ccm/sff-papers · Datasets at Hugging Face

['Bernardo, Jesse', 'Samavedi, Satyavrata', 'Williams, Christopher B.', 'Whittington, Abby R.']

2021-10-05T14:30:06Z

8/17/11

Mechanical Engineering

null

['https://hdl.handle.net/2152/88379', 'http://dx.doi.org/10.26153/tsw/15318']

eng

2011 International Solid Freeform Fabrication Symposium

Open

['Fused Deposition Modeling', 'biomimetic mineralization', 'tissue scaffold', 'additive manufacturing']

Indirect Tissue Scaffold Fabrication via Fused Deposition Modeling and Biomimetic Mineralization

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8e13538a-e2df-4d79-ac97-00459e8bc73c/download

University of Texas at Austin

To alleviate material limitations of the additive manufacture of tissue scaffolds, researchers have looked to indirect fabrication approaches. The feature resolution of these processes is limited however, due to the viscous ceramic slurries that are typically employed. To alleviate these limitations, the authors look to an indirect fabrication process wherein a pattern, created using Fused Deposition Modeling, is biomimetically mineralized with an aqueous simulated body fluid, which forms a bonelike hydroxyapatite throughout the scaffold pattern. Mineralized patters are then heat treated to pyrolyze the pattern and sinter the minerals. With this process, scaffolds were created with wall thicknesses as small as 150 m and internal channel diameters of 280-340 m, an appropriate range for bone tissue engineering.

null

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

2021-11-11T15:16:10Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90216', 'http://dx.doi.org/10.26153/tsw/17137']

eng

2018 International Solid Freeform Fabrication Symposium

Open

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

Individual and Coupled Contributions of Laser Power and Scanning Speed Towards Process-Induced Porosity in Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2945cae3-af56-4ce6-88f5-60ff222fcfcb/download

University of Texas at Austin

Porosity is an undesirable characteristic of selective laser melting (SLM) process and keyhole pores are formed when the energy density is very high which leads to deep penetration melting. In this study, single-track SLM experiments using Ti-6Al-4V powder were designed and conducted with combination of varied levels of the laser power and the scanning speed, intended to obtain the same energy density. Three energy densities: 0.32 J/mm, 0.4 J/mm and 0.48 J/mm were selected to investigate the influence of laser power versus scanning speed on porosity. Pore numbers and volumes was analyzed using micro-scale computed tomography. The results indicated that the pore formation is affected more by the change in the power than the scanning speed while keeping the energy density constant. As the power increased from around 20 W to 140 W, total pore volume increased, whereas pore volume decreased when power increased from 140 W to 195W.

null

['Omer, L.', 'Uddin, M.J.', 'Chowdhury, H.', 'Martinez, J.', 'Sporn, I.', 'Dudek, B.', 'Tate, J.']

2023-03-29T14:45:38Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117673', 'http://dx.doi.org/10.26153/tsw/44552']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Fused Filament Fabrication', 'Thermoset Curing', 'Advanced Composites', 'Additive Manufacturing', 'Polymer Matrix Composites', 'Induction Heating']

Induction Initiated Curing of Additively Manufactured Thermoset Composites

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8dfeebdd-7c0f-4b7b-a33d-d5c8bc76131b/download

null

Additive Manufacturing (AM) has provided a new potential for material customization through the reduction in geometric constraints of products. The freeform geometry produced using AM allows for the creation of optimized structural parts that reduce weight and material waste. In addition, AM reduces production time by providing a model to product workflow with limited requirements for tooling and machine setup in advance. However, current work in printing thermoset composite parts is limited. One of the confounding factors in the AM of thermoset composites involves in situ curing of the composite resin system. This research proposes the creation of an additive manufacturing process for thermoset composites based upon induction initiated thermoset curing. The use of induction-based curing will allow the production of parts without the normal constraint of either oven or autoclave curing. A rapid curing resin system will be reinforced using milled fiber reinforcement and doped with a ferromagnetic susceptor to induce homogenous heating and curing of the resin in situ. The resulting composite will be evaluated for mechanical performance versus oven cure samples. Scanning electron microscopy in tandem with energy dispersive x-ray spectroscopy will be used to validate homogenous particle dispersion. Lastly, differential scanning calorimetry will be used to compare the degree of polymer conversion between induction and conventional curing.

null

['Regenfuβ, P.', 'Hartwig, L.', 'Klötzer, S.', 'Ebert, R.', 'Brabant, Th.', 'Petsch, T.', 'Exner, H.']

2020-02-17T15:23:52Z

2004

Mechanical Engineering

null

['https://hdl.handle.net/2152/80009', 'http://dx.doi.org/10.26153/tsw/7034']

eng

2004 International Solid Freeform Fabrication Symposium

Open

selective laser sintering

Industrial Freeform Generation of Microtools by Laser Micro Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/640141e0-9cf2-48d1-8894-b5349e5a476d/download

null

Precision tools with structural resolution reaching the 20 micrometer range can be generated on an industrial scale by “laser micro sintering”. Components featuring aspect ratios above 12 and a roughness Ra down to 1.5 micrometers have already been produced from sub micrometer grained metal powders. The components can be generated either firmly attached to a substrate or fixed in an easily separable mode. If supporting structures are employed, undercuts up to 90° are feasible, without, a process parameter dependent maximum angles of undercut below 90° are obtained. The process has been introduced into the market, labeled microSINTERING by 3D-Micromac AG.

null

['Nyrhila, Olli', 'Kotila, Juha', 'Lind, Jan-Erik', 'Syvanen, Tatu']

2019-02-26T17:02:42Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73487', 'http://dx.doi.org/10.26153/tsw/637']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['Direct Metal Laser Sintering', 'Electrolux Rapid Development']

Industrial Use of Direct Metal Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6cf51b16-edc9-4229-9d70-5202663e15a8/download

null

The Direct Metal Laser Sintering (DMLS) process was developed a few years ago by Electrolux Rapid Development (ERD) and EOS. DMLS has now been in commercial use for more than two years at Electrolux and also at other European prototype manufacturers, and the machine itself is also available for purchase. This paper describes the development ofthe process in particular the industrialization of DMLS and how it has changed the prototype mould manufacturing process at Electrolux. Issues concerning the materials used are also described, as well as the necessary posttreatment methods in prototype mould manufacturing. Several case studies, from various injection mouldings to pressure die-casting, are presented.

null

['Anarfi, Richard', 'Kwapong, Benjamin', 'Fletcher, Kenneth', 'Sparks, Todd', 'Flood, Aaron', 'Joshi, Mugdha']

2021-12-07T17:18:26Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90726', 'http://dx.doi.org/10.26153/tsw/17645']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'autoencoder', 'deep learning']

Inference of Metal Additive Manufacturing Process States via Deep Learning Techniques

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2adee999-13b3-4d7f-8d2d-6fd5cc74db0e/download

University of Texas at Austin

Numerical simulation of metal additive processes are computationally intensive tasks. Iterative solution techniques for physics-based methods can lead to lengthy solution times and convergence problems, particularly if fluid dynamics of the melt pool are considered. Deep learning (DL) techniques offer an opportunity to infer solution results quickly. In this paper we propose a DL method based on long short term memory (LSTM), network trained on rendered images from a metal AM process simulation and CAM data. We obtained vector representations of the images by training on an autoencoder. LSTM is a memory based recurrent neural networks (RNN) that is capable of processing long sequences of data while combating temporal stability problems encountered with conventional recurrent neural networks (RNN)s. This LSTM network is used to predict images of the process given scan path and process information. This could later be used to compare with process monitoring systems as part of a quality assurance or process control schema.

null

['Buls, S.', 'Craeghs, T.', 'Clijsters, S.', 'Kempen, K.']

2021-10-07T17:58:33Z

8/16/13

Mechanical Engineering

null

['https://hdl.handle.net/2152/88496', 'http://dx.doi.org/10.26153/tsw/15430']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['Selective Laser Melting', 'galvano based laser scanner', 'total scan time', 'optimization']

The Influence of a Dynamically Optimized Galvano Based Laser Scanner on the Total Scan Time of SLM Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/fd1d9c52-3ab6-4dcd-8507-963dca43a45e/download

University of Texas at Austin

Most commercially available Selective Laser Melting (SLM) machines use galvano based laser scanner deflection systems. This paper describes the influence of the dynamical optimization of such galvano based laser scanner on the total scan time. The system identification of a galvano laser scanner was performed in combination with the development and implementation of an optimal ‘Input Shaper’. Tests were performed on lattice structured SLM parts. The process time was hereby compared, with and without the use of the optimal ‘Input Shaper’. Significant scan time reduction was observed when using the optimal ‘Input Shaper’.

null

['Fashanu, O.', 'Buchely, M.F.', 'Hussein, R.', 'Anandan, S.', 'Spratt, M.', 'Newkirk, J.', 'Chandrashekhara, K.', 'Misak, H.', 'Walker, M.A.']

2021-11-11T14:56:02Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90209', 'http://dx.doi.org/10.26153/tsw/17130']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'SLM', 'stainless steel', 'hatch angle', 'build orientation']

The Influence of Build Parameters on the Compressive Properties of Selective Laser Melted 304L Stainless Steel

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c9200f50-2342-4713-9fef-b5af9024e042/download

University of Texas at Austin

Process parameters used during Selective Laser Melting (SLM) process have significant effects on the mechanical properties of the manufactured parts. In this study, the influence of two build parameters (build orientation and hatch angle) on the compressive properties of 304L stainless steel was evaluated. SLM 304L samples were manufactured using three hatch angles, 0°, 67°,105° and two orientations, z-direction and x-direction, and tested using a compression frame according to ASTM E9-09. Bulk density was measured according to ASTM C373-17 before compression. Properties evaluated were the bulk density, yield strength, strength at 15% plastic-strain and strength at 30% plastic-strain. Results showed that bulk density varied minutely with respect to variation in hatch angle and build orientation, but compressive yield strength and plastic flow stress were strongly influenced by these two process parameters. Highest compressive yield strength was measured when samples were built in the x-direction using hatch angle 67°.

null

['Kummert, C.', 'Schmid, H.-J.']

2021-11-11T16:11:00Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90231', 'http://dx.doi.org/10.26153/tsw/17152']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['PA613', 'scanning parameters', 'scanning strategy', 'build part properties', 'contour', 'selective laser sintering']

The Influence of Contour Scanning Parameters and Strategy on Selective Laser Sintering PA613 Build Part Properties

Conference paper

https://repositories.lib.utexas.edu//bitstreams/46a9974c-34db-4817-906b-beda64ecf569/download

University of Texas at Austin

Qualification of new materials for the laser sintering (SLS) process includes development of suitable parameters in terms of optimal part properties. Especially laser scanning parameters influence part porosity and therewith mechanical performance. In the present work tensile specimens were built of PA613 a new LS polyamide delivered by Evonik and was processed on an EOSINT P396. As build parameters have to be developed for the new material, scanning parameters and strategy of the PA613 specimen contour were varied in different ways. Resulting part properties were investigated by XCT-analysis as well as by tensile tests. The three-dimensional part porosity, pore density and arrangement were analyzed in relation to used laser scanning parameters and resulting mechanical properties. The investigations help to understand the existing correlations between laser energy input, part porosity and mechanical performance and therewith to find optimized build parameters for the new material.

null

['Colton, Trenton', 'Liechty, Joseph', 'McLean, Alden', 'Crane, Nathan']

2021-11-16T15:54:42Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90322', 'http://dx.doi.org/10.26153/tsw/17243']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['drop velocity', 'droplet spacing', 'equilibrium saturation', 'binder jetting']

Influence of Drop Velocity and Droplet Spacing on the Equilibrium Saturation Level in Binder Jetting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5e771f55-3222-47a3-8181-5738da4caca4/download

University of Texas at Austin

Understanding the equilibrium saturation level is crucial to Binder Jetting (BJ). Saturation level influences dimensional accuracy, print time, green strength, and final material properties. Improved understanding of the saturation level can reduce development time for new materials and improve existing processes in BJ. Attempts have been made to predict saturation levels of parts with simple calculations from droplet primitives and capillary pressure. There is, however, limited experimental validation for these methods and they do not include the impact of drop velocity and droplet spacing. This study incorporates the influences of drop velocity and droplet spacing on the saturation level of the part. Drop primitives of varying droplet velocity and droplet spacing were compared. Results show that velocity impacts the feasible parameter space.

null

['Sinha, Swapnil', 'Meisel, Nicholas A.']

2021-10-27T22:43:26Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89637

eng

2016 International Solid Freeform Fabrication Symposium

Open

['embedding', 'tensile strength', 'material extrusion', '3D printing']

Influence of Embedding Process on Mechanical Properties of Material Extrusion Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2414abcc-f540-4531-9759-2429a1d05771/download

University of Texas at Austin

The layer-by- layer deposition of material in Additive Manufacturing (AM) introduces the capability for in-situ embedding of functional components into printed parts. The typical embedding process involves, i) designing the cavity for the embedded component, ii) pausing the print when the top layer of the cavity is reached, iii) manually inserting the component, and iv) resuming the build process. However, the effect of different interfacial materials (due to the presence or absence of a shape converter) and the pause time during the build process on a part’s material properties is not well-understood. Therefore, the tensile strength of 3D-printed embedded specimens with and without shape converters and with different intervals of pause time is tested in this study. The results from this experimental analysis can be useful for the design guidelines for AM with embedded components as they provide an initial understanding of mechanical properties of these parts.

null

['Karnati, S.', 'Hoerchler, J.L.', 'Liou, F.', 'Newkirk, J.W.']

2021-11-02T15:03:15Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89821

eng

2017 International Solid Freeform Fabrication Symposium

Open

['304L', 'stainless steel', 'miniature tensile specimens', 'tensile strength', 'gage length', 'powder bed additive manufacturing']

Influence of Gage Length on Miniature Tensile Characterization of Powder Bed Fabricated 304L Stainless Steel

Conference paper

https://repositories.lib.utexas.edu//bitstreams/628d1ecb-28f8-4008-8d69-0e70d44cfd13/download

University of Texas at Austin

Miniature tensile specimens with varying aspect ratios were fabricated from 304L stainless steel (SS) made using powder bed additive manufacturing (AM) process. The tensile characteristics measured from these specimens were analyzed to assess the impact of gage length. The study found no impact upon varying gage length on yield and ultimate strength measurements. However, a significant impact was observed on strain measurements. This data was also used to perform Weibull statistics to estimate the stochastic performance of the material. Fractography was performed to visually identify the types of flaws. A comparative study with specimens fabricated from cold rolled annealed 304 SS was also performed. The Weibull parameters were used to compare the variability within cold rolled annealed and AM 304L SS. This study indicates miniature tensile testing is a robust characterization technique for obtaining representative material properties.

null

['Saunders, R.', 'Achuthan, A.', 'Iliopoulos, A.', 'Michopoulos, J.', 'Bagchi, A.']

2021-11-11T16:45:40Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90244', 'http://dx.doi.org/10.26153/tsw/17165']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['grain aspect ratio', 'grain size', 'grain loading direction', 'grain shape', 'metal additive manufacturing', 'powder-based additive manufacturing', 'PAM']

Influence of Grain Size and Shape of Mechanical Properties of Metal AM Materials

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f30b3d74-9f84-471d-a419-de4c54b085e3/download

University of Texas at Austin

Metal powder-based additive manufacturing (PAM) typically results in microstructures with a texture and columnar grain structure. The columnar grains can vary greatly in size and shape throughout the microstructure, which can significantly affect the mechanical properties of the resulting part. A previous study developed a microstructurally informed crystal plasticity constitutive model that took into account grain sizes and shapes then showed that grain geometry can influence the prediction of mechanical behavior of the part. In the present work, the influence of grain aspect ratio, size, and loading direction on the resulting mechanical properties of the PAM part are investigated through a parametric study. Results show that considering size and shape effects have the tendency to increase the material yield strength while decreasing the initial strain hardening modulus. Using this knowledge, it may be possible to optimize a PAM microstructure using process parameters to produce a part which exhibit superior yield strength and hardening modulii compared to traditional materials.

null

['Sesseg, Jens P.W.', 'Riedmann, Paul', 'Fischer, Sybille', 'Schmid, Hans-Joachim']

2021-12-01T23:53:13Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90664', 'http://dx.doi.org/10.26153/tsw/17583']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'laser sintering', 'polymer', 'grain size distribution', 'powder rheology', 'polyamide 12']

The Influence of Grain Size Distribution of PA12 on Key Steps of the Polymer Laser Sintering Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4c9b28f7-b081-4ce1-99b6-d30cc113c78c/download

University of Texas at Austin

As the industry pushes for higher resolution laser sintering, finer and finer powders are required. Yet, this also changes the way powders behave during the process. In this project, the influence of finer particles on the dosing and coating process during laser sintering is being investigated. PA12 laser sintering powder without flow additives was sieved to four fractions with grain sizes with a d50 of 42, 54, 61 and 66 µm. These fractions were characterized regarding powder flowability by FT4 powder rheometer. The dosing and coating behavior of these fractions was tested in separate experiments on an EOS P395, where the coating experiments were performed at both RT and 175°C. Furthermore, test jobs were built with the different powder fractions. The larger portion of fines in the finest fraction dominated the powder properties and led to significantly worse powder behavior during the dosing and coating steps, as predicted by analytical measurements.

null

['Thöne, M.', 'Leuders, S.', 'Riemer, A.', 'Tröster, T.', 'Richard, H.A.']

