ccm/sff-papers · Datasets at Hugging Face

['Mumtaz, K.', 'Vora, P.', 'Hopkinson, N.']

2021-10-04T20:23:25Z

8/17/11

Mechanical Engineering

null

['https://hdl.handle.net/2152/88338', 'http://dx.doi.org/10.26153/tsw/15277']

eng

2011 International Solid Freeform Fabrication Symposium

Open

['metal powder bed', 'additive manufacturing', 'anchors', 'supports', 'overhanging features', 'laser processing', 'powder bed']

A Method to Eliminate Anchors/Supports from Directly Laser Melted Metal Powder Bed Processes

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a0c3d29a-74ea-4e89-9a75-be8ed505bf3c/download

University of Texas at Austin

Metal powder bed AM processes have a significant drawback in that they require anchors/supports to hold overhanging features down during laser processing. This severely restricts the geometries that the processes can make, adds significant time and cost to production and reduces throughput as parts cannot be easily stacked in the build bed. A method to eliminate the need for these anchors/supports has been invented and will be described. Early parts made without anchors will be shown and next steps for research will be discussed.

null

['Guduri, Sashidhar', 'Crawford, Richard H.']

2018-04-19T16:35:34Z

1992

Mechanical Engineering

doi:10.15781/T2KS6JN34

http://hdl.handle.net/2152/64381

eng

1992 International Solid Freeform Fabrication Symposium

Open

['Department of Mechanical Engineering', 'Constructive Solid Geometry', 'CSG']

A Method to Generate Exact Contour Files for Solid Freeform Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b2e5f03d-cf12-4d19-8586-739e32005609/download

null

Existing methods to create contour files generate a polygonal approximation of the contours instead of an exact representation. This paper presents a method to generate exact contours from Constructive Solid Geometry (CSG) representations. The method preserves the accuracy of the contour files provided the primitives used to generate the CSG tree are polygonal or quadric objects. Due to the inclusion of quadric objects into the primitive set an additional effort to solve for the intersection points between two quadric curves is required. The paper also presents a method to convert piecewise quadratic contours to toggle point files for raster scanning solid freeform fabrication processes.

null

['Ott, M.', 'Meihofener, N.', 'Mozgova, I.']

2024-03-26T17:12:28Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124380', 'https://doi.org/10.26153/tsw/50988']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['neural network', 'design time', 'design', 'additive manufacturing']

Methodical Approach to Reducing Design Time by using Neural Networks in Early Stages of Concept Development

Conference paper

https://repositories.lib.utexas.edu//bitstreams/bde10f58-b6b3-4c3a-8038-cd07c762c6bb/download

University of Texas at Austin

Modern companies often face various challenges in concept development of products or systems. Design engineers prepare initial concepts as 3D models. These are then simulated by computational engineers. If requirements are not met, this necessitates an iterative process that runs between the design and computation departments until a valid concept is created. Design methods such as topology optimization are often used here. The upcoming result is then attempted to be adapted to certain manufacturing processes. These iteration loops can sometimes take a very long time, since the model construction and structural optimization generate large computational efforts. The present work shows on an example a methodical approach, which represents a first proof of concept, to solving this problem, including a description of methods and techniques, as well as possible problems in a detailed analysis concerning training data for neural networks and their abstraction capabilities. It is evident that additional research work needs to be conducted for further utilization in order to address all arising questions.

null

['Borstell, D.', 'Walker, N.', 'Kurz, S.']

2021-11-30T20:51:53Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90543', 'http://dx.doi.org/10.26153/tsw/17462']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['orthosis', 'left hand', 'double bass', 'perception', 'methodology', '3D printing']

Methodical Design of a 3D-Printable Orthosis for the Left Hand to Support Double Bass Perceptional Training

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1ca0a87c-14b3-4765-a94c-4274ae8e29f2/download

University of Texas at Austin

The evolution of Additive Manufacturing (AM) in the past decades has opened up its use to a wide range of new applications where conventional manufacturing methods dominated. Orthoses are medical devices, mostly used on legs or arms after injuries or surgery. Amongst other functions, they limit the possible movement of limbs or joints to prevent excessive movements or loads during remobilization. Their manufacturing process is predominantly manual and conventional using e.g. plaster casts and materials like foam, wood and textiles. Playing the acoustic double bass requires precise positioning of the left hand fingers on the fingerboard. Perception of the finger spacing is very important for good intonation. Different educational approaches have therefore been made to kinesthetic and perceptional training. Miniaturization and low forces allow applying additive manufacturing technology to a previously conventional device leading to a new approach to design a perceptional training device for the left hand: an individually shaped orthosis, which is lightweight, low cost, and adjustable and which can be worn during instrument practice.

null

['Uí Mhurchadha, S.M.', 'Huynh, M.P.', 'Quinn, P.T.', 'Tomaz, I.', 'Raghavendra, R.']

2021-12-01T22:01:47Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90630', 'http://dx.doi.org/10.26153/tsw/17549']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['smart components', 'experimental characterisation', '316L stainless steel', 'smart component']

A Methodology for the Embedding of Sensors in Components Manufactured Using Metal Laser Powder Bed Fusion

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1df0ad21-48a8-4df5-8019-326925f53fbc/download

University of Texas at Austin

This paper presents a methodology for the embedding of a sensor in a 316L stainless steel component during the laser powder bed fusion process. The aim of this study is to overcome the drawbacks of traditional sensor attachment to the surface of a component via placing sensors into a part during the manufacturing process. A methodology for the embedding process that ensures the functionality of the sensor within the component is presented and a preliminary investigation into the effect of the embedding process on the manufactured part quality preformed. An off-the-self accelerometer was embedded into a turbine and tested under rotational loading conditions. The interface microstructure where the print was stopped is also studied to investigate the effect of the sensor embedding methodology on material properties. The embedded sensor is capable of detecting off-axis rotation and over-speed of the turbine, two critical loading conditions that cause failure in turbines.

null

['Tyvaert, Irenee', 'Fadel, Georges', 'Rouhaud, Emannuelle']

2019-03-08T17:40:53Z

1999

Mechanical Engineering

null

['https://hdl.handle.net/2152/73571', 'http://dx.doi.org/10.26153/tsw/713']

eng

1999 International Solid Freeform Fabrication Symposium

Open

['Reverse Engineering', 'Rapid Prototyping']

A Methodology to Create STL Files from Data Point Clouds Generated with a Coordinate Measuring Machine

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0e63b2b9-7796-47eb-bc53-34f535ed8451/download

null

Industries have always had the need to reproduce objects especially when drawings are no longer or were never available (reverse engineering). Coordinate measurement machines, whether touch- or laser-based, enable users to generate a point cloud representing a surface. The aim of this work is to develop a methodology and its translation into a software program to generate closed STL file models from such data point clouds. The first step in the research is to develop an algorithm to merge several surfaces (data point clouds) from a real object in exactly the same reference frame. Then, a tessellation program is implemented to creat~ the STL file considering computational costs and minimizing the number oftriangles while maintaining the accuracy ofthe original part. The implementation is illustrated on two examples and conclusions are drawn.

null

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

2021-10-11T21:15:30Z

2013

Mechanical Engineering

null

['https://hdl.handle.net/2152/88644', 'http://dx.doi.org/10.26153/tsw/15578']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['Cholesky algorithm', 'stiffness matrix', 'additive manufacturing', 'thermo-mechanical properties prediction', 'finite element analysis']

Methods for Enhancing the Speed of Numerical Calculations for the Prediction of the Mechanical Behavior of Parts Made Using Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b3a9e96f-f46d-4563-8e69-faa54f43fc6d/download

University of Texas at Austin

Finite element modeling (FEM) is one of the most common methods for predicting the thermo-mechanical properties of 3D structures. Since FEM was developed primarily to analyze and optimize structures that would then be mass-produced, the time for modeling was small compared to the time required to produce the components. With the advent of Additive Manufacturing (AM) it is now possible to produce and test complex parts more quickly than FEM methods can predict their mechanical performance. As such, an enhanced numerical method for quickly solving for the mechanical behavior of components is needed to fully take advantage of the speed and versatility of this new manufacturing paradigm. In order to enhance the computational efficiency of FEM, a novel method was developed to adapt FEM for prediction of fundamental deformation responses of AM-produced parts. A general FEM strategy comprised of constructing the stiffness and external stimuli (such as laser power or pressure) as matrices and vectors respectively has been formulated. Thermo-mechanical response is calculated by obtaining the compliance matrix from the stiffness matrix and then multiplying the corresponding values of the compliance matrix with the external stimulus vector. Obtaining the compliance matrix from the stiffness matrix is accomplished, in most cases, using a well-known Cholesky algorithm which starts by transforming the stiffness matrix into a lower triangular matrix with zeros above its diagonal [1]. In this study, the Cholesky algorithm has been improved by identification of discrete sparse bands and by eliminating many zero multiplications in the lower triangular matrix to obtain the thermo-mechanical response much faster than currently available algorithms. In addition, the vector based storage strategy of the above-mentioned discrete sparse bands and multipliers have been used to save computer storage space, including free cache memory, resulting in faster computations. An example showing the time advantage of this new framework over previously used algorithms to obtain the deformation response of an additively manufactured axial beam is provided along with its theoretical background.

null

['Turk, Tunay', 'Hung, Chia-Hung', 'Hossein Sehhat, M.', 'Leu, Ming C.']

2021-12-06T23:21:04Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90714', 'http://dx.doi.org/10.26153/tsw/17633']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['automation', 'laser foil printing', 'laser based metal additive manufacturing']

Methods of Automating the Laser-Foil-Printing Additive Manufacturing Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/63872eea-9d98-4b53-9149-1e48fb746a68/download

University of Texas at Austin

Laser Foil Printing (LFP) is a laser-based metal Additive Manufacturing (AM) method recently developed at Missouri University of Science and Technology. This study investigates and compares two different methods of automating part fabrication for the LFP process. Specifically, the edge elevation issue due to laser cutting is investigated. Edge elevation occurs after the foil cutting operation, which is an essential step of the LFP process. Previously, mechanical polishing was done to remove the elevated edges for the fabrication of each layer. However, as mechanical polishing is very time-consuming, the current study focuses on two other methods to eliminate the elevated edges. One of them uses laser polishing to remove the elevated edges. Another method is changing the order of the fabrication steps between pattern welding and contour cutting in the LFP process. Comparisons are made to observe the differences in part quality, properties, and building time between these two methods.

null

['Beller, Z.J.', 'Secor, E.B.', 'Lavin, J.', 'Keicher, D.M.', 'Essien, M.', 'Whetten, S.', 'Mani, S.S.']

2021-11-10T21:33:16Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90182', 'http://dx.doi.org/10.26153/tsw/17103']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['anti-reflective coatings', 'optics', 'deposition', 'deposition methods', 'additive manufacturing']

Methods of Depositing Anti-Reflective Coatings for Additively Manufactured Optics

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5ea7613d-96ae-4708-b796-89c10f02b8cb/download

University of Texas at Austin

Recent advancements in the field of additive manufacturing (AM) have enabled the production of high-fidelity optical components allowing for the design of novel fiber optic systems. In order to support this emerging technology, methods of depositing anti-reflective coatings (ARCs) onto these optical components must be developed. Work has begun to identify such coating materials; develop systems capable of accurately depositing controlled, uniform layers onto given substrates; establish deposition procedures for ensuring coating validity; and establish post-processing procedures to ensure the reliability of finished components. Areas of interest for finished components include their integration into high-bandwidth fiber optic systems, enabling further miniaturization of communication components. Methods of ARC deposition will be discussed along with final component performance and the identification of key process parameters affecting product performance.

null

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

2021-10-19T20:21:00Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89331

eng

2015 International Solid Freeform Fabrication Symposium

Open

['extrusion-on-demand', 'high solids', 'loading ceramic pastes', 'ceramics paste', 'ram extruder', 'needle valve', 'auger valve']

Methods of Extrusion on Demand for High Solids Loading Ceramic Paste in Freeform Extrusion Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/34c67d5f-9812-42c0-9852-b10b20c8bc85/download

University of Texas at Austin

Fabrication of highly dense parts with complex geometry by paste-extrusion-based solid freeform fabrication processes requires a precise control of the extrusion flow rate to dispense material on demand, which is often referred as Extrusion-On-Demand (EOD). The extrusion process for aqueous ceramic pastes is complex and difficult to control due to their non-Newtonian behavior, compressibility and inhomogeneity. In this study, three methods of EOD (based on ram extruder, needle valve, and auger valve) are introduced and investigated for the extrusion of high solids loading (i.e., >50%, volumetric) aqueous alumina paste. Optimal extrusion process parameters for these methods are determined through printing tests and analysis. The extrusion performance in terms of extrusion start and stop accuracy, as well as flow rate consistency, is compared and analyzed for the three methods. Advantages and disadvantages of these three methods are also discussed.

null

['Hiller, Jonathan', 'Lipson, Hod']

2020-03-09T14:37:05Z

2007

Mechanical Engineering

null

['https://hdl.handle.net/2152/80186', 'http://dx.doi.org/10.26153/tsw/7205']

eng

2007 International Solid Freeform Fabrication Symposium

Open

Digital Freeform Fabrication

Methods of Parallel Voxel Manipulation for 3D Digital Printing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/19642b97-a6ed-4c86-bd2e-581793b828c8/download

null

A novel digital printing concept is explored for desktop fabrication of multimaterial objects with arbitrary 3D geometry. Digital objects are composed of many discrete, self-aligning voxels instead of continuous (analog) deposition techniques. Overall accuracy is determined by the individual voxels instead of the printer, and digital properties such as perfect replication and error correction are physically meaningful. The key challenge in digital printing is massively parallel, deterministic voxel manipulation. To quickly print millions of voxels while keeping errors low, we propose a parallel manufacturing process that exploits electrostatic forces to place an entire 2D pattern of voxels concurrently. Using a custom charged print head, we demonstrate selective 1.5mm voxel pick-up within a larger, self-aligned layer. We expect the principle to scale to million voxel layers using currently available technology.

null

['Fischer, J.', 'Kniepkamp, M.', 'Abele, E.']

