ccm/sff-papers · Datasets at Hugging Face

['Roy, N.K.', 'Cullinan, M.A.']

2021-10-19T18:11:26Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89314

eng

2014 International Solid Freeform Fabrication Symposium

Open

['nanopowders', 'powder spreading', 'actuating system', 'powder bed', 'μ-SLS']

μ-SLS of Metals: Design of the Powder Spreader, Powder Bed Actuators and Optics for the System

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e7c270bf-07d5-4ac4-8554-3b5ac721e8ca/download

University of Texas at Austin

Nanopowders have a tendency to form agglomerates due to high surface energy and the presence of attractive van der Waals forces. To overcome this problem, we present a powder spreading mechanism design that can alleviate this phenomenon by using vibration compaction to produce a uniform powder distribution in the bed. Most SLS machines employ either a roller or a blade to spread the powder over the powder bed. However, in order to achieve layer thicknesses of few microns, a new design for the spreading mechanism which includes a combination of a precision blade and a precision roller is employed. Also, the design of a linear actuating system for displacing the powder bed with resolution of few tens of nanometers is presented for the μ-SLS system. Finally, the paper presents a novel optical system that can drastically increase the throughput of the system .The detailed design of these systems are presented in this paper.

null

['Roy, N.K.', 'Yuksel, A.', 'Cullinan, M.A.']

2021-10-20T22:33:47Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89377

eng

2015 International Solid Freeform Fabrication Symposium

Open

['micro-scale selective laser sintering', 'μ-SLS', 'nanopowders', 'copper', 'particle size', 'density']

μ-SLS of Metals: Physical and Thermal Characterization of Cu- Nanopowders

Conference paper

https://repositories.lib.utexas.edu//bitstreams/44872607-430d-4595-8cb4-37740d20f7ba/download

University of Texas at Austin

Micro-scale selective laser sintering(μ-SLS) requires the use of nanoparticles(NPs) since the particle size needs to be an order of magnitude smaller than the melt pool in order to accurately sinter particles together to form a part. Most NPs properties are dependent upon size and thus, an exhaustive study of the physical and thermal properties of these NPs is required in order to successfully model and simulate the sintering process. In this paper we will present particle size characterization using Scanning electron microscopy (SEM), density measurements using He pycnometry, and X-ray Energy Dispersive Spectroscopy that were carried out to characterize the copper(Cu) nanopowder samples. Furthermore, the samples were sintered with different powers to estimate optimum power and exposure times and the results have been discussed along with further scope of work for fully characterizing the particles.

null

['Wächter, Julian', 'Elsner, Maike', 'Moritzer, Elmar']

2021-11-18T01:51:17Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90401', 'http://dx.doi.org/10.26153/tsw/17322']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['PEEK', 'processability', 'weld seam strength', 'fused deposition modeling']

Investigation of the Processability of Different PEEK Materials in the FDM Process with Regard to the Weld Seam Strength

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a36b468c-7062-476b-87f8-582433c28b95/download

University of Texas at Austin

Due to the great popularity of the Fused Deposition Modeling (FDM) process, the material market is growing. In particular, processing of high-temperature materials such as PEEK is demanding. The aim of the investigations is to test different PEEK materials regarding their processability in the FDM process. An unreinforced PEEK, a thermally conductive PEEK as well as a carbon fiber reinforced PEEK are investigated. The processability is assessed with the help of the weld seam strength. The assessment of the weld seam strength is carried out by building tests. For this purpose, a special method developed at the DMRC is used. In addition, a welding width factor between the strands deposited on each other is calculated and compared. Finally, a welding factor is determined to enable the comparison between the different materials. With this procedure, the influences of varying nozzle and build chamber temperatures on the achievable weld seam strengths are evaluated.

null

['Wimmer, Marco', 'Kemnitzer, Jan', 'Forster, David', 'Schorzmann, Johann', 'Dopper, Frank']

2024-03-25T22:24:38Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124320', 'https://doi.org/10.26153/tsw/50928']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['HSS', 'PBF-P', 'PEBA', 'additive manufacturing']

Investigation of the Processability of Polyether Block Amide in High Speed Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/676a37fd-aab9-4e08-832f-4c0d8c96a018/download

University of Texas at Austin

The High Speed Sintering (HSS) process ranks among the processes of Powder Bed Fusion of polymers (PBF-P) of Additive Manufacturing (AM). Its scalability, constant layer time and high quality of complex parts compared to other AM processes are some of the characteristics of the HSS showing its potential for series production for small to medium series. Most of the investigations for the PBF-P processes were conducted using commercially available materials like Polyamide 12 (PA12), Polyamide 6 (PA6), Thermoplastic polyurethane (TPU), Polypropylene (PP) and Polybutylene terephthalate (PBT). This work reports from the processing of Polyether block amide (PEBA) in HSS. As a block-copolymer on amide basis, PEBA shows higher performance compared to other block-copolymers like TPU: The high elastic properties, low density and high service temperature make PEBA an ideal material for the use in the athletic footwear and outdoor industry. Until now, no research was conducted on processing PEBA powder in HSS. This work focusses on the material analysis of PEBA powder and manufacturing of specimens of varying sets of process parameters using methods of Design of Experiments (DoE) and IFINAM TPA powder from Evonik. Based on a predictive model, parameter sets for optimum mechanical properties, dimensional accuracy and overall part properties of HSS PEBA parts were optimised within the framework of this work.

null

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

2021-12-06T22:34:18Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90700', 'http://dx.doi.org/10.26153/tsw/17619']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['laser powder bed fusion', 'reinforcement', 'IN718', 'microstructure', 'Vickers hardness']

Investigation of the Properties of Reinforced IN718 Structures Fabricated using Laser Powder Bed Fusion

Conference paper

https://repositories.lib.utexas.edu//bitstreams/25885333-3604-4965-88c2-b64a4f0031b7/download

University of Texas at Austin

Inconel 718 (IN718) superalloy, known for its high strength and corrosion resistant behavior, is widely used in the aerospace and automotive industries. Laser power bed fusion (LPBF), one of the commonly used techniques of additive manufacturing, enables the fabrication of structures with a variety of local properties. Using the same material, components with spatially varying properties can be fabricated through applying different processing parameters. In this study, IN718 composite structures were fabricated using four types of rod reinforcements with different geometry. A different set of process parameters was used to fabricated reinforcing rods compared to that of the main part. The bonding quality at the interface between the main part and reinforcements was determined by defect analysis on the microstructure results. Also, Vickers hardness test was performed at the interface in order to examine the mechanical properties of the samples. It was found out that a similar level of densification and hardness value, slightly less than the plain sample, can be achieved using helical and arc reinforcing rods. By contrast, significantly lower density and hardness were observed for the sample reinforced by square rods compared to the plain sample.

null

['Zhou, Y.', 'Zhou, X.', 'Teng, Q.', 'Wei, Q.S.', 'Shi, Y.S.']

2021-10-20T21:53:28Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89371

eng

2015 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', '316L stainless steel', 'Inconel 718', 'functionally graded materials', 'powder bed', 'powder feed']

Investigation of the Scan Strategy and Property of 316L Stainless Steel-Inconel 718 Functionally Graded Materials Fabricated by Selective Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4883d255-505a-4a17-ba72-520e877df0fc/download

University of Texas at Austin

316L stainless steel and Inconel 718 alloy functionally graded materials were fabricated by selective laser melting with a novel approach which combined powder-bed with powder-feed pattern. Two different scanning strategies have been used to form the steel/Ni FGMs. The interfacial characteristics were analyzed by scanning electron microscopy and energy dispersive spectroscopy. Quantitative evidence of good bonding at the interface was obtained from the tensile and shear tests of the steel/Ni FGMs.

null

['Yang, Li', 'Haijun, Gong', 'Dilip, Samuel', 'Stucker, Brent']

2021-10-13T21:02:45Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88784', 'http://dx.doi.org/10.26153/tsw/15718']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['thin features', 'direct metal laser sintering', 'lightweight structures', 'additive manufacturing']

An Investigation of Thin Feature Generation in Direct Metal Laser Sintering Systems

Conference paper

https://repositories.lib.utexas.edu//bitstreams/067fe6bb-ad91-4a5b-aa22-6839005cfb61/download

University of Texas at Austin

The fabrication of metal structures with thin features (<1mm) with additive manufacturing processes is of interest for various lightweight applications. This paper investigates the geometrical and microstructural characteristics of thin features fabricated using an EOS direct metal laser sintering (DMLS) system. Both 1D and 2D thin features were fabricated using various process themes, and subsequently analyzed for microstructure geometrical characteristics. It was found that the selection of process parameters has significant influence on both the geometrical accuracy and the microstructure of the thin features. The results can be used for the further development of process guidelines for lightweight structures such as cellular structures and support structures.

null

['Fan, Foxian', 'Jalui, Sagar', 'Lajoie, Nicholas', 'Manogharan, Guha']

2023-02-10T14:27:02Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117454', 'http://dx.doi.org/10.26153/tsw/44335']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['AM Post-Processing', 'AM Areal Surface Roughness', 'Mass Finishing', 'Centrifugal Disc Finishing', 'AM Wear Behavior', 'Hybrid Manufacturing']

Investigation of Wear Behavior of Centrifugal Disc Finishing on Additively Manufactured Ti6Al4V Samples