2021-10-06T20:17:39Z

8/22/12

Mechanical Engineering

null

['https://hdl.handle.net/2152/88431', 'http://dx.doi.org/10.26153/tsw/15368']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['heat treatment', 'selective laser melting', 'Ti6Al4V', 'titanium alloys']

Influence of Heat-Treatment of Selective Laser Melting Products - e.g. Ti6Al4V

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ed41d5f2-7453-4bde-9353-da484c5f966c/download

University of Texas at Austin

Usually additive manufactured metal parts are showing a different mechanical behavior compared to conventionally produced parts used the same material. Apart from process-related macroscopic part imperfections (pores, surface roughness, etc.) the microstructure has a decisive influence on the mechanical properties of the materials. Thus, in order to optimize mechanical properties of metal parts a heat treatment for changing microstructures is routinely applied in most production lines to meet the product requirements. By means of the Titanium alloy Ti6Al4V the optimization of the static- and the fracture mechanical behavior by changing the microstructure with a heat treatment after the SLM process is discussed on the present work.

null

['Khalil, Y.', 'Hopkinson, N.', 'Kowalski, A.', 'Fairclough, J.P.A.']

2021-10-27T22:36:35Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89635

eng

2016 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'UHMWPE', 'laser sintering', 'laser power', 'micro computed tomography', 'micro-CT']

Influence of Laser Power of Morphology and Properties of Laser-Sintered UHMWPE

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b7047a15-6479-4b1f-869b-6ca77707898a/download

University of Texas at Austin

Porous structures have unique physical properties(mechanical, density, etc.) that are related to their low density and architecture. These properties open a wide range of potential applications, such as biomedical, packaging, thermal insulation, filtering, food and beverage, pharmaceuticals, automobile, military and aerospace industries [1]. Laser Sintering is an additive manufacturing method that offers many advantages over conventional manufacturing techniques of porous structures with well-defined architectures, controllable pore sizes, excellent reproducibility, higher pore interconnectivities and improved mechanical properties can be produced accurately and rapidly. This study describes the morphological and mechanical characterisations of porous Ultra-High Molecular Weight Polyethylene (UHMWPE) laser sintered parts to gain an insight into the correlation of process parameters and the morphological properties of these parts. Laser power was investigated to control the mechanical properties and porosity of the structures. The fabricated parts were characterised through porosity measurements, three point flexural test and scanning electron microscopy (SEM). X-ray micro-computed tomography (micro-CT) was considered to evaluate the mean internal porosity as well as the size and spatial distribution of pores inside the structure of the UHMWPE parts aiming at a better understanding of the three-dimensional internal morphology of UHMWPE laser-sintered parts. The porosity was then compared with the porosity measured using the helium gas pycnometer method. The results showed a high level of porosity in the UHMWPE laser-sintered parts with a range of 60-65% measured by micro-CT technique and helium gas pycnometer method respectively. There are no significant differences in the results obtained from both techniques and both results fit very well with each other. The results show that flexural strength decreases with an increase in porosity of the sintered parts.

null

['Yarrapareddy, Eswar R.', 'Anderson, Alan J.', 'Sears, James W.']

2020-02-12T15:25:46Z

2004

Mechanical Engineering

null

['https://hdl.handle.net/2152/79937', 'http://dx.doi.org/10.26153/tsw/6963']

eng

2004 International Solid Freeform Fabrication Symposium

Open

Laser Processing

Influence of Laser Processing Parameters on the Corrosion Behavior in 316L Stainless Steel Laser Powder Depositions

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2ec0dcfb-50e3-4f79-bc4d-4a9acf087d9e/download

null

['Xue, Fangkai', 'Boudaoud, Hakim', 'Robin, Guillaume', 'Cruz Sanchez, Fabio A.', 'Daya, El Mostafa']

2023-01-27T13:41:13Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117329', 'http://dx.doi.org/10.26153/tsw/44210']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Fused deposition modeling (FDM)', 'Interface adhesion strength', 'Microstructure', 'Processing']

Influence of layer thickness and nozzle temperature on the interlocking adhesion strength of additive manufactured multi-material interface

Conference paper

https://repositories.lib.utexas.edu//bitstreams/59116e70-d411-4eda-9426-24ad8b12dac7/download

null

Achieving adequate adhesion strength at multi-material interfaces is always a challenge in material extrusion additive manufacturing (MEAM), especially when the materials have very different chemical affinities. This study investigated the adhesion mechanism of multi-material interfaces in MEAM from a micro-geometric perspective. The vertically printed interface was found to have a smooth surface, while the horizontally printed interface had a micro-zigzag interlocking geometry. The formation of this micro-zigzag interlock is due to the switching of extruders during printing, which mechanically reinforces the interface adhesion strength. Using butt-joint tensile test and microscope observation, it was found that the geometry of this zigzag interlock is significantly influenced by the layer thickness, nozzle temperature and extruder offset. By optimizing the layer thickness and nozzle temperature, the interface adhesion strength between dissimilar materials was increased by 58.2% without significantly increasing the printing time or fabrication complexity.

null

['Norrell, J. L.', 'Kandis, .M', 'Bergman, T. L.']

2018-11-16T16:35:23Z

1996

Mechanical Engineering

doi:10.15781/T2WW77K3Q

http://hdl.handle.net/2152/70297

eng

1996 International Solid Freeform Fabrication Symposium

Open

['powder temperatures', 'uncontrolled sintering', 'viscous sintering']

The Influence of Natural Convection and Radiation Heat Transfer on Sintering of Polycarbonate Powders

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3213c2dd-5193-41c8-ada7-ea5f103445c0/download

null

The influence ofsurface radiation and natural convection on sintering of polycarbonate powders processed under non-isothermal conditions is investigated. These modes of heat transfer affect local powder temperatures and thus local sintering rates which in turn influence part growth (uncontrolled sintering). This paper presents a 2-dimensional sintering simulation of powder whose free surface exchanges energy with the surrounding enclosure surfaces. Modeling is accomplished using a commercial finite element code (FIDAP) in conjunction with a model for viscous sintering.

null

['Kummert, C.', 'Diekmann, W.', 'Tews, K.', 'Schmid, H.J.']

2021-11-18T01:21:32Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90390', 'http://dx.doi.org/10.26153/tsw/17311']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['PA6x', 'part microstructure', 'mechanical properties', 'selective laser sintering']

Influence of Part Microstructure on Mechanical Properties of PA6x Laser Sintered Specimens

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7bb58d7d-79cb-4d35-a6a9-631d0bb07eee/download

University of Texas at Austin

The influence of different process parameters on mechanical properties of selectively laser sintered (SLS) parts was investigated in various studies. Until now, the significant differences in mechanical characteristics depending on processing conditions are insufficiently explained but reasons may be found in part microstructure. For this reason, PA6x test specimens with different component properties were printed by changing laser exposure strategies and their microstructure was examined using for example XCT-analysis. PA6x is a comparatively new SLS material which offers outstanding mechanical properties if adequate SLS processing parameters are used. In this study different SLS machines are used by EVONIK and the DMRC, Paderborn University to investigate the relationship between SLS-specific manufacturing conditions, the resulting components microstructure and finally the component properties. The knowledge gained can contribute to a deeper understanding of the process.

null

['Jayanthi, Suresh', 'Hokuf, Bronson', 'Lawton, John']

2018-10-05T17:05:37Z

1995

Mechanical Engineering

doi:10.15781/T2445HX78

http://hdl.handle.net/2152/68715

eng

1995 International Solid Freeform Fabrication Symposium

Open

['sterelithography models', 'photopolymer models', 'UV and thermal cure']

Influence of Post Curing Conditions on the Mechanical Properties of Stereolithographic Photopolymers

Conference paper

https://repositories.lib.utexas.edu//bitstreams/eac4a606-3abb-417c-b4a6-307116271c74/download

null

Post cure methods have always been a critical issue for most of the currently used stereolithography photopolymers. Different post cure conditions can be used to enhance the mechanical and physical properties of the stereolithography models. To better understand the influence of post cure conditions on these material properties, an experimental study evaluating various post cure conditions has been conducted. Ultra-violet, thermal and ultra-sound post curing techniques are investigated and a comparative study is made for one epoxy based photopolymer - Somos™ 6100. Similar results should be attainable for other epoxy based photopolymers.

null

['Slattery, Lauren A.', 'Guckert, Nicole L.', 'Shell, Courtney E.', 'Neptune, Richard R.']

2021-10-06T20:37:38Z

8/22/12

Mechanical Engineering

null

['https://hdl.handle.net/2152/88437', 'http://dx.doi.org/10.26153/tsw/15374']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['selective laser sintering', 'Nylon 11', 'material voids', 'post-build annealing', 'functional energy storage', 'prosthetic devices']

The Influence of Post-SLS-Build Annealing on Nylon 11 Material Properties

Conference paper

https://repositories.lib.utexas.edu//bitstreams/78fa4bc9-7c7b-4d45-a54a-94f224478194/download

University of Texas at Austin

Functional energy storage and return prosthetic and orthotic devices have been manufactured out of Nylon 11 using selective laser sintering due to its high ductility and energy return properties. However, there is concern that material voids caused by incomplete sintering may compromise material properties and lead to premature fracture. Post-build annealing has the potential to eliminate voids caused by incomplete sintering and increase part ductility and strength. The purpose of this study was to post-build anneal Nylon 11 tensile specimens at 1) slightly below their melting temperature, 2) their recrystallization temperature, and 3) their glass transition temperature for two different time durations (12 and 24 hours) to assess the effectiveness of annealing in improving ductility and strength. Specimens annealed at their glass transition temperature had significantly greater percent elongations and lower Young’s moduli than specimens annealed close to their melting or recrystallization temperatures. At each temperature, specimens annealed for shorter durations demonstrated a greater increase in percent elongations and a greater decrease in Young’s moduli. Annealing at the glass transition temperature for 12 hours resulted in the highest percent elongation, although it was not significantly different from the control (unannealed) specimens. However, at these annealing conditions Young’s modulus significantly decreased from the control specimens. Across all annealing conditions, Young’s modulus and percent elongation were found to be negatively correlated. Future work should focus on annealing specimens for additional combinations of temperature and duration to further improve ductility while minimizing the negative effects on part strength.

null

['Gürtler, F.-J.', 'Karg, M.', 'Dobler, M.', 'Kohl, S.', 'Tzivilsky, I.', 'Schmidt, M.']

2021-10-18T21:35:54Z

2014

Mechanical Engineering

null

https://hdl.handle.net/2152/89255

eng

2014 International Solid Freeform Fabrication Symposium

Open

['laser beam melting', 'additive manufacturing', 'metal powder bed', 'parameter optimization', 'melt pool', 'porosity formation', 'OpenFOAM']

Influence of Powder Distribution on Process Stability in Laser Beam Melting: Analysis of Melt Pool Dynamics by Numerical Simulations

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c5815569-349b-48fc-bd8b-3b27afd2a0d3/download

University of Texas at Austin

The occurrence of defects in the additive manufacturing process of laser beam melting in metal powder bed can be reduced through empiric parameter optimization – but knowledge about basic effects like the influence of the composition of the powder layer on the melt pool is still limited. Particle size distribution and powder layer inhomogeneity after layer coating influence melt pool dynamics and may cause defects in the work pieces. This correlation can hardly be analyzed in experiments, so a three-dimensional transient numerical simulation model is used. The model is based on the continuity equation, the heat equation and the Navier-Stokes equation. Therefore, the finite-volume method capabilities in OpenFOAM are used. The free surfaces of the multi-phase system are calculated using the volume of fluid method. The powder beds have unimodal or bimodal distributions without random effects in the particle composition. Their density and thermal conductivity is adapted to reality. The investigations of the melt pool and the porosity formation demonstrate an advantage of more and smaller particles in the powder for compensation of defects in the powder bed, similar to the results of the experiments.

null

['Sinico, M.', 'Cogo, G.', 'Benettoni, M.', 'Calliari, I.', 'Pepato, A.']

2021-11-18T01:01:11Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90382', 'http://dx.doi.org/10.26153/tsw/17303']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['particle size distribution', 'powder particle', 'printability', 'pure copper', 'Cu', 'selective laser melting']

Influence of Powder Particle Size Distribution on the Printability of Pure Copper for Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4a19bc20-f802-4332-adc9-5b79c2c54b96/download

University of Texas at Austin

This work investigates the use of fine Cu powder, with ~ 20 vol% smaller than 15 μm size, for the selective laser melting process. Cubes reaching > 98 % density are produced at relative low laser output (175 W) and characterized. After the selection of a proper combination of laser scan parameters, the properties of fabricated parts are briefly studied through profilometry and tensile tests. Finally, a voluminous demo component for high-energy physics is manufactured to stress-test the employed SLM machine. Even though unmolten particles and lack of fusion defects are still present in the produced specimens, the investigated approach confirms that powder selection can have a huge influence on the processability of materials with high reflectivity towards near-infrared irradiation.

null

['Binder, Maximilian', 'Yücel, Olgu', 'Bareth, Thomas', 'Schlick, Georg', 'von Müller, Alexander', 'You, Jeong-Ha', 'Buschmann, Birger', 'de Luca, Riccardo', 'Fanelli, Pierlugi', 'Seidel, Christian']

2023-01-26T14:37:28Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117307', 'http://dx.doi.org/10.26153/tsw/44188']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Additive manufacturing', 'High-Temperature Laser-based Powder Bed Fusion', 'Tungsten', 'Refractory Metal']

Influence of Powder Properties and Process Parameters on the High Temperature PBF-LB/M Manufacturability of Filigree Tungsten Components

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0f7a2ad4-64db-42ee-956b-13a3c3cdab36/download

null

The production of complex lattice structures made of pure tungsten can be of great interest for potential applications in various industrial sectors such as energy technology or medical devices. One example is the plasma-facing armour of so-called limiter components in nuclear fusion power reactors, where the tungsten lattice armour is supposed to withstand extreme heat flux loads up-on transient plasma events.. The reliability of the tungsten armour is hence an important requirement for the sustainable operation of fusion power reactors [1,2]. Tungsten is difficult to process to a satisfactory degree due to its high melting point, its hardness as well as its susceptibility to cracking. Therefore, this paper presents the manner in which tungsten can be processed into fine lattice structures by means of high- temperature laser-based powder bed fusion. It also explains to what extent the used metal powder and the laser-exposure strategy have an influence on pores and component defects. It is shown how particle size distribution and sphericity of the powders have a major impact on the basic processability of the material. Furthermore, it presents to what extent the laser exposure parameters, such as the laser hatch distance, can have an influence on the resulting density of the material and which methods are used to determine the actual material density of lattice cubes in the first place. Finally, measurements of the electrical conductivity of the fabricated AM structures are presented, as this is of interest with respect to many other areas of application.

null

['Yamauchi, Yuki', 'Niino, Toshiki', 'Kigure, Takashi']

2021-11-04T13:48:30Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89959

eng

2017 International Solid Freeform Fabrication Symposium

Open

['geometry', 'part quality', 'process time', 'geometry', 'laser sintering', 'low temperature']

Influence of Process Time and Geometry on Part Quality of Low Temperature Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/542e02b6-c66d-4ee9-ad99-e5d099ad3860/download

