ccm/sff-papers · Datasets at Hugging Face

['Serdeczny, Marcin P.', 'Comminal, Raphaël', 'Pederson, David B.', 'Spangenberg, Jon']

2021-11-15T20:48:44Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90266', 'http://dx.doi.org/10.26153/tsw/17187']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['printing parameters', 'porosity', 'fused deposition modeling']

Numerical Prediction of the Porosity of Parts Fabricated with Fused Deposition Modeling

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4ce2437d-8813-4f22-82b7-44fc8d1ae04a/download

University of Texas at Austin

In this paper, we study the effect of the printing parameters, namely the layer thickness and the strand-to-strand distance, on the porosity of components produced with Fused Deposition Modeling (FDM). The FDM process is based on the extrusion of a melted material through a nozzle, which forms a 3D object, layer by layer from the subsequent deposition of strands. Previous numerical modeling and experimental studies have showed that the cross-section of the strands depends on the printing parameters. Using computational fluid dynamics simulations, we predict the shape of the cross-sections of multiple strands printed next to each other, and we estimate the porosity of the part. The results of this study show that the porosity of the parts produced by FDM can be controlled by adjusting the printing parameters.

null

['Mollah, Tusher', 'Comminal, Raphaël', 'Serdeczny, Marcin P.', 'Pederson, David B.', 'Spangenberg, Jon']

2021-12-07T17:29:35Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90731', 'http://dx.doi.org/10.26153/tsw/17650']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['yield stress', 'layer stability', 'viscoplastic materials', 'multilayer printing', 'numerical modeling']

Numerical Predictions of Bottom Layer Stability in Material Extrusion Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5fbbc11a-4cd4-43aa-8890-17722ae75e73/download

University of Texas at Austin

Robocasting and 3D concrete printing are technologies that belong under the umbrella term material extrusion additive manufacturing. These two free form fabrication methods are used to produce 3D structures/components in materials such as ceramic pastes, thermosets, and concrete. Common for the materials is their viscoplastic behavior during deposition and structural buildup (i.e., increase in yield stress) after deposition. The material’s complex nature makes it a nontrivial task to ensure that printed layers do not deform when depositing additional layers on top. In this paper, we numerically investigate the influence of the yield stress buildup of viscoplastic materials on the stability of the bottom layer during multilayer printing. Specifically, we have developed a computational fluid dynamics model that applies a scalar approach to alter the yield stress. The novel model provides fundamental knowledge on how to design the material’s rheology, so the bottom layer can withstand both the hydrostatic- and extrusion-pressure.

null

['Zhou, X.M.', 'Zhang, H.O.', 'Wang, G.L.', 'Liang, L.Y.', 'Fu, Y.H.', 'Bai, X.W.', 'Wang, X.P.']

2021-10-19T18:15:07Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89315

eng

2014 International Solid Freeform Fabrication Symposium

Open

['arc based additive manufacturing', 'external longitudinal static magnetic field', 'magnetic field', 'numerical simulation']

Numerical Simulation and Experimental Investigation of Arc Based Additive Manufacturing Assisted with External Longitudinal Static Magnetic Field

Conference paper

https://repositories.lib.utexas.edu//bitstreams/dd37dab6-a6c0-4033-95df-d392be1a7d05/download

University of Texas at Austin

This paper proposes a new arc based additive manufacturing method assisted with external longitudinal static magnetic field. An electromagnetic coupling numerical model has been established, which consists of droplet impingement, heat transfer and dynamics of molten pool. Comparing the simulation results between normal deposition and external longitudinal magnetic filed assisted deposition, it shows that the external longitudinal static magnetic field induces the tangential stirring force in molten pool and drives the molten metal moving to the edge of the pool. This can reduce the temperature gradient in forming region. Furthermore, the related comparison experiments of single-bead deposition and multi-beads overlapping deposition are performed, it was found that the tangential stirring force can reduce the height of single-bead as well as increase the width of single-bead. The experimental results are in accordance with the simulation results. The changing of morphology of the bead is beneficial to multi-beads overlapping and capable of improving the surface accuracy for arc based additive manufacturing parts.

null

['Fan, Zhiqiang', 'Jambunathan, Anand', 'Sparks, Todd E.', 'Ruan, Jianzhong', 'Yang, Yu', 'Bao, Yaxin', 'Liou, Frank']

2020-03-02T15:44:28Z

2006

Mechanical Engineering

null

['https://hdl.handle.net/2152/80138', 'http://dx.doi.org/10.26153/tsw/7159']

eng

2006 International Solid Freeform Fabrication Symposium

Open

Computer Aided Design

Numerical Simulation and Prediction of Dilution During Laser Deposition

Conference paper

https://repositories.lib.utexas.edu//bitstreams/fc2073a0-9057-4a1e-9f88-3c8eb4682d29/download

null

The laser additive manufacturing technique of laser deposition allows quick fabrication of fully-dense metallic components directly from Computer Aided Design (CAD) solid models. The applications of laser deposition include rapid prototyping, rapid tooling and part refurbishment. The development of an accurate predictive model for laser deposition is extremely complicated due to the multitude of process parameters and materials properties involved. In this work, a heat transfer and fluid flow model is developed. The model is used to predict dilution under varying process parameters for deposits of Ti-6Al-4V. Experimental validation of the predicted dilution is presented. The laser used is a direct diode laser.

null

['Dai, K.', 'Klemens, P.', 'Shaw, L.']

2019-09-23T16:43:06Z

2000

Mechanical Engineering

null

['https://hdl.handle.net/2152/75964', 'http://dx.doi.org/10.26153/tsw/3063']

eng

2000 International Solid Freeform Fabrication Symposium

Open

Densification

Numerical Simulation of Bi-Materials Laser Densification 386

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1de69a30-8d1d-43e2-8116-85b47b636a3e/download

null

The dominant procedure currently used for permanent fixed prosthodontics is porcelainfused-to-metal (PFM) restoration that is a time consuming and labor intensive process. To address these shortcomings, this project will develop a solid freeform fabrication (SFF) technique for dental restoration. Thus, a dental restoration can be built from a computer model without part-specific tooling and human intervention. The SFF technique to be developed is called multi-materials laser densification (MMLD) and capable of dealing with multiple dental materials such as dental alloys and porcelains. In order to provide guidelines for laser densification of multiple materials, numerical simulation has been carried out using the ANSYS code with 3-dimensional elements to model the temperature and stress fields during the MMLD process. Effects of laser scanning patterns and scanning rates have been investigated. Implications of these results on laser densification of multiple materials are discussed.

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

null

['Li, Mingyang', 'Tang, Lie', 'Xue, Fei', 'Landers, Robert']

2021-10-04T21:41:24Z

8/17/11

Mechanical Engineering

null

['https://hdl.handle.net/2152/88357', 'http://dx.doi.org/10.26153/tsw/15296']

eng

2011 International Solid Freeform Fabrication Symposium

Open

['ceramic paste extrusion', 'numerical simulation', 'non-Newtonian flow']

Numerical Simulation of Ram Extrusion Process for Ceramic Materials

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6277c698-8e09-4e81-9672-c06a40c3c94b/download

University of Texas at Austin

The freeze–form extrusion process for aqueous–based ceramic paste is complex due to the non– Newtonian behavior of the paste. In this paper the process is studied numerically using a developed mathematical model. The ceramic paste viscosity is characterized by the Herschel–Bulkley model. The relationship between plunger velocity and extrusion force is computed numerically. The influence of air, which is mixed with the paste during the loading process, is also examined. Due to the compressibility introduced by the trapped air, the plunger force dynamic response is typically dominated by a first order response. It is also shown that the extrusion plunger force depends on the volume of air in the extruder. Good agreement is obtained between the simulation results and experimental data.

null

['Shimono, Yusuke', 'Oba, Mototeru', 'Nomoto, Sukeharu', 'Koizumi, Yuichiro', 'Chiba, Akihiko']

2021-11-03T20:39:29Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89927

eng

2017 International Solid Freeform Fabrication Symposium

Open

['multi-phase field method', 'soldification', 'simulation', 'titanium alloy', 'additive manufacturing', 'MPFM']

Numerical Simulation of Solidification in Additive Manufacturing of Ti Alloy by Multi-Phase Field Method

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2ab6ba81-888f-4a86-980c-a6c4b41ad20a/download

University of Texas at Austin

The multi-phase field method (MPFM) coupled with the database of calculation of phase diagrams (CALPHAD) is a powerful tool for simulation of solidification microstructure evolution in engineering casting conditions. MPFM equations have been introduced assuming quasi-equilibrium at the interface. However, few attempts have been made adopting MPFM for solidification in additive manufacturing (AM) conditions because the process is considered to be in a strongly non-equilibrium condition. In other words, the classical solidification theory based on the local equilibrium assumption was not considered to be applicable to this process. However, some researchers have reported experimental observations of the columnar-to-equiaxed transition in the solidification of AM. These suggest MPFM can be adopted for solidification simulation of the AM process. We tackled the issue of applicability of MPFM for solidification simulation in AM of Ti alloys. It was confirmed that solidification simulation using MPFM can provide observation of the columnar-to-equiaxed transition and establish a solidification map for the AM process conditions.

null

['Luo, Zhibo', 'Zhao, Yaoyao Fiona']

2021-11-03T21:16:15Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89934

eng

2017 International Solid Freeform Fabrication Symposium

Open

['hybrid heat source', 'Gaussian point', 'line heat source', 'temperature field', 'powder bed fusion']

Numerical Simulation of Temperature Fields in Powder Bed Fusion Process by Using Hybrid Heat Source Model

Conference paper

https://repositories.lib.utexas.edu//bitstreams/11ac5719-065d-4719-9042-24cb348af682/download

University of Texas at Austin

Powder bed fusion (PBF) process is capable of producing a complex geometrical part with less material and energy consumption compared with conventional manufacturing methods. The performance of PBF processed part is mainly controlled by many process parameters such as scanning speed, scanning pattern, scanning strategy, and layer thickness. Usually, these parameters are optimized through detailed experiments which are time-consuming and costly. Therefore, numerical methods have been widely adopted to investigate the effects of these process parameters on temperature fields and thermal stress fields. As the laser/electron beam introduces huge temperature gradients within the irradiated region, which will result in the distortion even delamination of solidified layers, the study of the history of temperature distribution is the basic and crucial step in the modeling of PBF process. Most of the current research utilizes moving Gaussian point heat source as heat input to model the temperature distribution of a part. However, due to the small diameter of laser/electron beam, a small enough time step size is required to accurately model the real heat input, which will lead to significant computational burden. In this research, a hybrid of moving Gaussian point and line heat source model is developed, which makes the modeling of PBF process efficient without losing too much accuracy. In addition, an adaptive mesh scheme, which is capable of dynamically refining the mesh near the beam spot and coarsening the mesh far away from the beam spot, is adopted to accelerate the simulation process. Specifically, moving Gaussian point heat source is applied to the region of interest where accuracy is more concerned such as the temperature field within overhang feature. While the line heat source is applied to the region of interest where efficiency is more concerned such as temperature field within the inner region of a square. The simulation result shows that the temperature fields by using hybrid source model are comparable to the temperature fields by using the moving Gaussian point heat source model, and much less central processing unit time is required when the hybrid heat source is applied.

null

['Fan, Zhiqiang', 'Sparks, Todd E.', 'Liou, Frank', 'Jambunathan, Anand', 'Bao, Yaxin', 'Ruan, Jianzhong', 'Newkirk, Joseph W.']

2020-03-09T15:09:00Z

8/21/07

Mechanical Engineering

null

['https://hdl.handle.net/2152/80192', 'http://dx.doi.org/10.26153/tsw/7211']

eng

2007 International Solid Freeform Fabrication Symposium

Open

Computer Aided Design

Numerical Simulation of the Evolution of Solidification Microstructure in Laser Deposition

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0141a173-6643-497d-b4bd-c10a8847b02e/download

null

A predictive model is developed to simulate the evolution of the solidification microstructure during the laser deposition process. The microstructure model is coupled with a comprehensive macroscopic thermodynamic model. This model simulates dendritic grain structures and morphological evolution in solidification. Based on the cellular automata approach, this microstructure model takes into account the heterogeneous nucleation both within the melt pool and at the substrate/melt interface, the growth kinetics, and preferential growth directions of dendrites. Both diffusion and convection effects are included. This model enables prediction and visualization of grain structures during and after the deposition process. This model is applied to Ti-6Al-4V.

null

['Wang, L.', 'Felicelli, S.', 'Gooroochurn, Y.', 'Wang, P. T.', 'Horstemeyer, M. F.']

2020-03-02T15:26:13Z

9/14/06

Mechanical Engineering

null

['https://hdl.handle.net/2152/80132', 'http://dx.doi.org/10.26153/tsw/7153']

eng

2006 International Solid Freeform Fabrication Symposium

Open

Laser Engineered Net Shaping

Numerical Simulation of the Temperature Distribution and Solid-Phase Evolution in the LENS™ Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/bd67216f-b9cf-4335-9c46-7c202f0f9049/download

null

A three-dimensional finite element model was developed and applied to analyze the temperature and phase evolution in deposited stainless steel 410 (SS410) during the Laser Engineered Net Shaping (LENSTM) rapid fabrication process. The effect of solid phase transformations is taken into account by using temperature and phase dependent material properties and the continuous cooling transformation (CCT) diagram. The laser beam is modeled as a Gaussian distribution of heat flux from a moving heat source with conical shape. The laser power is optimized in order to achieve a pre-defined molten pool size for each layer. It is found that approximately 5% decrease of the laser power for each pass is required to obtain a steady molten pool size. The temperature distribution and cooling rate surrounding the molten pool are predicted and compared with experiments. Based upon the predicted thermal cycles and cooling rate, the phase transformations and their effects on the hardness are discussed.

null

['Zeng, D.', 'Rebandt, Matthew', 'Lacaria, Giuseppe', 'Lee, Ellen', 'Su, Xuming']

2021-11-18T17:19:33Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90434', 'http://dx.doi.org/10.26153/tsw/17355']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['numerical simulation', 'temperature history', 'plastic parts', 'fused filament fabrication', 'FFF']

Numerical Simulation of the Temperature History for Plastic Parts in Fused Filament Fabrication (FFF) Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b9d3d369-c22e-4c35-bd13-1e4064459495/download

University of Texas at Austin

Fused Filament Fabrication (FFF) is one of the major Additive Manufacturing (AM) processes for polymer materials. In FFF process, repetitive heating and cooling cycles occur when the filament is dispositioned onto a build platform to fabricate a three-dimensional part. The uneven temperature gradients and non-uniform cooling in the part may cause significant amount of warpage. The current practice of making an AM part to match the design intent is largely relied on time consuming trial-and-errors. Numerical simulation is an effective way to predict warpage. Accurate prediction of the thermal history during the FFF process is key for the success of warpage simulation. In this paper, an integrated approach is developed in LS-DYNA to model the FFF process and predict the temperature profile. Different from the traditional approaches, the tool path and FEM mesh are decoupled in this study to enable the flexibility of FEA mesh generation and improve computational efficiency. An innovated micro thermocouple is used to measure the temperature history inside the parts. The evolution of the thermal history is predicted and compared to the measurement data to demonstrate the accuracy and efficiency of the developed simulation model.

null

Hsu, Michael B.