2021-10-12T19:56:56Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88727', 'http://dx.doi.org/10.26153/tsw/15661']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['Micro Laser Melting', 'additive manufacturing', 'micro manufacturing', 'micro parts', '316L steel powder']

Micro Laser Melting: Analyses of Current Potentials and Restrictions for the Additive Manufacturing of Micro Structures

Conference paper

https://repositories.lib.utexas.edu//bitstreams/52c78606-f603-4060-8b93-ebaeaa73b649/download

University of Texas at Austin

Although there is a significant requirement for complex micro parts, current metal processing additive manufacturing techniques are limited in achievable part accuracy and geometric resolution. Due to the recently developed process of Micro Laser Melting (MLM) new potentials in micro manufacturing are realizable. This paper gives an overview of the present potentials of MLM using 316L steel powder. While using powder material with a grain size of ≤ 5 µm this technique enables layer thicknesses from 5 to 7 µm. Due to the use of different exposure strategies and laser modes (pulsed and continuous radiation) high aspect ratios up to 260 could be realized with thin wall structures. Furthermore, the influence of laser mode and exposure sequence on the part density, surface quality and accuracy of lattice structures with a minimum wall thickness lower than 40 µm is analyzed.

null

['Cheng, Xudong', 'Schwieso, Patrick', 'Choi, Hongseok', 'Datta, Arindom', 'Li, Xiaochun']

2020-02-13T20:54:10Z

8/30/04

Mechanical Engineering

null

['https://hdl.handle.net/2152/79977', 'http://dx.doi.org/10.26153/tsw/7002']

null

2004 International Solid Freeform Fabrication Symposium

Open

process monitoring

Micro Thin Film Sensor Embedding in Metal Structures for Rapid Production of Miniature Smart Metal Tooling

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4000a7f2-e545-49fa-b208-3c8106b943f3/download

null

In-situ monitoring and control of temperature and strain is important to improve product quality for numerous mesoscale manufacturing processes. However, it is difficult for conventional sensors to provide measurements with a high spatial and temporal resolution at critical locations. This paper studies the fabrication and calibration of micro thin film sensors embedded in metal structures for miniature tooling applications. Micro thin film sensors have been successfully fabricated on various metal substrates and advanced embedding techniques have been developed to ensure sensor function inside metal structures. Specifically, multilayer dielectric/metal thin film micro sensors were embedded into layered metal structures by ultrasonic welding (USW). These embedded sensors provided superior spatial and temporal resolutions. Smart tooling technique will improve safety and reliability significantly for manufacturing processes.

null

['Shuai, Li', 'Wei, Qingsong', 'Shi, Yusheng', 'Zhang, Jie', 'Wei, Li']

2021-10-26T20:14:55Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89574

eng

2016 International Solid Freeform Fabrication Symposium

Open

['micro-crack formation', 'selective laser melting', 'Inconel 625']

Micro-Crack Formation and Controlling of Inconel625 Parts Fabricated by Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2408600f-16a0-4a2f-a705-821469aac4ae/download

University of Texas at Austin

Micro-crack is one of the most serious defects in selective laser melting (SLM), which impair the mechanical properties of the fabricated parts. In this study, Inconel625 superalloy specimens were fabricated by SLM process with progressive alternative scan strategy. The morphology of the cracks, elements distribution were detected by optical microscope (OM), scanning electron microscope (SEM) and electron back scattered diffraction (EBSD). The results showed that a large numbers of micro-cracks occurred at room temperature, with the average length of approximately 100 µm. It was found that crack formation was attribute to the local segregation of Nb and Mo element in the process of rapid solidification, resulting in the generation of low melting temperature eutectic solidification (γ+Laves). Micro-cracks grows along the interface of (γ+Laves) under the thermal stress. Base-plate preheating shows an efficient method to reduce the scales and number of cracks. The residual stress was reduced by more than 50% when preheating at 300℃.

null

['Ware, Henry Oliver T', 'Sun, Cheng']

2021-11-16T15:29:48Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90314', 'http://dx.doi.org/10.26153/tsw/17235']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['microCLIP', 'high-resolution fabrication', 'ceramic resin', 'ceramic resins', 'dimensional accuracy', '3D printing']

microCLIP Ceramic High-Resolution Fabrication and Dimensional Accuracy Requirements

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4bc8ef78-ae46-4dd1-a261-adc2314fa270/download

University of Texas at Austin

Ceramics have been broadly used as structural and functional materials with a wide range of engineering applications. Recent introduction of Continuous Liquid Interface Production (CLIP) uses projection UV photopolymerization and oxygen inhibition to tremendously reduce fabrication time. In addition to 3D printing polymeric materials, it has demonstrated the feasibility of fabricating 3D ceramic parts using photo-curable ceramic resins. However, the associated ceramic particle light-scattering significantly alters the process characteristics of the CLIP process, resulting in broadening of the lateral dimensions in associated with the reduction in the curing depth. Varying the exposure conditions to accommodate the scattering effect further affects the deadzone thickness, which introduces a systematic defocusing error to further complicate the process control. In this work we show that careful characterization and balance of both effects yields an optimal set of process parameters (UV Power and stage speed) for high-resolution 3D fabrication with a given photo-curable ceramic resin.

null

['Vail, N.K.', 'Barlow, J.W.']

2018-04-10T16:20:43Z

1990

Mechanical Engineering

doi:10.15781/T2R78658X

http://hdl.handle.net/2152/64234

eng

1990 International Solid Freeform Fabrication Symposium

Open

['The Center for Materials Science and Engineering', 'Department of Chemical Engineering', 'Selective Layer Sintering', 'SLS']

Microencapsulation of Finely Divided Ceramic Powders

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f21f2bd3-a186-49ef-9040-33b4ad5d2347/download

null

Polymer coated alumina particles have been prepared by spray drying alumina powder with a polymer emulsion. Powders containing a maximum of 50% wt. were obtained. The coated particles were compared to mixtures of alumina and polymer. Oven sintering tests show the coated material to compact more than the mixed and pure polymer materials. Strong, well defined parts with layer thicknesses of 0.002" were produced from both coated and mixed materials by the Selective Layer Sintering process.

null

['Udofia, Edidiong Nseowo', 'Zhou, Wenchao']

2021-11-15T21:45:57Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90280', 'http://dx.doi.org/10.26153/tsw/17201']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['microextrusion', '3D printing', 'evaporation timescale', 'capillary rise', 'standoff distance', 'substrate driven ink flow', 'surface energy', 'PDMS printing']

Microextrusion Based 3D Printing – A Review

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3f122912-7900-4083-9add-268872eed30d/download

University of Texas at Austin

Whilst extrusion-based 3D printing processes have been successfully applied at the macroscale, this seeming simplicity belies the dynamic complexities needed for consistent, repeatable and cost-effective printing at the microscale. To fully tap into the promise of microextrusion (µEP) of fabricating fine resolution features, it is critical to establish an understanding of the fundamentals of ink flow, interface energy, drying, and the process-property relationship of the printing process. Till date, a comprehensive and coherent organization of this knowledge from relevant literature in different fields is still lacking. In this paper, we present a framework of the underlying principles of the microextrusion process, offering an overall roadmap to guide successful printing based on both results in the literature and our own experimental tests. The impacts of various process parameters on the resolution of printed features are identified. Experiments are carried out to validate the developed framework. Key challenges and future directions of microextrusion 3D printing are also highlighted.

null

['Griffith, Michelle', 'Yang, Pin', 'Burns, George', 'Harris, Marc']

2019-11-15T16:05:02Z

2003

Mechanical Engineering

null

['https://hdl.handle.net/2152/78418', 'http://dx.doi.org/10.26153/tsw/5505']

eng

2003 International Solid Freeform Fabrication Symposium

Open

Femtosecond

Microfabrication with Femtosecond Laser Processing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/45cf4965-26eb-4cd5-a759-bc348c972b8d/download

null

Our research investigates the special characteristics of femtosecond laser processing for microfabrication. The ultrashort pulse significantly reduces the thermal diffusion length. As a result, material is removed more efficiently with little damage to the surrounding feature volume. Currently, we are exploring the basic mechanisms that control femtosecond laser processing, to determine the process parameter space for laser processing of metals to address manufacturing requirements for feature definition, precision and reproducibility. One of the unique aspects to femtosecond radiation is the creation of localized structural changes. By scanning the focal point within a transparent material, we can create three-dimensional waveguides. This paper will describe our results to explore femtosecond laser ablation for laser processing of metals and glasses. We will discuss the effect of laser parameters on removal rate, feature size/definition, aspect ratio, material structure, and performance. Examples of component fabrication in metals and glasses will be shown.

This work supported by the U. S. Department of Energy under contract DE-AC04-94AL85000.

null

['Holt, Nicholas', 'VanHorn, Austin', 'Montazeri, Masha', 'Zhou, Wenchao']

2021-11-03T21:58:35Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89945

eng

2017 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'MAPS', 'MEMS', 'microheaters', 'printed electronics', 'powder bed processes']

Microheater Array Powder Sintering: A Novel Additive Manufacturing Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e8ae28f9-3f23-4898-a13f-323ee2cb9ae2/download

University of Texas at Austin

One of the most versatile additive manufacturing (AM) processes is selective laser sintering (SLS), which scans a powder bed with a laser beam to fuse powder particles layer by layer to build 3D objects for prototypes and end products with a wide range of materials. However, it suffers from slow printing speed due to the pointwise scanning and high energy consumption due to the requirement of a high-power laser. In this paper, we propose a novel method of additive manufacturing which replaces the laser beam with an array of microheaters as an energy source to sinter powder particles. This method, referred to as Microheater Array Powder Sintering (MAPS), has the potential to significantly increase the printing speed by layer-wise sintering and reduce the power consumption due to the lower power requirements of the microheater array. This paper is to provide a proof-of-concept for this proposed new method. First, a thin-film microheater is designed and simulated with an experimentally validated numerical model to demonstrate that it can be used as an alternative energy source to sinter powder particles by reaching a target temperature of 600°C within milliseconds at a power consumption of 1.2 Watts. The numerical model is used to simulate the MAPS process by placing the heater in close proximity to the powder particles. Simulation results show that heat can be effectively transferred over an air gap to raise the temperature of the powder particles to their sintering temperature. Different process parameters (e.g., air gap, material properties, time, printing resolution, etc.) are discussed. An experimental MAPS system is then implemented to provide a proof-of-concept with the designed microheater and a custom air gap control apparatus. A straight line is successfully printed on thermal paper using the experimental MAPS system, which suggests the proposed MAPS process is feasible.

null

['Crane, Nathan', 'Nellis, Mike', 'Nolas, George', 'Harmon, Julie']

2020-03-09T13:11:50Z

8/21/07

Mechanical Engineering

null

['https://hdl.handle.net/2152/80170', 'http://dx.doi.org/10.26153/tsw/7189']

eng

2007 International Solid Freeform Fabrication Symposium

Open

solid freeform fabrication

Microscale Freeform Integration by Directed Self Assembly

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b090578e-3e0a-4723-9c65-690e82cffead/download

null

Most solid freeform fabrication (SFF) manufacturing processes assemble uniform components such as powder particles or polymer chains to produce desired geometries. Their capacity for producing highly functional parts (integrated actuation, sensing, and electronics) will dramatically increase when multiple materials and functional subcomponents can be automatically integrated. This paper addresses criteria for a system that integrates multiple materials and components through computer-controlled self-assembly. It builds complex systems from layers of self-assembled micro-components. The paper will address implementation methods, present a concept demonstration, and consider its application to micro-thermoelectric systems. This manufacturing process can be enhanced further through integration with mature additive processes.

null

['Xu, Yi', 'Imamura, Masato', 'Nakagawa, Takeo']

2018-11-29T20:28:05Z

1997

Mechanical Engineering

doi:10.15781/T27S7JC2B

http://hdl.handle.net/2152/70340

eng

1997 International Solid Freeform Fabrication Symposium

Open

['Stereolithography', '3D objects']

Microscopic Flow Observation of Photopolymer by UV-Laser Beam Exposure

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f89cc208-2b06-4a77-86d3-b06c7ea22e2d/download

null

Microscopic flow of liquid photopolylner around the cured polymer was observed during laser exposure. The maximum velocity was about 4 mm/s. The temperature raised by reaction heat, causes the density of liquid photopolymer to vary, resulting in this flow. This flow causes the nearby cured strands to sway and it decreases the accuracy of SL model.

null

['Chartrain, Nicholas A.', 'Vratsanos, Maria', 'Han, Dung T.', 'Sirrine, Justin M.', 'Pekkanen, Allison', 'Long, Timothy E.', 'Whittington, Abby R.', 'Williams, Christopher B.']

2021-10-28T21:59:25Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89711

eng

2016 International Solid Freeform Fabrication Symposium

Open

['tissue scaffold', 'regenerative medicine', 'stereolithography', 'biodegradable', 'polymer']

Microstereolithography of Tissue Scaffolds Using a Biodegradable Photocurable Polyester

Conference paper

https://repositories.lib.utexas.edu//bitstreams/13a2bcaf-6214-4e3a-9ee0-ba4729919841/download

University of Texas at Austin

Due to its ability to create complex cellular geometries with extremely fine resolution, mask projection microstereolithography (MPμSL) can be useful for fabricating designed tissue scaffolds and other biological constructs for use in Tissue Engineering and Regenerative Medicine. However, few photocurable materials with low cytotoxicity, adequate cell adhesion, and degradability can be processed with MPμSL. In this work, we present the fabrication of biocompatible and biodegradable tissue scaffolds with 50 μm feature sizes from a novel polyester using MPμSL. Poly(tri(ethylene glycol)adipate) dimethacrylate (PTEGA-DMA) was synthesized and evaluated for its printability. The curing parameters for printing were identified and scaffolds were fabricated. Optical and electron microscopy were used to determine the achievable feature sizes and accuracy of printed parts using the polymer in the MPμSL system. MC3T3-E1 mouse preosteoblasts were seeded on PTEGA-DMA films to assess adhesion and biocompatibility.

null

['Hanumantha, M.', 'Farhang, B.', 'Ravichander, B.B.', 'Ganesh-Ram, A.', 'Ramachandra, S.', 'Finley, B.E.', 'Swails, N.', 'Amerinatanzi, A.']

2021-12-06T22:41:51Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90702', 'http://dx.doi.org/10.26153/tsw/17621']

eng

2021 International Solid Freeform Fabrication Symposium

Open

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

Microstructural and Mechanical Characterization of Laser Powder Bed Fusion of IN718 Overhangs

Conference paper

https://repositories.lib.utexas.edu//bitstreams/53ceec45-b4b0-461b-b46b-1bfb2b0a511b/download

University of Texas at Austin

Inconel 178 (IN718), a nickel-chromium-based superalloy known for its superior properties is used in aerospace, oil, and gas industries. Due to its high hardness, IN718 is difficult to be machined. Therefore, fabrication of IN718 components with complex geometries is a big challenge when conventional manufacturing techniques are used. Laser powder bed fusion (LPBF) technique can be used to fabricate IN718 parts with high precision. During fabrication of overhang structures, supports are typically employed, which significantly increases the use of resources such as material consumption and postprocessing. The focus of this study is to determine the angle at which an overhang structure can be fabricated without employing supports. To this aim, the angled-overhang samples with varied angles (30°-90°) were manufactured with no support. The effect of overhang state on the microstructural and mechanical properties of the LPBF-processed IN718 samples was analyzed. According to the microstructural analysis, the deepest melt pools in the overhang sample seemed to be at a hanging angle of 45°. Moreover, the overhang sample fabricated at 45° had the greatest Vickers hardness value of 382.90 HV. This study urges a reconsideration of the common approach of selecting supports for overhang samples in the LPBF process when a higher quality of the as-fabricated parts is desired.

null

['Ewing, Cody', 'Wu, Yan', 'Yang, Li']

2021-11-09T20:01:18Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90149', 'http://dx.doi.org/10.26153/tsw/17070']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['Ti6Al4V', 'cellular struts', 'microstructure', 'mechanical characterization', 'electron beam powder bed fusion', 'EB-PBF', 'additive manufacturing']

Microstructural and Mechanical Characterization of Ti6Al4V Cellular Struts Fabricated by Electron Beam Powder Bed Fusion Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/64ea57a6-a79f-46c7-ac6f-a98cb795e7b9/download

University of Texas at Austin

Despite the widespread use of the electron beam powder bed fusion (EB-PBF) additive manufacturing (AM) process in the fabrication of cellular structures, relatively little is known about the microstructural and mechanical properties of the individual cellular struts of different geometries fabricated by the EB-PBF. In this study, experimental investigation was carried out in the attempt to establish preliminary understanding of the material characteristics of the Ti6Al4V cellular struts using EB-PBF under various geometry design conditions (dimension and orientation angle). It was found that there exist significant geometry effects for the material characteristics of the Ti6Al4V cellular struts, which indicates that a non-uniform material model should be considered in the future design of these cellular structures.

null

['Ning, Fuda', 'Hu, Yingbin', 'Liu, Zhichao', 'Wang, Hui', 'Cong, Weilong', 'Li, Yuzhou']

2021-10-27T21:15:57Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89616

eng

2016 International Solid Freeform Fabrication Symposium

Open

['laser engineered net shaping', 'LENS', 'Al2O3 nanoparticle reinforced composites', 'microstructures', 'microhardness', 'compressive properties']

Microstructural and Mechanical Performance of Al2O3 Nanoparticle Reinforced 17-4 PH Stainless Steel Bulk Composite Parts Fabricated by Laser Engineered Net Shaping Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/1465a78a-c1ce-461f-ad14-38ebff18d12a/download

University of Texas at Austin

Alloy 17-4 PH (AISI 630) is a precipitation-hardening martensitic stainless steel that has been extensively employed in the industries of aerospace, marine, and chemical. In this study, bulk parts of both 17-4 PH and Al2O3 reinforced 17-4 PH composites were fabricated on a steel substrate by laser engineered net shaping (LENS) process to investigate the effects of Al2O3 reinforcements on the part performance. The 17-4 PH powders were pre-mixed with Al2O3 nanoparticles by ball milling. The microstructures of both parts were observed using scanning electron microscopy and mechanical properties including microhardness and compressive properties were evaluated by means of a Vickers microhardness tester and a universal tester, respectively. The results indicate that Al2O3 reinforced 17-4 PH composite parts fabricated by LENS process exhibited superior microhardness and compressive properties as compared to pure 17-4 PH parts.

null

['Lakshminarayan, Uday', 'Marcus, H.L.']