University of Texas at Austin

The authors are developing a novel laser sintering process that prevents parts from warping by anchoring them to a rigid base plate. Since the powder bed temperature of the process is normally lower than in the standard process, the laser is required to supply more energy in the novel process, namely low temperature process. Accordingly, the part quality is more sensitive to laser parameters. Additionally, accumulation and dispersion of energy which is supplied by the laser through layers plays an important role in the consolidation of the powder. Thus, in low temperature process, parameter relating part geometry and time affects the part quality more than in standard high temperature process. In this research, the influence of part size and process time per layer on the density of parts as a primary index of part quality is investigated. Density decreases as the process time per layer increases. With respect to part size, density increases as parts become larger.

null

['King, Bruce H.', 'Morissette, Sherry L.', 'Denham, Hugh', 'Cesarano, Joseph', 'Dimos, Duane']

2019-02-22T20:11:10Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73473', 'http://dx.doi.org/10.26153/tsw/623']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['polymers', 'ceramics']

Influence of Rheology on Deposition Behavior of Ceramic Pastes in Direct Fabrication Systems

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9c3c327c-fc5c-4c38-8831-0c4f20f74067/download

null

Rheology and deposition behavior offour commercially available thick-film inks and an aqueous alumina slurry were investigated using two different slurry-based deposition systems. The first ofthese deposition systems, a Micropen, is a commercially available system designed for the deposition of electronic thick film circuits. The second system, referred to as a Robocaster, is a developmental system designed to build thick or structural parts. Slurry rheology was seen to have a minor effect on deposition behavior and the bead shape when deposited using the Micropen. The deposition behavior was instead dominated by drying rate; too rapid of a drying rate led to excessive clogging of the tip. Slurry rheology had a greater impact on the shape of beads deposited using the Robocaster. Highly viscous slurries yielded initially well-defined beads, whereas beads deposited using fluid slurries spread quickly. In both cases, significant spreading occurred with time. These observations only held for slurries with slow drying rates. It was observed that very fluid slurries produced well-defined beads when the drying rate was suitably high.

null

['Ajinjeru, Christine', 'Kishore, Vidya', 'Chen, Xun', 'Lindahl, John', 'Sudbury, Zeke', 'Hassen, Ahmed Arabi', 'Kunc, Vlastimil', 'Post, Brian', 'Love, Lonnie', 'Duty, Chad']

2021-10-27T22:06:31Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89629

eng

2016 International Solid Freeform Fabrication Symposium

Open

['rheology', 'big area additive manufacturing', 'processing conditions', 'amorphous thermoplastics']

The Influence of Rheology on Melt Processing Conditions of Amorphous Thermoplastics for Big Area Additive Manufacturing (BAAM)

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0e1884ec-0c5f-4740-8825-c0d19103029f/download

University of Texas at Austin

This paper evaluates the influence of the rheological behavior of thermoplastics used in Big Area Additive Manufacturing (BAAM) on the melt processing conditions. An extensive rheological characterization has been conducted of two base resins; acrylonitrile butadiene styrene (ABS) and polyphenylsulfone (PPSU) as well as their composites containing reinforcing fibers. It was found that the unique processing conditions for each material is highly dependent on the rheological properties of these polymeric systems. A method is presented for considering rheological characteristics when selecting candidate materials suitable for the BAAM system and in developing processing bounds to achieve required material properties for applications such as high temperature tooling and composite structures.

null

['Emminghaus, N.', 'Bernhard, R.', 'Hermsdorf, J.', 'Overmeyer, L.', 'Kaierle, S.']

2024-03-25T23:59:33Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124349', 'https://doi.org/10.26153/tsw/50957']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['additive manufacturinng', 'Ti-6Al-4V', 'laser powder bed fusion', 'silane', 'powder recycling']

Influence of Silane-doped Argon Processing Atmosphere on Powder Recycling and Part Properties in L-PBF of Ti-6Al-4V

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1babedd3-a973-4f2f-a1be-e74b80073d34/download

University of Texas at Austin

In the additive manufacturing of metal powders, the residual oxygen in the processing atmosphere plays a crucial role, especially in highly reactive materials like titanium alloys. Besides oxidation of the built parts, it leads to oxygen pick-up into the unmolten powder. Since oxidized particles cannot be removed during recycling, the powder properties deteriorate after multiple uses. In this work, Ti-6Al-4V powder was processed under conventional argon atmosphere (residual oxygen content < 0.01 vol%) as well as silane-doped argon atmosphere (< 0.001 vol% silane in argon). The silane-doping leads to a residual oxygen content of < 10-20 vol%. The powder was sieved and used 5 times for each atmosphere. The powder properties morphology, chemical composition and flowability were analyzed for virgin as well as reused powder. Furthermore, the roughness and relative density of the built parts were evaluated. It was hypothesized that oxygen-free production improves recyclability and thus resource efficiency.

null

['Kelley, J.P.', 'Newkirk, J.W.', 'Bartlett, L.N.', 'Sparks, T.', 'Isanaka, S.P.', 'Alipour, S.', 'Liou, F.']

2024-03-26T00:02:23Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124350', 'https://doi.org/10.26153/tsw/50958']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['laser-dirrected energy deposition', 'alloy design', 'robustness', 'sensitivity analysis', 'high-strength low-alloy steel', 'in-situ alloying', 'powder blend']

INFLUENCE OF STEEL ALLOY COMPOSITION ON THE PROCESS ROBUSTNESS OF AS-BUILT HARDNESS IN LASER-DIRECTED ENERGY DEPOSITION

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1e183dbc-1993-45cd-b4f1-ddfd185c298d/download

University of Texas at Austin

To ensure consistent quality of additively manufactured parts, it is advantageous to identify alloys which can meet performance criteria while being robust to process variations. Toward such an end, this work studied the effect of steel alloy composition on the process robustness of as-built hardness in laser-directed energy deposition (L-DED). In-situ blending of ultra-high-strength lowalloy steel (UHSLA) and pure iron powders produced 10 alloys containing 10-100% UHSLA by mass. Thin-wall samples were deposited, and the hardness sensitivity of each alloy was evaluated with respect to laser power and interlayer delay time. The sensitivity peaked at 40-50% UHSLA, corresponding to phase fluctuations between lath martensite and upper bainite depending on the cooling rate. Lower (10-20%) or higher (70-100%) alloy contents transformed primarily to ferrite or martensite, respectively, with auto-tempering of martensite at lower cooling rates. By avoiding martensite/bainite fluctuations, the robustness was improved.

null

['Rietzel, D.', 'Drexler, M.', 'Kühnlein, F.', 'Drummer, D.']

2021-10-04T21:31:05Z

8/17/11

Mechanical Engineering

null

['https://hdl.handle.net/2152/88354', 'http://dx.doi.org/10.26153/tsw/15293']

eng

2011 International Solid Freeform Fabrication Symposium

Open

['powder based additive manufacturing', 'beam based additive manufacturing', 'laser sintering', 'mask sintering', 'influencing paramters', 'part properties']

Influence of Temperature Fields on the Processing of Polymer Powders by Means of Laser and Mask Sintering Technology

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b2910f4c-7224-49a5-b30a-b434f6533a6c/download

University of Texas at Austin

Besides their high potential for individual series-production, powder and beam based additive manufacturing technologies, like laser and mask sintering, are in general still restricted to prototyping applications. This is a result of multiple limitations concerning part properties (e.g. mechanical and geometrical), their insufficient reproducibility due to transient thermal conditions and the limited range of available materials. The main focal point of this paper is to show the influencing parameters (e.g. temperature fields in the building chamber) of powder-based thermoplastic processing technologies on part properties, like porosity and surface quality, and on the processability of further new polymers (e.g. polypropylene and polyoxymethylene).

null

['Huseynov, Orkhan', 'Fidan, Ismail']

2023-01-20T16:53:56Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117266', 'http://dx.doi.org/10.26153/tsw/44147']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Fiber Reinforced Additive Manufacturing', 'Short Carbon Fiber', 'Fused Filament Fabrication', 'Thermal Properties', 'Thermal Characterization']

Influence of the Different Matrix Materials on the Thermal Properties of Short Carbon Fiber Reinforced Composites

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5e26cade-4c20-42d4-9f52-6c7236b07121/download

null

A considerable amount of literature has been published on the thermal properties of the short carbon fiber reinforced composites (SCFRC). However, no study has focused on the effect of the various matrix materials on the thermal properties of the SCFRC. The aim of this study is to investigate the thermal propertiesof neat and composite PETG, PC/PBT, ABS, and Nylon filled with short carbon fibers. In order to do this, thermal conductivity and thermal diffusivity of the samples were measured. Thermogravimetric and differential scanning calorimetry analyses were performed to study degradation, glass transition temperature, and specific heat value. The findings of the study are essential in reporting the relationships between the SCFRCs and commonly used polymer materials.

null

['Spierings, A.B.', 'Herres, N.', 'Levy, G.']

2021-09-30T15:36:34Z

9/23/10

Mechanical Engineering

null

['https://hdl.handle.net/2152/88265', 'http://dx.doi.org/10.26153/tsw/15206']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['Additive Manufacturing', 'selective laser melting', 'surface quality', 'powder materials']

Influence of the Particle Size Distribution on Surface Quality and Mechanical Properties in Additive Manufactured Stainless Steel Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2b78555b-63e0-4b0b-ae00-5686cf20c3a1/download

University of Texas at Austin

A recent study confirmed that the particle size distribution of a metallic powder material has a major influence on the density of a part produced by SLM. Although it is possible to get high density values with different powder types, the processing parameters have to be adjusted accordingly, affecting the process productivity. However, the particle size distribution does not only affect the density but also the surface quality and the mechanical properties of the parts. Therefore, this study compares three different particle size distributions depending on the laser scan velocity and two layer thicknesses of 30μm and 45μm. By using an optimized powder material a low surface roughness can be obtained. A subsequent blasting process can further improve the surface roughness for all powder materials used in this study although this does not change the ranking of the powders with respect to the resulting surface quality.

null

['Meyer, L.', 'Wegner, A.', 'Witt, G.']

2021-11-04T13:32:54Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89954

eng

2017 International Solid Freeform Fabrication Symposium

Open

['laser sintering', 'packing density', 'translation', 'contra-rotating coating', 'ratio']

Influence of the Ratio Between the Translation and Contra-Rotating Coating Mechanism on Different Laser Sintering Materials and Their Packing Density

Conference paper

https://repositories.lib.utexas.edu//bitstreams/24321868-a543-4f9b-a942-76dd4569a480/download

University of Texas at Austin

An initial study about the advanced machine parameters and their impact on the packing density of different laser sintering materials was conducted on a self-developed laser sintering machine. Usually, on commercial machines, the ratio between the translational and contra-rotatory movement of the roller is fixed. The standard ratio is established for polyamide 12, but new materials, such as polyamide 6 or polybutylene terephthalate, need adjustable parameters to find optimized composition coating results. In the testing machine, the contra rotating roller can be replaced by a coating blade to generate the powder layers. In Addition to the tests with the roller, two different shapes of coating blades were tested. This allows a comparison between both commercial coating systems in laser sintering machines.

null

['Lubkowitz, V.', 'Scherer, T.', 'Schulze, V.', 'Zanger, F.']

2024-03-26T05:39:27Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124359', 'https://doi.org/10.26153/tsw/50967']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['AlSi10Mg', 'TiC nanoparticles', 'laser power bed fusion', 'additive manufacturing']

Influence of TiC-Nanoparticles on the material properties of AlSi10Mg manufactured by Laser Powder Bed Fusion

Conference paper

https://repositories.lib.utexas.edu//bitstreams/29795b4c-3824-48ff-b223-b66c467514d3/download

University of Texas at Austin

Additive manufacturing enables the production of complex lightweight components. However, the poor use of atomized metal powders poses a challenge in terms of ensuring flowability and new high-strength aluminum alloys are still lacking. Some investigations show that the mechanical properties of AlSi10Mg can be improved by adding TiC nanoparticles. This study aims to determine if the influence of small amounts of TiC additions, which are normally used to improve the flowability of fine powders, is also sufficient to improve the mechanical properties. It was found that the addition of 0.46 wt% TiC-Nanoparticles with a size of 50 nm led to a homogeneous grain size distribution and an increase of 16 % in yield strength, but a 32 % decrease in elongation compared to pure AlSi10Mg. Further, a strong median grain size reduction from 5.08 to 2.74 µm could be observed by adding 0.96 wt% of TiC-Nanoparticles.

null

['Gu, Hengfeng', 'Gong, Haijun', 'Pal, Deepankar', 'Rafi, Khalid', 'Starr, Thomas', 'Stucker, Brent']

2021-10-11T20:40:39Z

2013

Mechanical Engineering

null

['https://hdl.handle.net/2152/88638', 'http://dx.doi.org/10.26153/tsw/15572']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['energy density', 'metal selective laser melting', 'selective laser melting', '17-4PH stainless steel', 'porosity', 'microstructure']

Influences of Energy Density on Porosity and Microstructure of Selective Laser Melted 17- 4PH Stainless Steel

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ac003b41-d9c3-49bb-bb4a-0c9e888c54f5/download

University of Texas at Austin

Energy density, which directly impacts the properties of as-built parts, is a key factor in the metal selective laser melting (SLM) process. This paper studies the influences of energy density on porosity and microstructure of SLM 17-4PH stainless steel parts. Experiments were carried out by varying processing parameters to change energy density. Porosity was estimated using the Archimedes method and image analysis. Microstructures were investigated through optical and electron microscopy. The experimental results were discussed regarding porosity formation and microstructure characterization.

null

['Momenzadeh, Niknam', 'Berfield, Thomas A.']

2021-11-11T15:58:20Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90226', 'http://dx.doi.org/10.26153/tsw/17147']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['polyvinylidene fluoride', 'piezoelectric properties', 'fourier transform infrared spectroscopy', 'fused filament fabrication']

Influences of Printing Parameters on Semi-Crystalline Microstructure of Fused Filament Fabrication Polyvinylidene Fluoride (PVDF) Components

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c2088947-d06b-4a5b-baa9-804f5f345c39/download

University of Texas at Austin

Piezoelectric polymers have garnered wide interest for sensing, actuation, and energy harvesting applications due to their unique combination of high strain tolerance and electro-mechanical coupling. Compared to other piezoelectric polymers, polyvinylidene fluoride (PVDF) and its copolymer and terpolymer variations demonstrate some of the strongest piezoelectric responses. One of the primary challenges associated with PVDF is that its piezoelectric response is highly dependent on its microstructure, which varies greatly with manufacturing-associated stresses. This work investigates Fused Filament Fabrication (FFF) of PVDF polymers, and the effects of processing parameters such as layer thickness, infill pattern, infill density and nozzle diameter on its microstructure development. Fourier Transform Infrared Spectroscopy (FTIR) measurements are used to assess the relative phase content of the semi-crystalline microstructure arrangement primary related with significant piezoelectric response in PVDF (β-phase).

null

['Steinberger, J.', 'Shen, J.', 'Göpfert, J.', 'Gerner, R.', 'Daiber, F.', 'Manetsberger, K.', 'Fersti, S.']

