ccm/sff-papers · Datasets at Hugging Face

['Lee, Yousub', 'Simunovic, Srdjan', 'Gibson, Brian', 'Mhatre, Paritosh', 'Roschli, Alex']

2023-01-26T15:12:33Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117315', 'http://dx.doi.org/10.26153/tsw/44196']

eng

2022 International Solid Freeform Fabrication Symposium

Open

Ti-6Al-4V

Modelling of Microstructure Evolution in Wire-Based Laser Direct Energy Deposition with Ti-6Al-4V

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f8c6b7d5-6e88-4b51-aa6c-3cbd7b75cbcb/download

null

Over the past years, wire-based direct energy deposition (DED) has been transitioning from rapid prototyping to the production of end-use part and mass production. However, a wide market penetration of the DED has not happened yet. The difficulties for wide-scale market adoption to critical structural components are related to the development cost for process optimization and for manufacturing of high-quality parts. For metallic components, the process conditions (e.g., power, speed, tool path) control the material and mechanical properties/performance of the printed part. The thermal history strongly determines the phase fraction, morphology, growth pattern, size of microstructure, and nature of defects. Thus, in this study, we: 1) developed a thermal simulation using finite element method, 2) experimentally measured thermal histories from a U-shaped part with four tool paths of horizontal, vertical, raster, and contour to calibrate and validate the thermal model, and 3) investigated the effect of thermal history on microstructure evolution and quantified the microstructural variation during the printing process.

null

['Ryder, G. J.', 'Berzins, M.', 'Childs, T. H. C']

2018-11-16T16:03:58Z

1996

Mechanical Engineering

doi:10.15781/T2JQ0TF3G

http://hdl.handle.net/2152/70292

eng

1996 International Solid Freeform Fabrication Symposium

Open

['sintering process', 'sintering machines', 'Selective Laser Sintering process']

Modelling Simple Feature Creation in Selective Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ee6fca47-27eb-4ee6-89e1-8da06158fe77/download

null

A two dimensional finite difference thermal sintering model has been created to describe the Selective Laser Sintering process(SLS). It includes thermal property variation with position and temperature, and especially adaptive meshing to refine information in regions of high temperature gradients. It has been used to predict density and temperature in both single and multi layer sintering operations, corresponding to experimental results. This paper will present comparisons of theory and experiment for the SLS of simple geometries such as blocks, steps, and cylinders.

null

['Xue, Samuel S.', 'Barlow, Joel W.']

2018-04-12T18:31:32Z

1991

Mechanical Engineering

doi:10.15781/T22F7K78V

http://hdl.handle.net/2152/64283

eng

1991 International Solid Freeform Fabrication Symposium

Open

['Chemical Engineering Department', 'SLS', 'Maxwell-Eucken Model', 'models']

Models for the Prediction of the Thermal

Conference paper

https://repositories.lib.utexas.edu//bitstreams/234ebc93-cb17-427e-84c8-c58eb8b65529/download

null

Five models and eq\1ationsJorthe.predictic;>nof the tbertnal conduc~"ities of powders in the literature are compared with the data obtainedill the experiments of the authors. Anew modified ntodel for the. correlation of the experimental data is presented. Key words: differential scanning calorimetry, porosity, solid content, specific heat, thermal conductivity.

null

['Liang, Xuan', 'Chen, Qian', 'Cheng, Lin', 'Yang, Qingcheng', 'To, Albert']

2021-11-08T21:52:23Z

2017

Mechanical Engineering

null

['https://hdl.handle.net/2152/90051', 'http://dx.doi.org/10.26153/tsw/16972']

eng

2017 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'inherent strain', 'modified method', 'residual distortion']

A Modified Inherent Strain Method for Fast Prediction of Residual Deformation in Additive Manufacturing of Metal Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c48dff75-ea2f-4cb9-991f-33da1a06fa68/download

University of Texas at Austin

Effective prediction of residual deformation is very important to guarantee the quality of metal parts produced by additive manufacturing (AM). However, analytical or numerical models for the AM process are complicated and time consuming thus far. The conventional inherent strain theory can predict residual distortion of the regular metal welding problem. Typically, it is not applicable to the complicated layer-by-layer laser-sintering depositing process. In this paper, a modified inherent strain method is presented to predict the residual deformation much more efficiently. Calculation of the modified inherent strain is based on small-scale thermomechanical simulation of the AM process. Next, the strain values are assigned to the heat-affected zone as material thermal property and a one-time static mechanical analysis is performed. Residual deformation obtained by the new method and the thermomechanical simulation indicates good accuracy and efficiency of the proposed method.

null

['Hagen, Deborah', 'Chen, Alex', 'Beaman, Joseph J.', 'Kovar, Desiderio']

2021-11-18T01:55:56Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90403', 'http://dx.doi.org/10.26153/tsw/17324']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['selective laser flash sintering', 'moisture', 'yttria-stabilized zirconia', 'ceramics']

Moisture Effects on Selective Laser Flash Sintering of Yttria-Stabilized Zirconia

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b13fce3a-801f-477a-bb1a-f7b9738b5b48/download

University of Texas at Austin

Selective laser flash sintering (SLFS) combines a uniform electric field with a localized, scanning laser as the only external heating source. The presence of a large uniform electric field can greatly increase the sintering rate and lower the sintering temperature for ceramics. The combination of lower sintering temperature and faster sintering rates may allow SLFS to be used for ceramic additive manufacturing. In this work, we study the effects of moisture on SLFS of yttria-stabilized zirconia ceramic. We compare the effects of processing parameters on the initiation of SLFS for samples exposed to a range of moisture levels.

null

['Sinico, M.', 'Ranjan, R.', 'Moshiri, M.', 'Ayas, C.', 'Langelaar, M.', 'Witvrouw, A.', 'van Keulen, F.', 'Dewulf, W.']

2021-11-30T19:54:36Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90528', 'http://dx.doi.org/10.26153/tsw/17447']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['topology optimization', 'laser powder bed fusion', 'mold insert']

A Mold Insert Case Study on Topology Optimized Design for Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/fa3d7107-5752-40db-952d-35b61533d1b9/download

University of Texas at Austin

The Additive Manufacturing (AM) of injection molding inserts has gained popularity during recent years primarily due to the reduced design-to-production time and form freedom offered by AM. In this paper, Topology Optimization (TO) is performed on a metallic mold insert which is to be produced by the Laser Powder Bed Fusion (LPBF) technique. First, a commercially available TO software is used, to minimize the mass of the component while ensuring adequate mechanical response under a prescribed loading condition. The commercial TO tool adopts geometry-based AM constraints and achieves a mass reduction of ~50 %. Furthermore, an in-house TO method has been developed which integrates a simplified AM process model within the standard TO algorithm for addressing the issue of local overheating during manufacturing. The two topology optimized designs are briefly compared, and the advantages of implementing manufacturing constraints into the TO algorithm are discussed.

null

['Zhirnov, I.', 'Doubenskaia, M.', 'Kotoban, D.']

2021-11-03T22:13:23Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89949

eng

2017 International Solid Freeform Fabrication Symposium

Open

['thermographic monitoring', 'single-track degradation', 'single-track', 'selective laser melting']

Monitoring of Single-Track Degradation in the Process of Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2d0118d3-b0c7-403b-8e5d-da7c4f586710/download

University of Texas at Austin

Selective laser melting machines provide the optimal working parameters for manufacturing during the process. However, the laser interaction with metal powder is an unstable. The gasdynamic flows make powder particles move and escape from the melt pool. This phenomenon leads to an irregular distribution of the material volume being remelted. Since the energy is constant during the process, single-tracks with different geometry are appeared and their superposition forms the 3D-object. To detect the process abnormality of stable track formation there was developed a control system based on morphological analysis of thermal image obtained by IR-camera. The temperature field distribution along the image matrix’s row with the maximum temperature was used as influencing factor on stable track formation. Roughness was reduced from 39.9 to 6.6 µm by using control system with the same process parameters. The obtained results can be applied in industrial SLM machines with the integrated active control system.

null

['Ziemian, C.W.', 'Cipoletti, D.E.', 'Ziemian, S.N.', 'Okwara, M.N.', 'Haile, K.V.']

2021-10-13T19:36:18Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88770', 'http://dx.doi.org/10.26153/tsw/15704']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['fused deposition modeling', 'monotonic tensile fatigue', 'cyclic tensile fatigue', 'tensile behavior', 'ABS components']

Monotonic and Cyclic Tensile Properties of ABS Components Fabricated by Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9107bcbf-ec33-4246-ac3d-ed0aaf4b2ce0/download

null

An investigation of tensile strength and cyclic tension-tension fatigue behavior has been performed on layered ABS components fabricated by fused deposition modeling (FDM). Experimentation was designed to focus specifically on the effect of specimen mesostructure on monotonic tensile behavior and tensile-fatigue life. Analyzed mesostructures include unidirectional laminae with parallel fiber orientations ranging from θ = 0° (aligned with the loading axis) to θ = 90° (perpendicular to the loading axis), and alternating laminae with a layering pattern of θ°/(θ-90°) fiber orientations. The unidirectional 0° specimens achieved the greatest tensile strength and effective elastic modulus, while the alternating +45°/-45° specimens displayed the best fatigue performance of the specimens tested. Results highlight the anisotropic behavior of FDM components and suggest that the tensile behavior is improved by aligning the fibers of unidirectional laminae more closely with the axis of the applied stress. In addition, the specimens with θ°/(θ-90°) fiber orientations displayed incrementally improved tensile properties and fatigue performance from an apparent offsetting effect that results from alternating laminae. The fracture surfaces of the specimens were analyzed using scanning electron microscopy in order to gain further insights into the fatigue damage and failure mechanisms.

null

['Xian, Y.', 'Rosen, D.W.']

2021-11-09T19:52:01Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90146', 'http://dx.doi.org/10.26153/tsw/17067']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['moving morphable components', 'MMC', 'topology optimization', 'support structures', 'material anisotropy', 'additive manufacturing']

Morphable Components Topology Optimization for Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e3342766-8fd1-4b2e-ab3c-70d297035c3a/download

University of Texas at Austin

This paper addresses two issues: 1. Topology optimization (TO) yields designs that may require support structures if additively manufactured, which increase material and clean-up costs. 2. Material anisotropy is induced during additive manufacturing, which results in inaccurate TO results if such material properties are not included in the algorithm. This paper, based on a moving morphable components (MMC) approach where structure is composed of several building blocks, introduces constraints for minimum build angle, as well as a penalty constraint for building blocks with no support material below, so that the TO output is completely printable. Additionally, orthotropic material properties are integrated in the optimization. In a separate optimization algorithm, each building block is assumed to have its own fiber orientation.

null

['Dwivedi, Rajeev', 'Kovacevic, Radovan']

2020-02-17T14:21:31Z

8/4/04

Mechanical Engineering

null

['https://hdl.handle.net/2152/79996', 'http://dx.doi.org/10.26153/tsw/7021']

eng

2004 International Solid Freeform Fabrication Symposium

Open

Solid Freeform Fabrication

Morphing Based Approach for Process Planning for Fabrication of Geometries and the Control of Material Composition

Conference paper

https://repositories.lib.utexas.edu//bitstreams/762278fd-9bd9-48d2-8ec8-fc8bcca9ce7f/download

null

The inherent limitation of most of the solid freeform fabrication is the deposition in form of layers. Artificial imposition of the process for the desired geometric morphology and the functional gradience of material limits the accuracy of the workpiece. Mathematical morphing of geometry and the material gradience allows a smooth variation across the part geometry and the material composition of the part. The paper describes a framework for process planning and implementation of fabrication of geometries and control of the material composition. Simulation results for the suggested approach are described in the paper.

null

['Saint John, David B.', 'Joshi, Sanjay B.', 'Simpson, Timothy W.', 'Qu, Meng', 'Rowatt, John David', 'Lou, Yucun']

2021-10-26T20:18:02Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89575

eng

2016 International Solid Freeform Fabrication Symposium

Open

['powder bed fusion', 'Inconel 718', 'morphology', 'grain texture', 'as-deposited', 'heat treated']

Morphology and Grain Texture in As-Deposited and Heat Treated Inconel 718 Structures Produced using Laser-Based Powder Bed Fusion

Conference paper

https://repositories.lib.utexas.edu//bitstreams/65dc8f17-3cb5-4228-b555-7e80070dfcec/download

University of Texas at Austin

With increasing interest in the use of powder bed fusion (PBF) processes for additive manufacturing, understanding the relationship between as-deposited and heat treated states and the intrinsic anisotropy of fabricated parts has become critical for its successful application. This phenomenon has been studied and reported extensively for Inconel 718 parts fabricated using PBF for aerospace applications, but few reports exist on the morphology and grain texture of Inconel 718 parts fabricated for oil and gas applications, which have different demands. This work demonstrates that the anisotropy in Inconel 718 parts produced using laser-based PBF is not entirely removed by subsequent heat treatments, and it may be an artifact of the as-deposited grain structure, whose elongated grains may stretch through several melt pools. The as-built material is observed to exhibit some texturing, with (001) being the preferential growth direction. Despite some residual anisotropy, heat treatments are sufficient to provide material qualities that meet specification, even without the use of a HIP (hot isostatic pressing) step. It is hypothesized that similarly elongated grain structures may explain the anisotropy observed in other materials systems employed in PBF additive manufacturing processes.

null

['Taylor, C. Martin', 'Childs, T.H.C.', 'Hauser, C.']

2019-10-25T16:03:04Z

2002

Mechanical Engineering

null

['https://hdl.handle.net/2152/77440', 'http://dx.doi.org/10.26153/tsw/4529']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Morphology

Morphology of Direct SLS-Processed Stainless Steel Layers

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3524c212-fd11-471c-9e2e-435da8c6b823/download

null

This paper discusses work done to analyse the shape of stainless steel layers generated by direct selective laser sintering (SLS). Laser power, scan spacing and scanning speed have been varied, to investigate their effect on geometry. The relationship between scanning parameters and the qualities of sintered parts (dimensional uniformity, porosity and scanned track shape) is described. A PC-based finite element code, developed to simulate SLS, has been modified to match the conditions of experiments discussed above. A comparison is made between computer-generated and experimentally-generated parts.

null

['Jouaneh, Musa', 'Stucker, Brent']

2019-11-20T15:44:22Z

2003

Mechanical Engineering

null

['https://hdl.handle.net/2152/78460', 'http://dx.doi.org/10.26153/tsw/5545']

eng

2003 International Solid Freeform Fabrication Symposium

Open

Fabrication

A Motion Planning Approach for Fabrication of Complex 3-D Shapes in a LENS� Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/751a38c7-7064-4e82-b461-0b1e5aa40797/download

null

This paper discusses an approach for planning the motion of the laser deposition head relative to the part for fabrication of complex 3-D shapes such as parts with overhangs, branches, and internal cavities in direct metal deposition processes such as the LENS‘ process. The proposed approach is based on slicing the solid model of the part into equal-thickness slices perpendicular to the normal build direction and formulating a motion planning strategy based on the properties of these slices. The paper discusses the four sub-approaches that are proposed to handle a variety of complex 3-D shapes parts.

null

Jouaneh, Musa

2019-10-30T16:56:11Z

2002

Mechanical Engineering

null

['https://hdl.handle.net/2152/78193', 'http://dx.doi.org/10.26153/tsw/5282']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Cladding

Motion Planning for Cladding Operations in a 5-Axis LENS� Machine

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d9102ce0-2d9e-466f-9ba4-f217b478b682/download

null

This paper presents a motion planning approach for some basic part shapes that require 5-axis motion control in a LENS machine. The paper discusses an approach that allows a cladding layer to be deposited on a cylindrical or a semi-spherical part for re-build operations. For cylindrical parts, the deposited layer could take the form of a tube, a spiral, or stepped/tappered tube. The approach allows arbitrary values for the parameters of these layers, and automatically translates the part parameters into a motion control program to run the LENS machine. The developed methodology was tested on an Optomec 850 machine, and the results were successful.

null

['Zong, Guisheng', 'Marcus, Harris L.']