2018-04-17T18:16:25Z

1991

Mechanical Engineering

doi:10.15781/T2RN30R1X

http://hdl.handle.net/2152/64340

eng

1991 International Solid Freeform Fabrication Symposium

Open

['Center for Materials Science and Engineering', 'Selective Laser Sintering', 'SLS', 'material systems']

Microstructural and Mechanical Properties of Al2O3/P2O5 AND Al2O3/B2O3 Composties Fabricated by Selective Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/af8d903c-bafc-4f6d-b83b-8797923a8ff2/download

null

The feasibility of processing ceramic powders by Selective Laser Sintering has been reported in an earlier paperl . Material systems we have investigated include alumina based systems with ammonium phosphate or boron oxide as low temperature binders which are the systems discussed in this paper. With bOth systems, a secondary heat treat.rJ1ent is necessary to realize the high temperatute properties of the materials. This paper will focus mainly on the mechanical properties of the composite bodies. In particular, the influence of particle size, powder mix composition, laser parameters and secondary heat treat.rJ1ent on density, strength and dimensional stability of the final product will be discussed.

null

['Doris, A.', 'Trujillo, I.', 'Godinez, D.', 'Arrieta, E.', 'Wicker, R.B.', 'Gradi, P.', 'Katsarelis, C.C.', 'Medina, F.']

2024-03-26T16:36:49Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124362', 'https://doi.org/10.26153/tsw/50970']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['Inconel 718', 'laser powder bed fusion', 'geometric feature build plate', 'multiple machine configurations', 'heat treatment', 'microindentation hardness', 'optical microscopy', 'EBSD image mapping', 'microstructure']

Microstructural and microhardness variations of laser powder bed fusion (L-PBF) additively manufactured Inconel 718 due to machine variability and wall thickness for aerospace applications

Conference paper

https://repositories.lib.utexas.edu//bitstreams/08671889-83a3-4fa1-8021-0a78d6ffdaaf/download

University of Texas at Austin

This paper reports on a study investigating the microstructure and microhardness of thin walls fabricated by Laser Powder Bed Fusion (L-PBF) from sixteen geometric feature build plates. The study evaluated any variance in those properties with the variation in thickness by characterizing the XY and YZ planes of seven thin walls of different thicknesses and the base parts. Electron Backscatter Diffraction (EBSD) analysis with inverse pole figure (IPF) mapping was done for four samples from four different machine manufacturers. From the EBSD grain boundary map, the microstructure is composed of equiaxed grains with a lower threshold angle with smaller grains in the border area. Compositional analysis for both the powders and the resulting fully heat-treated LPBF manufactured material was analyzed for alloy element stability and contaminants using 10 mg samples. The paper concludes by showing the relationship between composition and microstructural properties.

null

['Gong, X.', 'Lydon, J.', 'Cooper, K.', 'Chou, K.']

2021-10-12T22:59:01Z

2014

Mechanical Engineering

null

['https://hdl.handle.net/2152/88765', 'http://dx.doi.org/10.26153/tsw/15699']

eng

2014 International Solid Freeform Fabrication Symposium

Open

['electron beam additive manufacturing', 'additive manufacturing', 'beam scanning speed', 'microstructure', 'Ti-6Al-4V']

Microstructural Characterization and Modeling of Beam Speed Effects on Ti-6Al-4V by Electron Beam Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/d2a06ce7-348d-45c8-a4a1-4e01b5e910a1/download

University of Texas at Austin

In this study, the influence of the beam scanning speed to the microstructure of Ti-6Al4V parts processed by EBAM is investigated. EBAM parts were fabricated with 4 different scanning speeds, ranging from 214 mm/s to 689 mm/s, and the microstructures were studied. In addition, the volume fractions of different phases were obtained by thermal and phase transformation modeling. The microstructure is characterized by columnar structures of prior β grains along the build direction, and fine Widmanstätten (α+β) structure and α′ martensites are presented inside of the prior β. Both the prior β grain size and α-lath thickness decrease with the increase of the scanning speed. For the phase constitution, the volume fraction of α′ increases with the scanning speed while the volume fraction of α decreases due to the increase of cooling rate during solid phase transformation. The results from the analytical phase transformation model are consistent with the microstructure characterization from the experiment.

null

['Fu, Tian', 'Fan, Zhiqiang', 'Pulugurtha, Syamala R.', 'Sparks, Todd E.', 'Ruan, Jianzhong', 'Liou, Frank', 'Newkirk, Joseph W.']

2020-03-10T17:37:47Z

2008

Mechanical Engineering

null

['https://hdl.handle.net/2152/80236', 'http://dx.doi.org/10.26153/tsw/7255']

eng

2008 International Solid Freeform Fabrication Symposium

Open

Laser Direct Metal Deposition

Microstructural Characterization of Diode Laser Deposited Ti-6Al-4V

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e61495da-acd9-4974-9cbf-42ba33c9b98b/download

null

Laser Direct Metal Deposition (DMD) is an effective approach to manufacturing or repairing a range of metal components. The process is a layer-by-layer approach to building up a three dimensional solid object. The microstructure influences mechanical properties of the deposited parts. Thus, it is important to understand the microstructural features of diode laser deposited parts. This paper presents a microstructure analysis of a diode laser deposited Ti-6Al-4V onto a Ti-6Al-4V substrate.

null

['Doris, A.', 'Trujillo, L.', 'Godinez, Dana', 'Arrieta, E.', 'Wicker, R. B.', 'Gradl, P.', 'Medina, F.']

2023-03-30T15:58:19Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117693', 'http://dx.doi.org/10.26153/tsw/44572']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Additive manufacturing', 'laser powder bed fusion (L-PBF)', 'Inconel 718', 'Microstructural Characterization']

Microstructural Characterization of Laser Powder Bed Fusion (L-PBF) Additively Manufactured Inconel 718 for Aerospace Application

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f2f330fd-0995-409f-963c-5090d8540dba/download

null

Alloy 718 (Inconel 718) is used for aerospace applications because of its excellent corrosion resistance and mechanical properties. This alloy is particularly applicable in manufacturing components subjected to high temperatures in rocket engines, aero-engines, and gas turbines. Properties for this alloy when processing on systems from similar and different Laser Powder Bed Fusion (L-PBF) machines provide subtle differences due to process parameters, feedstock, and machine configurations. A series of sixteen L-PBF AM Inconel 718 geometric feature build plates have been evaluated for microstructure using optical microscopy. This study presents the details of the microstructure analysis concerning geometry and different machine platforms. Microstructural investigations of these samples included average grain width measurement for all the X-Y and Y-Z build layers and are accompanied by process parameters and powder characterization. The present work concludes with a discussion on the importance of captured differences among builds to understand the practical limitations among AM platforms.

null

['Basak, Amrita', 'Das, Suman']

2021-10-26T19:36:52Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89567

eng

2016 International Solid Freeform Fabrication Symposium

Open

['MAR-M247', 'scanning laser epitaxy', 'microstructure', 'nickel-based superalloy']

Microstructural Characterization of MAR-M247 Fabricated Through Scanning Laser Epitaxy

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2d3aa7fb-b68e-4daa-bc91-ba0c7ba2e207/download

University of Texas at Austin

Nickel-base superalloys are extensively used to produce gas turbine hot section components as these alloys offer improved creep strength and higher fatigue resistance compared to other alloys due to the presence of precipitate-strengthening phases such as Ni3Ti or Ni3Al (γ' phases) in the normally face-centered cubic (FCC) structure of the solidified nickel. Although this second phase is the main reason for the improvements in properties, presence of such phases also results in increased processing difficulties as these alloys are prone to crack formation. In this work, we demonstrate powder bed fusion-based additive manufacturing of MAR-M247 onto like-chemistry substrates through scanning laser epitaxy (SLE). The SLE deposited MAR-M247 followed the polycrystalline morphology of the underlying MAR-M247 substrate. Metallurgical continuity was achieved across the entire deposit-substrate interface and the samples showed no warpage during the laser processing across a broad range of processing parameters. Optical imaging, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) were carried out to characterize the microstructural refinement in the SLE fabricated MAR-M247.

This work is sponsored by the Office of Naval Research through grants N00014-11-1-0670 and N00014-14-1- 0658.

null

['Cima, M.J.', 'Lauder, A.', 'Khanuja, S.', 'Sachs, E.']

2018-04-19T18:17:45Z

1992

Mechanical Engineering

doi:10.15781/T2W37MC63

http://hdl.handle.net/2152/64402

eng

1992 International Solid Freeform Fabrication Symposium

Open

['Three Dimensional Printing', 'rapid prototyping', '3DP']

Microstructural Elements of Components Derived from 3D Printing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f00d2d88-6b31-4ae6-9392-f16d0bf2b030/download

null

['Niino, Toshiki', 'Haraguchi, Hisashi', 'Itagaki, Yutaro', 'Hara, Kentaro', 'Morita, Susumu']

2021-10-06T20:46:07Z

8/22/12

Mechanical Engineering

null

['https://hdl.handle.net/2152/88440', 'http://dx.doi.org/10.26153/tsw/15377']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['preheat free processed parts', 'microstructural observation', 'laser sintering', 'plastic parts']

Microstructural Observation and Mechanical Property Evaluation of Plastic Parts Obtained by Preheat Free Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7f3d7d83-d0bc-4953-8889-4f7bd6cd5474/download

University of Texas at Austin

Tensile test on preheat free (PF) processed part was performed it is shown that ultimate strength is the same as that from conventional process when relative density is the same. Microstructural observation showed that decomposition occurs during PF process. Microstructure of PF processed part is similar to those of amorphous. It is indicated that preheat free process can improve geometrical precision. PGA to which conventional process cannot be applied was successful processed by PF. Tensile test on preheat free (PF) processed part was performed it is shown that ultimate strength is the same as that from conventional process when relative density is the same. Microstructural observation showed that decomposition occurs during PF process. Microstructure of PF processed part is similar to those of amorphous. It is indicated that preheat free process can improve geometrical precision. PGA to which conventional process cannot be applied was successful processed by PF.

null

['Sterling, Amanda J.', 'Torries, Brian', 'Shamsaei, Nima', 'Thompson, Scott M.', 'Daniewicz, Steven R.']

2021-10-20T21:26:12Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89365

eng

2015 International Solid Freeform Fabrication Symposium

Open

['Laser Engineered Net Shaping', 'fatigue', 'porosity', 'Ti-6Al-4V']

Microstructural Sensitive Fatigue Modeling of Additively Manufactured Ti-6Al-4V

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a7480ab9-aa56-4f83-a789-fe6fb10b85d7/download

University of Texas at Austin

A common issue in powder-based Additive Manufacturing (AM) techniques is porosity. While process parameters can be controlled to limit this occurrence, complete elimination without post-processing is difficult. Because porosity can significantly affect fatigue behavior of AM parts, it is important to understand and model this material trait. In this study, the porosity in various Ti-6Al-4V specimens fabricated via Laser Engineered Net Shaping (LENS) was determined prior to fatigue testing. Void distribution and morphology was quantified. Fractography was performed to determine the specimen’s transition through crack initiation and propagation stages. These results were used to calibrate a microstructure-sensitive fatigue model for predicting the fatigue behavior of as-built and heat treated LENS Ti-6Al-4V.

null

['Zhang, Yuanjie', 'Song, Bo', 'Zhang, Lei', 'Wang, Zhiwei', 'Shi, Yusheng']

2021-11-02T19:38:26Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89877

eng

2017 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', 'amorphous alloys', 'crack']

Microstructure and Crack Distribution of Fe-Based Amorphous Alloys Manufactured by Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6bc670eb-2d5b-47fe-be3e-0986e23b9d86/download

University of Texas at Austin

In this study, Fe-based amorphous alloys with a length and width of 10 mm and height of 6 mm were prepared by selective laser melting (SLM). X-ray diffraction, Differential Thermal Analysis and Scanning Electron Microscope were used to investigated the effect of scan space and strategy on the crystallization, microstructure, crack distribution and density. The content of amorphous calculated by Differential Thermal Analysis is up to 93%. There is an obviously trend to lower crack distribution and higher density with an appropriate scan spaces and strategies. With the increasing scan space, the density increased first, then gradually decreased, while the crack decreased and then increasing with the scan space.

null

['Bauer, T.', 'Spierings, A.B.', 'Wegener, K.']

2021-10-28T22:36:50Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89719

eng

2016 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', 'additive manufacturing', 'anti-magnetic shielding alloy', 'magnetic properties']

Microstructure and Electro-Magnetic Properties of a Nickel-Based Anti-Magnetic Shielding Alloy

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c3acc281-9b8e-44fd-997e-029cc6df6a73/download

University of Texas at Austin

Selective Laser Melting (SLM) is capable producing high performance parts e.g. for the aerospace or turbine industry. Nonetheless there is a high potential in other sectors such as in the electronic industry. For these applications, optimal properties of magnetic flux, coercive force and hysteresis are required. An isotropic microstructure is favoured - a condition hardly achieved by the SLM process. The SLM-processing window for a NiFe14Cu5Mo4 alloy is developed and basic microstructure is presented. The electro-magnetic properties are measured using a specific test bench allowing a direct comparison of the properties with a reference material. The results are discussed with a specific focus on the effect of the microstructure on the industrial usage.

null

['Zhang, Jingwei', 'Zhang, Yunlu', 'Liou, Frank', 'Newkirk, Joseph W.', 'Brown-Taminger, Karen M.', 'Seufzer, Walliam J.']

2021-10-20T21:39:23Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89367

eng

2015 International Solid Freeform Fabrication Symposium

Open

['laser metal deposition', 'microstructures', 'hardness', 'Vickers hardness', 'Ti6Al4V-TiC']

A Microstructure and Hardness Study of Functionally Graded Materials Ti6Al4V/TiC by Laser Metal Deposition

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c79c5ec2-cb8c-473e-9024-be5a34848953/download

University of Texas at Austin

Crack free functionally graded material (FGM) Ti6Al4V-TiC has been fabricated by laser metal deposition (LMD) using TiC and Ti6Al4V powder which were premixed for different ratios. This study focuses on the influence of laser processing parameters and TiC compositional distribution on microstructure, Vickers hardness and phase. The microstructure is analyzed by scanning electron microscopy (SEM), x-ray diffraction (XRD) and hardness tests. Primary carbide, eutectic carbide and unmelted carbide are found in the deposit area. When laser power increased, the primary and secondary dendrite arm spacing increased. The laser power and scanning speed did not influence the Vickers hardness distribution significantly.

null

['Zhang, M.N.', 'Zhou, X.L.', 'Zhu, W.Z.', 'Li, J.H.']