2019-09-23T16:11:58Z

2000

Mechanical Engineering

null

['https://hdl.handle.net/2152/75952', 'http://dx.doi.org/10.26153/tsw/3051']

eng

2000 International Solid Freeform Fabrication Symposium

Open

Inhomogeneous

Inhomogeneous Shrinkage of Polymer Materials in Selective Laser Sintering 298

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4b728122-aea4-49a9-ac62-197091515cd7/download

null

It is well known that the laser beam of an SLS machine can be controlled almost exactly. The inaccuracy of the mechanical movements of the machines is also much lower than the actual errors of the SLS parts. How can we explain this discrepancy? One answer is the temperature inhomogeneity in the build field and in the part bed. In this article the effect of temperature dependent volume relaxation of pre-sintered polymer parts on the inaccuracy of the SLS process will be discussed. The investigation shows that it depends on the temperature, pressure and time. Measurements of the temperature distribution in an SLS part bed were carried out. By determining coordinate-dependent scaling factors, an empirical method to compensate this nonlinear shrinkage is presented in this article.

null

['Barrow, Stacia L.', 'Bourell, David', 'Evajs, Scott']

2020-02-13T19:14:39Z

8/16/04

Mechanical Engineering

null

['https://hdl.handle.net/2152/79962', 'http://dx.doi.org/10.26153/tsw/6987']

eng

2004 International Solid Freeform Fabrication Symposium

Open

High-temperature infiltration

An Initial Assessment of Infiltration Material Selection for Selective Laser Sintered Preforms

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d189726b-4814-425a-8568-4535c8a392d3/download

null

High-temperature infiltration is an important process that is used to add strength to skeletal microstructures. In this study, particulate metal matrix composites (MMCs) are fabricated. MMCs are applied in a wide variety of industries, including military, aircraft, tooling and automotive. In this paper, various materials for infiltrating selective laser sintered (SLS) silicon carbide and titanium carbide preforms are considered based on fundamental knowledge of SLS and infiltration mechanics. Proposed infiltrant materials systems include an aluminum-silicon alloy infiltrant and a silicon carbide preform, ductile iron infiltrated into a titanium carbide preform, and commercially pure silicon infiltrated into a silicon carbide preform. The first two infiltrants are considered because they add ductility to the brittle silicon carbide or titanium carbide part, thus broadening the range of applications. They also will model a broader field of possible infiltrants, including magnesium and iron-based materials, (e.g., steel). Silicon is investigated because it adds strength to silicon carbide, is robust at high temperatures, and has a comparable coefficient of thermal expansion. Presented is a feasibility assessment of these systems based on infiltration theory.

null

['Collins, Daniel S.', 'Turner, Cameron']

2021-12-07T17:20:27Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90727', 'http://dx.doi.org/10.26153/tsw/17646']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['print heating', 'radiative heat transfer', 'fused deposition modeling', 'Arizona State University']

Initial Development of a Simulation Model of a Radiation-based Print Heating System for Fused Deposition Modeling

Conference paper

https://repositories.lib.utexas.edu//bitstreams/302ad41e-a084-47f6-a1e4-ba190ead60b2/download

University of Texas at Austin

Fused Deposition Modeling (FDM) has become a standard 3D printing process for thermoplastics. However, the process results in different strength characteristics along each cardinal direction of a part attributed to different bonding times between filaments. The resulting anisotropic characteristics are an obstacle when considering FDM printed parts for mechanical purposes. Work at Arizona State University has demonstrated a method using laser-based heating to achieve improved polymer bonding without loss of dimensional accuracy. In this research we consider the possibilities of reheating the filament via radiative heat transfer to achieve the same outcome. By exploring the approach in simulation and conducting confirmation experiments, we evaluate the ability to increase strength in FDM components by post-deposition controlled radiative heat-transfer.

null

['Lewis, Adam', 'McElroy, Austin', 'Milner, Thomas', 'Fish, Scott', 'Beaman, Joseph']

2021-11-03T22:05:47Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89947

eng

2017 International Solid Freeform Fabrication Symposium

Open

['optical coherence tomography', 'part porosity', 'selective laser sintering', 'laser power']

Initial Investigation of Selective Laser Sintering Laser Power vs Part Porosity Using In-Situ Optical Coherence Tomography

Conference paper

https://repositories.lib.utexas.edu//bitstreams/36048083-89b3-4de3-b2de-679c9783a34c/download

University of Texas at Austin

Additional types of process sensors could be useful in further improving consistency of Selectively Laser Sintered (SLS) parts. Optical Coherence Tomography (OCT) has shown promise as a new SLS process sensor which can yield depth resolved data not attainable with conventional sensors. This study investigates the use of OCT as a tool to determine part porosity. Various laser powers were used during the build and the in-situ OCT data corresponding to the various laser powers are compared. The finished part was then imaged using X-ray Computed Tomography (XCT). Porosity data was obtained and is compared with the OCT data.

null

['Karapatis, N. P.', 'Griethuysen, J.-P. S. van', 'Glardon, R.']

2018-11-30T16:53:42Z

1997

Mechanical Engineering

doi:10.15781/T26D5PX29

http://hdl.handle.net/2152/70599

eng

1997 International Solid Freeform Fabrication Symposium

Open

['CAD', '3D Systems']

Injection Molds Behavior and Lifetime Characterization

Conference paper

https://repositories.lib.utexas.edu//bitstreams/047e4d6c-3fee-43f8-bf22-535c8a0a19cd/download

null

This paper presents the concept of a standard method used to determine the durability of injection molds. In particular, some Rapid Tooling molds are less resistant to abrasive plastics than conventional steel molds. Some evidence of wear in a conventional mold is given, and a specific mold is designed for this test; polymer materials are defined and the test methodology is outlined. Numerical simulation is utilized to show the areas ofthe mold subject to high shear stresses.

null

['Miers, John C.', 'Zhou, Wenchao']

2021-10-21T18:18:34Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89417

eng

2015 International Solid Freeform Fabrication Symposium

Open

['inkjet printing', 'megahertz frequency', 'droplet formation']

Inkjet Printing at Megahertz Frequency

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f8d75d85-3930-4650-9c16-f7c237bcebc0/download

University of Texas at Austin

Inkjet printing enables more efficient, economic, scalable manufacturing for a wider variety of materials, than other traditional additive techniques. However, the jetting frequency of commercial droplet-on-demand inkjet techniques is mostly limited to ~10 kHz. This paper presents an investigation of the possibility of jetting at megahertz frequencies in order to boost the productivity of inkjet by ~100 times. The key to this problem is rooted in droplet formation dynamics, a subject that has been extensively studied for over 300 years. Hence, the focus of this paper is to understand the limitations of generating droplets at a megahertz frequency and explore possible solutions for overcoming these limitations. The paper begins with a review of literature on the dynamics of droplet formation. A numerical model is then developed for the simulation of droplet formation dynamics. The numerical model is validated against available experimental data from the literature. Aided by insights gained from scaling analysis, the validated model is then used to study the effects of different process parameters on high frequency jetting. The study finds energy density input to the nozzle is the key to achieve megahertz frequency printing.

null

['Kolb, Cara G.', 'Mareddy, Harish R.', 'Guenter, Florian J.', 'Zaeh, Michael F.']

2021-11-16T16:39:56Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90340', 'http://dx.doi.org/10.26153/tsw/17261']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['inkjet printing', 'lithium-ion cell', 'multi-material processing', 'surface structuring']

Inkjet Printing of Geometrically Optimized Electrodes for Lithium-Ion Cells: A Concept for a Hybrid Process Chain

Conference paper

https://repositories.lib.utexas.edu//bitstreams/bdeed7ed-2640-4516-bbff-bc32ac2f393b/download

University of Texas at Austin

Lithium-ion batteries have proven to be reliable energy storage devices for portable and stationary electrical consumers because they possess a high energy and power density. Nevertheless, modern applications require more demanding performance characteristics. Electrodes with a structured surface design, which improves current densities and therefore enables faster charging and discharging, promise to reach the required cell characteristics. Conventionally, structured electrodes are produced by subtractive post-treatment, such as laser processing, which only allows structures of limited complexity. This paper demonstrates a novel approach using inkjet printing to produce electrodes with interlocked structures of high geometrical complexity. A concept for a hybrid process chain that combines the additive process with subtractive and further manufacturing technologies is presented. In addition, a selection of geometrically optimized electrodes is shown. This hybrid process chain has the potential to create functional electrodes by multi-material processing of liquid and powdery raw materials.

null

['Begines, B.', 'Hook, A.L.', 'Wildman, R.D.', 'Tuck, C.J.', 'Alexander, M.R.']

2021-10-21T20:54:54Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89445

eng

2015 International Solid Freeform Fabrication Symposium

Open

['bacterial resistance', 'bacterial attachment', 'inkjet printing', 'printability', 'medical devices', 'bacterial infections']

Inkjet Printing of Materials with Resistance to Bacterial Attachment

Conference paper

https://repositories.lib.utexas.edu//bitstreams/39f23b65-7f62-4bab-a69a-14e5d4abee0b/download

University of Texas at Austin

Biofilm formation on the surface of medical devices is a major source of health-care associated infections. The discovery of new materials that inherently avoid formation of such biofilms on their surface points the way to the fabrication of biofilm resistant devices, with the consequent reduction in the incidence rate of device centred infections and therefore a reduction in suffering and costs for health-care systems. Drop on Demand (DOD) Three Dimensional (3D) Inkjet Printing presents higher versatility than common techniques for printing biomaterials. One of the main representations of this enhanced versatility is polymerisation post-jetting, which provides a great range of printable polymers. The combination of such materials with inkjet printing could revolutionise the biomedical industry. In this paper, the printability of four acrylates with resistance to bacterial attachment was assessed using the printability indicator or Z parameter. Three of the materials showed a value of Z within the printability range. The remainder displayed a Z value higher than the maximum suggested. However, this material was ejected with stability using a complex waveform designed for low viscosity inks. Drop spacing was optimised for each ink using PET and glass as substrates. The combination of printability optimisation together with ideal drop spacing allowed the construction of 3D structures of three of the four inks that were tested.

null

['Kuhn, Joshua', 'Green, Matthew', 'Bashyam, Sanjai', 'Seepersad, Carolyn Conner']

2021-10-19T15:21:39Z

2014

Mechanical Engineering

null

https://hdl.handle.net/2152/89297

eng

2014 International Solid Freeform Fabrication Symposium

Open

['3D printing', 'design for 3D printing', 'automatic part removal system']

The Innovation Station: A 3D Printing Vending Machine for UT Austin Students

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8b6d924f-1647-4ec4-9ebe-12929c1f996c/download

University of Texas at Austin

The Innovation Station is designed to provide on-demand, web-enabled 3D printing securely in a public space. The overarching goal is to lower the barriers to 3D printing at a university, to facilitate innovation and creativity, and to inspire future engineers. Both hardware and software innovations were required to realize this capability. From the hardware side, we invented a process to automatically remove parts from the 3D printer and sweep them into a bin from which users can retrieve them without directly accessing the 3D printer. From the software side, in partnership with the Faculty Innovation Center (FIC) at UT Austin, we created a web portal that allows students to upload parts remotely and access detailed directions for creating parts. It also allows administrators to remotely manage the queue and initiate builds. Together, the hardware and the software innovations enable printing multiple jobs continuously without user intervention and remote cancellation of jobs. Plans for the entire station, both hardware and software, are intended to be open source, with a startup cost of less than $4,000 for recreating the station at a new location.

null

['Lin, Feng', 'Zhang, Lei', 'Zhang, Ting', 'Wang, Jia', 'Zhang, Renji']

2021-10-05T15:32:43Z

2012

Mechanical Engineering

null

['https://hdl.handle.net/2152/88392', 'http://dx.doi.org/10.26153/tsw/15331']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'rapid prototyping manufacturing', 'solid freeform fabrication', 'innovative education']

Innovative Education in Additive Manufacturing in China

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b8e63641-0ab6-4770-853a-e77fd890528f/download

University of Texas at Austin

Beginning in 1992, China began to conduct research on additive manufacturing (AM) (i.e., rapid prototyping manufacturing or solid freeform fabrication). These studies included three main areas: processes, equipment, and applications in different fields. At the same time, various educational initiatives in AM were also begun. Regarding the first area, a number of courses related to AM are now being offered in universities and colleges, and not just in those that have already developed research programs on AM, such as Tsinghua University, Xi'an Jiaotong University, Huazhong University of Science and Technology, and South China University of Technology, as well as some higher vocational schools. Owing to the orientation of these colleges and schools, their focus tends to be on the practical applicability of the courses they offer. In addition to the lectures they offer, all of these universities and colleges are equipped with a laboratory or resources for experiments, and have brought in equipment on which students can practice operating software (3D CAD. etc.) and make prototypes of their own design. Along with the development of AM research in China, the proportion of equipment in Chinese production is increasing as well. Moreover, these courses offer lectures, employ Ph.D. students as teaching assistants for undergraduate or junior college students, and also offer training related to creative design and manufacturing for postgraduates. This training has produced good results, in that it requires postgraduates to combine what they have learnt during lectures with their own research. In addition, associations and companies have played an important role in the development of AM in China by interacting with society and offering a number of seminars and workshops. There are many companies that offer courses for people with specific interests, and courses for engineers and technicians have created a boom in AM in China’s automobile industry. A number of associations and companies have even jointly organized design competitions in vocational schools. When students participate in these competitions they become familiar with the advanced technology of AM, an experience that is very important for their future work.

null

['Almeida, P.M. Sequeira', 'Williams, S.']

2021-09-29T22:31:37Z

2010

Mechanical Engineering

null

['https://hdl.handle.net/2152/88221', 'http://dx.doi.org/10.26153/tsw/15162']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['Wire + Arc Additive Layer Manufacture (WAALM)', 'Additive Layer Manufacturing (ALM)', 'Cold Metal Transfer (CMT)', 'Ti-6Al-4V', 'Systematic Experimental Approach (SEA)', 'high deposition rate', 'Buy-to-Fly']

Innovative Process Model of Ti-6Al-4V Additive Layer Manufacturing Using Cold Metal Transfer (CMT)

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8173734a-71ee-4c28-aa8e-a7cc2635a51c/download

University of Texas at Austin

New approaches to modern manufacture have emerged from Additive Layer Manufacturing (ALM) technologies over the last 25 years. These approaches provide form, fit and function to a wide range of metallic alloys and components. Wire + Arc Additive Layer Manufacture (WAALM) has gained the interest of the research community in recent years due to its high deposition rate and efficiency (100%). The technique has been presented to the aerospace manufacturing industry as a unique low cost solution for large structural components manufacture. With this process product development time, capital investment and “Buy-to-Fly” ratios can be significantly improved. One of the greatest challenges of WAALM systems is the control algorithms needed to predict optimum welding parameters in order to achieve a specific target wall width/height requirement, and maximum deposition efficiency. This paper describes a process model for multilayer Ti-6Al-4V deposition using the Gas Metal Arc Welding based process of Cold Metal Transfer. The process model is based on a Systematic Experimental Approach carried out using a regression analysis. The mathematical relationships obtained are ready to use in future large scale “intelligent” WAALM controllers.

null

['Koo, J. H.', 'Pilato, L.', 'Wissler, G.', 'Cheng, J.', 'Ho, W.', 'Nguyen, K.', 'Lao, S.', 'Cummings, A.', 'Ervin, M.']

2020-02-20T20:12:35Z

2005

Mechanical Engineering

null

https://hdl.handle.net/2152/80048

eng

2005 International Solid Freeform Fabrication Symposium

Open

rapid manufacturing

Innovative Selective Laser Sintering Rapid Manufacturing using Nanotechnology

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e07b8363-e24a-4243-a974-289b4ae9f648/download

null

The objective of this research is to develop an improved nylon 11 (polyamide 11) polymer with enhanced flame retardancy, thermal, and mechanical properties for selective laser sintering (SLS) rapid manufacturing (RM). A nanophase was introduced into nylon 11 via twin screw extrusion to provide improved material properties of the polymer blends. Atofina (now known as Arkema) RILSAN® nylon 11 injection molding polymer pellets was used with three types of nanoparticles: chemically modified montmorillonite (MMT) organoclays, nanosilica, and carbon nanofibers (CNF) to create nylon 11 nanocomposites. Wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM) were used to determine the degree of dispersion. Fifteen nylon 11 nanocomposites and control nylon 11 were fabricated by injection molding. Flammability properties (using a cone calorimeter with a radiant flux of 50 kW/m2 ) and mechanical properties such as tensile strength and modulus, flexural modulus, elongation at break were determined for the nylon 11 nanocomposites and compared with the baseline nylon 11. Based on flammability and mechanical material performance, five polymers including four nylon 11 nanocomposites and a control nylon 11 were cryogenically ground into fine powders for SLS RM. SLS specimens were fabricated for flammability, mechanical, and thermal properties characterization. Nylon 11-CNF nanocomposites exhibited the best overall properties for this study.

null

['Plant, R.', 'Chang, S.', 'Hague, R.', 'Tuck, C.', 'Wildman, R.']

2023-04-05T13:36:57Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117771', 'http://dx.doi.org/10.26153/tsw/44650']

eng

2022 International Solid Freeform Fabrication Symposium

Open

packaging

Inserting Components into Geometries Constructed onto a Non-Standard Substrate for Electronics Packaging

Conference paper

https://repositories.lib.utexas.edu//bitstreams/cdc9381a-74a4-46ce-b8d3-6549138e9233/download

null

Additive manufacturing (AM) has matured from its initial concept as a prototyping technique to an industrial manufacturing process. Consequently, AM processes must meet relevant standards for an increasing number of applications. Here, we investigate inserting components into geometries constructed onto a silicon nitride substrate, using stereolithography (SLA), for the purpose of electronics packaging. Compared to conventional processes, SLA avoids high temperatures and stresses while permitting much greater flexibility to arrange components in three dimensions. This facilitates an increased feature density and the construction of packages for use in complex spaces. A characteristic of interest to this application, is the SLA material-substrate interaction and the resulting quality of adhesion. The adhesion mechanism between SLA and silicon nitride is investigated and substantially enhanced by a pre-treatment process. A process for then inserting large and complex geometries and components into the SLA build process is identified and compliance of the product with relevant standards is reviewed.

null

['Jameekornkul, P.', 'Wang, J.', 'Panesar, A.']