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ef4d9b99-5f74-441d-a9dc-0660cbfba0d2/download

null

As-built Additively Manufactured (AM) metallic parts require secondary processing in most applications to improve surface finish and mechanical strength. Mass Finishing (MF) processes are gaining popularity as effective and economical surface improvement methods for metal AM parts. This study investigates the wear behavior of post-processing both Laser Powder Bed Fusion (LPBF) and Electron Beam Melting (EBM) fabricated Ti6Al4V parts via Centrifugal Disc Finishing (CDF). Both AM orientation-based surface finish and wear behavior are compared for better understanding on key mechanisms of AM+MF hybrid manufacturing system. The areal surface roughness results showed that wear rate on side surfaces were higher than top surfaces for both LPBF and EBM samples in CDF. In addition, LPBF samples exhibited higher material removal than EBM samples based on weight loss measurements.

null

['Mollah, Md. Tusher', 'Moetazedian, Amirpasha', 'Gleadall, Andy', 'Yan, Jiongyi', 'Alphonso, Wayne Edgar', 'Comminal, Raphaël', 'Šeta, Berin', 'Lock, Tony', 'Spangenberg, Jon']

2023-01-26T15:51:41Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117321', 'http://dx.doi.org/10.26153/tsw/44202']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Microscale Corner Precision', 'Bowden and Direct-drive Extruders', 'Experiments', 'Computational Fluid Dynamics', 'Material Extrusion Additive Manufacturing']

Investigation on corner precision at different corner angles in material extrusion additive manufacturing: An experimental and computational fluid dynamics analysis

Conference paper

https://repositories.lib.utexas.edu//bitstreams/333c6c2a-64c3-407c-84e3-e1b4c91ac515/download

null

This paper investigates the influence of different corner angles on microscale geometry in material extrusion additive manufacturing. Polylactic acid (PLA) was 3D-printed with corner angles of 15°, 30°, 45°, 60°, 75°, 90°, and 135° using Bowden and Direct-drive extruders. A computational fluid dynamics (CFD) model was developed to simulate the polymer flow through the extrusion nozzle of both extruders. The simulated corner geometries were compared with experiments to assess simulation accuracy. This included the primary and secondary mitre cross-sectional width through the corner point of the 3D-printed strands. This enabled a new understanding about the prediction accuracy of the CFD model as well as the state of material at the corners, and the deviation of experimental and simulated corners from the analytical one. Moreover, the amount of over- and under-extrusion around the corner was estimated for experimental and simulated studies compared with the analytical corner, which provided fundamental knowledge on corner precision for angular print paths.

null

['Yasa, Evren', 'Deckers, Jan', 'Craeghs, Tom', 'Badrossamay, Mohsen', 'Kruth, Jean-Pierre']

2021-09-28T19:19:35Z

9/15/09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88158', 'http://dx.doi.org/10.26153/tsw/15099']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', 'elevated ridges', 'elevated edges', 'successive layers']

Investigation on Occurrence of Elevated Edges in Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8e3b3ebd-22bb-433a-83b9-a918b3a27871/download

University of Texas at Austin

Selective laser melting (SLM) is a layer-wise material additive process for the direct fabrication of functional metallic parts. During the process, successive layers of metal powder are fully molten and consolidated on top of each other by the energy of a high intensity laser beam. The process is capable of producing almost fully dense three-dimensional parts having mechanical properties comparable to those of bulk materials. However, one of the problems encountered in SLM process is the occurrence of elevated ridges of the solidified material at the edges of the successive layers. Those ridges reduce the dimensional accuracy and topology of the top surface. The edge-effect problem is encountered not only in SLM, but also in other production techniques applying melting processes such as LENS® (The Laser Engineered Net Shaping) and EBM (Electron Beam Melting). In this study, the reasons for elevated edges and solutions to this problem are investigated and reported. Different scan strategies as well as different hatching and contour parameters are tested to reduce the edge-effect problem. Besides, the influence of applying laser re-melting in combination to selective laser melting has been investigated. It turns out that re-melting layers deposited by SLM improves the part density and surface roughness, but creates on its own elevated edges.

null

['Deng, Dongping', 'Chen, Yong', 'Zhou, Chi']

2021-10-06T20:42:30Z

2012

Mechanical Engineering

null

['https://hdl.handle.net/2152/88439', 'http://dx.doi.org/10.26153/tsw/15376']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['PEEK composite', 'mask projection stereolithography', 'slurry recoating', 'sintering']

Investigation on PEEK Fabrication Using Mask-image-projection-based Stereolithography

Conference paper

https://repositories.lib.utexas.edu//bitstreams/cfe87725-aa7a-428c-aff0-83c49414c95b/download

University of Texas at Austin

This paper presents the findings of an initial study of the fabrication of polyetheretherketone (PEEK) components based on the mask-image-projection-based Stereolithography (MIP-SL) process. PEEK is a semicrystalline thermoplastic with excellent mechanical and chemical resistance properties that are retained to high temperatures. It has been extensively used in the aerospace, automotive, biomedical, and chemical process industries. The fabrication process based on the MIP-SL includes both green-part fabrication and the sintering of fabricated green parts. In the green part fabrication, the challenges of recoating viscous composite slurry are discussed. A prototype system has been developed for the fabrication of green-parts with complex shapes and small features. Based on the fabricated green-parts, the challenges in the sintering process for achieving desired functionality are discussed. The test results on the sintered PEEK components have also been presented. Future work based on the study has been identified.

null

['Praniewicz, M.', 'Fox, J.', 'Saldana, C.']

2021-12-01T23:17:39Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90652', 'http://dx.doi.org/10.26153/tsw/17571']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['lattice structures', 'definition', 'qualification', 'additive manufacturing']

An Investigation on the Definition and Qualification of Form on Lattice Structures

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c6721a9d-53b6-4402-872a-1d0c0f0fc69d/download

University of Texas at Austin

The lack of uniform qualification techniques for additively manufactured components throughout industry currently limits their application in high risk environments. This stems from a shortage of proper tolerancing and product definition to convey design intent and required qualification. This definition is particularly difficult for complex lattice geometries. The results of studies in which the form of a lattice component is defined by theoretical supplemental surfaces are summarized, with specific attention to the role of data sampling in the evaluation of form. A new case study is presented where techniques borrowed from surface metrology, namely the construction of a bearing area curve, are used to evaluate the sampling cutoff for form evaluation. This method is first validated on the nominal geometry of three lattice designs. Initial results indicate this as a promising methodology.

null

['Liu, Bochuan', 'Tuck, Christopher', 'Saleh, Ehab', 'Ashcroft, Ian', 'Wildman, Ricky', 'Hague, Richard']

2021-10-12T20:30:54Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88734', 'http://dx.doi.org/10.26153/tsw/15668']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['multi-functionality', 'multi-layer', 'conductive tracks', 'inkjet printing']

Investigation on the Performance of Multi-Layer Printed Conductive Tracks on Multi-Layer Printed Insulator

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b9c4f77b-7150-4eff-bd37-457f16051091/download

University of Texas at Austin

The move to multi-functionality in Additive Manufacturing converges a number of technical challenges, notably the accurate and reliable deposition of different materials and their interaction. In this paper, an investigation on the pattern quality and conductivity of multi-layer printed conductive tracks on multi-layer 3D printed insulator was carried out using a drop-on-demand inkjet technique. Results have shown that the surface finish of the printed insulator had a significant effect on the performance of the conductive tracks that have been overlaid. Also the printing strategy used in the processing resulted different width, height, conductivity and pattern quality of multi-layer printed conductive tracks.

null

['Goulas, Athanasios', 'Southcott-Engstrøm, Daniel', 'Friel, Ross J.', 'Harris, Russell A.']

2021-11-01T22:03:04Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89772

eng

2016 International Solid Freeform Fabrication Symposium

Open

['extra-terrestrial materials', 'additive manufacturing', '3D printing']

Investigation the Additive Manufacture of Extra-Terrestrial Materials

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3dcf26af-83a2-4ccf-bf84-814aa324b829/download

University of Texas at Austin

The Powder Bed Fusion (PBF) additive manufacturing process category, consists of a group of key enabling technologies allowing the fabrication of both intrinsic and complex structures for a series of applications, including aerospace and astronautics. The purpose of this investigation was to explore the potential application of in-space additive manufacturing/3D printing, for onsite fabrication of structures and parts, using the available extra-terrestrial natural resources as feedstock. This study was carried out by using simulants of terrestrial origin, mimicking the properties of those respective materials found extra-terram (in space). An investigation was conducted through material characterisation, processing and by powder bed fusion, and resultant examination by analytical techniques. The successful realisation of this manufacturing approach in an extra-terrestrial environment could enable a sustainable presence in space by providing the ability to build assets and tools needed for long duration/distance missions in deep space.

null

['Liu, Bochuan', 'Wildman, Ricky', 'Tuck, Christopher', 'Ashcroft, Ian', 'Hague, Richard']

2021-10-04T21:24:29Z

2011

Mechanical Engineering

null

['https://hdl.handle.net/2152/88351', 'http://dx.doi.org/10.26153/tsw/15290']

eng

2011 International Solid Freeform Fabrication Symposium

Open

['particle size distribution', 'powder bed', 'processing paramters', 'quality of finishing parts', 'Selective Laser Melting']

Investigation the Effect of Particle Size Distribution on Processing Parameters Optimisation in Selective Laser Melting Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c1438596-fbb8-4e28-ada8-6fa82077e1c5/download

University of Texas at Austin

Selective Laser Melting is an efficient process for producing metal parts with minimal subtractive post-processing required. Analysis of the parameters controlling the part quality has been performed focusing on the energy intensity during processing and the effect of the particle size distribution on factors such as ultimate tensile strength and surface finish. It is shown that the controlling the energy intensity is key to quality and can be affected by varying, for example, laser beam diameter or the scanning rate.

null

['Weiss, C.', 'Munk, J.', 'Haefner, C.L.']

