Digital Commons Network^™

Additively Manufactured Nature Inspired Morphology For Redesign: Advancing Next Generation Energy Systems, Vanshika Singh

Doctoral Dissertations

To meet cleaner energy goals and increasing demand, energy systems such as gas turbines and power plants are required to be operated under harsh loading conditions like higher temperatures and pressures, fluctuating loads, and corrosive environments. Advanced manufacturing techniques such as additive manufacturing (AM) have put us on the trajectory for next-generation system designs, allowing complex geometries and high-temperature alloys with tailored material properties. We need new and systematic design philosophies to use AM's unique characteristics prudently. For a given functionality, nature tends to provide similar solutions in animate and inanimate structures. We propose to take inspiration from nature's repetitive …

Additive Manufacturing Of Magnetic Materials For Electric Motor And Generator Applications, Haobo Wang

Doctoral Dissertations

This work details the research into the 3D Printing, also known as Additive Manufacturing (AM), of both impermanent and permanent magnets. This work also details the research in enabling such AM magnets in electrical machine applications, primarily motors and generators. The AM processes of many types of magnets are described in detail. The material properties of such AM magnets are also described. The two main types of AM magnets that are discussed in detail are AM NdFeB, and AM Silicon Steel. The implementation of AM NdFeB as rotor magnets, and the implementation of AM Silicon Steel as rotor and stator …

Spall Characteristics Of Additively Manufactured Stainless Steel, Kevin Lamb

Doctoral Dissertations

Additive manufacturing (AM) has rapidly transformed from a novelty prototyping technology into a growing sector of production across a wide range of industries. Much work has been documented in literature to demonstrate the behavior of AM products under static and quasi-static loading conditions. However, the behavior of AM materials under high strain rate loading is not as well understood. This research attempts to advance the fundamental knowledge of the relationship between the unique aspects of AM and the mechanical performance under high velocity impact loading conditions.

This project examines the behavior of AM 316L stainless steel (SS) exposed to high …

In Situ Process Monitoring And Machine Learning Based Modeling Of Defects And Anomalies In Wire-Arc Additive Manufacturing, Eduardo Miramontes

Masters Theses

Wire Arc Additive Manufacturing (WAAM) has made great strides in recent years however, there remain numerous persistent challenges still hindering more widespread adoption. Defects in the parts produced degrade their mechanical performance. Inconsistency in the geometry of the weld beads or undesirable anomalies such as waviness, or humps can lead to loss of geometric accuracy and in extreme cases, when anomalies propagate to subsequent layers, build failure. Such defects can be mitigated by a controls framework, which would require a model that maps undesirable outcomes to information about the process that can be obtained in real time. This thesis explores …

A Study Of The Effect Of Machine Parameters On Defects Produced In Eos Additive Manufacturing Builds, Tina White Malone

Doctoral Dissertations

⁵Additive Manufacturing (AM) is defined in the American Society for Testing and Materials (ASTM) standard F2792 as “a process of joining materials to make objects from 3D model data, usually layer upon layer, as opposed to subtractive manufacturing methodologies. It provides an advanced method for building complex geometries and parts for high performance with a significant cost savings. ⁵⁵It’s advantages include the reduced need for tools and molds commonly used in manufacturing, a large reduction in wasted material, much shorter manufacturing cycles for the building of hardware, and its uniquely inherent ability to produce much more complex shapes. …

Al-Ce-Mn Solidification Phase Selection And Solid-State Phase Transformations, Kevin Dean Sisco

Doctoral Dissertations

The design of Al alloys has become an important topic in Additive Manufacturing (AM). The adoption of Al alloys to AM has been difficult because traditional alloys are prone to processing related defects such as solidification cracking. The Al-10Si-Mg alloy was initially adopted because of its resistance to solidification cracking. However, the Al-10Si-Mg alloy has reduced tensile properties especially at high temperatures, where the silicon phase coarsens readily. Therefore, efforts have been made to design new Al alloys that can take advantage of the AM processing. The goal of new alloys is to optimize based on rapid solidification conditions, while …

Modelling, Sensing, And Control Of Weld Beads In Gravity Aligned And Non-Gravity Aligned Orientations For Wire Arc Additive Manufacturing, Joshua J. Penney