2018-04-17T19:31:59Z

1991

Mechanical Engineering

doi:10.15781/T2TD9NR56

http://hdl.handle.net/2152/64356

eng

1991 International Solid Freeform Fabrication Symposium

Open

['Center for Materials Science and Engineering', 'SALD', 'pyrolytic']

Moving Boundary Transport Phenomena in Selective Area Laser Deposition Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5e9bf252-57b5-4b2d-a768-f7960b3241f9/download

null

The overall selective area laser deposition process was modeled using the two-layer, three dimensional solid phase heat transfer with the moving boundary condition considered, gas phase mass transfer, and film growth coupled equations. A modified front-tracking finite difference method was used to solve the moving boundary heat conduction in thick deposits. The results correlate with the experimental observations.

null

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

2020-03-09T14:56:19Z

2007

Mechanical Engineering

null

['https://hdl.handle.net/2152/80191', 'http://dx.doi.org/10.26153/tsw/7210']

eng

2007 International Solid Freeform Fabrication Symposium

Open

Fused Deposition Modeling

Multi Objective Optimisation of Build Orientation for Rapid Prototyping with Fused Deposition Modeling (FDM)

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5286f4f8-8193-4c7c-b21d-01b9d64ca599/download

null

The ability to select the optimal orientation of build up is one of the critical factors since it affects the part surface quality, accuracy, build time and part cost. Various factors to be considered in optimisation of build orientation for FDM are build material, support material, build up time, surface roughness and total cost. Experiments were carried out and results are analysed for varying build orientation for primitive geometries like cylinder. An appropriate weighting factor has been considered for various objective functions depending on the specific requirement of the part while carrying out multi-objective optimisation. These analyses will help process engineers to decide proper build orientation.

null

['Liou, Frank', 'Ruan, Jianzhong', 'Sparks, Todd E.']

2021-09-30T19:10:58Z

9/23/10

Mechanical Engineering

null

['https://hdl.handle.net/2152/88283', 'http://dx.doi.org/10.26153/tsw/15224']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['Multi-Axis Planning System', 'hybrid laser metal deposition processes', 'multi-axis layered manufacturing', 'automated fabrication']

Multi-Axis Planning System (MAPS) for Hybrid Laser Metal Deposition Processes

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4271887e-521a-49fc-a6e7-41bb57d25413/download

University of Texas at Austin

This paper summarizes the research and development of a Multi-Axis Planning System (MAPS) for hybrid laser metal deposition processes. The project goal is to enable the current direct metal deposition systems to fully control and utilize multi-axis capability to make complex parts. MAPS allows fully automated process planning for multi-axis layered manufacturing to control direct metal deposition machines for automated fabrication. Such a capability will lead to dramatic reductions in lead time and manufacturing costs for high-value, low-volume components with high performance material. The overall approach, slicing algorithm, machine simulation for planning validation, and the planning results will be presented.

null

['Surovi, N.A.', 'Soh, G.S.']

2024-03-26T23:11:49Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124444', 'https://doi.org/10.26153/tsw/51052']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['wire arc additive manufacturing', 'geometric defect']

MULTI-BEAD AND MULTI-LAYER PRINTING GEOMETRIC DEFECT IDENTIFICATION USING SINGLE BEAD TRAINED MODELS

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7948b303-87b3-4d98-8191-6301f1d54b2d/download

University of Texas at Austin

In Wire Arc Additive Manufacturing (WAAM), a geometric defect is a defect that creates voids in the final printed part due to incomplete fusion between two non-uniform overlapping bead segments. Such a defect posesthe onset of a severe problem during multi-bead prints. In our earlier work, a methodology has been developed to construct machine learning (ML)-based modelsto identify geometrically defective bead segments using acoustic signals. In this paper, we investigate the performance of these single-bead segments trained defect detection model scalability for identifying voids during multi-bead prints. A comparative study of the performance of a variety of ML models is explored based on Inconel 718 material printing. The results show that the single bead segments-based defect identification model can effectively identify defective and non-defective segments in both single-layer multi-bead printing and multi-layer multibead printing.

null

['Heeling, T.', 'Zimmermann, L.', 'Wegener, K.']

2021-10-28T19:52:15Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89684

eng

2016 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', 'multi-beam strategies', '316L']

Multi-Beam Strategies for the Optimization of the Selective Laser Melting Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ee1bf77f-af0f-45ed-b549-47a3e3755466/download

University of Texas at Austin

The additive manufacturing of metal parts is of increasing importance for various industry sectors, but processes like selective laser melting are still lacking of robustness especially in the case of hard to process materials. The local adjustment of temperature fields around the melt pool seems promising to decrease melt pool and stress related defects because the boundary conditions can be tailored to positively influence the melt pool dynamics and lifetime as well as the temperature gradients which are the main reason for distortion and cracking. Therefore a selective laser melting laboratory machine was built up which features two independent lasers and beam deflection units which are adapted to synchronization. To discuss the usability of different synchronized multi-beam strategies for further process improvement, computational and experimental evaluations are used to investigate the strategies‘ influences on the process dynamics of the selective laser melting process.

null

['Singh, Prabhjot', 'Dutta, Debasish']

2019-11-20T16:39:33Z

2003

Mechanical Engineering

null

['https://hdl.handle.net/2152/78478', 'http://dx.doi.org/10.26153/tsw/5563']

eng

2003 International Solid Freeform Fabrication Symposium

Open

Layered Deposition

Multi-Direction Layered Deposition: An Overview of Process Planning Methodologies

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5b9272a6-a9d9-4e35-a846-7995b17cffc2/download

null

Layered Manufacturing (LM) techniques build a part by adding thin layers of material. In many LM processes overhangs require the deposition of sacrificial supports resulting in an increase in the build time, wastage of material and costly post-processing. This has led to the development of LM systems which can deposit material along multiple directions and eliminate the need for supports. We survey the configurations of available multi-direction deposition systems. An overview of the process planning challenges is presented. Literature on process planning methodologies is reviewed.

null

['Ding, D.', 'Pan, Z.', 'Cuiuri, D.', 'Li, H.', 'Larkin, N.', 'van Duin, S.']

2021-10-21T15:48:25Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89402

eng

2015 International Solid Freeform Fabrication Symposium

Open

['robotic wire-feed additive manufacturing', 'multi-directional slicing', 'CAD models', 'STL models']

Multi-Direction Slicing of STL Models for Robotic Wire-Feed Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b1299549-aaaf-4b26-9f13-2f44ecf25668/download

University of Texas at Austin

Robotic wire-feed additive manufacturing technology is possible to directly fabricate metallic overhangs without support structures through multi-direction deposition. To automatically produce complex components with overhangs, an efficient multi-direction slicing algorithm to slice CAD models into a set of proper layers is required. This paper reports the concept and implementation of a new strategy for multi-direction slicing of CAD models represented in STL format. An input STL model is firstly decomposed into sub-volumes using a simple curvature-based volume decomposition method. Accordingly, each sub-volume is able to be built in a single direction. Then a depth-tree structure is introduced to regroup the decomposed sub-volumes and provide the slicing sequences. Consequently, sub-volumes are separately sliced along their associated appropriate build directions in sequence. The proposed multi-direction slicing strategy is shown to be simple and efficient for STL models with sharp edges.

null

['Bagchi, Amit', 'Beesley, Robert']

2018-10-03T15:38:18Z

1994

Mechanical Engineering

doi:10.15781/T2HQ3SH86

http://hdl.handle.net/2152/68650

eng

1994 International Solid Freeform Fabrication Symposium

Open

['Solid free-form fabrication', 'Photolithography', 'selective laser sintering']

Multi-layered Composites Using Photolithography

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b532c87c-f94f-4147-b368-54e8627a7583/download

null

The mechanical properties of the parts made using solid freeform fabrication technologies are limited by their resins used. Previous research has shown that the mechanical properties of these parts can be enhanced substantially by using glass and fiber reinforcements. However, all of the published data is for single layered composites, which does not demonstrate its feasibility to manufacture multilayered real objects. In this paper experiments carried out to build multi-layered parts with glass fiber tow as reinforcement in a matrix of photopolymeric resin are described. These specimens are then tested in uniaxial tension and three point bending to determine their improvement in mechanical properties. The experimental data shows that the tensile strength and tensile modulus increased linearly with the volume fraction of the fiber in the composite, thus demonstrating that the trends observed in single layer composites can be also seen in multi-layered composites.

null

['Bondi, Scott N.', 'Johnson, Ryan W.', 'Eikhatib, Tarek', 'Gillespie, Josh', 'Mi, Jian', 'Lackey, W. Jack']

2019-10-22T18:10:37Z

2002

Mechanical Engineering

null

['https://hdl.handle.net/2152/76331', 'http://dx.doi.org/10.26153/tsw/3420']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Deposition

Multi-Material and Advanced Geometry Deposition via Laser Chemical Vapor Deposition

Conference paper

https://repositories.lib.utexas.edu//bitstreams/067ed020-d727-4f1c-8022-5e7801349b8b/download

null

Laser Chemical Vapor Deposition (LCVD) as a manufacturing process holds the potential to build compositionally and geometrically unique objects. Georgia Tech’s LCVD system has been used in the past to create three-dimensional and laminate structures out of carbon. Recently molybdenum and boron nitride were successfully deposited and upgrades to the system have allowed for higher spatial resolutions and more varied geometric capabilities. Upgrades include the addition of a fourth linear stage and implementation of an argon ion laser. Detailed thermal and fluid modeling have provided more insight as to the important parameters and characteristics of the LCVD process.

This work is supported by the National Science Foundation.

null

['Lipton, Jeffrey', 'Arnold, Dave', 'Nigl, Franz', 'Lopez, Nastassia', 'Cohen, Dan', 'Norén, Nils', 'Lipson, Hod']

2021-10-01T00:10:27Z

9/23/10

Mechanical Engineering

null

['https://hdl.handle.net/2152/88304', 'http://dx.doi.org/10.26153/tsw/15245']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['Solid Freeform Fabrication', 'additive manufacturing', 'food printing', 'food processing', 'multi-material constructs']

Multi-Material Food Printing with Complex Internal Structure Suitable for Conventional Post-Processing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c7c036fd-4f58-4b5a-95f3-5d59437c989b/download

University of Texas at Austin

Solid Freeform Fabrication (SFF) of food provides an exciting application for additive manufacturing technologies. A variety of materials has been used to demonstrate food printing. However, these materials were not suited for traditional food processing techniques (Baking, slow cooking, frying, etc) and thus eliminating the majority of today‟s consumed food. We demonstrated new materials suitable for baking, broiling and frying. Turkey, scallop, celery were processed and modified using transglutaminase to enable them to be slow cooked or deep-fried after printing. Mutli-material constructs of turkey meat and celery were successfully printed. A cookie recipe was modified to be printable while retaining shape during baking. By adding cocoa powder to the modified recipe a second, visually and differently tasting material was created. A complex shape of the cocoa modified material was printed within a block of the modified material. The complex internal geometry printed was fully preserved during baking.

null

['Patrick, Steven', 'Nycz, Andrzej', 'Noakes, Mark']

2021-11-18T16:49:21Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90424', 'http://dx.doi.org/10.26153/tsw/17345']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['slicing software', 'slicing', 'process planning', 'multi-material', 'additive manufacturing', 'metal big area additive manufacturing', 'MBAAM', 'Oak Ridge National Laboratory']

Multi-Material Process Planning for Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ec57a3cb-8475-4706-82f8-abb06dadb5a0/download

University of Texas at Austin

A key process in additive manufacturing is converting a 3D model into a set of instructions that a robot can parse and implement. This process is commonly referred to as slicing. Oak Ridge National Laboratory’s (ORNL) Metal Big Area Additive Manufacturing (MBAAM) team at the Manufacturing Demonstration Facility (MDF) has developed a slicing software that generates instructions for multiple materials within the same part. The benefits of using multiple materials are lower cost, fewer voids, and greater control over the print. However, a significant challenge arose when the two different materials had different layer heights and bead widths. A layer of complexity was added not only when the material changed from layer to layer, but also when different materials were used within a single layer. These challenges were addressed by assigning bead types and profile types to printing regions and layers, respectively.

null

['Griffith, Michelle L.', 'Harwell, Lane D.', 'Romero, J. Tony', 'Schlienger, Eric', 'Atwood, Clint L.', 'Smugeresky, John E.']

2018-12-05T19:32:31Z

1997

Mechanical Engineering

doi:10.15781/T21J97T99

http://hdl.handle.net/2152/71406

eng

1997 International Solid Freeform Fabrication Symposium

Open

['CAD', 'alloys']

Multi-Material Processing By Lens

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4255f87d-bc6c-4ddc-a267-18a095a0ea5e/download

null

During the past few years, solid freeform fabrication has evolved into direct fabrication of metallic components using computer aided design (CAD) solid models. [1-4] Laser Engineered Net Shaping (LENS™) is one such technique [5-7] being developed at Sandia to fabricate high strength, near net shape metallic components. In the past two years a variety of components have been fabricated using LENS™ for applications ranging from prototype parts to injection mold tooling. [8] To advance direct fabrication capabilities, a process must be able to accommodate a wide range ofmaterials, including alloys and composites. This is important for tailoring certain physical properties critical to component performance. Examples include graded deposition for matching coefficient ofthermal expansion between dissimilar materials, layered fabrication for novel mechanical properties, and new alloy design where elemental constituents and/or alloys are blended to create new materials. In this paper, we will discuss the development ofprecise powder feeding capabilities for the LENSTM process to fabricate graded or layered material parts. We also present preliminary results from chemical and microstructural analysis.

null

['Ott, M.', 'Zach, M.F.']

2021-09-30T13:44:32Z

9/23/10

Mechanical Engineering

null

['https://hdl.handle.net/2152/88250', 'http://dx.doi.org/10.26153/tsw/15191']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['additive layer manufacturing', 'multi-material processing', 'material flexibility', 'material properties', 'hot work steel', 'tungsten carbide/cobalt']

Multi-Material Processing in Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d3b43fdf-71cd-4be3-bb28-27ae19d9e319/download

University of Texas at Austin

One of the most important advantages of additive layer manufacturing (ALM) is the ability to produce parts with high geometric complexity in a very economical manner. However, only little effort has been taken in order to enhance aspects of material flexibility of ALM. A modified manufacturing process was developed and different stages concerning the dimensions of multi-material complexity are defined. The technological base being selective laser melting, two varying metallic materials were fused within each layer. Therefore, a new recoating mechanism for non-cohesive powders has been developed. To increase lifetime of tools with abrasive wear environment, hot work steel and tungsten carbide/cobalt have been combined. A tooling insert has been chosen as an example of application.

null

['Chang, Chih-Chiang M.', 'Angelini, Thomas E.', 'Bova, Frank J.', 'Banks, Scott A.']