2021-12-06T21:53:56Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90686', 'http://dx.doi.org/10.26153/tsw/17605']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['powder behavior', 'AlSi10Mg', 'recyclability', 'laser powder bed fusion', 'LPBF']

Investigation Towards AlSi10Mg Powder Recycling Behavior in the LPBF Process and Its Influences on Mechanical Properties

Conference paper

https://repositories.lib.utexas.edu//bitstreams/63f96a6f-f108-4ad9-b635-fd3e303a3aa0/download

University of Texas at Austin

Parts fabricated by Laser Powder Bed Fusion (LPBF) technique allow for a high material utilization of a single powder batch, since unfused powder material can be reconditioned and reused in subsequent manufacturing jobs. Due to process induced spatters however, the quality of the powder may change during recycling, which in turn can affect the mechanical properties of built parts. Therefore, a better understanding on the recyclability of the powder material is needed. Within this work, the powder ageing behavior of the lightweight aluminum alloy AlSi10Mg in the LPBF process is investigated. A standard build job is developed and built with ageing powder in 10 consecutive jobs with no refreshing between the cycles. The powder properties as well as the mechanical properties at static load for two different build orientations are investigated. The comprehensive analyses suggest that the powder coarsening may lead to improved mechanical properties during recycling for AlSi10Mg.

null

['Krischke, N.', 'Friedmann, M.', 'Fleischer, J.']

2023-03-30T16:18:03Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117701', 'http://dx.doi.org/10.26153/tsw/44580']

eng

2022 International Solid Freeform Fabrication Symposium

Open

ARBURG

Investigations for the Optimization of Metal Freeforming using the ARBURG freeformer

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3d704f8a-532b-4bc3-b8e5-808b1fd8e24e/download

null

The ARBURG freeformer represents an additive manufacturing system for producing thermoplastic components using commercially available polymer granulate. This fabrication process offers the potential to use feedstocks known from the metal injection molding (MIM) sector to manufacture so-called green parts. These parts consist of 60 Vol.-% stainless steel powder and 40 Vol-% organic polymer binding system. By debinding and sintering these green parts, it is possible to economically produce full metal components with mechanical properties comparable to metal injection molding. In this publication, the process of producing stainless steel parts with ARBURG plastic freeforming will be presented. The mechanical properties and part density are optimized by varying manufacturing parameters and raw materials. Furthermore, concepts to optimize and increase the service life of the nozzle are shown and discussed. An increase of at least 250% could be achieved by plasma nitriding and coating components of the discharge system.

null

['Hecker, F.', 'Elsner, C.L.', 'Hirsch, A.', 'Moritzer, E.']

2021-12-01T23:04:41Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90648', 'http://dx.doi.org/10.26153/tsw/17567']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['arburg plastic freeforming', 'visual properties', 'geometrical properties', 'process parameters', 'optimization']

Investigations for the Optimization of Visual and Geometrical Properties of Arburg Plastic Freeforming Components

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8d15d057-264b-41ff-8ac5-beaa5df1ebe2/download

University of Texas at Austin

Arburg Plastic Freeforming (APF) is an additive manufacturing process with which three-dimensional, thermoplastic components can be produced layer by layer. Visual and geometrical properties are a major criterion for characterizing the resulting component quality. The aim of this study was to investigate the influences on visual and geometrical properties of APF components depending on process parameters. Initially the focus was on the analysis of the shrinkage behavior of ABS-M30 (Stratasys). On the basis of the results and an existing procedure by the machine manufacturer, an optimized procedure for determining the scaling factors was developed to counteract the shrinkage. With this procedure a higher dimensional accuracy of the components can be achieved. In addition, it was investigated whether an adaption of the form factor based on a mathematical model depending on the component geometry makes sense. The results were transferred into manufacturing guidelines, which allow the user of the APF-technology to optimize process parameters more efficiently.

null

['Jiang, Jinhui', 'Yuan, Mengqi', 'Ji, Tingchao']

2021-11-01T21:35:32Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89761

eng

2016 International Solid Freeform Fabrication Symposium

Open

['stab resistance body armor', 'laser sintering', 'structure', 'pyramid']

Investigations on Laser Sintered Textiles for Stab-Resistant Application

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f1697458-0b40-4329-8b39-da37a80d3612/download

University of Texas at Austin

Stab resistance body armor (SRBA) is essential in protecting people from knife injuries. The protective parts of traditional SRBA are made of multi-layered ultra-high molecular weight polyethylene, which causes heavy heat stress for people wearing it. In this paper, the protective parts of SRBA were manufactured using laser sintering (LS) technology, which provide high manufacturing flexibility as well as high wearing comfort. Two different structures were investigated, one is squared plate and the other is pyramid. It was found the pyramid structure showed much higher stab resistance property then the plate, which is a result from the angle and thickness effects. This paper is the first effort applying the technology of LS and material of PA 3200 on SRBA, and by applying the pyramid structure on the protective layer of the SRBA, the total weight could reduce 30-40%.

null

['Vora, P.', 'Derguti, F.', 'Mumtaz, K.', 'Todd, I.', 'Hopkinson, N.']

2021-10-11T20:34:34Z

2013

Mechanical Engineering

null

['https://hdl.handle.net/2152/88634', 'http://dx.doi.org/10.26153/tsw/15568']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['Additive Manufacturing', 'Selective Laser Sintering', 'Electron Beam Melting', 'metal powder bed', 'in-situ alloy', 'semi-solid processing']

Investing a Semi-Solid Processing Technique Using Metal Powder Bed Additive Manufacturing Processes

Conference paper

https://repositories.lib.utexas.edu//bitstreams/306d6f58-a927-41df-a64a-8d4e64d27cf6/download

University of Texas at Austin

The work reported investigates in-situ alloying using a semi-solid processing technique with metal powder bed Additive Manufacturing (AM); in this instance Selective Laser Melting (SLM) and Electron Beam Melting (EBM) were employed. This technique utilised customised powder blends that were processed at elevated temperatures. The selection of processing temperature considered specific alloy solidification ranges. As a result, parts with reduced residual stresses can be produced. In addition, the use of customised powder blends explored the feasibility of developing alloys specific to the process/application, thus increasing available material ranges for AM metal powder bed processes.

null

['Zhang, Wei', 'Leu, Ming C.', 'Feng, Chao', 'Ren, Rong', 'Zhang, Renjie', 'Lu, Qingping', 'Jiang, Jubu', 'Yan, Yongnian']

2019-09-20T18:10:13Z

2000

Mechanical Engineering

null

['https://hdl.handle.net/2152/75921', 'http://dx.doi.org/10.26153/tsw/3020']

eng

2000 International Solid Freeform Fabrication Symposium

Open

Prototyping

Investment Casting with Ice Patterns Made by Rapid Freeze Prototyping 66

Conference paper

https://repositories.lib.utexas.edu//bitstreams/82130586-75c0-4c20-8897-357fc53652fb/download

null

One of the most promising applications of rapid freeze prototyping (RFP) is making metal parts by investment casting with the built ice parts. The integration of RFP and investment casting allows fast creation of complex net-shape metal parts directly from their CAD models. The advantages of doing so include no part geometric complexity limitation, no experience of parting line design and assembling needed, clean and low-cost of process operation, and good performance. In this paper, we will present our recent study on binder selection, slurry making, ceramic shell making, and the casting results of the metal parts.

null

['Lombardi, John L.', 'Hoffinan, Robert A.', 'Waters, Jason A.', 'Popovich, Dragan']

2018-12-05T20:35:18Z

1997

Mechanical Engineering

doi:10.15781/T20K26X7N

http://hdl.handle.net/2152/71415

eng

1997 International Solid Freeform Fabrication Symposium

Open

['FDM', 'EFF']

Issues Associated with EFF & FDM Ceramic Filled Feedstock Formulation

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6207970d-7d8d-4791-b1ad-e2670ba99380/download

null

['Paggi, Umberto', 'Ranjan, Rajit', 'Thijs, Lore', 'Ayas, Can', 'Langelaar, Matthijs', 'van Keulen, Fred', 'van Hooreweder, Brecht']

2021-11-18T18:50:12Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90465', 'http://dx.doi.org/10.26153/tsw/17386']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['support structures', 'contactless support', 'overheating', 'downfacing regions', 'laser powder bed fusion']

New Support Structures for Reduced Overheating on Downfacing Regions of Direct Metal Printed Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6e17ba55-1200-4e93-bbc5-83f299542d11/download

University of Texas at Austin

In Laser Powder Bed Fusion (LPBF), the downfacing surfaces usually have increased surface roughness and reduced dimensional accuracy due to local overheating and warpage. To partially overcome this a new supporting structure is developed in this study, namely the contactless support. This is a thin blade parallel to the critical area which transfer the heat away from the melt pool via conduction through the powder bed instead of direct contact. The support is tested in different geometries and printing conditions to define the optimal distance from the part and its effectiveness is evaluated by measuring the surface roughness of the samples. Numerical modelling of heat transfer phenomenon is also employed to determine the thermal history of the printing process and understand which parameters define the optimal distance for the thermal supports. Finally topology optimization is used to create a support structure which minimize the wasted material while keeping the heat flow optimal.

null

['Jandric, Z.', 'Kovacevic, R.']

