Engineering Commons^™

Modeling Residual Stress Development In Hybrid Processing By Additive Manufacturing And Laser Shock Peening, Guru Charan Reddy Madireddy

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

The term “hybrid” has been widely applied to many areas of manufacturing. Naturally, that term has found a home in additive manufacturing as well. Hybrid additive manufacturing or hybrid-AM has been used to describe multi-material printing, combined machines (e.g., deposition printing and milling machine center), and combined processes (e.g., printing and interlayer laser re-melting). The capabilities afforded by hybrid-AM are rewriting the design rules for materials and adding a new dimension in the design for additive manufacturing paradigm. This work focuses on hybrid-AM processes, which are defined as the use of additive manufacturing (AM) with one …

Repeatability Case Study Of The 3d Printer In The School Of Engineering And Applied Science Lab, Naif Faleh S. Albaiji

Masters Theses & Specialist Projects

3DP (three-dimensional printing) technologies have become more than just a tool to help companies with prototyping and designing in the pre-production stage. Some firms have already implemented 3DP technology to produce parts and end-use products. However, there are several challenges and barriers that this technology must overcome to replace traditional manufacturing methods. One of the most significant obstacles associated with 3D printing is its low level of accuracy in variable repeatability when it comes to making separate batches of the same product. There are several arguable reasons behind this variation. Some of the factors that can influence repeatability are the …

Additive Manufacturing Of Transparent Fused Quartz, Junjie Luo, John M. Hostetler, Luke Gilbert, Jonathan T. Goldstein, Augustine M. Urbas, Douglas A. Bristow, Robert G. Landers, Edward C. Kinzel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper investigates a filament-fed process for additive manufacturing (AM) of fused quartz. Glasses such as fused quartz have significant scientific and engineering applications, which include optics, communications, electronics, and hermetic seals. AM has several attractive benefits such as increased design freedom, faster prototyping, and lower processing costs for small production volumes. However, current research into glass AM has focused primarily on nonoptical applications. Fused quartz is studied here because of its desirability for use in high-quality optics due to its high transmissivity and thermal stability. Fused quartz filaments are fed into a CO₂ laser-generated molten region, smoothly depositing …

Direct Metal Laser-Sintered Stainless Steel: Comparison Of Microstructure And Hardness Between Different Planes, M. Ghasri-Khouzani, H. Peng, R. Attardo, P. Ostiguy, J. Neidig, R. Billo, D. Hoelzle, M. R. Shankar

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Microstructural analysis and micro-hardness measurements were performed on different planes of 316L stainless steel fabricated by direct metal laser sintering (DMLS) technique. A fine cellular network was observed within the steel microstructure, where morphology of most cells changed from columnar on XZ-plane (vertical section) to equiaxed on XY-plane (horizontal section). Correspondingly, morphology of most grains was found to alter from columnar for the XZ-plane to equiaxed in the case of the XY-plane. Moreover, X-ray diffraction (XRD) analysis revealed a fully austenitic structure for both the planes. The average micro-hardness value for the XZ-plane and XY-plane was insignificantly (≈ 3%) different, …

Case Study: Cooling Channels For Material Testing Applications Using Laser Powder Bed Fusion, Benjamin M. Doane, Ryan P. O'Hara, K. Liu, Carl R. Hartsfield

Faculty Publications

Additive Manufacturing continues to gain a reputation as a key technology that will have a major impact on all aspects of mechanical engineering. The United States Air Force’s (USAF) Air Force Institute of Technology (AFIT), based in Dayton, Ohio, has expanded its AM-focused education and R&D capabilities with the purchase of a Laser Powder Bed Fusion system from Germany’s Concept Laser.

Effects Of Manufacturing Process Variables On Ultrasonic Testing In Electron Beam Melted Ti-6al-4v, Andrew D. Durkee

Theses and Dissertations

Further research on validating additive manufacturing production quality is required before the realization of direct print-to-fly application of critical components. This research examines the response of ultrasonic testing as a function of various manufacturing variables in electron beam melted samples of Ti-6Al-4V. Four dimensionally identical blocks with 6 spherical voids at varying depths were manufactured using different combinations of stock powder, edge treatments, and void melting. Scans were completed on two sides of each specimen with the transducer focused on the mid-plane. Additionally, one specimen was scanned 6 times, with the focal plane adjusted for each scan to match the …

Design And Testing Of An Additively Manufactured Cubesat Structural Bus, Karson A. Roberts