2021-11-30T20:09:48Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90532', 'http://dx.doi.org/10.26153/tsw/17451']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['soft matter fabrication', '3D printing', 'robotics', 'additive manufacturing', 'multi-material']

Multi-Material Soft Matter Robotic Fabrication: A Proof of Concept in Patient-Specific Neurosurgical Surrogates

Conference paper

https://repositories.lib.utexas.edu//bitstreams/bb8affa1-43c8-4d57-9b7d-677601af93d2/download

University of Texas at Austin

Soft matter 3D printing provides the capability to fabricate 3D structures by depositing hydrogel inks in granular gel support material. To date, there has been little work reported using this method to fabricate complex-shaped models with multiple materials in a timely fashion. The aim of this project is to introduce recent research of multi-material soft-matter extrusion and deposition for fast freeform fabrication of 3D structures, and to present a process for automating the fabrication of patient-specific neuro-anatomic models for surgical training. A compact design of multi-material extrusion printhead is described, which is capable of fabricating 3D structures from multiple inks. This approach provides a fast and efficient way to convert a virtual volumetric model into a physical extruded hydrogel structure using the multi-material soft-matter robotic fabrication system. In addition to fabrication of neurosurgical phantoms, the capabilities we describe may be useful in broader application contexts such as general soft matter robotic fabrication, pharmaceutical testing, and extrusion-based bioprinting.

null

['Arcaute, Karina', 'Zuverza, Nubia', 'Mann, Brenda', 'Wicker, Ryan']

2020-03-10T15:12:07Z

8/27/07

Mechanical Engineering

null

['https://hdl.handle.net/2152/80214', 'http://dx.doi.org/10.26153/tsw/7233']

eng

2007 International Solid Freeform Fabrication Symposium

Open

stereolithography

Multi-Material Stereolithography: Spatially-Controlled Bioactive Poly(Ethylene Glycol) Scaffolds for Tissue Engineering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c4b7ecd7-728b-48c2-8d44-65bc033a5adf/download

null

Challenges remain in tissue engineering to control the spatial and temporal mechanical and biochemical architectures of scaffolds. Unique capabilities of stereolithography (SL) for fabricating multi-material spatially-controlled bioactive scaffolds were explored in this work. To accomplish multi-material builds with implantable materials, a new mini-vat setup was designed, constructed and placed on top of the existing build platform to allow for accurate and selfaligning X-Y registration during fabrication. Precise quantities of photocrosslinkable solution were added to and removed from the mini-vat using micro-pipettes. The mini-vat setup allowed the part to be easily removed and rinsed and different photocrosslinkable solutions could be easily removed and added to the vat to aid in multi-material fabrication. Two photocrosslinkable hydrogel biopolymers, poly(ethylene glycol dimethacrylate) (PEG-dma, molecular wt 1,000) and poly(ethylene glycol)-diacrylate (PEG-da, molecular wt 3,400), were used as the primary scaffold materials, and controlled concentrations of fluorescently labeled dextran or bioactive PEG were prescribed and fabricated in different regions of the scaffold using SL. The equilibrium swelling behavior of the two biopolymers after SL fabrication was determined and used to design constructs with the specified dimensions at the swollen state. Two methods were used to measure the spatial gradients enabled by this process with multi-material spatial control successfully demonstrated down to 500-µm. First, the presence of the fluorescent component in specific regions of the scaffold was analyzed with fluorescent microscopy. Second, human dermal fibroblast cells were seeded on top of the fabricated scaffolds with selective bioactivity, and phase contrast microscopy images were used to show specific localization of cells in the regions patterned with bioactive PEG. The use of multi-material SL and the relative ease of conjugating different bioactive ligands or growth factors to PEG allows for the fabrication of tailored three-dimensional constructs with specified spatially-controlled bioactivity.

null

['Aguiló, M.A.', 'Warner, J.E.']

2021-11-04T19:55:55Z

2017

Mechanical Engineering

null

['https://hdl.handle.net/2152/90015', 'http://dx.doi.org/10.26153/16936']

eng

2017 International Solid Freeform Fabrication Symposium

Open

['stochastic reduced order model', 'multi-material topology optimization', 'structural topology optimization', 'topology optimization', 'uncertainty']

Multi-Material Structural Topology Optimization Under Uncertainty via a Stochastic Reduced Order Model Approach

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a3f59ee4-b806-4704-ad4d-2532346a5074/download

University of Texas at Austin

This work presents a stochastic reduced order modeling approach for the solution of uncertainty aware, multi-material, structural topology optimization problems. Uncertainty aware structural topology optimization problems are computationally complex due to the number of model evaluations that are needed to quantify and propagate design uncertainties. This computational complexity is magnified if high-fidelity simulations are used during optimization. A stochastic reduced order model (SROM) approach is applied to 1) alleviate the prohibitive computational cost associated with large-scale, uncertainty aware, structural topology optimization problems; and 2) quantify and propagate inherent uncertainties due to design imperfections. The SROM framework transforms the uncertainty aware, multi-material, structural topology optimization problem into a deterministic optimization problem that relies only on independent calls to a deterministic analysis engine. This approach enables the use of existing optimization and analysis tools for the solution of uncertainty aware, multi-material, structural topology optimization problems.

null

['Janaki Ram, G. D.', 'Robinson, C.', 'Stucker, B. E.']

2020-02-28T15:04:30Z

9/14/06

Mechanical Engineering

null

['https://hdl.handle.net/2152/80108', 'http://dx.doi.org/10.26153/tsw/7129']

eng

2006 International Solid Freeform Fabrication Symposium

Open

Ultrasonic consolidation

Multi-Material Ultrasonic Consolidation

Conference paper

https://repositories.lib.utexas.edu//bitstreams/316a7aa5-e0e8-41ef-a0e4-5cb9a653c56d/download

null

Ultrasonic consolidation (UC) is a recently developed direct metal solid freeform fabrication process. While the process has been well-demonstrated for part fabrication in Al alloy 3003 H18, including with intricate cooling channels, some of the potential strengths of the process have not been fully exploited. One of them is its flexibility with build materials and the other is its suitability for fabrication of multi-material and functionally graded material parts with enhanced functional or mechanical properties. Capitalizing on these capabilities is critical for broadening the application range and commercial utilization of the process. In the current work, UC was used to investigate ultrasonic bonding of a broad range of engineering materials, which included stainless steels, Ni-base alloys, brass, Al alloys, and Al alloy composites. UC multimaterial part fabrication was examined using Al alloy 3003 as the bulk part material and the above mentioned materials as performance enhancement materials. Studies were focused on microstructural aspects to evaluate interface characteristics between dissimilar material layers. The results showed that most of these materials can be successfully bonded to Al alloy 3003 and vice versa using the ultrasonic consolidation process. Bond formation and interface characteristics between various material combinations are discussed based on oxide layer characteristics, material properties, and others.

null

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

2019-11-20T15:50:19Z

2003

Mechanical Engineering

null

['https://hdl.handle.net/2152/78462', 'http://dx.doi.org/10.26153/tsw/5547']

eng

2003 International Solid Freeform Fabrication Symposium

Open

Multi-Material

A Multi-Material Virtual Prototyping System

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e1b21a2f-a30a-4f31-aad4-bb8e933a0890/download

null

This paper proposes a virtual prototyping system for digital fabrication of multimaterial prototypes. It consists mainly of a topological hierarchy-sorting algorithm for processing slice contours, and a virtual simulation system for visualisation and optimisation of multi-material layered manufacturing (MMLM) processes. The topological hierarchysorting algorithm processes the hierarchy relationship of complex slice contours. It builds a parent-and-son list that defines the containment relationship of the slice contours, and subsequently arranges the contours in an appropriate sequence which facilitates optimisation of toolpath for MMLM by avoiding redundant movements. The virtual simulation system simulates MMLM processes and provides vivid visualisation of the resulting multi-material prototypes for quality analysis and optimisation of the processes

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

['Espalin, David', 'Ramirez, Jorge', 'Medina, Francisco', 'Wicker, Ryan']

2021-10-06T21:56:33Z

8/15/12

Mechanical Engineering

null

['https://hdl.handle.net/2152/88456', 'http://dx.doi.org/10.26153/tsw/15393']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['fused deposition modeling', 'multi-materials', 'multi-technology', 'thermoplastic parts']

Multi-Material, Multi-Technology FDM System

Conference paper

https://repositories.lib.utexas.edu//bitstreams/80ce4603-a12c-4f42-81ed-544c1764f538/download

University of Texas at Austin

A multi-material, multi-technology FDM system was developed and constructed to enable the production of novel thermoplastic parts. Two legacy FDM systems were modified and installed onto a single manufacturing system to allow the strategic, spatially controlled thermoplastic deposition of multiple materials during the same build. Additionally, a build process variation utilizing more than two extrusions tips was employed to deposit thermoplastic materials using variable layer thicknesses and road widths. The hardware and control software is discussed as well as the potential applications of multi-material polymeric parts. Benefits of multiple material FDM include: 1) achieving aesthetic requirements by using polymers of different colors, and 2) attaining desired properties (e.g., bulk tensile/compressive/flexural strength, weight, thermal conductivity) by strategically combining layers and regions within layers of polymers that display different properties. Parts produced using the build process variation exhibited internal road with 1200 ± 39µm road width and 497 ± 11µm layer height while the contours measured 269 ± 18µm road width and 133 ± 3µm layer thickness. Additionally, for a 50.8mm by 50.8mm square section (25.4mm tall), the build process variation required 4.0 hours to build while the original strategy required 6.2 hours constituting a 35% reduction in build time.

null

['Khalil, S.', 'Nam, J.', 'Darling, A.', 'Sun, W.']

2020-02-20T18:38:00Z

2004

Mechanical Engineering

null

['https://hdl.handle.net/2152/80038', 'http://dx.doi.org/10.26153/tsw/7060']

eng

2004 International Solid Freeform Fabrication Symposium

Open

solid freeform fabrication

Multi-Nozzle Biopolymer Deposition for Freeform Fabrication of Tissue Constructs

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c827f801-78dc-4ca1-add5-d5fe50d56f08/download

null

Advanced freeform fabrication techniques have been recently used for the construction of tissue scaffolds because of the process repeatability and capability of high accuracy in fabrication resolution at the macro and micro scales. Among many applicable tissue scaffolding materials, polymeric materials have unique properties in terms of the biocompatibility and degradation, and have thus been widely utilized in tissue engineering applications. Hydrogels, such as alginate, has been one of the most important polymer scaffolding materials because of its biocompatibility and internal structure similarity to that of the extracellular matrix of many tissues, and its relatively moderate processing. Three-dimensional deposition has been an entreating freeform fabrication method of biopolymer and particularly hydrogel scaffolds because of its readiness to deposit fluids at ambient temperatures. This paper presents a recent development of biopolymer deposition based freeform fabrication for 3-diemnsinal tissue scaffolds. The system configuration of multi-nozzles used in the deposition of sodium alginate solutions and Poly-?- Caprolactone (PCL) are described. Studies on polymer deposition feasibility and structural formability are conducted, and the preliminary results are presented.

null

['Aboutaleb, Amir M.', 'Bian, Linkan', 'Shamsaei, Nima', 'Thompson, Scott M.', 'Rao, Prahalad K.']

2021-10-27T21:25:01Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89619

eng

2016 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'multi-objective optimization', 'fused filament fabrication', 'geometry accuracy optimization', 'design of experiments']

Multi-Objective Process Optimization of Additive Manufacturing: A Case Study on Geometry Accuracy Optimization

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4f750348-5ab4-4880-91aa-0268c4bb973a/download

University of Texas at Austin

Despite recent research efforts improving Additive Manufacturing (AM) systems, quality and reliability of AM built products remains as a challenge. There is a critical need to achieve process parameters optimizing multiple mechanical properties or geometry accuracy measures simultaneously. The challenge is that the optimal value of various objectives may not be achieved concurrently. Most of the existing studies aimed to obtain the optimal process parameters for each objective individually, resulting in duplicate experiments and high costs. In this study we investigated multiple geometry accuracy measures of parts fabricated by Fused Filament Fabrication (FFF) system. An integrated framework for systematically designing experiments is proposed to achieve multiple sets of FFF process parameters resulting in optimal geometry integrity. The proposed method is validated using a real world case study. The results show that optimal properties are achieved in a more efficient manner compared with existing methods.

null

['Paudel, Basil J.', 'Masoomi, Mohammad', 'Thompson, Scott M.']

2021-11-30T19:50:41Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90527', 'http://dx.doi.org/10.26153/tsw/17446']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['laser-powder bed fusion', 'optimization', 'heat sink', 'topology', 'fin design']

Multi-Objective Topology Optimization of Additively Manufactured Heat Exchangers

Conference paper

https://repositories.lib.utexas.edu//bitstreams/940219e2-230b-4a7e-a6eb-3687ed6ed45d/download

University of Texas at Austin

The higher design flexibility offered by additive manufacturing (AM) allows for radical improvements in the design and functionality of legacy parts. In this study, a flat-plate heat exchanger is designed and optimized using the ANSYS topology optimization module. Unlike conventional numerical optimization tools, the current optimization approach employs multiple objective functions, including mass reduction and maximization of heat transfer efficiency. Two unique, initial designs were used for ‘seeding’ the multi-objective topology optimization (TO) routines and the results are compared and discussed. Topology design and operating (boundary condition) variables were varied to elucidate major design sensitivities. The predicted heat transfer within the topology-optimized parts was validated using separate numerical methods. Constraints related to flow pressure drops and additive manufacturability were enforced. In both cases, the optimal design performed significantly better than the conventional heat exchanger in terms of thermal efficiency per unit mass.

null

['MN, Kishore', 'Qian, Dong', 'Li, Wei']

2024-03-26T20:02:43Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124384', 'https://doi.org/10.26153/tsw/50992']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['directed energy deposition', 'low temperature', 'sub-freezing deposition', 'computational fluid dynamics', 'multiphysics modeling']

MULTI-PHYSICS MODELING OF LOW-TEMPERATURE DIRECTED ENERGY DEPOSITION OF STAINLESS STEEL 316L

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2390a86e-ee67-430a-abe9-4ceee2a538db/download

University of Texas at Austin

The Directed energy deposition (DED) process is greatly influenced by the ambient temperature at on-site repair. In Northern Hemisphere locations, DED is particularly influenced by sub-freezing temperatures. However, its influence on the process is not yet studied. This critical gap is fulfilled in this research through a multi-physics computational fluid dynamics (CFD) modeling of the lowtemperature DED of the SS316L powders. The model is validated with test cases: −3°𝐶 for subfreezing and 20°𝐶 for room temperature cases using a cryogenic DED platform. The modeling involves powder spray, local melting, rapid cooling, solidification, evaporation, and fluid-gas interactions. The results show, at sub-freezing, the molten pool is ~63% bigger with the maximum temperature reduced by ~9.5%. The deposition saw an increase in width by ~8.6% and height by ~26% than the room temperature case. Overall, the versatile modeling-experimental platform helps study cryogenic DED cases for in-space additive manufacturing.

null

['Cheng, Bo', 'Li, Xiaobai', 'Tuffile, Charles', 'Ilin, Alexander', 'Willeck, Hannes', 'Hartel, Udo']

2021-11-15T21:02:59Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90270', 'http://dx.doi.org/10.26153/tsw/17191']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', 'SLM', 'discrete element method', 'DEM', 'powder bed packing', 'melt pool', 'computational fluid dynamics', 'CFD', 'volume of fluid', 'VOF']

Multi-Physics Modeling of Single Track Scanning in Selective Laser Melting: Powder Compaction Effect

Conference paper

https://repositories.lib.utexas.edu//bitstreams/cfb54c01-7c1f-490b-bff0-ab2a35984b4d/download

University of Texas at Austin

In this work, a microscale computational fluid dynamics (CFD) model was developed for selective laser melting (SLM) process simulation using FLOW3D to study the effect of powder bed recoating methods on melt pool characteristics. The discrete element method (DEM) was used to simulate both the blade and the roller-compaction recoating processes, where layers of powder particles with different sizes were generated on a solid substrate. Melt pools propagating through the powder beds were simulated using the Volume of Fluid (VOF) method that tracks the free surface evolution of melt pools that are produced when a Gaussian distributed moving laser heat source, with given process parameters, irradiates the powder bed. Thermal and fluid material properties were incorporated in the model to improve simulation accuracy, and melt pool validation from single-track laser scanning simulation was performed.

null

['Lehder, E.F.', 'Ashcroft, I.A.', 'Wildman, R.D.', 'Maskery, I.', 'Cantu, L.R.']

2021-11-30T20:07:44Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90531', 'http://dx.doi.org/10.26153/tsw/17450']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['bone scaffolds', 'computational modelling', 'minimal surfaces', 'tissue regeneration', 'level set method', 'multi-scale']

A Multi-Scale Computational Model to Predict the Performance of Cell Seeded Scaffolds with Triply Periodic Minimal Surface Geometries

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0b59b3bf-a5d7-4d73-a623-e8afc8f0d7be/download

University of Texas at Austin

Bone scaffolds are required to replace the painful and dangerous process of bone grafting, currently the gold standard for treating open bone fractures. Tissue engineering scaffolds work best when there is a high amount of surface area for biological cells to attach. Triply Periodic Minimal Surface (TPMS) geometries offer high ratios of surface area per volume. However, it is not yet clear which TPMS cell type would yield the fastest bone growth rate. In this study, we used a three-dimensional multi-scale model to predict the performance of scaffolds with four TPMS unit cell types (Primitive, Gyroid, Diamond and Lidinoid). At the micro-scale, the model simulates curvature-dependent tissue growth, while at the macro-scale the model uses FEA to ensure the construct stiffness is acceptable. The Lidinoid unit cell type was found to yield the most bone growth after 40 days while also ensuring an acceptable scaffold stiffness.

null

['Botelho, L.', 'van Blitterswijk, R.H.', 'Khajepour, A.']

