape components that conventional manufacturing processes are unable to achieve and a reduced manufacturing time. Initially, Stainless Steel 316L (SS316L) manufactured by laser powder bed fusion (LPBF) has been identified as a potential candidate. However, due to the transient nature of the microstructure it is now of fundamental importance to assess and understand the mechanical behaviour of the LPBF material. This paper will highlight some of the recent research at Swansea University in investigating the variation on the fatigue characteristics between wrought SS316L and LPBF processed SS316L material. This will include an extensive microstructural and fractographic investigation. As LPBF material looks to replace conventionally manufactured equivalents, an understanding of how build integrity and orientation affects the mechanical properties of AM material is critical. Wrought and vertical LPBF material are to be assessed to understand how the microstructure controls the fatigue performance of LPBF SS316L material.

null

['Raju, Nandhini', 'Rosen, David W.']

2021-12-06T21:56:06Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90687', 'http://dx.doi.org/10.26153/tsw/17606']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['maraging steel', 'fatigue properties', 'powder bed fusion', '3D printing']

Fatigue Properties of 3D Printed Maraging Steel

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3475c52c-f599-473b-b3cf-da9f056abce5/download

University of Texas at Austin

The objective of this paper is to investigate fatigue properties of maraging steel, in the fabricated, machined, and heat-treated conditions, printed by powder bed fusion. Samples were manufactured in an EOS M280 machine in the X and Z build directions. Manufactured samples were tested under four different conditions: fabricated, machined, heat-treated, and heat-treated and machined. Each condition was expected to have different fatigue properties. The maximum stress and number of cycles to failure results were compared to understand the influence of the different build orientations and conditions on fatigue properties and limits. Results showed that machining and heat treatment, individually and together, had significant effects on fatigue properties. Additionally, the selection of standards, selection of sample counts, and statistical analysis of results will be discussed along with the maraging steel fatigue properties.

null

['Nandi, Indrajit', 'Welsh, Jade', 'Simsiriwong, Jutima', 'Shao, Shuai', 'Shamsaei, Nima']

2023-01-25T14:18:50Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117288', 'http://dx.doi.org/10.26153/tsw/44169']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Murakami’s model', 'Laser powder bed fusion', 'Very high cycle fatigue', '17-4 precipitation hardened stainless steel']

Fatigue strength prediction through defects-based analysis of L-PBF 17-4 PH stainless steel

Conference paper

https://repositories.lib.utexas.edu//bitstreams/dae40d16-6c9d-4a73-8c23-cf0c3569c096/download

null

Murakami’s approach has been used in the high cycle fatigue regime to relate the fatigue limit to the critical defect size and location in additively manufactured (AM) metallic materials. However, the applicability of this model has not yet been thoroughly examined for AM materials in the very high cycle fatigue (VHCF) regime. Therefore, this study investigates the possibility of relating the volumetric defect features to the fatigue strength of 17-4 precipitation hardened (PH) stainless steel (SS) manufactured via laser-powder bed fusion (L-PBF) additive manufacturing technology. The 17-4 PH SS specimens are manufactured using an EOS M290 L-PBF system, heat-treated, machined, polished, and tested in the VHCF regime using an ultrasonic fatigue testing system. Careful fractography has also been performed on all fractured specimens to determine the volumetric defects responsible for the crack initiation.

null

['Blake, Paul', 'Fodran, Eric', 'Koch, Martin', 'Menon, Unny', 'Priedeman, Bill', 'Sharp, Stephen']

2018-11-29T20:48:37Z

1997

Mechanical Engineering

doi:10.15781/T20863R44

http://hdl.handle.net/2152/70342

eng

1997 International Solid Freeform Fabrication Symposium

Open

['CAD/CAM', 'Acrylinitrile']

FDM of ABS Patterns for Investment Casting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/886b8233-e841-48a3-b9f8-fe82042fc79e/download

null

This paper will evaluate the suitability offused deposition modeling (FDM) of acrylonitrile butadiene styrene (ABS) patterns for use in investment casting. The focus is on integration with existing foundry practices. It is a combined industry/university project with the case studies performed at the industrial sites with university produced patterns. Process parameters, ash handling and casting issues are addressed.

null

['Tyberg, Justin', 'Bohn, Jan HeIge']

2019-02-22T20:07:12Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73472', 'http://dx.doi.org/10.26153/tsw/622']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['slicing techniques', 'smooth-surface']

FDM Systems and Local Adaptive Slicing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7d59c69e-76f9-435e-933a-2cca3358d330/download

null

['Comb, James', 'Priedeman, William', 'Turley, Patrick W.']

2018-09-26T19:33:12Z

1994

Mechanical Engineering

doi:10.15781/T25X25Z09

http://hdl.handle.net/2152/68588

eng

1994 International Solid Freeform Fabrication Symposium

Open

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

FDM® Technology Process Improvements

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e34f58b0-2a7e-44b8-b992-6fc940ea3081/download

null

Since the introduction ofrapid prototyping technology as a tool for time compression and concurrent engineering in the design and manufacturing process, many enhancements and refinements have been made based on the experience of users and manufacturers of rapid prototyping equipment. These improvements contribute significantly to faster production of quality output from rapid prototyping systems. There are diverse control and material selection parameters that affect prototype models built using the Fused Deposition Modeling (FDM®) process. This paper reviews the role of several of these parameters in the process. Data will be presented to help the user choose the appropriate material for specific applications including density, tensile modulus, flexural modulus, tensile strength, flexural strength, impact strength, and hardness. The integration of material, hardware, and software in the FDM technology begins with the understanding of the basic requirements ofthe machine and ends with an operating procedure to choose the parameters for optimal model output and efficiency. Some of the variables include: part geometry, deposition geometry, deposition speed, liquefier temperature, material, flow control parameters, etc. Designed experiments are used in material formulation through modeling parameter defmition activities

null

['Reiher, Thomas', 'Koch, Rainer']

2021-10-21T16:55:13Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89404

eng

2015 International Solid Freeform Fabrication Symposium

Open

['Additive Manufacturing', 'FE-optimization', 'topology optimization', 'structural parts']

FE-Optimization and Data Handling for Additive Manufacturing of Structural Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f27cb4cd-8ada-4415-ac2c-815bb07d4110/download

University of Texas at Austin

Additive Manufacturing (AM) offers high potential due to its freedom of design for structural parts. Especially in combination with FE-based topology optimization an optimal use of material and thus significant weight reductions can be expected. However, the application of AM is hampered by different additional manufacturing processes along the entire production chain and data handling induced restrictions. Disadvantages emerge from a lack of adjustment of the entire design process for AM. First the optimization algorithms are not targeted to the opportunities and restrictions of AM – represented by design rules – like the design of support structures. Secondly, the CAD software is not adjusted to AM in particular. Creating freeform shaped surfaces based on the optimization results is significantly less convenient than building defined blocks or turning parts following the needs of conventional machining. The indispensable subsequent interpretation of optimization results regarding the design rules and the possibilities of CAD-tools counteracts optimal results. This paper considers different approaches for a Topology Optimization (TO)-shape regaining on different sample parts including telecommunication satellite parts. An innovative design methodology is presented getting crucial for creating high quality designs.

null

['Masuo, Christopher', 'Nycz, Andrzej', 'Noakes, Mark W.', 'Vaughan, Derek', 'Sridharan, Niyanth']

2021-11-18T01:09:58Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90385', 'http://dx.doi.org/10.26153/tsw/17306']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['wire arc additive manufacturing', 'maraging steel', 'high-strength tooling', 'feasibility', 'single bead welds', 'metal big area additive manufacturing', 'mBAAM']

Feasibility Analysis of Utilizing Maraging Steel in a Wire Arc Additive Process for High-Strength Tooling Applications

Conference paper

https://repositories.lib.utexas.edu//bitstreams/61b79a38-98c1-429c-92f3-4c42b5ed1443/download

University of Texas at Austin

Traditional tool and die development require skilled labor, long lead time, and is highly expensive to produce. Metal Big Area Additive Manufacturing (mBAAM) is a wire-arc additive process that utilizes a metal inert gas (MIG) welding robot to print large-scale parts layer-by-layer. By using mBAAM, tooling can be manufactured rapidly with low costs. For cold work tooling applications, a high hardness level is desired to increase the life-time of the tool. A promising material that can achieve this is maraging steel. Maraging steel is known to have good weldability; however, further testing must be conducted to ensure it is feasible for printing using mBAAM. In this paper, initial process parameters were obtained by printing single bead welds. Multi-bead walls were then printed with some refinement of process parameters to construct homogenous outer features of the walls. Lastly, the walls were heat-treated, and hardness data was gathered through Rockwell Hardness tests.

null

['Wu, Guohua', 'Langrana, Noshir', 'Rangarajan, Sriram', 'Sadangi, Rajendra', 'Safari, Amhad', 'Danforth, Stephen C.']

2019-02-26T16:56:37Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73486', 'http://dx.doi.org/10.26153/tsw/636']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['Rapid Prototyping', 'RTV mold']

Feasibility of Fabricating Metal Parts from 17-4PH Stainless Steel Powder

Conference paper

https://repositories.lib.utexas.edu//bitstreams/96e22285-2ffc-4ad6-a985-84046e9907b4/download

null

17-4 PH stainless steel is known to provide an attractive combination of high strength and corrosion resistance. In this research, the feasibility of SFF fabrication of high density parts using PH powder is examined. A part can be fabricated using both indirect and direct methods. The indirect method includes making a negative RTV mold, making compounded material using ECG binder and stearic acid with the metal powder, and pouring the compounded material to get a green part. This is followed by binder bum out(BBO) and sintering cycles. The direct method uses Fused Deposition of Metals(FDMet). In FDMet, the 17-4PH powder is compounded with a binder and extruded into filaments, followed by part building, BBO and sintering. The initial results of the indirect method of fabrication produced 91 % theoretical density of 17-4 PH parts with Vickers hardness of 223

null

['Jonckers, D.', 'Tauscher, O.', 'Stoll, E.', 'Thakur, A.']

2021-12-07T18:12:33Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90744', 'http://dx.doi.org/10.26153/tsw/17663']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['feasibility', 'on-orbit additive manufacturing', 'large-scale freeforming', '3D printing']

Feasibility Study of Large-Format, Freeform 3D Printing for On-Orbit Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b3cf0d04-1cce-4f05-9126-d302b3e441a7/download

University of Texas at Austin

Large scale, on-orbit additive manufacturing (AM) and assembly is being considered as a modular and resource saving approach to facilitate permanent human presence in space. To realise this, a novel AM approach to freeform fabricate large, functional structures in space has been developed. Combining the reach of a free-flying CubeSat with a collaborative robotic arm and a 3D printer, large support-free thermoplastic structures can be manufactured beyond the size of the setup itself. The feasibility of the proposed fabrication approach was established using the Experimental Lab for Proximity Operations and Space Situational Awareness (ELISSA) system, where a modified fused filament fabrication setup was mounted on a free-flyer to 3D print free-standing structures. Using a continuous navigation path incorporating an infinite fabrication loop, over 70 centimetre long, support-free trusses were produced to well demonstrate the potential of the proposed method in boundless direct printing of complex structures, independent of gravity or printing orientation.

null

['Yamagata, Y.', 'Sagawa, T.', 'Nitawaki, M.', 'Abe, T.']

2023-04-03T17:39:49Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117726', 'http://dx.doi.org/10.26153/tsw/44605']

eng

2022 International Solid Freeform Fabrication Symposium

Open

Additive manufacturing

Feasibility Study of Large-Sized Aluminum Facades by Using Wire Arc Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1015a1a7-9e25-45b8-9d85-7bb15b26866f/download

null

Over the past few years, there has been growing interest in the fabrication of construction components by using wire arc additive manufacturing (WAAM). We focused on the finishing materials as a potential application for WAAM and began to consider fabricating aluminum building facades. However, there are several issues, such as fabrication size of 4-5m, aesthetics, and structural performance. Therefore, a trial fabrication and a non- destructive static loading test were conducted. In the study, an aluminum chair was used as a model because it contains the engineering basis of the building facades. In the trial fabrication, a method of leveling the build surface for each of the multiple layers was found to be effective for large-sized fabrication. Bead blasting was also effective in removing oxides from aluminum surfaces and adjusting the appearance. In the loading test, both displacement and strain measurements agreed well with the FEM analytical values. The results showed that WAAM has the possibility of fabricating large-sized aluminum building facades with the structural performance expected in the FEM analysis.

null

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

2021-10-21T20:34:37Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89440

eng

2015 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'medium scale projection', 'network production', 'flexible manufacturing systems']

Feasibility Study of Small Scale Production Based on Additive Manufacturing Technologies

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b10e15b1-f590-476a-8191-ceeabc039d81/download

University of Texas at Austin

Along the last years, the complexity of products has been growing progressively, while the product development life-cycle tended to be reduced. In addition to that, additive manufacturing technologies increased their role in the product development process, resulting in reduction of errors and products release time. In spite of these benefits, the main application of these technologies is still focused on initial phases of projects and results in high costs of parts and low volumes. On the other hand, although conventional productivity processes results in low costs and high volumes, the investment related to these processes are high and the implementation time are long. For that reason, the main goal of this work is to investigate the possibility of application of additive manufacturing technologies for small and medium scale production. Along this work, the main direct and indirect processes which are used for small and medium scale production were studied and a numerical cost model were developed for each one. In order to compare the benefits and disadvantages among the processes, 3 parts were selected and analysed through such models. By the end, the main cost, payback; amortization and takt time were identified and the most suitable process was found in accordance with annual part demand.

null

['Niino, Toshiki', 'Haraguchi, Hisashi', 'Itagaki, Yutaro']