Theses and Dissertations

Recent innovations in additive manufacturing and design capabilities have opened the door for more opportunities to integrate multiple functions into a structural de- sign. Specifically, 3D printing through advanced laser powder bed fusion of metal powder allows for the development and integration of advanced structures that were previously unachievable. The demonstration of these techniques on a small satellite results in a structural bus consisting of various external and internal features, increasing its functionality and capabilities beyond simply providing structural support. 3D printing a multi-functional CubeSat bus with these integrated features such as internal lattices and wiring tabs demonstrates a new …

Selective Laser Melting Of Ni-Rich Niti: Selection Of Process Parameters And The Superelastic Response, Narges Shayesteh Moghaddam, Soheil Saedi, Amirhesam Amerinatanzi, Ehsan Saghaian, Ahmadreza Jahadakbar, Haluk E. Karaca, Mohammad Elahinia

Mechanical Engineering Faculty Publications

Material and mechanical properties of NiTi shape memory alloys strongly depend on the fabrication process parameters and the resulting microstructure. In selective laser melting, the combination of parameters such as laser power, scanning speed, and hatch spacing determine the microstructural defects, grain size and texture. Therefore, processing parameters can be adjusted to tailor the microstructure and mechanical response of the alloy. In this work, NiTi samples were fabricated using Ni_50.8Ti (at.%) powder via SLM PXM by Phenix/3D Systems and the effects of processing parameters were systematically studied. The relationship between the processing parameters and superelastic properties were investigated …

Development Of A Resilient 3-D Printer For Humanitarian Crisis Response, Benjamin L. Savonen, Tobias Mahan, Maxwell W. Curtis, Jared W. Schreier, John K. Greshonen, Joshua M. Pearce

Department of Materials Science and Engineering Publications

Rapid manufacturing using 3-D printing is a potential solution to some of the most pressing issues for humanitarian logistics. In this paper, findings are reported from a study that involved development of a new type of 3-D printer. In particular, a novel 3-D printer that is designed specifically for reliable rapid manufacturing at the sites of humanitarian crises. First, required capabilities are developed with design elements of a humanitarian 3-D printer, which include, (1) fused filament fabrication, (2) open source self-replicating rapid prototyper design, (3) modular, (4) separate frame, (5) protected electronics, (6) on-board computing, (7) flexible power supply, and …

Analysis Of Additively Manufactured Injectors For Rotating Detonation Engines, Michael C. Waters

Theses and Dissertations

This research represents an experimental and computational analysis of additively manufactured injectors for Rotating Detonation Engines (RDEs) for use in rocket propulsion. This research was based on the manufacture and testing of existing injector element designs using additive techniques. The designs were modeled from geometries gathered from Sutton and Biblarz Elements of Rocket Propulsion [23]. The goal of this research was to characterize the viscous losses of each design based on the discharge coefficient. The designs were computationally simulated to gain insight to the flow characteristics using multiple sets of conditions for surface roughness and inlet pressure. The results were …

Bio-Mimetic Design With 3d Printable Composites, Ramya Mitra Patnam Damodaram

Electronic Theses and Dissertations

Weight and stiffness are key factors in the advancement of materials and parts for use in numerous industries. Lightweight cellular structures are broadly utilized for this reason. However, these structures must satisfy several key constraints: they should be light yet structurally safe, sustainable in different loading conditions, resource efficient and easy to maintain. Bio-inspired materials/structures which results in desirable material features are a significant inspiration for engineered cellular structures. Cellular structures can be designed to have multifunctional properties along with lightweight characteristics. Currently, these structures with high strength to weight ratio are widely applied in many fields such as automotive, …

Impact Of Vapor Polishing On Surface Quality And Mechanical Properties Of Extruded Abs, Clayton Neff, Matthew Trapuzzano, Nathan B. Crane

Faculty Publications

Purpose — Additive manufacturing (AM) is readily capable of producing models and prototypes of complex geometry and is advancing in creating functional parts. However, AM processes typically underperform traditional manufacturing methods in mechanical properties, surface roughness, and hermeticity. Solvent vapor treatments (vapor polishing) are commonly used to improve surface quality in thermoplastic parts, but the results are poorly characterized.

Design/methodology/approach — This work quantifies the surface roughness change and also evaluates the effect on hermeticity and mechanical property impacts for “as-printed” and acetone vapor-polished ABS tensile specimens of 1, 2, and 4 mm thicknesses produced by material extrusion (FDM).