2021-12-07T18:32:07Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90751', 'http://dx.doi.org/10.26153/tsw/17670']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['laser additive manufacturing', 'machine learning', 'convolutional neural network']

Multi-track Geometry Prediction in Powder Fed Laser Additive Manufacturing Using Machine Learning

Conference paper

https://repositories.lib.utexas.edu//bitstreams/df4ec261-900c-48e6-b38a-95b9d49f5197/download

University of Texas at Austin

Laser additive manufacturing (LAM) allows for complex geometries to be fabricated without the limitations of conventional manufacturing. However, LAM is highly sensitive to small disturbances, resulting in variation in the geometry of the produced layer (clad). Therefore, in this research a monitoring algorithm is discussed with the capability of predicting the geometry of multiple tracks of added material. Though imaging can be used to measure the geometry of the melt pool during LAM, the appearance of the melt pool changes in multi-track processes due to the previous layers causing measurement errors. Hence, a machine learning algorithm may be able to accommodate for the changing melt pool appearance to improve accuracy. Images can be captured during LAM with visible-light and infrared sensors which may provide sufficient information for the geometry to be predicted. A convolutional neural network (CNN) can then use these images to estimate the geometry (height and width) during LAM processes.

null

['Folgar, C.E.', 'Folgar, L.N.', 'Cormier, D.']

2021-10-07T18:18:15Z

2013

Mechanical Engineering

null

['https://hdl.handle.net/2152/88498', 'http://dx.doi.org/10.26153/tsw/15432']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['laser sintering', 'direct printing', 'multifunctional material', 'part strength', 'electrical conductivity']

Multifunctional Material Direct Printing for Laser Sintering Systems

Conference paper

https://repositories.lib.utexas.edu//bitstreams/93cc0a72-bb1c-4767-89aa-9767bca10722/download

University of Texas at Austin

The research reports the development of advanced techniques for the direct print of materials into parts made by laser sintering. The present invention provides for the production of three-dimensional objects with improved build and support materials. The direct printed material may be metals, elastomers, ceramic, or any other material, which is typically different than the laser sintering material. Aspects of the technique include direct printed materials within laser sintered parts to improve part strength, provide multi-materials, provide electrical conductivity, and provide other desirable benefits to the part.

null

['Johannes, S.J.', 'Keicher, D.M.', 'Lavin, J.M.', 'Secor, E.B.', 'Whetten, S.R.', 'Essien, M.']

2021-11-09T18:51:19Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90116', 'http://dx.doi.org/10.26153/tsw/17037']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['aerosol jet printing', 'direct-write printing', 'circuit elements', 'toroidal inductor', 'additive manufacturing']

Multimaterial Aerosol Jet Printing of Passive Circuit Elements

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6bf96d30-27b2-4df2-af5c-bf00b1c73c9c/download

University of Texas at Austin

Recent advances in additive manufacturing technologies present opportunities for rethinking the design and fabrication of electronic components. An area of considerable interest for electronic printing is the production of multi-layered, multi-material passive components. This research focuses on the design and fabrication of a toroidal microinductor using a digital, direct-write printing platform. The toroidal inductor has a three layer design with a dielectric and core material printed in between the lower and upper halves of the conductive coil. The results of this work are discussed, including printer, ink, and processing requirements to successfully print the multi-layer, multi-material component. The inductance of several successful printed devices is measured and compared to predicted values. Overall, the results and lessons of this work provide guidance for future work in this growing field.

null

['Geiger, Martin', 'Greul, Matthias', 'Steger, Wilhelm', 'Sindel, Manfred']

2018-09-26T16:48:03Z

1994

Mechanical Engineering

doi:10.15781/T2348H18X

http://hdl.handle.net/2152/68581

eng

1994 International Solid Freeform Fabrication Symposium

Open

['Multiphase Jet Solidification', 'RP Technologies', '3D Modeler of Stratasys']

Multiphase Jet Solidification - a new process towards metal prototypes and a new data interface

Conference paper

https://repositories.lib.utexas.edu//bitstreams/34bc59a2-8ae9-463e-bc49-722b963e76fd/download

null

The production of metallic and ceramic parts with RP technologies is requested. Multiphase Jet Solidification (MJS) is a process which reveals good results to develop a commercial system due to this task. Low viscous materials (liquefied substances or powder-binder~pastes) are extruded through an x-y-z~ontrolled jet and parts of different materials e.g. stainless steel are fabricated layer by layer up to the final extension. basic principle of the process and the current results will be presented. A slice format was designed for MJS, but it is also usable for other technologies. The is development of a general slice interface for RP.

null

['Rangapuram, M.', 'Yang, M.', 'Babalola, S.', 'Newkirk, J.W.', 'Bartlett, L.N.', 'Liou, F.F.', 'Chandrashekhara, K.']

2023-03-30T16:12:24Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117698', 'http://dx.doi.org/10.26153/tsw/44577']

eng

2022 International Solid Freeform Fabrication Symposium

Open

Laser powder bed fusion

A Multiphysics Modeling Approach to Assess the Powder Bed Characteristics of High Strength Steel in Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f70de131-790e-4c59-b60d-7511af969643/download

null

Selective laser melting (SLM) is a type of additive manufacturing technique which uses a powder bed to form complex metal parts in a layer-by-layer process. The density of the powder bed in SLM affects the mechanical properties of the produced part. Good powder packing results in a higher powder bed density which in turn influences the quality of the produced part. In this work, a computational fluid dynamics (CFD) model was developed for the SLM process using Flow 3D software to study the effect of powder bed density on the melt pool characteristics of high strength steel. Discrete element method (DEM) was used to generate powder beds with realistic powder properties. The realistic powder properties of AF9628 were obtained using JMatPro software. The powder beds were irradiated with a moving laser heat source to study the melt pool characteristics. These models were validated with experimental results.

null

['Caglar, H.', 'Liang, A.', 'Mumtaz, K.']

2024-03-26T21:35:59Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124421', 'https://doi.org/10.26153/tsw/51029']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['laser powder bed fusion', 'diode area melting', 'Ti-6Al-4V', 'additive manufacturing']

MULTIPLE 450 nm DIODE LASER PROCESSING OF TI64 POWDER

Conference paper

https://repositories.lib.utexas.edu//bitstreams/aae75500-33e1-4a25-8eaf-dca7c7aecca2/download

University of Texas at Austin

Diode Area Melting (DAM) presents an alternative approach to traditional Laser Powder Bed Fusion (PBF-LB/M) approaches, integrating multiple individually addressable low-power fibre-coupled diode lasers into a laser head; these traverse across a powder bed to melt powdered feedstock. DAM research to date has focused on using low-power 808 nm lasers to process Ti6Al-4V (Ti64) powder. This work focuses on using multiple short wavelengths 450 nm 4W lasers to process Ti64 feedstock. Previous studies found that when processing Ti64, absorption was 11% higher using 450 nm lasers when compared to using 808 nm lasers and 14% higher than 1064nm laser. This work demonstrated the potential to use shorter wavelength lasers in DAM/LPBF for improved melting efficiency. Also, it aimed to examine the impact of 450 nm diode lasers on Ti64 and generate a parameter map for this material. It was found that low power (4W) multiple 450 nm diode lasers can successfully melt the Ti64 for AM applications with above 95% density.

null

['Leite, M.', 'Frutuoso, N.', 'Soares, B.', 'Ventura, R.']

2021-11-15T22:01:50Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90286', 'http://dx.doi.org/10.26153/tsw/17207']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['large parts', 'FDM', 'collaborative deposition heads']

Multiple Collaborative Printing Heads in FDM: The Issues in Process Planning

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1430a740-68fb-47b8-9e62-7117d98246c7/download

University of Texas at Austin

One of the main drawbacks of large-scale FDM is fabrication time, due to the use of a single deposition head. In this paper we propose a novel approach to tool-path generation for a system with multiple collaborative independent deposition heads. This system allows the size of the parts to increase considerably in comparison to regular FDM systems without the corresponding time increase. However, to enable the tool-path generation, the conventional process planning must be changed. Once the machine configuration is defined, (e.g. number and size of heads), the regions are attributed to each head as either static or dynamic. Then the layer is divided into domains, assigned to each head. A centralized tool-path planner then generates tool-paths, accounting for collisions and optimizing the fabrication time in the layer. The process repeating for all layers. Examples of this approach show reduced fabrication time and larger part dimensions than conventional systems.

null

['Wicker, Ryan', 'Medina, Francisco', 'Elkins, Chris']

2020-02-17T15:40:23Z

8/4/04

Mechanical Engineering

null

['https://hdl.handle.net/2152/80013', 'http://dx.doi.org/10.26153/tsw/7038']

eng

2004 International Solid Freeform Fabrication Symposium

Open

['multiple material stereolithography', 'rapid prototyping', 'micro-stereolithography']

Multiple Material Micro-Fabrication: Extending Stereolithography to Tissue Engineering and Other Novel Applications

Conference paper

https://repositories.lib.utexas.edu//bitstreams/61f2ec11-728b-433b-a70b-33cc55ffc399/download

null

A design for modifying an existing 3D Systems stereolithography (SL) apparatus 250/50 was developed to accommodate multiple material fabrication for building multi-material, multifunctional and multi-colored prototypes, models and devices. The machine was configured for automated access to an intermediate washing, curing, and drying unit that eliminated contamination between material vats and maintained accurate platform registration throughout the build process. Three vats were arranged on a rotating vat carousel, and each vat was adapted to actively maintain a uniform, desired level of material by including a recoating device and a material fill and removal system. A single platform was attached to an elevator mechanism (zstage) to traverse the platform to and from the vats and the washing, curing, and drying unit. The platform was mounted to the z-stage via an automated rotary stage to rotate the platform about a horizontal axis, thus providing angled building, washing, curing, and drying capabilities. A horizontal traversing mechanism was also designed to be optionally included to facilitate manufacturing between multiple SL cabinets, related SL apparatuses and/or other alternative manufacturing technologies. For micro-fabrication, linear and rotary stages were selected that provided ±1.0 µm repeatability and 0.1 µm resolution and ±2 arc sec repeatability and 0.13 arc sec resolution, respectively. The multi-material SL design presented here is capable of utilizing existing SL resins for manufacturing multiple material mechanically and electrically functional models as well as hydrogels, biocompatible materials, and bioactive agents for a variety of biofunctional, implantable tissue engineering applications including nerve regeneration and guided angiogenesis.

null

['Choi, Jae-Won', 'MacDonald, Eric', 'Wicker, Ryan']

2021-09-29T20:12:08Z

2009-09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88210', 'http://dx.doi.org/10.26153/tsw/15151']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['microstereolithography (µSL)', 'multi-material fabrication']

Multiple Material Microstereolithography

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ef014224-446f-4342-ab0d-d1b597ef4ddd/download

University of Texas at Austin

We have previously described the development of a µSL system using a Digital Micromirror Device (DMDTM) for dynamic pattern generation and an ultraviolet (UV) lamp filtered at 365 nm for crosslinking the photoreactive polymer solution. The µSL system was designed with x-y resolution of ~2 µm and a vertical (z) resolution of ~1 µm (with practical limitations on vertical resolution of ~30 µm resulting from the current laboratory setup). This µSL system is capable of producing real three-dimensional (3D) microstructures, which can be used in micro-fluidics, tissue engineering, and various functional micro-systems. As has been explored and described in µSL, many benefits will potentially be derived from producing multiple material microstructures in µSL. One particular application area of interest is in producing multiple material micro-scaffolds for tissue engineering. In this work, a method for multiple material µSL fabrication was developed using a syringe pump system to add material to a small, removable vat designed for the µSL system. Multiple material fabrication was accomplished by manually removing the vat and draining the current material, rinsing the vat, placing the vat back into the system, and dispensing a prescribed volume in the vat using the syringe pump. Layer thicknesses less than ~30 µm were achieved using this process. To demonstrate this system, several multiple material microstructures were produced, and we believe multi-material µSL represents a promising technology for producing functional microstructures with composite materials.

null

['Snarr, Scott E.', 'Najera, Andres', 'Beaman, Joseph Jr.', 'Haas, Derek']

2021-12-07T18:30:25Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90750', 'http://dx.doi.org/10.26153/tsw/17669']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['mutliple-material powder bed fusion', 'machine development', 'nozzle-based powder deposition', 'cross-contamination', 'design of experiments']

Multiple-Material Powder Bed Fusion Machine Development: Reducing Cross-Contamination between Materials

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0295547c-bf90-4cef-b82a-8174e719c51a/download

University of Texas at Austin

Powder bed fusion is an additive manufacturing technology capable of producing fully dense, high strength parts with complex geometries. However, it is currently only able to fabricate parts comprised of a single material. Multiple-material capabilities would allow for an added level of design complexity and the matching of material properties to the functional requirements of a part. In order to achieve this, a full redesign of the current powder deposition system is required. Previous attempts to implement multiple-material powder deposition systems encountered issues with controlling the dimensional accuracy in the build direction and cross-contamination between materials. This research integrates an angled blade leveling mechanism along with a nozzle-based powder deposition system to solve these problems. A design of experiments was run to identify significant leveling parameters and to quantify material cross-contamination. A deposition and leveling system that creates a uniform height multiple-material powder bed with no significant cross-contamination of materials is demonstrated.

null

['Meisel, Nicholas A.', 'Gaynor, Andrew', 'Williams, Christopher B.', 'Guest, James K.']

2021-10-12T18:48:06Z

2013

Mechanical Engineering

null

['https://hdl.handle.net/2152/88717', 'http://dx.doi.org/10.26153/tsw/15651']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['topology optimization', 'PolyJet', '3D printing', 'multiple materials', 'compliant mechanisms', 'material jetting']

Multiple-Material Topology Optimization of Compliant Mechanisms Created via Polyjet 3D Printing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/097f6036-ff64-454d-a15a-cb5524dacf6f/download

University of Texas at Austin

Compliant mechanisms are able to transfer motion, force, and energy using a monolithic structure without discrete hinge elements. The geometric design freedoms and multi-material capability offered by the PolyJet 3D printing process enables the fabrication of compliant mechanisms with optimized topology. The inclusion of multiple materials in the topology optimization process has the potential to eliminate the narrow, weak, hinge-like sections that are often present in single-material compliant mechanisms. In this paper, the authors propose a design and fabrication process for the realization of 3-phase, multiple-material compliant mechanisms. The process is tested on a 2D compliant force inverter. Experimental and theoretical performance of the resulting 3-phase inverter is compared against a standard 2-phase design.

null

['Arrieta, Edel', 'Mireles, Jorge', 'Stewart, Calvin', 'Carrasco, Cesar', 'Wicker, Ryan B.']