2018-04-19T18:12:28Z

1992

Mechanical Engineering

doi:10.15781/T28C9RM8S

http://hdl.handle.net/2152/64399

eng

1992 International Solid Freeform Fabrication Symposium

Open

['creep models', "Poisson's ratio", 'apparent modulus']

Numerical Simulation of Viscous Sintering under Mechanical Loads

Conference paper

https://repositories.lib.utexas.edu//bitstreams/075814fc-7a8d-4e92-a6e2-61d088a96fd4/download

null

['Tan, W.', 'Gibson, I.']

2020-02-20T19:45:29Z

8/3/05

Mechanical Engineering

null

https://hdl.handle.net/2152/80044

eng

2005 International Solid Freeform Fabrication Symposium

Open

['microstereolithography', 'recoating process', 'numerical simulation']

Numerical Study on the Recoating Process in Microstereolithography

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0f27c30a-38e1-4d75-b0e3-5abc51ce16cd/download

null

Microstereolithography is a promising RP-based micro-fabrication technique that aims to meet the demands for complex geometry micro-scale parts. Projection microstereolithography incorporates a Dynamic Pattern Generator to obtain high resolution in the parallel plane. However, its lateral resolution has been always limited by the final layer thickness and the long resin settling time, both of which rely on the recoating process. In order to find the critical factors behind the recoating process, a numerical simulation method (Computational Fluid Dynamics, CFD) has been used to investigate the relationships among final layer thickness, settling time, resin viscosity and ratio of object/container size. These results are helpful for the selection of resin characteristics and the design of the microstereolithography machine.

null

['Shen, Ninggang', 'Chou, Kevin']

2021-10-06T21:33:55Z

8/16/12

Mechanical Engineering

null

['https://hdl.handle.net/2152/88451', 'http://dx.doi.org/10.26153/tsw/15388']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['electron beam additive manufacturing', 'thermal models', 'preheating temperatures', 'complex process configurations', 'temperature field']

Numerical Thermal Analysis in Electron Beam Additive Manufacturing with Preheating Effects

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8bc4626f-e4aa-4290-98d3-f03a61b463df/download

University of Texas at Austin

In an early study, a thermal model has been developed, using finite element simulations, to study the temperature field and response in the electron beam additive manufacturing (EBAM) process, with an ability to simulate single pass scanning only. In this study, an investigation was focused on the initial thermal conditions, redesigned to analyze a critical substrate thickness, above which the preheating temperature penetration will not be affected. Extended studies are also conducted on more complex process configurations, such as multi-layer raster scanning, which are close to actual operations, for more accurate representations of the transient thermal phenomenon.

null

['Ikeshoji, T.-T.', 'Kyogoku, H.', 'Yonehara, M.', 'Araki, M.', 'Nakamura, K.']

2021-10-26T19:18:47Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89562

eng

2016 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', 'nickel alloy', 'numerical transient analysis', 'heat transfer', 'powder bed', 'multilayer track']

Numerical Transient Heat Transfer Analysis of Multi Laser Track on Powder Bed of Ni-Based Alloy

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8ffdbd6e-8cbc-45aa-aa9a-62ed86848834/download

University of Texas at Austin

The numerical transient heat transfer analysis is conducted for SLM process of Ni-based alloy. For the initial situation, the powder layer covers all the top surface of bulk substrate. Then it is simulated a laser spot scans one and half times of round trips. To simulate the melting of powder layer and its solidification, the powder elements are changed to the bulk when the powder element’s temperature reaches to liquidus. The results show the change in melt pool shape. It is symmetry about scanning direction axis for the first path, but the second and third paths’ melt pool is wider on the solidified side. The melt pool dimensions are compared with the experimentally obtained thermography images. The estimated melt pool depth is also compared with the metallographic microstructure image of cross section. The results might suggest the one-path simulation is not enough for the prediction of solidified track of SLM process.

null

['Nzebuka, Gaius Chukwuka', 'Ufodike, Chukwuzubelu Okenwa']

2023-02-17T14:46:13Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117486', 'http://dx.doi.org/10.26153/tsw/44367']

eng

2022 International Solid Freeform Fabrication Symposium

Open

filament

Numerical Transient Thermal Development of Melting a Solid Filament in a Hot-end of a Material Extrusion System

Conference paper

https://repositories.lib.utexas.edu//bitstreams/22c1cef6-8927-425e-a8f7-ed554a46d058/download

null

Additive manufacturing of polymer feedstock in the form of solid filament is challenging due to heat transfer limitations. The ease of melting the filament in the liquefier influences the production rate and life cycle of the hot-end components. This study presents numerical transient thermal development during the melting of the solid filament in the liquefier. The sample filament material selected for the study is a tough polylactic acid (TPLA). The transient computation of thermal distribution and liquid fraction evolution was performed using computational fluid dynamics (CFD) commercial software. However, the numerical model formulations cannot be directly applied to the available CFD software. Therefore, a user-defined function (UDF) was written and interfaced with the CFD software for the properties field-dependent functions. Special care was taken to capture the motion of the solid filament by patching the velocity explicitly in the flow domain. One simulation was performed without accounting for the velocity of the translating solid filament and the result obtained revealed that the case that accounts for the velocity of the solid filament predicts the infrared thermographic measured nozzle exit temperature of the extrudate more accurately. Also, a steady thermal development was achieved in the hot end after 25 seconds. The transient thermal analysis can be useful for a better understanding of melting dynamics in the liquefier and assist in process control planning.

null

['Chung, Marilyn', 'Malone, Evan', 'Tolley, Michael T.', 'Chepaitis, Andrew J.', 'Lipson, Hod']

2021-09-23T22:47:43Z

9/10/08

Mechanical Engineering

null

['https://hdl.handle.net/2152/88046', 'http://dx.doi.org/10.26153/tsw/14987']

eng

2008 International Solid Freeform Fabrication Symposium

Open

['rapid prototyping technology', 'object augmentation', 'visually impaired']

Object Augmentation for the Visually Impaired Using RP

Conference paper

https://repositories.lib.utexas.edu//bitstreams/083eda81-318e-40a7-b478-d9c3af49f6b5/download

null

We demonstrate the application of rapid prototyping technology to augment every-day objects for the visually impaired. A freeform fabricator was used to print a tactile alphabet on multiple surfaces including paper, plastic, and metal. We have identified and experimented with multiple non-toxic materials and analyzed the dimensional tolerance, repeatability, and adhesion characteristics on multiple surfaces. Printing time for 1x1cm embossed letters varied from 14 to 52 seconds. More broadly, these experiments open the door to RP applications that involve custom product adaptation to address disabilities.

null

['Tilli, J.', 'Fantoni, G.', 'Currenti, S.', 'Razionale, A.V.']

2021-10-12T20:26:52Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88733', 'http://dx.doi.org/10.26153/tsw/15667']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['Rapid Prototyping', 'removal manufacturing', 'object shaping', 'polystyrene', 'sonotrode']

Object Shaping of Polystyrene with a Sonotrode

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ee8e8702-bb59-4181-badd-d6a0c67dafab/download

University of Texas at Austin

Rapid Prototyping methods are often based on additive manufacturing strategies. Depending on the application, it can also be considered the use of a removal manufacturing rapid prototyping methodology. In this paper the authors investigate the possibility of using the ultrasound technology for the shaping of materials that can be considered as a final object, or as a rapid manufactured mold for the creation of prototypes. In this case, free-form objects can be manufactured starting from foam like materials, and model the foam through the use of a ultrasonic horn thus shaping the desired features. The authors tested the possibility of implementing the technology onto automated systems, allowing considering the use of this system on automated manufacturing lines. Geometrical deviations from the 3D model are measured and material morphology before and after machining is analyzed.

null

['Landers, Robert G.', 'Hilgers, Michael', 'Liou, Frank W.', 'McMillin, Bruce M.']

2019-10-23T15:10:45Z

2002

Mechanical Engineering

null

['https://hdl.handle.net/2152/76756', 'http://dx.doi.org/10.26153/tsw/3845']

eng

2002 International Solid Freeform Fabrication Symposium

Open

Object-Oriented

Object-Oriented Modeling and Fault Detection of a Powder Feeder for a Laser Metal Deposition System

Conference paper

https://repositories.lib.utexas.edu//bitstreams/528375a8-6a3d-4be2-a4ca-07a9eb7375e9/download

null

One of the most critical components of a laser metal deposition system is the powder feeder unit. Techniques are required to efficiently design and analyze these systems and to ensure fault tolerance during the operation. In this paper, a model of the powder feeder unit, based on object– oriented abstractions of it components, is developed. This model is modular in that specific components can be efficiently updated or replaced with components that perform a similar function. In addition, the model can be used for simulation allowing for efficient design and analysis. Assurance of the correctness of the powder feeder system is obtained from concurrent run–time evaluation of temporal logic expressions. A simulation example is provided.

The authors gratefully acknowledge their students’ contributions to this paper and the financial support of the National Science Foundation (DMI–9871185), Missouri Research Board, Society of Manufacturing Engineers, and Missouri Department of Economic Development.

null

['Scharowsky, T.', 'Baureiβ, A.', 'Singer, R.F.', 'Körner, C.']

2021-10-06T21:48:08Z

2012

Mechanical Engineering

null

['https://hdl.handle.net/2152/88454', 'http://dx.doi.org/10.26153/tsw/15391']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['selective electron beam melting', 'beam powder interaction', 'melt pool dynamic', 'Ti6Al4V']

Observation and Numerical Simulation of Melt Pool Dynamic and Beam Powder Interaction During Selective Electron Beam Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6b98b93a-ca59-41b8-ba91-d29b80119e56/download

University of Texas at Austin

Selective electron beam melting (SEBM) is an additive manufacturing method used to produce complex parts in a layer-by-layer process utilizing Ti6Al4V powder. To improve the very good properties of built parts even more and to use the full capacity of the process, the fundamental understanding of the beam powder interaction is of essential relevance. Numerical simulations and observation with a high speed camera of powder melting show the strong melt pool dynamic and its lateral extent clearly. Furthermore, the immediate effect of beam parameters, e.g. beam current and velocity, on the melting behavior of the powder can be resolved in time steps of a few milliseconds.

null

['Lawrence, Jacob', 'Inkley, Colton', 'Fezzaa, Kamel', 'Clark, Samuel J.', 'Crane, Nathan B.']

2023-01-27T17:58:23Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117350', 'http://dx.doi.org/10.26153/tsw/44231']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Binder Jetting', 'Synchrotron X-ray Imaging', 'Binder-Powder Interaction', 'Print Processing Parameters', 'Metal']

Observations of Binder Jetting Defect Formation Using High-Speed Synchrotron X-Ray Imaging

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a47cb13e-f9a9-4246-ac5d-49bb7349ca93/download

null

The Binder Jetting (BJ) process is capable of producing parts at high speeds from a variety of materials, but performance is limited by defects in the final parts. An improved understanding of fundamental phenomena in the printing process is needed to understand the source of these defects. This work presents initial findings from high-speed imaging of the BJ process using synchrotron X-rays. High-speed X-ray imaging allows for direct observation of key physical mechanisms in the printing process that may introduce defects including binder droplet impact on the powder bed, powder rearrangement below and above the powder bed surface, and balling formation. Testing was performed with multiple materials and droplet spacings to compare the effect on observed phenomena. Multiple lines were printed on packed and loose powder beds to further explore factors that affect defect formation and to better simulate industrially relevant conditions.

null

['Dhaveji, Ch. Sweta', 'Sparks, Todd E.', 'Ruan, Jianzhong', 'Liou, Frank W.']

2021-10-04T21:49:40Z

2011

Mechanical Engineering

null

['https://hdl.handle.net/2152/88360', 'http://dx.doi.org/10.26153/tsw/15299']

eng

2011 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing toolpath', 'machine simulation', 'multi axis AM']

Octree Approach for Simulation of Additive Manufacturing Toolpath

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e1bb96a2-6fb4-4f05-9357-267ed0773327/download

University of Texas at Austin

Machine simulation is an effective way of checking additive manufacturing tool paths for both interferences and errors in part produced. This paper presents an algorithm to visually simulate a multi axis additive manufacturing system as it executes a process plan. Simulation results are intended to be used as a verification step before physically producing the part. Verification is particularly important for large builds of expensive materials. The algorithm uses an octree approach to efficiently model the deposition of part geometry and its changes. This paper discusses development of the simulation algorithm, including both the representation of the additive manufacturing machine and the octree data model of the part being produced.

null

['Tang, Hwa-Hsing', 'Yen, H.C.', 'Len, Wen-Hsiang']

2019-11-21T18:04:29Z

2003

Mechanical Engineering

null

['https://hdl.handle.net/2152/78550', 'http://dx.doi.org/10.26153/tsw/5606']

eng

2003 International Solid Freeform Fabrication Symposium

Open

Rapid Prototyping

On Ceramic Parts Fabricated Rapid Prototyping Machine Based on Ceramic Laser Fusion

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9659a125-28ca-4e36-adff-7f2b7a927cb3/download

null

Conventional ceramic manufacture processes are not feasible to make ceramic parts with complex shape because of restrictions such as high tooling cost, time consuming and skillful workmanship. A new facility taking advantage of patented Ceramic Laser Fusion (CLF) technology to fabricate complex ceramic parts automatically is developed. According to the samples made by CLF machine, they are verified that hollow and over hung structures can be supported by solid green portion and complex ceramic parts can be fabricated. Apparently, this facility could promote the applications of ceramic materials, such as direct fabrication of ceramic shell mold.

null

['Papadatos, Alexandre L.', 'Ahzi, Said', 'Deckard, Carl R.', 'Paul, Frank W.']

2018-12-07T17:10:44Z

1997

Mechanical Engineering

doi:10.15781/T2BR8N26F

http://hdl.handle.net/2152/71451

eng

1997 International Solid Freeform Fabrication Symposium

Open

['dimensional stabilities', 'Rapid prototyping']

On dimensional stabilities: Modeling of the Bonus-Z during the SLS Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c51c4197-a193-40cb-8baa-b498711705e5/download

null

This work is a first step towards the prediction of the dimensions and thermomechanical properties ofparts made with the Selective Laser Sintering (SLS) technology. An important variation of the dimensions is found in the Z-direction of the build. This phenomenon is known as the "Bonus-Z" where material properties differ from those in the rest of the part due to a non-homogeneous sintering. The focus of this work is the characterization and the modeling of the bonus-Z phenomenon, by relating it to the energy input. The polymer powder used in this study is polycarbonate.

null

['Thien, Austen', 'Kelly, Kathryn M.', 'Massey, Caroline E.', 'Saldana, Christopher J.']