2023-04-05T17:17:19Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117782', 'http://dx.doi.org/10.26153/tsw/44661']

eng

2022 International Solid Freeform Fabrication Symposium

Open

Schwarz-P Lattices

Insight into Compressive Behaviour of Schwarz-P Lattices Fabricated by Material Extrusion

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3fd3b1b9-70b0-4888-af1c-2ace1428cd9b/download

null

Lattice structures are increasingly being chosen for lightweight applications due to their high strength- to-weight ratio and energy absorption capability. This work investigates the mechanical performance of the Schwarz-Primitive (SP) lattices with a range of unit-cell sizes and relative densities. The SP lattices were fabricated using material extrusion with ASA (industrial grade) and ABS material, then tested along different orientations to build direction. Digital Image Correlation (DIC) was utilised to measure the local strain and deformation mechanism. The preliminary results indicate that stiffness and strength were related to densities abiding the Ashby-Gibson model in well-controlled tight bands, which will help inform design decisions for future adoption. Further experiments will be conducted to extend the finding of this study, gain a better understanding of graded lattices and provide insights on the potential use of fibre reinforcement in lattices.

null

['Brown, Stephen W.', 'Przyjemski, Andrew G.', 'McPherson, Matthew B.', 'Steinberg, Jacob H.', 'Corbin, David', 'Reutzel, Edward W.']

2021-11-15T21:19:12Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90276', 'http://dx.doi.org/10.26153/tsw/17197']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['powder flow', 'deviations', 'directed energy distribution', 'additive manufacturing']

Insights into Powder Flow Characterization Methods for Directed Energy Distribution Additive Manufacturing Systems

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5aa7e094-24d5-40b8-bb3f-1f5a4172b14d/download

University of Texas at Austin

Powder-blown Directed Energy Distribution Additive Manufacturing systems often feed powdered metal into a melt pool generated by a laser. As the laser is moved, the melt pool solidifies, leaving behind a deposit. Such depositions may be built up into full components or used to add features on existing components. Distribution and uniformity of the powder flow is critical to achieve uniform and predictable depositions. For example, small deviations at the minute-level (cf. the resolution limit of the deposition) can propagate to gross deviations at the component-level. Meanwhile, large deviations in the powder flow can be yet unobservable to the naked eye, but produce catastrophic effects within small depositions. Such depositions are common to repair applications targeted at ARL Penn State, wherein relatively small deposits are created on larger, critical components. Novel and re-purposed OEM tools are compared to study these powder flow behaviors, providing new insights into process variability.

null

['Mijares, Jonathan', 'Mireles, Jorge', 'Gaytan, Sara M.', 'Espalin, David', 'Carter, William T.', 'Wicker, Ryan B.']

2021-10-12T22:10:41Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88751', 'http://dx.doi.org/10.26153/tsw/15685']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['multi-wavelength pyrometer', 'temperature monitoring', 'Electron Beam Melting', 'installation', 'thermal feedback']

Installation and Thermal Feedback from a Multi-wavelength Pyrometer in Electron Beam Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/84eb1a6d-50ac-4de5-99c3-2c06de321f10/download

University of Texas at Austin

The purpose of this paper is to outline and discuss the installation and use of a multi-wavelength pyrometer for process temperature monitoring in Electron Beam Melting (EBM). A multi-wavelength pyrometer was externally mounted atop an EBM system to observe and record surface temperatures during the fabrication process. The multi-wavelength pyrometer is a non-contact device capable of measuring the temperature of an object without the need of knowing the object’s emissivity. Temperature data from the EBM system thermocouple and the multi-wavelength pyrometer were compared, and it was determined that the pyrometer measurements were reasonable. During fabrication, the multi-wavelength pyrometer allowed the characterization of the EBM process that consisted of various steps during fabrication (e.g. heating of the build platform, powder deposition, and melting). Measurement of surface temperatures during fabrication can be useful for parameter development of novel materials, prediction of resulting microstructural architectures, and ultimately as feedback used in a closed-loop control system, allowing full spatial and temporal control of melting and microstructure.

null

['Shimek, M.', 'Lappo, K.', 'Wood, K.', 'Bourell, D.', 'Crawford, R.']

2019-11-21T18:15:13Z

2003

Mechanical Engineering

null

['https://hdl.handle.net/2152/78553', 'http://dx.doi.org/10.26153/tsw/5609']

eng

2003 International Solid Freeform Fabrication Symposium

Open

Prototypes

Instrumented Prototypes

Conference paper

https://repositories.lib.utexas.edu//bitstreams/05904cef-72fd-4ba4-b78e-4d2acf14227b/download

null

Full scale prototyping can be expensive and time consuming. Virtual prototypes reduce costs and time but often cannot be relied on for full scale production. Instrumented SFF prototypes update virtual prototypes, reducing cycle times and costs for full scale production. Both single and multi-layer access, two different methods for embedding sensors, are investigated at the University of Texas at Austin. Sensors are first embedded in a simulated SLS process to determine if embedding off the shelf sensors is feasible. Foil strain gages are then embedded into cantilever beams using multi-layer techniques. Both foil strain gages and bead type thermocouples are also embedded using single layer techniques. The results of the single layer tests will be used to construct a proof-of-concept prototype for single layer embedding.

null

['Pal, Deepankar', 'Patil, Nachiket', 'Nikoukar, Mohammad', 'Zeng, Kai', 'Haludeen Kutty, Khalid', 'Stucker, Brent E.']

2021-10-07T15:13:44Z

2012

Mechanical Engineering

null

['https://hdl.handle.net/2152/88474', 'http://dx.doi.org/10.26153/tsw/15410']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['in-situ process monitoring', 'finite element modeling', '3D dislocation density based', 'thermo-mechanical', 'post-process microscopy', 'mechanical testing', 'Additive Manufacturing', 'modeling software']

An Integrated Approach to Cyber-Enabled Additive Manufacturing using Physics based, Coupled Multi-scale Process Modeling

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c74cec12-34ee-42c9-b0aa-49207de18ece/download

University of Texas at Austin

The complexity of localized and dynamic boundary conditions in additive manufacturing processes makes it difficult to track in-situ thermo-mechanical changes at different length scales within a part using experimental equipment such as a FLIR1 system and other NDE2 techniques. Moreover, in-situ process monitoring is limited to providing information at an exposed surface of the build. As a result, an understanding of the bulk microstructure and behavior of a part still requires rigorous post-process microscopy and mechanical testing. In order to circumvent the limited feedback obtained from in-situ experiments and to better understand material response, a novel 3D dislocation density based thermo-mechanical finite element framework has been developed. This framework solves for the in-situ response 2 orders of magnitude faster than currently used state-of-the-art modeling software since it has been specifically designed for additive manufacturing platforms. Various aspects of this simulation tool have been and are being validated using research grants from NSF3, ONR4, AFRL5, NIST6 and NAMII7. This modeling activity has many potential commercial impacts, such as to predict the anisotropic performance of AM-produced components before they are built and as a method to enable in-situ closed-loop process control by monitoring the process and comparing it to predicted responses in real time (as the model will be used to predict results faster than an AM machine can build a part). This manuscript provides an overview of various software modules essential for creation of a robust and reliable AM software suite to address future needs for machine development, material (alloy) development and geometric optimization.

null

['Stucker, Brent', 'Qu, Xiuzhi']

2019-10-30T16:39:40Z

2002

Mechanical Engineering

null

['https://hdl.handle.net/2152/78189', 'http://dx.doi.org/10.26153/tsw/5278']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Finish Machining

An Integrated Approach to Finish Machining of RP Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c166bd5e-7a8d-4522-bf14-3693371714f7/download

null

An integrated approach to finish machining of RP parts and tools has been developed at the University of Rhode Island. Pre-processing operations, including surface offsets to add machining stock, and post-processing operations, including CNC tool-path generation, have been combined into one integrated set of software algorithms to make possible the effective finishing of near-net parts and tools from RP. An in-depth description of the uniquely developed STL vertex offset algorithm will be explored as well as an automatic method for adaptive raster milling, sharp edge contour machining and hole drilling from STL files. The time involved and surface finish benefits of the developed methodology will be compared to alternative approaches.

null

['Mahesh, M.', 'Loh, H.T.', 'Wong, Y.S.', 'Fuh, J.Y.H.']

2019-11-20T16:08:23Z

2003

Mechanical Engineering

null

['https://hdl.handle.net/2152/78466', 'http://dx.doi.org/10.26153/tsw/5551']

eng

2003 International Solid Freeform Fabrication Symposium

Open

RP Processes

Integrated Decision Support System for Selection of RP Processes

Conference paper

https://repositories.lib.utexas.edu//bitstreams/264d702f-86d4-46f1-99d2-2671023f9e7a/download

null

This paper describes an ‘Integrated Decision Support System for the Selection of RP Processes (IDSSSRP)’. The basic methodology proposed in the IDSSSRP is a Sigma approach towards benchmarking of the Rapid Prototyping (RP) processes. It characterizes a RP process by using benchmarking and the sigma approach to assess its capability compared to its potential. Although the six-sigma approach has basically been a management concept and the success of its implementation has been on process time reduction and quality improvement, this paper adopts the use of six-sigma tools and benchmarking in the characterization of RP processes. Apart from geometrical benchmarks, other benchmarks include mechanical benchmarks and process benchmarks. Benchmarking individual RP processes facilitates standardization and reduces variability in the prototypes produced by the processes. Following standardizations of geometrical, mechanical and process benchmarks, a saturated database can then become very useful in providing decision support to the end user on a particular process as well as a source of information for benchmarking new RP machines. A case study of the benchmarking process developed on the Direct Metal Laser Sintering-Selective Laser Sintering (DMLS-SLS) RP process is presented using the proposed approach. This paper also outlines the working and implementation of a web-based decision support system based on the IDSSSRP.

null

['Praniewicz, M.', 'Feldhausen, T.', 'Kersten, S.', 'Berez, J.', 'Jost, E.', 'Kurfess, T.', 'Saldana, C.']

2021-11-16T16:37:23Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90339', 'http://dx.doi.org/10.26153/tsw/17260']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['hardfacing', 'wear resistance', 'stellite-6', 'hybrid manufacturing']

Integrated Hardfacing of Stellite-6 Using Hybrid Manufacturing Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8b895029-654f-42fc-b413-36238c014307/download

University of Texas at Austin

Hybrid manufacturing systems provide a platform for integrated additive, subtractive and inspection methods on a single machine setup. The present work explores use of hybrid manufacturing for hardfacing of performance components for improving wear resistance. In this work, Stellite-6 was applied to a 410 stainless steel substrate using a hybrid manufacturing system incorporating multi-axis directed energy deposition and machining. Experimental testing was conducted to determine the effects of hybrid manufacturing parameters on internal porosity, surface porosity and microstructure in the cladded material, as well as on the roughness of the final machined surface. Correlation between porosity measurements made by x-ray tomography and surface inspection is presented and determination of ideal process parameters for hardfacing of components using hybrid manufacturing systems is briefly discussed. A deposition process is presented and implemented on a large industrial component. The component is inspected using dye-penetrant testing and metallographic techniques.

null

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

2021-09-30T18:56:36Z

9/23/10

Mechanical Engineering

null

['https://hdl.handle.net/2152/88279', 'http://dx.doi.org/10.26153/tsw/15220']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['worn-out components', 'laser cladding', 'non-contact freeform surface measurement', 'software system']

An Integrated Software System for Laser Cladding Repair of Worn-out Components

Conference paper

https://repositories.lib.utexas.edu//bitstreams/75b92b9c-d101-4916-bbef-c9a4a6cc4d50/download

University of Texas at Austin

Recovering worn-out tools/parts could have significant economic benefits. Traditionally, only some of these worn-out components can be repaired by conventional welding processes. Laser cladding is a material depositing method by which injected powder material is melted by a laser beam and re-solidified to form a dense coating with metallurgical bonding onto a substrate. This technology can be used in the component repair to restore undersized worn-out areas. Compared to conventional welding processes, laser cladding utilizes much less heat input with much better control, which drastically reduces or even eliminates distortion, and, therefore, enables the repair of complex components that cannot be repaired using conventional welding processes. Original CAD model does not represent the worn out component anymore and cannot be used directly for the component repair. Therefore, the first step in the laser cladding repair procedure is to extract the actual geometry of the components. Non-contact freeform surface measurement is widely used for this purpose. We developed a unique software system for laser cladding repair of worn-out components, which integrates the non-contact freeform surface measurement, the cladding path creation and the cladding program generation seamlessly. The surface contour is measured along with the predesigned scanning paths based on its original CAD model. The measured results are filtered to remove noise, and then compared with the CAD model. Finally, the cladding path planner creates the cladding program (G-code) based on the selected laser cladding parameters. Through this integrated software, the undersized worn-out components could be repaired effectively and easily by laser cladding process.

null

['Marsan, Anne L.', 'Allen, Seth', 'Kulkarni, Prashant', 'Dutta, Deba']

2018-12-07T16:21:59Z

1997

Mechanical Engineering

doi:10.15781/T20G3HJ5T

http://hdl.handle.net/2152/71446

eng

1997 International Solid Freeform Fabrication Symposium

Open

['CAD/CAM', 'LM processes']

An Integrated Software System for Process Planning for Layered Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/fcbafc73-5130-4351-8b2a-0f47ed02ad1a/download

null

An integrated process planning system for layered manufacturing (LM) reduces the time between design and part fabrication and improves the quality of the final part. Process planning for most LM processes includes part orientation, support structure generation, slicing, and path planning. In this paper we describe an integrated process planning system we are developing. Our software accommodates both novel and traditional design models as input, and supports a variety of LM processes. The modules described in this paper include Solid Builder Module, which generates a solid model from design data such as medical images, surface functions, or digital elevation models; Orientation Module, which determines the optimal build orientation of a part and automatically generates the support structures required; and Adaptive Slicing Module, which adaptively slices the part.

null

['Kruse, A.', 'Reiher, T.', 'Koch, R.']

2021-11-08T22:23:51Z

2017

Mechanical Engineering

null

['https://hdl.handle.net/2152/90055', 'http://dx.doi.org/10.26153/tsw/16976']

eng

2017 International Solid Freeform Fabrication Symposium

Open

['Designer', 'design engineering', 'part selection methodology', 'additive manufacturing', 'OptiAMix', 'BMBF']

Integrating AM into Existing Companies - Selection of Existing Parts for Increase of Acceptance

Conference paper

https://repositories.lib.utexas.edu//bitstreams/99390cc7-ca9f-4c4a-84a2-4b3aecd0adce/download

University of Texas at Austin

In many branches in the design engineer department, product designs are just variations of existing parts. To bring the additive manufacturing technology closer to the Designer, it is necessary to show them which of their existing, conventionally manufactured parts can be produced with this technology. A part selection methodology supports designers in the decision whether a part is suitable for additive manufacturing or not. Due to the potential of the technology, which was especially seen in the aerospace industries, many criteria of the methodology were initially adapted for this industry. Furthermore the methodology is based on a quantified weighting system, which comes to a certain subjectivity. For future use, a development towards a less subjective methodology should be accomplished. Through a more detailed adaption for individual industries and a simplification of the input mode, the objectivity of the criteria can be increased. Likewise, the input time can be reduced by simplifying the questioning. A more efficient part selection will be achieved by a better weighting system. In the BMBF project “OptiAMix” this methodology is supposed to be further developed for highly different branches. By a better weighting system, the part selection will be more efficient. Therefore, the willingness for the use of the improved selection and for the additive manufacturing technology will be increased.

null

['Altenhofen, C.', 'Loosmann, F.', 'Mueller-Roemer, J.S.', 'Grasser, T.', 'Luu, T.H.', 'Stork, A.']