2021-10-04T20:14:18Z

8/17/11

Mechanical Engineering

null

['https://hdl.handle.net/2152/88335', 'http://dx.doi.org/10.26153/tsw/15274']

eng

2011 International Solid Freeform Fabrication Symposium

Open

['plastic laser sintering', 'powder bed heating', 'powder bed preheating', 'energy consumption']

Feasibility Study on Plastic Laser Sintering without Powder Bed Preheating

Conference paper

https://repositories.lib.utexas.edu//bitstreams/13320ce2-98ac-43c6-8149-48d73e04d9e4/download

University of Texas at Austin

In a plastic laser sintering machine, the most part of power consumption is spent on heating of powder bed. The powder bed heating is essential to prevent parts from warping during the process. However metal laser melting is normally performed without such heating. During the process, warping is suppressed by fixing the parts to a base plate. In the present research, the same scheme was introduced to plastic laser sintering. A plate of 2mm was successfully obtained. Residual stress was completely relieved by annealing treatment of 30min and permanent deformation was negligible. A relative density of 90%, which is standard level of commercially available part, was obtained. Tensile and impact strength were limited to 1/2 and 2/3 of those obtained by normal process, respectively. Energy consumption of laser module in preheating free process is around 45MJ/kg, and complete robustness against power supply interruption was demonstrated.

null

['Tata, Kamesh', 'Fadel, Georges']

2018-11-16T16:22:39Z

1996

Mechanical Engineering

doi:10.15781/T2959CT47

http://hdl.handle.net/2152/70294

eng

1996 International Solid Freeform Fabrication Symposium

Open

['3D systems', 'STL model representation', 'CAD']

Feature Extraction From Tessellated And Sliced Data in Layered Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1c4a1164-a593-4afd-b38e-ce96111610a4/download

null

When parts are built in layers, the cross sectional area of each layer has to be defined and filled with a pattern of vectors. This filling process is called hatching and the vectors defme the hatch pattern. To accurately reproduce a three dimensional object, key features need to be identified. In particular, top and bottom surfaces, edges. holes and protrusions must be recognized to ensure the slice plane does carry-the critical information required for the build. This paper describes a technique to extract relevant features from a tessellated model to generate a correct sliced representation.

null

['Qian, Xiaoping', 'Dutta, Debasish']

2019-03-01T17:30:58Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73515', 'http://dx.doi.org/10.26153/tsw/665']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['LM', 'conductivity']

Features in Layered Manufacturing of Heterogeneous Objects

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d490a248-d8b7-4fe4-9e39-6fe7f262caf4/download

null

The usage of features in computer aided design and manufacturing has increased significantly over the last decade. By and large, all such features are geometric (form features). In this paper, we shall discuss the need to go beyond current geometric features and consider material -- composition, and gradation -- within the object. This need has been brought about by layered manufacturing technologies which build up parts, layer by layer, under computer control. While industrial use of this new technology has been for making prototypes, functional metallic parts can/are being made by layered manufacturing. Furthermore, a variety of materials can be deposited to create multi-material and functionally graded components. We consider features in this new domain (of layered manufacturing) and identify research topics and present an overview of our current focus on "material features" in the context of heterogeneous solid models.

null

['Abdelrarhman, Mostafa', 'Starr, Thomas L.']

2021-10-20T20:23:35Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89353

eng

2015 International Solid Freeform Fabrication Symposium

Open

['polymer laser sintering', 'feed-forward control', 'part geometry', 'temperature history']

Feedforward Control for Polymer Laser Sintering Process Using Part Geometry

Conference paper

https://repositories.lib.utexas.edu//bitstreams/19f38e5b-64f6-445d-9e30-42fbd05b62cc/download

University of Texas at Austin

For the polymer laser sintering process, achieving optimum mechanical properties requires that every volume element of a part experience a temperature history sufficient to reach full density. This history must include a peak temperature high enough to fully melt, but not degrade, the polymer and a cool-down period that ensures elimination of porosity, interlayer bonding and relaxation of stress. Real-time thermal monitoring of the laser sintering process has shown that this temperature history depends on the geometries of both the current and prior layers. In this paper we demonstrate a feed-forward control system that improves uniformity of the temperature history for parts with variable cross-sections. The control algorithm for this system will utilize information from layerwise geometry models for parts in a multi-part build. The cross-sectional area for every layer will be used at run-time for feed forward control the laser scan parameters. The results confirmed maintaining constant peak temperature throughout the part. This control system ensures optimized sintering for parts with complex geometries.

null

O'Reilly, Sean B.

2018-05-03T18:34:09Z

1993

Mechanical Engineering

doi:10.15781/T2PV6BQ73

http://hdl.handle.net/2152/65055

eng

1993 International Solid Freeform Fabrication Symposium

Open

['FFF lab', 'Alpha Manufacturing Development Center', '3D Solid Model', 'stereolithography']

FFF at Ford Motor Company

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ac3c8f59-cc5a-4831-815e-cccad71f56e2/download

null

Ford's effort in Free Fonn Fabrication (FFF) began in 1987 with the fontation of an internal consortium, Calp)sed of a dozen different activities, whose purpose was to evaluate and apply, where possible, this errerging tecl:mology. Each of the consortium members agreed to contribute sare rroney and, rrore irrportantly, one or rrore people to work on this project. By the following year (1988) the first rrachine, an SLA-1, had been installed at the Alpha Msmufacturing Develq:ment Center and fomed the cornerstone of the FFF Lab.

null

['Xia, B.', 'Saari, M.', 'Cox, B.', 'Richer, E.', 'Krueger, P.S.', 'Cohen, A.L.']

2021-10-28T19:35:20Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89678

eng

2016 International Solid Freeform Fabrication Symposium

Open

['Fiber Encapsulation Additive Manufacturing', 'electrical junctions', 'material fabrication']

Fiber Encapsulation Additive Manufacturing: Materials for Electrical Junction Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/de90e005-8c70-4da9-a523-c8bfb1c189cd/download

University of Texas at Austin

Fiber Encapsulation Additive Manufacturing (FEAM) is a novel 3-D printing process that permits the printing of electromechanical and electronic devices within a single, affordable machine. A key challenge of FEAM is creating robust and reliable electrical junctions between encapsulated wires, enabling more complex devices and circuits to be fabricated. We present current efforts to explore and characterize several different methods for creating junctions: solder, solder paste, and a custom-formulated electrically conductive polymer composite. All three methods are analyzed in terms of printability, material compatibility, repeatability, and performance.

null

['Wang, Xin', 'Tian, Xiaoyong', 'Li, Dichen']

2021-11-15T22:14:32Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90290', 'http://dx.doi.org/10.26153/tsw/17211']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['metal matrix composite', '3D printing', 'additive manufacturing']

Fiber Traction Printing--A Novel Additive Manufacturing Process of Continuous Fiber Reinforced Metal Matrix Composite

Conference paper

https://repositories.lib.utexas.edu//bitstreams/55eb840c-a3d6-41ab-8fd6-1bb19116bc0a/download

University of Texas at Austin

Metal matrix composites (MMCs) are materials which have been widely used in the aerospace and automobile industries since the 1980s and have been classified as hard-to machine materials. This manuscript proposes a novel additive manufacturing process of continuous fiber reinforced metal matrix composite -- fiber traction printing (FTP). The composites with complex structures can be directly manufactured via FTP which utilizes the wetting force and capillarity force to control the flow of melting matrix. The craft is proceeding without extra pressure device and atmosphere protection device and substantially decreases the cost. This manuscript introduces the proof-of-concept prototype and the ability to control the flow of melting matrix and fiber distribution through this process yields a flexible manufacturing route to fabricating 3D metal matrix composite parts with full density and complex geometries.

null

['Hostetler, John M.', 'Goldstein, Jonathan T.', 'Bristow, Douglas', 'Landers, Robert', 'Kinzel, Edward C.']

2021-11-04T14:18:14Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89967

eng

2017 International Solid Freeform Fabrication Symposium

Open

['glass fiber', 'transparent glass', 'fiber-fed process', 'laser-heated process', '3D printing', 'additive manufacturing']

Fiber-Fed Laser-Heated Process for Printing Transparent Glass

Conference paper

https://repositories.lib.utexas.edu//bitstreams/51fe27f9-7d60-4bb4-b79c-6f368016c9d2/download

University of Texas at Austin

This paper presents the Additive Manufacturing (AM) of glass using a fiber-fed process. Glass fiber with a diameter of 100 μm is fed into a laser generated melt pool. A CO2 laser beam is focused on the intersection between the fiber and the work piece which is positioned on a four-axis computer controlled stage. The laser energy at λ=10.6 μm is directly absorbed by the silica and locally heats the glass above the working point. By carefully controlling the laser power, scan speed, and feed rate, bubble free shapes can be deposited including trusses and basic lenses. Issues unique to the process are discussed, including the thermal breakdown of the glass, buckling of the fiber against an inadequately heated stiff molten region, and dimensional control when depositing viscous material.

null

['Hostetler, John M.', 'Johnson, Jason E.', 'Goldstein, Jonathan T.', 'Bristow, Douglas', 'Landers, Robert', 'Kinzel, Edward C.']

2021-11-10T21:25:06Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90180', 'http://dx.doi.org/10.26153/tsw/17101']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['glass fiber', 'glass structure', 'printing', 'additive manufacturing']

Fiber-Fed Printing of Free-Form Free-Standing Glass Structures

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b7419e91-76f3-4873-9de9-cff9bcf2332b/download

University of Texas at Austin

Additive Manufacturing (AM) of low-profile 2.5D glass structures has been demonstrated using a fiber-fed laser-heated process. In this process, glass fibers with diameters 90-125 µm are supported as they are fed into the intersection of the workpiece and a CO2 laser beam. The workpiece is positioned by a four-axis CNC stage with coordinated rotational/transitional kinematics. The laser energy at λ = 10.6 µm is coupled to phonon modes in the glass, locally heating it above its working point. The rapid heating and cooling process allows for the deposition of various glasses into free-standing three-dimensional structures such as trusses and other complex geometries. Issues unique to the process are discussed, including the thermal breakdown of the glass and index inhomogeneity between the fiber core and cladding when using single-mode optical fiber feedstock.

null

['Angenoorth, J.', 'Rumschottel, D.', 'Leitner, B.', 'Schumm, V.', 'Ettemeyer, F.', 'Unsal, I.', 'Gunther, D.']

2024-03-27T03:14:06Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124459', 'https://doi.org/10.26153/tsw/51067']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['reinforced sand', 'binder jetting', '3D printing', 'additive manufacturing']

Fiber-Reinforcement of Binder-Jetted Casting Molds for Multiple Usag

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d5923ff4-5302-4e91-b033-c990c0ef22f1/download

University of Texas at Austin

Widely used sand casting with lost molds is an efficient and cost-effective way of producing geometrically complex components. As the demand for sand has tripled over the last two decades, finding new solutions for thermostable binder systems and ensuring the efficient use of resources is essential. To address this issue, the REINFORCED SAND project is exploring glass fiber-reinforced sand molds and temperature-stable inorganic binders within the binder-jetting process. The aim is to improve the mechanical properties of the D-printed casting molds to make multiple uses of these possible, reducing resource consumption and increasing profitability. For this purpose, various material systems and manufacturing parameters were examined. It has been demonstrated that fiber-reinforced sand molds can be used for multiple castings, and fibers can be principally processed in the binder jetting process. These efforts aim to make sand casting production more environmentally friendly and sustainable. The REINFORCED SAND project is a step towards achieving these goals.

null

['Chesser, Phillip C.', 'Post, Brian K.', 'Roschli, Alex', 'Lind, Randall F.', 'Boulger, Alex M.', 'Love, Lonnie J.', 'Gaul, Katherine T.']

2021-11-15T21:27:50Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90279', 'http://dx.doi.org/10.26153/tsw/17200']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['fieldable platform', 'concrete structure', 'large-scale deposition', 'sky big area additive manufacturing', 'SkyBAAM']

Fieldable Platform for Large-Scale Deposition of Concrete Structures

Conference paper

https://repositories.lib.utexas.edu//bitstreams/60b25c19-7f43-4dd1-a8fb-027c072fd44f/download

University of Texas at Austin

Oak Ridge National Laboratory’s Manufacturing Demonstration Facility is developing a novel, large-scale additive manufacturing, or 3D printing, system. The Sky Big Area Additive Manufacturing (SkyBAAM) system will ultimately be a fieldable concrete deposition machine with pick and place abilities that will allow for full-scale, automated construction of buildings. The system will be implemented with existing construction equipment meaning conventional cranes will be used to suspend the print head. SkyBAAM will be cable-driven by four base stations and suspended from a single crane. The elimination of a gantry system, found commonly in large-scale additive manufacturing systems, will enable SkyBAAM to be quickly set up with minimal site preparation. The medium-scale version of SkyBAAM is currently in development. The system design, cable stiffness analysis, and tactics for freezing rotational degrees-of-freedom (DOF), detailed in this paper, will provide a basis for the final, large-scale version of the SkyBAAM system.

null

['Agarwala, M.K.', 'Weeren, R. van', 'Bandyopadhyay, A.', 'Safari, A.', 'Danforth, S.C.', 'Priedeman, W.R.']