2024-03-26T23:17:04Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124446', 'https://doi.org/10.26153/tsw/51054']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['wire-arc additive manufacturing', 'stability', 'aluminum alloy']

ON PROCESS STABILITY IN WAAM-CMT OF ALUMINUM ALLOYS

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e4624232-4d1a-4b35-8bcf-ba16bcd8a916/download

University of Texas at Austin

Wire-arc additive manufacturing (WAAM) has become a cost-efficient metal additive manufacturing process. However, depositing aluminum with WAAM is challenging due to its sensitivity to heat input (linear energy density), which can cause undesirable surface topology waviness if not controlled. Thus, a process window is needed that can produce stable geometry and deposition conditions while minimizing production times. In this study, 5183 aluminum alloy wire is used to deposit 10-layer walls with varying wire feed speeds (WFS) and traverse speeds (TS) (at a constant WFS/TS ratio) and varying interpass temperature (IPT). In-situ process data consisting of optical contact-tip-workpiece-distance (CTWD) and current/voltage measurements are collected to determine process condition stability throughout the build. Part geometry is measured using a 3D scanner and build porosity is characterized via digital X-ray. A process window is identified that produces stable surface topology and process conditions at a minimal production time.

null

Das, Suman

2019-10-09T16:15:31Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76151', 'http://dx.doi.org/10.26153/tsw/3240']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Sintering

On Some Physical Aspects of Process Control in Direct Selective Laser Sintering of Metals Part I

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f629627a-7dba-411a-8ae1-57b45757085b/download

null

Das, Suman

2019-10-09T16:17:13Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76152', 'http://dx.doi.org/10.26153/tsw/3241']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Sintering

On Some Physical Aspects of Process Control in Direct Selective Laser Sintering of Metals Part II

Conference paper

https://repositories.lib.utexas.edu//bitstreams/44409a12-9f12-49a6-86e6-ee89e7eff871/download

null

Das, Suman

2019-10-09T16:18:26Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76153', 'http://dx.doi.org/10.26153/tsw/3242']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Sintering

On Some Physical Aspects of Process Control in Direct Selective Laser Sintering of Metals Part III

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1b5b84ff-de0e-40cc-bfce-bbaa56b570ef/download

null

['Allen, Seth', 'Dutta, Deba']

2018-10-03T15:51:40Z

1994

Mechanical Engineering

doi:10.15781/T24F1N368

http://hdl.handle.net/2152/68653

eng

1994 International Solid Freeform Fabrication Symposium

Open

['Layered manufacturing', '3D System machines', 'photocurable liquid']

On the Computation Of Part Orientation Using Support Structures in Layered Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/92effa27-1c59-4792-822e-50a4e5e951a0/download

null

During the construction of an object by layered manufacturing, it might be necessary to build external supports either to prevent the object from toppling, or to support floating components and overhanging material. The support structures, if necessary, must be built simultaneously with the object, and hence must be accounted for in the path planning of the laser beam or the deposition nozzle. In this paper, we find the best direction offormation of an object by layered manufacturing process that allows the use of support structures. In the orientation determined by the best direction offormation, the object is constructible with a minimal support structure, is stable, and rests on a planar base. Implementation results are also included.

null

['Wood, Nathaniel', 'Schwalbach, Edwin', 'Gillman, Andrew', 'Hoelzle, David J.']

2021-12-01T22:28:47Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90639', 'http://dx.doi.org/10.26153/tsw/17558']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['powder bed fusion', 'ensemble kalman filter', 'thermal camera', 'camera resolution']

On the Diminishing Returns of Thermal Camera Resolution for PBF Temperature Estimation

Conference paper

https://repositories.lib.utexas.edu//bitstreams/68cc0198-20ba-4bbb-bec0-8c6054d1afca/download

University of Texas at Austin

Powder Bed Fusion (PBF) faces ongoing challenges in the areas of process monitoring and control. Standard methods for alleviating these issues rely on machine learning, which requires costly and time-consuming training data. Expense is compounded by the perceived necessity of using sensors with extremely high resolutions. This research avoids this cost by employing an Ensemble Kalman Filter (EnKF), which uses measured data to correct physics-based model predictions of the process, to monitor part internal temperature fields during building. This work tests EnKF performance, in simulation, for two model architectures, using simulated cameras of varying resolution as our measuring instruments. Crucially, we show that increasing camera resolution produces diminishing returns in EnKF accuracy, relative to the model predictions, with up to 81% error reduction. This result shows that current AM quality control practices with expensive sensors may be inefficient; with appropriate algorithms, cheaper setups may be used with little additional error.

null

['Goossens, Louca R.', 'Kinds, Yannis', 'Kruth, Jean-Pierre', 'Van Hooreweder, Brecht']

2021-11-15T22:39:02Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90299', 'http://dx.doi.org/10.26153/tsw/17220']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['thermal lensing', 'focal shift', 'high power laser', 'control', 'SLM']

On the Influence of Thermal Lensing During Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/14391a10-9f34-4b6c-a43e-6fc5bdd840a0/download

University of Texas at Austin

Multi kilowatt single mode lasers are increasingly being used in Selective Laser Melting (SLM), typically with the aim of improving productivity. However, the high power densities present in the optical path lead to a thermally induced focal shift i.e. thermal lensing. Whilst thermal lensing has been studied for many processes, its impact on parts produced by SLM is currently unknown. Therefore this work discusses the characteristics of a thermally induced focal shift supplemented by a method for the compensation of this effect. In addition, SLM parts with and without thermal lensing compensation are compared in order to show the effect on final part quality.

null

['Gill, D.D.', 'Smugeresky, J. E.', 'Harris, M. F.', 'Robino, C. V.', 'Griffith, M. L.']

2020-02-14T15:22:44Z

2004

Mechanical Engineering

null

['https://hdl.handle.net/2152/79984', 'http://dx.doi.org/10.26153/tsw/7009']

eng

2004 International Solid Freeform Fabrication Symposium

Open

Laser Engineered Net Shaping

On the Interface Between LENS® Deposited Stainless Steel 304L Repair Geometry and Cast or Machined Components

Conference paper

https://repositories.lib.utexas.edu//bitstreams/bc812b8a-9bf7-46fe-b267-c2ca3995ff9c/download

null

Laser Engineered Net Shaping™ (LENS®) is being evaluated for use as a metal component repair/modification process. A component of the evaluation is to better understand the characteristics of the interface between LENS deposited material and the substrate on which it is deposited. A processing and metallurgical evaluation was made on LENS processed material fabricated for component qualification tests. A process parameter evaluation was used to determine optimum build parameters and these parameters were used in the fabrication of tensile test specimens to study the characteristics of the interface between LENS deposited material and several types of substrates. Analyses of the interface included mechanical properties, microstructure, and metallurgical integrity. Test samples were determined for a variety of geometric configurations associated with interfaces between LENS deposited material and both wrought base material or previously deposited LENS material. Thirteen different interface configurations were fabricated for evaluation representing a spectrum of deposition conditions from complete part build, to hybrid substrate-LENS builds, to repair builds for damaged or re-designed housings. Good mechanical properties and full density were observed for all configurations. When tested to failure, fracture occurred by ductile microvoid coalescence. The repair and hybrid interfaces showed the same metallurgical integrity as, and had properties similar to, monolithic LENS deposits.

null

['Casanova, Lucas', 'Anitha, Vineeth Vijayan', 'Kadway, Nikhil', 'Gandhi, Arpit', 'Le, Thao', 'Lee, Christine', 'Bhate, Dhruv']

2021-11-09T20:13:17Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90153', 'http://dx.doi.org/10.26153/tsw/17074']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['asymmetric honeycombs', 'mechanical behavior', 'material design', 'additive manufacturing']

On the Mechanical Behavior of Additively Manufactured Asymmetric Honeycombs

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4e3fec48-189c-4190-9bb5-c2d0981911df/download

University of Texas at Austin

From a design perspective, there are four decisions that need to be made when integrating cellular materials such as lattices and honeycombs into a structure: selection of the unit cell type, distribution of the size of the cells across the structure, optimization of individual cell walls/struts and junction thicknesses, and finally, integration of the cellular material with the outer form of the larger structure it is a part of. In this paper, we explore an alternative approach to designing cellular materials, borrowing concepts of symmetry from mathematics and the arts to manipulate 2- dimensional square honeycombs of uniform thickness, starting from a regular, periodic square, gradually varying symmetry and the number of shapes to create a range of forms. We report results of compression testing of specimens made with the Fused Deposition Modeling process, and study the effective specific properties of the honeycombs with regard to their peak stress at failure, densification strain and energy absorption. We report weak to no correlation to the first two of these, but demonstrate how asymmetry and negative space may be leveraged to formulate design principles for energy absorption.

null

['Sager, Benay', 'Rosen, David W.']

2020-02-14T16:18:56Z

8/31/04

Mechanical Engineering

null

['https://hdl.handle.net/2152/79991', 'http://dx.doi.org/10.26153/tsw/7016']

eng

2004 International Solid Freeform Fabrication Symposium

Open

Stereolithography

On the Use of Angled, Dynamic Laser Beams to Improve Stereolithography Surface Finish

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ed15bf7b-4ffc-48a7-93b4-57eb806e11a2/download

null

Improved surface finish of Stereolithography (SLA) parts is an important goal for furthering the resolution of the technology. In order to improve the surface finish, a dynamic laser beam with changing angle, beam size, beam shape, and irradiance distribution is proposed. In this paper, an analytical irradiance model of an angled, dynamic laser beam in the SLA process is presented. This model is used to simulate cured shapes of SLA builds. Simulated build shapes are compared to established SLA analytical models and conclusions are drawn on the accuracy of the developed model.

null

['Hyde, C.J.', 'Xu, Z.', 'Thompson, A.', 'Leach, R.K.', 'Maskery, I.', 'Tuck, C.J.', 'Clare, A.T.']

2021-11-02T14:41:03Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89813

eng

2017 International Solid Freeform Fabrication Symposium

Open

['creep', 'two-bar specimen', 'x-ray computed tomography', 'laser powder bed fusion', 'inconel 718']

On the Use of X-Ray Computed Tomography for Monitoring the Failure of An Inconel 718 Two-Bar Specimen Manufactured by Laser Powder Bed Fusion

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7de5b0b8-7ffa-4c59-b9e2-89844c3ff60f/download

University of Texas at Austin

Additive manufacturing technologies are highly versatile, capable of producing components with previously impossible complex geometries. However, when additive manufacturing is used to produce parts for critical applications, such as in the aerospace sector, the parts are sometimes limited by poor mechanical properties; largely as a result of porosity and lower material homogeneity than found in, for example, a wrought equivalent. Presented here is a method for identifying material defects, such as porosity, and for monitoring the progress of these defects towards failure during a mechanical test. An Inconel 718 two-bar specimen, produced by laser powder bed fusion, has been applied to a “staged” mechanical test, and X-ray computed tomography used to measure the sample at the end of each “stage”. The X-ray computed tomography data has then been used to provide a history of failure sites prior to failure.

null

['Beascoechea, Alejandro', 'Wozny, Michael J.']

2018-11-02T17:05:34Z

1995

Mechanical Engineering

doi:10.15781/T24J0BH0P

http://hdl.handle.net/2152/69341

eng

1995 International Solid Freeform Fabrication Symposium

Open

['SFF technology', 'optimization', 'fabrication']

On Three Dimensional Heuristic Packing For Solid Freeform Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ce55811f-464c-439f-b5f6-322673facc4d/download

null

Optimal packing, any dimension, is computationally intractable. Here we address the particular problem of automatically generating good layouts of arbitrary solid three-dimensional shape models into a container region that represents a given freeform fabrication manufacturing chamber. We put forth a multistage approach that combines modem heuristic optimization methods with computational geometry techniques. Our aim is to secure satisfactory and practical results for a problem for which reaching optimal packing configurations is computationally unattainable.

null

['Fouchal, F.', 'Knight, J.A.G.', 'Dickens, P.', 'Garrington, N.']

2019-10-18T16:11:32Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76249', 'http://dx.doi.org/10.26153/tsw/3338']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Epoxy Resin

On-line Monitoring of Epoxy Resin Cure using Infrared Spectroscopy

Conference paper

https://repositories.lib.utexas.edu//bitstreams/fa8356f9-11ce-4e5f-bd44-a134899eaa90/download

null

The method described can be used to observe the cure in epoxy resins, it is a sensor to serve as an on line monitoring system of physical change of the resins during the curing time and the future behaviour of the part built. It is also proposed that the method can be applied in Stereolithography (SL). In this paper the method permits a rapid determination of the state of chemical reaction happening in an epoxy resin diglycidyl ether of bisphenol A (DGEBA) with a curing agent triethylenetetramine stoichiometric mixture. It uses a mid infrared Fourier transform (FT-IR) technique to analyse the mixture via an embedded fibre optic and an FT-IR spectrometer operating in the region of 4000-700 cm-1. An accurate concentration versus time of epoxy amine and the hydroxyl groups gave a good estimate of the extent of reaction. The chemical group peaks at 1132cm-1 and 3300-3400cm-1 where used to follow the disappearance of the epoxy, and the amine respectively, while the peak at 2970cm-1 was used as reference peak. A review of a number of techniques used in the study of the curing process of epoxy resins and a number of methods used in an on-line monitoring of thermoset resin cure process is referred to Keywords: Streolithography, epoxy/amine cure, FT-IR spectroscopy, extent of reaction, fiber optic sensor.

null

['Yang, Liu', 'Binega, Eden', 'Cheng, Jack C.P.', 'Jeon, Ikgeun', 'Sohn, Hoon']

2021-12-01T23:08:11Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90649', 'http://dx.doi.org/10.26153/tsw/17568']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['directed energy deposition', 'laser line scanner', 'geometry quality', 'quality management', 'online management']

Online Geometry Quality Management during Directed Energy Deposition using Laser Line Scaner

Conference paper

https://repositories.lib.utexas.edu//bitstreams/efcc630c-c6ee-4db3-ac53-c33b79e6515d/download

University of Texas at Austin

Additive manufacturing (AM) is a powerful and promising manufacturing technology due to its advantages of material saving, mass customization and small-quantity production of custom-designed products. However, current situation of lacking quality management in 3D printing process is the key barrier of adopting this advanced technology. Geometry inaccuracy of 3D printed components is one of the main quality problems for AM, especially when the final product requires high precision in its geometry. In this study, an online geometry quality management method for continuous monitoring during the direct energy deposition (DED) process was developed using a laser line scanner. Our proposed methodology comprises: (1) real-time track-by-track scanning of multi-layer single-track component, (2) online geometry extraction of multi-layer single-track component during printing process, and (3) online plotting and comparison of the as-designed and as-built models.

null

['Craeghs, Tom', 'Clijsters, Stijn', 'Yasa, Evren', 'Kruth, Jean-Pierre']

2021-10-04T21:21:50Z

8/17/11

Mechanical Engineering

null

['https://hdl.handle.net/2152/88350', 'http://dx.doi.org/10.26153/tsw/15289']

eng

2011 International Solid Freeform Fabrication Symposium

Open

['Selective Laser Melting', 'quality monitoring', 'quality control', 'online quality control']

Online Quality Control of Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ed92c4ed-fd04-4ba7-a4c4-d84b790dea2e/download