2021-11-04T19:14:02Z

2017

Mechanical Engineering

null

['https://hdl.handle.net/2152/90006', 'http://dx.doi.org/10.26153/16927']

eng

2017 International Solid Freeform Fabrication Symposium

Open

['cellular solids', 'unit-cell', 'EBM', 'Ti-6Al-4V', 'digital image correlation', 'microstructure']

Multiscale Analysis of Cellular Solids Fabricated by EBM

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5711d80f-e0d5-4621-ac8e-112109d36d8f/download

University of Texas at Austin

Additive Manufacturing technologies such as Electron Beam Melting are empowering individuals to develop novelty materials by introducing hierarchical levels into solids. Features from the introduced architectures and the manufacturing technology grant these metamaterials with mechanical performances not commonly seen in standard solids. Thus, the response of cellular metals can now be manipulated. In general, the reported research on lattices focuses on very specific topics such as microstructure, geometry and orientation, giving the impression of isolated knowledge. However, the response of these metamaterials is the result of a complex multiscale interaction between these and other factors ranging from the microstructure of the constitutive solid, up to the cell topology. Intended as a one-stop introductory document for a new branch of material designers, the major factors affecting the response of cellular metals are identified, classified and merged into a multiscale discussion supported with evidence from a series of experiments including ASTM standard tests of EBM Ti-6Al-4V standard and lattice specimens, accompanied by failure analysis. The testing features digital image correlation (DIC) for measuring deformations, strain fields, as well as Poisson and shear effects, becoming a critical tool for the advanced characterization of specimens, especially those with complex geometries that normally would require specific instrumentation. Among these multiple determinants; microstructure, manufacturing orientation, manufacturing process, Maxwell’s stability criterion, and other geometrical features are discussed for the comprehensive understanding of two lattice designs presented herein. Lastly, Illustrative examples of how the stress-strain curves are helpful in diagnosing design features to start reverse engineering processes, and a summary of the determinants effects are included.

null

['Seepersad, Carolyn Conner', 'Shahan, David', 'Madhavan, Kaarthic']

2020-03-10T14:23:29Z

2007

Mechanical Engineering

null

['https://hdl.handle.net/2152/80209', 'http://dx.doi.org/10.26153/tsw/7228']

eng

2007 International Solid Freeform Fabrication Symposium

Open

solid freeform fabrication

Multiscale Design for Solid Freeform Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/dbb183e4-0a78-40e1-816d-d4c6c34c19bf/download

null

One of the advantages of solid freeform fabrication is the ability to fabricate complex structures on multiple scales, from the macroscale features of an overall part to the mesoscale topology of its internal architecture and even the microstructure or composition of the constituent material. This manufacturing freedom poses the challenge of designing across these scales, especially when a part with designed mesostructure is part of a larger system with changing requirements that propagate across scales. A setbased multiscale design method is presented for coordinating design across scales and reducing iterative redesign of SFF parts and their mesostructures. The method is applied to design a miniature unmanned aerial vehicle system. The system is decomposed into disciplinary subsystems and constituent parts, including wings with honeycomb mesostructures that are topologically tailored for stiffness and strength and fabricated with selective laser sintering. The application illustrates how the design of freeform parts can be coordinated more efficiently with the design of parent systems.

null

['Morris, C.', 'Debeau, D.', 'Dressler, A.', 'Seepersad, C.C.']

2021-11-03T22:36:10Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89952

eng

2017 International Solid Freeform Fabrication Symposium

Open

['operating parameters', 'multisystem model', 'optimization', 'solar sintering system']

Multisystem Modeling and Optimization of Solar Sintering System

Conference paper

https://repositories.lib.utexas.edu//bitstreams/403609b6-fe09-492a-92e7-7ad494a7f597/download

University of Texas at Austin

In developing countries, the production of building materials such as tile and brick, require large amounts of non-renewable energy and/or time to produce. Previous work has shown that solar sintering machines are capable of producing ceramic parts in a viable amount of time using only solar energy. The systems focus sunlight on a bed of sand where the intensity is sufficient for sintering. Then by moving the sand bed, parts of complex geometry are formed. This study aims to identify optimal operating parameters for the solar sintering system by solving a multi-objective, multisystem model. The subsystems considered are the dynamics of the sand bed, optics of focusing sunlight, and heating of the sand bed. To reduce the computational expense, a Kriging surrogate model was employed to model the heating of the sand bed. Finally by performing a tradeoff analysis of production time and part quality, candidate operating parameters were identified.

null

['Nath, P.', 'Hu, Z.', 'Mahadevan, S.']

2021-11-02T20:38:05Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89891

eng

2017 International Solid Freeform Fabrication Symposium

Open

['uncertainty quantification', 'additive manufacturing', 'multi-level', 'simulation']

Mutli-Level Uncertainty Quantification in Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b9e55226-ee62-4dd4-851a-610a0d6ddecd/download

University of Texas at Austin

Quantifying the uncertainty in additive manufacturing (AM) process plays an important role in the quality control of additively manufactured products. This work presents an uncertainty quantification (UQ) framework to quantify the uncertainty of material microstructure due to multiple uncertainty (aleatory and epistemic) sources present in the AM simulation process. A multi-scale, multi-physics simulation model is first developed to simulate the melting and solidification processes. The melt pool profile obtained from macro-scale finite element analysis is coupled with a micro-scale cellular automata model to predict the microstructure evolution during solidification. Based on the simulation model, various sources of uncertainty are aggregated to quantify the uncertainty in the grain size distribution of the microstructure. The contributions of the various sources of uncertainty to the uncertainty of microstructure grain size distribution are analyzed using variance-based global sensitivity analysis. The results show that the proposed approach can effectively perform UQ of the AM process and the uncertainty in the grain size distribution is mainly affected by material properties and grain growth parameters.

null

['Behera, Dipankar', 'Roy, Nilabh K.', 'Foong, Chee S.', 'Cullinan, Michael']

2021-11-16T15:19:04Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90310', 'http://dx.doi.org/10.26153/tsw/17231']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['powder bed deposition', 'slot-die coating', 'nanoparticle', 'microscale selective laser sintering', 'µ-SLS']

Nanoparticle Bed Deposition by Slot Die Coating for Microscale Selective Laser Sintering Applications

Conference paper

https://repositories.lib.utexas.edu//bitstreams/74545fbd-0ffc-4ec7-a4ce-87523eb45b97/download

University of Texas at Austin

The minimum feature size in most commercially available metal additive manufacturing (AM) processes is limited to ~100 microns which poses a fundamental challenge in fabricating complex 3D micro-components. The authors have developed a microscale selective laser sintering (µ-SLS) process with the goal of fabricating these microproducts with 1µm minimum feature size resolution. To achieve near-net shaped sintered features, the powder bed layer should not be more than one micron thick. This paper presents the development and testing of a powder bed deposition mechanism using a slot-die coater. Metallic nanoparticles uniformly dispersed in a solvent were used in this study. A viscocapillary coating model was used to predict the wet thickness of the powder bed based on the coating gap. Experimental results revealed that uniform sub-micron layer thicknesses were achieved by optimizing the process parameters such as flow rate, coating speed, coating gap, and die gap. The novel approach discussed in this paper enables the implementation of a robust coating mechanism for high throughput AM.

null

['Roth, J.-P.', 'Sulak, I.', 'Chlup, Z.', 'Fischer-Buhner, J.', 'Krupp, U.', 'Jahns, K.']

2024-03-26T16:40:48Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124365', 'https://doi.org/10.26153/tsw/50973']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['NiCu', 'Alloy 400', 'nanoparticle', 'laser powder bed fusion', 'additive manufacturing']

NANOPARTICLE-MODIFICATION OF NICU-BASED ALLOY 400 FOR LASER POWDER BED FUSION

Conference paper

https://repositories.lib.utexas.edu//bitstreams/73c6858b-e536-4e95-b001-c250f94cb225/download

University of Texas at Austin

NiCu-based Alloy 400 is a material being frequently used in corrosive environments wherefore it is applied in several industries like the maritime sector or chemical processing [1]. Numerous functional parts made of this alloy, like heat exchangers or liquid-carrying tubes for instance, may withstand harsh environments to a certain extend but still, at high temperatures and especially in carbon-rich atmospheres, component failure occurs due to poor metal dusting and creep resistance [2–5]. Reinforcing the base alloy system with nanoparticles using gas atomization and subsequent laser powder bed fusion (LPBF) can counteract such material failure [6]. Hence, in this work, titanium was added to Alloy 400 and atomized under nitrogen atmosphere in order to cause TiN nanoparticle formation in the microstructure of printed components.

null

['Sandoval, J. H.', 'Ochoa, L.', 'Hernandez, A.', 'Lozoya, O.', 'Soto, K. F.', 'Murr, L. E.', 'Wicker, R. B.']

2020-02-27T19:07:18Z

8/3/05

Mechanical Engineering

null

['https://hdl.handle.net/2152/80091', 'http://dx.doi.org/10.26153/tsw/7112']

eng

2005 International Solid Freeform Fabrication Symposium

Open

rapid prototyping

Nanotailoring Stereolithography Resins for Unique Applications using Carbon Nanotubes

Conference paper

https://repositories.lib.utexas.edu//bitstreams/dc9390d8-74be-490a-ad26-b4f9f9b77606/download

null

Nanostructured materials and exploiting their properties in stereolithography (SL) may open new markets for unique rapidly manufactured functional devices. Controlled amounts of multiwalled carbon nanotubes (MWCNTs) were successfully dispersed in SL epoxy-based resins and complex three-dimensional (3D) parts were successfully fabricated by means of a multi-material SL setup. The effect of the nanosized filler was evaluated using mechanical testing. Small dispersions of MWCNTs resulted in significant effects on the physical properties of the polymerized resin. A MWCNT concentration of .05 wt% (w/v) in DSM Somos® WaterShed™ 11120 resin increased the ultimate tensile stress and fracture stress an average of 17% and 37%, respectively. Electron microscopy was used to examine the morphology of the nanocomposite and results showed affinity between the MWCNTs and SL resin and identified buckled nanotubes that illustrated strong interfacial bonding. These improved physical properties may provide opportunities for using nanocomposite SL resins in end-use applications. Varying types and concentrations of nanomaterials can be used to tailor existing SL resins for particular applications.

null

['Roberts, Christopher E.', 'Ledbetter, Frank', 'Jones, Jennifer M.', 'Courtright, Zach', 'Blanchard, Alexander']

2024-03-26T23:14:06Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124445', 'https://doi.org/10.26153/tsw/51053']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['NASA', 'in-space manufacturing', 'metal', 'additive manufacturing']

NASA Technology Maturation Plan for In-space Manufacturing of Metals

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a06d9e21-bc02-4c97-87b9-e0b073c9d1d8/download

University of Texas at Austin

As the International Space Station’s (ISS) life approaches its end, NASA intends to travel back to the Moon and establish a sustainable presence, paving a pathway towards Mars. A fundamental shift in the current logistics strategy is required to support extended missions. Ondemand manufacturing enables reduced operational cost and increased long term sustainability providing a pathway towards reducing NASA’s logistics burden. The In-Space Manufacturing (ISM) portfolio at Marshall Space Flight Center is developing additive polymers, metals, and electronics manufacturing technologies to enable a sustainable presence on the Moon and enable long-duration transit missions. Manufacturing systems for in-space applications must meet a unique set of constraints requiring a maturation path independent from processes targeted for terrestrial use. In May 2023, the On Demand Manufacturing of Metals (ODMM) project, part of the ISM portfolio funded through the Game Changing Development (GCD) program office, was canceled; however, prior to cancelation, the engineering team developed a technology maturation plan for in-space manufacturing of metallic components. The status of ODMM at closeout and an overview of the technology maturation plan for ODMM are discussed.

null

['Correa, D.M.', 'Klatt, T.D.', 'Cortes, S.A.', 'Haberman, M.R.', 'Kovar, D.', 'Seepersad, C.C.']

2021-10-13T20:55:34Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88783', 'http://dx.doi.org/10.26153/tsw/15717']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['negative stiffness honeycomb', 'negative stiffness', 'external load', 'recoverable shock', 'laser sintering']

Negative Stiffness Honeycombs for Recoverable Shock Isolation

Conference paper

https://repositories.lib.utexas.edu//bitstreams/41f305e1-0e30-4f72-b4c0-8e27a00e3e45/download

University of Texas at Austin

Negative stiffness honeycomb materials are comprised of unit cells that exhibit negative stiffness or snap-through-like behavior. Under an external load of small magnitude, a negative stiffness honeycomb exhibits large effective elastic modulus, equivalent to those of other standard honeycomb topologies. When the external load reaches a predetermined threshold, the negative stiffness cells begin to transition from one buckled shape to another, thereby absorbing mechanical energy and mechanically isolating the underlying structure. When the external load is released, the honeycomb returns to its original topology in a fully recoverable way. In this paper, theoretical and experimental behavior of negative stiffness honeycombs is explored, based on FEA modeling and experimental evaluation of laser sintered specimens. Additive manufacturing enables fabrication of these complex honeycombs in regular or conformal patterns. Example applications are also discussed.

null

Gervasi, Vito R.

2018-11-29T20:16:35Z

1997

Mechanical Engineering

doi:10.15781/T28P5VW1T

http://hdl.handle.net/2152/70337

eng

1997 International Solid Freeform Fabrication Symposium

Open

['SFF', 'SLA']

Net Shape Composites Using SLA Tetracast Patterns

Conference paper

https://repositories.lib.utexas.edu//bitstreams/448e9380-e38e-4e0b-8d5a-f8c2ada024ab/download

null

Net-shape composites have been a focus of Solid Freeform Fabrication (SFF) for a number of years. A new method to achieve net-shape composites uses hollow Stereolithography (SLA) TetraCast* patterns. The TetraCast* pattern is injected with a filler material consisting of a matrix (typically epoxy) and reinforcement fibers, flakes, andlor particles. Upon solidification ofthe injected matrix, the net-shape composite is achieved. Net-shape composites are ideal for custom manufacturing due to the virtually limitless geometry capabilities of SLA. Areas such as aerospace, medical, manufacturing, and others could someday benefit from this process. Research to date has shown this composite structure to follow the "rule ofmixtures." It has also been shown that heat-deflection, elasticmodulus, and tensile-strength can be enhanced andlor predicted in the composite material. Several areas of continuing research include: viscosity limitations, stair-step notch reduction, reinforcement combinations, shrinkage prediction, cooling methods, SLA skin removal, nextgeneration TetraCast* structures, wear-resistant coatings, process automation, and TetraCast* pattern fill methods.

null

['Klosterman, Don', 'Chartoff, Richard', 'Osborne, Nora', 'Graves, George', 'Lightman, Allan', 'Bezeredi, Akos']

2019-03-01T17:45:27Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73522', 'http://dx.doi.org/10.26153/tsw/672']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['LOM', 'Lamination']

Net Shape Fabrication of SiC and SiC/SiC Components Using Laminated Object Manufacturing (LaM): Overall Process Flowchart

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ddfa736b-92a8-400d-a7da-e26ccf738687/download

null

['Manzur, Tariq', 'Roychoudhuri, Chandra', 'Dua, Puneit', 'Hossain, Fahmida', 'Marcus, Harris']

2018-11-28T20:57:14Z

1997

Mechanical Engineering

doi:10.15781/T2FF3MK37

http://hdl.handle.net/2152/70330

eng

1997 International Solid Freeform Fabrication Symposium

Open

['desk-top manufacturing', 'diode laser']

Net shape Functional Parts Using Diode Laser

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a9569352-4731-412e-862e-44d2d9c396ea/download

null

Manufacturing processes, such as cutting, drilling, soldering, marking, forming 3Dsintered parts from metal powders and laser vapor deposition, are now well established practices using matured high power lasers like Nd:YAG, C02 and Excimer lasers(l). These lasers are bulky, inefficient and expensive. Semiconductor diode lasers, if wavelength is not a disadvantage, hold the potential of creating a major cost/convenience breakthrough in these and other new manufacturing processes such as growing integrated opto-electronics devices etc. They have the potential to initiate a mini industrial revolution because they are compact, have high wall-plug efficiency (50%) and above all, they can be mass produced (like computer chips). It is important to note that almost all laser material processing can be carried out ifthe intensity available can cover the range from 103 to 107 W/cm2 . Fortunately, microscopic as they may be, even low power diode lasers emit reliably at 106 W/cm2 . The hurdle that needs to be solved is coupling energy from a large number of diodes to obtain high total power without losing much oftheir inherent brightness and yet keep the system cost low. Price of high power laser diodes have already come down dramatically over the last five years; further reduction is expected as the volume market keeps increasing rapidly. Current commercial devices are mostly oftwo types: (1) fiber coupled arrays and (2) two-dimensional stacked arrays. We are using both types. We believe, the ultimate high brightness and high total power at low cost will be achieved by 2D array ofbroad area surface emitting lasers. We will present the results of our various activities using 30W (980 nm, spot size - 600 ~m), 10 W (860 nm, spot size - 50 ~m) and 60 W (810 nm, spot size - 700 ~m) fiber-coupled cw diode laser and 50 W (930 nm spot size -700 ~m) free space diode lasers on: (1) fabricating 3D SLS parts directly from metal/ceramic powders using CAD/CAM design, (2) laser assisted selective area vapor phase deposition of amorphous SiC and ShN4-rod, (3) Pb and Ag soldering ofsimple electronic parts, (4) surface hardening ofstainless steel ribbon. INTRODUCT

null

['Marin, Nena', 'Crawford, Richard H.']