2018-11-15T20:31:27Z

1996

Mechanical Engineering

doi:10.15781/T2GX45D8J

http://hdl.handle.net/2152/70277

eng

1996 International Solid Freeform Fabrication Symposium

Open

['SFF', 'powder systems', 'binder chemistry']

Filament Feed Materials for Fused Deposition Processing of Ceramics and Metals

Conference paper

https://repositories.lib.utexas.edu//bitstreams/37e144f9-ec03-41ee-a0e8-ba8e2dd28403/download

null

Fused Deposition of Ceramics (FDC) and Metals (FDMet) are SFF techniques, based on commercial FDMTM technology, for fabrication of ceramic and metal components. The FD processes use feed material in the form of filaments which require certain phy~ical and mechanical properties. FDC and FDMet processes employ fila.n::ents formed from ?erannc ~r metal powders mixed with thermoplastic polymers. The thermoplastic polymers act as bmder dunng the FDC and FDMet processing in forming a green part. Development of green ceramic or metal fIlaments for FDC or FDMet processing involves three critical steps : selection of an appropriate binder chemistry, appropriate mixing procedures and fIlament fabrication techniques. This study describes the properties required for filaments for successful FD processing and the approach taken in the development of a series of binder which meets these requisite properties for a wide range of ceramics and metals. Appropriate mixing and filament forming techniques are also discussed.

null

['Mulholland, T.', 'Falke, A.', 'Rudolph, N.']

2021-10-27T22:52:06Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89639

eng

2016 International Solid Freeform Fabrication Symposium

Open

['3D printing', 'FFF', 'thermal conductivity']

Filled Thermoconductive Plastics for Fused Filament Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/42bbe9eb-09b4-4b11-b151-fff760d4e86a/download

University of Texas at Austin

Although thermoplastics have traditionally been ignored as heat transfer materials, filled thermally conductive plastics fabricated in complex geometries can serve as low-cost, geometrically complicated heat exchangers, along with other thermal applications such as heat sinks. Thermally conductive, 3D printed heat exchangers can have a significant impact on power generation technology at many scales, with advantages in allowing distributed, on-site manufacturing on multiple, independent machines, and the virtual elimination of scrap. This can command significant cost savings compared to traditional, machined metal heat exchangers. This work examines compounds of polyamide 6 with copper fiber and sphere fillers produced in a corotating twin screw extruder. The thermal conductivity is measured and related to the filler content, shape, and orientation.

null

['Jariwala, Amit S.', 'Ding, Fei', 'Zhao, Xiayun', 'Rosen, David W.']

2020-03-11T15:10:39Z

9/10/08

Mechanical Engineering

null

['https://hdl.handle.net/2152/80247', 'http://dx.doi.org/10.26153/tsw/7266']

eng

2008 International Solid Freeform Fabrication Symposium

Open

['Mask Projection Micro-Stereolithography', 'MPµSLA']

A Film Fabrication Process on Transparent Substrate using Mask Projection Micro-Stereolithography

Conference paper

https://repositories.lib.utexas.edu//bitstreams/85303b7b-1ba1-490b-8b94-93d944490617/download

null

In this study, a Mask Projection Micro-Stereolithography (MPµSLA) process with the ability to cure a film of various thicknesses on transparent substrates is presented. Incident radiation, patterned by a dynamic mask, passes through a transparent substrate to cure photopolymer resin layers that grow progressively from the substrate surface. When compared to existing Stereolithography techniques, this technique eliminates the necessity of recoating, reducing process time and improving accuracy. A film of varying thicknesses can be fabricated on flat or curved transparent substrates. Models of the optical system and resin cure are developed and reported. An existing MPµSLA process planning method is being extended to account for radiation transmission through a substrate. The models are verified using experiments.

null

['Fischer, M.', 'Schöppner, V.']

2021-10-18T20:32:46Z

2014

Mechanical Engineering

null

https://hdl.handle.net/2152/89236

eng

2014 International Solid Freeform Fabrication Symposium

Open

['Fused Deposition Modeling', 'ABS-M30', 'mass finishing', 'dimensional accuracy']

Finishing of ABS-M30 Parts Manufactured with Fused Deposition Modeling with Focus on Dimensional Accuracy

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c5eacedd-961c-45c3-9fd7-4df85790cb77/download

University of Texas at Austin

Fused Deposition Modeling (FDM) parts are prone to process-related rough and wavy surfaces with stair-stepping effects whenever the parts produced have sloped or rounded geometries. These stair-stepping effects can be reduced by using a smaller slice height, but complete elimination is not possible. In this paper, FDM parts manufactured with the material ABS-M30 are finished using mass finishing methods. The mass finishing is done with a trough vibrator, which is comparatively gentle to the parts in comparison to other mass finishing technologies. The analysis discusses the surface-smoothing effect of finishing time and intensity on various part sizes and build orientations. In addition, the dimensional accuracy of the parts after the finishing process is examined.

null

['Wang, Xuanping', 'Li, Shichong', 'Fu, Youzhi', 'Gao, Hang']

2021-11-01T22:55:10Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89791

eng

2016 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'abrasive flow machining', 'polishing', 'complex structure']

Finishing of Additively Manufactured Metal Parts by Abrasive Flow Machining

Conference paper

https://repositories.lib.utexas.edu//bitstreams/dc9c15f4-a8a8-44dd-971b-447020456161/download

University of Texas at Austin

Surface finishing is still a crucial challenge in metal Additive Manufacturing (AM) as the as-built surface roughness is difficult to fulfill service requirements, due to staircase effect, balling effect inherent to AM. Abrasive flow machining (AFM) is a non-conventional finishing technique that offers better accuracy and efficiency for parts with difficult-to-access structures, and the application of AFM to finishing metal parts of AM process is discussed in this paper. The aluminum and titanium grilles by selective laser melting are taken to explore the finishing effect of outer and inner surfaces. The AFM process parameters of abrasive grits sizes, abrasive media viscosity, and tooling designs are optimized to implement effective material removal from the outer and inner surfaces. The results show that the AM grille parts with non-trial internal structures can be finished efficiently and consistently by AFM.

null

['Schmid, M.', 'Simon, C.', 'Levy, G.N.']

2021-09-28T18:07:44Z

9/15/09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88140', 'http://dx.doi.org/10.26153/tsw/15081']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['plastic part coating', 'Selective Laser Sintering', 'Rapid Manufacturing']

Finishing of SLS-Parts for Rapid Manufacturing (RM) - A Comprehensive Approach

Conference paper

https://repositories.lib.utexas.edu//bitstreams/abce9469-027d-4b12-8eb8-b572c0fbdaca/download

University of Texas at Austin

Plastic parts are often coated to fulfill the desired functional requirements during product life. This may be for decorative purposes only, but also for functions such as improved tribology, wear and humidity resistance, UV- and light stability, hygienic and biofilm resistance. Moving SLS towards Rapid Manufacturing (RM) and making those parts competitive with parts produced by other techniques (e.g. injection molding) implies the adoption of a new quality of part finishing and coating strategy for SLS. This paper provides a survey of current finishing methods used for RM-SLS parts in our institute and highlights the manually-driven process steps. The need for, and first trials with, a more automated finishing process (e.g. vibratory grinding) are discussed, as is the need for innovative supporting software tools.

null

['Reeves, P.E.', 'Cobb, R.C']

2018-10-05T16:45:43Z

1995

Mechanical Engineering

doi:10.15781/T27W67R07

http://hdl.handle.net/2152/68714

eng

1995 International Solid Freeform Fabrication Symposium

Open

['stereolithography', 'model geometry', 'Rapid prototyping']

The Finishing of Stereolithography Models Using Resin Based Coatings

Conference paper

https://repositories.lib.utexas.edu//bitstreams/96f427a1-82d7-4fab-b04d-c77501c691e7/download

null

The use of StereoLithography (SL) can produce accurate prototype models with complex internal and external features. However, a major problem to commercial use is the poor surface finish caused mainly by 'stair stepping' which is inherent in layer manufacturing. Models are often finished by hand but this is labour intensive, highly selective and causes inaccuracies in the model geometry. A three-year research project has been undertaken to address these issues and to investigate a range of surface coatings and mechanical finishing processes applied to SL models. This paper describes some initial findings using resin coatings applied to both cured and uncured SL parts.Initial findings suggest that excess resin retained after part stripping can result in a lower surface roughness than parts thoroughly cleaned prior to post curing.Through the addition of photocurable and epoxy based resins to parts in both the un-cured, green and cured states, surface roughness has been seen to be reduced by up to 50% on complex parts.

null

['Hague, Richard', 'Dickens, Phill']

2018-11-16T15:13:19Z

1996

Mechanical Engineering

doi:10.15781/T2FX74J0W

http://hdl.handle.net/2152/70285

eng

1996 International Solid Freeform Fabrication Symposium

Open

['SL models', 'Quickcast', 'autoclaving']

Finite Element Analysis and Strain Gauging of the Stereolithography/Investment Casting System

Conference paper

https://repositories.lib.utexas.edu//bitstreams/fe26733f-841c-441a-958e-d15cc416f93e/download

null

Many metal parts have been produced from stereolithography (SL) models via the investment casting route. However, it is still not possible for every foundry to directly use SL models as thermally expendable patterns and gain the same success as achieved with wax patterns. Significant drawbacks still exist with the QuickCastTM structure that restricts its use to specialist investment casting foundries who are willing to alter their standard techniques. As part of a continuing work programme at the University ofNottingham, the stresses that are created in the SL/ceramic construction have been determined using simple stress analysis and finite element analysis techniques. Further work has involved connecting strain gauges and thermocouples to SL parts in order to confirm the results obtained with the theoretical stress analysis. Inspection of the results obtained is aiding the generation of new build structures to enable the successful autoclaving of SL models. Details ofthe work to date are outlined in this paper, along with the results obtained.

null

['Dalgarno, K.W.', 'Childs, T.R.C.', 'Rowntree, I.', 'Rothwell, L.']

2018-11-16T15:54:43Z

1996

Mechanical Engineering

doi:10.15781/T2PG1J764

http://hdl.handle.net/2152/70291

eng

1996 International Solid Freeform Fabrication Symposium

Open

['SLS process', 'analytical procedures', 'rectangular polycarbonate']

Finite Element Analysis of Curl Development in the Selective Laser Sintering Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9d3650a1-3df4-41f9-859b-792e028def2e/download

null

The work reported within this paper is concerned with the development of analytical procedures which will allow the accuracy of parts generated by selective laser sintering to be predicted. One source of inaccuracy is curl, which results in curved part edges of flat plates manufactured lying horizontally in the part bed. This paper reports on the use of finite element techniques to model the development of curl. The models have been validated through comparison of f.e. results with the results of experimental builds, and extended to allow the influence of "bases" on the development of curl to be examined.

null

['Jiang, Wei', 'Dalgarno, K.W.']

2019-10-24T17:37:30Z

2002

Mechanical Engineering

null

['https://hdl.handle.net/2152/77403', 'http://dx.doi.org/10.26153/tsw/4492']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Deformations

Finite Element Analysis of Residual Stresses and Deformations in Direct Metal SLS Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/72ce74ae-69a8-4f14-8364-9c8b18d57b56/download

null

Direct metal SLS processes use a high power laser beam to selectively fuse fully metallic powder to directly produce functional metal components or tooling. As a thermal dynamic process, it inevitably causes thermal stresses, stress-induced deformations and cracking. Understanding these is very important in controlling residual stresses and stress-induced deformations. In this research, the residual stresses and deformations in direct laser sintering of stainless steel is investigated by an integrated thermal and mechanical model. Temperature-dependent material properties are taken into account in both models. Using a commercial finite element software, with sintered geometry and temperatures imported from a thermal model, the residual stresses and deformations of direct SLS of stainless steel are predicted. In the long term this will make it possible to achieve minimum residual stresses and deformations by controlling the SLS process parameters, material properties and other relevant parameters.

WEI JIANG gratefully acknowledge financial support from the China Scholarship Council under Grants 99821129 and National Science Foundation of China under Grants 59935110.

null

['Dai, K.', 'Crocker, J.', 'Shaw, L.', 'Marcus, H.']

2019-09-23T16:45:26Z

2000

Mechanical Engineering

null

['https://hdl.handle.net/2152/75965', 'http://dx.doi.org/10.26153/tsw/3064']

eng

2000 International Solid Freeform Fabrication Symposium

Open

Element

Finite Element Analysis of the SALDVI Process 393

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a35ff381-3585-41a6-9e6f-b910e6be98ba/download

null

Selective Area Laser Deposition Vapor Infiltration (SALDVI) is a developing solid freeform fabrication (SFF) technique aimed at the direct fabrication of ceramic and ceramic/metal structures and composites. SALDVI uses a layer-by-layer approach in which layers of powder are densified with solid material deposited from gas precursors by chemical vapor deposition (CVD) using laser heating. In this work, we have performed numerical simulation using the ANSYS code with 3-dimensional coupled field elements to calculate the temperature field and the part geometry resulting from the SALDVI process. The effects of the powder and vapor deposited material properties on the temperature distribution and the part geometry have been investigated. The result from the numerical simulation is found to be consistent with those obtained from experiments performed using the silicon carbide forming gas precursor Si(CH3)4 and SiC powder particles.

The authors gratefully acknowledge financial supports provided by the National Science Foundation under Grant No: DMI-9908249 and the Office of Naval Research under Grant No: N00014-95-1-0978.

null

['Weissman, E.M.', 'Hsu, M.B.']

2018-04-12T18:55:23Z

1991

Mechanical Engineering

doi:10.15781/T2P55F05P

http://hdl.handle.net/2152/64286

eng

1991 International Solid Freeform Fabrication Symposium

Open

['ABS powder', 'polymer powder', 'conductivity']

A Finite Element Model of Multi-Layered Laser Sintered Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a4d9b115-28b1-4d5a-8f3d-7f3636ed2cf1/download

null

Afinite element heat transfer analysis is applied to the selective laser sinteringofa layered part made frompolyroerpowder. The sinteringsubroutine in the code is based on the analyses of Scherer [l t2] and Mackenzie and Shuttleworth [3]. The density and conductivity of the particle bed are treated as functions of the void fraction of the bed. The Yagi - Kunii [4] thermal characterization of the powder bed is used to calculate the effective conductivity of the bed. An example is worked for ABS powder.

null

['Sealy, M.P.', 'Madireddy, G.', 'Li, C.', 'Guo, Y.B.']