2021-11-02T19:30:06Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89875

eng

2017 International Solid Freeform Fabrication Symposium

Open

['selective laser melting', 'SLM', 'high-entropy alloy', 'densification', 'microstructure', 'microhardness']

Microstructure and Mechanical Behavior of AlCoCuFeNi High-Entropy Alloy Fabricated by Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3221e562-4504-46b6-9ea6-41595d73dfc4/download

University of Texas at Austin

Additive manufacturing (AM) technique, such as selective laser melting (SLM) is a modern method for materials fabrication and formation. In this study, AlCoCuFeNi HEA parts are fabricated by SLM using prealloyed powders prepared by atomization process. The effect of processing parameters on microstructures, microhardness and compression property of SLM-fabricated HEA parts are systematically investigated. Results show that input laser energy density involved in laser power and scan speed plays a significant role in the densification behavior. A near-full 99.03% density is achieved as an energy density of 102.5 J/mm3 . The alloys consist of simple body-centred cubic (BCC) structure and exhibit the highest microhardness up to 541.17 HV0.2 and compressive strength of 1621.1 MPa due to the BCC solid solution strengthening. The study reveals that SLM is advantageous to produce the high-entropy alloy with high density, good mechanical properties and even complicated shapes.

null

['Bauer, T.', 'Dawson, K.', 'Spierings, A.B.', 'Wegener, K.']

2021-10-20T22:43:57Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89380

eng

2015 International Solid Freeform Fabrication Symposium

Open

['Selective Laser Melting', 'additive manufacturing', 'Haynes® 230®', 'nickel base alloys', 'microstructure', 'mechanical properties']

Microstructure and Mechanical Characterisation of SLM Processed Haynes® 230®

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ccc369c2-3505-4be4-8be4-8e86cdac6b1d/download

University of Texas at Austin

Selective Laser Melting (SLM) enables the production of complex near-net-shaped parts especially out of difficult to machine Nickel based alloys like Haynes® 230®. However, exact knowledge of the SLM processing windows and the corresponding mechanical properties is essential for a target-oriented part design as well as post process planning. Especially the high cooling rate of the small weld pool characterizes the SLM process and is known to cause material microstructures different to standard wrought or cast material. Samples are built with different heat input levels and are analysed for their density, pore- and crack sizes. Optical and scanning electron microscope (SEM) and electron backscatter diffraction (EBSD) are used to characterize the material microstructure. Static tensile test samples were built in either 0° or 90° orientation for the evaluation of mechanical properties at room temperature and anisotropy as well as the influence of the different heat input levels are assessed. It is shown that the alloy itself is well suited for the SLM process allowing the consolidation of nearly defect free material with improved mechanical properties with regards of yield and ultimate tensile strength compared to cast as well as wrought material.

null

['Nastac, Mihaela', 'Klein, Rick Lucas Andrew']

2021-11-02T15:17:18Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89826

eng

2017 International Solid Freeform Fabrication Symposium

Open

['microstructure', 'mechanical property', '316L', 'stainless steel', 'binder jetting', 'electron beam melting', 'selective laser melting']

Microstructure and Mechanical Properties Comparison of 316L Parts Produced by Different Additive Manufacturing Processes

Conference paper

https://repositories.lib.utexas.edu//bitstreams/540dffbb-f348-4382-aada-ec634337e724/download

University of Texas at Austin

316L stainless steel alloy is well known for its corrosion resistance and combination of strength and ductility. By using direct metal additive manufacturing, 316L parts can be produced with volumes and complexity that were previously unachievable. Three of the major metal additive manufacturing technologies – binder jetting, electron beam melting, and selective laser melting – produce SS316L parts, but with different material properties and microstructures. This paper will examine the microstructure and mechanical properties differences between parts produced by the three methods and discuss recent advances to improve microstructure and mechanical performance of metallic alloy parts produced by additive manufacturing.

null

['Ahmad, Nabeel', 'Baig, Shaharyar', 'Ghiaasiaan, Reza', 'Gradl, Paul R.', 'Shao, Shuai', 'Shamsaei, Nima']

2023-01-25T18:27:57Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117294', 'http://dx.doi.org/10.26153/tsw/44175']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Additive manufacturing', 'laser powder bed fusion (L-PBF)', 'laser powder directed energy deposition (LP-DED)', 'Inconel 718', 'grain size', 'tensile properties']

Microstructure and mechanical properties of additively manufactured Inconel 718: A comparative study between L-PBF and LP-DED

Conference paper

https://repositories.lib.utexas.edu//bitstreams/ceea1ffb-21ae-43c3-abca-77c49e90ecab/download

null

This study aims to characterize the microstructure and mechanical properties of Inconel 718 fabricated using two different additive manufacturing processes: laser powder bed fusion (L-PBF) and laser powder directed energy deposition (LP-DED). Similar heat treatments (HTs) including stress-relief (1065ºC for 1.5 hr), hot isostatic pressing (1162ºC under 100 MPa isostatic pressure of Ar gas for 3 hr), solution annealing (1065ºC for 1 hr), and two-step ageing (760ºC for 10 hr + 650ºC for 10 hr) are applied to both batches. Scanning electron microscopy is utilized to characterize microstructural evolution during each step of HTs for both samples. Tensile tests are performed to evaluate the mechanical properties at room temperature. Elongation to failure of L-PBF specimens is measured to be 16% lower than that of the LP-DED ones, while the ultimate tensile and yield strengths of L-PBF specimens are, respectively, 9% and 6% higher, compared to the LP-DED ones. The differences in tensile properties between two specimens are explained using microstructural and fracture surfaces analysis.

null

['Muhammad, Muztahid', 'Gusain, Rukesh', 'Ghiaasiaan, Seyed R.', 'Gradl, Paul R.', 'Shao, Shuai', 'Shamsaei, Nima']

2023-01-25T18:22:33Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117293', 'http://dx.doi.org/10.26153/tsw/44174']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['Additive manufacturing', 'Haynes 230', 'laser powder bed fusion', 'laser powder directed energy deposition', 'tensile properties']

Microstructure and Mechanical Properties of Additively Manufactured Haynes 230: A Comparative Study of L-PBF vs. LP-DED

Conference paper

https://repositories.lib.utexas.edu//bitstreams/99cfdd18-515e-4cc7-a2de-d207f43ff657/download

null

This study investigates the microstructure and room temperature mechanical properties of Haynes 230 fabricated via laser powder bed fusion (L-PBF) and laser powder directed energy deposition (LP-DED). Both L-PBF and LP-DED specimens underwent similar multiple-step heat treatments (HT): stress-relieving (1066°C for 1.5 hours), followed by hot isostatic pressing (at 1163°C and 103 MPa for 3 hours), and solution annealing (1177°C for 3 hours). Microstructural analysis was conducted employing a scanning electron microscope. Uniaxial tensile tests at room temperature were conducted to evaluate the mechanical properties. The change in microstructures after HT and tensile results for both L-PBF and LP-DED specimens were comparable. Upon HTs, the micro-segregation and dendritic microstructure observed in non-heat treated conditions were almost fully dissolved, and carbide phases (M6C/M23C6) formed within grain interiors and grain boundaries in both L-PBF and LP-DED specimens. Finally, the failure mechanisms under tensile load have been studied and compared by fractography.

null

['Ahmad, Nabeel', 'Ghiaasiaan, Reza', 'Gradl, Paul R.', 'Shao, Shuai', 'Shamsaei, Nima']

2024-03-26T16:38:35Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124363', 'https://doi.org/10.26153/tsw/50971']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'laser powder bed fusion', 'laser powder directed energy deposition', 'Haynes 282', 'grain size', 'tensile properties']

Microstructure and Mechanical Properties of Additively Manufactured Haynes 282: A Comparative Analysis between Laser Powder Bed Fusion and Laser Powder Directed Energy Deposition Technologies

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b9684a77-93c3-480b-91be-ee58d82d548d/download

University of Texas at Austin

This study compares the microstructure and tensile properties of Haynes 282 fabricated using laser powder bed fusion and laser powder directed energy deposition. Both sets underwent stress-relieving, followed by hot isostatic pressing, and the standard double aging heat treatment. Tensile testing was conducted at room temperature on specimens fabricated with both technologies to evaluate and compare their tensile behaviors. Results show that the ultimate tensile and yield strengths of laser powder bed fused specimens were 18% and 57% higher, respectively than those of laser powder directed energy deposited ones, whereas the elongation to failure was similar in both. The difference in strengths is attributed to the differences in the size of γ' precipitates and grains, i.e., those in the laser powder directed energy deposited specimens being larger, whereas similar elongation to failure is attributed to the carbide debonding dominating the fracture mechanism in both batches.

null

['Yasa, E.', 'Kempen, K.', 'Kruth, J.-P.']

2021-09-30T15:32:25Z

9/23/10

Mechanical Engineering

null

['https://hdl.handle.net/2152/88264', 'http://dx.doi.org/10.26153/tsw/15205']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['Selective Laser Sintering', 'maraging steel 300', 'heat treatments', 'microstructures', 'mechanical properties']

Microstructure and Mechanical Properties of Maraging Steel 300 After Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/be324be9-85bc-4e41-9ca2-79fad6c89d73/download

University of Texas at Austin

Selective laser melting (SLM) is an additive manufacturing process for the direct fabrication of prototypes, tools and functional parts. The process uses a high intensity laser beam to selectively fuse fine metal powder particles together in a layer-wise manner by scanning cross-sections generated from a three-dimensional CAD model. The SLM process is capable of producing near fully dense functional products without almost any geometrical limitation and having mechanical properties comparable to those produced by conventional manufacturing techniques. There is a wide range of materials that are suitable to be processed by SLM including various steels, Ti, Al and CoCr alloys. Being one of these materials, maraging steel 300 (18Ni-300) is an iron-nickel steel alloy which is often used in applications where high fracture toughness and strength are required or where dimensional changes have to remain at a minimal level, e.g. aircraft and aerospace industries for rocket motor castings and landing gear or tooling applications. To achieve its superior strength and hardness, maraging steel, of which the name is derived from ‘martensite aging’, should be treated with an aging heat treatment. In this study, the effect of the SLM parameters (scan speed and layer thickness) on the obtained density, surface quality and hardness of maraging steel 300 parts is investigated. Moreover, various aging heat treatments (different combinations of duration and maximum temperature) are applied on the SLM parts to achieve high hardness values. The mechanical testing of maraging steel 300 specimens produced by SLM and treated with an appropriate aging treatment is accomplished by impact toughness and tensile tests and compared to the results obtained using conventional production techniques. Additionally, the microstructures of as-built and heat treated parts are investigated.

null

['Feng, Shaw C.', 'Jones, Albert T.', 'Lu, Yan']

2021-12-01T22:50:05Z

2021

Mechanical Engineering

null

['https://hdl.handle.net/2152/90644', 'http://dx.doi.org/10.26153/tsw/17563']

eng

2021 International Solid Freeform Fabrication Symposium

Open

['data alignment', 'data registration', 'microstructure', 'mechanical property', 'additive manufacturing']

Microstructure and Mechanical Test Data Alignment for Additive Manufacturing Data Registration

Conference paper

https://repositories.lib.utexas.edu//bitstreams/548d2741-fd42-444b-808a-315bed1cae43/download

University of Texas at Austin

Melt pool monitoring, microstructure, and mechanical property data are becoming increasingly available and important in additive manufacturing (AM). These data along with data analytics tools can be used to ensure the part’s quality and accelerate the qualification process. A major impediment to correlating these types of data is that they are obtained in different local coordinate systems. To establish the required process-microstructure-property relationships, these data must also be aligned with other build data such as build commands. This paper proposes an innovative data registration procedure to correlate and organize these different types of data.

null

['Zhang, Yunlu', 'Zhang, Jingwei', 'Liou, Frank', 'Newkirk, Joseph']

2021-10-20T21:45:09Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89369

eng

2015 International Solid Freeform Fabrication Symposium

Open

['Ti alloy composites', 'TiB-reinforced composites', 'laser metal deposition']

Microstructure and Property of TiB-Reinforced Ti Alloy Composites by Laser Metal Deposition

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5a3d903a-c392-4768-b69b-10740e1ba825/download

University of Texas at Austin

TiB-reinforced Ti alloy composites have been laser deposited with pre-alloyed Ti-6Al4V-1B powder. The microstructure of the as-deposited and heat treated composites have been characterized in detail using scanning electron microscope (SEM). A homogeneous dispersion of needle-like TiB precipitates is formed in the Ti-6Al-4V α/β matrix. TiB precipitates promote formation of small near equaxed α/β grain after β annealing process. The micro-hardness of the laser deposited composites increase 20-30% with 5 vol. % TiB precipitates compared to unreinforced Ti-6Al-4V deposits.

null

['Brooks, J.', 'Robino, C.', 'Headley, T.', 'Goods, S.', 'Griffith, M.']

2019-03-15T16:22:33Z

1999

Mechanical Engineering

null

['https://hdl.handle.net/2152/73688', 'http://dx.doi.org/10.26153/tsw/830']

eng

1999 International Solid Freeform Fabrication Symposium

Open

['LENS', 'metallurgical']

Microstructure and Property Optimization of LENS Deposited H13 Tool Steel

Conference paper

https://repositories.lib.utexas.edu//bitstreams/37e93221-1903-4fc6-bb22-7cfca933e612/download

null

Direct laser metal deposition is a means of near net shape processing that offers a number of advantages including rapid prototyping and small lot production. With the LENS (Laser Engineered Net Shape) process [Ref 1], parts are fabricated by creating a laser melted pool into which particles are injected. Fabrication proceeds by moving the work piece, thereby building the structure line by line and layer by layer. In this manner a wide variety of geometries and structures can be fabricated. During fabrication, a complex thermal history is experienced in different regions of the build. These thermal histories include remelting and numerous lower temperature thermal cycles. Furthermore, the use of a finely focused laser to form the rapidly traversing pooL can result in relatively high solidification velocities and cooling rates. Previous work has developed LENS as an advanced manufacturing tool rather than exploiting its potentially unique attributes: real time control of microstructure, tailored material properties at different part locations, the production of graded structures, etc. Very often, however, material properties are not significantly different than those of wrought materials. The. goal of this program is to exploit the unusual thermal environment experienced during fabrication, and the ability to design and vary alloy composition. In this paper we describe this approach using H13 tool steel in which only the thennal fields are varied through changing process parameters to achieve desired properties.

null

Kumar, S.

2020-03-10T17:41:21Z

9/10/08

Mechanical Engineering

null

['https://hdl.handle.net/2152/80239', 'http://dx.doi.org/10.26153/tsw/7258']

eng

2008 International Solid Freeform Fabrication Symposium

Open

Selective Laser Melting

Microstructure and Wear of SLM Materials

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9cdb31de-3ee1-47a9-8ab1-104bb15eb2da/download

null

['Murr, L.E.', 'Gaytan, S.M.', 'Ramirez, D.A.', 'Martinez, E.', 'Martinez, J.L.', 'Hernandez, D.H.', 'Machado, B.I.', 'Medina, F.', 'Wicker, R.B.']

2021-09-30T14:53:02Z

9/23/10

Mechanical Engineering

null

['https://hdl.handle.net/2152/88260', 'http://dx.doi.org/10.26153/tsw/15201']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['materials with controlled microstructural architecture', 'microstructure architecture development', 'additive manufacturing', 'electron beam melting', 'metals', 'alloys', 'solid free-form fabrication']

Microstructure Architecture Development in Metals and Alloys By Additive Manufacturing Using Electron Beam Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/fe50d5bc-4f2b-439a-9089-441921509690/download

University of Texas at Austin

The concept of materials with controlled microstructural architecture (MCMA) to develop and fabricate structural materials with novel and possibly superior properties and performance characteristics is a new paradigm or paradigm extension for materials science and engineering. In the conventional materials science and engineering paradigm, structure (microstructure), properties, processing, and performance features are linked in the development of desirable materials properties and performance through processing methodologies which manipulate microstructures. For many metal or alloy systems, thermomechanical treatment combining controlled amounts of plastic deformation with heat treatment or aging cycles can achieve improved mechanical properties beyond those attainable by conventional processing alone (such as rolling or forging for example) through controlled microstructure development. In this paper we illustrate a new concept involving the fabrication of microstructural architectures by the process development and selective manipulation of these microstructures ideally defining material design space. This allows for the additional or independent manipulation of material properties by additive manufacturing (AM) using electron beam melting (EBM). Specifically we demonstrate the novel development of a carbide (M23C6) architecture in the AM of a Co-base alloy and an oxide (Cu2O) precipitate-dislocation architecture in the AM of an oxygen-containing Cu. While more conventional processing can produce various precipitate microstructures in these materials, EBM produces spatial arrays of precipitate columns or columnar-like features often oriented in the build direction. These microstructural architectures are observed by optical microscopy and scanning and transmission electron microscopy. Prospects for EBM architecture development in precipitation-hardenable Al alloys is also discussed. In the EBM build process using precursor powders, the electron beam parameters (including beam focus, scan speed and sequencing) produce localized, requisite thermodynamic regimes which create or organize the precipitate-related spatial arrays. This feature demonstrates the utility of AM not only in the fabrication of complex components, but also prospects for selective property design using CAD for MCMA development: a new or extended processing-microstructure-property-performance paradigm for materials science and engineering in advanced manufacturing involving solid free-form fabrication (SFF).

null

['Li, Xiaoxuan', 'Wang, Jiwen', 'Augustine, Alvin', 'Shaw, Leon L.', 'Marcus, Harris L.']