Doctoral Dissertations

Wire Arc Additive Manufacturing (WAAM) has recently developed into a viable manufacturing process for large, complex metal parts. The WAAM process uses a Gas Metal Arc Welding (GMAW) torch mounted to an automated motion platform to execute a predetermined path plan based on a desired CAD geometry. As the desired geometry becomes more complex, it is advantageous to utilize out-of-position welding techniques used by human welders to stabilize the weld pool during the deposition of large overhangs. To ensure part accuracy and quality, adding layers of real-time control to manage various aspects of the WAAM process is critical. First, a …

Design Of Binders For Binder Jet Additive Manufacturing, Dustin B. Gilmer

Doctoral Dissertations

Binder jet additive manufacturing (BJAM) is a versatile AM technique that presents an avenue for advanced manufacturing of powdered materials, including metals, ceramics, and polymers, with high-deposition rates, scalability, and geometric flexibility. BJAM uses ink-jet technology to deposit a binding fluid (binder) into layers of powdered metal, ceramic, or polymeric materials. However, the industrial application of BJAM is currently limited in various applications due to adverse effects from the binder. Despite the fundamental importance of the binders for successful BJAM, the understanding and engineering of the binder is often overlooked. The binder is a determining factor for initial preform formation, …

Assessing Mechanical Performance Of Dissimilar Steel Systems Made Via Wire-Arc Additive Manufacturing, Obed Daniel Acevedo

Masters Theses

Hot stamping is part of a specific type of metalworking procedure widely used in the automotive industry. This research seeks to help make hot stamp tooling component production more cost-effective by using large-scale additive manufacturing. Additive manufacturing can produce dissimilar steel components that can be more cost-effective and time-efficient and allow for complex geometries to be made. A dissimilar steel system consisting of 410 martensitic stainless steel and AWS ER70S-6 mild steel is proposed to make hot stamps, making them more cost-efficient. However, the material interface's mechanical behavior in 410SS-mild steel additively manufactured material systems is not well understood. This …

Quality And Productivity Improvements In Additive Manufacturing, Huseyin Kose

Doctoral Dissertations

Additive manufacturing (AM) is a relatively new manufacturing technology compared to the traditional manufacturing methods. Even though AM processes have many advantages, they also have a series of challenges that need to be addressed to adapt this technology for a wide range of applications and mass production.

AM faces a number of challenges, including the absence of methods/models for determining whether AM is the best manufacturing process for a given part. The first study of this thesis proposes a framework for choosing specific AM processes by considering the complexity level of a part. It has been proven that the method …

Transients In Plastic Instabilities During Thermo-Mechanical Reversals In An Additively Manufactured Ti6al4v, Sabina C. Kumar

Doctoral Dissertations

A complex interaction of process variables in an evolving geometry during Additive Manufacturing (AM), can bring about spatial and temporal transients of temperature and stress within each layer in a part. Although AM shares commonalities with conventional processing techniques such as casting, welding, and thermo-mechanical process, published literature has shown that the steady-state conditions are not strictly valid during AM process. Macro-scale fluctuations of thermal gradients (dT/dx: 10³ to 10⁷ K/m) combined with local changes in thermal expansion coefficients, crystallographic strains and localized stress-strain constitutive properties in conjunction with thermal cycles, can bring about a plastic strain gradient …

Design Of A Cable-Driven Manipulator For Large-Scale Additive Manufacturing, Phillip Chesser

Masters Theses

Additive manufacturing of concrete is a growing field of research, yet current motion platforms do not offer viable routes towards large scale deployable systems. This thesis presents the design and analysis of a novel cable-driven robot for use in large scale additive manufacturing. The system developed, termed SkyBAAM, is designed to be easily deployable to a construction site for on-site additive manufacturing of buildings and other large structures. The design philosophy behind this system is presented. Analysis of this system first explores the kinematics, and stiffness as a function of cable tension. Analysis of the workspace and singularities is also …

Application Of Artificial Neural Nets To A Selective Laser Sintering Additive Manufacturing Process For Fault Detection, Benjamin Terry