2021-10-26T19:00:54Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89557

eng

2016 International Solid Freeform Fabrication Symposium

Open

['hybrid', 'SLM', 'laser shock peening', 'Ti64', 'residual stress']

Finite Element Modeling of Hybrid Additive Manufacturing by Laser Shock Peening

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7a33d493-9cfa-4345-8ef6-ed86fc8ce04e/download

University of Texas at Austin

Hybrid manufacturing has traditionally targeted efficiency and productivity as improvement criteria. However, the advent of additive manufacturing to print functional parts has expanded the possibilities for a hybrid approach in this field. Hybrid additive manufacturing is the combination of two or more manufacturing processes or materials that synergistically affect the quality and performance of a printed part. Hybrid additive manufacturing allows for advancements in material properties beyond efficiency and productivity. Mechanical, physical, and chemical properties can be designed and printed. The purpose of this study was to model a hybrid additive manufacturing process to investigate the resulting mechanical properties. Laser shock peening (LSP) was coupled with selective laser melting in a 2D finite element simulation in Abaqus to quantify the resulting residual stress fields. The effects of peak pressure and layer thickness were studied when coupling laser shock peening with selective laser melting.

null

['Arrieta, E.', 'Mireles, Jorge', 'Stewart, C.', 'Carrasco, C.', 'Wicker, R.']

2021-11-09T20:19:21Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90155', 'http://dx.doi.org/10.26153/tsw/17076']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['lattices structures', 'Ti-6Al-4V', 'EBM', 'FEA', 'DIC']

Finite Element Modeling of Metal Lattices Using Commercial FEA Platforms

Conference paper

https://repositories.lib.utexas.edu//bitstreams/687a4ac9-69e1-44d4-b64b-cbbdca13ac9f/download

University of Texas at Austin

The introduction of geometrical features into standard solids result in cellular materials with unique performances. The deformation mechanisms originated by the introduced geometry may not be entirely captured by the current commercial FEM software; resulting in inaccuracies in predicting the performance of cellular metals. Additionally, the inconsistency of AM material properties will result in material models with uncertainty, thus, contributing to the inaccuracy of simulations. The present work shows a process for modeling the strength of EBM Ti-6Al-4V lattices structures; starting from the definition of the convenient experiments to generate the data for the development of material models at different orientation and finalizes with the assignment of these material models to the lattice FEMs. MSC Patran/Nastran is used in this work. Experimental results of the compressive strength of lattice structures are compared with those from the FEM utilizing the different material models created from the experiments.

null

['Olleak, Alaa', 'Xi, Zhimin']

2021-11-11T16:39:13Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90241', 'http://dx.doi.org/10.26153/tsw/17162']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['finite element modeling', 'selective laser melting', 'Ti-6Al-4V', 'thermal model', 'thermo-mechanical model']

Finite Element Modeling of the Selective Laser Melting Process for Ti-6Al-4V

Conference paper

https://repositories.lib.utexas.edu//bitstreams/78ee065f-7d90-4852-a313-6f992fc18692/download

University of Texas at Austin

Physics-based modeling of the selective laser melting (SLM) process is critical for better understanding the influence of the parts quality with respect to various process parameters and scanning strategies. The challenge is to balance model validity, domain size, and computational efficiency so that the model can be practically useful for improving reliability and quality of the printed products. In this paper, a transient thermal finite element model of a SLM process for Ti-6Al-4V is developed using ANSYS for predicting the melt pool size and thermal history. The thermal solution is remapped to the structural problem to predict the induced residual stress of the products. The thermo-mechanical model is capable of handling practical domain size with reasonable computational efficiency on the process level, by developing the remeshing and remapping technique that adapts with the scanning vector.

null

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

2021-12-07T17:45:50Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90733', 'http://dx.doi.org/10.26153/tsw/17652']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['flow dynamics', 'fiber reinforced thermoplastics', 'direct deposition', 'additive manufacturing']

Finite Element Simulation of Direct Deposition Additive Manufacturing for Fiber Reinforced Thermoplastics

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f6384a95-6264-44f8-bc99-168dbebff7fd/download

University of Texas at Austin

Non-planar direct deposition additive manufacturing of polymer composites has recently seen increased attention from industries, where the molten plastics beads are extruded through a heated nozzle directly into three-dimensional space to form lightweight truss-like structures. This promising method shortens the manufacturing time and fabricates structures without stair-effect appearance that occurs in traditional layered additive manufacturing processes. This paper investigates the flow dynamics of fiber reinforced thermoplastics melt during a direct deposition process via a 2D planar deposition flow model. A quasi steady state for the deposition flow is assumed, where the flow-induced fiber orientation is evaluated through the Folgar-Tucker isotropic rotary diffusion model with the orthotropic-fitted closure approximation. The direct deposition process of a cubic lattice is simulated using finite element suite ABAQUS, where the orientation-homogenized material properties of a 13% CF-ABS are employed. Computed results indicate printing sequence affects the stress accumulation of the printed part notably.

null

['Faustini, Mario', 'Lokhande, Mahendra', 'Crawford, Richard', 'Rogers, William', 'Gitter, Andrew', 'Bosker, Gordon']

2019-10-18T15:39:17Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76242', 'http://dx.doi.org/10.26153/tsw/3331']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Prosthesis

Finite Element Structural Analysis of Prosthesis Sockets for Below-the-Knee Amputees Manufactured Using SLS

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c47a7f6e-189c-4bd1-9481-a856ac8d67b8/download

null

A very attractive application of Solid Freeform Fabrication is manufacture of prosthesis sockets for below-the-knee amputees. The custom geometric design required is very compatible with SFF techniques. The present work focuses on finite element analysis of sockets manufactured by Selective Laser Sintering using Duraform as the material. The objective is to ensure reliability of the sockets for their use by patients. This paper describes the finite element models developed for the sockets, as well as the derivation of realistic boundary conditions that may allow a simulation of the structure under regular workloads.

null

['Johnston, S.', 'Anderson, R.']

2019-10-24T18:12:30Z

2002

Mechanical Engineering

null

['https://hdl.handle.net/2152/77415', 'http://dx.doi.org/10.26153/tsw/4504']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Metal Matrix

Finite Element Thermal Analysis of Three Dimensionally Printed (3DP™) Metal Matrix Composites

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3f8e8989-652e-405f-96a9-927ff4b7aa77/download

null

Three Dimensional Printing, 3DP™, is under development for the production of metal composites through solid freeform fabrication of a skeleton, followed by sintering and then infiltration of a second, lower melting metal. To maintain dimensionality and allow for infiltration, green component sintering produces only neck growth between powder particles, which differs substantially from conventional powder metallurgy sintering practices. The objective of this study is to investigate finite element thermal-mechanical modeling in order to optimize the sinter profile and predict the final part dimension. The model will relate micro-scale thermal effects to the macro-scale by analyzing the composite medium as a meshed layered element comprising micro-scale elements. The micro-scale elements can be based on bulk transport mechanisms related to neck growth. The analytical model will eventually be used to define the thermal processing parameters and to predict optimal geometry for full density near net shape sintering and infiltration of 3DP™ manufactured components.

Financial support for this work is provided by the Office of Naval Research, Contract #N00014-C-00-0378.

null

['Doubrovski, E.L.', 'Verlinden, J.C.', 'Horvath, I.']

2021-10-06T22:33:56Z

8/18/12

Mechanical Engineering

null

['https://hdl.handle.net/2152/88461', 'http://dx.doi.org/10.26153/tsw/15398']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['Design for Additive Manufactured', 'Additive Manufacturing', 'open-ended knowledge', 'wiki environment']

First Steps Towards Collaboratively Edited Design for Additive Manufacturing Knowledge

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4776a124-b43e-4435-87ce-17bb7da2d6b1/download

University of Texas at Austin

Despite the broad coverage concerning the technological challenges, little research has been performed on the methods that enable designers to deal with Additive Manufacturing. At present, the challenge is to generate Design for Additive Manufacturing knowledge which goes beyond traditional solutions and to ensure that this knowledge is complete, correct and up to date. This paper reports on the employment of a wiki environment to support open-ended knowledge management. We applied this solution in an undergraduate prototyping course focused on exploring visual properties using AM structures. The results of the 32 students encompass unexpected designs while the knowledge on the wiki encompassed i) AM processes, ii) procedures, iii) artifacts. This forces us to rethink what should constitute DfAM.

null

['Mahale, Tushar R.', 'Taylor, James B.', 'Cormier, Denis R.']

2019-09-23T16:08:10Z

2000

Mechanical Engineering

null

['https://hdl.handle.net/2152/75951', 'http://dx.doi.org/10.26153/tsw/3050']

eng

2000 International Solid Freeform Fabrication Symposium

Open

Thermoplastic

Five-Axis Freeform Fabrication of Solid Thermoplastic Parts via SWIFT 289

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8fd06535-b40a-4bb3-bd9b-b56380c18a69/download

null

Current Rapid Prototyping (RP) & Layered Manufacturing (LM) techniques are based on controlled, precise additive manufacturing methods. These techniques suffer from problems associated with stair stepping, loss of accuracy in the z-direction due to limitations on the slice thickness and their build speeds which prevent them from being “rapid”. Proposed here, is a method, which utilizes a freeform fabrication technique, coupled with the advantages and precision of five axis machining for contoured edge generation. A new technique for the generation of solid thermoplastic parts (ABS, Polystyrene, etc) will be introduced. The proposed process will incorporate adaptive slicing for the generation of five-axis CNC code, and a sub-layer machining technique for use of uniform layer thickness will be outlined. A novel 5-axis configuration will be proposed. The proposed process will decrease, drastically, the time required for part production when compared to current commercial technologies.

null

['Lao, S.C.', 'Koo, J. H.', 'Moon, T. J.', 'Yong, W.', 'Lam, C.', 'Zhou, J.', 'Hadisujoto, B.', 'Wissler, G.', 'Pilato, L.', 'Luo, Z. P.']

2020-03-10T17:11:24Z

2008

Mechanical Engineering

null

['https://hdl.handle.net/2152/80231', 'http://dx.doi.org/10.26153/tsw/7250']

eng

2008 International Solid Freeform Fabrication Symposium

Open

rapid manufacturing

Flame Retardant Intumescent Polyamide 11 Nanocomposites – Further Study

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0bf9419c-c134-4b39-afe4-169d52928e5f/download

null

The objective of this research is to develop improved polyamide 11 and 12 polymers with enhanced flame retardancy, thermal, and mechanical properties for selective laser sintering (SLS) rapid manufacturing (RM). In the present study, a nanophase was introduced into the polyamide 11 and combine with a conventional intumescent flame retardant (FR) additive via twin screw extrusion. Arkema Rilsan® polyamide 11 molding polymer pellets were used with two types of nanoparticles such as: chemically modified montmorillonite (MMT) organoclays and carbon nanofibers (CNFs). Two types of Clariant’s Exolit® OP 1311 and 1312 intumescent FR additives were used to generate a family of FR intumescent polyamide 11 nanocomposites with anticipated synergism.

null

['Lao, S.C.', 'Koo, J.H.', 'Moon, T.J.', 'Hadisujoto, B.', 'Yong, W.', 'Pilato, L.', 'Wissler, G.']

2021-09-29T14:53:20Z

2009-09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88188', 'http://dx.doi.org/10.26153/tsw/15129']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['flammability properties', 'thermal properties', 'mechanical strength', 'polyamide 11 polymer nanocomposites', 'laser sintering', 'rapid manufacturing']

Flammability and Thermal Properties of Polyamide 11-Alumina Nanocomposites

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7197060c-acba-4cd2-a810-fe619e5ac3b5/download

University of Texas at Austin

Neat polyamides 11 and 12 lack high strength/high heat resistance and flame retardancy. The incorporation of selected nanoparticles is expected to enhance these properties to a level that is desired and required for performance driven applications. This enhancement may result in additional market opportunities for the polyamide 11 and 12 polymer manufacturers. The objective of this study is to develop polyamide 11 polymer nanocomposites with enhanced thermal, flammability, and mechanical performance for selective laser sintering (SLS) rapid manufacturing. Three types of nano-alumnia (X-0 needle, X-25SR, and X-0SR) with different organic treatments were melt-compounded into polyamide 11 in three different weight loadings of the nanoparticles (2.5%, 5%, and 7.5%). Injection molded specimens were fabricated for thermal, flammability, and mechanical properties characterization. Although nano-alumina was uniformly dispersed in polyamide 11 and better thermal stability of the nanomodified materials was observed, the desired FR characteristics of the nanomodified polyamide 11 was not achieved. None of the materials passed the desired UL 94 V0 rating.

null

['Kraft, Stefan M.', 'Lattimer, Brian Y.', 'Williams, Christopher B.']