University of Texas at Austin

Selective Laser Melting (SLM) is an Additive Manufacturing technique which allows producing three-dimensional metallic parts from powder material, using a layer-by-layer fashion. Typical applications of this technology are parts with high geometrical complexity or internal features such as biomedical implants or casting molds with conformal cooling channels. In order to break through in industries with very high quality standards (such as aerospace industries), an important issue to be addressed is quality monitoring and control during the actual building process. Online quality control can significantly increase the robustness of the process by enabling to check the quality of the building process in the earliest possible stage, such that eventually corrective actions can be taken during the process. This is in contrast with on-line and a posteriori quality control which does not allow taking corrective measures if the quality of the part does not meet the desired quality standard. The development of a framework for online quality control of Selective Laser Melting is the subject of this paper. The framework consists of two complementary systems: a system for visual inspection of powder deposition and a system for online and real-time monitoring of the melt pool. A combination of these two systems enables to guarantee the quality of SLM parts with high confidence.

null

['Tang, Shangyong', 'Wang, Guilan', 'Zhang, Haiou', 'Wang, Rui']

2021-11-04T18:25:17Z

2017

Mechanical Engineering

null

['https://hdl.handle.net/2152/89998', 'http://dx.doi.org/10.26153/16919']

eng

2017 International Solid Freeform Fabrication Symposium

Open

['online surface defects detection system', 'surface defects', 'defect detection', 'deep learning', 'support vector', 'arc welding based additive manufacturing', 'AWAM']

An Online Surface Defects Detection System for AWAM Based on Deep Learning

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3a1a2938-334b-41e0-b163-e61cb6383e49/download

University of Texas at Austin

Defects detecting layer by layer in arc welding based additive manufacturing (AWAM) is a big challenge as it affects the successive layer quality of the products. Most of the work on layer quality defection were focused on 3D profile measurement and X-ray spectroscopy method but it is inefficient, expensive with poor adaptability. In this work, an online intelligent surface defects detection system for AWAM was developed through deep learning algorithm and support vector machine method. To achieve a reliable surface feature of the welding beads, a vision sensor was used to get the image of the shaped surface synchronously. The system was trained offline and online to acquire knowledge of the welding beads which were classified into five patterns as normal, pore, hump, depression and undercut. An defection test result showed 95.29% accuracy. The system was verified to be practical with high accuracy and efficiency for the surface defects.

null

['Hartman, Aja', 'Baker, Mary', 'Tastl, Ingeborg', 'Nauka, Krzysztof']

2023-01-20T13:53:28Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117253', 'http://dx.doi.org/10.26153/tsw/44134']

eng

2022 International Solid Freeform Fabrication Symposium

Open

MJF

Opacity Modulation in Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/24c1ba80-88c7-45af-ba3f-21ca98e02b35/download

null

HP’s powder-based technology, Multi Jet Fusion (MJF), uses a fusing agent to selectively melt polymer powder in a layer-by-layer fashion to create 3D parts. There are many applications that require variable opacity including signage, medical models, and backlit buttons and indicators on computers, vehicles, and instruments. The industry also needs to replicate different materials that have varying optical properties throughout their thickness, such as skin or tortoiseshell, and to enable techniques such as covert markings on parts. Although completely opaque parts are achievable by doping the base powder material with an opacifying material, this opacifying method makes the whole part opaque instead of allowing variability at a voxel level. By modulating both opacifying agent loading and the geometric design of the opaque part region in our MJF platform, we have achieved variable optical properties within parts, modulating optical transmission from 48 % to 1 %.

null

['Carter, William', 'Tucker, Michael', 'Mahony, Michael', 'Toledano, David', 'Butler, Robert', 'Roychowdhury, Subhrajit', 'Nassar, Abdalla R.', 'Corbin, David J.', 'Benedict, Mark D.', 'Hicks, Adam S.']

2021-11-16T15:37:04Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90316', 'http://dx.doi.org/10.26153/tsw/17237']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['open scan path', 'selective laser melting', 'acceleration of large-scale additive manufacturing', 'ALSAM', 'Air Force']

An Open-Architecture Multi-Laser Research Platform for Acceleration of Large-Scale Additive Manufacturing (ALSAM)

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2005da82-0de6-4f58-a656-a8e98dbdc621/download

University of Texas at Austin

As Selective Laser Melting (SLM) technology matures, researchers and engineers responsible for transitioning the technology from rapid prototyping into manufacturing are gaining a better understanding of the opportunities with this revolutionary technology. A step for accelerating solutions is to allow researchers complete access to all aspects of the process for experimentation. As part of an AFRL-sponsored program with America Makes, a production-grade SLM machine (a Concept Laser M2) will be enhanced to allow operation with either the original OEM controls and scan path generation or an open-source set of software developed under America Makes programs. This machine will be referred to as the ALSAM Platform and will be delivered to the Air Force along with the source code for the open scan path generation software (written in C++) and the open machine controller (written in LabVIEW™).

null

['Elliott, A.M.', 'Love, L.J.']

2021-10-28T22:44:51Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89722

eng

2016 International Solid Freeform Fabrication Symposium

Open

['metal additive manufacturing', 'operator burden', 'build cycle', 'part processing', 'reset']

Operator Burden in Metal Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/eb250543-2d70-4dfd-8ebb-0d8f2bf5458d/download

University of Texas at Austin

Additive manufacturing (AM) is an emerging manufacturing process that creates usable machine parts via layer-by-layer joining of a stock material. With this layer-wise approach, high-performance geometries can be created which are impossible with traditional manufacturing methods. Metal AM technology has the potential to significantly reduce the manufacturing burden of developing custom hardware; however, a major consideration in choosing a metal AM system is the required amount of operator involvement (i.e., operator burden) in the manufacturing process. The operator burden not only determines the amount of operator training and specialization required but also the usability of the system in a facility. As operators of several metal AM processes, the Manufacturing Demonstration Facility (MDF) at Oak Ridge National Labs is uniquely poised to provide insight into requirements for operator involvement in each of the three major metal AM processes. The paper covers an overview of each of the three metal AM technologies, focusing on the burden on the operator to complete the build cycle, process the part for final use, and reset the AM equipment for future builds.

null

['Foster, B.K.', 'Reutzel, E.W.', 'Nassar, A.R.', 'Hall, B.T.', 'Brown, S.W.', 'Dickman, C.J.']

2021-10-19T19:20:04Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89328

eng

2014 International Solid Freeform Fabrication Symposium

Open

['powder bed fusion', 'additive manufacturing', 'layer-wise imaging']

Optical, Layerwise Monitoring of Powder Bed Fusion

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f99366e0-828f-4a6c-b890-44313eecc83b/download

University of Texas at Austin

In powder bed fusion additive manufacturing, pre-placed layers of powder are successively fused to form three-dimensional components. During part build-up, flaws in the material or part geometry can occur and lead to an unacceptable part quality. Common flaws include porosity, poor surface finish, and thermal deformation. Here, a layer-wise imaging technique is presented for process monitoring. The technique relies on collection and analyses of images taken under oblique illuminations of fused and pre-placed powder layers. Results of three-dimensional reconstruction of image data and identification of potential flaws are presented.

null

['Ray, Phillip', 'Chahine, Gilbert', 'Smith, Pauline', 'Kovacevic, R.']

2021-10-05T14:48:34Z

8/17/11

Mechanical Engineering

null

['https://hdl.handle.net/2152/88385', 'http://dx.doi.org/10.26153/tsw/15324']

eng

2011 International Solid Freeform Fabrication Symposium

Open

['golf club head', 'electron beam melting (EBM)', 'additive manufacturing (AM)', 'functionally graded porosity (FGP)']

Optimal Design of a Golf Club using Functionally Graded Porosity

Conference paper

https://repositories.lib.utexas.edu//bitstreams/dbbda56b-55e4-446a-bbf8-3da786ca64ae/download

University of Texas at Austin

The current work portrays a new concept of designing and manufacturing golf club heads with functionally graded porosity (FGP) by means of electron beam melting® (EBM®). In light of the advancement of additive manufacturing (AM) technologies and the consequent wide spread applications in the aerospace, automotive, and biomedical industries, the current work discusses a new application in sport technologies; for example, in the golf industry. EBM® makes it possible to print the designed porosity within a golf club head, to reduce the weight and optimize performance. The focus is to design the golf club head with FGP to improve performance and reduce weight. The dynamic properties of porous materials are investigated theoretically. The porosity in the club head was analyzed numerically by simulating the impact between the club head and a steel ball in order to determine the coefficient of restitution (COR) of the club head. The simulation’s parameters are in compliance with the U.S Golf Association’s (USGA) test procedure for measuring COR.

null

['Cao, Xiaoqing', 'Ayalew, Beshah']

2021-10-18T21:53:03Z

2014

Mechanical Engineering

null

https://hdl.handle.net/2152/89263

eng

2014 International Solid Freeform Fabrication Symposium

Open

['laser-aided powder deposition', 'melting interface tracking', 'optimization']

Optimal Melting Interface Tracking in Laser-Aided Powder Deposition Processes

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9744852e-6c3b-4b92-a1ce-8c3b7c30e0e5/download

University of Texas at Austin

This paper presents a systematic control inputs optimization method for melting interface tracking in laser-aided powder deposition (LAPD) processes. Using a proposed interface approximation and a coordinate system moving with the laser source, and adopting the enhanced thermal conductivity method, the process model is first reduced to a set of coupled partial differential equations (PDEs) in fixed spatial domains. Then, the control problem of achieving process target properties is formulated as one of optimizing the control inputs to track a prescribed melting interface which is approximated from required process target parameters. This proposed optimization scheme is solved by the adjoint-based gradient method for which an algorithm is provided. A weighting scheme is also proposed to overcome feasibility issues with poor interface specifications and still achieve improved tracking of target parameters. The proposed scheme is illustrated through a simulation-based case study on a laser cladding process.

null

['Miyanaji, Hadi', 'Zhang, Shanshan', 'Lassell, Austin', 'Zandinejad, Amir Ali', 'Yang, Li']

2021-10-21T20:58:01Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89446

eng

2015 International Solid Freeform Fabrication Symposium

Open

['3D printing', 'binder jetting process', 'green parts', 'sintering']

Optimal Process Parameters for 3D Printing of Dental Porcelain Structures

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2c89f960-629c-465b-93bd-136187cfdbbf/download

University of Texas at Austin

Dental porcelain material is a typical glass ceramic material that is widely used in dental restoration applications. However, there still exists limited knowledge about the fabrication of this type of materials using binder jetting additive manufacturing process. There are several important factors such as saturation level, power level, drying time as well as spread speed, which would potentially affect the accuracy and strength of the printed parts before and after sintering. Therefore, in this research an extensive experimental study was performed to obtain the optimal process parameters for the dental porcelain materials fabricated via ExOne binder jetting system. The results also provide general printing guidelines for the fabrication of glass ceramic materials.

null

['Dzogbewu, T.C.', 'Yadroitsev, I.', 'Krakhmalev, P.', 'Yadroitsava, I.', 'Du Plessis, A.']

2021-11-02T13:47:30Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89801

eng

2017 International Solid Freeform Fabrication Symposium

Open

['process parameters', 'in situ', 'Ti15Mo', 'laser powder bed fusion']

Optimal Process Parameters for In Situ Alloyed Ti15Mo Structures by Laser Powder Bed Fusion

Conference paper

https://repositories.lib.utexas.edu//bitstreams/629d91f2-8c81-4f4d-b117-734dc1762954/download

University of Texas at Austin

Powder Bed Fusion (PBF) is a manufacturing method with the advantage that it can produce objects of complex geometry. Additionally, it opens great opportunities to synthesize new materials from elemental powder using an in situ alloying approach. Potential of the in situ PBF alloying approach is nevertheless not well understood due to lack of experimental knowledge and information on the influence of process parameters on the microstructure, homogeneity and properties of the final materials. This investigation is focused on Ti15Mo alloy that was chosen as a promising β-type alloy for biomedical applications due to low Young’s modulus, close to the mechanical properties of bones. Geometrical characteristics of single tracks were investigated at a wide range of laser powers and scanning speeds. Threshold of enthalpy ratio to transition from conduction to keyhole mode was found. To study the distributions of molybdenum in Ti matrix, X-ray nanoCT scans and SEM EDS were performed. Effects of hatch distance and scanning strategy on the layer surface morphology were investigated. Microstructure and mechanical properties of as-built specimens were analyzed. Illustrated effects of each process parameter on the synthesized material is paramount to successful manufacturing of advanced implants with mechanical properties close to bones.

null

['Ghazanfari, Amir', 'Li, Wenbin', 'Leu, Ming C.', 'Landers, Robert G.']

2021-10-21T18:28:54Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89420

eng

2015 International Solid Freeform Fabrication Symposium

Open

['rastering orientation', 'freeform extrusion fabrication', 'horizontal staircase effect']

Optimal Rastering Orientation in Freeform Extrusion Fabrication Processes

Conference paper

https://repositories.lib.utexas.edu//bitstreams/24ec35db-5e3f-4d69-a408-02e06324aca9/download

University of Texas at Austin

Many researchers have tried to optimize the build direction of additively manufactured parts to minimize the vertical staircase effect. However, the horizontal staircase effect should also be considered when fully dense parts are to be fabricated. In this paper, part inaccuracy due to the horizontal staircase effect is considered in order to determine the optimal rastering orientation in building the part. An algorithm is developed to estimate this inaccuracy and a technique is proposed to minimize it. The effect of rastering orientation on staircase errors is examined, and the particle swarm optimization method is used to determine the optimum rastering angle that leads to minimum errors for each layer. Several case studies are considered where the staircase errors are calculated with and without optimizing the rastering orientation. The results show that the errors can be reduced considerably when using the optimal rastering orientation. To verify the analytical results, parts are fabricated using a freeform extrusion fabrication process at various angles and the errors are compared.

null

['Subedi, Subodh C.', 'Thoma, Dan J.', 'Suresh, Krishnan']

2023-01-26T15:34:53Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117318', 'http://dx.doi.org/10.26153/tsw/44199']

eng

2022 International Solid Freeform Fabrication Symposium

Open

LPBF

Optimal Truss-Type Supports for Minimal Part Distortion in LPBF

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a2390f25-2ad7-43a9-a743-ebc981c7cd24/download

null

Eﬃcient transfer of heat to the build plate is important for part printability in laser powder bed fusion (LPBF). Support structures provide pathways for heat dissipation from the melt pool to the build plate. Truss-type supports have been proposed for better thermal management in LPBF since they are easy to analyze, optimize and post-process. In this paper, we consider thermo-elastic LBPF simulations, where a part and corresponding truss- type support are progressively coupled during the build process. Transient thermal FEA is performed as each layer is built to obtain temperature proﬁles. Thermal and structural equivalent static loads are obtained from the transient results, which are accumulated to compute aggregate structural equivalent static loads (ASESL). Structural deformation of coupled systems involving part and truss-type supports is also computed after each layer- wise built. Finally, cross-sectional areas of truss-type supports are optimized using ASESL to minimize structural deformation. Optimized supports show a signiﬁcant reduction in part deformation compared to un-optimized supports. Numerical results are presented to demonstrate the merits of the proposed method.

null

['Vaithilingam, Jayasheelan', 'Laoboonmee, Kasidis', 'Saleh, Ehab', 'Hague, Richard J.M.', 'Wildman, Ricky D.', 'Tuck, Christopher J.']