Masters Theses

The purpose of this paper is to report recent results demonstrating feasibility of active monitoring and fault probability estimation in the Selective Laser Melting (SLM) process in a Renishaw AM250 machine, through analysis of layer-by-layer surface profile data of Fe3Si powder. The data was collected in-situ during the metal additive manufacturing of a Heat Exchanger section, comprised of a series of conformal channels. Specifically, a shallow artificial neural net (ANN) was trained with high-resolution powder bed surface height data from a laser profilometer and then linked to post-print CT scans which provided the truth-data labelling of each site as faulty …

Evaluating The Effects Of Scan Strategy On Am Annealed Fe-3si Steel Through Understanding Of Solidification Conditions And Thermal Stresses, Michael P. Haines

Masters Theses

Soft magnetic steels have seen recent adoption in additive manufacturing (AM) due to the prospect of reducing eddy currents and hysteresis losses through leveraging of complex geometries and microstructural control. An annealing step will be a significant step for these alloys produced in AM to increase grain size and further reduce hysteresis losses. In this study, thin wall Fe-3Si samples were produced using laser powder bed fusion (L-PBF) using two different scan strategies, with a subset of samples annealed at 1200°C for 5 minutes. The effects of the two different scan strategies on microstructure in the as-built and annealed samples …

The Use Of Optical In-Situ Data Of Tensile Samples To Model Porosity For Part Qualification Of Am 316l, Caitlin Hensley

Masters Theses

Additively manufactured parts often contain porosity that forms during the building process. These defects can affect the part quality and make individual part qualification difficult. In this study, pores were purposefully designed within tensile samples in combinations of three diameters (200m, 350m, and 500m) and three volume percentages (1%, 3%, and 5%) for a total of nine combinations. Each combination was built twice in order to compare the ability of hot isostatic pressing (HIP) and solution annealing (SA) to mitigate pore effects and produce a part that achieves acceptable tensile properties. Two control samples with no purposeful porosity included were …

Rationalization Of Crystallographic Texture Evolution In High Gamma Prime Ni-Based Superalloys During Laser Powder Feed Directed Energy Disposition, Kevin Michael Smith

Masters Theses

Single-crystal nickel superalloy components are widely used in high temperature aerospace applications due to their excellent high temperature strength and creep resistance. Mechanical properties of single-crystal nickel superalloys are affected by chemical composition and the method of manufacture. Production of these components is costly and repair offers opportunity to sustain system performance while reducing costs. Additive Manufacturing by Laser Powder Feed Directed Energy Deposition (DED) is a promising method for repair due to selective application of material and the ability to tailor heat input. However, laser processing of these materials presents several challenges due to the high potential for cracking …

Enhancing The Macroscopic Properties Of Parts Printed Via Fused Filament Fabrication By Incorporating Nanoscopic Additives, Dayton Phillip Street

Doctoral Dissertations

Additive Manufacturing (AM), or 3D printing, provides an alternative route to generate end-stage products by coupling advanced manufacturing techniques with computer modeling. However, parts fabricated by AM are known to have inferior mechanical properties compared to parts prepared by traditional methods, such as injection molding. This principal drawback is attributed to the presence of voids and inefficient adhesion between adjacent filaments, or beads, due to limited diffusion of polymer chains across interbead interfaces. Together these shortcomings also lead to anisotropic mechanical properties in printed parts. While optimizing print conditions or applying post-printing procedures decreases the anisotropy, these methods are incapable …

Torch Mounted Wire Nipper, Steven D. Patrick, Matt Montgomery, Ben Rouse, Garrett D. Foust

Chancellor’s Honors Program Projects

No abstract provided.

Automatic Error Detection And Correction In Laser Metal Wire Deposition - An Additive Manufacturing Technology, Adeola Idowu Adediran

Masters Theses

Additive manufacturing (AM) technology involves building three-dimensional objects by adding material layer-upon-layer under computer control. Metal additive manufacturing offers new possibilities, not only in design, but also in the choice of materials. However, the additive process remains at a lower maturity level compared to the conventional subtractive processes such as milling, drilling and machining among others. Scientifically, there is a safety concern relating to the accuracy of the AM process, how printed products will perform over time and the consistency of their quality. Process accuracy and eventual part quality is compromised due to errors introduced by each of the building …

Approach To Qualification For Electron Beam Powder Bed Fusion In Ti-6al-4v, Sean Lucas Yoder