Findings …

Additive Manufacturing Of Multi-Functional Nanocomposites For Sensor And Energy Storage Devices, Hoejin Kim

Open Access Theses & Dissertations

The goal of this research is to develop novel 3D printing process and design nanocomposites for piezoelectric and dielectric devices using fused deposition modeling (FDM) and stereolithography (SL) 3D printing techniques for use in sensor and energy storage applications. Techniques for electric and corona assisted in-situ poling during 3D printing were developed to improve the piezoelectric property and ease of manufacture. Poly(vinylidene fluoride) (PVDF) and barium titanate (BaTiO3, BT) are well-known for their high piezo- and dielectric constants among polymers and ceramics, while multi-walled carbon nanotubes (CNTs) were introduced to improve efficiency of stress reinforcement and conductivity for charge carriers …

Development And Characterization Of Novel Materials For The Advancement Of Additive Manufacturing By Material Extrusion 3d Printing, Jose Gilberto Siqueiros

Open Access Theses & Dissertations

The development of additive manufacturing technologies has been under the spotlight from the past decade due to its enormous potential to disrupt current manufacturing processes. Material extrusion 3D printing (ME3DP) is the most common type of additive manufacturing technology as it experienced an exponential growth after the expiration of the fused deposition modeling patent filed in 1989 by Scott Crump. The large interest behind this technology is generated from the capacity to create complex shapes, rapid prototyping, relatively ease of use, low cost, and high accessibility. The gradual evolution of material extrusion 3D printing calls to become a technology ordinarily …

Experimental Laser Powder Bed Fusion System For Difficult To Process Metallic Materials, Syed Zia Uddin

Open Access Theses & Dissertations

The focus of this research was twofold, such as development of defect free fabrication parameters for laser powder bed fusion (LPBF) processing of crack prone or difficult to process metallic materials, and study of the temperature dependence of emissivity for some commonly used metal alloy powders in LPBF process. The later objective extends to the implementation of multiwavelength (MW) pyrometer technology for in situ true surface temperature measurement in LPBF process. LPBF is an additive manufacturing (AM) process capable of layer-by-layer manufacturing by successive laser melting of each layer according to CAD data. AM manufacturing has the inherent advantages of …

Investigation Of Scanning Kelvin Probe Techniques, Nicholas D'Angelo Jr., Hongbo Cong

Williams Honors College, Honors Research Projects

The original scope of this work was to advance the understanding of corrosion properties of additively manufactured (AM) materials by correlating microstructural defects in AM materials to the material conventional counterparts utilizing a scanning kelvin probe [Ametek VeraSCAN Electrochemical System]. However, upon the initiation of project research, it was observed that the system was not operational due to unknown hardware and software problems. The evolved scope of this work was to reconcile the operational issues and develop a repair and mitigation plan. After extensive troubleshooting, it was determined that the software was not properly configured, and the electrometer had permanently …

Layer-To-Layer Physical Characteristics And Compression Behavior Of 3d Printed Acrylonitrile Butadiene Styrene Metastructures Fabricated Using Different Process Parameters, Sivani Patibandla

Browse all Theses and Dissertations

Three-dimensional (3D) printing, a subset of additive manufacturing, is currently being explored heavily for actual part fabrication due to its ability to create complex objects with intricate internal features. There are several 3D printing technologies; however, the extrusion-based technology such as fused deposition modeling (FDM) is the widely used one owing to its low cost. The FDM method can be used to fabricate parts with different fill densities, fill patterns, and process parameters such as extruder temperature and print speed. In this research, influence of process parameters such as extruder temperature and speed on the physical characteristics such as the …

Formulation Of Uv Curable Resins Utilized In Vat Photo Polymerization For The Additive Manufacturing Of Gun Propulsion Charge In 3d Printers, David T. Bird

Theses

Formulating resins for Additive Manufacturing (AM), utilizing UV laser stereolithography, is a new technique that makes it possible for the fabrication of complex geometries with high dimensional resolution. This layer by layer photopolymerization approach spans various industrial sectors from adhesives, inks and optical fibers to nanotechnology and biomaterials. UV curable resins such as epoxides, vinyl ethers and other acrylates are important monomers that offer effective mediums for energetic materials, and the potential exists to develop environmentally friendly formulations with suspended energetic materials at various solids loading levels.