2021-11-01T22:23:35Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89780

eng

2016 International Solid Freeform Fabrication Symposium

Open

['substrate angles', 'dielectric substrate', 'multi-functional parts', 'multi-material parts', 'optimization', '3D inkjet printing']

Optimisation of Substrate Angles for Three Dimensional Inkjet Printing of Multi-Functional and Multi-Material Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9a7e251e-b95c-40c9-b24a-0c57ceebd1e7/download

University of Texas at Austin

Three dimensional (3D) inkjet printing of multiple materials is being explored widely to fabricate multi-functional parts such as the printing of strain gauges and heating elements embedded within a component. Although dielectrics and conductive materials can be inkjet-printed together, there is a difference in their layer thicknesses. Inkjet printed conductive materials require sintering at temperatures of around 150°C to form a conductive network. Exposing the dielectric materials which may be sensitive to prolonged heat exposure could affect their material properties. Hence, optimisation of conductive routes within the structural material is essential. It is envisaged that printing of structural materials at an angle to a certain height/layers and then printing a few layers (~ 10 layers) of conductive material on to the top surface will enable faster fabrication and reduced exposure of the dielectric material to heat. To compliment this aim, in this study, dielectric substrates were printed at different angles and the conductivity of the tracks were assessed. Surface morphology of the printed tracks showed misplacement of droplets for angles above 15° due to the influence of print height. The printed tracks remained conductive up to 65°; however above 50°, the tracks were highly resistive (> 150KΩ). The optimal angle to obtain conductive tracks with the highest print resolution was 15° and it was greatly influenced by the print height. Further study is required to optimise the substrate angle by using a constant print height and varying the slope length.

null

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

2021-09-28T17:49:28Z

9/10/08

Mechanical Engineering

null

['https://hdl.handle.net/2152/88135', 'http://dx.doi.org/10.26153/tsw/15076']

eng

2008 International Solid Freeform Fabrication Symposium

Open

['anionic polymerization', 'caprolactam', 'polyamide 6', 'inkjetting']

Optimised Polymerization Conditions for Inkjetting of Caprolactam to Produce Polyamide Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a86f31b0-fa1d-4623-b8a5-5af5b5a78939/download

University of Texas at Austin

Rapid Manufacturing (RM) techniques have been developed to shorten the processing cycle, and lead to efficient production of ready-to-use complex items. This project aims to manufacture three dimensional parts, directly from monomer, using a 3D Printing process based on ink-jet printing technology. A fast polymerization and high monomer conversion are essential. This work describes conditions for the rapid anionic polymerization of caprolactam after inkjetting to produce polyamide (nylon 6) parts. The effect of polymerization temperature and different catalyst/initiator types and concentrations on the rate of reaction were studied. Results show that, although increasing polymerization temperature results in quicker polymerization, the highest polymerization rate is achievable with 0.38g of sodium hydride and 320µl of N-acetylcaprolactam.

null

['ONUH, S.O.', 'HON, K.K.B.']

2018-12-07T16:13:27Z

1997

Mechanical Engineering

doi:10.15781/T24747B9Z

http://hdl.handle.net/2152/71445

eng

1997 International Solid Freeform Fabrication Symposium

Open

['RPT', 'Stereolithography']

Optimising Build Parameters and Hatch Style for Part Accuracy in Stereolithography

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f4abe751-e6b1-4a58-b0d7-ae5d3952b577/download

null

A detailed study of the effects of layer thickness, hatch spacing, hatch overcure depth, and hatch fill cure depth on the quality of the StereoLithography (SL) product was carried out using acrylic based resin. Taguchi Method was used for analysing all experimental results. The ANOVA and the Signal-to-noise ratio (SIN) results were used to select the optimum parameters and the appropriate factor levels for further experiments. A new hatch styIe with an optimum layer thickness is proposed for the build process with minimum geometrical distortion.

null

['Richards, I.P.F.', 'Garabet, T.M.N.', 'Bitar, I.S.', 'Salmon, F.M.']

2021-11-02T19:49:10Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89881

eng

2017 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'laser sintering', 'desktop-laser sintering', 'thermoplastic polyurethane', 'powder characterisation', 'mechanical properties']

Optimising Thermoplastic Polyurethane for Desktop Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0ca12e4b-3034-4b84-922f-4c353a0f2388/download

University of Texas at Austin

Laser Sintering (LS) is an industrially relevant Additive Manufacturing method that has become more accessible since the introduction of commercially available desktop-LS systems. However, useable materials are currently limited to several grades of nylon, and so the aim of this study was to optimise an unknown, novel material for use in desktop-LS. A grade of thermoplastic polyurethane (UNEXTPU) was analysed to determine thermal properties, particle characteristics and bulk powder flow efficiency. To facilitate laser absorption at 445nm, a carbon additive (graphite) was added to UNEXTPU; the addition of graphite also significantly improved flow efficiency. UNEXTPU was successfully processed on a desktop-LS system, and mechanical testing found that it possesses properties comparable to industrial grade thermoplastic polyurethanes (Elongation at Break: 139%, Tensile Modulus: 48.7Mpa, Ultimate Tensile Strength: 7.9Mpa, Shore Hardness: 75). Bulk powder flow efficiency and mechanical properties were retained in twice recycled powder. This research has established a new viable elastomeric material for use in desktop-LS.

null

['Brackett, D.', 'Panesar, A.', 'Ashcroft, I.', 'Wildman, R.', 'Hague, R.']

2021-10-11T21:32:37Z

8/16/13

Mechanical Engineering

null

['https://hdl.handle.net/2152/88650', 'http://dx.doi.org/10.26153/tsw/15584']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['multi-material 3D printing', 'additive manufacturing', 'topology optimization', 'design analysis', 'optimization', 'active internal systems']

An Optimization Based Design Framework for Multi-Functional 3D Printing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/97f045cd-b91f-4d18-8739-f5976cce77df/download

University of Texas at Austin

This work investigates design analysis and optimization methods for the integration of active internal systems into a component for manufacture using multi-material 3D printing processes. This enables efficient design of optimal multifunctional components that exploit the design freedoms of additive manufacturing (AM). The main contributions of this paper are in two areas: 1) the automated placement and routing of electrical systems within the component volume and, 2) the accommodation of the effect of this system integration on the structural response of the part through structural topology optimization (TO). A novel voxel modeling approach was used to facilitate design flexibility and to allow direct mapping to the 3D printer jetting nozzles.

null

Levy, Richard A.

2018-05-03T17:59:57Z

1993

Mechanical Engineering

doi:10.15781/T2M32NT3H

http://hdl.handle.net/2152/65048

eng

1993 International Solid Freeform Fabrication Symposium

Open

['Craniofacial Imaging and Modeling', 'CT']

Optimization of 2D CT Data Sets for Three-Dimensional

Conference paper

https://repositories.lib.utexas.edu//bitstreams/db47963a-4cf7-4a16-8c5e-9e0d301008d9/download

null

Computer-generated anatomic modeling using radiologic data is a well-known entity. Currently, state of the art 3D modeling systems lack the variable thresholding, user interactive, capabilities of 3D imaging software.1 We investigated clinical parameters - cr scan plane, 2D filter algorithm, surrounding medium - and tested a simple mathematical thresholding algorithm based upon experimentation with a cr phantom, to evaluate a semiautomated approach to 3D craniofacial imaging and model generation. (Figure 1)

null

['Borstell, D.', 'Georg, M.-C.']

2021-12-01T21:27:43Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90619', 'http://dx.doi.org/10.26153/tsw/17538']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['design for additive manufacturing', 'gear assembly', 'worm gear', 'double bass']

Optimization of a Worm Gear Assembly Design for Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c9144d42-e32f-45d5-a087-debdf15c8f55/download

University of Texas at Austin

Worm gears are widely used to transmit power at predominantly low speeds and highspeed ratios. Their self-locking characteristic makes them unique to many drive applications. Industrial power requirements are causing forces and tensions mostly prohibiting thermoplastic materials in worm gear drive trains. Double basses are tuned using a worm gear assembly made from machined steel and brass or cast bronze. Neglectable power requirements, few hours of operation, esthetic expectations and the classic luthier’s approach to making such an instrument by hand have excluded the double basses’ tuning assembly from all engineering approaches regarding optimal design, efficiency and costs. Manufacturing the traditionally designed double bass worm gear assembly using Additive manufacturing processes requires the application of general design rules and the rules of Design for Additive Manufacturing (DFAM) resulting in an optimized gear assembly regarding weight, costs and design properties.

null

['Fieger, T.', 'Nugara, D.', 'Huebner, J.', 'Witt, G.']

2021-11-02T18:39:08Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89864

eng

2017 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'laser sinitering', 'adhesives', 'bonding agent', 'assembly', 'norms and standards']

Optimization of Adhesively Joined Laser-Sintered Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5791c8b8-adf9-4b91-8154-ddf54097c0e5/download

University of Texas at Austin

As additive manufacturing technologies are advancing in quality and economic feasibility, joining and assembly is becoming increasingly important for industrial users. In this study, the performance of four adhesives for polyamide 12 specimens is analyzed. Testing of bonding relevant factors, such as the surface energy of the solid substrates, is conducted. Tensile shear tests of plain polyamide 12 specimens glued together, show an early adhesive failure of the joint. To increase the polar bonding forces and the surface energy of the solid substrate, pretreatments such as atmospheric plasma, chemical, corona and flame treatment are applied. An increase up to 81% of the original binding strength can be achieved with flame treatment. As an alternative to increase the bonding strength of the joints, the effects of design changes of the bonding area are looked at. The research shows that micro tubes on the surface of a substrate can increase the bonding strength up to 49%. A summary of the impact of all pretreatments and design changes is given and the suitability of each application is assessed.

null

['Peng, Hao', 'Ghasri-Khouzani, Morteza', 'Gong, Shan', 'Attardo, Ross', 'Ostiguy, Pierre', 'Aboud Gatrell, Bernice', 'Budzinski, Joseph', 'Tomonto, Charles', 'Neidig, Joel', 'Shankar, M. Ravi', 'Billo, Richard', 'Go, David B.', 'Hoelzle, David']

2021-11-02T20:06:57Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89883

eng

2017 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'DMLS', 'optimization', 'build orientation', 'thermal distortion', 'thermal stress', 'support structure']

Optimization of Build Orientation for Minimum Thermal Distortion in DMLS Metallic Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c07b1f92-77de-4b5a-9108-ae96f86c8f7a/download

University of Texas at Austin

The additive manufacturing (AM) process direct metal laser sintering (DMLS) can quickly produce complex parts. However, thermal stress in DMLS may induce thermal distortion and cause build failure. This manuscript presents an optimization algorithm for the build orientation in DMLS to minimize thermal distortion. The algorithm is built on the foundation of two coupled thermal and thermo-mechanical models developed in our previous work. The DIRECT search method and a universal objective function for thermal distortion were used. Constraints were included to rule out build orientations resulting in overheating or excessive oxidation. The optimization algorithm was tested on a rectangular bar and a complex, contoured part. Both parts were printed using an EOS M290 machine, and measured by a coordinate measuring machine. In comparison to build orientations chosen by two novice operators, the optimized build orientations gave significant reduction in the thermal distortion and number of print trials before print success.

null

['Tariq, Usman', 'Joy, Ranjit', 'Wu, Sung-Heng', 'Arif Mahmood, Muhammad', 'Woodworth, Michael M.', 'Liou, Frank']

2024-03-26T20:06:25Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124386', 'https://doi.org/10.26153/tsw/50994']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['metal additive manufacturing', 'finite element analysis', 'computational time', 'directed energy deposition', 'residual stress']

OPTIMIZATION OF COMPUTATIONAL TIME FOR DIGITAL TWIN DATABASE IN DIRECTED ENERGY DEPOSITION FOR RESIDUAL STRESSES

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0f998361-54b5-4584-ba7a-b2b6a0e703b3/download

University of Texas at Austin

Metal Additive Manufacturing (MAM) has experienced rapid growth and demonstrated its cost-effectiveness in the production of high-quality products. However, MAM processes introduce significant thermal gradients that result in the formation of residual stresses and distortions in the final parts. Finite Element Analysis (FEA) is a valuable tool for predicting residual stresses, but it requires substantial computational power. This study aims to reduce computational time by incorporating a thermo-mechanical model specifically designed for the Directed Energy Deposition (DED) process using Ti6Al4V. This model predicts the thermal history and subsequent residual stresses in the deposited material. Various FEA methods, including “chunk”, layer, and conventional methods are examined, providing a comparative analysis of computational cost and numerical accuracy. These findings contribute towards the realization of a digital twin database, where the incorporation of efficient and accurate FEA models can optimize part quality and strength while reducing computational time.

null

['Chen, Yu', 'Vastola, Guglielmo', 'Zhang, Yong Wei']

2021-11-15T21:10:24Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90273', 'http://dx.doi.org/10.26153/tsw/17194']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['inert gas flow', 'chamber', 'computational fluid dynamics', 'laser powder bed fusion', 'CFD', 'L-PBF']

Optimization of Inert Gas Flow Inside Laser Powder Bed Fusion Chamber with Computational Fluid Dynamics

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d9152b01-255b-4d83-9888-a3e9ac9ef01e/download

University of Texas at Austin

It is crucial to maintain a uniform and fast enough inert gas flow inside build chamber to obtain high-quality final products (e.g. low porosity) without oxidation. The current study investigated the behaviors of the inert gas flow inside a chamber with CFD simulations, as well as its evaluation and optimization. The gas flow pattern inside the chamber was evaluated in terms of the uniformity of velocity across the build plate. It was shown that the gas channels and locations of inlet openings significantly affected the flow inside the chamber. So the design of gas channels/inlets and flow rates was carefully adjusted to generate uniform gas flow across the chamber to remove emissions from the melt pool efficiently. Furthermore, the re-circulation of emission inside chamber was significantly reduced to keep the chamber walls clean and minimize the damage to the optical surface. In conclusion, CFD benefits in improving quality of products and reducing life-cycle cost for laser powder-bed fusion process (L-PBF).

null

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

2023-03-28T19:24:34Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117668', 'http://dx.doi.org/10.26153/tsw/44547']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Laser Powder Bed Fusion', 'neural networks', 'machine learning', 'SS316L']

Optimization of Laser Process Parameters Using Machine Learning Algorithms and Performance Comparison

Conference paper

https://repositories.lib.utexas.edu//bitstreams/24687bb1-b94f-4e92-9fd1-ef48f53c8877/download

null

Laser powder bed fusion (L-PBF) can be used to produce near net-shaped functional metal components. Despite offering high flexibility in producing components with intricate geometries, L-PBF has many constraints in terms of controllability and repeatability because of large number of processing parameters. There is a need for a robust computational model which can predict the properties of L-PBF parts using a wide range of processing parameters. In this work, several Machine learning-based algorithms like Random Forest, k Nearest Neighbors, XGBOOST, Support Vector Machine (SVM), and Deep Neural Networks are used to model the property- processing parameters relation for SS 316L samples prepared by LPBF. Laser power, scan speed, hatch spacing, scan strategy, volumetric energy density, and density are used as the input to these models. The developed model is then used to predict and analyze the surface roughness of as- fabricated SS 316L specimens. The prediction and experimental results are compared for the above-mentioned models to evaluate the capabilities and accuracy of each model.

null

['Theeda, S.', 'Ravichander, B.B.', 'Jagdale, S.H.', 'Kumar, G.']