2019-10-09T16:20:52Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76154', 'http://dx.doi.org/10.26153/tsw/3243']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Optimization

New Way of Process Parameters Optimization in SFF Based on Deposition by Welding

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e4e244c3-026a-4c9d-8b38-bebdf2a07a25/download

null

To successfully control the welding process and to make it appropriate for solid freeform fabrication (SFF), it is necessary to fully understand the influence of the welding parameters and the geometry of the substrate on the resulting weld bead dimensions. Extensive experiments with different welding parameters and complex geometrical features such as edges and corners have been designed and completed. The experimental data show a clear correlation between the heat input, the weld bead dimensions, and the two dimensional (2D) geometrical features. This correlation may be used for on-line welding process control. It is found that the geometry of the molten pool is directly related to the heat transfer conditions determined by surrounding mass of material. A machine vision system based on a high-resolution CCD camera coaxially integrated with a gas tungsten arc welding (GTAW) torch is used to acquire the images of the molten pool. The results demonstrate the capability to adjust GTAW process parameters according to complex external and internal geometrical features of the substrate. The heat loss affected by the surrounding mass of material will be used to determine the optimal energy input.

This work was financially supported by THECB, Grant No. 003613-0022001999, NSF, Grants No. DMI – 9732848 and DMI – 9809198, and the U.S. Department of Education, Grant No. P200A-80806-98.

null

['Plocher, J.', 'Panesar, A.']

2021-11-09T19:55:13Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90147', 'http://dx.doi.org/10.26153/tsw/17068']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['beam compliance', 'three-point bending', 'topology', 'fiber orientation', 'lightweight structures', 'fused deposition modeling', 'additive manufacturing']

Next-Generation Fibre-Reinforced Lightweight Structures for Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9f9cd531-1f2d-41e9-abfa-fddec79ecbd5/download

University of Texas at Austin

In an attempt to realise next-generation lightweight parts and to fully utilize the inherent design freedom of AM, we propose a topology optimization based design procedure that includes the anisotropic considerations for continuous fibre printing of variable stiffness composites. In this paper, we aim to improve the normalized compliance of a beam in a three-point bending scenario, using a skeletal reinforcement for a topology in which the change in fibre orientation is derived from the medial axis information. FDM with a dual-nozzle system printing nylon and carbon fibre filaments were utilized for fabrication. The toolpath i.e. reinforcement strategy available from the commercial software Eiger® was chosen to imitate the proposed strategy. The numerical investigation is complemented with experimental tests and a general benchmarking is conducted using standard pedants. The results have shown improved specific flexural stiffness for samples with skeletal reinforcement. The skeletal information is therefore considered as important tool for the retrieval of fibre angles which align with the principle stresses and therefore allow for a more efficient fibre placement in AM parts for future lightweight end-use parts.

null

['Melvin III, Lawrence S.', 'Beaman Jr., Joseph J.']

2018-11-08T15:37:28Z

1995

Mechanical Engineering

doi:10.15781/T2KK94Z19

http://hdl.handle.net/2152/69890

eng

1995 International Solid Freeform Fabrication Symposium

Open

['selective laser sintering', 'intermediate temperature', 'powder application']

Nickel Applied for Selective Laser Sintering Using a Magnetic Field

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1648bcb6-ba34-4694-94ea-e6df7f963c7a/download

null

Metal powder was applied for the Selective Laser Sintering process using the sieve feed system and a magnetic field. The magnetic field had a negative effect on final part quality as measured by a reduction in final part density. This negative effect is theorized to be due to the shape and orientation ofthe magnetic field. It appears possible to change the field to a benevolent orientation.

null

['Yuan, Mengqi', 'Bourerll, David']

2021-10-07T15:47:13Z

8/16/13

Mechanical Engineering

null

['https://hdl.handle.net/2152/88486', 'http://dx.doi.org/10.26153/tsw/15420']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['nitrogen flow', 'Laser Sintering', 'part bed surface temperature']

Nitrogen Flow Effects on Part Bed Surface Temperature during Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4ca23f1d-1030-4a1a-96d5-d7d4697db441/download

University of Texas at Austin

The role of nitrogen flow rate was invested as it affects the surface temperature of a polymer laser sintering part bin. A SinterStation 2500® was used for this study. The effect of nitrogen chamber flow rates between 0.5 and 2.5 m3/hr was observed and compared to the results of a computational fluids dynamics model. Increasing convective flow generates a uniform reduction in the surface temperature, but it does not meaningfully reduce surface temperature gradients. The part bin piston was modified to allow down drafting of nitrogen through the part bin. Down drafting, while once considered to be effective in accelerating cooling at the end of builds, did not have a significant effect on the surface temperature profile.

null

['Dietrich, Stefan', 'Englert, Lukas', 'Pinter, Pascal']

2021-11-09T15:19:29Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90091', 'http://dx.doi.org/10.26153/tsw/17012']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['porosity analysis', 'x-ray computed tomography', 'laser powder bed fusion', 'metal FFF']

Non-Destructive Characterization of Additively Manufactured Components Using X-Ray Micro-Computed Tomography

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7a7e5112-1f97-4c1f-b4bd-373b2c0b0b8c/download

University of Texas at Austin

Quality control and microstructure characterization are essential corner stones of the process optimization through the understanding of process-microstructure-relations in additive manufacturing. The scope of this work is to investigate the relationships between porosity and the process parameters as well as component geometry based on X-ray micro-computed tomography data and thus improving the ability for improved process control. Using test geometries manufactured via laser beam manufacturing and metal fused filament fabrication in combination with specialized image analysis and data fusion algorithms an extensive analysis of pore morphology, position and orientation with respect to the printing path could be carried out. The results show a clear connection between printing strategies as well as part geometry and allow for a direct connection to mechanical performance characteristics determined by the pore architecture like for example fatigue and failure behavior.

null

['Albakri, Mohammed', 'Sturm, Logan', 'Williams, Christopher B.', 'Tarazaga, Pablo']

2021-10-21T19:42:10Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89432

eng

2015 International Solid Freeform Fabrication Symposium

Open

['impedance-based monitoring', 'part abnormalities', 'additive manufacturing', 'quality control']

Non-Destructive Evaluation of Additively Manufactured Parts via Impedance-Based Monitoring

Conference paper

https://repositories.lib.utexas.edu//bitstreams/58deae40-a995-4137-a483-668276cf6580/download

University of Texas at Austin

The ability of Additive Manufacturing (AM) processes to fabricate complex geometries is somewhat hindered by an inability to effectively validate the quality of printed complex parts. Furthermore, there are classes of part defects that are unique to AM that cannot be efficiently measured with standard Quality Control (QC) techniques (e.g., internal porosity). Current QC methods for AM are limited to either destructive evaluation of printed test coupons, or expensive radiation-based scanners of printed parts for non-destructive evaluation. In this paper, the authors describe their use of impedance-based structural monitoring to indirectly measure printed part abnormalities. By bonding a piezoceramic (PZT) sensor to a printed part, the measured electrical impedance of the PZT can be directly linked to the mechanical impedance of the part. By observing deviations in the mechanical impedance of the part, as determined by this quick, non-intrusive electrical measurement, one is able to detect the existence of part defects. In this paper, the authors explore the effectiveness and sensitivity of the technique as a means for detecting of a variety of defect types and magnitudes.

null

['Nomoto, Sukeharu', 'Segawa, Masahito', 'Wakameda, Hiroshi']

2021-11-15T20:58:39Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90269', 'http://dx.doi.org/10.26153/tsw/17190']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['multi-phase field method', 'non-equilibrium', 'thermodynamics', 'machine learning', 'stainless steel', 'solidification', 'additive manufacturing']

Non-Equilibrium Phase Field Model Using Thermodynamics Data Estimated by Machine Learning for Additive Manufacturing Solidification

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9935fac7-2574-497a-a858-6cc43e24651b/download

University of Texas at Austin

A multi-phase field method using finite interface dissipation model proposed by Steinbach et al. is applied to simulate solidification microstructure evolution of stainless steel composition in the non-equilibrium condition of high cooling rate and temperature gradient of additive manufacturing. The calculation is performed for quinary system in order to simulate solidification of engineering composition. Thermodynamic calculation using CALPHAD database in this multi-phase field method calculation is replaced by machine learning prediction procedure to reduce calculation time. The microstructure evaluated by using machine learning parameter is good agreement with one directly coupled with CALPHAD database. This calculation is approximately five times faster than the direct CALPHAD calculation method. Finally, it is confirmed that this multi-phase field method can be applicable to simulate non-equilibrium phase transformation of additive manufacturing condition with high numerical stabilization.

null

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

2020-02-21T15:22:35Z

8/3/05

Mechanical Engineering

null

['https://hdl.handle.net/2152/80061', 'http://dx.doi.org/10.26153/tsw/7083']

eng

2005 International Solid Freeform Fabrication Symposium

Open

powder materials

Non-isothermal Initial Stage Sintering Strain Model with Application to 316L Stainless Steel

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b05baddc-e3ba-4d21-a934-406ad7ff6630/download

null

['Hoglund, Robert', 'Smith, Douglas E.']