2021-11-01T22:33:37Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89785

eng

2016 International Solid Freeform Fabrication Symposium

Open

['flammability', 'material compositions', 'object geometry', '3D printing', 'additive manufacturing']

Flammability of 3-D Printed Polymers – Composition and Geometry Factors

Conference paper

https://repositories.lib.utexas.edu//bitstreams/99fcd254-b6e3-4d7c-9848-79d0956a6ab9/download

University of Texas at Austin

The focus of this paper is to evaluate the comparative flammability of additively manufactured (AM) and conventionally molded polymers. Flammability of objects is dependent on two main factors: material composition and object geometry. To evaluate effects of material composition, experiments on polymer samples made via conventional molding and via AM were performed using an ASTM E1354 cone calorimeter to measure and compare material ignitability and heat release rate. ULTEM™ (amorphous thermoplastic polyetherimide) and PPSF/PPSU (polyphenylsulfone) heat release rates were about 10 times lower than ABS (acrylonitrile butadiene styrene). This was in part due to the large char layer formed by these materials during burning. Comparisons between conventional molded and AM materials revealed slight differences in heat release rate. Additively manufactured ABS sheets had about a 17% higher mean average heat release rate (MAHRR). Conversely, the characterization of ULTEM 9085™ sheets revealed the MAHRR of the AM samples were 13% lower than the molded samples. This is attributed to additives in the material used for extrusion AM as well as the build process itself. Effects of geometry were assessed using material cribs, which were composed of layers of rectangular prisms separated by air gaps, with prisms on consecutive layers being orthogonal. Cribs were constructed with three to ten prisms per layer to evaluate the effects of varying the internal material surface area. Below a specific threshold, the burning mass loss rate per unit area of the cribs decreased with an increase in internal material surface area; this agrees with trends predicted using a theoretical model previously developed for wood cribs.

null

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

2018-04-12T18:00:41Z

1991

Mechanical Engineering

doi:10.15781/T2ZP3WH3Q

http://hdl.handle.net/2152/64275

eng

1991 International Solid Freeform Fabrication Symposium

Open

['Rensselear Design Research Center', 'Rensselaer Polytechnic Institute', 'CAD systems', 'CSG']

A Flexible File Format for Solid Freeform Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/366f6df1-f552-4658-8860-e23e9bffd324/download

null

A flexible file format for Solid Freeform Fabrication data is presented which significantly improves on the de-facto industry standard STL format. The new format removes the redundancy present in STL files and can contain topological information. Its specification flexibility allows users to balance storage and processing costs. Since facet boundary models currently provide the greatest common denominator for data exchange between many CAD systems, they are supported by this format. Additionally, representation of CSG primitives is provided, as are capabilities to represent multiple instances of both facet and CSG solids. Format extensibility, without obsoleting existing programs, is made possible by interleaving the format schema with the data. User data can be added to existing entities, or new entities can be created. This allows the addition of NURBS based geometries in the future.

null

['Lai, Cheukfung', 'Gibson, Ian']

2019-09-23T16:03:42Z

2000

Mechanical Engineering

null

['https://hdl.handle.net/2152/75949', 'http://dx.doi.org/10.26153/tsw/3048']

eng

2000 International Solid Freeform Fabrication Symposium

Open

Prototyping

A Flexible Rapid Prototyping Cell 275

Conference paper

https://repositories.lib.utexas.edu//bitstreams/026f7a23-3117-44b4-b018-b587294abe78/download

null

Rapid prototyping systems have demonstrated high flexibility in terms of creating complex geometry parts. Improvements in accuracy and material properties enable rapid prototyping to become a widely used and important part of the product development process. Further applications and further improved performance can be achieved by combining rapid prototyping machines with conventional machine tools to form flexible manufacturing cells. One way to form such a cell is to integrate with industrial robotics. This paper will describe work carried out using an ABB IRB 1400 industrial robot in conjunction with a DTM Sinterstation 2000 to form a Flexible Rapid Prototyping Cell.

null

['Somireddy, Madhukar', 'de Moraes, Diego A.', 'Czekanski, Aleksander']

2021-11-03T20:26:20Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89923

eng

2017 International Solid Freeform Fabrication Symposium

Open

['laminates', 'flexural behavior', '3D printing', 'fused deposition modeling']

Flexural Behavior of FDM Parts: Experimental, Analytical and Numerical Study

Conference paper

https://repositories.lib.utexas.edu//bitstreams/67a320d6-1306-405a-9a5f-7340c0723e72/download

University of Texas at Austin

Fused deposition modelling (FDM) processed parts behave as composite laminate structures. Therefore, mechanics of composite laminates can be adopted for the characterization of mechanical behavior of the printed parts. In this study, the flexural properties of the 3D printed laminates are investigated experimentally, analytically and numerically. Each layer of the printed specimens is treated as an orthotropic material. The elastic moduli of a lamina are calculated by considering the mesostructure of the printed laminate in finite element simulation of tensile testing. These elastic moduli are employed in a constitutive matrix for the calculation of flexural stiffness of the laminate using classical laminate theory. Then 3-point bending tests are conducted on the printed laminates to calculate their flexural stiffness. The influence of road/ fiber size and lamina layup on the flexural properties are also investigated. Furthermore, failure phenomena of printed laminates under bending loads is investigated.

null

['Currence, Jacob', 'Morales-Ortega, Rolando', 'Steck, Jason', 'Zhou, Wenchao']

2021-11-04T14:43:44Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89973

eng

2017 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'cooperative 3D printing', 'power system', 'mobile robot']

A Floor Power Module for Cooperative 3D Printing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6aa9851e-6fd8-445c-a32b-8063cc1244a4/download

University of Texas at Austin

Cooperative 3D printing is an emerging technology that utilizes multiple printhead-carrying mobile robots to work simultaneously to 3D print or assemble products on a factory floor, which can provide the scalability, increased printing capability, and reduced human intervention for 3D printing to potentially become a mainstream digital manufacturing technology. However, powering the mobile printers for them to span entire factory floors poses an issue. Traditional cords are not an option due to restricting free movement across long distances. On-board batteries would waste energy due to additional weight and the need to recharge could interrupt ongoing print jobs and increase printing time. In this paper, we present an electrified floor to power the mobile printers wirelessly. First, we designed a floor module with stainless steel conductive strips in a concrete base and a brush that is carried by the mobile robots to make sure it never loses contact with the electrified floor while in motion. Then we designed a circuit to sort the polarity of the current from the floor based on the power requirements of the robot. A prototype of the floor power module was then developed and tested with a mobile 3D printer. Results show the developed floor power supply can power the mobile 3D printers effectively. This development will potentially enable an autonomous factory equipped with thousands of mobile 3D printers powered wireless by the factory floor.

null

['Balderrama-Armendariz, Cesar O.', 'MacDonald, Eric', 'Valadez, Esdras D.', 'Espalin, David']

2021-11-01T22:20:11Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89779

eng

2016 International Solid Freeform Fabrication Symposium

Open

['folding endurance', '3D printing', 'fusion deposition modeling']

Folding Endurance Appraisal for Thermoplastic Materials Printed in Fusion Deposition Technology

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6726b054-2481-44b1-bb7b-f3fccd88456e/download

University of Texas at Austin

The anisotropic behavior of the fusion deposition modeling (FDM) machines could change the mechanical properties of the materials in the layer by layer technology. In general, the tensile, compressive and flexural strength are decreased against molded plastics. Some lasting products need the iteration of low flexural strength and high elongation to obtain an effective flexibility to bend in repetitive movements. The present work provides an analysis of the capacity of several selected thermoplastics materials such as Nylon (PA), Polyethylene Terephthalate (PETG), Polylactide (PLA), Polyurethane (TPU) and Polypropylene (PP) in order to test the maximal load capacity and the number of folding cycles sustained in perpendicular direction of movement. Results demonstrate that those of similar to injected molded products, PP and TPU materials surpass one million of cycles in the folding test. Yet, in axial load they have lower strength against the other considered materials.

null

['Norrell, Jeffery L.', 'Wood, Kristin L.', 'Crawford, Richard H.', 'Bergman, Theodore L.']

2018-11-15T20:44:22Z

1996

Mechanical Engineering

doi:10.15781/T2C53FM56

http://hdl.handle.net/2152/70278

eng

1996 International Solid Freeform Fabrication Symposium

Open

['SLS powder beds', 'thermal behavior', 'Rapid prototyping']

Forced Convection in a Polymeric Powders

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ef939827-081a-40d0-b932-5f2092623559/download

null

In a Selective Laser Sintering (SLS) powder bed, thermal transfer occurs through multiple modes. Forced convection through the powder, or downdraft, has recently been implemented in SLS machines in an effort to enhance thermal transfer within the powder bed. In this paper, forced convection is analytically shown to be a significant thermal transfer mode for low porosities, such as seen in SLS powder beds. A polymeric powder bed subjected to downdraft is investigated with the goal of quantitatively determining thermal behavior. A numerical model describing heat transfer within a powder is presented. The design and construction of an experimental apparatus to measure the temperature profiles within a powder subjected to forced convection is described. Using the information gained in these experiments, it may be possible to better control the thermal environment of SLS powder beds, reducing growth and internal stress build-up.

null

['Crockett, Robert S.', 'Zick, Rebecca']

2019-09-23T17:22:37Z

2000

Mechanical Engineering

null

['https://hdl.handle.net/2152/75982', 'http://dx.doi.org/10.26153/tsw/3081']

eng

2000 International Solid Freeform Fabrication Symposium

Open

Fabrication

Forensic Applications of Solid Freeform Fabrication 549

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6039e524-fa20-46ac-b9bd-2c4fa1b3c3a5/download

null

Solid Freeform Fabrication was recently used to identify the dismembered body of a woman found in rural Wisconsin. Skin from the face of the victim had been removed, making visual identification impossible. A model of the skull was constructed by Laminated Object Manufacturing (LOM), using data extracted from CT scans of the victim’s head. Forensic anthropologists performed a facial reconstruction directly on the LOM model, which was then photographed and distributed. The computer model was further manipulated and served as supplemental data to investigators preparing the reconstruction. An identification from one of the distributed photographs led to the arrest of a suspect and a subsequent conviction. This is the first example that we are aware of where SFF has been used in an active criminal case, and the successful results show a promising future for SFF as a forensic tool.

We also gratefully acknowledge the financial support of the National Science Foundation and the MSOE Rapid Prototyping Consortium, as well as the facilities and expertise provided by the staff of the MSOE Rapid Prototyping Center.

null

['Tagore, G.R.N.', 'Anjikar, Swapnil D.', 'Gopal, A. Venu']

2020-03-09T14:26:59Z

2007

Mechanical Engineering

null

['https://hdl.handle.net/2152/80185', 'http://dx.doi.org/10.26153/tsw/7204']

eng

2007 International Solid Freeform Fabrication Symposium

Open

Solid Freeform Fabrication

Form Accuracy Analysis of Cylindrical Parts Produced by Rapid Prototyping

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c4d45f8a-4cb3-4ee7-bf41-d3c0bd47192b/download

null

Solid Freeform fabrication processes are being considered for creating fit and assembly nature functional parts. It is extremely important that these parts are within allowable dimensional and geometric tolerance. The part accuracy produced by rapid prototyping process is greatly affected by the relative orientation of build and face normal directions. A systematic method is needed to find the reliability of the created product. This paper discusses the work done in this area and the effect of build orientation on the part form accuracy analysis of each specified tolerance like circularity and cylindricity. Feasible build direction that can be used to satisfy those tolerances is identified. It will help process engineer in selecting a build direction that can satisfy a mathematical model of form tolerance.

null

['Sperry, M.G.', 'Carter, D.', 'Crane, N.B.', 'Nelson, T.W.']

2024-03-25T23:57:15Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124347', 'https://doi.org/10.26153/tsw/50955']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['selective doping', 'laser powder bed fusion', 'additive manufacturing']

Formation of Easy-To-Remove Supports in Laser Powder Bed Fusion through Selective Doping

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0c27e175-8846-4722-b345-b35ce6c28627/download

University of Texas at Austin

Laser Powder Bed Fusion (LPBF) is a popular Additive Manufacturing (AM) technique used c01m11only for metals. Metal paiis formed by LPBF generally require supports connecting the part to the print bed to hold up the strncture, remove heat, and minimize deformation due to solidification shrinkage. Because of these suppo1is, finished parts must be cut away from the build plate, and generally require additional machining to achieve the desired geometry. In this study, a carbon suspension was deposited in the 3 l 6L stainless steel powder bed at the interface between the support and the finished part. The added carbon reduces the co1Tosion resistance of the 3 l 6L. This allows full fusion of the support material to provide heat transfer and mechanical support during printing, while allowing the supports to etch preferentially by electrolytic etching. This causes the finished part to etch or break free from the supports without any need for machining, simplifying post-processing.

null

['Das, Anirban', 'Dasgupta, Niladri', 'Gurumoorthy, B.', 'Umarji, A. M.']