2019-10-10T17:08:49Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76174', 'http://dx.doi.org/10.26153/tsw/3263']

eng

2001 International Solid Freeform Fabrication Symposium

Open

['De', 'Densification']

Microstructure Evaluation for Laser Densification of Dental Porcelains

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6f46b07e-c857-4984-8778-d8e603c43751/download

null

The feasibility of dental restorations has been investigated using a multi-materials laser densification (MMLD) process, where dental alloy and porcelain powders are laser densified layer by layer to form solid bodies. The present study focuses on the densification behavior of dental porcelain powders in response to a moving laser source. Effects of the laser processing temperature and the green density of the powder bed on microstructure, distortion, macro-cracks, porosities and phase contents of the laser densified porcelain have been investigated. The condition to generate continuous porcelain bodies from powder compacts have also be studied. It is found that the geometry, composition and density of densified porcelain bodies are strongly affected by the laser processing temperature and the green density of the powder compact.

null

['Avateffazeli, Maryam', 'Khan, Md Faysal', 'Shamsaei, Nima', 'Haghshenas, Meysam']

2023-01-23T13:56:51Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117278', 'http://dx.doi.org/10.26153/tsw/44159']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['A205', 'Al-Cu-Mg-Ag-TiB2', 'laser powder bed fusion', 'fatigue', 'T7 aging']

Microstructure, Mechanical, and Fatigue Properties of a Laser Powder Bed Fused Al-Cu-Mg-Ag-Ti-B (A205) Alloy

Conference paper

https://repositories.lib.utexas.edu//bitstreams/879d1293-5a77-4fd3-8d08-c1dc4bc7df78/download

null

This paper aims at assessing the effect of heat treatment on fatigue behavior of a novel laser-powder-bed-fusion (L-PBF) fabricated Al-Cu-Mg-Ag-Ti-B alloy, known as A205. To this end, L-PBF samples were heat-treated including (i) stress-relieving, and (ii) T7 stabilizing over- aging. Upon printing and post-heat treatments, advanced microstructural characterizations, mechanical property measurements and force-controlled fatigue performance studies were conducted on the samples, systematically. The findings in this paper present useful information for the selection of appropriate heat treatment conditions, to facilitate control of the fatigue behavior in the L-PBF A205 material, which is of great significance for their high-demanding applications in aerospace sectors.

null

['Zimbeck, Walter', 'Pope, Matthew', 'Rice, R.W.']

2018-11-14T20:49:15Z

1996

Mechanical Engineering

doi:10.15781/T24M91W7C

http://hdl.handle.net/2152/70265

eng

1996 International Solid Freeform Fabrication Symposium

Open

['UV flood lamp', '3D printing', 'SFF']

Microstructures and Strengths of Metals and Ceramics made by Photopolymerbased Rapid Prototyping

Conference paper

https://repositories.lib.utexas.edu//bitstreams/0bd8cbd7-647c-4a60-b324-00eadb1a0a33/download

null

Metal and ceramic flexure specimens were fabricated using a photopolymer-based rapid prototyping technique. Photosensitive resins (inks) were produced by dispersing 50 - 55 vol% metal or ceramic powders in a photopolymer resin. Laminates 0.2" thick were built up by repeated application oflayers 3 - 10 mils thick followed by curing under a UV flood lamp with photomasks. The layered samples were thermally processed to remove the photopolymer binder and sintered to high density. Densities, microstructural characterization and flexure strengths are reported for silicon nitride, alumina, zirconia, stainless steel, and tungsten.

null

['Buls, Sam', 'Vleugels, Jef', 'Van Hooreweder, Brecht']

2021-11-16T15:08:23Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90307', 'http://dx.doi.org/10.26153/tsw/17228']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['technical ceramics', 'ceramics', 'direct processing', 'microwave assisted selective laser melting']

Microwave Assisted Selective Laser Melting of Technical Ceramics

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a047b73f-844e-44b4-8992-7a35c8f33700/download

University of Texas at Austin

Direct processing of near fully dense technical ceramics is not possible with conventional additive manufacturing (AM) processes due to the very high temperatures that are required. Therefore, indirect AM approaches are often used. These indirect processes show great potential but require extensive post processing (e.g. debinding and sintering) leading to shrinkage, limited geometrical accuracy and eventually limiting overall part quality. To overcome these limitations, this paper presents a novel Microwave Assisted Selective Laser Melting process that enables direct processing of technical ceramics.

null

['Clark, N.', 'Lacan, F.', 'Porch, A.']

2021-11-02T18:27:59Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89860

eng

2017 International Solid Freeform Fabrication Symposium

Open

['microwave', 'nylon', 'perturbation', 'permittivity', 'powder', 'polyamide', 'laser sintering']

Microwave Measurements of Nylon-12 Powder Ageing for Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/93b2b36e-6c53-48ea-888d-f66f325f81b3/download

University of Texas at Austin

With repeated recycling, nylon powders used in Selective Laser Sintering are known to degrade and ultimately cause mechanical performance and surface finish deterioration in produced parts. In order to maintain consistent production and to reduce cost by minimising waste powder, it is desirable to monitor this degradation. However, any techniques used must be inexpensive, quick and simple in order to maintain industrial relevance; dielectric measurements by microwave cavity perturbation can offer these advantages. Here, samples are taken from a working SLS machine and their permittivity measured using microwave cavity perturbation operating around 2.5 GHz. A 2% reduction in effective dielectric constant and an 8% reduction in effective dielectric loss is observed between new powder and recycled feedstock. Furthermore, in-situ measurements simulating build chamber conditions show a similar trend.

null

['Krishnanand, L.', 'Manmadhachary, A.', 'Ravi Kumar, Y.']

2021-10-18T20:58:05Z

2014

Mechanical Engineering

null

https://hdl.handle.net/2152/89244

eng

2014 International Solid Freeform Fabrication Symposium

Open

['CT', 'partial volume effect', 'volumetric error', 'CT image construction', 'ANOVA']

Minimization of Volumetric Errors in CAD Medical Models Using 64 Slice Spiral CT Scanner

Conference paper

https://repositories.lib.utexas.edu//bitstreams/845fb874-dfeb-4c5c-9e7e-121d89a70d44/download

University of Texas at Austin

Sixty four slice spiral Computed Tomography (CT) scanner is one of the advanced CT scanners to capture the large volume of tissues and improved longitudinal resolution. The CT images are used to develop a 3-Dimensional (3D) Computer Aided Design (CAD) medical model. While developing a 3D CAD medical model volumetric errors occur due to partial volume or volume averaging effect. In order to study, various CT image construction parameters were considered to minimize the volumetric errors in 3D CAD medical models, a human dry mandible has been selected as a phantom. A Taguchi technique was used to find optimal CT image construction parameters. A L9 orthogonal array was used to optimize the CT image construction parameters constituting slice thickness, slice increment and Field of View (FOV) while performing CT image construction. The resultant optimal parameters are scrutinized using analysis of variance (ANOVA) method for its influence on the CT image construction. In this work, it has been found that there is a volumetric error of a 3D CAD medical model (STL file) from CT images of a dry mandible was 1978 mm3 (6.11%).

null

['Chan, C K', 'Tan, S T']

2019-03-12T16:13:52Z

1999

Mechanical Engineering

null

['https://hdl.handle.net/2152/73594', 'http://dx.doi.org/10.26153/tsw/736']

eng

1999 International Solid Freeform Fabrication Symposium

Open

['bounding box', 'iterative method']

A Minimum Bounding Box Algorithm and its Application to Rapid Prototyping

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6e6ef6c2-b191-4947-b32e-dc46d5f49bb6/download

null

This paper describes a method for determining the minimum bounding box of an arbitrary solid. The method simplifies the complex three-dimensional problem by projecting the solid onto the three principal planes and makes use ofthe projected contours for analysis. The orientations of the contours are determined by rotating them within a specific angle range. These orientations are then used to approximate the orientation of the solid so that its bounding box volume is minimised.

null

['Grant, Lynnora O.', 'Alameen, Magdi B.', 'Carazzone, J. Reid', 'Higgs, C. Fred III', 'Cordero, Zachary C.']

2021-11-09T14:42:05Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90083', 'http://dx.doi.org/10.26153/tsw/17004']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['laser sintering', 'binder jetting', 'reactive binder', 'distortion', '3D printing', 'ceramics']

Mitigating Distortion During Sintering of Binder Jet Printed Ceramics

Conference paper

https://repositories.lib.utexas.edu//bitstreams/915136a3-3415-4297-ba94-0f24787c9418/download

University of Texas at Austin

Sintering increases the strength of binder jet 3D printed green bodies through densification, but with the potential cost of distortion due to creep. In this work, we determine how a reactive binder affects such distortion during sintering of titanium dioxide green bodies. The binder decomposes to form nanocrystalline interparticle necks during the early stages of the sintering process. We first characterize the decomposition of the reactive binder through thermogravimetry, differential scanning calorimetry, and x-ray diffraction. Next, we elucidate the effect of this precursor on the shrinkage of cylindrical parts using dilatometry experiments, and observe the deflection of sintering beams using in situ imaging. These experiments show that the precursor dramatically suppresses creep during sintering, demonstrating a potential solution for increasing the dimensional accuracy of the binder jet 3D printing process.

null

['Marques, Lucas Galvan', 'Williams, Robert Austin', 'Zhou, Wenchao']

2021-11-04T14:41:46Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89972

eng

2017 International Solid Freeform Fabrication Symposium

Open

['mobile 3D printer', 'filament extrusion printhead', 'Internet', 'cooperative 3D printing']

A Mobile 3D Printer for Cooperative 3D Printing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2c0501ab-203a-4e74-b19d-63e3b7c7460b/download

University of Texas at Austin

Cooperative 3D printing is an emerging technology that aims to provide scalability to 3D printing by enabling thousands of printhead-carrying mobile robots to cooperate on a single printing job and to integrate pre-manufactured components during the 3D printing process. At the core of the cooperative 3D printing platform is a mobile robot that can carry different printhead or a gripper. In this paper, we present a mobile 3D printer with a filament extrusion printhead that can be controlled over the Internet. First, we designed a compact mobile 3D printer with an extrusion printhead and four omnidirectional wheels. A wireless communication interface is also developed to send commands to and receive information from the mobile 3D printer. Successful prints have been demonstrated with two developed mobile 3D printers printing cooperatively, which shows the promise of cooperative 3D printing.

null

['Asiabanpour, B.', 'Um, D.', 'Sriraman, V.', 'Tseng, A.', 'Mata, J.', 'Wahed, N.']

2020-02-20T19:23:47Z

8/23/05

Mechanical Engineering

null

https://hdl.handle.net/2152/80041

eng

2005 International Solid Freeform Fabrication Symposium

Open

Mobile Paving System

Mobile Paving System (MPS): A New Large Scale Freeform Fabrication Method

Conference paper

https://repositories.lib.utexas.edu//bitstreams/071942f4-ab67-4a91-84e9-c2822b0ff62d/download

null

In the last decade, significant opportunities for automation have been identified in the area of construction. Soaring labor and material costs have driven multiple research efforts in construction automation. In this paper, we present a novel means for construction automation that involves the fusion of the rapid prototyping, controls and mechatronics technologies. The resultant autonomous construction mechanism has been designed for commercial applications. Mobile Paving System (MPS) is a new freeform fabrication process which is capable of rapidly producing variable profiles such as curbs and sidewalks out of materials like cement and asphalt. Path generation and guidance of the construction operation is controlled by a mobile robot. This article presents an overview of research and development efforts that are aimed at establishing the feasibility and the potential of the process.

null

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

2021-11-08T22:48:24Z

2017

Mechanical Engineering

null

['https://hdl.handle.net/2152/90063', 'http://dx.doi.org/10.26153/tsw/16984']

eng

2017 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'cooperative 3D printing', 'robot gripper', 'hybrid production']

A Mobile Robot Gripper for Cooperative 3D Printing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e9805dc4-ced4-4c09-b1ba-2ef94b14dcc8/download

University of Texas at Austin

Cooperative 3D printing is an emerging technology that aims to overcome several limitations of contemporary 3D printing (e.g., print size, cost, complexity) by allowing multiple mobile 3D printers (or printhead-carrying mobile robots) to work simultaneously on a single print job. In particular, one challenge of 3D printing is the inability to incorporate pre-manufactured components in a structure without human intervention. In this paper, we present a mobile robot gripper that can work with other mobile 3D printers to pick and place pre-manufactured components into a 3D printed structure during the printing process. First, we designed a simple gripper using a rack and pinion actuator that can be driven by a single stepper motor like a regular extrusion printhead. Next, a mobile robot gripper is developed with the designed gripper mechanism. Finally, we tested the mobile robot gripper for picking and placing objects using G-code commands. Results show the mobile robot gripper can successfully pick and place pre-manufactured components into a 3D printed structure. This development will potentially enable autonomous hybrid manufacturing that combines 3D printing and traditional manufacturing to improve the quality and capability for manufacturing complex products.

null

['Pribe, Joshua D.', 'West, Brian M.', 'Gegel, Michelle L.', 'Hartwig, Troy', 'Lunn, Toby', 'Brown, Ben', 'Bristow, Douglas A.', 'Landers, Robert G.', 'Kinzel, Edward C.']

2021-10-26T18:13:52Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89547

eng

2016 International Solid Freeform Fabrication Symposium

Open

['modal response', 'validation technique', 'metal parts', 'selective laser melting', 'frequency response function', 'FRF']

Modal Response as a Validation Technique for Metal Parts Fabricated with Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6129fd15-cc52-46d3-b18c-24c72ce385c1/download

University of Texas at Austin

This paper investigates modal analysis as a validation technique for additively manufactured parts. The Frequency Response Function (FRF) is dependent on both the geometry and the material properties of the part as well as the presence of any defects. This allows the FRF to serve as a “fingerprint” for a given part of given quality. Once established, the FRF can be used to qualify subsequently printed parts. This approach is particularly attractive for metal parts, due to the lower damping as well as use in high-value applications where failure is unacceptable. To evaluate the efficacy of the technique, tensile specimens are printed with a Renishaw AM250, the modal response of these parts is characterized prior to tensile testing, and the FRFs are compared to their engineering metrics for parts printed with both nominal and off-nominal parameters. Numerical modeling is used to understand the modal structure, and the possibility of defect prognosis is also explored by comparing the measured response to simulation results.

null

['Chahal, Vedant', 'Taylor, Robert M.']