2021-11-04T20:13:20Z

2017

Mechanical Engineering

null

['https://hdl.handle.net/2152/90020', 'http://dx.doi.org/10.26153/16941']

eng

2017 International Solid Freeform Fabrication Symposium

Open

['interactive design', 'mass customization', 'simulation', '3D-printed objects', 'cup holder']

Integrating Interactive Design and Simulation for Mass Customized 3D-Printed Objects - A Cup Holder Example

Conference paper

https://repositories.lib.utexas.edu//bitstreams/179d7749-52e2-4fc7-9c4d-269c14ba7142/download

University of Texas at Austin

We present an approach for integrating interactive design and simulation for customizing parameterized 3D models. Instead of manipulating the mesh directly, a simplified interface for casual users allows for adapting intuitive parameters, such as handle diameter or height of our example object – a cup holder. The transition between modeling and simulation is performed with a volumetric subdivision representation, allowing direct adaption of the simulation mesh without re-meshing. Our GPU-based FEM solver calculates deformation and stresses for the current parameter configuration within seconds with a pre-defined load case. If the physical constraints are met, our system allows the user to 3D print the object. Otherwise, it provides guidance which parameters to change to optimize stability while adding as little material as possible based on a finite differences optimization approach. The speed of our GPU-solver and the fluent transition between design and simulation renders the system interactive, requiring no pre-computation.

null

Asiabanpour, Bahram

2021-09-23T19:22:42Z

2008

Mechanical Engineering

null

['https://hdl.handle.net/2152/88018', 'http://dx.doi.org/10.26153/tsw/14960']

eng

2008 International Solid Freeform Fabrication Symposium

Open

['rapid prototyping', 'process development']

Integrating Rapid Prototyping into Product and Process Development

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0f6b5806-bc87-4014-bc77-45e388ffb7c2/download

null

Rapid prototyping concepts and skills are being taught to undergraduate manufacturing engineering students at Texas State University-San Marcos, not as an independent course, but as a part of the broad concept of product and process development. In such approach, students get a hands-on experience in a variety of rapid prototyping processes such as FDM, LOM, Zcorp 3DP, and 3D system’s InVision and they apply them in their industry-sponsored or research-based senior capstone design projects. In such approach students get a good understanding about the specifications, cost, and quality of the parts fabricated by each rapid prototyping machine. They also learn how to select the optimum process for each component of their product. In this paper, teaching and assessment methods for such learning experience are explained and a few samples of the previous projects are presented.

null

['Swank, M.L.', 'Strucker, B.E.', 'Medina, F.R.', 'Wicker, R.B.']

2021-09-28T18:57:28Z

9/15/09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88153', 'http://dx.doi.org/10.26153/tsw/15094']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['automated deposition system', 'support materials', 'Ultrasonic Consolidation', 'UC technology', 'FDM technology']

Integrating UC and FDM to Create a Support Materials Deposition System

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5b6d05ce-3a40-4409-9df1-456904b886a5/download

University of Texas at Austin

Currently there is no automated deposition system available for support materials in Ultrasonic Consolidation. Support materials are important to the UC technology because of the benefits that can be geometrically achieved. Without an integrated support materials system many geometries and features will be impossible to create. This paper describes the approach taken to integrate UC and FDM in order to automatically deposit materials as a support in a UC machine. This includes the process setup, design, and planning. Finally a build process integrating the two machines is shown to demonstrate that automated support material deposition in UC is possible.

null

['Hernandez, Ludwing A.', 'Strucker, Brent']

2021-09-28T19:00:16Z

9/18/09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88154', 'http://dx.doi.org/10.26153/tsw/15095']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['nScrypt Smart Pump', 'Solidica Formation', 'direct write nozzle', 'ultrasonic consolidation', 'rapid fabrication']

Integration & Process Planning for Combined Ultrasonic Consolidation

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8e76ece6-48ee-4131-943a-7665ec9f4a98/download

University of Texas at Austin

A research project is underway to integrate an nScrypt Smart PumpTM 100 direct write nozzle with a Solidica FormationTM ultrasonic consolidation machine to rapidly fabricate parts with novel multi-functional features. The process of integration of both machines has been addressed, and an appropriate process planning sequence to exploit the capabilities of the integrated technologies is developed. General processing guidelines are formulated, and form the basis for further fundamental research and for the production of proof of concept multi-functional parts to demonstrate the usefulness of this integration.

null

['Frank, Matthew C.', 'Croghan, Jakob', 'Larson, Samantha', 'Beguhn, Logan']

2021-11-16T16:31:59Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90337', 'http://dx.doi.org/10.26153/tsw/17258']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['integration challenges', 'metal AM', 'plastic AM', 'CNC milling machine', 'in-envelope hybrid manufacturing', 'additive manufacturing', 'subtractive manufacturing']

Integration Challenges with Additive/Subtractive In-Envelope Hybrid Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8c9d3f46-4ca9-4734-aef5-ff9a03fe5f13/download

University of Texas at Austin

There are significant practical challenges when combining additive and subtractive manufacturing systems. The integration of AM and machining processes can be done sequentially or in-envelope. A sequential example would be where an AM part is removed from the build plate and then fixtured into a milling machine; essentially post-processing a near-net shape part. Alternately, an AM system can be added to a milling machine or a milling process can be added to an AM system, which we would refer to as in-envelope. This paper presents some of the practical challenges of in-envelope hybrid manufacturing; both metal and plastic AM within a CNC milling machine. In this work, a method to accomplish iterative machining in the presence of extra material allowance and limited cutting tool lengths will be described. In addition, preliminary work on accommodating multi-materials within a hybrid system will be presented.

null

['Suh, Young S.', 'Wozny, Michael J.']

2018-11-08T14:48:27Z

1995

Mechanical Engineering

doi:10.15781/T24M91W5D

http://hdl.handle.net/2152/69878

eng

1995 International Solid Freeform Fabrication Symposium

Open

['SFF', 'CAD', 'prototypes']

Integration of a Solid Freeform Fabrication Process into a Feature-Based CAD System Environment

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8300e342-b899-4cb6-bf4c-62c5ccfdd75f/download

null

To cope with the increasing market competition, the concurrent engineering (CE) concept is being adopted by many companies to reduce the cost and the cycle time for manufacturing quality parts. To build a successful CE system where designers and manufacturing experts work simultaneously, the appropriate management of the product information flow among the users is essential. The product information include high-level data such as design intent, part functionality and manufacturing processes, which traditional CAD systems cannot support. To support such high-level information beyond geometric data in the CE system, feature-based CAD systems have been introduced to associate engineering meaning to the shapes of the CAD model components. In these systems, users can manipulate the CAD models in terms offeatures, and software algorithms can simulate the human behavior by manipulating the high-level feature entities, as oppose to the low-level geometric reasoning processes with blind searching algorithms. One of the primary application of the current SFF processes is to fabricate design prototypes for fast design verification: The process is identified to be a valuable tool in the CE environment because it can reduce the significant amount of design cycle time. Therefore" it is desirable that the SFF process software is fully integrated into the environment by taking a feature-based approach. As the process requires extensive geometric reasoning procedures that are time consuming and require complex algorithms, the feature-based approach is appropriate, and more intelligent processing is possible. Also, an algorithm can be easily customized

null

['Rodriguez, Emmanuel', 'Medina, Francisco', 'Espalin, David', 'Terrazas, Cesar', 'Muse, Dan', 'Henry, Chad', 'MacDonald, Eric', 'Wicker, Ryan B.']

2021-10-06T22:45:26Z

8/15/12

Mechanical Engineering

null

['https://hdl.handle.net/2152/88465', 'http://dx.doi.org/10.26153/tsw/15402']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['Electron Beam Melting', 'thermal imaging', 'infrared camera', 'fabrication control']

Integration of a Thermal Imaging Feedback Control System in Electron Beam Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a6ca23d9-0fe5-418e-a693-675d7cd5efeb/download

University of Texas at Austin

A thermal imaging system using an infrared (IR) camera was incorporated in the fabrication process of an Arcam A2 Electron Beam Melting system to provide layer-by-layer feedback and ensure quality and defect free products. Using the IR camera, build chamber surface temperature profiles were imaged and analyzed, providing information used to modify build settings for the next build layer. Individual part temperatures were also monitored and modified to achieve a more uniform bed temperature. The thermal imaging information can also be used as a quality control tool to detect imperfections during the build. Results from the integration of the camera in the system as well as use of the thermal images in process monitoring and control is described.

null

['Robinson, Christopher J.', 'Stucker, Brent', 'Lopes, Amit J.', 'Wicker, Ryan', 'Palmer, Jeremy A.']

2020-02-27T19:44:19Z

9/14/06

Mechanical Engineering

null

['https://hdl.handle.net/2152/80096', 'http://dx.doi.org/10.26153/tsw/7117']

eng

2006 International Solid Freeform Fabrication Symposium

Open

Ultrasonic Consolidation

Integration of Direct-Write (DW) and Ultrasonic Consolidation (UC) Technologies to Create Advanced Structures with Embedded Electrical Circuitry

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9d682a17-2c52-4f43-b0a1-6c4e458546fa/download

null

In many instances conductive traces are needed in small, compact and enclosed areas. However, with traditional manufacturing techniques, embedded electrical traces or antenna arrays have not been a possibility. By integrating Direct Write and Ultrasonic Consolidation technologies, electronic circuitry, antennas and other devices can be manufactured directly into a solid metal structure and subsequently completely enclosed. This can achieve a significant reduction in mass and volume of a complex electronic system without compromising performance.

null

['Pintant, T', 'Sindel, M.', 'Greul, M.', 'Burblies, A.', 'Wiklening, C.']

2018-10-03T15:21:21Z

1994

Mechanical Engineering

doi:10.15781/T2DZ03M36

http://hdl.handle.net/2152/68643

eng

1994 International Solid Freeform Fabrication Symposium

Open

['Investment casting', 'Laser sintering', 'Rapid prototyping']

Integration of Numerical Modeling and Laser Sintering with Investment Casting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a799964f-7b43-406a-bb20-14b5f64b811f/download

null

Industry has a great demand for metallic prototypes to speed up product development. At present there are several RP-technologies for direct fabrication of metal components in development. Today secondary processing of polymer or wax models, like investment casting or sand casting, is a very common way for the production of metallic prototypes. There are, however, several problems in investment casting resulting from laser sintered models made of wax or polycarbonate. Recently a polymer mixture consisting of nylon material and a second polymer has been tested with the laser sinter process in a newly developed sinter machine (EOSINT 350 - 60). Shells for investment casting could be prepared easily with the models in a conventional assembly-line. Several castings of laser sintered models in Al were successfully realized. In future, integration of modeling based on FEM calculations with RP for castings will become more important. Calculations will support the designer to optimize the structure of components and their processing. A viable method will be presented where a new FEM based calculation method to optimize the structure design of a model is integrated with RP. Optimizing castings with FEM will be supported by integration with RP.

null

['Hague, R.', 'Campbell, I.', 'Dickens, P.', 'Reeves, P.']

2019-10-18T17:13:07Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76267', 'http://dx.doi.org/10.26153/tsw/3356']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Fabrication

Integration of Solid Freeform Fabrication in Design

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0e8508cb-a677-4b59-9891-f134d760c5ee/download

null

During the last few decades, designers have been educated to develop designs with restricted geometry so that parts can be made easily. The revolutionary aspect of Rapid Manufacturing will be that geometry will no longer be a limiting factor. The introduction of Rapid Manufacturing will have a number of effects on Design. It will be possible to have re-entrant shapes without complicating manufacturing, no draft angles, variable wall thickness, no split lines and fewer parts leading to easier assembly and lower stock. The individual designer’s method of working will change with the introduction of Rapid Manufacturing and also there will be changes to the overall design process. Examples will be the elimination of prototype and pre-production stages, as end part manufacture will occur as soon as the CAD is finished. This will affect project management practices and sign-off procedures.

null

['Cheng, Lin', 'Zhang, Pu', 'Biyikli, Emre', 'Bai, Jiaxi', 'Pilz, Steve', 'To, Albert C.']

2021-10-21T18:43:57Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89424

eng

2015 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'topology optimization', 'cellular structure', 'reconstruction']

Integration of Topology Optimization with Efficient Design of Additive Manufactured Cellular Structures

Conference paper

https://repositories.lib.utexas.edu//bitstreams/197ee039-06b0-47fc-9515-58b753d6f387/download

University of Texas at Austin

Cellular structures are promising candidates for additive manufacturing to design lightweight and complex parts to reduce material cost and enhance sustainability. In the paper, we focus on the integration of the topology optimization with the additive manufactured cellular structures. In order to take advantage of these two technologies for lightweight manufacturing, a totally new design and CAD method is developed to build up the bridge between the optimal density distribution and the cellular structure. First, a systematic theoretical and experimental framework is provided to obtain the mechanical properties of cellular structures with variable density profile. Second, a revised topology optimization algorithm is introduced to optimize arbitrary 3D models with given boundary conditions. In this process, the minimum compliance problem and allowable stress problem are considered to get the relative density distribution. Third, CAD methods are developed to obtain the function between the local relative density and the variable density of cellular structure. With the aid of the function, one can convert the density distribution to the cellular vertex radius distribution and build variable density cellular structures in the given parts. Finally, a real part named pillow bracket is designed by this process to illustrate the efficiency and reliability of the new method.

null

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

2021-10-28T14:43:38Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89654

eng

2016 International Solid Freeform Fabrication Symposium

Open

['computer aided design', 'CAD', 'functional gradient materials', 'source-based', 'voxel-based']

Integration of Voxel Based and Source Based Representation for Computer Aided Design of Functional Gradient Materials

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0251655a-067c-4e37-abc9-8993bab7ebad/download

University of Texas at Austin

Functionally Gradient Materials (FGMs) feature smooth transition from one material to another within a single object. FGMs modeling is considered to be one of the new challenges in Computer Aided Design area. To overcome this challenge, this paper presents the integration of a source-based and voxel-based approach to model FGMs. The input of STL format can be meshed and voxelized. The material composition and material varying information in each voxel can be generated from control sources. In addition, surface source is used to define default material information, and several filtering methods, including Gaussian filter, Average filter, are applied to blend FGMs for each voxel.

null

['Liou, Frank W.', 'Leu, Ming C.', 'Landers, Robert G.']

2021-10-05T15:39:13Z

8/16/12

Mechanical Engineering

null

['https://hdl.handle.net/2152/88393', 'http://dx.doi.org/10.26153/tsw/15332']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['Additive Manufacturing', 'education program', 'society', 'societal integration', 'Missouri University of Science and Technology']

Interactions of an Additive Manufacturing Program with Society

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e6e42722-51f8-46a6-9e25-b287511bd6e8/download

University of Texas at Austin

Additive Manufacturing (AM) has shown considerable promise for the future but also proposes some challenges. Many AM barriers tend to be non-technical and instead are humancentric issues such as lack of education of practitioners in AM capabilities, cultural differences, vested interests, and potentially lack of imagination. It is highly desirable for all research and educational institutions to help address these issues. This paper summarizes the additive manufacturing research and education program at the Missouri University of Science and Technology (Missouri S&T) and its interactions with various constituents, including K-12 students, undergraduate and graduate students, distance students, and industry.

null

['Choi, S. H.', 'Samavedam, S.']

2019-03-04T17:29:52Z

1999

Mechanical Engineering

null

['https://hdl.handle.net/2152/73528', 'http://dx.doi.org/10.26153/tsw/678']

eng

1999 International Solid Freeform Fabrication Symposium

Open

['evalutaion', 'concept']

An Interactive Virtual System for Simulation and Optimization of Rapid Prototyping

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f4a672eb-bf17-4289-82bc-6487abb96154/download

null

The paper describes the development of a computer system for simulation and optimization of rapid prototyping (RP) processes. The system provides a test-bed for virtual prototyping by integrating product design and RP with simulation and realistic visualization techniques. It enhances the dimensional accuracy and reduces the build-time of product prototypes. The virtually fabricated parts may be exported in VRML format over the Internet for effective communication between the manufacturer and the customer. The designer may use the system to design-build-break as many parts as required at a relatively low cost andin a short period of time. Therefore, virtual simulation of RP processes facilitates tuning of the control parameters according to the requirements, and hence reduces the number of physical prototypes needed to produce a part.

null

['Jacobsen, A.J.', 'Kolodziejska, J.A.', 'Doty, R.', 'Fink, K.D.', 'Zhou, C.', 'Roper, C.S.', 'Carter, W.B.']