2018-11-08T15:52:03Z

1995

Mechanical Engineering

doi:10.15781/T2XW48G10

http://hdl.handle.net/2152/69895

eng

1995 International Solid Freeform Fabrication Symposium

Open

['SLS', 'CT', '3D CT reconstructions']

A Neural Network Architecture to Identify the Bone Tissue for Solid Freeform Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e2742f97-0b88-4ee0-b118-ba52c6de35e0/download

null

Computed tomography produces sets of tomograms for medical interpretation. Typical interpretation consists of imaging and simple observation on a 2D display screen, so that feature extraction and tissue differentiation is based primarily on human expertise. Solid freeform fabrication offers the promise of fabrication of prostheses based on actual patient anatomy. Use of CT data for this purpose requires automated interpretation. This paper presents a system architecture based on neural networks for the segmentation and classification of tissues of interest in tomograms. This approach produces a quantitative recovery of the available information by applying a feed-forward neural net trained with the back-propagation algorithm. The neural network architecture selected was tested on fabricated CT image matrices of the lower extremity.

null

['Hayasi, Mohammad', 'Asiabanpour, Bahram']

2021-10-04T21:47:08Z

8/17/11

Mechanical Engineering

null

['https://hdl.handle.net/2152/88359', 'http://dx.doi.org/10.26153/tsw/15298']

eng

2011 International Solid Freeform Fabrication Symposium

Open

['adaptive slicing', 'design-by-feature', 'fully dense freeform fabrication', 'FDFF']

A New Adaptive Slicing Approach for the Fully Dense Freeform Fabrication (FDFF) Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/500ca05a-2e82-4265-b1f1-de9b460a72ed/download

University of Texas at Austin

FDFF is a process based on thin line cutting processes, variable thickness layering, slicing in different orientations, and bulk layer attachment. The combination of these capabilities enables the production of good quality complex parts from practically any material at a very fast pace. As for rapid prototypes fabricated by the FDFF process, it is certainly possible to employ adaptive slicing technique due to the possibility of cutting different metal/non-metal sheet at various thicknesses. This paper proposes a new adaptive slicing method whereby the capability of cutting a 3D solid model at the predefined sheets’ thicknesses is achieved and the geometry of all internal and external features of a part is also investigated to ensure the reduction of part geometry deviation through the seamless curvature detection. Despite most previous works which start slicing a tessellated or direct CAD model at the maximum available thickness, this system commences the process with available minimum thickness by applying a new adaptive method to all pairs of contours at the top and bottom slices of the layer. Autodesk Inventor solid modeler, as a design-by-feature solid modeler, is used for 3D solid modeling. The proposed system is implemented by Visual Basic codes inside Inventor using API functions to access both geometry and topology information of the design-by-feature solid model . This system has been successfully tested on a variety of complex parts containing sophisticated internal and external features.

null

['Darrah, James', 'Wielgus, Martin']

2018-04-10T18:59:09Z

1990

Mechanical Engineering

doi:10.15781/T2XS5K066

http://hdl.handle.net/2152/64248

eng

1990 International Solid Freeform Fabrication Symposium

Open

['SFF', 'machine designer', 'DTM']

A New CAD Model Format For SFF Machines?

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5158e5eb-1da9-4a35-8453-cb5828597c76/download

null

This paper addresses the issue of a standard input data fonnat for Solid Freefonn Fabrication (SFF) machines. Currently implemented approaches do not address the different aspects of Solid Freefonn Fabrication. This paper will state the requirements from the perspective of the SFF machine designer and make recommendations based on these requirements.

null

['Asiabanpour, Bahram', 'Cano, Robert', 'VanWagner, Lane', 'McCormick, Thomas', 'Wasik, Farhana']

2020-02-20T20:08:42Z

8/17/05

Mechanical Engineering

null

https://hdl.handle.net/2152/80047

eng

2005 International Solid Freeform Fabrication Symposium

Open

['Selective Inhibition of Sintering', 'Waste saving', 'Heater Design']

New Design for Conserving Polymer Powder for the SIS Rapid Prototyping Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/481b142f-c24f-4c7e-80da-243e38f74f33/download

null

Selective Inhibition of Sintering (SIS) is a Rapid Prototyping process that makes parts in a layerbased method by using polymer powders. Current SIS machines accomplish this layer-based method by heating a fixed area of polymer powder. The current process is an area of concern because the entire fixed area of each layer is cured, resulting in large amounts of polymer powder being wasted. This paper explains the design of an automated, mechanical system that will mask off areas of polymer powder with heat-resistant fingers, allowing for the adjustment of the heated area in order to cure minimal amounts of polymer powder at each layer. Test results of a prototype model showed significant reduction in polymer powder usage.

null

['Thissell, W. Richards', 'Marcus, H.L.']

2018-10-03T16:42:26Z

1994

Mechanical Engineering

doi:10.15781/T2ZS2KZ4Z

http://hdl.handle.net/2152/68662

eng

1994 International Solid Freeform Fabrication Symposium

Open

['Selected area laser deposition', '3D printing', 'solid freeform fabrication']

New Developments in Processing and Control of Selected Area Laser Deposition of Carbon

Conference paper

https://repositories.lib.utexas.edu//bitstreams/353ad7e0-ab34-4444-8214-ef9728b9bcef/download

null

Selected area laser deposition (SALD) has been used to deposit carbon from methane, hydrogen, oxygen, and argon mixtures using a third generation deposition system. The effect of two laser scanning hardware/software designs on the development of morphological instability in the resulting deposit is compared. One method uses programmed I/O using the main process control CPU to calculate and download beam position and desired laser power. Another method is presented which uses dedicated direct memory access (DMA) controllers and a dedicated counter/timer to download the required information. Its improvements to the process include better coordination between laser power and beam speed resulting in an improved beam power delivery uniformity and an improved ability to utilize one CPU for control of more of the SALD process variables.

null

['Shuttleworth, M.P.', 'Esfahani, M.N.', 'Marques-Hueso, J.', 'Jones, T.D.A.', 'Ryspayeva, A.', 'Desmulliez, M.P.Y.', 'Harris, R.A.', 'Kay, R.W.']

2021-11-09T15:48:32Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90101', 'http://dx.doi.org/10.26153/tsw/17022']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['co-fabrication', 'flex-rigid electronics', 'electronic circuitry', 'new manufacturing', 'additive manufacturing']

A New Digitally Driven Process for the Fabrication of Integrated Flex-Rigid Electronics

Conference paper

https://repositories.lib.utexas.edu//bitstreams/111e94e0-5616-4a6e-bd2f-63865f64c855/download

University of Texas at Austin

Conventionally, flexible and rigid electronics are produced separately using mask-based lithography techniques thus requiring connectors to join circuits together introducing potential failure modes and additional assembly. This work demonstrates a new manufacturing approach which overcomes this limitation by allowing the co-fabrication of both flex and rigid electronic circuitry within the same part. This is achieved by hybridizing polyetherimide fused filament fabrication with selective photosynthesis of silver nanoparticles and copper electroless plating. The performance and reliability of this approach has been experimentally validated via manufacturing and testing positional sensors. By printing thin layers (< 50 µm), polyetherimide exhibits a high flexibility with minimal degradation from fatigue. Where part thicknesses exceed 180 µm, components start to exhibit rigid properties. A combination of various layer thicknesses allows rigid-flex substrates to be produced, with secondary processing to deposit the circuitry. Positional sensors with metalized feature sizes down to 300 µm have been fabricated that when deflected demonstrate a repeatable 1.4 Ω resistance change for 43,500 cycles.

null

['Zeng, Kai', 'Pal, Deepankar', 'Patil, Nachiket', 'Stucker, Brent']

2021-10-11T21:21:36Z

2013

Mechanical Engineering

null

['https://hdl.handle.net/2152/88647', 'http://dx.doi.org/10.26153/tsw/15581']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['Selective Laser Melting', 'temperature evolution', 'dynamic moving mesh method', 'mesh method', 'computational enhancements', 'fine-scale solution']

A New Dynamic Mesh Method Applied to the Simulation of Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a9ff09d1-d590-4de0-932b-35a69af0bc6f/download

University of Texas at Austin

The process of Selective Laser Melting (SLM) involves the moving of a laser beam across a powder bed to melt material layer by layer. From the standpoint of modeling, this simple procedure is complicated to capture accurately. SLM involves very high laser intensity values, on the order of 1010 W/m2 and a Heat Affected Zone (HAZ) that is orders of magnitude less than the dimensions of the platform. Many computational models have been developed to study temperature evolution in SLM, but most of these models only simulate a small part of the problem with a fine mesh or the entire problem using a coarse mesh to avoid the computational burdens of meshing the full problem with a fine mesh. In order to accurately capture the details of temperature evolution anywhere in a full-sized part located anywhere in the build platform, in an efficient manner, a new dynamic moving mesh method has been developed and implemented in both ANSYS and in a unique Matlab code. This dynamic mesh has been shown to provide significant computational enhancements over other solution methodologies, while enabling fine-scale solutions anywhere in the domain space. A detailed comparison between various ways of solving the SLM problem has been carried out to compare modeling approaches.

null

['Qiu, Dan', 'Langrana, Noshir A.']

2019-09-23T16:47:15Z

2000

Mechanical Engineering

null

['https://hdl.handle.net/2152/75966', 'http://dx.doi.org/10.26153/tsw/3065']

eng

2000 International Solid Freeform Fabrication Symposium

Open

Analysis

A New Feature in an Extrusion Based LM Process – Adaptive Roadwidth 399

Conference paper

https://repositories.lib.utexas.edu//bitstreams/43332397-2b37-4985-bb9d-384eb06ba804/download

null

For extrusion based LM processes, a computational based adaptive roadwidth algorithm have been developed which further reduces (if not eliminate) all voids and defects. Toolpath equations are written in terms of roadwidth, vector path offset, subperimeter offset, and vector angles. The program computes all contours and vector paths to fill a layer, the location and size of all voids/defects, and makes comparison with the acceptable void limits. Based on this information, the adaptive roadwidth for the vector paths are then created to minimize the voids and defects. This new feature is added to the existing in-house multi-material LM CAD software.

null

['Rodriguez, Nicholas', 'Crawford, Richard']

2021-11-08T23:04:14Z

2017

Mechanical Engineering

null

['https://hdl.handle.net/2152/90070', 'http://dx.doi.org/10.26153/tsw/16991']

eng

2017 International Solid Freeform Fabrication Symposium

Open

['3D printed parts', 'high strength', 'ductile', 'filament deposition', 'fused deposition modeling', '3D printer', '3D printing']

New Filament Deposition Technique for High Strength, Ductile 3D Printed Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/649ba7ff-0635-41a6-a852-8dcaa0e0b8b8/download

University of Texas at Austin

This paper proposes a method to use an off-the-shelf commercial Fused Deposition Modeling (FDM) 3D printer with minimal modifications to manufacture higher strength parts that fail in a ductile rather than brittle manner. A novel scan pattern designed to increase interlayer adhesion in FDM parts is modeled and tested to determine its effect on mechanical properties of printed ABS parts. Results from three-point bend testing indicate a significant increase in part strength and elongation at break when using the proposed scan pattern compared to parts manufactured using a traditional scan pattern.

null

['Patil, Nachiket', 'Pal, Deepankar', 'Stucker, Brent']

2021-10-11T21:18:32Z

2013

Mechanical Engineering

null

['https://hdl.handle.net/2152/88645', 'http://dx.doi.org/10.26153/tsw/15579']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'Selective Laser Melting', 'powder bed fusion', 'dimensional reduction', 'phenomenological multi-scale simulation', 'finite element analysis', 'Eigen modes', 'mask projection']

A New Finite Element Solver using Numerical Eigen Modes for Fast Simulation of Additive Manufacturing Processes

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5c00a3ed-cd95-4e47-891a-773d6bf51d9a/download

University of Texas at Austin

A new efficient numerical technique has been formulated for dimensional reduction and phenomenological multi-scale simulation of additive manufacturing processes using finite element analysis. This technique is demonstrated using prismatic build volumes to represent the Selective Laser Melting powder bed fusion additive manufacturing process. The Eigen modes determined as an outcome of implementation of this technique will help to reduce the time necessary for optimization of process parameters and closed loop control. In addition to thermal simulations of the Selective Laser Melting process, this technique is also applicable to the simulation of lattice structures, layered materials such as ultrasonically consolidated laminates, thin walled coatings and development of high fidelity beam and plate theories for parts made using additive manufacturing processes. A future integration of this method with analytical Eigen wavelets will provide infinite support compared to finite support provided by directional polynomial shape functions currently used for implementation of finite element strategies. The present Eigen modes will be also useful in analysis and optimization of mask projection based additive manufacturing processes.

null

['Yen, H. C.', 'Chiu, M. L.', 'Huang, P. H.']

2020-03-11T15:23:01Z

9/10/08

Mechanical Engineering

null

['https://hdl.handle.net/2152/80250', 'http://dx.doi.org/10.26153/tsw/7269']

eng

2008 International Solid Freeform Fabrication Symposium

Open

Ceramic Laser Fusion

A New Layer Casting System for Ceramic Laser Rapid Prototyping Apparatus

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4a794e0d-f107-4043-9e66-7b0ad99e1794/download

null

In the existing Ceramic Laser Fusion system, slurry is fed on the high temperature surface of the green part; therefore, a part of water infiltrates into the green block and vaporizes before the process of layer casting. As a result, the slurry viscosity rises gradually; the quality of the layer surface is not uniform, and the green part density is uneven. The aim of present study is to develop a new layer casting system which can solve the problems mentioned above to obtain a green part with uniform surface quality and density, and to shorten the time-taken of part fabrication. The first part of the paper illustrates the major requirements and parameters of a slurry distributor; the second part describes the integration of the slurry feeding device and layer casting system. The integrated system can feed slurry and cast thin layer simultaneously; consequently, the drawbacks of the existing system can be eliminated and the time-taken of the layer casting can be shortened. A variable-frequency drive (inverter) is used to control the motor speed. The relation between the frequency and the slurry delivery can be included in the process control program to adjust the quantity in accordance with the layer thickness; hence, the waste of the slurry can be reduced.

null

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

2021-09-29T14:37:23Z

9/15/09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88183', 'http://dx.doi.org/10.26153/tsw/15124']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['3D printing', 'new material/binder systems', 'mid-fire to high-fire ceramics']

New Material Systems for 3D Ceramic Printing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b1097313-9be8-4530-bf71-e880560e2a3d/download

University of Texas at Austin

We present new material/binder systems for use in 3D printing hardware for the creation of mid-fire to high-fire ceramics. 3D printing is one of a variety of techniques in which objects are produced by printing binder onto a layer of powder. A brief overview of our process is presented and demonstration works are shown. Several available dry clay bodies were adapted for use in an existing, commercial 3D printer. Details of powder formulation are presented. Experimental results are presented for strain, flexural stress, and porosity for the various clay bodies as a function of firing temperature.

null

['Keller, Nils', 'Ploshikhin, Vasily']

2021-10-18T22:09:34Z

2014

Mechanical Engineering

null

https://hdl.handle.net/2152/89269

eng

2014 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'residual stress', 'residual distortion', 'manufacturing predictions', 'mechanical layer equivalent']

New Method for Fast Predictions on Residual Stress and Distortion of AM Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/64482aa9-945e-4037-a164-afa6c958eb0f/download

University of Texas at Austin

A new multi-scale approach based on the method of finite elements is developed in order to enable much faster predictions of residual stress and distortion for AM parts. The approach includes the calibration of the heat source, the analysis of scanning strategies, the generation of the so-called “mechanical layer equivalent” (MLE) and its integration into a fast structural analysis. The use of MLE determined on the micro-scale and mapped into the largescale structural analysis reduces computational time in comparison with the conventional thermo-mechanical simulations from months to hours while saving the same accuracy of numerical predictions. The new method is realized in newly developed powerful AM software. Simulation results are in a very good agreement with experimental measurements of distortion and residual stress. The potential of the new method to compensate the expected distortion using pre-deformation of parts is demonstrated by numerical experiments of a near-net-shape AM fabrication.

null

['Khodabakhshi, K.', 'Gilbert, M.', 'Dickens, P.', 'Hague, R.', 'Fathi, S.']