2021-11-09T19:46:34Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90144', 'http://dx.doi.org/10.26153/tsw/17065']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['residual stress', 'maraging steel 300', 'model development', 'laser metal 3D printing', 'selective laser melting', 'design of experiments']

Model Development for Residual Stress Consideration in Design for Laser Metal 3D Printing of Maraging Steel 300

Conference paper

https://repositories.lib.utexas.edu//bitstreams/eda19017-2fd2-4e9f-9a5b-33ebdbaee331/download

University of Texas at Austin

Design optimization of laser metal 3D printed structural components requires prediction of build-process induced residual stresses that vary with part geometry and affect distortion and support requirements during the build. Finite element residual stress state evaluation is not feasible within the computational constraints of iterative optimization. Alternatively, a simplified theoretical model is presented for predicting the residual stresses induced during Selective Laser Melting of maraging steel. Furthermore, a Design of Experiments (DOE) approach is implemented to verify the theoretical model and develop a response surface suitable for design optimization. The DOE uses cantilever geometry with length, thickness, and fillet radius as variables and shows overhang length to have the greatest influence on residual stresses. Geometries with high stiffness lead to lower deformations and tend to retain high stresses. The presented model can predict the trend of residual stresses for different geometries and can be used in shape optimization.

null

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

2020-02-24T14:56:38Z

8/26/05

Mechanical Engineering

null

['https://hdl.handle.net/2152/80076', 'http://dx.doi.org/10.26153/tsw/7097']

eng

2005 International Solid Freeform Fabrication Symposium

Open

Solid Freeform Fabrication

A Model for Error Propagation in the Surface Profile for Solid Freeform Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/60d45401-1f0c-4cbe-b33e-05f57bfc84b0/download

null

['Sun, Ming-shen', 'Nelson, Christian', 'Beaman, Joseph J.', 'Barlow, Joel J.']

2018-04-12T18:22:09Z

1991

Mechanical Engineering

doi:10.15781/T29W09G38

http://hdl.handle.net/2152/64279

eng

1991 International Solid Freeform Fabrication Symposium

Open

['Powder bed', "Frenkel's model", 'SSL']

A Model for Partial Viscous Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5bfa0356-d008-4cd1-8332-67a5d0f3b3d9/download

null

A mathematical model describing the sintering rate of a viscous material powder bed is presented. This model assumes that the powder bed is composed of cubic packed, equal-size spherical particles. The sintering rate equation is derived in terms of a unit cell dimension or the relative density of a powder bed. A mathematical factor, fraction of sintering, is introduced to explain the phenomena of partial sintering. Key words: model, viscous sintering.

null

['Watanabe, N.', 'Shofner, M.L.', 'Treat, N.', 'Rosen, D.W.']

2021-11-01T22:50:36Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89788

eng

2016 International Solid Freeform Fabrication Symposium

Open

['residual stress', 'part warpage', 'polypropylene', 'material extrusion']

A Model for Residual Stress and Part Warpage Prediction in Material Extrusion with Application to Polypropylene

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3af82ce8-1e6e-44ad-8b85-b769385adbcb/download

University of Texas at Austin

The layer-by-layer fabrication procedure causes residual stresses to accumulate due to the repetition of heating and cooling during the material extrusion process. In this study, residual stress and part warpage of a polypropylene copolymer are investigated. The effects of adjusting process variable settings, such as deposition temperature, deposition speed, and layer height, on part warpage are analyzed computationally and experimentally. Material extrusion process simulation models that are capable of predicting the temperature distributions, deposited filament shapes, and residual stresses of fabricated parts have been developed. These models are used to predict the warpages and deformations of the fabricated parts; these predictions are compared with experimental results to evaluate the models’ efficacy. Insights are gained on the effects of particulate inclusions on the residual stress and warpage behaviors of polypropylene copolymer.

null

['Sui, Chao', 'Zhou, Wenchao']

2023-01-27T14:18:15Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117337', 'http://dx.doi.org/10.26153/tsw/44218']

eng

2022 International Solid Freeform Fabrication Symposium

Open

['piezo inkjet', 'printing speed', 'drop-on-demand (DOD)', 'driving signal', 'model']

A Model for the Effects of Driving Signal on Piezoelectric Inkjet Printing Speed

Conference paper

https://repositories.lib.utexas.edu//bitstreams/085fe5dd-7d67-4bf3-b4ed-669263dc7aa0/download

null

Piezo drop-on-demand (DOD) inkjet is a non-contact and direct forming technique for pattern fabrication, which has been widely used in additive manufacturing and other industrial applications. It is known that the ink properties and the waveform of the driving signal play a significant role in droplet ejection behavior. In this paper, we present a model for the droplet formation dynamics from a single nozzle with a bipolar driving signal, which provides a quantitative relationship between the waveform of the driving signal and the average jetting velocity at the nozzle exit, droplet ejection frequency, droplet volume, and printing speed. An experimental setup is developed for calibration and validation of the model. Results show the model agrees well with experiments and can be used to predict inkjet printing speed based on the parameters of the driving signal.

null

['Das, Suman', 'Chung, Haseung']

2019-10-18T15:28:40Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76239', 'http://dx.doi.org/10.26153/tsw/3328']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Sintering

A Model of Laser-Powder Interaction in Direct Selective Laser Sintering of Metals

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b50adf57-fc89-4de0-a681-27d73a793839/download

null

We present a simple one-dimensional model that describes the physical mechanisms of heat transfer, melting and resolidification taking place during and after the interaction of a laser beam with a bed of pure metal powder. The physical model describing this situation is based on the classical Stefan problem with appropriately chosen boundary conditions to reflect direct selective laser sintering of metals. A numerical model based on the finite volume method is developed to perform computations for two beam diameters, three beam speeds and for constant, step and ramp laser power input profiles. The results of these computations show the influence of laser beam diameter, laser power input rate and input duration on the melt interface velocity and location, and temperature. Scaling laws for time to reach maximum melt depth and total meltresolidification time are derived. Comparisons of the temperature histories for the three power input profiles are described.

null

['Klosterman, Donald', 'Chartoff, Richard', 'Flach, Lawrance', 'Bryant, Eric']

2019-09-23T16:49:50Z

2000

Mechanical Engineering

null

['https://hdl.handle.net/2152/75967', 'http://dx.doi.org/10.26153/tsw/3066']

eng

2000 International Solid Freeform Fabrication Symposium

Open

Fabrication

Model-Based Control of Cure Distribution in Polymer Composite Parts Made by Laminated Object Fabrication (LOF) 409

Conference paper

https://repositories.lib.utexas.edu//bitstreams/fd4471c3-4bbf-408a-bd0a-0b818e0c33c7/download

null

A mathematical heat transfer model was used to investigate process control strategies for making thermoset polymer composite materials by Laminated Object Fabrication (LOF). The temperature of the laminator was manipulated in order to control the uniformity and overall level of cure through the thickness of a 20-layer part. When the laminator temperature was held constant throughout the LOF build process, as is normally the case in practice, the model predicted that the resulting panel would have a steep cure gradient from top to bottom. This was considered to be undesirable. The model was then used in conjunction with an optimization algorithm to determine a temperature program for the laminator which would result in panels with a more desirable spatial cure profile (i.e. constant). Computer model simulations demonstrated that it should be feasible to control both the level and distribution of cure in thermoset composite panels layed-up with LOF by simply manipulating the laminator temperature with simple and realistic heating schedules.

null

['Mignatti, M.A.', 'Campbell, M.I.', 'Ruizpalacios, R.', 'Wood, K.L.', 'Beaman, J.J.']

2019-11-21T18:19:21Z

2003

Mechanical Engineering

null

['https://hdl.handle.net/2152/78555', 'http://dx.doi.org/10.26153/tsw/5611']

eng

2003 International Solid Freeform Fabrication Symposium

Open

Direct-Write

Modeling and Characterization of a Novel, Low-Cost, Direct-Write Waveguide

Conference paper

https://repositories.lib.utexas.edu//bitstreams/69808ec2-00d6-4485-9e3b-9257373a55fe/download

null

Both the current long-term telecommunication trends toward optical networking and the recent growth in information bandwidth have pushed the necessity for improved optical communications. Our fabrication approach, which leverages our expertise in solid freeform fabrication in conjunction with sol-gel technology, has advantages over these other methods because of the inherent benefits of using a direct-write philosophy, such as design flexibility and minimal post-processing. However, fabrication of such novel optical components requires extensive knowledge of their light guidance capabilities. This paper will show the technical issues involved in both modeling and characterizing small optical components fabricated by locally densifying sol-gels in a modified directwrite process.

null

['Basak, Amrita', 'Acharya, Ranadip', 'Das, Suman']

2021-10-21T18:09:07Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89414

eng

2015 International Solid Freeform Fabrication Symposium

Open

['microstructure evolution', 'single-crystal alloys', 'scanning laser epitaxy']

Modeling and Characterization of Microstructure Evolution in Single-Crystal Superalloys Processed through Scanning Laser Epitaxy

Conference paper

https://repositories.lib.utexas.edu//bitstreams/33ee570e-19fc-41a8-b58b-3bd91baefadb/download

University of Texas at Austin

This paper focuses on microstructure evolution in single-crystal alloys processed through scanning laser epitaxy (SLE); a metal powder-bed based additive manufacturing technology aimed at the creation of equiaxed, directionally-solidified or single-crystal structures in nickel-base superalloys. Galvanometer-controlled movements of the laser and high-resolution raster scanning result in improved control over the melting and solidification processes in SLE. Characterization of microstructural evolution as a function of the complex process physics in SLE is essential for process development, control and optimization. In this paper an ANSYS CFX based transient flow-thermal model has been developed to simulate microstructure characteristics for single-crystal superalloys such as CMSX-4 and René N5. Geometrical parameters and melt pool properties are used to estimate the resulting solidification microstructure. Microstructural predictions are compared to experimental metallography and reasonably good agreement is achieved.

This work is sponsored by the Office of Naval Research through grants N00014-11-1-0670 and N00014-14-1-0658.

null

['Subedi, Saroj', 'Ware, Henry Oliver Tenadooah']

2024-03-26T17:14:21Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124381', 'https://doi.org/10.26153/tsw/50989']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['digital light processing', 'illumination', 'wavelength', 'additive manufacturing']

MODELING AND CORRECTING ILLUMINATION INHOMOGENEITY OVER MULTIPLE DLP ILLUMINATION INTENSITIES FOR BETTER FABRICATION ACCURACY

Conference paper

https://repositories.lib.utexas.edu//bitstreams/6e392d72-d9ec-4368-b34f-217a6a98569d/download

University of Texas at Austin

Within custom Digital Light Processing (DLP) systems, various small issues either in the optical assembly or with the DMD can lead to non-uniform illumination at the curing interface. This inhomogeneity leads to inaccurate dimensions of fabricated features over the full print area. To remedy this in our system, we have explored the relationship between LED output illumination, divided the illuminated area into a regional mesh, measured the light intensity and grayscale values over the mesh to obtain region-specific grayscale mask adjustments for illumination-leveling. This process involves producing grayscale mask by quantifiably balancing the light intensity values over build area and thus obtaining more uniform printed features. We compared the dimensional accuracy of features printed using full white pixel value images for 250µm features and those obtained using illumination-leveling grayscale processed images. Our results demonstrate the effectiveness of our method to obtain dimensionally accurate features, thanks to the achieved uniform illumination.

null

['Jackson, Todd R.', 'Patrikalakis, Nicholas M.', 'Sachs, Emanuel M.', 'Cima, Michael J.']

2019-02-20T17:21:31Z

1998

Mechanical Engineering

null

['https://hdl.handle.net/2152/73455', 'http://dx.doi.org/10.26153/tsw/607']

eng

1998 International Solid Freeform Fabrication Symposium

Open

['LCC', '3D Printing']

Modeling and Designing Components with Locally Controlled Composition

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c5234484-6f7d-4741-859b-88909baa9bd0/download

null

SFF processes have demonstrated the ability to produce parts with locally controlled composition. In the limit, processes such as 3D Printing,cancreate parts with composition control on thelength scaleiof 100 microns.ToexploitthispC)tential,~e\\ZJnethodsto rnod~l, exchange, and process parts.with local composition needtobe.deyeloped..... Anapproachtc) modeling a part's geometty,.topology, and composition will be presented.· This.approachis based on sUbdividing the solidmodel into sub-regions and associating analytic composition blending functions \\lith each region. These blending functions definethe composition throughout the model as mixtures ofthe primary materials available to·the SEF machine. Various design tools will also be presented, for example, specification of com~ositionasa function of the distance from the surface of a part. Finally,the role of design rules specifying maximum concentrations and concentration.gradients will be discussed.

null

['Li, W.', 'Zhang, J.W.', 'Karnati, S.', 'Zhang, Y.L.', 'Liou, F.', 'Newkirk, J.', 'Taminger, K.M.B.', 'Seufzer, W.L.']

2021-10-26T18:58:45Z

2016

Mechanical Engineering

null

https://hdl.handle.net/2152/89556

eng

2016 International Solid Freeform Fabrication Symposium

Open

['functionally gradient material', 'pre-mixed multi-powder', 'FGM composition', 'numerical modeling']

Modeling and Experimental Investigation of Pre-Mixed Multi-Powder Flow in Fabricating Functional Gradient Material by Laser Metal Deposition Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/f8580f8a-ef50-4852-8495-1bd4e9fa4fe1/download

University of Texas at Austin

Laser Metal Deposition (LMD) is an effective process to fabricate Functionally Gradient Material (FGM) from pre-mixed powders. Since the supplied multi-powder directly affects the deposited FGM’s composition, investigation on Pre-Mixed Multi-Powder (PMMP) flow during LMD is greatly needed. This paper presents a comprehensive numerical PMMP flow model. By solving discrete particle force balance equations coupled with continuity equations and momentum equations for carrier gas, the dynamic behavior of PMMP flow through powder feeder pipe and out of nozzle was calculated. To verify modeling results, pre-mixed Cu and 4047 Al powder was transported and patterned in an epoxy resin coating after exiting nozzle. The distribution of exiting pre-mixed powder was plotted by quantifying the volume percentages of different powders. The gathered distribution data was used to estimate the exiting pre-mixed powder’s composition, and finally validate modeling results.

null

['Bryant, Frances D.', 'Leu, Ming C.']