2023-04-03T17:45:39Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117729', 'http://dx.doi.org/10.26153/tsw/44608']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Laser Powder Bed Fusion', 'Neural Networks', 'Machine Learning', 'SS316L']

Optimization of Laser Process Parameters Using Machine Learning Algorithms and Performance Comparison

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9282689e-03f2-47da-abd5-30d5d236e787/download

null

Laser powder bed fusion (L-PBF) can be used to produce near net-shaped functional metal components. Despite offering high flexibility in producing components with intricate geometries, L-PBF has many constraints in terms of controllability and repeatability because of large number of processing parameters. There is a need for a robust computational model which can predict the properties of L-PBF parts using a wide range of processing parameters. In this work, several Machine learning-based algorithms like Random Forest, k Nearest Neighbors, XGBOOST, Support Vector Machine (SVM), and Deep Neural Networks are used to model the property- processing parameters relation for SS 316L samples prepared by LPBF. Laser power, scan speed, hatch spacing, scan strategy, volumetric energy density, and density are used as the input to these models. The developed model is then used to predict and analyze the surface roughness of as- fabricated SS 316L specimens. The prediction and experimental results are compared for the above-mentioned models to evaluate the capabilities and accuracy of each model.

null

['Kim, Dong Sung', 'Thompson, Steven', 'Grunlan, Melissa', 'Tai, Bruce L.']

2021-10-28T14:57:02Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89658

eng

2016 International Solid Freeform Fabrication Symposium

Open

['low one-photon polymerization', 'hydrostatic 3D printing', 'silicone material', 'optimization']

Optimization of Low One-Photon Polymerization for Hydrostatic 3D Printing of Silicone Material

Conference paper

https://repositories.lib.utexas.edu//bitstreams/261fca2d-e113-466a-b7e5-19015a5cf652/download

University of Texas at Austin

This study investigated the parameter optimization of low one-photon polymerization in hydrostatic 3D printing (H3P). H3P produces 3D structures in a hydrostatic condition with minimum or no physical supports, used particularly for soft materials that typically require substantial supports to hold the position and shape in conventional 3D printing methods. H3P allows for “in-liquid” polymerization to happen by low one-photon polymerization (LOPP) to cure the silicone at the focusing spot inside of the resin. With the selected UV-curable silicone, different wavelengths, light intensities, and exposure times were investigated to achieve an ideal LOPP. The ideal LOPP should have a wide time window to precisely control the polymerization size and produce a consistent geometry. This is largely dependent on the light wavelength and then the intensity. In this study, the wavelength of 387 nm with the absorbance rate of 0.008 was found the optimal setting for the selected silicone among 365 nm (0.051 absorbance rate) and 405 nm (nearly 0 absorbance rate) wavelengths. The results showed that the parameters for LOPP are very selective.

null

['Yan, Jingyuan', 'Battiato, Ilenia', 'Fadel, Georges M.']

2021-10-18T21:47:41Z

2014

Mechanical Engineering

null

https://hdl.handle.net/2152/89260

eng

2014 International Solid Freeform Fabrication Symposium

Open

['Laser Engineered Net Shaping', 'Direct Metal Deposition', 'in-flight melting', 'multi-materials']

Optimization of Multi-Materials In-Flight Melting in Laser Engineered Net Shaping (LENS) Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/8eb1000e-65cf-422c-b12e-0b323e825808/download

University of Texas at Austin

A heterogeneous object has potentially many advantages and in many cases can realize appearance and/or functionality that homogeneous objects cannot achieve. LENSTM, a Direct Metal Deposition process, is one technology with the potential to fabricate heterogeneous objects. In-flight melting provides an advantageous condition for better mixing of multiple materials with different properties, thus critical for fabricating heterogeneous objects. In this study, a multi-materials in-flight melting model of the LENS process is developed for the cases of single and multiple particles jets. The impact of in-flight particles melting as well as substrate melting on materials mixing is investigated. An optimization method is proposed for the LENS fabrication of heterogeneous objects based on the concurrent melting of particles and substrate. A cermet composite material fabrication test case is utilized to demonstrate the applicability of the method. Inconel 718 powders and alumina ceramic powders are used as building materials in the test case. A group of optimized process parameters are provided: using a 320 W, 600 μm spot diameter laser moving at 10 mm/s, the injection angles are 20°, the injection velocities are 1 m/s, the material feeding rates are 0.5 g/min, the particle diameters are 20 μm, and the nozzle diameters are 0.7 mm for both materials. Moreover, the material with a lower melting point should be injected in the front of the laser moving direction, while the material with a higher melting point should be injected from the rear.

null

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

2023-01-19T17:48:01Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117251', 'http://dx.doi.org/10.26153/tsw/44132']

eng

2022 International Solid Freeform Fabrication Symposium

Open

adhesion

Optimization of penetration depth and powder layer thickness for proper interlayer adhesion in polymer laser sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ef8501fc-dc22-4f8e-a8c7-ac71fb111fba/download

null

In laser sintering, the melt pool depth relative to the powder layer thickness is the main factor influencing interlayer adhesion strength. The melt pool depth is closely related to the amount of laser energy and its penetration depth. Previous studies have shown that using a near-infrared laser and an additive agent that absorbs its light allows for a wide range of penetration depth control. This research focuses on the optimization of the powder layer thickness and penetration depth to achieve appropriate interlayer adhesion. To determine the optimal amount of laser energy, the relationship between the amount of laser energy and part density for each layer pitch and penetration depth was determined. The relationship between the amount of energy supplied normalized by the penetration depth and part density was consistent regardless of the penetration depth of the powder material. The adhesion strength of specimens prepared using different optimal amounts of energy to maximize part density was evaluated. Based on this evaluation, layer thickness normalized by penetration depth is the dominant factor influencing interlayer adhesion strength.

null

['Karapatis, N.P.', 'Egger, G.', 'Gygax, P.E.', 'Glardon, R,']

2019-03-12T17:05:57Z

1999

Mechanical Engineering

null

['https://hdl.handle.net/2152/73604', 'http://dx.doi.org/10.26153/tsw/746']

eng

1999 International Solid Freeform Fabrication Symposium

Open

['SLS', 'polymer']

Optimization of Powder Layer Density in Selective Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/badbcef3-9fa5-4b0a-bb38-34299dcaedae/download

null

An important parameter for the overall quality of SLS parts is the density of powder layers before sintering. Previous studies have shownthatthe control of powder particle shape and size distribution can increase the density of non-packed powder beds. However, these studies concerned beds several orders of magnitude larger than the SLS layers. The purpose ofthis study. is to determine if,and to what extent, the density of thin powder layers can be ineteased. Experiments show that the density of thin layers increases from 53% to 63% when adding 30% fine powder to the coarse powder,/with a coarse-to-fine ratio of 1:10. Compared with the bulk experiments, this density improvement method is less efficient, because the particles do not arrange as efficiently, and the wall effects can become predominant.

null

['Ashby, Kathryn', 'Fieldman, Zack', 'Kenney, Pat', 'Rockstroh, Todd']

2021-10-19T15:17:33Z

2014

Mechanical Engineering

null

https://hdl.handle.net/2152/89295

eng

2014 International Solid Freeform Fabrication Symposium

Open

['direct metal laser melting', 'process parameters', 'reentrant build geometry', 'reentrant surface finish']

Optimization of Process Parameters for Reentrant Surfaces in Direct Metal Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e8f7e7b4-e6c6-40f1-95ad-fda053da2505/download

University of Texas at Austin

One of the key factors for development and optimization of direct metal laser melting (DMLM) is the analysis of process parameters on reentrant build geometry and surface finish. Recent studies have focused on the optimization of standard build parameters with only minor emphasis on reentrant geometries. Parameters that are not optimized often contribute to poor surface finish, difficult to remove supports, and failed-to-build geometries of reentrant surfaces that limit the capabilities of DMLM. Through the analysis of multiple studies with varying process parameters and input scan path geometry, open loop methods for creation and control of reentrant build geometries are assessed and presented.

null

['Leu, Ming C.', 'Pattnaik, Shashwatashish', 'Hilmas, Gregory E.']

2021-09-30T18:34:38Z

2010

Mechanical Engineering

null

['https://hdl.handle.net/2152/88273', 'http://dx.doi.org/10.26153/tsw/15214']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['Selective Laser Sintering', 'zirconium diboride parts', 'optimization', 'ultra-high temperature applications']

Optimization of Selective Laser Sintering Process for Fabrication of Zirconium Diboride Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f6f45122-5955-458a-92e4-55635d7e62da/download

University of Texas at Austin

Selective Laser Sintering (SLS) was investigated to fabricate Zirconium Diboride (ZrB2) parts for ultra-high temperature applications. Experiments were conducted to determine values of SLS process parameters (laser power, scan speed, line spacing, and layer thickness) that can be used to build ZrB2 parts with high integrity and sharp geometrical features. A sacrificial plate with a proper number of layers (determined from experimentation) separated from the main part was built in order to reduce thermal gradients when building the main part. The sacrificial plate was found to assist in eliminating cracks in the bottom of the main part. The fabricated green parts then went through post processing steps including binder burnout and sintering at proper temperature schedules, to remove the binder and sinter the ZrB2 particles. The test bars after sintering had an average relative density of 87% and an average flexural strength of 250 MPa.

null

['Ghanekar, Amol S.', 'Crawford, Richard H.', 'Watson, Douglas']

2019-11-20T17:08:24Z

2003

Mechanical Engineering

null

['https://hdl.handle.net/2152/78485', 'http://dx.doi.org/10.26153/tsw/5570']

eng

2003 International Solid Freeform Fabrication Symposium

Open

SLS Process

Optimization of SLS Process Parameters Using D-Optimality

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2817d846-20ce-4633-8fd0-f4a55af79692/download

null

Solid Freeform Fabrication (SFF) refers to a group of processes that manufacture parts of arbitrarily complex geometry without tooling. Currently, the operation of most SFF machines requires skilled operators with expertise in choosing process parameters in ordered to achieve the desired part quality. Thus, the “push-button 3D hardcopy” promise of SFF has yet to be realized. This paper presents a framework for selecting optimal process parameter values automatically for the selective laser sintering (SLS) process. The research described considered five process parameters that are important for the SLS process. To achieve quality measures from the five process parameters, optimization is inevitable. The method optimizes these process parameters of SLS with respect to a set of desired quality measures, based on user input of the relative importance of each of the quality measures. The basis for the framework is the so-called Doptimality criterion applied to a series of factorial experiments that capture empirically the relationships between the process parameters and part quality measures. The framework is implemented in MINITAB™ and a macro is used to perform the optimization.

null

['Teufelhart, S.', 'Reinhart, G.']

2021-10-06T21:19:25Z

8/15/12

Mechanical Engineering

null

['https://hdl.handle.net/2152/88447', 'http://dx.doi.org/10.26153/tsw/15384']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['Additive Layer Manufacturing', 'lattice structures', 'strut diameters', 'stress directions']

Optimization of Strut Diameters in Lattice Structures

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5f8f6d4e-22e9-44c1-b6ef-60a4dad3dfa7/download

University of Texas at Austin

Additive manufactured lattice structures show a high potential for lightweight design. Currently, these structures have a periodical build-up, which leads to disadvantageous stress states. On the one hand, unfavorable bending loads on the single struts appear. This can be avoided by an adaption of the course of the structure to the main stress directions inside the part. On the other hand, different stress values are appearing inside the single struts. Therefore, a procedure for the optimization of the struts diameters is presented. Thus, it becomes possible to achieve equal stresses in the whole structure and gain a better lightweight performance.

null

['Krol, T.A.', 'Zach, F.', 'Seidel, C.']

2021-10-06T21:15:54Z

8/15/12

Mechanical Engineering

null

['https://hdl.handle.net/2152/88446', 'http://dx.doi.org/10.26153/tsw/15383']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['metal-based additive manufacturing', 'support structures', 'finite element models']

Optimization of Supports in Metal-Based Additive Manufacturing by Means of Finite Element Models

Conference paper

https://repositories.lib.utexas.edu//bitstreams/668d7730-ab1b-4e54-87d4-0006d38fc64c/download

University of Texas at Austin

Metal-based additive manufacturing processes require a supporting of overhanging part areas during the powder solidification e. g. for improving the heat dissipation to the substrate. Technology users nowadays strive to reduce support areas due to economical aspects, while simultaneously enhancing the process stability by maximizing the support stiffness. For the simplification and acceleration of this support design procedure, the presented work describes a methodology for optimizing support structures by means of finite element models. Thereby, the main approaches are covering a fractal adaptation of the support layout and an optimization of block supports depending on the calculation results. The presented methods were applied by using experimental components.

null

['Mukhametkaliyev, T.M.', 'Ferrucci, M.', 'Pavan, M.', 'Villanueva, M.C.', 'Craeghs, T.', 'Claeys, C.', 'Deckers, E.', 'Desmet, W.']

2021-11-30T20:14:33Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90533', 'http://dx.doi.org/10.26153/tsw/17452']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'laser sintering', 'vibro-acoustic metamaterial', 'ED mapping', 'up-skin and down-skin scanning strategy', 'scan pattern', 'computer tomography', 'optimization']

Optimization of the Additive Manufacturing Process for Geometrically Complex Vibro-Acoustic Metamaterials

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3f0558a7-8fde-4be8-9b52-b4527ce51f1a/download

University of Texas at Austin

A study performed at KU Leuven provided a proof-of-concept of vibro-acoustic locally resonant meta-materials manufactured with Laser Sintering (LS). However, the geometry and material properties of the manufactured parts deviated from their nominal (specified) values, resulting in differences in resonant frequencies of the locally added resonators and a deviation from their predicted vibro-acoustic performance. In this work, the fabrication of locally resonant vibroacoustic metamaterials was improved through a holistic engineering approach, resulting in an improved vibro-acoustic performance. It is shown that unequal energy density distribution within the printing layers is one of the main causes of deviations.

null

['Brown-Moore, Tosh Kāneala', 'Balaji, Srivatsan', 'Lipton, Jeffrey']

2023-02-09T19:07:39Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117444', 'http://dx.doi.org/10.26153/tsw/44325']

eng

2022 International Solid Freeform Fabrication Symposium

Open

Ukraine

Optimizing 3D Printed Tourniquets for Immediate Aid in Ukraine

Conference paper

https://repositories.lib.utexas.edu//bitstreams/51e4f486-b942-4886-867b-122164499057/download

null

The outbreak of conflict in Ukraine has been met with a drastic increase in demand for medical devices like the COVID pandemic. Additive manufacturing enables the on-demand onsite manufacturing of medical devices, such as tourniquets, necessary to save lives in emergency situations where delivery isn’t an option. Here we show the relative performance of open-source 3D printed GLIA tourniquet components made from ABS and PETG and compare them to a commercially available combat application tourniquet (CAT). Using a variety of mechanical tests, our results demonstrate that tourniquet components printed with PETG are the best alternative to commercially available tourniquets in terms of cost and mechanical properties. We used this work to guide aid efforts for Ukraine through the Open-Source Medical Supply Organization.

null

['Thompson, David C.', 'Crawford, Richard H.']