2021-10-21T15:01:53Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89387

eng

2015 International Solid Freeform Fabrication Symposium

Open

['Fused Deposition Modeling', 'topology optimization', 'material distribution']

Non-Isotropic Material Distribution Topology Optimization for Fused Deposition Modeling Products

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ef78ac66-bf37-42c9-91d4-497aaa849241/download

University of Texas at Austin

Mechanical properties of products produced with the Fused Deposition Modeling (FDM) process are known to be dependent on bead direction, especially when short fiber reinforcement is added to the polymer filament feedstock. As a result, the structural performance of fiber-filled FDM parts is expected to be improved by simultaneously computing preferred deposition directions while optimizing the internal support structure. This paper presents a topology optimization method for computing the material distribution within a fiber-reinforced polymer composite FDM part that incorporates the non-isotropic mechanical properties of the bead structure. Unlike the well-established homogenization topology optimization method which determines pointwise orthotropic properties by increasing the complexity of the design problem, our approach takes advantage of the simplicity of the SIMP method where the underlying orthotropic orientation is assumed. Computed results show the effect that the orientation of fiber filled bead orthotropic microstructure has on part topology for 2D FDM parts.

null

['Sharma, Maharshi A.', 'Patterson, Albert E.']

2024-03-26T20:30:11Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124397', 'https://doi.org/10.26153/tsw/51005']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['FFF process', 'extrusion-based additive manufacturing', 'control systems', 'dynamic modeling']

Non-Linear Dynamic Modeling of Cartesian-Frame FFF 3-D Printer Gantry for Predictive Control

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e4625159-dac0-4e70-aaa5-458bc219d6dc/download

University of Texas at Austin

This paper presents the development of a dynamic model of an FFF 3-D printer gantry (2-D) that is useful for developing an open-loop predictive control system. This predictive control system based on the mechanics of the system will help to reduce manufacturing defects by minimizing position error in the printing head. A six-dimensional non-linear dynamic model of the printer gantry was derived using Newton-Euler method, followed by a Lagrangian dynamic model to gain additional insight on energy transfer aspects and model validation. A state-space model of the full system was developed for positioning and control. A detailed case-study of an example printer was completed in MATLAB-Simulink to demonstrate the system model with comparisons from the analytical model and physical characterization on a real printer. Finally, a few examples of passive control designs were illustrated for predictive control development. It was concluded that dynamics-based predictive control is a promising, realistic, and practical approach to controlling the dynamic error and dimensional error commonly seen with FFF machines.

null

Chen, Yong

2020-03-09T14:25:05Z

8/21/07

Mechanical Engineering

null

['https://hdl.handle.net/2152/80184', 'http://dx.doi.org/10.26153/tsw/7203']

eng

2007 International Solid Freeform Fabrication Symposium

Open

Stereolithography

Non-Uniform Offsetting and its Applications in Laser Path Planning of Sterolithography Machine

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7861f3c4-a9cb-4e63-b910-14c400f60277/download

null

Laser path planning is an important step in solid freeform fabrication processes such as Stereolithography (SLA). An important consideration in the laser path planning is to compensate the shape of laser beam. Currently the compensation is divided into two steps, Z-compensation and X-Y compensation, and the shape of laser beam is assumed to be uniform for the whole platform. In this research, we present a sampling based non-uniform offsetting method which accounts for the different shapes of laser beam at various locations. We discuss the related steps and algorithms. We demonstrate its effectiveness by using various test cases. Besides improving the accuracy of SLA machine, non-uniform offsetting can also be applied to address other accuracy issues caused by thermal and structural variations

null

['du Plessis, Anton', 'Yadroitsava, Ina', 'Yadritsev, Igor']

2021-11-09T15:15:41Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90090', 'http://dx.doi.org/10.26153/tsw/17011']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['micro computed tomography', 'microCT', 'bottlenecks', 'additive parts', 'additive manufacturing']

Nondestructive Micro-CT Inspection of Additive Parts: How to Beat the Bottlenecks

Conference paper

https://repositories.lib.utexas.edu//bitstreams/81203d6d-c4fc-40fd-a8ea-a8f5e3ea357c/download

University of Texas at Austin

Micro computed tomography (microCT) is widely in use for the inspection of additively manufactured parts. The main use of the technique is to detect unwanted voids inside the part. However, the ability to detect these kind of defects is strongly affected by image quality, which is often directly related to the scan time. Selecting fast scan settings (e.g. 5 minutes per part) can work for many situations where major flaws need to be identified (such as large unmelted cavities), but this may result in the missing of critical defects which are smaller, such as clustered metallurgical pores or chains of fine voids between layers or tracks caused lack of fusion . An important defect type which can be missed by fast scanning is small inclusions also. Possible ways of overcoming this problem are discussed. After scanning, image analysis requires computing power, time and skilled human interface for proper analysis. Reduction of the image analysis workflow is possible using semi-automated analyses and the data size can be reduced using simple methods, including removal of unwanted data outside the object, 8-bit data size and even .STL format outputs in some cases. In this paper all the above is discussed in relation to reducing the bottlenecks (problems causing delays in getting results and slowing the workflow) often associated with microCT.

null

['Simeunovic, A.', 'Hoelzle, D.']

2021-11-15T21:15:48Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90275', 'http://dx.doi.org/10.26153/tsw/17196']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['nonlinear model', 'linearized model', 'gray box model', 'direct-write printing', 'extrusion-based additive manufacturing']

Nonlinear and Linearized Gray Box Models of Direct-Write Printing Dynamics

Conference paper

https://repositories.lib.utexas.edu//bitstreams/928d2bf1-2c6e-477b-8c25-8819d1bc3abc/download

University of Texas at Austin

Control of material metering in material extrusion based additive manufacturing modalities, such as positive displacement direct-write, is critical for manufacturing accuracy. However, in positive displacement direct-write, transient flows are poorly controlled due to capacitive pressure dynamics - pressure is stored and slowly released over time from the build material and other compliant system elements, negatively impacting flow rate startups and stops. Thus far, modeling of these dynamics has ranged from simplistic, potentially omitting key contributors to the observed phenomena, to highly complex, making usage in control schemes difficult. Here, we present nonlinear and linearized models that seek to both capture the capacitive and nonlinear resistive fluid elements of positive displacement direct-write systems and to pose them as ordinary differential equations for integration into nonlinear and linear control schemes. We validate our theoretical work with experimental flow rate and material measurements across a range of extrusion nozzles and materials to address different feature sizes and diverse applications spanning tissue engineering, electronics fabrication, and food science. As part of this experimental work, we explore the contribution of the bulk system compliance and the build material compliance to these dynamics. We show that all models accurately describe the measured dynamics, facilitating ease of integration into future nonlinear and linear control systems. Additionally, we show that while build material compliance may be nearly entirely reduced through appropriate system design, the compliance from build material alone is significant enough to require feedback control to fully control material delivery.

null

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

2021-11-18T02:08:06Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90408', 'http://dx.doi.org/10.26153/tsw/17329']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['NMPC', 'switching systems', 'UV curing', 'additive manufacturing', 'optimal time control']

Nonlinear Model Predictive Control of UV-Induced Thick Composite Manufacturing Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3f04c4a1-74b2-4f21-9904-c632a9b795ee/download

University of Texas at Austin

In this paper the nonlinear model predictive control (NMPC) of UV-induced curing of composite material for manufacturing of thick parts is proposed. The process involves layer-by-layer curing of thin composite laminates to form thick part. The model for NMPC switches when a new layer is added to the existing layer. The layer addition times are determined externally. The offline optimal control is used to determine the optimal time and temperature profile which will give uniform cure distribution of a thick composite material. Once the temperature trajectory and optimal time sequences are found, the NMPC is implemented for online control. The objective is to determine theoretical optimal behavior (assuming the process measurement is available) which will be used for online switching NMPC for tracking the reference temperature.

null

['Brown, R.', 'Morgan, C.T.', 'Majewski, C.E.']

2021-11-11T15:38:38Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90223', 'http://dx.doi.org/10.26153/tsw/17144']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['elastomeric material', 'characterization', 'testing', 'high speed sintering', 'HSS']

Not Just Nylon... Improving the Range of Materials for High Speed Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a9a38f02-ac38-4b34-bfe4-5b9e381714c7/download

University of Texas at Austin

High Speed Sintering (HSS) is an emerging, recently commercialised Additive Manufacturing (AM) process which uses an infrared absorbing ink and infrared lamp to selectively sinter layers of polymer powder. Currently, Nylon 12 and its composites are used as the default feedstock due to their large processing windows. However, to meet the increasing variety of end use applications afforded by the benefits of AM, a wider range of materials must be developed. This work presents the characterisation and testing of a new elastomeric material for use in HSS. Parts were produced over a range of processing conditions, varying key parameters such as part bed temperature, ink density and lamp speed. Performance indicators including powder recovery, surface roughness and tensile data were evaluated over the range of conditions tested and all indicated the material’s suitability for use as an HSS material.

null

['Schmidt, J.', 'Sachs, M.', 'Fanselow, S.', 'Wirth, K.-E.', 'Peukert, W.']