2019-06-13T14:05:35Z

2000

Mechanical Engineering

null

['https://hdl.handle.net/2152/74941', 'http://dx.doi.org/10.26153/tsw/2053']

eng

2000 International Solid Freeform Fabrication Symposium

Open

['LOM', 'polymer', 'Lamination']

Formulation of Lamination Conditions and Interface Studies using Acrylic Binder System for LOM 9

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0350f683-ba65-4471-b653-ecf8a3e0d936/download

null

A multicomponent binder-plasticiser system based on acrylates was formulated for making flexible tapes of Alumina (58 volume %), to be used for Laminated Object Manufacturing. Optimum lamination parameters were arrived at by viscosity measurement of the binder-plasticiser system and dilatometry of the compounded tapes . Lamination was done at five different temperatures (75, 85, 90, 95 and 110°C) with solvent (toluene-butanol) spray and under three different pressures ( below 50 psi). The interlaminar strength was measured and interface studies were made using SEM .The shrinkage along the Z direction during lamination was in the range of 1.7-3.5%. Highest interlaminar strength and defect free lamination could be achieved at the intermediate temperature of 90o C, due to sufficient reduction of polymer viscosity and presence of solvent.

null

['Zhou, Jack G.', 'He, Zongyan', 'Guo, Jian']

2019-03-12T16:49:03Z

1999

Mechanical Engineering

null

['https://hdl.handle.net/2152/73601', 'http://dx.doi.org/10.26153/tsw/743']

eng

1999 International Solid Freeform Fabrication Symposium

Open

['SALD', 'ECLD-SFF']

Fractal Growth Modeling of Electrochemical Deposition in Solid Freeform Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/be7947f7-b5a0-4494-aaae-8410e07441a8/download

null

A new rapid tooling technique ElectroChemical Liquid Deposition Based Solid Freeform Fabrication (ECLD-SFF) was introduced in this paper. In the ECLD-SFF a substrate made of or coated with conductive materials is connected to a DC power supply, and the substrate is put into a plating bath. A very thin metal pin is connected to the DC power as a positive electrode. Between the substrate and the tip of the pin there is a thin layer of metal powder. Under the effects of electric field, metal ions from electrode moving to chemical liquid will deposit onto the powder particle and growing so that the metal particles can be bound by the deposited materials to form freeform solid. By controlling the pin's movement and electrified time, a desired 3-D shape will be built through layer by layer scanning. ELCD-SFF distinguishes itself from other SFF techniques with advantages of products: high build rate, high accuracy, high density, low shrinkage and controllable microstructures. It has been found that the electrochemical deposition among metal particles during ECLD-SFF is a fractal growth process. The fractal dimension and the width of the deposited metal band are all related to electric field density, composition of electroplating liquid and processing time. Several models on the fractal growth between electrodes or metal particles were developed in order to explain these fractal growth phenomena and obtain desired process parameters and conditions for the ECLD-SFF process.

null

['Yang, Lei', 'Yan, Chunze', 'Shi, Yusheng']

2021-11-04T20:41:42Z

2017

Mechanical Engineering

null

['https://hdl.handle.net/2152/90023', 'http://dx.doi.org/10.26153/16944']

eng

2017 International Solid Freeform Fabrication Symposium

Open

['fracture mechanism', 'TPMS', 'Schoen Gyroid', 'cellular structures', 'selective laser melting']

Fracture Mechanism Analysis of Schoen Gyroid Cellular Structures Manufactured by Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d048d1d1-b78f-4aa4-baa5-61e35112188e/download

University of Texas at Austin

Ti-6Al-4V triply periodic minimal surface (TPMS) structures with biomorphics scaffold designs are expected to be the most promising candidates for many biological applications such as bone implants. Fracture is the main failure mode of Ti-6Al-4V cellular structures at room temperature. However, there is currently less investigation on general analysis about the fracture mechanism of Ti-6Al-4V TPMS cellular structures. In this work, a typical TPMS structure, Schoen Gyroid, was designed and porous Ti6Al4V Schoen Gyroid specimens were manufactured using Selective laser melting (SLM). Finite element analysis (FEA) method was employed to calculate the stress distribution under compression. The FEA results are used to predict the fracture positions, fracture zones as well as fracture mode. The uniaxial compression experiments were conducted and compared with the FEA results. The experimental and simulation results show high consistency.

null

['McNeil, J. Logan', 'Hamel, William R.', 'Penney, Joshua', 'Nycz, Andrzej', 'Noakes, Mark']

2021-11-18T16:54:47Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90426', 'http://dx.doi.org/10.26153/tsw/17347']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['large scale additive metals manufacturing', 'LSAMM', 'arbitrary directions', 'CAD']

Framework for CAD to Part of Large Scale Additive Manufacturing of Metal (LSAMM) in Arbitrary Directions

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9d7bd568-db7d-43ef-9be3-9a7cd2a96565/download

University of Texas at Austin

The purpose of this research is to provide a framework for Large Scale Additive Metals Manufacturing (LSAMM) in arbitrary directions. Traditionally, slicing and path planning is done along the gravity aligned direction of a part, causing more complex geometrical shapes to have unsupported overhangs. The overhangs can be managed using a part positioner or a powder bed process. A different framework for slicing and building parts out of gravity alignment could improve current capabilities of LSAMM processes. The presented research focuses on segmenting more complex geometrical parts into gravity aligned (GA), non-gravity aligned (NGA), and transition segments to help generate toolpaths. Initial research of segment planning for complex geometrical shapes will be presented, as well as current results from builds completed at the University of Tennessee-Knoxville. The completed builds show that more consistent thermal evolution of a part based on the path sequence and torch angle results in successful builds.

null

['Wang, Zhiyun', 'Liu, Renwei', 'Sparks, Todd', 'Liou, Frank']

2021-10-19T21:12:39Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89339

eng

2015 International Solid Freeform Fabrication Symposium

Open

['fused pellet modeling', 'void density', 'accuracy control', 'robot']

A Framework for Large Scale Fused Pellet Modeling (FPM) by An Industry Robot

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a4bfccfb-adaf-4e78-8718-f58f3553c416/download

University of Texas at Austin

Fused pellet modeling (FPM) is an important method in additive manufacturing technology, where granular material is used instead of filaments. In FPM, prototypes are constructed by the sequential deposition of material layers. As the size of the part increases, the problem of long build times and part deformation becomes critical. In this paper, methods for eliminating the void density during deposition and accuracy control principles for large scale FPM processes are studied. By analyzing the ab initio principles of this process, a mini extruder with variable pitch and progressive diameter screw for the large scale fused deposition is proposed. Based on polymer extrusion theory and non-Newtonian fluid properties, each of the design parameters are analyzed, such as the length of different function sections of screw, die shape of extruder nozzle, and the material properties. According to these analysis results, an extrusion process simulation for controlling the filament shape is carried out with multi-physics modeling software and proved the FPM could increase the building efficiency and deposition quality for large size parts.

null

['McNulty, T.', 'Bhate, D.', 'Zhang, A.', 'Kiser, M.A.', 'Ferry, L.', 'Suder, A.', 'Bhattacharya, S.', 'Boradkar, P.']

2021-11-04T19:41:26Z

2017

Mechanical Engineering

null

['https://hdl.handle.net/2152/90013', 'http://dx.doi.org/10.26153/16934']

eng

2017 International Solid Freeform Fabrication Symposium

Open

['biomimetic cellular materials', 'classification', 'design framework', 'additive manufacturing']

A Framework for the Design of Biomimetic Cellular Materials for Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6639ce49-e514-4465-b661-137d65b2699f/download

University of Texas at Austin

Cellular materials such as honeycombs and lattices are an important area of research in Additive Manufacturing due to their ability to improve functionality and performance. While there are several design choices when selecting a unit cell, it is not always apparent what the optimum cellular design for a particular application is. This becomes particularly challenging when seeking an optimal design for more than one function, or when the design needs to transition spatially between different functions. Nature abounds with examples of cellular materials that are able to achieve multifunctionality, but designers lack the ability to translate the underlying principles in these examples to their design tools. In this work, we propose a framework to bridge the gap between nature and designer. We present a classification of natural cellular materials based on their structure and function, and relate them in a manner amenable for use in guiding design for Additive Manufacturing.

null

['Weiss, Lee E.', 'Prinz, Fritz B.', 'Siewiork, Daniel P.']

2018-04-17T17:02:12Z

1991

Mechanical Engineering

doi:10.15781/T2J38M13F

http://hdl.handle.net/2152/64334

eng

1991 International Solid Freeform Fabrication Symposium

Open

['Thermal Spray', 'Net Shape Manufacture', 'Rapid Prototyping']

A Framework for Thermal Spray Shape Deposition: The MD* System

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8135518c-008f-444f-a18a-678fceaec339/download

null

This paper present.s t.he framework for a solid-freeform-fabrication syst.em based on thermal spray shape deposition t.o build mult.i-mat.erial st.ruct.ures by incremen tal build-up of t.hin cross-sect.ional layers. The basis of theMD* System (recursively, Mask and Deposit.) is to spray each layer using disposable masks to shape each layer. A thermal spray approach has the potential to build dense parts with desirable mechanical properties. Metal. ceramic, plastic, laminate, and composite structures can be deposited. Since l11asking enables selective deposition wit.hin a layer, complet.e assemblies composed of different mat.erials can be creat.ed in a single process. For example, int.egrated electronic/mechanical structures are feasible.

null

['Chatham, C.A.', 'Washington, A.L. II']

2023-03-29T14:47:18Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117674', 'http://dx.doi.org/10.26153/tsw/44553']

eng

2022 International Solid Freeform Fabrication Symposium

Open

Additive manufacturing

A Framework with Examples for Printing Thermosetting Polymers Using Laser Powder Bed Fusion Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c7f7c54a-d881-44e3-b919-1f45bbdabba1/download

null

Thermoset polymers possess traits arising from their covalently crosslinked network structure that are distinct from thermoplastic polymers. These traits can manifest as relative increases in the performance properties of chemical resistance, stiffness, and strength particularly at elevated temperature. Although these performance properties are desired from additively manufactured parts, there are few engineering grade thermosetting polymers commercially available for any additive manufacturing (AM) fabrication method. This work describes some of the challenges when processing and formulating thermosetting powder feedstocks for the laser powder bed fusion (L-PBF) mode of AM. The thermal curing properties of three different commercially available thermosetting polymers made via L-PBF are compared. Surface temperature profiles collected during printing are used to predict the extent of crosslinking through a rudimentary isoconversional model and are compared against post-print measurements of residual cure.

null

['Bampton, C.C', 'Burkett, R.']

2018-11-08T14:55:27Z

1995

Mechanical Engineering

doi:10.15781/T20V8B31P

http://hdl.handle.net/2152/69879

eng

1995 International Solid Freeform Fabrication Symposium

Open

['free form fabrication', 'SLS', 'alloy systems']

Free Form Fabrication of High Strength Metal Components and Dies

Conference paper

https://repositories.lib.utexas.edu//bitstreams/737b10dc-6599-4944-8309-89988dc5e3d4/download

null

A two-stage method has been devised for free form fabrication of nickel, iron and copper based alloy parts with shape and property control equal or superior to investment castings in the same base alloys. A major advantage of the approach is the ability to utilise commercially available selective laser sintering systems with virtually no modification from their standard configurations for plastic model generation. We have demonstrated the essential feasibility of shape, dimension and property control for complex, low production volume rocket engine components and for tools and dies in higher volume commercial production situations. This presentation is limited in scope to a brief overview of our recent progress.

null

['Griffith, M. L.', 'Keicher, D. M.', 'Atwood, C. L.', 'Romero, J. A.', 'Smugeresky, J. E.', 'Harwell, L. D.', 'Greene, D. L.']

2018-11-09T16:21:31Z

1996

Mechanical Engineering

doi:10.15781/T26689430

http://hdl.handle.net/2152/69929

eng

1996 International Solid Freeform Fabrication Symposium

Open

['CAD', 'LENS', 'stereolithography']

Free Form Fabrication of Metallic Components Using Laser Engineered Net Shaping (Lens)

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1975e01c-f42e-40b1-a26b-df29613a77d6/download

null

Solid free form fabrication is one ofthe fastest growing automated manufacturing technologies that has significantly impacted the length oftime between initial concept and actual part fabrication1 2. Starting with CAD renditions of new components, several techniques such as stereolithography3 and selective laser sintering4 are being used to fabricate highly accurate complex three-dimensional concept models using polymeric materials. Coupled with investment casting techniques, sacrificial polymeric objects are used to minimize costs and time to fabricate tooling used to make complex metal castings5 • This paper will describe recent developments in a new technology, known as LENSTM (Laser Engineered Net Shaping)6 7 8 9, to fabricate metal components directly from CAD solid models and thus further reduce the lead times for metal part fabrication. In a manner analogous to stereolithography or selective sintering, the LENSTM process builds metal parts line by line and layer by layer. Metal particles are injected into a laser beam, where they are melted and deposited onto a substrate as a miniature weld pool. The trace ofthe laser beam on the substrate is driven by the definition ofCAD models until the desired net-shaped densified metal component is produced.

null

['Chang, R.', 'Starly, B.', 'Sun, W.', 'Culbertson, C.', 'Holtorf, H.', 'Gonda, S.']

2020-02-27T20:43:56Z

2006

Mechanical Engineering

null

['https://hdl.handle.net/2152/80104', 'http://dx.doi.org/10.26153/tsw/7125']

eng

2006 International Solid Freeform Fabrication Symposium

Open

physiologically-based pharmokinetic

Freeform Bioprinting of Liver Encapsulated in Alginate Hydrogels Tissue Constructs for Pharmacokinetic Study

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c2f985cf-95e8-47de-9bb9-bf8682aaaebf/download

null

An in vitro model that can be realistically and inexpensively used to predict human response to various drug administration and toxic chemical exposure is needed. By fabricating a microscale 3D physiological tissue construct consisting of an array of channels and tissue-embedded chambers, one can selectively develop various biomimicking mammalian tissues for a number of pharmaceutical applications, for example, experimental pharmaceutical screening for drug efficacy and toxicity along with apprehending the disposition and metabolic profile of a candidate drug. This paper addresses issues relating to the development and implementation of a bioprinting process for freeform fabrication of a 3D cell-encapsulated hydrogel-based tissue construct, the direct integration onto a microfluidic device for pharmacokinetic study, and the underlying engineering science for the fabrication of a 3D microscale tissue chamber as well as its application in pharmacokinetic study. To this end, a prototype 3D microfluidic tissue chamber embedded with liver cells encapsulated within a hydrogel matrix construct is bioprinted as a physiological in vitro model for pharmacokinetic study. The developed fabrication processes are further validated and parameters optimized by assessing cell viability and liver cell phenotype, in which metabolic and synthetic liver functions are quantitated.

null

['Thomas, Albin', 'Kolan, Krishna C.R.', 'Leu, Ming C.', 'Hilmas, Gregory E.']