2018-11-08T15:05:17Z

1995

Mechanical Engineering

doi:10.15781/T2MK65T8G

http://hdl.handle.net/2152/69882

eng

1995 International Solid Freeform Fabrication Symposium

Open

['SLS', 'SALD', 'Rapid prototyping']

Optimizing Part Quality with Orientation

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3f8062c8-0c2b-448c-b2fd-b6fcdcf560bb/download

null

The orientation of SFF-manufactured parts can have a significant effect on the quality of the parts, in both surface effects and strength. Currently, orientation is either ignored or set on the basis of experience. This paper takes some simple experiments and creates quantitative measures relating different aspects of part quality to orientation. This leads to several computational tools for optimizing the orientation of a part for manufacture with SLS or SALD on the basis of part strength, surface "aliasing" error, volumetric supports, and build time as an alternative to human experts.

null

['Asiabanpour, B.', 'Vejandla, D.T.', 'Novoa, C.', 'Jimenez, J.', 'Fischer, R.']

2021-09-28T18:25:13Z

9/18/09

Mechanical Engineering

null

['https://hdl.handle.net/2152/88146', 'http://dx.doi.org/10.26153/tsw/15087']

eng

2009 International Solid Freeform Fabrication Symposium

Open

['plasma cutting', 'regression model', 'desirability function', 'optimiization', 'experimental design', 'Rapid Manufacturing']

Optimizing the Quality of Parts Manufactured by the Automated Plasma Cutting Process Using Response Surface Methodology

Conference paper

https://repositories.lib.utexas.edu//bitstreams/010be919-80ed-41b8-8f9d-0c994df5e4e4/download

University of Texas at Austin

Automated plasma cutting is an effective process for building complex two-dimensional metallic parts in a short period of time. Because the plasma cutting machine has several factors or input variables to control (e.g., current, cutting speed, torch height) and a variety of part quality characteristics or response variables to satisfy (e.g., flatness, clean cut, bevel angle), it is very difficult to find an overall optimum machine setting. In this research, response surface methodology and desirability functions are used to simultaneously optimize 18 part quality characteristics. Final results identify an optimal machine configuration that facilitates the fabrication of parts with close-to-perfect quality for all responses considered.

null

['Novoa, C.', 'Flores, A.']

2021-11-18T01:23:03Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90391', 'http://dx.doi.org/10.26153/tsw/17312']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'AM', 'fused deposition modeling', 'FDM', 'polylactic acid', 'PLA', 'design of experiments', 'DOE']

Optimizing the Tensile Strength for 3D Printed PLA Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/197a26d4-fd9e-442d-89fa-f59e26d9121d/download

University of Texas at Austin

This research investigates on how extruder nozzle temperature, model infill rate (i.e. density) and number of shells affect the tensile strength of three-dimensional polylactic acid (PLA) products manufactured with the fused deposition model technology. Our goal is to enhance the quality of 3D printed products using the Makerbot Replicator. In the last thirty years, additive manufacturing has been increasingly commercialized, therefore, it is critical to understand properties of PLA products to broaden the use of 3D printing. We utilize a Universal Tensile Machine and Quality Engineering to comprehend tensile strength characteristics of PLA. Tensile strength tests are performed on PLA specimens to analyze their resistance to breakage. Statistical analysis of the experimental data collected shows that extruder temperature and model infill rate (i.e. density) affect tensile strength.

null

Laboratory for Freeform Fabrication and University of Texas at Austin

2023-01-19T17:34:45Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117249', 'http://dx.doi.org/10.26153/tsw/44130']

eng

2022 International Solid Freeform Fabrication Symposium

Open

Organizing Committee

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5e33398a-5278-4648-ba8b-1550a38eb505/download

null

['Borish, Michael', 'Roschli, Alex']

2021-12-06T23:43:59Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90721', 'http://dx.doi.org/10.26153/tsw/17640']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['slicing', 'on-demand slicing', 'additive manufacturing', 'sensor feedback', 'modeling feedback']

ORNL Slicer 2.0: Towards a New Slicing Paradigm

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1bb4ab61-d089-43bc-ab12-f955bd574e5a/download

University of Texas at Austin

One fundamental step of additive manufacturing is slicing. Slicing is the conversion of a 3D mesh to a set of layers containing all the necessary pathing to construct the object. The slicing process is typically viewed as one step in a sequential additive manufacturing workflow: an object is designed in CAD, sliced, and subsequent G-code is sent to the additive manufacturing system for construction. While successful, this workflow has limitations such as the utilization of sensor feedback for pathing alteration. To address limitations and better take advantage of opportunities resulting from the Industry 4.0 revolution, researchers at Oak Ridge National Laboratory developed a new slicer, ORNL Slicer 2.0. Slicer 2.0 was developed with the concept of “on-demand” slicing whereby the slicer takes a more active role in object construction. In this paper, we describe the fundamental design philosophy of this new approach as well as the Slicer 2.0 framework.

null

['Roschli, Alex', 'Messing, Andrew', 'Borish, Michael', 'Post, Brian K.', 'Love, Lonnie J.']

2021-11-02T20:32:16Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89889

eng

2017 International Solid Freeform Fabrication Symposium

Open

['ORNL Slicer 2', 'ORNL Slicer', 'tool path', 'additive manufacturing']

ORNL Slicer 2: A Novel Approach for Additive Manufacturing Tool Path Planning

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7031e942-8b88-4479-bcbb-b81b0c5001a5/download

University of Texas at Austin

ORNL Slicer is the first software designed to generate machine instructions, or tool paths, from CAD files for large-scale 3D printing of metals and polymers. The software was revolutionary because it allowed for slicing of models reaching 20 feet long, generating millions of lines of G-Code in seconds. The structure of the first ORNL Slicer had limitations in its framework, which has led to the development of ORNL Slicer 2. In the second version of the slicer, the process is modularized with individual layers being divided into regions, smarter infill patterns, and traversals are generated based upon stress, thermal, and other models. The new software has also been structured to allow for slicing and reslicing based on machine feedback during the printing process.

null

['Ahn, Dong-Gyu', 'Lee, Jun-Young', 'Yang, Dong-Yol']

2020-02-17T15:46:24Z

8/30/04

Mechanical Engineering

null

['https://hdl.handle.net/2152/80015', 'http://dx.doi.org/10.26153/tsw/7040']

eng

2004 International Solid Freeform Fabrication Symposium

Open

rapid prototyping

Orthopedic Surgery Planning Based on the Integration of Reverse Engineering and Rapid Prototyping

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b2404280-26e6-447d-9d38-eff43de19f25/download

null

This paper describes orthopedic surgical planning based on the integration of RE and RP. Using symmetrical characteristics of the human body, CAD data of the original bone without damages for the injured extent are generated from a mirror transformation of undamaged bone data for the uninjured extent. The physical model before the injury is manufactured from RP apparatus. Surgical planning, such as the selection of the proper implant, pre-forming of the implant, decision of fixation positions and incision sizes, etc., is determined by a physical simulation using the physical model. In order to examine the applicability and efficiency of surgical planning technology for orthopedics, various case studies, such as a proximal tibia plateau fracture, a distal tibia comminuted fracture and an iliac wing fracture of pelvis, are carried out. As a result of the examination, it has been shown that the orthopedic surgical planning based on the integration of RE and RP is an efficient surgical tool.

null

['Martínez-Magallanes, Mario', 'Cuan-Urquizo, Enrique', 'Ramirez-Cedillo, Erick', 'Roman-Flores, Armando']

2024-03-27T15:54:58Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124493', 'https://doi.org/10.26153/tsw/51101']

en

2023 International Solid Freeform Fabrication Symposium

Open

['fractal mechanical metamaterials', 'out-of-plane', 'Hibert curve', 'conformabiity', 'additive manufacturing', 'LCD SLA']

OUT-OF-PLANE MECHANICAL PROPERTIES OF ADDITIVELY MANUFACTURED FRACTAL REINFORCED STRUCTURES

Conference paper

https://repositories.lib.utexas.edu//bitstreams/61770751-c527-4527-a60a-53735f1634d5/download

University of Texas at Austin

Architected materials are an emergent kind of materials that gain their physical properties from their rationally designed micro-structures. They are normally conformed by regular unit-cells repetition, but other variations, such as hierarchal, aperiodic, and graded arrangements have also been explored as well. Here we propose an approach consisting of using fractal geometry to control the mechanical response of the metamaterials. We designed a set of 11 different arrangements based on the self-filling Hilbert fractal, the set consisted of 3 different iteration orders at 3 different matching relative densities, and two other graded arrangements. The samples were fabricated using a Micro-LCD 3D-printer and tested under out-of-plane loads. The test was performed using a texturometer with a spherical probe impregnated with red paint to characterize the conformability of the samples. Force and displacement were recorded to compare the mechanical response of the samples against the fractal parameters and obtain the structure-property relation.

null

['Li, Dian', 'Liu, Ruikai', 'Zhao, Xiayun']

2021-11-18T18:43:02Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90463', 'http://dx.doi.org/10.26153/tsw/17384']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['temperature measurement', 'in-situ', 'metallic additive manufacturing']

Overview of In-Situ Temperature Measurement for Metallic Additive Manufacturing: How and then What

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f34616d6-cf12-4b65-ac1f-188b68a0d35a/download

University of Texas at Austin

Additive manufacturing (AM) is important in industrial and economical domains but still lacking process accuracy. In-situ measurement and process control can offer an effective solution. In AM based on metals, the temperature field of melting pool has critical impacts on phase transformation and mechanical properties. Researchers have developed various approaches to track real-time temperature during ultrahigh temperature in AM. Nevertheless, large temperature gradient around the energy source demands a capable measurement system and method due to the limitations of the conventional infrared cameras and pyrometers. This study will explore the deficiency and improvement of the existing approaches with a focus on the cutting-edge methods of AM process temperature measurement, along with a critical thinking about the follow-up usage of the collected data. Specifically, it will report the status and trends in employing various machine learning and advanced control techniques with the in-situ sensor data for process qualification purposes.

null

Rosen, David W.

2019-12-05T16:56:51Z

2004

Mechanical Engineering

null

['https://hdl.handle.net/2152/78646', 'http://dx.doi.org/10.26153/tsw/5702']

eng

2004 International Solid Freeform Fabrication Symposium

Open

WTEC Additive/Subtractive

Overview of the WTEC Additive/Subtractive Manufacturing Study of European Research

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1848110b-0f6d-4425-9193-f12cecc633a4/download

null

As a follow-up to the 1996 JTEC/WTEC study of rapid prototyping research in Europe and Japan, the 2003 Additive/Subtractive Manufacturing study assessed the evolution of RP technologies and new developments in the area. The goal of this study was to gather information on the worldwide status and trends in additive/subtractive (A/S) manufacturing science and technology and disseminate it to government decision makers and the research community. This talk will present the primary observations, results, and conclusions of the study. Highlights include: The European Union has an organized effort to make advances in A/S manufacturing, the levels of activity and infrastructure are superior to the US, and European countries have targeted rapid manufacturing - the science and technology of production manufacture using A/S technologies. The talk also provides the context for subsequent presentations in the Session on European SFF Programs.

null

['Ma, Changyu', 'Lin, Yu-Keng', 'Zheng, Tianqi', 'Mallory, Phillip', 'Zhu, Jianhao', 'Morris Wang, Y.', 'Li, Xiaochun', 'Kang, Bruce', 'Li, Bingbing']

2024-03-26T16:44:48Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124367', 'https://doi.org/10.26153/tsw/50975']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['ODS SS316L', 'Y2O3', 'additive manufacturing', 'grain refinement']

Oxide Dispersion Strengthened (ODS) SS316L Prepared by Laser Powder Bed Fusion (L-PBF): Analysis of Microstructure and Hardness Properties

Conference paper

https://repositories.lib.utexas.edu//bitstreams/121ab036-66e0-4bd9-a6a8-37bba7dfbfd2/download

University of Texas at Austin

In this paper, dense oxide dispersion-strengthened (ODS) SS316L with 0.5 wt.% Y2O3 was fabricated using nano-Y2O3-embedded spherical SS316L powder via laser powder bed fusion (LPBF). The molten pool, oxide dispersion, cellular structure, and microhardness of the as-printed ODS SS316L were investigated through optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-Ray Spectroscopy (EDX), and Vickers hardness testing, respectively. The results reveal a uniform dispersion of Y-rich nanoparticles in as-printed ODS SS316L, contributing to the development of a fine-grain structure in the as-printed ODS SS316L. A wide and shallow molten pool was observed in as-printed ODS SS316L, and enhanced microhardness was observed in ODS SS316L compared to pristine SS316L. The effects of Y2O3 on microstructure evolution and reinforcing mechanisms of microhardness are discussed.

null

['Wang, Xiangpang', 'Haiou, Zhang', 'Guilan, Wang']

2021-10-11T22:28:32Z

8/16/13

Mechanical Engineering

null

['https://hdl.handle.net/2152/88669', 'http://dx.doi.org/10.26153/tsw/15603']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['complicated cavity part', 'discrete Voronoi diagram', 'distance map', 'path planning', 'additive manufacturing']

Parallel Contour Path Planning for Complicated Cavity Part Fabrication using Voronoi-based Distance Map

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9691d893-782a-4260-8b64-c7591ed7f7cd/download

University of Texas at Austin

To generate parallel contour path for direct production of complicated cavity component, a novel path planning based on Voronoi-based distance map is presented in this paper. Firstly, the grid representation of polygonal slice is produced by hierarchical rasterization using graphics hardware acceleration and divided into Voronoi cells of contour by an exact EDT (Euclidean distance transformation). Then, each VCI (Voronoi cell of inner contour) is further subdivided into CLRI (closed loop region of inner contour) and OLRI (open loop region of inner contour). Closed paths for each CLRI and the block merging VCO (Voronoi cell of outer contour) and all OLRIs are generated by local and global isoline extraction, respectively. The final path ordered in circumferential and radial directions is obtained by sorting and connecting all individual paths. In comparison with conventional methods such as pair-wise intersection and Voronoi diagram, the proposed algorithm is numerically robust, can avoid null path and self-intersection because of the application of distance map and discrete Voronoi diagram. It is especially used for FGM (Functionally Graded Material) design and fabrication.

null

['Kirschman, C.F.', 'Jara-Almonte, C.C.']