Developing techniques for UV curing formulations of highly loaded energetic suspensions is a …

Towards The Fabrication Of Bioresorbable Constructs With Customized Properties Using Additive Manufacturing, Prashanth Ravi

Mechanical and Aerospace Engineering Dissertations - Archive

Additive Manufacturing (AM) has been employed to fabricate medical constructs for over two decades. This dissertation investigates the effects of AM process parameters on raster level geometric features and structural properties of bioresorbable constructs. The development of an open architecture custom multi-process 3D printer employed for fabricating bioscaffolds and test structures is discussed. Bioresorbable polymers including a newly synthesized radiopaque polymer, poly (glycerol sebacate fumarate) gadodiamide (Rylar) and medical grade poly-L-lactic acid (PLLA) were investigated. In the first part, the effects of process parameters on raster geometry were investigated to aid in the fabrication of structures with improved geometric features …

A Design Methodology For Continuous Fiber Additive Manufacturing Using Advanced Computer Aided Engineering Techniques, Nicholas Venter

Mechanical and Aerospace Engineering Theses - Archive

A design methodology for Continuous Carbon Fiber Additive Manufacturing (CCFAM) developed using Computer Aided Engineering (CAE) techniques takes advantage of both the mechanical strength of composite materials and the Fused Filament Fabrication (FFF) method. By performing topology optimization and Finite Element Analysis (FEA) on a load-bearing part, engineers can design much lighter optimized parts that are just as strong as those produced using FFF. This weight reduction is achieved by relying on the mechanical strength of continuous carbon fibers printed alongside a traditional thermoplastic matrix. The FFF additive manufacturing method enables the production of complex shapes, which can match the …

Direct Digital Manufacturing Of Multi-Layer Wideband Ku-Band Patch Antennas, Merve Kacar

USF Tampa Graduate Theses and Dissertations

Design and performance of fully-printed Ku-band aperture coupled patch antennas fabricated by a direct digital manufacturing (DDM) approach that integrates fused deposition modeling (FDM) of acrylonitrile butadiene styrene (ABS) thermoplastic with in-situ micro-dispensing of conductive silver paste (CB028) are reported. Microstrip line characterizations are performed and demonstrate that misalignment of ABS substrate deposition direction with microstrip line micro-dispensing direction can degrade the effective conductivity up to 60% within the Ku-band, and must be taken into consideration in antenna array feed network designs. Specically, over 125 µm thick ABS substrate, RF loss of 0.052 dB/mm is obtained at 18 GHz, demonstrating …

Experimental Measurement Of Residual Stress And Distortion In Additively Manufactured Stainless Steel Components With Various Dimensions, M. Ghasri-Khouzani, H. Peng, R. Rogge, R. Attardo, P. Ostiguy, J. Neidig, R. Billo, D. Hoelzle, M. R. Shankar

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Disk-shaped 316L stainless steel parts with various diameters and heights were additively manufactured using a direct metal laser sintering (DMLS) technique. Neutron diffraction was used to profile the residual stresses in the samples before and after removal of the build plate and support structures. Moreover, distortion level of the parts before and after the removal was quantified using a coordinate measuring machine (CMM). Large tensile in-plane stresses (up to ≈ 400 MPa) were measured near the as-built disk top surfaces, where the stress magnitude decreased from the disk center to the edges. The stress gradient was steeper for the disks …

Distributed Manufacturing Of Flexible Products: Technical Feasibility And Economic Viability, Aubrey Woern, Joshua M. Pearce

Department of Materials Science and Engineering Publications

Distributed manufacturing even at the household level is now well established with the combined use of open source designs and self-replicating rapid prototyper (RepRap) 3-D printers. Previous work has shown substantial economic consumer benefits for producing their own polymer products. Now flexible filaments are available at roughly 3-times the cost of more conventional 3-D printing materials. To provide some insight into the potential for flexible filament to be both technically feasible and economically viable for distributed digital manufacturing at the consumer level this study investigates 20 common flexible household products. The 3-D printed products were quantified by print time, electrical …

Note On The Rate And Energy Efficiency Limits For Additive Manufacturing, Timothy Gutowski, Sheng Jiang, Daniel Cooper, Gero Corman, Michael Hausmann, Jan-Anders Manson, Timo Schudeleit, Konrad Wegener, Matias Sabelle, Jorge Ramos-Grez, Dusan P. Sekulic

Mechanical Engineering Faculty Publications

We review the process rates and energy intensities of various additive processing technologies and focus on recent progress in improving these metrics for laser powder bed fusion processing of metals, and filament and pellet extrusion processing of polymers and composites. Over the last decade, observed progress in raw build rates has been quite substantial, with laser metal processes improving by about 1 order of magnitude, and polymer extrusion processes by more than 2 orders of magnitude. We develop simple heat transfer models that explain these improvements, point to other possible strategies for improvement, and highlight rate limits. We observe a …