2021-10-27T22:11:26Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89630

eng

2016 International Solid Freeform Fabrication Symposium

Open

['selective laser beam melting', 'polymer powders', 'stirred media milling', 'rounding']

Novel Approaches for the Production of Polymer Powders for Selective Laser Beam Melting of Polymers

Conference paper

https://repositories.lib.utexas.edu//bitstreams/78b069a3-b39b-4765-a494-3f183b78eac9/download

University of Texas at Austin

The opening of new fields of application of powder-based additive manufacturing methods like selective laser beam melting of polymers currently is hindered by the limited availability of materials showing good processability. So far, virtually only polyamides are available as optimized powder materials. Two innovative methods for production of spherical polymer micro particles for selective laser melting are discussed: The first approach, stirred media milling and rounding, is applicable for a variety of polymers. It will be exemplarily discussed for polyesters and the dependency of product properties (particle size distribution, shape, crystallinity) on the process parameters in the comminution and in the rounding step will be assessed. The second method, melt emulsification, will be demonstrated for polypropylene. Moreover, the possibilities of dry coating to tailor particle properties are illustrated. The influence of powder properties on the processability and on the quality of the obtained devices is outlined.

null

['Bandyopadhyay, Amit', 'Atisivan, Raj', 'Bose, Susmita']

2019-03-15T16:10:05Z

1999

Mechanical Engineering

null

['https://hdl.handle.net/2152/73686', 'http://dx.doi.org/10.26153/tsw/828']

eng

1999 International Solid Freeform Fabrication Symposium

Open

['Ceramic materials', 'high strength']

Novel Ceramics and Metal-Ceramic Composites via Fused Deposition Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7c860bc1-c6f3-4f81-a592-3721df5096dc/download

null

Indirect fused·· deposition process is utilized.·.. to ·fabricate controlled porosity ceramic structures using alumina, mullite, zirconia, LSCF-perovskite, tricalcium phosphate and hydroxyapatite, where pore size, pore shape and pore connectivity are varied from one end to the other end of the parts. Some of these porous ceramics are then infiltrated with metals via pressureless reactive metal infiltration to form novel metal-ceramic composites. Thispaper will describe processing, structures of various porous and metal-infiltrated composites and their physical and mechanical properties.

null

['Hutton, Logan J.', 'Bartolai, Joseph']

2024-03-26T20:04:21Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124385', 'https://doi.org/10.26153/tsw/50993']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['material extrusion', 'infill region', 'additive manufacturing']

Novel Concepts to Integrate Dense and Sparse Infill Regions in Material Extrusion AM Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b7e146ac-d0b4-4c4a-a7e2-e3ccaeb2ee55/download

University of Texas at Austin

Modern toolpath generation softwares, or “slicers," allow for multiple regions within a Material Extrusion Additive Manufacturing produced part to be assigned different processing parameters, including infill density. Contemporary slicers develop these different infill regions independently, leading to discontinuities in the toolpaths at the region's boundaries. This work investigates the effect these discontinuities have on part strength, and tests a variety of novel approaches to connect infill regions in a continuous manner to improve part properties. Mechanical properties of parts built by toolpaths generated using Ultimaker Cura and Slic3r are compared to those of parts built using the novel build strategies presented in this work. The continuous and sequential novel build strategies presented in this work show statistically significant mechanical property increases.

null

['Ghazanfari, Amir', 'Li, Wenbin', 'Leu, Ming C.', 'Hilmas, Gregory E.']

2021-10-28T20:22:34Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89690

eng

2016 International Solid Freeform Fabrication Symposium

Open

['3D printing', 'extrusion freeforming', 'fused deposition', 'robocasting', 'radiation drying']

A Novel Extrusion-Based Additive Manufacturing Process for Ceramic Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0a02b858-4dd8-4d57-8fff-616c6e4c1595/download

University of Texas at Austin

An extrusion-based additive manufacturing process, called the Ceramic On-Demand Extrusion (CODE) process, for producing three-dimensional ceramic components with near theoretical density is introduced in this paper. In this process, an aqueous paste of ceramic particles with a very low binder content (<1 vol%) is extruded through a moving nozzle at room temperature. After a layer is deposited, it is surrounded by oil (to a level just below the top surface of most recent layer) to preclude non-uniform evaporation from the sides. Infrared radiation is then used to partially, and uniformly, dry the just-deposited layer so that the yield stress of the paste increases and the part maintains its shape. The same procedure is repeated for every layer until part fabrication is completed. Several sample parts for various applications were produced using this process and their properties were obtained. The results indicate that the proposed method enables fabrication of large, dense ceramic parts with complex geometries.

null

['Graff, K.F.', 'Short, M.', 'Norfolk, M.']

2021-09-29T22:47:40Z

9/23/10

Mechanical Engineering

null

['https://hdl.handle.net/2152/88224', 'http://dx.doi.org/10.26153/tsw/15165']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['ultrasonic additive manufacturing', 'Very High Power Ultrasonic Additive Manufacturing System', 'ultrasonic power', 'EWI', 'Solidica™']

Very High Power Ultrasonic Additive Manufacturing (VHP UAM) for Advanced Materials

Conference paper

https://repositories.lib.utexas.edu//bitstreams/91056bef-026a-47ce-8626-cf6a2986f5d7/download

University of Texas at Austin

To extend current ultrasonic additive manufacturing (UAM) to advanced materials, higher speeds and larger parts, it was essential to greatly increase the process ultrasonic power. EWI, with Solidica™, several industry, agency and academic partners, and support of Ohio’s Wright Program, have developed a “Very High Power Ultrasonic Additive Manufacturing System” that greatly extends current technology. A key part was the design of a 9.0 kW “push-pull” ultrasonic system able to produce sound welds in materials such as Ti 6-4, 316SS, 1100 Cu and Al7075. The VHP system can fabricate parts of up to 1.5m x 1.5m x 0.6m, with process and software developments that enable forming contoured surfaces.

null

['Santangelo, Michael', 'Silwal, Bishal', 'Purdy, Alexander']

2021-10-28T20:31:35Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89693

eng

2016 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'wire feed', 'hot-wire GTAW', 'ABAM']

Vibration Assisted Robotic Hot-Wire Gas Tungsten Arc Welding (GTAW) for Additive Manufacturing of Large Metallic Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4624afa2-3590-442c-8215-9f5853f3ee40/download

University of Texas at Austin

Most of the metal additive manufacturing technologies are focused on high cost and high end applications. There is in need, a low cost additive manufacturing technology suitable for low and high end metallic applications. Robotic automated welding can be considered as an alternative to manufactured large scale metal parts with layer by layer approach. However, many obstacles have to be overcome to make it viable technology in additive manufacturing industry. A Robotic hot-wire Gas Tungsten Arc Welding (GTAW) with low frequency vibrating filler wire has been used to deposit a metallic alloy. Different trials of weld-on-bead experiments were performed to obtain the desired envelop of the melt pool shape for build parts with low manufacturing costs and low build times.

null

['Kandukuri, Shruthika', 'Kashyap, Atharva', 'Lipton, Jeffrey']

2023-02-17T14:32:44Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117483', 'http://dx.doi.org/10.26153/tsw/44364']

eng

2022 International Solid Freeform Fabrication Symposium

Open

sander grips

Vibration Reduction Using Material Jetted Parts for Sander Grips

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3def33ee-5787-44d0-90eb-c9cfb0241c72/download

null

Workers in many industries are exposed to harmful vibrations that negatively impact their comfort and long-term health through tools such as hand-held sanders. Here we show that using material jetting we can produce durable and effective vibration protection equipment that reduces vibrations felt by the user by an average of 23% to 45%. We developed 3D printed vibration absorbing grips made from a blend of TangoBlack+ and uncured liquid. The grips were deployed at a Boeing factory and survived 1 month of usage. The grips were best at absorbing higher- frequency vibrations, able to reduce frequencies above 1kHz by over 20dB. Our results demonstrate promising capabilities of material jetting viscoelastic materials for direct part production of ergonomic components. Moreover, these grips could be improved and used to dampen vibrations on other tools such as bucking bars and used in various other industries.

null

['Greeley, Andrew', 'Cormier, Denis']

2021-12-07T18:26:45Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90749', 'http://dx.doi.org/10.26153/tsw/17668']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['directed energy deposition', 'capture effiiciency']

Vibration-Actuated Powder Dispensing for Directed Energy Deposition Systems

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3973d8e1-2bb5-40ab-96f9-6c37d54fafa6/download

University of Texas at Austin

Users of powder-fed directed energy deposition system often face several challenges associated with conventional powder delivery sub-systems. In addition to the high cost of wasted powder, it can be difficult to plan for the amount of material being deposited when some of the dispensed powder is not captured in the melt pool. This work studies the effectiveness of a vibration-actuated powder dispensing system using a nozzle with a small capillary opening. The opening is sized so that particle contact forces arrest powder flow when the vibration actuator is turned off. The relative effects of vibration frequency, vibration acceleration, nozzle size and nozzle inclination are compared with the goal of having the output mass flow rate monotonically change with one of these parameters. For the materials and parameters explored in this study, nozzle inclination is found to have the largest effect on mass flow rate output and has the desired monotonically changing relationship.

null

Spencer, John D.