2018-04-18T17:41:00Z

1992

Mechanical Engineering

doi:10.15781/T2NS0MF5K

http://hdl.handle.net/2152/64365

eng

1992 International Solid Freeform Fabrication Symposium

Open

['Mechanical Engineering Department', 'Center for Advanced Manufacturing', 'CAD system']

A Parallel Slicing Algorithm for Solid Freeform Fabrication Processes

Conference paper

https://repositories.lib.utexas.edu//bitstreams/444fb9f6-cf03-4c32-bba3-bf77599fe7f7/download

null

Slicing can accountfor more than 60% ofthe time to prepare apartforbuildingon astereolithographic apparatus. To improve the preparation time, aparallel slicing algorithm was developed. The algorithm was run on aButterfly GP1000 using 2,4,8, 16, and 32processors and superlinear speedup was observed due to high memory requirements. The parallel algorithm can reduce slice times by up to 92% on 16 concurrentprocessors as compared to a single processor.

null

['Kumar, Kannan Suresh', 'Sparks, Todd E.', 'Liou, Frank']

2021-10-21T17:04:00Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89407

eng

2015 International Solid Freeform Fabrication Symposium

Open

['laser metal deposition', 'wire feed', 'wire feed additive manufacturing', 'process parameters']

Parameter Determination and Experimental Validation of a Wire Feed Additive Manufacturing Model

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c6f65c6f-aeef-4a16-ba68-368e888be11e/download

University of Texas at Austin

Laser metal deposition with wire feed is one of the additive manufacturing methods with great scope and robustness. Process parameters plays an important role in controlling the process and obtaining an ideal manufactured part. Simulations tools are highly essential in determining the ideal parameters and melt pool conditions. The current work is a transient 3D model of wire feed additive manufacturing which realizes the heat transfer and fluid flow behavior of the process with varying laser power and power density. The model was programmed in Python and a 1 KW Gaussian beam fiber laser was used to conduct experiments. The effect of laser exposure to the scanned and deposited profile on Ti-6Al-4V alloy is obtained. The comparison of simulation and experimental results shows that this model can successfully predict the temperature profile, and solidified metal profile. The optimum input parameters based on material properties can be identified using the model.

null

['Zhao, Xiayun', 'Rosen, David W.']

2021-10-21T18:21:04Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89418

eng

2015 International Solid Freeform Fabrication Symposium

Open

['Exposure Controlled Projection Lithography', 'interferometric curing monitoring', 'sensor model', 'calibration model']

Parameter Estimation Based Real-Time Metrology for Exposure Controlled Projection Lithography

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e5f2bcf1-9d33-4c88-b7a9-79b1b25a021d/download

University of Texas at Austin

Exposure Controlled Projection Lithography (ECPL) is a layerless mask-projection stereolithography process, in which parts are fabricated from photopolymers on a stationary transparent substrate. To enable advanced closed-loop control for ECPL, an in-situ interferometric curing monitoring (ICM) system has been developed to infer the output of cured height. However, the existing ICM method based on an implicit model and rough phase counting is not fast and accurate enough. This paper reports on a new ICM method to address the modeling and algorithms issues confronted by the current ICM method. The new ICM model includes two sub-models: a sensor model of instantaneous frequency based on interference optics and a calibration model. To solve the models, a moving horizon exponentially weighted online parameter estimation algorithm and numerical integration are adopted. As a preliminary validation, offline analysis of interferograms acquired in an ECPL curing experiment is presented. The agreement between ICM estimated cured height and ex-situ microscope measurement indicates that the overall scheme of the new ICM measurement method with a well-established model, evolutionary estimation and incremental accumulation, is promising as a real-time metrology system for ECPL. The new ICM method is also shown to be able to measure multiple voxel heights consistently and simultaneously, which is desired in global measurement and control of ECPL.

null

['Zhu, Wei', 'Yan, Chunze', 'Yang, Jiayi', 'Wen, Shifeng', 'Shi, Yusheng']

2021-10-21T14:50:35Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89384

eng

2015 International Solid Freeform Fabrication Symposium

Open

['carbon fiber', 'epoxy resin', 'selective laser sintering', 'processing parameters', 'thermoplastics']

Parameter Optimization for Preparing Carbon Fiber/Epoxy Composites by Selective Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/37106114-f8dc-4414-bcaf-66ad7d22f5c6/download

University of Texas at Austin

Carbon fiber (CF) reinforced thermosetting resin composites offer a wide range of high performance features including excellent strength, modulus and thermal resistance and light weight. Consequently, they are increasingly demanded by aerospace and automotive industries due to the tighter requirements of the transport vehicles for lightweight as well as higher payloads. Although thermoplastics and their composites have been widely used in additive manufacturing (AM), to date it is difficult to manufacture carbon fibers reinforced thermosetting composite parts via AM technologies. Therefore, this study developed a novel method based on selective laser sintering (SLS) to fabricate high-performance carbon fiber/epoxy resin composites. The response surface method was employed to study the processing parameters affecting the quality of final parts, and an optimized processing condition was obtained.

null

['Deng, Xioaming', 'Zong, Guisheng', 'Beaman, Joseph J.']

2018-04-19T16:42:03Z

1992

Mechanical Engineering

doi:10.15781/T2G15TT9P

http://hdl.handle.net/2152/64382

eng

1992 International Solid Freeform Fabrication Symposium

Open

['Center for Materials Science and Engineering', 'Department of Mechanical Engineering', 'SLS']

Parametric Analysis for Selective Laser Sintering of a Sample Polymer System

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b26e605b-13a0-4c84-8ecb-273ea3391661/download

null

['Kyriazis, N.', 'Eine, J.', 'Thakur, A.R.']

2024-03-26T21:33:56Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124420', 'https://doi.org/10.26153/tsw/51028']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'deposition pressure', 'freeform', 'multiaxis']

PARAMETRIC ANALYSIS OF DEPOSITION PRESSURE CONTROLLED MULTI-AXIS FREEFORM FABRICATION

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d222319e-a46c-4d5c-8e93-e5b7c5f8bd35/download

University of Texas at Austin

Additive manufacturing is being explored as one of the most promising in-space manufacturing techniques. The presence of micro-gravity enables the fabrication of support-free sparse structures with ease. Sparse lattice structures (e.g. trusses) are attractive for space applications as they can be tailored for specific load paths. Previous studies have identified a positive correlation between deposition pressure and inter-layer adhesion in 3D printing. However, excessive deposition pressures negatively influence the in-orbit printing accuracy. Therefore, a parametric investigation was conducted to determine the optimal deposition pressure to fabricate mechanically sound trusses in orbit. Support-free arches with varying nodal deposition pressures were 3D printed using a multiaxis robotic manipulator with integrated force sensors. Mechanical testing of these arches concluded that the strength improvement plateaus and registers no significant increase in (joint) strength after a certain deposition pressure, characterized by the properties of the extrude. Integration of a force-feedback facilitates free-form printing of complex, multi-layered, support-free structures in terrestrial environments. In a free-floating space environment, it assists in optimizing the overall printing process.

null

['Martin Sun, Ming-shen', 'Beaman, Joseph J.', 'Barlow, Joel W.']

2018-04-10T19:28:33Z

1990

Mechanical Engineering

doi:10.15781/T2JM23Z8N

http://hdl.handle.net/2152/64251

eng

1990 International Solid Freeform Fabrication Symposium

Open

['SSL', "Frenkel's sintering model", 'manufacturing process']

Parametric Analysis of the Selective Laser Sintering Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/18e532ea-e5f6-4d63-a422-0719d115eaac/download

null

Qualitative and quantitative analyses are required to develop Selective Laser Sintering into a viable Manufacturing process. A simplified mathematical model for sintering incorporating the heat tJ;ansfer equation. and the sintering rate equation, but using temperature independent thermal properties, is presented in this paper. A practical result is the calculation of sintering depthdeftned as the depth of powder where the void fraction is less than 0.1 as a function of control parameters, such as the laser power intensity, the laser scanning velocity, and the initial bedtemperature. We derive the general behavior of laser sintering. A comparison of model predictions with laser sinterlng tests is provided.

null

['Fadel, Georges', 'Ganti, Ravi']

2019-02-20T17:13:54Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73453', 'http://dx.doi.org/10.26153/tsw/605']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['Controller', 'galvanometers']

Parametric Based Controller for Rapid Prototyping Applications

Conference paper

https://repositories.lib.utexas.edu//bitstreams/519fe92e-9e9d-45bd-921f-3092450ec0b3/download

null

A methodology aiming at reproducing in Rapid Prototyping applications, exact parametric curves from CAD data is presented. The approach consists of converting the space-based parametric curves from the CAD system into time-base, such that the equations of the curve in terms of time are then fed to a controller directly. Optimization is used to solve the problem, which has both Rapid Prototyping process and scanning constraints. With information such as the equation of the curve, its first and second derivatives with respect to time, a real-time trajectory controller can be designed. The trajectory displays an increase in accuracy over traditional approaches using STL files, which is ofthe order of the chordal tolerance used to generate tessellations. The system model involves electrical and mechanical dynamics of the galvanometers and sensors. The controller, which acts on two mirrors, deflecting the laser beam of a stereolithography machine in the x and y directions respectively, should be easily substituted for current systems. Application of the methodology to freeform curves shows acceptable tracking and can be improved by judicious selection ofthe equation representing the spatial parameter as a function of time.

null

['Chen, Kenwei', 'Crawford, Richard H.', 'Beaman, Joseph J.']

2018-11-16T16:27:27Z

1996

Mechanical Engineering

doi:10.15781/T25D8P10H

http://hdl.handle.net/2152/70295

eng

1996 International Solid Freeform Fabrication Symposium

Open

['SFF', 'tracking control algorithm', 'SLC']

Parametric Representation of Part Contours in SLS Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6cf4b306-1a7d-4e40-bf2e-f3075ecdb121/download

null

Current layer-based SFF technologies process faceted geometric input data to produce polygonal contours of the part's boundary in each layer. However, for improved part quality, other more accurate representations of part contours are desirable. Likewise, implementation of Wu's minimum time optimal laser tracking control method for selective laser sintering (SLS) requires contour curves that exhibit higher order continuity. In this paper, we first analyze the requirements of optimal laser tracking to develop evaluation criteria for choosing a contour representation. Several possible representation methods are reviewed. We show that the NonUniform Rational B-Spline (NURBS) curve meets the criteria. A demonstration program illustrates the advantages of NURBS curves for representing contours with uniform point distributions. The results can be used in other control areas where uniform point distribution or constant velocity is required.

null

['Zhang, Yizhuo', 'Chou, Y. Kevin']

2020-03-02T14:39:55Z

9/14/06

Mechanical Engineering

null

['https://hdl.handle.net/2152/80128', 'http://dx.doi.org/10.26153/tsw/7149']

eng

2006 International Solid Freeform Fabrication Symposium

Open

fused deposition modeling

A Parametric Study of Part Distortions in FDM Using 3D FEA

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7f0b328d-4e09-405d-beba-604c1424b486/download

null

We developed a finite element model to simulate the fused deposition modeling (FDM) process. The model considers the coupled thermal and mechanical analysis and incorporates the element activation function to mimic the additive nature of FDM. Due to repetitive heating and cooling in the FDM process, residual stresses accumulate inside the part during the deposition. The model is also used to evaluate the part distortions, revealing distortion features such as vaulting shapes and distortion-core shifting. A parametric study, three factors and three levels, was performed to evaluate the effects of the deposition parameters on residual stresses and part distortions. Prototype models with larger sizes were fabricated, measured, and compared with the simulations. The simulation results show that (1) the scan speed is the most significant factor to part distortions, followed by the layer thickness, (2) the road width alone is insignificant, however, the interaction between the road width and the layer thickness is significant too, and (3) there are other two-way and three-way interactions that are of secondary significance. Residual stresses increase with the layer thickness, and increase with the road width, to a less extent though, yet largely affected by the layer thickness. The FDM part distortions from the experiment show a similar trend as in the simulations, but no quantitative correlation.

null

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

2021-11-02T15:19:57Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89827

eng

2017 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', 'stainless steel 316L', 'deposition track morphology', 'grain structure']

A Parametric Study on Grain Structure in Selective Laser Melting Process for Stainless Steel 316L

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b54ac663-cb33-4715-af7b-4374910b3691/download

University of Texas at Austin

Laser Selective Melting (SLM) process is used in this work to produce 3-dimensional samples of Stainless Steel (SS) 316L. The effects of laser power, scanning speed, and laser scanning strategy on the track morphology and grain structure are investigated. As the laser heat input is increased by increasing laser power and/or decreasing laser scanning speed, the surface morphology of the SLM track will vary according to the extent of powder melting, and the grain size will increase correspondingly. Different laser scanning strategies can produce different grain patterns, and a noticeable porosity can be found if the scanning strategy is not appropriate. The grains in the bottom layers of the built samples inherit the crystallographic orientations from the substrate through epitaxial growth; nucleation takes places in the top layers and introduces new grains of random crystallographic orientations into the built samples.

null

['Pridham, M.S.', 'Thomson, G.']

2018-05-03T17:05:54Z

1993

Mechanical Engineering

doi:10.15781/T2N29PQ55

http://hdl.handle.net/2152/65040

eng

1993 International Solid Freeform Fabrication Symposium

Open

['Department of Applied Physics and Electronic and Manufacturing Engineering', '3-D welding', 'rapid prototyping', 'BRITE']

Part Fabrication Using Laser Machining and Welding

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f2f2b584-cf7c-4c19-851d-c1b3c532095a/download

null

This paper describes the current work on a laser cutting and welding system for the fabrication of prototype parts in mild and .. stainless steels. The relationship to other rapid prototyping systems and to laminated tool production techniques is discussed, the progress to date is described. Difficulties with current welding procedures are outlined and alternative joining techniques are considered.

null

['Yardimci, M. Atif', 'Guceri, Selcuk I.', 'Agarwala, Mukesh', 'Danforth, Stephen C.']

2018-11-16T15:21:38Z

1996

Mechanical Engineering

doi:10.15781/T26D5PX1T

http://hdl.handle.net/2152/70287

eng

1996 International Solid Freeform Fabrication Symposium

Open

['Fused Deposition', 'thermoplastic materials', 'process analysis']

Part Quality Prediction Tools for Fused Deposition Processing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5228d33e-69e8-4fdd-bc91-4d0a2f085526/download

null

Fused Deposition process fabricates requested part geometries by sequentially depositing discrete curvilinear beads ofmaterial next to and on top of each other. The part integrity depends strongly on the bonding quality at the bead interfaces. Since diffusion bonding of thermoplastic components in the material system is thermally driven, temperature history ofinterfaces determine the bonding quality. Detailed thermal analysis of deposition region and layer building simulation for a model geometry have been performed to investigate local and global material behavior during processing. A simple transport property prediction model has also been developed for the determination of thermal transport properties of the particle loaded systems used in Fused Deposition. Based on the information obtained from thermal models, a computationally efficient part building model has been developed to predict bonding quality in the whole part. The model is driven by the same command file, sml file, that drives the Fused Deposition hardware; and hence is capable of replicating the building process. The model has been tested for a model geometry, spur gear, and three dimensional bonding quality distribution has been predicted for the part.

null

['Zhang, Xinchang', 'Liou, Frank']

2021-11-16T16:29:21Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90336', 'http://dx.doi.org/10.26153/tsw/17257']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['remanufacturing', 'hybrid processing', 'direct laser deposition', 'component repair']

Part Remanufacturing Using Hybrid Manufacturing Processes

Conference paper

https://repositories.lib.utexas.edu//bitstreams/15782a05-d435-4112-835b-a219ce208600/download

University of Texas at Austin

Many users of high-performance metal parts, such as the aerospace industry, the mold/die casting industry, and heavy machinery consumers, extend the service of these damaged parts by employing remanufacturing technology. Additive manufacturing has unique capabilities, such as low heat input, a small heat-affected zone, free-form fabrication, and a near-net-shape. This paper summarizes the effort and the tested results to achieve an automated remanufacturing process using hybrid additive manufacturing and CNC machining processes. It will enable the robust remanufacturing-on-demand to significantly increase operational availability to reduce sustainment costs, thus will lead to robust and quality remanufacturing that is critical for remanufacturing process qualification.

null