2021-09-29T14:47:02Z

2009-09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88186', 'http://dx.doi.org/10.26153/tsw/15127']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['polymerization mixture formulation', 'jetting process', 'polyamide 6 parts']

New polymerization-mixture formulation for jetting: An approach to production of polyamide 6 parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/cd0b3f22-ebf7-49ff-a851-3cc3e78a453d/download

University of Texas at Austin

Poor mechanical properties of manufactured parts is one of the main problems in most of the RP and RM processes. This work deals with a study on formulation of new polymerization mixtures with the aim of being used in jetting process. Two different catalyst components were compared in order to shorten the solidification time and improve the final properties of the manufactured part. The feasibility of jetting polymerization mixtures at jetting head temperature was also investigated. Different characterization and visualization methods (i.e. such as DSC, viscometry, TGA, and hot stage optical microscopy) were used to monitor the polymerization progress and manufactured part properties.

null

['Uhlmann, E.', 'Elsner, P.']

2020-02-20T20:30:33Z

2005

Mechanical Engineering

null

https://hdl.handle.net/2152/80050

eng

2005 International Solid Freeform Fabrication Symposium

Open

polymer applications

New Printing Technology for Fully Graduated Material Properties

Conference paper

https://repositories.lib.utexas.edu//bitstreams/263268b9-ec44-423c-b472-96aaa0ebcf30/download

null

['Cevolini, Franco', 'Davis, Stewart', 'Rinland, Sergio']

2021-09-23T22:40:14Z

9/10/08

Mechanical Engineering

null

['https://hdl.handle.net/2152/88042', 'http://dx.doi.org/10.26153/tsw/14983']

eng

2008 International Solid Freeform Fabrication Symposium

Open

['CRP Rapid Casting Method', 'competitive motor sports', 'Epsilon Euskadi eel']

New Rapid Casting Techniques for Competitive Motor Sports

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5cdfe931-3481-4ceb-a923-56a3e98b3285/download

null

Casting components utilizing free form manufacturing techniques to produce investment patterns have in recent years been overshadowed by the promise of Direct Metal machines. Despite this casting vendors continue to work diligently to make the creation of extremely complex components as an almost common place occurrence. This paper examines the work of CRP Technology and its creation of Windform® PS to advance casting techniques and ultimately produce front and rear uprights for the new “Epsilon Euskadi ee1” for competition in American Le Mans Series and 24 hours of Le Mans 2008. Developed and manufactured utilizing the “CRP Rapid Casting Method” these Titanium Rapid Castings highlight the hard and complex work involved in making this extremely difficult task look easy. The process is examined and outlined to help others understand the work involved.

null

['Ventura, Susanna C.', 'Narang, Subhash C.', 'Sharma, Sunity', 'Stotts, John', 'Liu, Chunling', 'Liu, Susan', 'Ho, Lung-Hua', 'Annavajjula, Durga', 'Lombardo, Steven J.', 'Hardy, Anne', 'Mangaudis, Mike', 'Chen, Eric', 'Groseclose, Lance']

2018-11-14T17:52:46Z

1996

Mechanical Engineering

doi:10.15781/T2G15TX0P

http://hdl.handle.net/2152/70252

eng

1996 International Solid Freeform Fabrication Symposium

Open

['CAD/CAM', 'SFF', 'UV curable polymers']

A New SFF Process for Functional Ceramic Components

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6fe955ac-d7cd-48fc-bfd8-23823a2ce6ed/download

null

SRI International in collaboration with Saint-Gobain/Norton Industrial Ceramics Corporation and Allison Engine Company is developing a new SFF process, Direct Photo Shaping, for the fabrication of functional ceramic components. The process is based on the layerby-layer photocuring of ceramic slurries containing monomers curable by visible light. Each layer is photoimaged by a liquid crystal display (LCD) or a digital light processing (DLP) projection system. After binder removal and sintering, the properties of silicon nitride tiles prepared according to the Dire~t Photo Shaping process were found to be comparable to properties of tiles formed by conventional methods.

null

['Rock, Stephen J.', 'Gilman, Charles R.']

2018-10-04T20:02:13Z

1995

Mechanical Engineering

doi:10.15781/T2WM14C85

http://hdl.handle.net/2152/68709

eng

1995 International Solid Freeform Fabrication Symposium

Open

['freeform powder molding', 'SFF', 'prototyping methods']

A New SFF Process for Functional Part Rapid Prototyping and Manufacturing: Freeform Powder Molding

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4b5399f8-388c-4ccf-8523-088f4beeeada/download

null

Freeform Powder Molding l (FPM), a new Solid Freeform Fabrication process capable of directly producing functional parts from a wide range of structural materials, is presently being developed. This paper describes the fundamental process concept currently pending patent and provides early results demonstrating process feasibility. Materials used in process validation experiments include copper, iron, nickel, 304 stainless steel, and titanium. The process has the potential to meet the needs of both Rapid Prototyping and small lot-size manufacturing applications.

null

['Wang, Feng', 'Chen, Ke-Zhang', 'Feng, Xin-An']

2020-02-13T19:54:53Z

8/24/04

Mechanical Engineering

null

['https://hdl.handle.net/2152/79971', 'http://dx.doi.org/10.26153/tsw/6996']

eng

2004 International Solid Freeform Fabrication Symposium

Open

composite materials

Novel Implementations of Plasma Spraying for Fabricating Components Made of a Multiphase Perfect Material

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c8946b11-d459-4135-98da-33d5875c9876/download

null

A component, which has a perfect combination of different materials (including homogeneous materials and different types of heterogeneous materials) in its different portions for a specific application, is considered as the component made of a multiphase perfect material. Based on the requirements for fabricating different types of heterogeneous materials, a hybrid manufacturing process with layered manufacturing, micro-fabrication, and mechanical machining has been developed under the guidance of Axiomatic Design. According to the hybrid process, this paper investigates the related technologies and selects plasma spraying technology to spread materials layer by layer; and further analyzes its key design parameters, improves plasma spraying technology, and presents a novel implementation of this technology.

null

['Slightam, Jonathon E.', 'Gervasi, Vito R.']

2021-10-05T18:45:05Z

8/18/12

Mechanical Engineering

null

['https://hdl.handle.net/2152/88404', 'http://dx.doi.org/10.26153/tsw/15343']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['Additive Manufacturing', 'fluid power components/systems', 'solid state actuators', 'solid state actuator systems', 'Milwaukee School of Engineering']

Novel Integrated Fluid-Power Actuators for Functional End-Use Components and Systems via Selective Laser Sintering Nylon 12

Conference paper

https://repositories.lib.utexas.edu//bitstreams/fda4555e-729d-481a-9994-b6aaf627c052/download

University of Texas at Austin

The Milwaukee School of Engineering (MSOE) and the Additive Manufacturing (AM) community have an interest in expanding applications of AM and broadening market opportunities. Specific areas of interest include robotics and fully functional components/systems. MSOE has developed methods for streamlining the development and implementation of functional fluid power components/systems, such as Magnetic Resonance Imaging (fMRI) robotic surgery systems, rescue robotics, and customized form-fit orthotic and prosthetic devices, all of which have a high power-density and high efficiency with the use of fluid power. MSOE has defined several of these components and devices as solid state actuators (SSA) (single, multi-functional components made of diaphragms, bellows, springs etc.) or solid state actuator systems (SSAS). Prior work has already been done on integrated systems for robotic prototypes to help determine and improve workspaces, thus allowing designers to make practical design changes at a low cost. Implementing AM fluid power devices in industry has also been done, where applications largely include human-machine interaction and biomimetic or continuum robotics. However, most devices are made up of numerous components in assemblies. MSOE has made it possible for mechanisms to be fully functional as built and as a single entity. The implementation and development of SSAs and SSASs are discussed along with practical design considerations of integrated functional fluid power components.

null

['Wang, Z.', 'Zhang, Y.', 'Bernard, A.']

2021-12-06T23:33:18Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90718', 'http://dx.doi.org/10.26153/tsw/17637']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['tool-path', 'constructuve design', 'triply periodic minimal surface', 'knowledge-based system']

A Novel Knowledge-Based Toolpath Constructive Approach for Designing High-Precision Graded Lattice Structures

Conference paper

https://repositories.lib.utexas.edu//bitstreams/662eb205-3ecd-4e08-9b27-836ee615f2d2/download

University of Texas at Austin

Current part-scale lattice design methods cause accuracy loss and manufacturability uncertainty in AM preparation stages. STL model conversion and slicing can lead to loss of shape accuracy and surface quality, while unqualified toolpaths may cause printing failures, e.g. pores or re-melting in the powder-bed fusion process. Moreover, all these steps are time-consuming due to the large model file. To solve these challenges, this paper proposes a novel knowledge-based toolpath constructive design method to generate high-precision graded lattice unit cells with manufacturability. It integrates implicit modeling, variable distance field, direct slicing and fine toolpath configuration to construct qualified toolpaths without any intermediate steps. To save computation time in part-scale lattice design, predefined different types or sizes of graded lattice unit cells are populated and assembled into a given design space directly. Hence, it has big potential to improve industrial application of part-scale porous structures with fine and gradient porous features.

null

['Pogue, Robert T.', 'Chartoff, Richard P.']

2018-12-05T16:46:02Z

1997

Mechanical Engineering

doi:10.15781/T26970J2T

http://hdl.handle.net/2152/71397

eng

1997 International Solid Freeform Fabrication Symposium

Open

['spectroscopy', 'stereolithography']

Novel Liquid Crystal Monomers for Stereolithography: Reaction Rates and Photopolymerization Conversion

Conference paper

https://repositories.lib.utexas.edu//bitstreams/37cfe08d-877d-49ff-9f62-bd4ac8e01d9e/download

null

Liquid crystal (LC) monomers are a novel type ofresin for stereolithography that result in polymers having unique physical and mechanical properties. These monomers consist ofrigid central cores connected to acrylate functional groups by short aliphatic chains. Because ofthe rigid-rod structure ofthe monomer the cross-linked polymer networks formed have high glass transition temperatures (Tg). The high TglS result in particularly high upper-use temperatures for stereolithography parts. This paper reports on photopolymerization reaction rates and monomer conversion for two acrylate monomers measured using reflectance real-time infra-red spectroscopy (RRTIR). The RRTIR method measures the disappearance ofreactive acrylate groups in the monomer as a function oftime while the monomers are being exposed to UV light. For the two new resins, UV irradiation using an argon ion laser gives rapid photopolymerization with acrylate conversion as high as 95 %. Conversion and polymerization rates in these monomers are dependent upon photo-initiator selection and concentration. In addition, the results indicate that conversion increases with increased laser intensity and elevated temperatures.

null

['Schultz, J. W.', 'Ullett, J. S.', 'Chartoff, R. P.', 'Pogue, R.T.']

2018-12-05T16:44:20Z

1997

Mechanical Engineering

doi:10.15781/T2B27QB6K

http://hdl.handle.net/2152/71396

eng

1997 International Solid Freeform Fabrication Symposium

Open

['stereolithography', 'Liquid crystal']

Novel Liquid Crystal Resins for Stereolithography: Mechanical and Physical Properties

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e43de412-60d6-4b2e-bf58-a4a9a45d6616/download

null

This paper considers photocurable liquid crystal (LC) monomers which are a new class of stereolithography resins. These resins form polymers with high upper-use temperatures. The rodlike molecules can be aligned by an external force. When cured in an aligned state, the aligned structure is "locked in" resulting in materials with anisotropic physical and mechanical properties. FTIR spectroscopy, thermo-mechanical analysis (TMA), dynamic mechanical analysis (DMA), and large strain mechanical tests were applied to liquid crystal photo-polymers, both in the green state and after postcure. These measurements showed that the photo-polymerization reaction locked in the molecular order. Elastic modulus in the glassy state, revealed approximately a factor of two difference between the directions parallel and perpendicular to the alignment. Thermal expansion measurements showed an anisotropic linear expansion that was very small, and sometimes negative in the alignment direction. Finally, these resins demonstrated high glass transition temperatures which could be advanced to as high as 150°C by postcuring.

null

['Erler, M.', 'Streek, A.', 'Schulze, C.', 'Exner, H.']

2021-10-12T19:52:33Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88726', 'http://dx.doi.org/10.26153/tsw/15660']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['laser micro sintering', 'micro powder', '3D-measurement', 'in-situ']

Novel Machine and Measurement Concept for Micro Machining by Selective Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f37ae447-91a0-43d4-a417-ef553a653ed8/download

University of Texas at Austin

Laser sintering has been established in solid freeform fabrication to produce individual micro parts and small batches. However, the achievable resolution and accuracy of this technology seems to be not sufficient to meet prospective demands in micro production, i.e. micro system technology, aerospace or innovative medical applications. As a modification of the technology, laser micro sintering (LMS) was developed to overcome this limitation. In general, the results obtained in LMS demonstrated already the high potential of this additive manufacturing process in micro production. The limited dimensions of the micro parts and even the reproducibility, due to the special process requirements regarding the applied powder particles sizes in the µm-ranges, inhibits the implementation as an industrial manufacturing process. Therefore a novel concept of setups, suitable for an industrial demand of selective laser sintering with noticeable higher resolutions has to be proven. As a first, a novel machinery setup for a high resolution selective laser sintering has been studied in this work. To achieve a sufficient repeatability of the sintering process, a new method for in-situ analyzing and measuring is implemented and allows the verification the homogeneity and thickness first: of the deposited powder layers and second: of the resulting sinter structure. As an innovative feature the measurement system has to be applied as an in-situ method for direct process controlling in a future use. Accordingly, the possibility to recognize structural defects during generation of sintered bodies are presented and comparably analyzed by cross sections of the respective specimens.

null

['Xie, Yang', 'Zhang, Haiou', 'Wang, Guilan', 'Zhou, Fei']

2021-10-12T21:28:00Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88744', 'http://dx.doi.org/10.26153/tsw/15678']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['metamorphic rolling mechanism', 'variable wall thickness', 'arc based deposition', 'additive manufacturing', 'net shape components']

A Novel Metamorphic Mechanism for Efficient Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/196d5e8c-d94f-4353-973c-0d04ed9bede4/download

University of Texas at Austin

A novel metamorphic rolling mechanism (MRM) based on genetic evolution synthesis that realized multiway, multiple-DOF and synchronous plastic forming in arc based deposition processing of components with variable wall thickness is proposed in this paper. Topology and mechanical structure of the metamorphic mechanism is presented and D-H equation is derived. Experiments show that firstly efficient manufacturing of components with variable wall thickness can be realized by synchronous rolling in vertical direction. Secondly precision and surface configurations of the components are improved compared with that of freeform deposition manufacturing. The metamorphic mechanism provides possibilities of efficient hybrid manufacturing of near net shape components with variable wall thickness.

null

['Goel, Abhishek', 'Surana, Anupam', 'Choudhury, Asimava Roy']

2021-09-23T21:46:00Z

9/10/08

Mechanical Engineering

null

['https://hdl.handle.net/2152/88029', 'http://dx.doi.org/10.26153/tsw/14970']

eng

2008 International Solid Freeform Fabrication Symposium

Open

['part decomposition', 'Hybrid Rapid Prototyping', 'undercut edges']

A Novel Method for Part Decomposition Based on Undercut Edges for Efficient Hybrid Rapid Prototyping

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3f216e32-b810-4bf7-9665-8ed091965597/download

null

Layered Manufacturing allows physical prototypes of 3D parts to be built directly from their computer models, as a stack of 2D layers. This article proposes to decompose the model to be built into minimum number of layers and then build each layer separately by performing machining operations on a given sheet of metal, using a 3-axis CNC milling machine and adhering the layers, allowing large models to be built in parallel. The decomposition of the model is carried out in such a fashion that it decomposes all the inaccessible regions in the object such as under-cut concave edges. For a given build up direction, the undercut edges, which cause a part to be inaccessible by a tool, are extracted and eliminated in two decomposition steps ensuring that the number of layers are as least as possible, thus minimizing the build time.

null

['Li, Jinghao', 'Luo, Zhibo', 'Guan, Xiaoyi', 'Zhou, Xianglin', 'Brochu, Mathieu', 'Zhao, Yaoyao Fiona']