2021-10-21T21:04:19Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89448

eng

2015 International Solid Freeform Fabrication Symposium

Open

['freeform extrusion fabrication', 'bioactive glass scaffolds', 'titanium fibers', 'fiber reinforcement']

Freeform Extrusion Fabrication of Titanium Fiber Reinforced Bioactive Glass Scaffolds

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ea444e09-eb29-4399-b608-798da9287df8/download

University of Texas at Austin

Although implants made with bioactive glass have shown promising results for bone repair, their application in repairing load-bearing long bones is limited due to their low fracture toughness and fairly fast degradation response in vivo. In this paper, we describe our investigation of freeform extrusion fabrication of silicate based 13-93 bioactive glass scaffolds reinforced with titanium fibers. A composite paste was prepared with 13-93 bioactive glass filled with titanium fibers (~16 µm in diameter and aspect ratio of ~250) having a volume fraction of 0.4 vol. %. This paste was then extruded to fabricate scaffolds with an extrudate diameter of about ~0.8 mm. The sintered scaffolds, with and without titanium fibers, had measured pore sizes ranging from 400 to 800 µm and a porosity of ~50%. Scaffolds produced with 0.4 vol. % titanium fibers were measured to have a fracture toughness of ~0.8 MPa•m1/2 and a flexural strength of ~15 MPa. Bioactive glass scaffolds without titanium fibers had a toughness of ~ 0.5 MPa•m1/2 and strength of ~10 MPa. The addition of titanium fibers increased the fracture toughness of the scaffolds by ~70% and flexural strength by ~40%. The scaffolds’ biocompatibility and their degradation in mechanical properties, in vitro were assessed by immersing the scaffolds in a simulated body fluid over a period of one to four weeks.

null

['Mason, Michael S.', 'Huang, Tieshu', 'Landers, Robert G.', 'Leu, Ming C.', 'Hilmas, Gregory E.']

2020-02-28T20:43:36Z

9/14/06

Mechanical Engineering

null

['https://hdl.handle.net/2152/80120', 'http://dx.doi.org/10.26153/tsw/7141']

eng

2006 International Solid Freeform Fabrication Symposium

Open

solid freeform fabrication

Freeform Extrusion of High Solids Loading Ceramic Slurries, Part I: Extrusion Process Modeling

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f4ca0ddf-50b3-4e3f-90a5-c12e6b67fd54/download

null

A novel solid freeform fabrication method has been developed for the manufacture of ceramic-based components in an environmentally friendly fashion. The method is based on the extrusion of ceramic slurries using water as the binding media. Aluminum oxide (Al2O3) is currently being used as the part material and solids loading as high as 60 vol. % has been achieved. This paper describes a manufacturing machine that has been developed for the extrusion of high solids loading ceramic slurries. A critical component of the machine is the deposition system, which consists of a syringe, a plunger, a ram actuated by a motor that forces the plunger down to extrude material, and a load cell to measure the extrusion force. An empirical, dynamic model of the ceramic extrusion process, where the input is the commanded ram velocity and the output is the extrusion force, is developed. Several experiments are conducted and empirical modeling techniques are utilized to construct the dynamic model. The results demonstrate that the ceramic extrusion process has a very slow dynamic response, as compared to other non-compressible fluids such as water. A substantial amount of variation exists in the ceramic extrusion process, most notably in the transient dynamics, and a constant ram velocity may either produce a relatively constant steady-state extrusion force or it may cause the extrusion force to steadily increase until the ram motor skips. The ceramic extrusion process is also subjected to significant disturbances such as air bubble release, which causes a dramatic decrease in the extrusion force, and nozzle clogging, which causes the extrusion force to slowly increase until the clog is released or the ram motor skips.

null

['Mason, Michael S.', 'Huang, Tieshu', 'Landers, Robert G.', 'Leu, Ming C.', 'Hilmas, Gregory E.']

2020-02-28T20:47:32Z

9/14/06

Mechanical Engineering

null

['https://hdl.handle.net/2152/80121', 'http://dx.doi.org/10.26153/tsw/7142']

eng

2006 International Solid Freeform Fabrication Symposium

Open

solids loading ceramic slurry extrusion

Freeform Extrusion of High Solids Loading Ceramic Slurries, Part II: Extrusion Process Control

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d3102b2b-a7dd-412f-ba75-9e350117d86b/download

null

Part I of this paper provided a detailed description of a novel fabrication machine for high solids loading ceramic slurry extrusion and presented an empirical model of the ceramic extrusion process, with ram velocity as the input and extrusion force as the output. A constant force is desirable in freeform extrusion processes as it correlates with a constant material deposition rate and, thus, good part quality. The experimental results in Part I demonstrated that a constant ram velocity will produce a transient extrusion force. In some instances the extrusion force increased until ram motor skipping occurred. Further, process disturbances, such as air bubble release and nozzle clogging that cause sudden changes in extrusion force, were often present. In this paper a feedback controller for the ceramic extrusion process is designed and experimentally implemented. The controller intelligently adjusts the ram motor velocity to maintain a constant extrusion force. Since there is tremendous variability in the extrusion process characteristics, an on-off controller is utilized in this paper. Comparisons are made between parts fabricated with and without the feedback control. It is demonstrated that the use of the feedback control reduces the effect of process disturbances (i.e., air bubble release and nozzle clogging) and dramatically improves part quality.

null

['Asiabanpour, Bahram', 'Melbye, Jerry', 'Melbye, Vicky', 'Jensen, Evan', 'Shaw, Joshua']

2021-09-23T22:01:17Z

9/10/08

Mechanical Engineering

null

['https://hdl.handle.net/2152/88033', 'http://dx.doi.org/10.26153/tsw/14974']

eng

2008 International Solid Freeform Fabrication Symposium

Open

['facial reproduction', 'forensic anthropology', 'skull prototyping', 'Laser Scanning']

Freeform Fabrication Assists Forensic Scientists in the Identification of Unknown Victims

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7e5a526e-bdc1-4935-9580-f07cd20b0c95/download

null

According to the International Homicide Investigators Association, there are currently over 40,000 unidentified bodies being held in coroner‟s and medical examiner‟s offices across the United States. Over half are estimated to be victims of homicide, and all are awaiting positive identification. One technique utilized by forensic anthropologists to establish the identity of unknown skeletal or decomposed individuals is the use of facial reproduction. In facial reproduction, soft tissue approximating muscle and skin is added to the skull in an attempt to reflect how the individual looked during life. Soft tissue depths at specific locations (i.e., certain craniofacial landmarks) are known and have been standardized according to an individual‟s sex, age, ancestry, and body type. For the most part, facial reproduction is still accomplished manually by adding layers of soft clay to represent tissue on the actual skull of the deceased individual. This method is quite time-consuming (often taking two or more weeks) and often not feasible because the skull may be damaged, or the use of clay overlying the actual skull may destroy evidence. To overcome these limitations, researchers have recently turned to Computed Tomography (CT scan) technology to generate CAD files of unidentified skulls, which are then modeled and recreated with rapid prototyping machines. One limitation of this method is that it is dependent on the initial CT scanning instrument, which is not portable and requires that the unidentified remains be removed from their original storage sites (typically morgue coolers or crime scenes) to the location where CT scanning instruments are available (often hospital or clinical settings). Because many of these unidentified remains are either skeletonized or are in various stages of decomposition, the transport of these bodies to locations with CT scanning machines is often not possible or permissible. In this paper, we first propose a new method to rapid prototype skulls via stereolithography (STL) files generated by hand-held portable laser scanners, as opposed to using CT scanning machines. These rapid prototypes can then be fabricated for facial reproduction, negating the use of the actual skull, and not requiring the body be removed from its original location. Also, results of the facial reproduction for an active case are presented. Secondly, we outline preliminary results of a new computerized facial reproduction and superimposition method, which accurately models tissue depth and is not dependent on the manual application of clay.

null

['Malone, Evan', 'Rasa, Kian', 'Cohen, Daniel', 'Isaacson, Todd', 'Lashley, Hilary', 'Lipson, Hod']

2019-11-20T17:16:48Z

2003

Mechanical Engineering

null

['https://hdl.handle.net/2152/78487', 'http://dx.doi.org/10.26153/tsw/5572']

eng

2003 International Solid Freeform Fabrication Symposium

Open

Structural-Electric

Freeform Fabrication of 3D Zinc-Air Batteries and Functional Structural-Electric Assemblies

Conference paper

https://repositories.lib.utexas.edu//bitstreams/646535f1-76cd-4d03-af94-77749d2ec7a3/download

null

This paper reports on a fabrication platform and extensions to deposition-based processes that permit freeform fabrication of three-dimensional functional assemblies with embedded conductive wiring and power sources. Structure and joints are produced by fused deposition of thermoplastics and deposition of elastomers. Conductive wiring is achieved by deposition of various low-melting-point alloys and conductive pastes. Batteries based on zinc-air chemistry are produced by deposition of zinc, electrolyte, and catalysts, with separator media and electrodes. Details of the deposition processes are provided and several printed assemblies are demonstrated.

This work was supported in parts by the U.S. Department of Energy, grant DE-FG02- 01ER45902.

null

['Malone, Evan', 'Lipson, Hod']

2020-03-10T16:04:27Z

9/5/07

Mechanical Engineering

null

['https://hdl.handle.net/2152/80219', 'http://dx.doi.org/10.26153/tsw/7238']

eng

2007 International Solid Freeform Fabrication Symposium

Open

electromechanical

Freeform Fabrication of a Complete Electrochemical Relay

Conference paper

https://repositories.lib.utexas.edu//bitstreams/13fbb70e-d88a-4034-b228-7fbb3ede1495/download

null

['Kyogoku, Hideki', 'Hagiwara, Masashi', 'Shinno, Toshifumi']

2021-09-30T13:22:46Z

9/23/10

Mechanical Engineering

null

['https://hdl.handle.net/2152/88231', 'http://dx.doi.org/10.26153/tsw/15172']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['selective laser sintering', 'selective laser melting', 'aluminum alloy', 'freeform fabrication', 'Al-12Si alloy']

Freeform Fabrication of Aluminum Alloy Prototypes Using Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/07303ac8-a191-4ea0-8813-6821adeaf6d1/download

University of Texas at Austin

In this study, a direct selective laser sintering/melting machine was designed and constructed. The machine has a 50 W Yb-fiber laser, a galvanometer scanner and a powder delivery and build system. It was confirmed that the machine works well. The fabrication conditions of aluminum alloys were investigated using the machine. The optimum laser power, scan speed and scan pitch were investigated by experiments. The effect of addition of metal powder as additives on laser scanning process was investigated to fabricate the sound laser-scanned body of aluminum alloys based on Al-12Si alloy. It was found that the smooth single-scan track can be fabricated at lower laser power and higher scan speed by the addition of a laser absorption material. An aluminum alloy prototype was successfully produced using optimum laser scanning conditions.

null

['Han, Li-Hsin', 'Mapili, Gazill', 'Chen, Shaochen', 'Roy, Krishnendu']

2020-03-10T15:05:28Z

9/4/07

Mechanical Engineering

null

['https://hdl.handle.net/2152/80213', 'http://dx.doi.org/10.26153/tsw/7232']

eng

2007 International Solid Freeform Fabrication Symposium

Open

scaffolds

Freeform Fabrication of Biological Scaffolds by Projection Photopolymerization

Conference paper

https://repositories.lib.utexas.edu//bitstreams/899be073-b465-41af-ae54-d1f011840323/download

null

This article presents a micro-manufacturing method for direct, projection printing of 3- dimensional (3D) scaffolds for applications in the field of tissue engineering by using a digital micro-mirror-array device (DMD) in a layer-by-layer process. Multi-layered scaffolds are microfabricated using curable materials through an ultraviolet (UV) photopolymerization process. The pre-patterned UV light is projected onto the photocurable polymer solution by creating the “photomask” design with graphic software. Poly (ethylene glycol) diacrylate (PEGDA), is mixed with a small amount of dye (0.3 wt %) to enhance the fabrication resolution of the scaffold. The DMD fabrication system is equipped with a purging mechanism to prevent the accumulation of oligomer, which could interfere with the feature resolution of previously polymerized layers. The surfaces of the pre-designed, multi-layered scaffold are covalently conjugated with fibronectin for efficient cellular attachment. Our results show that murine marrow-derived progenitor cells successfully attached to fibronectin-modified scaffolds.

null

['Malone, Evan', 'Lipson, Hod']

2020-02-17T15:16:42Z

9/1/04

Mechanical Engineering

null

['https://hdl.handle.net/2152/80008', 'http://dx.doi.org/10.26153/tsw/7033']

eng

2004 International Solid Freeform Fabrication Symposium

Open

compact fabrication system

Freeform Fabrication of Electroactive Polymer Actuators and Electromechanical Devices

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0dfae166-ef2f-4e27-a047-faead286e5d0/download

null

In pursuit of the goal of producing complete electromechanical systems entirely via solid freeform fabrication, we are developing a library of mutually compatible, functional, freeform elements. Several essential elements – actuation, sensing, and control electronics - still remain to be incorporated into this library. Conducting polymers (CP) are a class of materials which can be used to produce all of these functionalities. Meanwhile, research into actuatable “smart” materials has produced other candidate materials for freeform fabricated actuators that are compatible with our library. We have succeeded in manually producing air-operable actuators that have processing and operating requirements that are compatible with our power source and mechanical component library elements. A survey of candidate actuator materials is presented, experiments performed with two types of actuator materials are described, and complete SFF-producible actuator devices are demonstrated.

null

['Malone, Evan', 'Lipson, Hod']