2021-10-01T00:25:55Z

2010

Mechanical Engineering

null

['https://hdl.handle.net/2152/88308', 'http://dx.doi.org/10.26153/tsw/15249']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['open-cellular materials', 'micro-scale truss', 'lattice features', 'interconnected self-propagating photopolymer waveguides', 'three-dimensional open-cellular polymer', 'bio-scaffolds']

Interconnected Self-Propagating Photopolymer Waveguides: An Alternative to Stereolithography for Rapid Formation of Lattice-Based Open-Cellular Materials

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f494cc54-5395-4939-be7d-fab110691458/download

null

Recently, a new technique has been developed to create unique open-cellular materials with micro-scale truss, or lattice features ranging from tens to hundreds of microns. These materials are formed from a three-dimensional, interconnected array of self-propagating photopolymer waveguides. By utilizing this self-propagating effect, three-dimensional open-cellular polymer materials can be formed in seconds. In addition, intrinsic to the process is the ability to control specific micro-lattice parameters which ultimately affect the bulk material properties. Unlike stereolithography, this new fabrication technique is rapid (~ minutes to form an entire part) and relies on a single two-dimensional exposure surface to form three-dimensional structures (thickness > 25 mm possible). This combination of speed and planar scalability opens the possibility for large-scale mass manufacturing. The utility of these new materials range from lightweight energy absorbing structures to thermal management materials to bio-scaffolds.

null

['Janaki Ram, G. D.', 'Yang, Y.', 'Nylander, C.', 'Aydelotte, B.', 'Stucker, B. E.', 'Adams, B. L.']

2020-03-09T15:12:35Z

9/5/07

Mechanical Engineering

null

['https://hdl.handle.net/2152/80193', 'http://dx.doi.org/10.26153/tsw/7212']

eng

2007 International Solid Freeform Fabrication Symposium

Open

Additive manufacturing

Interface Microstructures and Bond Formation in Ultrasonic Consolidation

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b13365d9-24a0-42c0-93f4-6193081e6765/download

null

The quality of ultrasonically consolidated parts critically depends on the bond quality between individual metal foils. This necessitates a detailed understanding of interface microstructures and ultrasonic bonding mechanism. There is a lack of information on interface microstructures in ultrasonically consolidated parts as well as a lack of consensus on the mechanism of metal ultrasonic welding, especially on matters such as plastic deformation and recrystallization. In the current work, interface microstructures of an ultrasonically consolidated multi-material Al 3003-Ni 201 sample were analyzed in detail using optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, and orientation imaging microscopy. Based on the results of microstructural studies, the mechanism of metal ultrasonic welding has been discussed. The reasons for formation of defects/unbonded regions in ultrasonically consolidated parts have also been identified and discussed

null

['Vail, N.K.', 'Wilke, W.', 'Bieder, H.', 'Jiinemann, G.']

2018-11-15T20:58:46Z

1996

Mechanical Engineering

doi:10.15781/T23N21073

http://hdl.handle.net/2152/70280

eng

1996 International Solid Freeform Fabrication Symposium

Open

['CAD', 'REEN', 'reverse engineering']

Interfacing Reverse Engineering Data to Rapid Prototyping

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9fc4df49-dc47-4770-974d-f7b817c0cb54/download

null

Rapid prototyping has become an increasing part of product development process chains resulting in reduced time to market and reduced development costs. As manufacturers strive to further reduce development cycles to maintain market competitiveness, the use ofreverse engineering technologies have started to play key roles in the product development cycles. Integration of these technologies into existing development cycles provides tools to maintain design integrity during development stages as well as between successive product lines. One aspect ofreverse engineering is the intert'acing of data obtained from these technologies to manufacturing processes such as rapid prototyping. This paper discusses work at Daimler-Benz to develop a set ofinterlacing tools as part of a larger reverse engineering process loop. These tools include facilities to generate contiguous surt'ace meshes from a collection ofmeasured views as well as automatic feature detection and hole closure.

null

['Pedersen-Bjergaard, Jonathan Taulo', 'Christensen, Mathias Michael', 'Brander, Marco', 'Seta, Berin', 'Pedersen, David Bue', 'Spangenberg, Jon']

2023-01-20T16:43:23Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117264', 'http://dx.doi.org/10.26153/tsw/44145']

eng

2022 International Solid Freeform Fabrication Symposium

Open

thermoset

Interlayer Mechanical Properties of Thermoset Components Produced by Material Extrusion Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b264a967-759d-4b04-8793-0d9edf6338fc/download

null

Material extrusion additive manufacturing (MEX-AM) with thermoset media is of interest as its unique material properties are advantageous for many applications. However, thermoset MEX-AM’s resultant interlayer mechanical properties have not yet been fully ascertained. In this study, a robot arm and extrusion system are used to 3D print a two-component polyurethane with depositions of varying holding intervals between layers, to quantify the effect on interlayer- stiffness and –strength. The material is extruded through a 7 mm nozzle to fabricate 42 mm high walls with a width equal to a single strand. The bulk- and interlayer mechanical properties are measured through tensile testing of dogbone samples. The results indicate that the interlayer mechanical properties do not reduce as compared to the bulk behavior.

null

['Wood, Nathaniel', 'Mendoza, Heimdall', 'Boulware, Paul', 'Hoelzle, David J.']

2021-11-18T18:13:03Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90452', 'http://dx.doi.org/10.26153/tsw/17373']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['internal temperature distributions', 'powder bed fusion', 'stainless steel 316']

Interrogation of Mid-Build Internal Temperature Distributions Within Parts Being Manufactured via the Powder Bed Fusion Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4b19bdf2-c3ee-479e-8cc9-b364052efba4/download

University of Texas at Austin

This work reports on the measurement of the internal temperature distributions of parts being manufactured via the Powder Bed Fusion (PBF) process. Eight test coupons were machined from a piece of wrought 304 stainless steel (SS). Thermocouples were inserted into the test coupon interiors to sample internal thermal history. The coupons were then placed into the open architecture laser PBF machine housed at EWI and covered to their uppermost surfaces with 316 SS powder. Three tests were executed: First, the laser rastered over the coupons without inducing melting. Second, the laser rastered over the coupons while melting the exposed faces. Lastly, five layers of 316 SS were built atop the coupons. The main result is a comprehensive data set of a multitude of measured physical inputs and outputs under typical build conditions: embedded thermocouple temperatures, laser centroid, laser power, and infrared imagery of the exposed coupon faces.

null

['Marchelli, Grant', 'Storti, Duane', 'Ganter, Mark', 'Prabhakar, Renuka']

2021-09-30T13:07:47Z

9/23/10

Mechanical Engineering

null

['https://hdl.handle.net/2152/88227', 'http://dx.doi.org/10.26153/tsw/15168']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['virgin glass', 'recycled glass', '3D printing', '3DP glass systems']

An Introduction to 3D Glass Printing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c8f59e37-727f-4534-8c81-0dd629a24ce2/download

University of Texas at Austin

This paper provides an overview of the process behind successfully adapting new materials, namely virgin glass and recycled glass, to 3D printing. The transition from 3DP ceramic systems to glass systems will be examined in detail, including, the necessary modifications to binder systems and printing parameters. We present preliminary engineering data on shrinkage and density as functions of peak firing temperature. In addition, we will provide a brief introduction to the complexities faced in realizing an adequate and repeatable firing method for printed glass.

null

['Lao, S.', 'Koo, J. H.', 'Morgan, A.', 'Yong, W.', 'Tower, C.', 'Jor, H.', 'Moon, T.', 'Wissler, G.', 'Pilato, L.', 'Luo, Z. P.']

2020-03-09T15:27:45Z

2007

Mechanical Engineering

null

['https://hdl.handle.net/2152/80198', 'http://dx.doi.org/10.26153/tsw/7217']

eng

2007 International Solid Freeform Fabrication Symposium

Open

carbon nanofibers

Intumescent Flame Retardant Polyamide 11 Nanocomposites

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b06a3771-8b5f-4c64-a722-ced28b48c5b2/download

null

Current polyamide 11 and 12 are lacking in fire retardancy and high strength/high heat resistance characteristics for a plethora of fabricated parts that are desired and required for performance driven applications. The introduction of selected nanoparticles such as surface modified montmorillonite (MMT) clay or carbon nanofibers (CNFs), combined with a conventional intumescent flame retardant (FR) additive into the polyamide 11/polyamide 12 (PA11/PA12) by melt processing conditions has resulted in the preparation of a family of intumescent polyamide nanocomposites. These intumescent polyamide 11 and 12 nanocomposites exhibit enhanced polymer performance characteristics, i.e., fire retardancy, high strength and high heat resistance and are expected to expand the market opportunities for polyamide 11 and polyamide 12 polymer manufacturers. 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 combining it with a conventional intumescent FR additive via twin screw extrusion. Arkema RILSAN® polyamide 11 molding polymer pellets were examined with two types of nanoparticles: chemically modified montmorillonite (MMT) organoclays, and carbon nanofibers (CNFs); and Clairant’s Exolit® OP 1230 intumescent FR additive were used to create a family of FR intumescent polyamide 11 nanocomposites. Transmission electron microscopy (TEM) was used to determine the degree of nanoparticles dispersion. Injection molded specimens were fabricated for physical, thermal, and flammability measurements. Thermal stability of these intumescent polyamide 11 nanocomposites was examined by TGA. Flammability properties were obtained using the Cone Calorimeter at an external heat flux of 35 kW/m 2 and UL 94 Test Method. Heat deflection temperatures (HDT) were also measured. TEM micrographs, physical, thermal, and flammability properties are presented. FR intumescent polyamide 11 nanocomposites properties are compared with polyamide 11 baseline polymer. Based on flammability and mechanical material performance, selective polymers including polyamide 11 nanocomposites and control polyamide 11 will be cryogenically ground into fine powders for SLS RM processing. SLS specimens will be fabricated for thermal, flammability, and mechanical properties characterization.

null

['Brown, Don R.', 'Subramanyan, Venkatesh', 'Drake, Samuel']

2018-04-12T18:03:44Z

1991

Mechanical Engineering

doi:10.15781/T2TX35P9B

http://hdl.handle.net/2152/64276

eng

1991 International Solid Freeform Fabrication Symposium

Open

['Mechanical Engineering and Computer Science Departments', 'stereolithography', 'inverse geometry']

Inverse Geometry for Stereolithographic Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1c61efa9-450c-4a9d-8d30-584d539287f9/download

null

As parts produced by stereolithography form and cure, they warp and shrink to produce Pitrts that are not quite the san~ ~ as those originally specified. This research attempts to solve the inverse geomptry problem, that is, what shape should be specified initially so that the she pe produced is the desired one. Assuming that 'the process is repeatable, we ~neasure the difference between the ideal and actua). part dimensions. A finite-element based model is built which mirrors the distortion from the ideal geometry. A "pre-deformed" geometry is then built so that it deforms to the ideal geometry under the conditions imposed on the finite element model. This pre-warped geometry is the geometry we seek.

null

['Khan, Md Faysal', 'Nezhadfar, P.D.', 'Gradl, Paul R.', 'Godfrey, Donald', 'Diemann, Jacky', 'Shao, Shuai', 'Shamsaei, Nima']

2023-01-20T17:02:07Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117267', 'http://dx.doi.org/10.26153/tsw/44148']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Laser powder bed fusion (L-PBF)', 'AlF357', 'Height dependency', 'Microstructure', 'Porosity', 'Tensile properties']

Investigate the height dependency of the micro-/defect-structure and mechanical properties of additively manufactured AlF357 aluminum alloy

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0068f1c8-8acc-4193-838f-edfe928b205b/download

null

When the laser powder bed fusion (L-PBF) additive manufacturing method is employed to build parts with increased heights, there is a possibility that defects are increased in part. This study investigates the effect of build height on the micro-/defect-structure and, consequently, the mechanical properties of L-PBF AlF357, an Al-Si-Mg alloy family. Tall vertical cylinders of 316 mm with 15 mm diameter were fabricated and cut into specimens at different heights. Although not much difference is observed in the microstructure (grain size and morphology), the defects' size and population slightly vary with height. Nonetheless, the tensile properties of the L-PBF AlF357 are found to be independent of height. This is ascribed to the approximately identical microstructure and marginal difference in the defect's size and distribution along the heights.

null

['Taylor, Samantha', 'Jared, Bradley', 'Koepke, Josh', 'Forrest, Eric', 'Beaman, Joseph']

2021-11-18T18:56:20Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90467', 'http://dx.doi.org/10.26153/tsw/17388']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['surface roughness', 'arithmetic roughness', 'roughness parameters', 'applicability', 'metallic additive manufacturing']

Investigating Applicability of Surface Roughness Parameters in Describing the Metallic AM Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/78aca229-a5fa-4981-af43-106163d40fb2/download

University of Texas at Austin

Additive manufacturing (AM) is known for its large variance in mechanical properties. This is not only true for properties like strength, but also surface roughness. Build settings, which affect surface roughness, are often chosen to optimize strength or ductility. As part requirements change, build settings change, thereby changing resultant surface roughness. When describing surfaces, arithmetic roughness (Ra) is the most common parameter. However, it may not provide an adequate representation of surface topography for AM parts. Traditional surface roughness parameters for defining surface topography were well-established before the advent of AM, and a need has arisen to investigate applicability of these parameters to the unusual surfaces created through various AM technologies. This study demonstrates that Ra is not a suitable parameter in correlating surface topography to AM build parameters. Other existing parameters and combination of parameters will be investigated for their suitability in describing the AM process.

null

['Thompson, Matthew J.', 'Whalley, David C.', 'Hopkinson, Neil']

2020-03-10T17:22:57Z

9/10/08

Mechanical Engineering

null

['https://hdl.handle.net/2152/80233', 'http://dx.doi.org/10.26153/tsw/7252']

eng

2008 International Solid Freeform Fabrication Symposium

Open

Selective Laser Sintering

Investigating Dielectric Properties of Sintered Polymers for Rapid Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6e2737d3-c16f-45f7-8a95-115553809857/download

null

Selective Laser Sintering (SLS) of polymers is the leading technology in the growing field of Rapid Manufacturing. High Speed Sintering (HSS) is a process that offers the potential to reduce costs and processing times and thus open significant new markets for Rapid Manufactured parts. Much academic research has been performed with respect to mechanical properties of Rapid Manufactured parts, however the area of electrical properties has received little attention to date. Electrical properties are obviously important in applications that will involve embedding of circuits with Rapid Manufactured 3D objects. However electrical properties are also important for a wide variety of electrical products where Rapid Manufactured parts can be used as housings etc. This paper focuses on the dielectric properties of parts made by SLS and HSS and compares properties with those for conventionally processed polymers. Dielectric strength results show that SLS parts are comparable with injection moulded parts, while HSS parts are inferior to SLS parts. Dielectric constant and dissipation factor results show that HSS parts are comparable with injection moulded parts, whilst SLS parts have superior properties. The presence of porosity (SLS and HSS) and the presence of carbon (HSS) are suggested as reasons behind the variation in dielectric properties when compared with injection moulded parts.

null

['Tanney, Daniel', 'Meisel, Nicholas A.', 'Moore, Jacob']

2021-11-02T18:20:30Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89857

eng

2017 International Solid Freeform Fabrication Symposium

Open

['recycled PLA', 'PLA', 'material degradation', 'lifecycle', 'material extrusion', 'additive manufacturing']

Investigating Material Degradation Through the Recycling of PLA in Additively Manufactured Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/06a6f180-cdc7-44be-a108-f855e1cda20a/download

University of Texas at Austin

The field of additive manufacturing (AM) has been expanding rapidly with the decreasing cost of desktop-scale material extrusion AM systems. As the cost of AM systems decreases, more users are investing in the technology, including universities, which have turned to AM as an option for providing wide-scale access to prototyping technology. However, this type of wide-access printing generates significant waste due to cast-off support material as well as failed prints from inexperienced users. This paper investigates the feasibility of recycling this cast-off material through the relationship between the mechanical properties of recycled PLA and the number of lifecycles it has experienced on a desktop material extrusion machine. A three-stage pelletizing, extrusion, and printing process is used to investigate recycling of PLA material from cast-off build material. Additionally, the research investigates how adding virgin pellets to pellets of the recycled material in various ratios can affect tensile properties.

null

['Haigh, B.', 'Lancaster, R.J.', 'Johnston, R.', 'White, M.', 'Minshull, J.']