2018-05-03T16:27:48Z

1993

Mechanical Engineering

doi:10.15781/T2DJ5906T

http://hdl.handle.net/2152/65034

eng

1993 International Solid Freeform Fabrication Symposium

Open

['rapid prototyping', 'Department of Manufacturing Engineering and Operations Management', 'stereolithography']

Vibratory Finishing of Stereolithography Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/dfee2f29-d292-4447-a6c4-e20488c13e34/download

null

Rapid Prototype polymer resin models produced by Stereolithography have, by the nature of the process, a relatively poor surface roughness, particularly on concave and convex surfaces. In many cases this is unacceptable, and slow and tedious manual finishing techniques are often used to improve the surface. An investigation has been conducted into a range of automated finishing techniques with the aim of producing an acceptable surface roughness. This paper presents the results from two techniques, Vibratory Bowl Abrasion and Ultrasonic Abrasion using components made from Ciba-Geigy XB5081-1 and XB 5143 resins. Initial results from Scanning Electron Microscopy and surface topography analyses suggest that both techniques are capable of improving the model surfaces.

null

['Melvin III, Lawrence S.', 'Das, Suman', 'Beaman Jr., Joseph Jr.']

2018-09-26T19:21:21Z

1994

Mechanical Engineering

doi:10.15781/T29P2WR3K

http://hdl.handle.net/2152/68587

eng

1994 International Solid Freeform Fabrication Symposium

Open

['Video microscopy', 'selective laser sintering', 'Optical mangification']

Video Microscopy of Selective Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a08b6c48-8c45-427f-9980-7b75a59cef14/download

null

This paper presents the design and implementation of a video microscopy system that enables real time observation and archival of selective laser sintering of polymer and metal materials. The design objectives and selection of system components are discussed in the first section of this paper. Experimental results from preliminary experiments conducted on polycarbonate, wax and nylon powders are also presented.

null

['Choi, S.H.', 'Cai, Y.']

2021-09-30T14:28:13Z

9/23/10

Mechanical Engineering

null

['https://hdl.handle.net/2152/88256', 'http://dx.doi.org/10.26153/tsw/15197']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['dual-level reconfigurable additive manufacturing system (DRAMS)', 'digital fabrication', 'process performance', 'system configurations']

A Virtual Dual-Level Reconfigurable Additive Manufacturing System for Digital Object Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/76e437a4-2f3a-42aa-a560-b6092ba7089b/download

University of Texas at Austin

This paper proposes a virtual dual-level reconfigurable additive manufacturing system (DRAMS) for simulation and verification of deposition strategies in digital fabrication of product prototypes. The DRAMS is aimed to improve additive manufacturing (AM) processes with the concept of system reconfiguration. It consists of adaptable support and manipulation modules for deposition of fabrication materials. Topologies are investigated to determine the structures of these modules, and methods are developed to evaluate and optimize the system configuration. Simulations show that the DRAMS can not only handle prototypes of different sizes and fabrication materials, but also increase the process speed. The DRAMS offers an effective tool for simulation, verification and optimization of deposition strategies under different system configurations to improve process performance.

null

['Gibson, I.', 'Cobb, S.', 'Eastgate, R.']

2018-05-03T17:45:45Z

1993

Mechanical Engineering

doi:10.15781/T2QV3CM8T

http://hdl.handle.net/2152/65047

eng

1993 International Solid Freeform Fabrication Symposium

Open

['Department of Manufacturing Engineering and Operations Management', 'Virtual Reality', '3D CAD systems', 'rapid prototyping']

Virtual Reality and Rapid Prototyping: Conflicting or Complimentary?

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7bb68886-65fd-4650-9fa5-135001b04a85/download

null

It is likely that the uses for virtual reality (VR) will coincide with applications that rapid prototyping systems have already been used for. VR, with the ability to model real life environments, presents an ideal base for the design and development of new manufactured products. As a method of producing physical models directly from 3D CAD systems, rapid prototyping technology has also been used to visualise new product designs. This paper attempts to determine whether the two technologies are a means to the same end or whether they combine to form a more efficient route to product development.

null

['Qiu, Dan', 'Langrana, Noshir A.', 'Danforth, Stephen C.', 'Safar, Ahmad', 'Jafar, Mohsen']

2019-03-01T17:29:27Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73514', 'http://dx.doi.org/10.26153/tsw/664']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['CAD', 'LM']

Virtual Simulation for Multi-material LM Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/55891e1e-3100-43f6-8b5b-aadd87201b29/download

null

In an ONR funded MURI program, to improve quality of multi-material parts, we've been developing an advanced computer simulation for the multi-material layered manufacturing (LM) process. The CAD models and their .stLfiles are created using. the commercially available software such as I-DEAS and ProE. Using this information, one tool path file per material is generated. Our file preparation algorithm, systematically, layer by layer, integrates all tool path files into one multi-material tool path file. The results of the multi-material tool path are graphically visualized using the simulation algorithm (written in c++ & SGI OpenGL). From a virtual simulation, we can check the LM process, and make the best selection of tool path parameters afterwards. After several trials from design to simulation, if the simulation result is acceptable, the real manufacturing can be started. And the part's quality should be better than a part manufactured without running simulation in advance. This paper will represent .•. new studies on using real toadshapes to get more realistic simulation results. Many parts have been successfully simulated using our method.

null

['Duty, Chad', 'Ajinjeru, Christine', 'Kishore, Vidya', 'Compton, Brett', 'Hmeidat, Nadim', 'Chen, Xun', 'Liu, Peng', 'Hassen, Ahmed Arabi', 'Lindahl, John', 'Kunc, Vlastimil']

2021-11-02T18:14:11Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89854

eng

2017 International Solid Freeform Fabrication Symposium

Open

['viscoelastic model', 'print conditions', 'printability', 'extrusion-based printing']

A Viscoelastic Model for Evaluation Extrusion-Based Print Conditions

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4e02ec81-20bd-4584-856c-cefafbb69910/download

University of Texas at Austin

Extrusion-based printing systems have improved significantly over the past several years, allowing for higher throughput, higher temperatures, and larger components. At the same time, advanced materials are being introduced on the market that can provide improved performance over a range of operating conditions. Often these materials incorporate fiber reinforcements, reactive resins, and additives to control reaction kinetics, flow rheology, or thermal stability. This study presents a general framework for evaluating the printability of various candidate materials based on a basic viscoelastic model. The model addresses fundamental requirements for extrusion-based printing, including pressure-driven flow, bead formation, bead functionality, and component-level functionality. The effectiveness of this model for evaluating the impact of compositional variations and identifying appropriate processing conditions has been demonstrated for specific materials on direct write, fused filament fabrication, and large-scale extrusion platforms.

null

['Vaish, Apoorv', 'Yang Lee, Shien', 'Valdivia Alvarado, Pablo']

2021-11-09T15:38:53Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90098', 'http://dx.doi.org/10.26153/tsw/17019']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['viscosity control', 'pseudoplastic polymers', 'embedded 3D-printing', 'direct ink writing']

Viscosity Control of Pseudoplastic Polymer Mixtures for Applications in Additive-Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/75c321e5-6461-4dec-9ded-11fc6f235dda/download

University of Texas at Austin

Various additive manufacturing (AM) processes exploit the rheological properties of non-Newtonian (e.g. pseudoplastic) polymers for stability and feature realization. For embedded 3D-printing (e3DP) and direct ink writing (DIW), features are deposited on top or within a layer of matrix/base material and the rheological properties of the matrix are crucial for satisfactory prints. Due to their high apparent viscosities under static conditions, these base polymers do not flow easily when poured in bulk into the fabrication space. Traditionally, manual methods were employed to spread them into an even layer. In this study, an alternative approach to spread and level pseudoplastic polymers using oscillatory shear stresses generated by a vibrating actuator is presented. The proposed approach lowers the viscosity of the polymers, thereby facilitating gravity-driven flow to generate a flat polymer-air interface. A fluid rheology model detailing the parameters influencing the process is presented and experiments are performed using these parameters.

null

['Karnati, Sreekar', 'Matta, Niroop', 'Sparks, Todd', 'Liou, Frank']

2021-10-07T15:33:00Z

2013

Mechanical Engineering

null

['https://hdl.handle.net/2152/88482', 'http://dx.doi.org/10.26153/tsw/15416']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['laser metal deposition', 'process monitoring', 'thermal camera']

Vision-based Process Monitoring for Laser Metal Deposition Processes

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0489e5e2-3441-4eda-9170-8c62cd4b05bb/download

University of Texas at Austin

Laser Metal deposition is a process with immense scope and promise for becoming a robust manufacturing technology in the near future. Monitoring process variables is very instrumental in process planning and output monitoring. The current work deals with realizing the effect of power modulation on size of the high temperature region during deposition with varying powder feed. A thermal camera was used to visualize and analyze the deposition process. The area of the high temperature region through the deposition was identified and compared to realize the effect of each variable parameter during deposition. The power modulation was fruitful in modulating the area of the high temperature zone. Optimum set of parameters to perform deposition were identified.

null

['Adediran, A.I.', 'Nycz, A.', 'Thornton, A.', 'Love, L.J.']