2020-02-24T15:39:32Z

8/3/05

Mechanical Engineering

null

['https://hdl.handle.net/2152/80085', 'http://dx.doi.org/10.26153/tsw/7106']

eng

2005 International Solid Freeform Fabrication Symposium

Open

Solid Freeform Fabrication

Freeform Fabrication of Ionomeric Polymer-Metal Composite Actuators

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8e5c111e-d65f-4b55-a069-e5e76126c7c5/download

null

Ionomeric polymer-metal composite (IPMC) actuators are a type of soft electromechanically active material which offers large displacement, rapid motion with only ~1V stimulus. IPMC’s are entering commercial applications in toys (Ashley 2003) and biomedical devices (Soltanpour 2001; Shahinpoor 2002; Shahinpoor, Shahinpoor et al. 2003; Soltanpour and Shahinpoor 2003; Soltanpour and Shahinpoor 2004), but unfortunately they can only actuate by bending, limiting their utility. Freeform fabrication offers a possible means of producing IPMC with novel geometry and/or tightly integrated with mechanisms which can yield linear or more complex motion. We have developed materials and processes which allow us to freeform fabricate complete IPMC actuators and their fabrication substrate which will allow integration within other freeform fabricated devices. We have produced simple IPMC’s using our multiple material freeform fabrication system, and have demonstrated operation in air for more than 40 minutes and 256 bidirectional actuation cycles. The output stress scaled to input power is two orders of magnitude inferior to that of the best reported performance for devices produced in the traditional manner, but only slightly inferior to devices produced in a more similar manner. Possible explanations and paths to improvement are presented. Freeform fabrication of complete electroactive polymer actuators in unusual geometries, with tailored actuation behavior, and integrated with other freeform fabricated active components, will enable advances in biomedical device engineering, biologically inspired robotics, and other fields. This work constitutes the first demonstration of complete, functional, IPMC actuators produced entirely by freeform fabrication.

null

['Havener, Robin', 'Boyea, John', 'Malone, Evan', 'Bernards, Daniel', 'DeFranco, John', 'Malliaras, George', 'Lipson, Hod']

2020-03-09T13:36:50Z

8/21/07

Mechanical Engineering

null

['https://hdl.handle.net/2152/80175', 'http://dx.doi.org/10.26153/tsw/7194']

eng

2007 International Solid Freeform Fabrication Symposium

Open

electrochemical transistors

Freeform Fabrication of Organic Electrochemical Transistors

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6c442b72-8949-4809-9da3-8b669cd362ef/download

null

['Lipton, Jeffrey', 'Boban, Mathew', 'Hiller, Jonathan', 'Lipson, Hod']

2021-09-30T23:54:23Z

2010

Mechanical Engineering

null

['https://hdl.handle.net/2152/88299', 'http://dx.doi.org/10.26153/tsw/15240']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['cellular materials', 'stochastic foam', 'closed celled foams', 'viscous thread']

Freeform Fabrication of Stochastic and Ordered Cellular Structures

Conference paper

https://repositories.lib.utexas.edu//bitstreams/16cef7be-06a8-4769-aa06-8d451023e6a8/download

University of Texas at Austin

Cellular materials provide a unique challenge to SFF technology. Such materials have unique properties of low mass, high strength, and good insulation properties. To produce such cellular structures, SFF systems require a designed microstructure with a feature size significantly lower than the resolution of the process. In this paper, we examine means of producing stochastic foams using the instability of a viscous thread and various methods for production of closed celled foams. These techniques allow for the production of foams without the need for pre-described cell structures. Such foams, when made from elastic materials can act as novel actuating materials.

null

Rotheroe, Kevin Chaite

2019-10-22T17:54:15Z

2002

Mechanical Engineering

null

['https://hdl.handle.net/2152/76325', 'http://dx.doi.org/10.26153/tsw/3414']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Optimized

The Freeform Fabrication of Structurally Optimized and Complexly Shaped Metal Tubular Components

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b21b6437-4fad-4a05-af0d-cdb96be5d51d/download

null

The service conditions of many structural frames composed of tubular metal components would ideally warrant the use of high strength-to-weight ratio components with shapes and internal geometries that respond to context-specific structural requirements. Commercially available and emerging solid freeform fabrication technologies can be utilized to indirectly or directly manufacture metal tubular structural components with optimizing features that cannot otherwise be manufactured. The results of prototyping experiments demonstrating the viability and potential of this application of additive manufacturing will be presented. This presentation will discuss successful prototype 356 aluminum and 316 stainless steel internally reinforced freeform tubular components manufactured indirectly using expendable patterns made by selective laser sintering and 3D printing. The application of laser and metal powder based freeform fabrication technologies that provide superior material properties will also be discussed, especially in terms of requirements for multi-axis deposition and sophisticated path planning software, and the implications of voxel- or layer-based functionally gradient materials.

null

['Dcosta, D.J.', 'Sun, W.', 'Raghy-El, T.']

2019-10-10T17:20:51Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76175', 'http://dx.doi.org/10.26153/tsw/3264']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Fabrication

Freeform Fabrication of Ti3SiC2 Structures

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7882d446-272c-4065-ae71-8c037b730722/download

null

This paper introduces a three-stage process to fabricate highly dense Ti3SiC2 structures. The properties of Ti3SiC2 material, the synthesis of the ceramic powder, the procedure involved in the 3-stage fabrication process and the preliminary results on fabricating fully dense Ti3SiC2 structures are presented. The characterization and microstructure evaluation of the mechanical, morphological and structural properties covering the compressive strength, Vickers micro hardness, damage tolerance, thermal shock, shrinkage and porosity of Ti3SiC2 structures printed using the 3-stage process are presented.

null

['Berry, Megan E.', 'Malone, Evan', 'Lipson, Hod']

2020-02-21T16:07:27Z

8/26/05

Mechanical Engineering

null

['https://hdl.handle.net/2152/80066', 'http://dx.doi.org/10.26153/tsw/7088']

eng

2005 International Solid Freeform Fabrication Symposium

Open

freeform fabricated circuits

Freeform Fabrication of Zinc Air Batteries with Tailored Geometry and Performance

Conference paper

https://repositories.lib.utexas.edu//bitstreams/278cfb21-e669-437f-923f-3e495238c342/download

null

This work is focused on the freeform fabrication of complete zinc-air batteries. This method of production gives great freedom in the geometry and construction of the battery, allowing tailoring of the output characteristics, and the possibility of embedding a customized battery within a larger integrated freeform fabricated device. Our batteries utilize a gelling agent to prevent phase separation in the zinc anode and catalyst layers, permitting the use of nozzles down to 1.3mm in diameter. Polyvinyl alcohol is utilized for the separator layer, which replaces the unprintable paper separator used in commercial batteries. With various freeform batteries we have achieved a specific capacity of 60mAh/g of zinc, an average power 7.25mW, and continuous service life of 63h, all with a load of 100 ohms. The specific capacity of our freeform batteries is about 1 order of magnitude lower than that of commercial zinc-air batteries, although under different test conditions. We have investigated the effect of cell active surface area on performance for a cylindrical cell-geometry, and have produced a flexible, two-cell battery with unusual geometry. The tailoring of performance and geometry possible with freeform fabrication will be of great value in the design of optimized smart devices with unusual geometry, portable electronics, and prototypes.

null

['Leu, Ming C.', 'Adamek, Erik B.', 'Huang, Tieshu', 'Hilmas, Greg E.', 'Dogan, Faith']

2021-09-23T20:26:42Z

9/10/08

Mechanical Engineering

null

['https://hdl.handle.net/2152/88022', 'http://dx.doi.org/10.26153/tsw/14963']

eng

2008 International Solid Freeform Fabrication Symposium

Open

['Selective Laser Sintering', 'SLS', 'zirconium diboride', 'freeform fabrication', 'mechanical engineering']

Freeform Fabrication of Zirconium Diboride Parts Using Selective Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1b80fd9f-f748-48da-ac1a-217cceb9f0fb/download

null

Using the Selective Laser Sintering (SLS) process, both flexural test bars and 3D fuel injector components have been fabricated with zirconium diboride (ZrB2) powder. Stearic acid was selected as the binder. Values of SLS process parameters were chosen such that the green parts could be built with sharp geometrical features and that the sintered parts could have good mechanical properties. After binder burnout and sintering, the SLS fabricated ZrB2 test bars achieved 80% theoretical density, and the average flexural strength of the sintered samples was 195 MPa. These values demonstrate the feasibility of the SLS process for freeform fabrication of 3D parts with the ultra high temperature ceramic.

null

['Rock, Stephen J.', 'Gilman, Charles R.', 'Misiolek, Wojciech Z.', 'Walczyk, Daniel F.']

2018-11-09T16:32:09Z

1996

Mechanical Engineering

doi:10.15781/T2T14V847

http://hdl.handle.net/2152/69932

eng

1996 International Solid Freeform Fabrication Symposium

Open

['SFF', 'Rapid Tooling', 'freeze molding']

Freeform Powder Molding for Rapid Tooling

Conference paper

https://repositories.lib.utexas.edu//bitstreams/dab977f4-9c13-414b-bbe4-935a6e3a04ba/download

null

Tooling development can be quite time consuming and costly. Several iterations may be required, and later product or process modifications may necessitate tooling redesign. Rapid prototyping techniques capable of meeting the structural requirements of short-run and end-use tooling will have a significant impact on the product development cycle. This paper presents a technique for producing tooling using the Freeform Powder Molding process. Resulting tooling can be made from a wide variety of readily available metal powders, and mechanical properties can be tailored for customized tool design and fabrication. The example presented in this paper focuses on the rapid production of tooling for sheet metal forming

null

['Huang, T.S.', 'Doiphode, N.D.', 'Rahaman, M.N.', 'Leu, M.C.', 'Bal, B.S.', 'Day, D.E.']

2021-10-04T20:05:59Z

9/23/10

Mechanical Engineering

null

['https://hdl.handle.net/2152/88332', 'http://dx.doi.org/10.26153/tsw/15271']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['freeze extrusion fabrication', 'bioactive glass', 'solid freeform fabrication', 'bone repair']

Freeze Extrusion Fabrication of 13-93 Bioactive Glass Scaffolds for Bone Repair

Conference paper

https://repositories.lib.utexas.edu//bitstreams/bac9a092-59b5-4624-946b-d36df0aa4d27/download

University of Texas at Austin

There is an increasing demand for synthetic scaffolds with the requisite biocompatibility, internal architecture, and mechanical properties for the bone repair and regeneration. In this work, scaffolds of a silicate bioactive glass (13-93) were prepared by a freeze extrusion fabrication (FEF) method and evaluated in vitro for potential applications in bone repair and regeneration. The process parameters for FEF production of scaffolds with the requisite microstructural characteristics, as well as the mechanical and cell culture response of the scaffolds were evaluated. After binder burnout and sintering (60 min at 700°C), the scaffolds consisted of a dense glass network with interpenetrating pores (porosity ≈ 50%; pore width = 100−500 µm). These scaffolds had a compressive strength of 140 ± 70 MPa, which is comparable to the strength of human cortical bone and far higher than the strengths of bioactive glass and ceramic scaffolds prepared by more conventional methods. The scaffolds also supported the proliferation of osteogenic MLO-A5 cells, indicating their biocompatibility. Potential application of these scaffolds in the repair and regeneration of load-bearing bones, such as segmental defects in long bones, is discussed.

null

['Huang, Tieshu', 'Mason, Michael S.', 'Hilmas, Gregory E.', 'Leu, Ming C.']

2020-02-20T20:00:26Z

2005

Mechanical Engineering

null

https://hdl.handle.net/2152/80046

eng

2005 International Solid Freeform Fabrication Symposium

Open

['Fused Deposition Modeling', 'Fused Deposition of Ceramic']

Freeze-form Extrusion Fabrication of Ceramics

Conference paper

https://repositories.lib.utexas.edu//bitstreams/03f6e416-3880-422f-9987-e54a84a76190/download

null

A novel, environmentally friendly solid freeform fabrication method called Freeze-form Extrusion Fabrication (FEF) has been developed for the fabrication of ceramic-based components. The method is based on deposition of ceramic pastes using water as the media. The ceramic solids loading can be 50 vol. % or higher and initial studies have focused on the use of aluminum oxide (Al2O3). The FEF system components and their interaction are examined, and the main process parameters affecting part geometry defined. 3-D shaped components have been fabricated by extrusion deposition of the ceramic paste in a layer-by-layer fashion. The feasibility of this process has been demonstrated by building components having a simple geometry, such as cylinders and solid or hollow cones. Hollow cones have also been fabricated to demonstrate the ability to build structures with sloped walls.

null

['Leu, Ming C.', 'Tang, Lie', 'Deuser, Brad', 'Landers, Robert G.', 'Hilmas, Gregory E.', 'Zhang, Shi', 'Watts, Jeremy']

2021-10-04T20:38:10Z

8/17/11

Mechanical Engineering

null

['https://hdl.handle.net/2152/88342', 'http://dx.doi.org/10.26153/tsw/15281']

eng

2011 International Solid Freeform Fabrication Symposium

Open

['Freeze-form Fabrication', 'three-dimensional structures', 'graded composite materials', 'material composition']

Freeze-Form Extrusion Fabrication of Composite Structures

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ac0a470d-efc5-4ff5-adb5-cbce18006d4d/download

University of Texas at Austin

A Freeze-form Extrusion Fabrication (FEF) process capable of making three-dimensional (3D) parts and structures with graded composite materials is presented in this paper. The process development includes the design and manufacture of a gantry machine with a triple-extruder mechanism and the associated electronics hardware and computer software for fabricating functionally graded parts from multiple aqueous pastes. A rheological behavior study with Al2O3 paste is performed to identify an efficient binder for transforming the paste into a pseudoplastic with a high yield stress. A green part is first fabricated using the triple-extruder FEF machine in a layer-by-layer manner with the desired material gradients. The green part is then freeze-dried, its binder removed through a burnout process to obtain a brown part, and the final part obtained by sintering. The final part is analyzed using energy dispersive X-ray spectroscopy (EDS) to determine its material composition. The results demonstrate that the FEF process can be used to fabricate functionally graded composite parts with pre-specified gradients.

null