2021-09-23T21:52:31Z

9/10/08

Mechanical Engineering

null

['https://hdl.handle.net/2152/88031', 'http://dx.doi.org/10.26153/tsw/14972']

eng

2008 International Solid Freeform Fabrication Symposium

Open

['Rapid Freeze Prototyping', 'support material', 'mechanical engineering']

Modeling and Experimental Results of Concentration with Support Material in Rapid Freeze Prototyping

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7096937e-43f1-496d-909d-66d0d95d36df/download

null

Ice structures with complex geometries and overhung areas are created by the Rapid Freeze Prototyping (RFP) process in a sufficiently cool environment by freezing water into ice as the main material in conjunction with a eutectic dextrose-water solution as the sacrificial support material. The supported areas in an ice structure are removed via an increase in temperature in a separate environment after the structure is completely fabricated. To understand to what extent these two materials mix during fabrication, two methods of modeling the concentration changes that occur near the interface of the main and support materials have been developed. The simulation results based on these models along with some experimentally measured data are presented in this paper.

null

['Anam, Md Ashabul', 'Pal, Deepankar', 'Stucker, Brent']

2021-10-11T20:38:21Z

2013

Mechanical Engineering

null

['https://hdl.handle.net/2152/88636', 'http://dx.doi.org/10.26153/tsw/15570']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['Selective Laser Melting', 'Inconel 625', 'nickel-based superalloy', 'process parameters', 'dislocation density based crystal plasticity finite element model']

Modeling and Experimental Validation of Nickel-based Super Alloy (Inconel 625) Made Using Selective Laser Melting

Conference paper

https://repositories.lib.utexas.edu//bitstreams/80e87820-175a-47ae-94a3-71d6d98e880a/download

University of Texas at Austin

The formation of constituent phases in Selective Laser Melting of Inconel 625 is a function of local temperatures, hold times at those temperatures, local cooling rates and local compositions in the melt pool. These variables are directly correlated with input process parameters such as beam power, scan speed, hatch spacing, beam diameter and thermo-mechanical characteristics of the powder bed. The effect of these process parameters must be understood in order to properly control the machines and predict the properties of parts being fabricated. To understand the effects, IN625 coupons using eight different sets of processing parameters have been fabricated and microstructure and mechanical properties were compared. These properties will be then used to validate a dislocation density based crystal plasticity finite element model (DDCP-FEM).

null

['Huang, Pu', 'Deng, Dongping', 'Chen, Yong']

2021-10-07T17:43:49Z

2013

Mechanical Engineering

null

['https://hdl.handle.net/2152/88492', 'http://dx.doi.org/10.26153/tsw/15426']

eng

2013 International Solid Freeform Fabrication Symposium

Open

['heterogeneous object', 'material design', 'stereolithography', 'functional grading material', 'process planning']

Modeling and Fabrication of Heterogeneous Three-Dimensional Objects Based on Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/b8348412-bf5e-4f47-a693-f7d6e427b5fc/download

University of Texas at Austin

Heterogeneous object modeling and fabrication has been studied in the past few decades. Recently the idea of digital materials has been demonstrated by using Additive Manufacturing (AM) processes. Our previous study illustrated that the mask-image-projection based Stereolithography (MIP-SL) process is promising in fabricating such heterogeneous objects. In the paper, we present an integrated framework for modeling and fabricating heterogeneous objects based on the MIP-SL process. Our approach can achieve desired grading transmission between different materials in the object by considering the fabrication constraints of the MIP-SL process. The MIP-SL process planning of a heterogeneous model and the hardware setup for its fabrication are also presented. Test cases including physical experiments are performed to demonstrate the possibility of using heterogeneous materials to achieve desired physical properties. Future work on the design and fabrication of objects with heterogeneous materials is also discussed.

null

['Liou, Frank', 'Fan, Zhiqiang', 'Pan, Heng', 'Slattery, Kevin', 'Kinsella, Mary', 'Newkirk, Joseph', 'Chou, Hsin-Nan']

2020-03-09T14:42:52Z

9/4/07

Mechanical Engineering

null

['https://hdl.handle.net/2152/80188', 'http://dx.doi.org/10.26153/tsw/7207']

eng

2007 International Solid Freeform Fabrication Symposium

Open

direct laser deposition

Modeling and Simulation of a Laser Deposition Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c63c2bd5-44f2-40f3-87f6-37bc95d697f7/download

null

A laser deposition process involves the supply of metallic powders into a laser-heated spot where the powder is melted and forms a melt puddle which quickly solidifies into a bead. In order to design an effective system, the laser beam, the powder beam, and their interactions need to be fully understood. In this paper, the laser-material interaction within the melt pool is reported using a multi-scale model: a macroscopic model to model mass, heat, and momentum transfer. Experiments were also conducted to validate the simulation model.

null

['Bryant, Frances D.', 'Leu, Ming C.']

2020-03-09T14:53:10Z

9/4/07

Mechanical Engineering

null

['https://hdl.handle.net/2152/80190', 'http://dx.doi.org/10.26153/tsw/7209']

eng

2007 International Solid Freeform Fabrication Symposium

Open

['Rapid Freeze Prototyping', 'solid freeform fabrication process']

Modeling and Validation of Temperature and Concentration for Rapid Freeze Prototyping

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7abe8d9e-ad94-418a-aeee-d9a6e46229e8/download

null

Rapid Freeze Prototyping is a solid freeform fabrication process that uses water as the main build material in a cold environment to create three-dimensional parts. A eutectic sugar-water solution (C6H12O6 – H2O) has been used as a sacrificial material in order to create complex 3D parts with features such as overhangs. A study of the interaction of the build and support materials is presented in this paper. The temperature of both materials during deposition and subsequent cooling is modeled using a semi-empirical model and a theoretical model. A concentration model is used to predict the concentration in the fabricated parts around the interface of the two materials with predicted temperatures as input. Experiments are conducted to validate both the temperature and concentration models.

null

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

2020-03-02T15:42:12Z

9/14/06

Mechanical Engineering

null

['https://hdl.handle.net/2152/80137', 'http://dx.doi.org/10.26153/tsw/7158']

eng

2006 International Solid Freeform Fabrication Symposium

Open

SolidFreeform-Fabrication

Modeling and Verification of Error Propagation in Integrated Additive/Subtractive Multi-Directional Direct Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/014eb756-d0af-4bd9-a0ea-ecebf26c3a44/download

null

Integrated additive-subtractive manufacturing, when applied in the framework of SolidFreeform-Fabrication (SFF) allows the fabrication of functional parts on single platform, directly from its computer model. Reduction in process complexity and total processing steps is ensured by multi-directional material deposition and machining. However, due to shift in the datum location in reorientation steps and sequential addition of material in the form of layers, the CAD process intent is not exactly replicated. This leads to inclusion of dimensional errors. Machining in order to eliminate the errors as frequent as layer deposition is highly expensive and can be avoided by estimation of errors and varying process parameters, and/or performing machining after a set of layers are deposited. This paper proposes a state space model for modeling the error propagation due to linear as well as angular variation in the datum. The model is based on identification of possible sources of error, mechanism of error inclusion and influence of process parameters. An experiment performed to determine parameters of error modeling has been reported.

null

['Pierce, Jason B.', 'Smith, Douglas E.']

2024-03-26T17:16:28Z

2023

Mechanical Engineering

null

['https://hdl.handle.net/2152/124382', 'https://doi.org/10.26153/tsw/50990']

en_US

2023 International Solid Freeform Fabrication Symposium

Open

['computational fluid dynamics', 'discrete element modeling', 'carbon fiber', 'suspension dynamics', 'additive manufacturing']

MODELING CARBON FIBER SUSPENSION DYNAMICS FOR ADDITIVE MANUFACTURING POLYMER MELT FLOWS

Conference paper

https://repositories.lib.utexas.edu//bitstreams/9fe49a38-cd58-4d1b-b5cb-fb2edc2209e9/download

University of Texas at Austin

The addition of short carbon fibers to the feedstock of large-scale polymer extrusion/deposition additive manufacturing results in significant increases in mechanical properties dependent on the fiber distribution and orientation in the beads. In order to analyze those factors, a coupled computational fluid dynamics (CFD) and discrete element modeling (DEM) approach is developed to simulate the behavior of fibers in an extrusion/deposition nozzle flow after calibrations in simple shear flows. The DEM model uses bonded discrete particles to make up flexible and breakable fibers that are first calibrated to match Jeffery’s orbit and to produce interactions that are consistent with Advani-Tucker orientation tensor predictions. The DEM/CFD model is then used to simulate the processing of fiber suspensions in the variable flow and geometries present in extrusion/deposition nozzles. The computed results provide enhanced insight into the evolution of fiber orientation and distribution during extrusion/deposition as compared to existing models through individual fiber tracking over time and space on multiple parameters of interest such as orientation, flexure, and contact forces.

null

['Jariwala, Amit S.', 'Ding, Fei', 'Boddapati, Aparna', 'Breedveld, Victor', 'Grover, Martha', 'Henderson, Clifford L.', 'Rosen, David W.']

2021-09-30T18:43:27Z

9/23/10

Mechanical Engineering

null

['https://hdl.handle.net/2152/88275', 'http://dx.doi.org/10.26153/tsw/15216']

eng

2010 International Solid Freeform Fabrication Symposium

Open

['stereolithography', 'additive manufacturing', '2D photopolymerization model', 'oxygen inhibition', 'oxygen diffusion']

Modeling Effects of Oxygen Inhibition in Mask Based Stereolithography

Conference paper

https://repositories.lib.utexas.edu//bitstreams/33e36670-4d7a-4512-b786-6ddf97505cf2/download

University of Texas at Austin

Stereolithography (SL) is an additive manufacturing process in which liquid photopolymer resin is cross-linked and converted to solid with a UV laser light source. Traditional models of SL processes do not consider the complex chemical reactions and species transport occurring during photopolymerization and, hence, are incapable of accurately predicting resin curing behavior. In this paper, a 2D photopolymerization model based on ordinary differential equations is presented that incorporates the effects of oxygen inhibition and diffusion during the polymerization process. This model accurately predicts the cured part height when compared to experiments conducted on a mask based stereolithgraphy system. The simulated results also show the characteristic edge curvature as seen in experiments. Parametric studies were conducted to investigate the possibilities to improve the accuracy of the model for predicting the edge curvature.

null

['Boddu, Mallikharjuna R.', 'Thayalan, Vishnu P.', 'Landers, Robert G.']

2019-11-20T16:10:48Z

2003

Mechanical Engineering

null

['https://hdl.handle.net/2152/78467', 'http://dx.doi.org/10.26153/tsw/5552']

eng

2003 International Solid Freeform Fabrication Symposium

Open

Aided Manufacturing

Modeling for the Control of the Laser Aided Manufacturing Process(LAMP)

Conference paper

https://repositories.lib.utexas.edu//bitstreams/3f60edb1-7bfd-4c03-9c56-f46aad902bf3/download

null

Many state–of–the–art Rapid Prototyping (RP) technologies adopt lasers to fabricate 3–D solid parts by material deposition in layers. The ability of these RP technologies to control the process requires a thorough understanding of the process mechanics. This paper presents the analysis of an analytical, dynamic model explaining the complex phenomenon of Laser Aided Manufacturing Process (LAMP). The equilibrium of the dynamic model is analyzed and dynamic simulations are performed to determine its stability characteristics. This model forms the basis for the real–time control of the LAMP.

The authors gratefully acknowledge the financial support of the National Science Foundation (DMI–9871185), Society of Manufacturing Engineers (#02022–A), Missouri Research Board, and UMR’s Intelligent Systems Center.

null

['Wu, Yan', 'Yang, Li']

2021-11-04T19:21:43Z

2017

Mechanical Engineering

null

['https://hdl.handle.net/2152/90008', 'http://dx.doi.org/10.26153/16929']

eng

2017 International Solid Freeform Fabrication Symposium

Open

['2D lattice structures', 'unit cell', 'deformation', 'fracture behavior', 'crack propagation', 'additive manufacturing']

Modeling of Crack Propagation in 2D Brittle Finite Lattice Structures Assisted by Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/2600499f-969f-40ea-8411-50a8d24a9079/download

University of Texas at Austin

The failure characteristics of lattice structures are of significant importance in various lightweight applications such as aerospace and biomedicine. In this study, several 2D lattice structures with different number of unit cells that represent different geometrical characteristics and deformation mechanisms were investigated for their fracture behaviors. The fracture characteristic of the cellular samples was studied experimentally through tensile testing. The fracture propagation patterns of different lattice designs were investigated by high-speed camera, and consequently analyzed via analytical model in order to evaluate the effect of finite unit cells on the fracture characteristics of these cellular structures. The results were further compared with the classic cellular fracture theory by Gibson and Ashby. The comparison results suggest that for small number of unit cells designs the homogenized fracture model does not provide accurate crack propagation predictions.

null

['Turner, Irem Y.', 'Wood, Kristin L.', 'Busch-Vishniac, Ilene J.']

2018-11-08T15:03:25Z

1995

Mechanical Engineering

doi:10.15781/T2RB6WN2V

http://hdl.handle.net/2152/69881

eng

1995 International Solid Freeform Fabrication Symposium

Open

['SLS', 'Modeling and Simulation', 'iron-galvanometer']

Modeling of Dynamic Effects Caused by the Beam Delivery System in Selective Laser Sintering

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c55470b8-799f-4ff3-9568-4ef56523a11f/download

null

In this work, the machine dynamic response in Selective Laser Sintering is investigated with the purpose of determining the causes of scanning errors. Machine subcomponents are first investigated to determine their potential effects on the laser beam positional accuracy. The dynamics of the laser beam delivery system are identified as the major contributor to deviations in the laser beam position. The moving-iron galvanometer scanner used in SLS machines is then modeled, with the ultimate goal of understanding how its various components and parameters affect part scanning accuracy. This work should provide a better understanding of the dynamics of the laser beam delivery system and give insight on machine parameters that result in better part accuracy.

null

['Kim, Dong Sung', 'Suriboot, Jakkrit', 'Grunlan, Melissa', 'Tai, Bruce L.']

2021-11-04T15:01:10Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89979

eng

2017 International Solid Freeform Fabrication Symposium

Open

['additive manufacturing', 'silicone 3D printing', 'low one-photon polymerization']

Modeling of Low One-Photon Polymerization for 3D Printing of UV-Curable Silicones

Conference paper

https://repositories.lib.utexas.edu//bitstreams/293a0e67-a471-487e-8347-ecb221100021/download

University of Texas at Austin

Low-one photon polymerization (LOPP) enables an in-liquid curing to suspend a soft silicone object in the vat without mechanical disturbance. LOPP requires a low-absorbance wavelength and a great gradient light beam to achieve the desired curing. To further control the process for 3D printing, this research aims to model LOPP behaviors of a custom-made UV-curable silicone system based on Gaussian beam and Beer-Lambert law. A methyl acrylate-based silicone was specifically formulated to pair with a 375 nm UV light and high numerical aperture lens in this work. The silicone was established with critical exposure and penetration depth by a modified “windowpane” test. The comparison results between the model and LOPP tests showed a consistent trend of polymerization. This model suggested a large penetration depth and smaller critical exposure to achieve an ideal LOPP-based printing.

null

['Wu, Zhanping', 'Ogale, Amod A.', 'Ahzi, Said', 'Paul, Frank W.', 'Hunt, Elaine']

2018-12-07T17:15:46Z

1997

Mechanical Engineering

doi:10.15781/T23776F87

http://hdl.handle.net/2152/71453

eng

1997 International Solid Freeform Fabrication Symposium

Open

['rapid prototypes', 'manufacturing']

Modeling of Mechanical Behavior of SLA Parts

Conference paper

https://repositories.lib.utexas.edu//bitstreams/90553b9f-a9bf-4105-8bc9-f67fcdfc0ecb/download

null

In recent years, important efforts have been focused on producing functional parts using Stereolithography Apparatus ( SLA ). One of the applications is the development of rapid polymer tooling such as dies for injection molding. For these applications, optimal thermal as well as mechanical properties are of significance. In this paper, the mechanical behavior of the cured resin SL5170 is discussed by use of an elastic-viscoplastic material model. Uniaxial compression tests at different deformation rates are conducted. The stress-strain curves of these tests are predicted by the model, and comparisons of these results with experiments show good agreement.

null

['Vail, N.K.', 'Barlow, J.W.']