3d Printing Of 316l Stainless Steel And Its Effect On Microstructure And Mechanical Properties, Rawn Penn

Graduate Theses & Non-Theses

Laser powder bed fusion or 3D printing is a potential candidate for net shape forming and manufacturing complex shapes. Understanding of how various parameters affect build quality is necessary. Specimens were made from 316L stainless steel at 0°, 30°, 60°, and 90° angles measured from the build plate. Three tensile and four fatigue specimens at each angle were produced. Fracture morphology investigation was performed to determine the fracture mode of specimens at each build angle. Microstructural analysis was performed on one of each orientation. The average grain size of the samples was marginally influenced by the build angle orientation. Tensile …

Building Zr-Based Metallic Glass Part On Ti-6al-4v Substrate By Laser-Foil-Printing Additive Manufacturing, Yingqi Li, Yiyu Shen, Ming-Chuan Leu, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Through using Zr intermediate layers, Zr_52.5Ti₅Al₁₀Ni_14.6Cu_17.9 metallic glass (MG) parts are successfully built on Ti-6Al-4V substrates by laser-foil-printing (LFP) additive manufacturing technology in which MG foils are laser welded layer-by-layer onto the substrate. The printed MG part is free of porosity, cracking and crystallization; additionally, its glass transition temperature, crystallization temperature, micro-hardness, and tensile strength are very similar to the original MG material. The Zr intermediate layers are aimed at preventing direct interaction between the first layer of MG foil and the Ti substrate; otherwise, the welded MG foils would peel …

Additive Manufacturing Of High Solids Loading Hybrid Rocket Fuel Grains, Stephen P. Johnson, Michael Baier, Ibrahim E. Gunduz, Steven F. Son

The Summer Undergraduate Research Fellowship (SURF) Symposium

Hybrid rocket motors offer many of the benefits of both liquid and solid rocket systems. Like liquid engines, hybrid rocket motors are able to be throttled, can be stopped and restarted, and are safer than solid rocket motors since the fuel and oxidizer are in different physical states. Hybrid rocket motors are similar to solid motors in that they are relatively simple and have a high density-specific impulse. One of the major drawbacks of hybrid rocket motors is a slower burning rate than solid rocket motors. Complex port geometries provide greater burning surface area to compensate for lower burning rates …

Crack Healing In 304l Stainless Steel Using Additive Manufacturing And Friction Stir Processing (Fsp), Cameron Scott Gygi

Theses and Dissertations

Continuing an investigation on using FSP to heal stress corrosion cracks (SCC) in welds on nuclear reactors, this study seeks to use AM in addition to FSP to aid crack repair. Previous studies address that current repair technology on nuclear reactors involves the use of TIG welding which can allow helium atoms to aggregate and form voids at the grain boundaries. This weakens the material and renders the repair ineffective. Another previous study evaluated the effectiveness of FSP alone in repairing SCC which did have defects depending on the parameters used during FSP. This study evaluated the use of AM …

Impact Of Diy Home Manufacturing With 3d Printing On The Toy And Game Market, Emily Peterson, Joshua M. Pearce

Department of Materials Science and Engineering Publications

The 2020 toy and game market is projected to be US$135 billion. To determine if 3D printing could affect these markets if consumers offset purchases by 3D printing free designs, this study investigates the 100 most popular downloaded designs at MyMiniFactory in a month. Savings are quantified for using a Lulzbot Mini 3D printer and three filament types: commercial filament, pellet-extruded filament, and post-consumer waste converted to filament with a recyclebot. Case studies probed the quality of: (1) six common complex toys; (2) Lego blocks; and (3) the customizability of open source board games. All filaments analyzed saved the user …

High Performance Digitally Manufactured Microwave And Millimeter-Wave Circuits And Antennas, Eduardo A. Rojas

USF Tampa Graduate Theses and Dissertations

The potential of Additive Manufacturing (AM) for microwave and mm-wave applications is increasingly being revealed thanks to recent advancements in research. AM empowers engineers with new capabilities to manufacture complex conformal geometries quicker and at lower costs. It allows, for instance, the embedding of RF front ends into functional structures. In this dissertation, two aspects of AM are explored: (a) The development and characterization of techniques that improve the performance of AM microwave circuits and antennas, and (b) study of complex geometries, such as meshed structures, as an alternative to reduce material usage, cost, and weight of the components.

Micro-dispensing …