2021-11-04T18:52:19Z

2017

Mechanical Engineering

null

['https://hdl.handle.net/2152/90003', 'http://dx.doi.org/10.26153/16924']

eng

2017 International Solid Freeform Fabrication Symposium

Open

['laser metal wire deposition', 'LMD-w', 'image processing', 'visual sensing', 'discontinuities', 'error detection']

Visual Sensing and Image Processing for Error Detection in Laser Metal Wire Deposition

Conference paper

https://repositories.lib.utexas.edu//bitstreams/76be9105-9e5c-41f7-8440-340220e95ba3/download

University of Texas at Austin

Laser metal deposition with wire (LMD-w) involves feeding metal wire through a nozzle and melting the wire with a high-power laser. With efficient process control, i.e. sensing, processing, and feedback correction of errors, the technology has the potential to change the course of manufacturing. However, the limitation most often encountered in LMD is the difficulty in controlling the process. Monitoring and control of metal additive manufacturing processes has been mostly researched on powder-based systems and has not been extensively investigated on metal wire feed systems. This work proposes a method for detecting discontinuities in a deposited layer in the LMD-w process via optical inspection and processing of images obtained from a high-resolution camera. The aim is to develop an effective sensing module that automatically detects irregularities in each layer before proceeding to subsequent layers, which will reduce part porosity and improve inter-layer bond integrity.

null

['Kattethota, Gautham', 'Henderson, Mark']

2019-02-22T19:53:22Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73466', 'http://dx.doi.org/10.26153/tsw/616']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['FDM', 'Rapid Prototyping']

A Visual Tool to Improve Layered Manufacturing Part Quality

Conference paper

https://repositories.lib.utexas.edu//bitstreams/19159cc2-889f-40de-83c0-726c36372b32/download

null

A software tool is described that will aid the user in. choosing the optimum build orientation to obtain the ..best composite set of surface finishes on a part built .on a Fused Deposition Modeling (FDM) rapid prototyping machine.• Experiments were conducted to obtain statistical .surface roughness values as a function of orientation and layer thickness.Three types of surfaces (features}.have been. considered planar (both upward facing and downward facing (over hang surfaces)),.quadratic and free form Surfaces..Data analysis of surface roughness of planar surfaces at various orientations·and their mapping. to. quadratic and freeform surfaces are presented. decision support software tool allows dynamic .. color-coded visualization of the surface quality simultaneous with build parameters including orientation and layer thickness.

null

['Choi, S.H.', 'Chan, A.M.M.']

2019-10-24T18:06:24Z

2002

Mechanical Engineering

null

['https://hdl.handle.net/2152/77413', 'http://dx.doi.org/10.26153/tsw/4502']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Prototyping

Visualization of Surface Accuracy for Virtual Prototyping

Conference paper

https://repositories.lib.utexas.edu//bitstreams/da94f71c-e098-49a4-95df-8dae12baadd3/download

null

This paper introduces a virtual prototyping (VP) system that simulates a RP process to produce a virtual prototype of a product, which facilitates visual study of the surface quality of the physical prototype that the RP machine will subsequently fabricate. The virtual prototype displayed in a computerized virtual environment allows the designer to analyze the surface texture and accuracy of a product prototype conveniently. It may be super-imposed on its original design so that all dimensional deviations are clearly highlighted. The system can further pinpoint the areas in which the dimensional deviations are out of the acceptable range. The designer can hence improve the accuracy of the prototype well before physical fabrication by optimizing the RP fabrication parameters, such as the layer thickness, hatch space and build orientation, in the system. In this paper, the simulation principles will be described and case studies will be given to illustrate how the system works.

The authors would like to acknowledge the Research Grant Council of the Hong Kong SAR Government and the CRCG of the University of Hong Kong for their financial support for this project.

null

['Campbell, R. Ian', 'Jee, Haeseong J.', 'Lee, H.S.']

2019-09-23T16:56:43Z

2000

Mechanical Engineering

null

['https://hdl.handle.net/2152/75970', 'http://dx.doi.org/10.26153/tsw/3069']

eng

2000 International Solid Freeform Fabrication Symposium

Open

Visualization

Visualization Tools for Design Support in SFF 437

Conference paper

https://repositories.lib.utexas.edu//bitstreams/213867fa-8816-4191-8c2b-4b9719851778/download

null

When considering the use of SFF, there are many questions a designer might ask. What model orientation should be used, will the model have adequate aesthetic and functional properties, is the STL file suitable for transfer to the SFF machine? These questions could be answered by a comprehensive design support system for SFF. This paper addresses a number of components for such a system that can be met through the use of visualization tools. These include: 1. Visualization of surface roughness 2. Visualization of characteristic features (e.g. surface macro-texture) 3. Visual simulation of fabrication Example applications of these tools are presented together with a status review of their implementation to date. It is envisaged that these tools will be incorporated into an already existing network-based preprocessor used for visualization, repair and slicing of STL files. The direction of future work is also discussed which will include the visual representation of functionally graded materials (connected with FEM results).

null

['Pegues, Jonathan', 'Roach, Michael', 'Williamson, R. Scott', 'Shamsaei, Nima']

2021-11-11T15:08:09Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90213', 'http://dx.doi.org/10.26153/tsw/17134']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'fatigue behavior', 'defects', 'fractography']

Volume Effects on the Fatigue Behavior of Additively Manufactured Ti-6Al-4V Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/df161b01-b19f-415f-80e0-b01fc1e03ddf/download

University of Texas at Austin

Recent interest to implement additive manufactured parts into structural applications has created a critical need to better understand the fatigue behavior of these parts. Alloys such as Ti-6Al-4V are popular in the aerospace and biomedical industries due to their superior strength to weight ratio and biocompatibility. In these two industries, part sizes can range from very small surgical implants to large structural components, all of which are subjected to cyclic loading conditions. The fatigue behavior of additively manufactured parts may show more sensitivity to part size than their wrought counterparts due to the defects that are inherent to the fabrication process. This research investigates the sensitivity of additively manufactured Ti-6Al-4V parts to volume size by comparing the stress-life fatigue curves of three geometries with increasing gage volumes. Results indicate that additive Ti-6Al-4V parts show reduced fatigue lives because of an increase in surface or near-surface defects.

null

['Ma, Di', 'Lin, Feng', 'Chua, Chee Kai']

2019-03-08T17:50:40Z

1999

Mechanical Engineering

null

['https://hdl.handle.net/2152/73574', 'http://dx.doi.org/10.26153/tsw/716']

eng

1999 International Solid Freeform Fabrication Symposium

Open

['Rapid prototyping', 'Solid Freeform Fabrication']

Volume Modeling for Rapid Prototyping

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ea247511-1425-41e7-abfd-b77b4fc20247/download

null

The expanding workspace of Rapid Prototyping will draw on the new developments in geometric modeling. Volume modeling has substantial advantages over other modeling schemes to meet the emerging requirements of Rapid Prototyping technology. It provides us with a new approach to design complex geometry and topology. The integration of the volume modeling and Rapid Prototyping technology will help us to fully exploit RP's ability to fabricate objects with complex structures. This paper addresses our research and practice in a volume modeling system toward Rapid Prototyping. Novel techniques in volumetric data manipulation, NURBS volume models and triangular facet generation over solid models are presented. Computer models designed by this system and their corresponding DTM products are also shown atthe end of this paper.

null

['Yim, Soonkyu', 'Gea, Hae Chang']

2019-10-18T16:04:01Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76246', 'http://dx.doi.org/10.26153/tsw/3335']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Voxel-based

Voxel-based Modeling with Multi-resolution Wavelet Transform for Layered Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3857a0d5-4939-429c-8623-a8a36be079ef/download

null

A voxel-based modeling system with multi-resolution for layered manufacturing is presented in this paper. When dealing with discretized data input, voxel-based modeling shows its clear advantages over the conventional geometric modeling methods. To increase the efficiency of voxel data due to its large storage space requirement, multi-resolution method with wavelet transform technique is implemented. Combining with iso-surface generation and lossless polygon reduction, this voxel-based modeling method can easily work with layered manufacturing. To demonstrate these concepts, components with different resolutions are built using Layered Manufacturing and presented in the paper.

null

['Ye, Jennings Z.', 'Sun, Yaxuan', 'Taylor, Hayden']

2024-03-26T20:25:16Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124395', 'https://doi.org/10.26153/tsw/51003']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['computed axial lithography', 'surface quality', 'radon transform', 'voxel']

VOXEL-FREE RADON TRANSFORM FOR IMPROVING SURFACE QUALITY IN COMPUTED AXIAL LITHOGRAPHY

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3a293a2d-ac07-44e7-bd65-c904362eca48/download

University of Texas at Austin

Computed axial lithography (CAL) is an additive manufacturing process that projects light patterns onto a rotating vial of photosensitive resin to print the desired object through the superposition of light energy. Currently, these projection patterns are generated by voxelizing a target object from an STL or another 3D file format and applying the Radon transform through an iterative optimization process. In this work, a voxel-free method to generate projection sets is proposed. Here, the Radon transform is performed directly on a non-voxelized target object by calculating intersections between incident rays of light and triangles of the original STL surface mesh. Initial simulated results show a more consistent light dose at the surface of the object, indicating improved surface quality and smoothness. Additionally, simulations show a more uniform object interior using the proposed method as well as the potential for improved speed scaling with object size.

null