2018-10-03T18:35:54Z

1994

Mechanical Engineering

doi:10.15781/T2930PD6F

http://hdl.handle.net/2152/68675

eng

1994 International Solid Freeform Fabrication Symposium

Open

['SLS', 'green composites', 'polymer binder materials']

Modeling of Polymer Degradation in SLS

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7df24bd2-6331-4d61-a601-06c18f1ed63e/download

null

A simple computer model has been developed to predict the thermal degradation of polymer binders used in the fabrication of composite green shapes from high temperature ceramic materials. Decomposition rate kinetics of the polymer materials were determined and incorporated into the model. The polymer degradation occurring in three separate powder systems was determined as a function of applied laser energy. Agreement between model results and experimental data is quite good. (Key Words: Polymer, Degradation, Selective Laser Sintering, Composites).

null

['Flood, Aaron', 'Liou, Frank']

2021-10-21T16:59:26Z

2015

Mechanical Engineering

null

https://hdl.handle.net/2152/89406

eng

2015 International Solid Freeform Fabrication Symposium

Open

['powder bed processing', 'powder bed', 'Discrete Element Method', 'Geometric Method']

Modeling of Powder Bed Processing – A Review

Conference paper

https://repositories.lib.utexas.edu//bitstreams/38c35c84-2e49-4d2f-9e99-d9179de341a8/download

University of Texas at Austin

Many models have been developed to model powder beds and these methods can be implemented to model a powder bed for Selective Laser Sintering, Selective Laser Melting and any other technique of additive manufacturing which uses powder beds. Two of the main systems are the Discrete Element Method (DEM) and the Geometric Method. The purpose of this paper is to analyze each of the methods. It will first highlight how each of the models creates the powder bed. The next aspect reviewed is the computational time and its causes. And lastly, each of the methods will be examined for their accuracy as shown from various experiments that have been reported in literature. In addition to these methods, there are several others that have been proposed that will also be studied and compared to highlight the strengths and weaknesses of each.

null

['Mendez, Patricio', 'Brown, Stuart']

2018-10-03T16:03:32Z

1994

Mechanical Engineering

doi:10.15781/T2GQ6RM7G

http://hdl.handle.net/2152/68658

eng

1994 International Solid Freeform Fabrication Symposium

Open

['selective laser sintering', 'model', 'thermal']

Modeling of Selected SFF Process Limits

Conference paper

https://repositories.lib.utexas.edu//bitstreams/74717653-2585-4b16-8ba9-5a3d5d75242c/download

null

An analytical model of the thermal field for one scan line during SLS is developed. Quantitative relationships between net heat input and beam velocity are stated for sintering at a given distance from the center of the beam and for the case of maximum surface temperature. For the maximum surface temperature, two extreme cases have been analyzed: pure conduction heat transport, and highly convective molten consolidation. It is suggested that a highly convective process allows significantly higher net heat input than pure conduction. It is found that for certain conditions, the relationship between net heat input and beam velocity is independent of the thermal conductivity of the material. Key Words: model, melting, selective laser sintering, thermal, process window.

null

['Jacquot, Y.', 'Zong, S.', 'Marcus, H.L.']

2018-04-10T17:25:23Z

1990

Mechanical Engineering

doi:10.15781/T2ZS2KW7H

http://hdl.handle.net/2152/64240

eng

1990 International Solid Freeform Fabrication Symposium

Open

['Center for Materials Science and Engineering', 'SFF', 'SALD', 'selective area laser deposition']

Modeling of Selective Area Laser Deposition for Solid Freeform fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/a8abd8cf-12f7-4376-b2cd-597af851c2ed/download

null

The results of a theoretical study of the selective area laser deposition process used for Solid Freeform Fabrication (SFF) from gas phase is presented. We show how the deposition profile of carbon deposited via pyrolytic laser chemical vapor deposition using acetylene as the source gas can be computed by taking into account heat transfer, reaction, and mass transfer processes inside the reactor. The two dimensional representation of the related experimental variables are used to describe the substrate temperature, carbon deposit, and acetylene concentration in the process. The parameters describing these processes are estimated.

null

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

2019-10-18T15:42:26Z

2001

Mechanical Engineering

null

['https://hdl.handle.net/2152/76243', 'http://dx.doi.org/10.26153/tsw/3332']

eng

2001 International Solid Freeform Fabrication Symposium

Open

Deposition

Modeling of Selective Area Laser Deposition Vapor Infiltration (SALDVI) of Silicon Carbide

Conference paper

https://repositories.lib.utexas.edu//bitstreams/67e87486-9a13-40ac-a04a-bb476f6dae4b/download

null

Selective Area Laser Deposition Vapor Infiltration (SALDVI) is a developing solid freeform fabrication (SFF) technique in which porous layers of powder are densified by infiltrating the pore spaces with solid material deposited from a gas precursor during laser heating. A 3D finite element model was developed that simulates SALDVI of silicon carbide. The model predicts the laser input power and the distribution of vapor deposited SiC within the powder bed as well as on the surface of the powder bed (SALD). The model considers a moving Gaussian distribution laser beam, temperatureand porous-dependent thermal conductivity, specific heat and temperature-dependent deposition rate. Furthermore, the model also includes closed-loop control of the laser power to achieve a desired target processing temperature on the top surface of the power bed. The simulation results agree fairly well with experimental data for simple geometries and offer guidelines for further experimental studies of the SALDVI process.

null

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

2020-02-14T16:23:16Z

2004

Mechanical Engineering

null

['https://hdl.handle.net/2152/79993', 'http://dx.doi.org/10.26153/tsw/7018']

eng

2004 International Solid Freeform Fabrication Symposium

Open

direct laser deposition process

Modeling of the Metal Powder Flow with Carrier Gas in Coaxial Nozzle for Direct Laser Deposition Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4ed514ee-746b-4cb6-add4-3f7cee8da850/download

null

In direct laser deposition process, metal powder is directly fed with carrier gas through the coaxial nozzle into the melt pool created by the laser to form the solid parts. Many operational parameters of the process depend on the characteristic of the powder stream structure below the exit of the coaxial nozzle. In this paper, a computational approach is developed for the simulation of the gas-particle flow in the coaxial nozzle. By taking into account the nozzle geometry and operating parameters, such as width and inclination angle of powder passage and carrier gas velocity, the developed computational code allows the simulation, optimization and control of the delivery of the metal powders.

null

['Bai, X.W.', 'Zhang, H.O.', 'Wang, G.I.']

2021-10-18T21:29:29Z

2014

Mechanical Engineering

null

https://hdl.handle.net/2152/89252

eng

2014 International Solid Freeform Fabrication Symposium

Open

['induction heating', 'weld-based additive manufacturing', 'residual stresses']

Modeling on the Moving Induction Heating Used in Weld-Based Additive Manufacturing

Conference paper

https://repositories.lib.utexas.edu//bitstreams/e93b56a8-0811-4269-be4b-252a69ed6cc1/download

University of Texas at Austin

This paper numerically investigates the application induction heating in weld-based additive manufacturing to reduce residual stresses. To avoid time-consuming transient electromagnetic calculation, the induction heat is assumed to be constant in the arc coordinate. Thermo-electromagnetic coupling analysis is performed only at a typical time to obtain the representative distribution of induction heat, which is then transferred to the thermal analysis of multilayer deposition as a secondary heat source. Furthermore, the effects of real-time induction preheating and postheating on residual stress state are analyzed in comparative simulations. The results show that both induction preheating and postheating lead to more homogeneous heat input and lower residual stresses compared with the case without induction heating.

null

['Thomas, J. P.', 'Rodriguez, J. F.']

2019-06-13T14:07:44Z

2000

Mechanical Engineering

null

['https://hdl.handle.net/2152/74942', 'http://dx.doi.org/10.26153/tsw/2054']

eng

2000 International Solid Freeform Fabrication Symposium

Open

['Fused-Deposition (FD)', 'FD-ABS']

Modeling the Fracture Strength between Fused-Deposition Extruded Roads 16

Conference paper

https://repositories.lib.utexas.edu//bitstreams/bc3e3f26-0cf5-4fc6-8919-29b0f1d455a1/download

null

The fracture strength developed between Fused-Deposition extruded roads is modeled in terms of the wetting and thermally-driven diffusion bonding processes. Thermal histories at the road-to-road interface are obtained from a heat transfer analysis and used to develop model predictions based on reptation theory for the interdiffusion of long-chain polymer molecules. Fracture toughness data on FD-ABS plastic specimens is used to quantify the model. The results show that most of the fracture strength develops during the surface wetting stage of bonding and that slower cooling rates during solidification promote stronger bonding between the roads.

null

Soylemez, E.

2021-11-11T16:41:00Z

2018

Mechanical Engineering

null

['https://hdl.handle.net/2152/90242', 'http://dx.doi.org/10.26153/tsw/17163']

eng

2018 International Solid Freeform Fabrication Symposium

Open

['finite element analysis', 'selective laser melting', 'keyhole', 'process map']

Modeling the Melt Pool of the Laser Sintered Ti6Al4V Layers with Goldak's Double-Ellipsoidal Heat Source

Conference paper

https://repositories.lib.utexas.edu//bitstreams/4eb85183-6308-41b1-a77a-a7d09e6c1487/download

University of Texas at Austin

Selective laser melting process has been widely studied to elucidate the effects of process parameters (laser speed, laser power, scan strategy, hatch distance, layer thickness, etc.) on the manufactured parts. Experimental and numerical modeling studies have been investigating the melt pool shapes of the laser sintered layers to correlate the melt pool geometry with the part quality. Although modeling results agree with the experiments, the melt pool cross-section may form key holing rather than semi-circular shape due to Marangoni effect, recoil pressure, and sudden evaporation for some process parameters combinations. To accurately model the melt pool depth, this study proposes a finite element analysis (FEA) model that simulates the laser source as the Goldak’s double-ellipsoidal heat power density model. Single bead experiments of Ti6Al4V were conducted within the processing range of laser sintering system with the 400 W laser, and these experimental results allowed to verify simulated FEA results.

null

['Hoskins, Dylan', 'Kim, Seokpum', 'Hassen, Ahmed', 'Lindahl, John', 'Kunc, Vlastimil', 'Duty, Chad']

2021-11-18T17:02:23Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90429', 'http://dx.doi.org/10.26153/tsw/17350']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['coefficient of thermal expansion', 'CTE', 'non-homogenized approach', 'large area extrusion deposition additive manufacturing', 'LAEDAM']

Modeling Thermal Expansion of a Large Area Extrusion Deposition Additively Manufactured Parts Using a Non-Homogenized Approach

Conference paper

https://repositories.lib.utexas.edu//bitstreams/7518b6b0-45f7-486b-806c-0c86871b255b/download

University of Texas at Austin

Interest in the use of large area extrusion deposition additive manufacturing (LAEDAM) to create tools for creation of composites is on the rise, due to its ability to create complex shapes rapidly. To ensure the parts created from the tool meet geometric standards, it is important to understand the thermal expansion of the printed part. Which is a challenge as LAEDAM imparts a non-uniform fiber orientation to the deposited material. A non-uniform fiber orientation in the deposited material creates a non-homogeneous cross section at a given position. Due to this heterogeneity, the coefficient of thermal expansion (CTE) also varies according to the position in the cross section. Previous modelling attempts of LAEDAM parts have employed a homogenized approach. This work experimentally characterizes CTE variations across the cross section of a bead using thermomechanical analysis and uses this as a non-homogenized input at the bead level for a finite element model. Predictions from this finite element model are then be compared to strain maps measured using 2-D digital image correlation of large-scale printed parts (127 mm cubes).

null

['Li, Mingyang', 'Landers, Robert G.', 'Leu, Ming C.']

2021-10-06T21:21:53Z

8/15/12

Mechanical Engineering

null

['https://hdl.handle.net/2152/88448', 'http://dx.doi.org/10.26153/tsw/15385']

eng

2012 International Solid Freeform Fabrication Symposium

Open

['ceramic paste solidifcation', 'numerical simulations']

Modeling, Analysis and Simulation of Paste Freezing in Freeze-form Extrusion Fabrication

Conference paper

https://repositories.lib.utexas.edu//bitstreams/c9fad069-d680-4248-b2de-7eaa0a05c1cf/download

University of Texas at Austin

During the freeze-form extrusion fabrication process for aqueous-based pastes, the sub-zero temperature environment aids the part in maintaining its shape by freezing the water present in the paste. The paste freezes very quickly when deposited on a substrate in a freezing environment. However, as the part’s height increases, the freezing time increases as the heat conduction rate to the substrate decreases. The freezing time can exceed the time required to extrude one layer of paste due to water’s high latent heat, thus leaving the extruded paste in its semi-liquid state and causing the part to deform or even collapse. Therefore, dwell time is needed between layers, which may substantially increase the build time of the part. In this paper, the effects of the paste material, paste solids loading, convection coefficient, initial paste temperature, ambient temperature, total time between layers, and layer thickness on the freezing time of paste are investigated. The paste temperature and paste freezing time are computed for various process parameters via numerical simulation using the commercial code Fluent.

null

['Šeta, Berin', 'Mollah, Md. Tusher', 'Kumar, Vipin', 'Pokkalla, Deepak Kumar', 'Kim, Seokpum', 'Hassen, Ahmed Arabi', 'Spangenberg, Jon']

2023-01-26T21:37:50Z

2022

Mechanical Engineering

null

['https://hdl.handle.net/2152/117324', 'http://dx.doi.org/10.26153/tsw/44205']

eng

2022 International Solid Freeform Fabrication Symposium

Open

molding

Modelling Fiber Orientation during Additive Manufacturing-Compression Molding Processes

Conference paper

https://repositories.lib.utexas.edu//bitstreams/44604e13-e0f8-45ff-be64-edc945b3f225/download

null

The production of high-performance thermoplastic composites reinforced with short carbon fibers can be achieved by a novel “additive manufacturing-compression molding” technique. An advantage of such a combination is two-fold: controlled fiber orientation in additive manufacturing and less void content by compression molding. In this study, a computational fluid dynamics model has been developed to predict the behavior of printed layers during fiber-reinforced thermoplastic extrusion and subsequent compression molding. The fiber orientation was modelled with the simple quadratic closure model. The interaction between the fibers was included using a rotary diffusion coefficient that becomes significant in concentrated regimes. Finally, the second rank orientation tensor was coupled with the momentum equation as an anisotropic part of the stress term. The effect of different fiber orientation within printed layers was investigated to determine the favorable printing scenarios in the strands that undergo compression molding afterwards. The developed numerical model enables design of high-performance composites with tunable mechanical properties.

null

['Wu, Yan', 'Yang, Li']

2021-11-30T21:57:40Z

2019

Mechanical Engineering

null

['https://hdl.handle.net/2152/90563', 'http://dx.doi.org/10.26153/tsw/17482']

eng

2019 International Solid Freeform Fabrication Symposium

Open

['tensile fracture', 'cellular structures', 'crack propagation', 'size effect']

Modelling for the Tensile Fracture Characteristic of Cellular Structures under Tensile Load with Size Effect

Conference paper

https://repositories.lib.utexas.edu//bitstreams/60c3a425-180a-46c5-bb3c-10d43c019146/download

University of Texas at Austin

In the unit cell-based design of cellular structures, an important issue is the effect of the cellular pattern size (i.e. the number of unit cell numbers along different orientations) on their mechanical properties. Among these properties, the fracture properties are of great importance for a broad range of applications but have been rarely investigated. In this work the size effects on the fracture characteristic (including failure initiation, crack propagation and failure patterns) of the BCC, octet-truss, auxetic and octahedral structures under tensile loadings were analyzed based analytical models. It was found that for the fracture of the cellular structures there exist significant coupling effects between the unit cell topology and the cellular pattern size. The results also clearly suggested the importance of dedicating more design attentions to the boundaries of the cellular structures during their fracture designs. This study provides additional insights into the design considerations for the fracture properties of the cellular structures.

null

['Dibua, Obehi G.', 'Yuksel, Anil', 'Roy, Nilabh K.', 'Foong, Chee S.', 'Cullinan, Michael']

2021-11-03T20:33:23Z

2017

Mechanical Engineering

null

https://hdl.handle.net/2152/89925

eng

2017 International Solid Freeform Fabrication Symposium

Open

['nanoparticle diffusion', 'nanoparticle sintering', 'modelling', 'microscale selective laser sintering', 'μ-SLS']

Modelling Nanoparticle Sintering in a Microscale Selective Laser Sintering Process

Conference paper

https://repositories.lib.utexas.edu//bitstreams/5a530b4b-0f73-4289-afb8-2e540948faf4/download

University of Texas at Austin

An important aspect of making microscale selective laser sintering (μ-SLS) a viable commercial process is having the ability to predict the structural properties of sintered parts. This prediction is made possible through accurate models of the sintering process. The majority of SLS models simulate sintering as a melting process which is accurate for microparticles. However, for nanoscale particles the sintering process becomes dominated by grain boundary and surface diffusion between particles. Though there are currently research efforts on modeling the sintering behavior between nanoparticles, these efforts revolve around simulations with only a few particles. This paper presents an approach to modelling diffusion between nanoparticles in full sized beds made up of hundreds of particles. The simulations presented in this paper are done using a phase field modeling (PFM) approach that can be used to predict properties such as the porosity, shrinkage and relative density of sintered parts, which can then be compared against experimental data.

null