2021-11-11T16:43:17Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90243', 'http://dx.doi.org/10.26153/tsw/17164']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['microstructure simulation model', 'microstructure', 'invasion model', 'grain growth', 'direct energy deposition', 'DED']

A Novel Microstructure Simulation Model for Direct Energy Deposition Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c0ab1186-c1fa-4ecb-9d2e-ef82582913e3/download

University of Texas at Austin

The microstructure of additive manufacturing parts has unique characteristics. In this paper, a novel microstructure simulation model is proposed in grain level, called "Invasion Model", to simulate the transient competitive grain growth behaviour in direct energy deposition (DED) process. Different from the phase field method, the invasion model does not focus on the exact dendrite geometry immersed in the liquid phase which will usually lead into high computational cost. The key point of the invasion model is its capability to reflect the transient competitive grain growth behavior under the triensent thermal gradient located at the bottom of the melt pool. An ‘invasion factor' is proposed to represent the possibility that one single crystal will invade its adjacent crystals in each time step. This ‘invasion factor' is calculated by the relation between crystallographic orientation and a changing thermal gradient under the help of the grain boundary criterions in competitive grain growth. Furthermore, the shape and the cooling condition of the melt pool are vital to the final microstructure. The geometry of the melt pool is extracted from the temperature history data of finite element and CFD simulation. The melt pool geometry is analyzed quantitively from interpolated temperature history data and inputted into the invasion model. A vertical cross section of DED fabricated Ti-6Al-4V in multiple layers was investigated by the invasion model, and the competitive grain growth behavior is simulated between the crystals with random crystallographic orientations.

null

['Pan, Yayue', 'Patil, Abhishek', 'Zhou, Chi']

2021-10-19T15:44:01Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89304

eng

2014 International Solid Freeform Fabrication Symposium

Open

['multi-material printing', 'metal-polymer composite', 'additive manufacturing', 'electrophotography', 'stereolithography', 'vat photopolymerization']

A Novel Projection Based Electro-Stereolithography (PES) Process for Composite Printing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d0a01ca5-8a77-4cfd-b179-21682cd3c41f/download

University of Texas at Austin

Most current additive manufacturing processes can only process one material in one build. Few of them are able to fabricate multiple materials and composites, with limited choices of materials. In this research, we propose a novel Projection based Electro-Stereolithography (PES) process, which is able to fabricate composites with high resolution and fast speed, and a big range of material choices. The proposed novel additive manufacturing process integrates projection-based stereolithography and electrophotography approaches by using a photoconductive film and digital micro-mirror device (DMD). In PES, a photoconductive film is used to collect charged particles in the regions illuminated by light. More specifically, a laser beam is scanning on the film to create a latent image on the film and then a layer of charged particles is attracted to the illuminated area. A liquid bridge system and a stamping system have been developed to transfer particles from the film to liquid resin precisely. Furthermore, a digital mask is used to pattern the light irradiation of the DMD chip to selectively cure the photopolymer liquid resin and particles of that layer. By transferring particles with designed patterns to the resin in a projection based stereolithography system, we will be able to fabricate composites with various materials at microscopic resolutions very quickly. Challenges in this novel manufacturing process, including transferring of particles and curing control, have been discussed and addressed. The corresponding key parameters of the particles collecting, dropping and curing in the PES system have been identified. A proof-of-concept PES testbed has been developed and a couple of tests have been performed to validate the feasibility of the proposed additive manufacturing approach.

null

['Biester, K.', 'Schwarz, N.', 'Hermsdorf, J.', 'Kaierle, S.']

2024-03-26T16:42:24Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124366', 'https://doi.org/10.26153/tsw/50974']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['LDNA', 'cladding', 'waviness', 'welding strategy', 'high deposition rate']

NOVEL WELDING STRATEGY IN HIGH DEPOSITION RATE LASER-ASSISTED DOUBLE-WIRE WELDING PROCESS WITH NONTRANSFERRED ARC

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4e32f634-0a8f-444d-a5bb-4c4251f28751/download

University of Texas at Austin

Laser-assisted double wire welding with nontransferred arc melts material using an arc between two conveyed wires. Driven by gravity the molten metal drops onto the substrate. A laser beam is oscillated on the melt pool to bond the weld beads to the substrate without undercuts. Claddings at high deposition rates (11.6 kg/h) were performed with 316L on mild steel. The first welding strategy (AAA) is to weld adjacent beads (A) with a varied track spacing of 7 to 9 mm. The second strategy (ABA) consists of beads (A) welded at a distance of 14 to 18 mm from each other, so that a third bead (B) can be deposited in the space between. Claddings with the determined track spacing for AAA of 9 mm and ABA 18 mm were created in order to compare the resulting surface properties. The ABA cladding did not achieve a more uniform surface and less waviness than the AAA cladding.

null

['Liu, Heng', 'Sparks, Todd E.', 'Liou, Frank W.', 'Dietrich, David M.']

2021-10-11T21:29:06Z

8/16/13

Mechanical Engineering

null

['https://hdl.handle.net/2152/88649', 'http://dx.doi.org/10.26153/tsw/15583']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['direct metal deposition', 'thermo-mechanical finite element model', 'finite element model', 'residual stress', 'deformation', 'deposition parameters']

Numerical Analysis of Thermal Stress and Deformation in Multi-Layer Laser Metal Deposition Processes

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b172e910-7708-4f7a-bb16-3ce46c3beed3/download

University of Texas at Austin

Direct metal deposition (DMD) has gained increasing attention in the area of rapid manufacturing and repairing. This process involves extremely high thermal gradients and heat and cooling rate, resulting in residual stresses and distortion. This paper presents a 3D sequentially coupled thermo-mechanical finite element model to predict residual stresses and deformations. The temperature distribution, thermal stress field and geometry deformation across domain are illustrated. The effect of deposition parameters on residual stress and deflections are also explored. A set of validation experiments for mechanical effects were conducted using laser displacement sensor. The comparisons between the simulated and experimental results show good agreement.

null

['Thakar, Yogesh', 'Pan, Heng', 'Liou, Frank']

2020-02-14T16:21:38Z

8/4/04

Mechanical Engineering

null

['https://hdl.handle.net/2152/79992', 'http://dx.doi.org/10.26153/tsw/7017']

eng

2004 International Solid Freeform Fabrication Symposium

Open

Axial powder stream

Numerical and Experimental Analysis of the Powder Flow Streams in the Laser Aided Material Deposition Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c57f489a-066f-4409-aa03-94a1a7aae86a/download

null

Axial powder stream concentration between the nozzle end and the deposition point is an important process parameter in the laser aided material deposition process. The powder concentration is greatly influenced by the nozzle geometry in use. This paper describes the numerical and experimental analysis of this important parameter in relation to the coaxial nozzle. The experiments are performed with the different nozzle geometries to generate various flow patterns of the gravity fed powder in a cold stream. The results of the experimental analysis are compared with the numerical simulation and found justified. These results are used in concluding the significance of important nozzle parameters for various powder concentration modes.

null

['du Plessis, Anton', 'Yadroitsava, Ina', 'Kouprianoff, Dean', 'Yadroitsev, Igor']

2021-11-09T20:28:43Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90158', 'http://dx.doi.org/10.26153/tsw/17079']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['lattice structure', 'porosity', 'Ti6Al4V', 'laser based powder bed fusion', 'microCT']

Numerical and Experimental Study on the Effect of Artificial Porosity in a Lattice Structure Manufactured by Laser Based Powder Bed Fusion

Conference paper

https://repositories.lib.utexas.edu//bitstreams/57f1888f-9634-471d-a86c-06a461808236/download

University of Texas at Austin

Additively manufactured lattice structures are used in various applications due to their unique properties, especially low weight with relatively good strength and stiffness. While lattices have been investigated widely, the effect of manufacturing flaws on the lattice performance was not yet analyzed in detail. One important type of manufacturing flaw which can be relatively easily analyzed numerically and experimentally is unwanted voids or porosity. In this work, using a simple cubic lattice structure as a test case, pores with varying sizes were induced in a single strut and compressive loading simulated. Ti6Al4V ELI (extra low interstitial) lattices produced by laser powder bed fusion, with and without induced pores, were subjected to mechanical compression tests. MicroCT images validated the presence and size of the induced voids in produced samples. The mechanical compression results show that even relatively large pores in individual loadbearing struts do not affect the ultimate compressive strength of these lattices, for these particular lattice shapes studied and for individual large pores.

null

['He, Haiyang', 'Cheng, Bo', 'Schmidt, Kaja', 'Kruse, Claudia', 'Tuffile, Charles']

2021-11-18T17:24:30Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90436', 'http://dx.doi.org/10.26153/tsw/17357']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['polymer dispensing', 'computational fluid dynamics', 'CFD', 'strand', 'process-quality map']

Numerical Investigation of Extrusion-Based Additive Manufacturing for Process Parameter Planning in a Polymer Dispensing System

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4b94a66b-65cc-4bb0-863d-7aecfff682e5/download

University of Texas at Austin

This paper establishes a computational fluid dynamics (CFD) model using ANSYS Fluent for the time-pressure polymer dispensing process. The developed model simulates the process of liquid being applied on a substrate and predicts critical performance indexes, such as strand width and height, of the dispensing system. A mesh sensitivity analysis has been performed to identify the element size for achieving satisfactory accuracy and efficient computation time. The influences of material properties, such as surface tension and viscosity, on the simulation results were investigated. In addition, the effect of flow rate and nozzle translational speed on strand width were studied. The simulation results were validated against experimental measurements, and the model was demonstrated to be effective in predicting the strand width. Based on the simulations, a process map was constructed for process parameter planning and optimization.

null

['Li, Xuxiao', 'Tan, Wenda']

2021-10-26T18:23:19Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89551

eng

2016 International Solid Freeform Fabrication Symposium

Open

['selective laser sintering', 'laser absorption', 'powder bed', 'ray tracing method']

Numerical Investigation of Laser Absorption by Metal Powder Bed in Selective Laser Sintering Processes

Conference paper

https://repositories.lib.utexas.edu//bitstreams/08982495-5c5f-49b8-80ee-0dfcbcfa1d54/download

University of Texas at Austin

Laser absorption by powder bed in selective laser sintering (SLS) processes remains a critical issue to be fully understood. This issue is important for the appropriate selection of processing parameters in practices as well as an accurate definition of the thermal input in numerical modeling. In this work, a ray tracing model is used to study this issue. In parametric studies, the effects of laser parameters and powder bed structures on the laser absorption are investigated. It is found that a top-hat laser produces a more uniform laser absorption within laser heated spots than a Gaussian laser. The absorption distribution generally does not follow an exponential decay; instead, it gradually increases to a “peak” and then decreases along the laser shooting direction. The absorption near the substrate can be enhanced when the powder bed thickness is reduced, which helps to bind the newly deposited layer with its substrate in SLS processes. Finally, using bimodal powder beds can reduce laser penetration and produce more uniform laser absorption in laser heated spots.

null

['Sheth, Sanchita', 'Taylor, Robert M.']

2021-11-03T20:57:25Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89932

eng

2017 International Solid Freeform Fabrication Symposium

Open

['stiffness', 'raster orientation', 'fused deposition modeling', 'numerical investigation']

Numerical Investigation of Stiffness Properties of FDM Parts as a Function of Raster Orientation

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4dfff7ad-f97c-4274-b330-806521302439/download

University of Texas at Austin

This work discusses a numerical investigation of stiffness properties of parts printed using Fused Deposition Modeling (FDM). Small volumes of different raster orientations were modelled and meshed using SIMULIATM (Abaqus). These meshes were exported to a damage prediction software BSAM, which uses a homogenization approach to model interface bond strength between adjacent raster beads. In BSAM, boundary conditions, connectivity and material properties have been specified. This BSAM model was then used to compare stiffness properties at various raster angles. A similar trend in the modulus values was observed from experimental test data. Further this model could be used to specify and predict interface properties for the specimens at various raster angles which could be used to eventually predict strength and fracture.

null

['Jamshidinia, M.', 'Kong, F.', 'Kovacevic, R.']

2021-10-11T22:48:35Z

2013

Mechanical Engineering

null

['https://hdl.handle.net/2152/88674', 'http://dx.doi.org/10.26153/tsw/15608']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['fatigue failure', 'surface roughness', 'fatigue strength factor', 'bio-compatible dental implant', 'Electron Beam Melting® (EBM)']

The Numerical Modeling of Fatigue Properties of a Bio-compatible Dental Implant Produced by Electron Beam Melting® (EBM)

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2568c0bb-6d09-4d1d-b020-c399a3dc61b7/download

University of Texas at Austin

Cyclic load could result in the fatigue failure of a component at stress levels below the yielding stress of material. Therefore, studying the mechanical behaviors of a dental implant structure under cyclic load is required. The numerical modeling of a cyclic load test was performed for a bio-compatible dental implant by using ANSYS® Workbench®. The fatigue test samples, made of Ti-6Al-4V were manufactured by Electron Beam Melting® (EBM) process. An abutment with octahedral lattice structure of 2 mm unit cell size was selected to design the abutment. A sinusoidal wave was used to apply the cyclic load, where the loading ratio was set at 10%. The influences of the loading force and the fatigue strength factor on the fatigue life of the octahedral lattice structure were numerically studied. According to the results, an increase in the loading force was associated with an increase in the maximum equivalent stress developed in the lattice structure. Also, the numerical results showed that applying a load above 441 N resulted in a sharp decrease in the fatigue life of the lattice structure from 107 cycles to 5.5×104 cycles. It was shown that an increase in the fatigue strength factor from 0.81 to 0.87 improved the fatigue life about 100 times. Therefore, improving the surface roughness of the bio-compatible dental implant could be one of the major factors that could increase the implant fatigue resistance and should be considered through the design optimization of the dental implant.

null

['Wu, Maxwell', 'Sammons, Patrick M.', 'Barton, Kira']

2021-11-03T21:24:53Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89936

eng

2017 International Solid Freeform Fabrication Symposium

Open

['electrohydrodynamic jet printing', 'CFD', 'modeling']

Numerical Modeling of High Resolution Electrohydrodynamic Jet Printing Using OpenFOAM

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7c95cb18-6483-495e-837c-4ee54c401e64/download

University of Texas at Austin

Electrohydrodynamic jet (e-jet) printing is a micro-/nano-scale additive manufacturing (AM) method that has emerged in recent years as a process to rival similar technologies such as inkjet printing. By utilizing electrostatic forces to induce fluid flow, e-jet has shown the ability to fabricate high resolution features with a wide variety of materials. Because it is a relatively new AM process, the printing behavior of many different types of inks are not completely understood, as existing knowledge of the process relies almost entirely on empirical methods that can be time intensive and difficult to implement for materials that are hazardous or not readily available. This paper discusses procedures for modeling both the electric and fluid dynamics of the e-jet printing process within OpenFOAM, an open-source computational fluid dynamics (CFD) solver. Further discussion has been provided to show simulations of the process at typical high resolution e-jet printing scales and to present existing limitations of the model.

null

['Comminal, R.', 'Serdeczny, M.P.', 'Pederson, D.B.', 'Spangenberg, J.']

2021-11-15T20:51:13Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90267', 'http://dx.doi.org/10.26153/tsw/17188']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['material deposition', 'contouring precision', 'fused deposition modeling', 'numerical model']

Numerical Modeling of the Material Deposition and Contouring Precision in Fused Deposition Modeling

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a1b1c3e0-5b05-4a91-8ed9-9d94d32690a0/download

University of Texas at Austin

We present a numerical model of the material deposition in fused deposition modeling. The flow of the material extruded from the printing head nozzle is simulated within the computation fluid dynamics (CFD) paradigm. The molten thermoplastic is modeled as an incompressible Newtonian fluid with a free surface. The numerical model provides a prediction of the shape of the printed road. Four deposition strategies are investigated to print a road along a tool path with a 90° turn. The investigated scenarios include the ideal case of an extrusion rate synchronized with the printing speed, as well as the cases of a sharp tool path with a stop-at-turn trajectory, and a smoothed tool path with blended acceleration. The CFD simulation provides a way to optimize the tool path planning and the deposition strategy, in order to improve dimensional accuracy in extrusion-based additive manufacturing.

null