2021-11-18T00:36:21Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90373', 'http://dx.doi.org/10.26153/tsw/17294']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['Inconel 718', 'laser powder bed fusion', 'small punch', 'microstructure', 'porosity']

Investigating the Build Consistency of a Laser Powder Bed Fused Nickel-Based Superalloy, Using the Small Punch Technique

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d822dee5-54d2-4d90-b6be-bebbd152c7b9/download

University of Texas at Austin

Inconel 718 (IN718) is a nickel-based superalloy that possesses impressive corrosion resistance and high strength properties at elevated temperatures, making it an ideal choice for aerospace applications. However, with the continuous evolution of the jet engine, there is a strong desire to fabricate more intricate components with less stress-raising features to enable higher engine efficiencies to be achieved. To overcome this issue, aerospace engineers are looking at Additive Manufacturing (AM) as a potential solution. A limitation of AM is the transient nature of the microstructure, and it is difficult to produce representative laboratory scale mechanical test specimens that closely replicate the microstructure of the finished component. Therefore, it can be beneficial to utilise small-scale test methods, such as the Small Punch (SP) test, which can obtain mechanical property information from miniaturised specimens extracted directly from the finished part. In this paper, the small punch test technique has been adopted to characterise and evaluate the mechanical response of laser powder bed fused (LPBF) Inconel 718. Results showed a high consistency across builds and certain orientations exhibited superior properties.

null

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

2023-01-25T14:23:45Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117289', 'http://dx.doi.org/10.26153/tsw/44170']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Additive manufacturing', 'crystal plasticity simulation', 'IN718', 'Defects']

Investigating the effect of defects on the crack initiation of additively manufactured IN718 using crystal plasticity simulations

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e82572f3-3023-4384-b303-933e0d76108d/download

null

This study aims to analyze the effect of defects location on the fatigue behavior of additively manufactured IN718. A competing mechanism exists between persistent slip bands (PSBs) and volumetric defects on the initiation of fatigue cracks in AM IN718 under cyclic loading. Crystal plasticity simulations were performed to reveal the relative importance in crack initiation due to defects and PSBs. Cyclic loading was applied on a defect laden polycrystalline aggregate and the defect locations were systematically varied. The crack nucleation cycles and locations were captured using a strain contrast-based crack initiation criterion. The findings suggest that the presence of large defects affects the cyclic strain localization and crack initiation behavior of the AM IN718 material.

null

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

2024-03-26T17:06:36Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124377', 'https://doi.org/10.26153/tsw/50985']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['generalized Newtonian fluid', 'large area additive manufacturing', 'deposition beads']

Investigating the Effect of Generalized Newtonian Fluid on the Micro-Void Development within Large Scale Polymer Composite Deposition Beads

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e05a5797-34a7-47c4-8b88-052705916053/download

University of Texas at Austin

The formation and development of micro-voids within the bead microstructure of a polymer composite during the extrusion/deposition additive manufacturing process continues to be of interest given the adverse effect these features have on part quality. A computational method is employed here to investigate potential volatile-induced micro-void nucleation mechanism which simulates the evolution of a single rigid ellipsoidal fiber in purely viscous polymer extrusion/deposition flow through a Large Area Additive Manufacturing (LAAM) nozzle. Our previous studies on potential micro-void nucleation mechanisms have assumed a Newtonian fluid property definition for the polymer melt flow, the current study assesses the effect of assuming a generalized Newtonian fluid (GNF) model on the fiber’s response. Preliminary findings based on Jeffery’s flow assumption reveal the fiber’s orientation kinetics are unaffected by the shearthinning fluid behavior, however there is a reduction in the pressure distribution on the fiber’s surface as the power law index is decreased which is expected to reduce the likelihood for microvoid nucleation.

null

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

2021-12-06T22:38:15Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90701', 'http://dx.doi.org/10.26153/tsw/17620']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['laser powder bed fusion', 'Inconel 718', 'microstructure', 'Vickers hardness', 'homogenity']

Investigating the Effect of Heat Transfer on the Homogenity in Microstructure and Properties of Inconel 718 Alloy Fabricated by Laser Powder Bed Fusion Technique

Conference paper

https://repositories.lib.utexas.edu//bitstreams/fb6ee87f-5cdf-42db-90f4-cb3bd90dfe88/download

University of Texas at Austin

Laser Powder Bed Fusion (LPBF) of metallic components is associated with microstructure and inhomogeneity of properties in the fabricated components. In a recent work by the authors, a novel technique of considering a border surrounding the main part during the LPBF fabrication is proposed to address the issue of inconsistency in microstructure across the cross section of LPBF-fabricated parts. This study, on the other hand, aims to investigate the effect of such border on the microstructure homogeneity along the build direction of LPBF-fabricated parts. For this purpose, a cubic sample surrounded by a cubic border was fabricated to control the rate of heat transfer and then improve the microstructure across the cross section. Also, a sample with identical dimensions and the same process parameters was printed without border as a reference to be compared. To investigate the variation of the properties along the build direction, microstructure and hardness results were compared between areas near and away the substrate for both samples. For the area away from the substrate, in both samples, a deeper pool, less surface porosity, and higher Vickers hardness was observed compared to the area near the substrate. It was found out that, regardless of the focused area, the sample fabricated with border possesses deeper pools, higher level of density as well as higher hardness value. However, in term of homogeneity along the build direction, no significant improvement was observed for the sample fabricated with the cubic border.

null

['Bracken, Jennifer', 'Bentley, Zachary', 'Meyer, James', 'Miller, Erik', 'Jablokow, Kathryn W.', 'Simpson, Timothy W.', 'Meisel, Nicholas A.']

2021-11-16T15:52:30Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90321', 'http://dx.doi.org/10.26153/tsw/17242']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['AM workshop', 'idea generation', 'problem solving', 'additive manufacturing']

Investigating the Gap Between Research and Practice in Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2b920d3d-8657-4e2c-9098-f4f2bc1102af/download

University of Texas at Austin

Additive manufacturing (AM) provides opportunities to design objects differently than traditional manufacturing methods allow, but only if designers understand the possibilities AM presents. In this study, we examined whether an AM workshop combined with an idea generation session could inspire engineering professionals to use AM solutions to solve current technical problems they face. All subjects were employees at an organization that will be referred to as Company X, a multinational commercial organization based in North America. During the study, we collected ideas for 24 projects generated before and after a training workshop focused on design for AM. In the workshop, we provided three hours of instruction about design for two metal-based AM processes. The participants’ ideas were assessed using four specific metrics: (1) cost, (2) time, (3) completeness of solution, and (4) quality, which was a function of feasibility, usefulness, and novelty. Using these data, we explored whether the workshop was effective in inspiring the participants to use AM methods and techniques from AM research in their concept generation and whether participants’ AM solutions showed improvement in cost, implementation time, and quality over non-AM designs generated before the workshop.

null

['Kaweesa, Dorcas V.', 'Spillane, Daniel R.', 'Meisel, Nicholas A.']

2021-11-02T18:54:10Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89865

eng

2017 International Solid Freeform Fabrication Symposium

Open

['functionally graded material', 'fatigue life', 'multi-material specimens', 'material jetted specimens', '3D printing']

Investigating the Impact of Functionally Graded Materials on Fatigue Life of Material Jetted Specimens

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b22495c8-0fce-4e06-80a5-2c6f841852d0/download

University of Texas at Austin

The capability of Additive Manufacturing (AM) to manufacture multi-materials allows the fabrication of complex and multifunctional parts with varying mechanical properties. Multi-material AM involves the fabrication of 3D printed objects with multiple heterogeneous material compositions. The material jetting AM process specifically has the capability to manufacture multi-material structures with both rigid and flexible material properties. Existing research has investigated the fatigue properties of 3D printed multi-material specimens and shows that there is a weakness at the multi-material interface. This paper seeks to investigate the effects of gradual material transitions on the fatigue life of 3D printed multi-material specimens, given a constant volume of flexible material. In order to examine the fatigue life at the multi-material interface, discrete digital-material gradient steps are compared against the true functional gradients created through voxel-level design. Results demonstrate the negative effects of material gradient transitions on fatigue life as well as the qualitative material properties of true versus discrete gradients.

null

['Salajeghe, Roozbeh', 'Kruse, Carl Sander', 'Meile, Daniel Helmuth', 'Marla, Deepak', 'Spangenberg, Jon']

2023-01-26T15:55:38Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117322', 'http://dx.doi.org/10.26153/tsw/44203']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Volumetric additive manufacturing', 'Volume of Fluid', 'Sedimentation', 'Boussinesq approximation', 'ultra-violet (UV) Curing', 'Photopolymerization']

Investigating the influence of thermal and mechanical properties of resin on the sedimentation rate of the printed geometry in the volumetric additive manufacturing technique

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9144a07f-41a4-4951-af3d-2ec2d9ca7ec6/download

null

y layer, volumetric additive manufacturing produces the whole geometry at the same time. While it is faster, creates features with high surface quality, requires no overhang support structures, and can print in high-viscosity resins, all of which push the limits of additive manufacturing, this technique is still premature and suffers from some effects such as body sedimentation that impacts the geometric fidelity and resolution of the final product. The sedimentation rate of the printed body during its formation is highly dependent on the resin type, its viscosity, and its curing behavior. Herein, we propose a CFD model that takes into account the synergistic effect of reaction-based heating, curing behavior, and resin properties to predict the sedimentation rate of the printed geometry. The results show that heating effects can slow down the sedimentation rate of the curing part significantly.

null

['Galimberti, G.', 'Doubrovski, E.L.', 'Guagliano, M.', 'Previtali, B.', 'Verlinden, J.C.']

2021-11-01T22:26:17Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89782

eng

2016 International Solid Freeform Fabrication Symposium

Open

['process parameters', 'aesthetic properties', 'selective laser melting', '3D printing']

Investigating the Links Between the Process Parameters and Their Influence on the Aesthetic Evaluation of Selective Laser Melted Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0ed62e24-750d-4d5b-aa6d-8cb498437f23/download

University of Texas at Austin

This study is a precursor to gaining a deeper understanding of how each parameter of the Additive Manufacturing (AM) process influences the aesthetic properties of 3D printed products. Little research has been conducted on this specific aspect of AM. Using insights from the work presented in this paper, we intend to develop design support tools to give the designer more control over the printed products in terms of aesthetics. In this initial work, we fabricated samples using Selective Laser Melting (SLM) technology, and investigated the parameters geometry, building strategy, and post-processing. We asked participants to evaluate the visual and physical interaction with the manufactured samples. Results show that, in addition to geometry and post-processing, the aesthetic evaluation can also be strongly influenced by the SLM process’ building strategy. This understanding will enable us to develop tools to give designers more control over the part’s aesthetic appearance. In addition, we present a systematic procedure and setup to evaluate the aesthetic appearance of products manufactured using AM.

null

['Woods, E.', 'Fromhold, M.', 'Wildman, R.', 'Tuck, C.']

2021-11-30T22:09:10Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90566', 'http://dx.doi.org/10.26153/tsw/17485']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['gradient index optics', 'modulation', 'two-photon polymerization']

Investigating the Production of Gradient Index Optics by Modulating Two-Photon Polymerisation Fabrication Parameters

Conference paper

https://repositories.lib.utexas.edu//bitstreams/92e0bd59-fa8b-43a4-ac37-d40d8eb1c47b/download

University of Texas at Austin

Two-photon polymerisation (TPP) is an additive manufacturing technique allowing the fabrication of arbitrary 3D geometries with sub-micron features. As such, TPP is a promising technique for fabricating optical metamaterials. The electromagnetic (EM) properties of metamaterials arise from their geometrical structure rather than their material constituents alone. By introducing variations across the unit cells of a metamaterial spatially varying EM properties can be created. In this way, gradient index (GRIN) optics can be produced which are useful for reducing coupling losses and creating compact optical systems. This work looks at modulating fabrication parameters to achieve geometrical variations. Line widths of IP-L 780 are measured on an array of lines fabricated at different laser powers and scan speeds. Proof of concept woodpile structures are also fabricated where laser power is changed for individual lines in the structure resulting in geometrical changes. Changing fabrication parameters along a single scan line is also investigated.

null

['Sampson, Bradley J.', 'Morgan-Barnes, Courtney', 'Stokes, Ryan', 'Doude, Haley', 'Priddy, Matthew W.']

2023-01-27T13:34:20Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117328', 'http://dx.doi.org/10.26153/tsw/44209']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Laser powder bed fusion', 'selective laser melting', 'in-situ process monitoring', 'Ti6Al4V', 'thermal monitoring', 'additive manufacturing']

Investigating the Relationship Between In-Process Quality Metrics and Mechanical Response in the L-PBF Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d58c3266-ee30-4513-a89f-9a639882fd2c/download

null

Laser powder bed fusion (L-PBF) additive manufacturing is a process that utilizes a high- powered laser to build near net-shaped parts in a layer-by-layer fashion using metal powder as the feedstock material. Traditionally, the analysis of L-PBF produced parts has relied solely on post- build characterization to understand the relationship between the printing process and the final mechanical properties. Recent developments of in-process quality assurance systems, such as Sigma Additive Solutions’ PrintRite3D, can measure in-process thermal signatures and melt pool disturbances in real-time. This research aims to examine the relationship between process parameters (e.g., scan strategy, scanning speed, and layer thickness) and in-process quality metrics (IPQMs) captured by the PrintRite3D system on a Renishaw AM400. The mechanical response of multiple part geometries (NIST residual stress bridges, single-arched bridges) and build materials (Ti6Al4V) includes residual stress deflection and hardness; the results are compared with the IPQMs.

null

['Snarr, Patrick L.', 'Beaman, Joseph', 'Haas, Derek']

2021-12-06T21:20:58Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90675', 'http://dx.doi.org/10.26153/tsw/17594']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['indirect selective laser sintering', 'thermally induced phase separation']

Investigating Thermally Induced Phase Separation as a Composite Powder Synthesis Technique for Indirect Selective Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e21868d3-a79b-4b22-9915-dc4a7e45eb58/download

University of Texas at Austin

The nuclear energy and nuclear defense industries have long relied on traditional manufacturing techniques for fabrication of reactor and weapon components. With the recent growth of additive manufacturing (AM), the nuclear industry is now asking the question of how AM could be used to manufacture components found in the nuclear fuel cycle. Many important components in the nuclear fuel cycle are made from ceramics, including the popular fuel, uranium oxide. This research investigates an indirect selective laser sintering technique (iSLS) that can be used to fabricate complex ceramic components. Thermally induced phase separation (TIPS) was explored as a technique to coat ceramic particles with a polymer, which can then be employed in an indirect SLS method. Two process variables of TIPS were studied, and the resulting powder characterized.

null

['Tang, Shangyong', 'Wang, Guilan', 'Huang, Cheng', 'Zhang, Haiou']

2021-11-18T01:12:06Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90386', 'http://dx.doi.org/10.26153/tsw/17307']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['WAAM', 'additive manufacturing', 'arc striking', 'arc extinguishing', 'abnormal area', 'bead geometry']

Investigation and Control of Weld Bead at Both Ends in WAAM

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3594fd39-2478-40fd-8942-103d224228a0/download

University of Texas at Austin

Control of bead geometry in wire and arc additive manufacturing is significant as it effect the whole manufacturing process. However, the weld beads at arc striking and arc extinguishing area are generally abnormal in which the dynamical process of the weld bead is unstable. In this paper, the abnormal areas in arc striking and arc extinguishing point were investigated. Different parameters were used to make the width and height closed to the middle area in the AS and AE point. A burning-back method was proposed to fill up the slant plane in AE point. Experiments were conducted to study and verify the abnormal areas of the weld bead. And the experimental result indicated that the methods at both ends were available and preferable in the optimization of weld beads.

null

['Montgomery, J.', 'Vaughan, M.', 'Crawford, R.']

2021-09-29T17:25:46Z

2009-09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88194', 'http://dx.doi.org/10.26153/tsw/15135']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['lower-leg prosthetic socket', 'adaptive sockets', 'selective laser sintering', 'additive manufacturing']

Investigation and Design of an Actively Actuated Lower-Leg Prosthetic Socket

Conference paper

https://repositories.lib.utexas.edu//bitstreams/089d6372-ed8d-41e0-a520-cb6c8c742d25/download

University of Texas at Austin

A prosthetic socket worn by an amputee must serve a wide variety of functions, from stationary support to the transfer of forces necessary to move. Fit and comfort are important factors in determining the therapeutic effectiveness of a socket. A socket that does not fit the subject well will cause movement problems and potentially long-term health issues. Because a subject's residual limb changes volume throughout the day, it is desirable that the socket adapt to accommodate volume changes to maintain fit and comfort. This paper presents research to manufacture adaptive sockets using selective laser sintering (SLS). This additive manufacturing process allows freedom to design a socket that has both compliant areas that can adapt to changes to the residual limb, as well as rigid regions to provide necessary support for the limb. A variety of concepts are discussed that are intended for manufacture by SLS, and that feature flexible inner membranes in various configurations. For each concept the membrane will be inflated or deflated to match the limb’s change in volume. and the paper also presents a study to determine SLS machine parameters for optimal build results, as well as results from initial pressure-deflection experiments.

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