Masters Theses

Recent developments in additive manufacturing (AM) show promise for using AM manufactured components in a production setting. However, a crucial step for mass producing AM components is to certify these parts for use. One common method for certifying parts is to manufacture tensile coupons alongside any parts. These coupons are characterized and the results are related to the parts. This causes many researchers to focus on the process-material interactions while neglecting build setup. Another issue related to certification of AM parts is the lack of knowledge in the software calculations for a given process. Original equipment manufacturers (OEM), such as …

The Effect Of Hydrogen On Gas Porosity In Laser Powder Bed Fusion Of Alsi10mg, Travis A. Mcfalls

Masters Theses

The density of components built using selective laser melting systems are greatly affected by pore formation during rapid solidification. By limiting the hydrogen content of the AlSi10Mg powder and the solidification through build parameters, gas porosity can be reduced. In this study, three types of porosity were characterized in AlSi10Mg samples built by both SLM and Concept Laser systems. Trends relating to energy input and pore type were established for gas, keyhole, and lack of fusion. The physical mechanisms for each type of pore formation were rationalized relative to solidification parameters such as, thermal gradient and solidification front velocity. Areal …

Metal-Polymer Adhesive Bond Characterization In An Additive Manufacturing Environment, Daniel Seth Elkins

Masters Theses

Recently, the aerospace industry has turned the focus of its manufacturing efforts towards additive methods. For many aerospace applications, however, hybrid materials are preferred for their ability to combine optimal properties from various material sets, and these materials are not yet compatible with large-scale additive manufacturing. To fix this lack of compatibility, new additive methods must be developed that can print dissimilar hybrid materials on one print bed at a large scale, which will require a reliable dissimilar material joining method.Among current joining techniques, one of the most promising for this application is adhesive bonding. Typically, adhesive bonding requires optimizing …

Understanding Process-Structure Relationship For Site-Specific Microstructure Control In Electron Beam Powder Bed Additive Manufacturing Process Using Numerical Modeling, Narendran Raghavan

Doctoral Dissertations

Additive Manufacturing (AM), the fabrication of 3-D parts from CAD models, is a disruptive technology that is transforming the manufacturing industry. In any manufacturing process, understanding the process-structure-property-performance (PSPP) linkage is crucial to predict the lifespan of the manufactured component. In the PSPP linkage, the solidification microstructure (liquid-solid phase transformation) is one of the important factors affecting the mechanical property and performance of the additively manufactured components. During rapid solidification, the solidification microstructure is dictated by the thermal gradient (G) at the liquid-solid interface and velocity (R) of the liquid-solid interface. In this work, the transient heat transfer and fluid …

3d Printed Electronics, Mwamba Bowa

Masters Theses

Additive manufacturing is revolutionizing the way we build and produce a plethora of products spanning many industries. 3D printing, a subset of additive manufacturing, has shown strong potential in reduced energy use, sustainability and cost effectiveness. Exploring avenues that this technology can be utilized is key to improve productivity and efficiency in various applications; for example electronic systems and devices manufacturing.Electronic systems and sub-systems are built using a variety of materials and processes, which require a large carbon footprint, significant waste products and high production time. We have seen experiments of printed electronics using inkjet printing technology to provide a …

Monitoring The Metal Additive Manufacturing Process Through Thermographic Data Analysis, Jacob B. Raplee

Masters Theses

Metal Additive Manufacturing (AM) is the formation of a solid metal part through the layer-wise melting of metal powder, wire, or thin sheets using various heat sources or other bonding methods. This manufacturing method provides nearly limitless complexity with decreased waste, energy needs, and lead time. However, the process faces challenges in part consistency and validation especially for high precision fields such as aerospace and defense. Research has sought to implement robust process monitoring techniques to increase consistency and the reliability of the AM process and detect vital information about the part such as microstructural development, and porosity formation so …

Sustainability Analysis For New Technologies Of Biofuels And Additive Manufacturing, Nelson A. Granda Marulanda

Doctoral Dissertations

This work is a compendium of different sustainability analysis on new technologies. The first chapter performed a Life Cycle Analysis of a biofuel process where pine woodchips are used to create SynGas. The study was done using a 10 tons gasifier, the mass balance of the reaction and an input/output analysis. All the data obtained was input into a freeware LCA software and the results were compared to the use of regular produced natural gas. The second chapter creates a benchmark of energy intensity and presents a case using binder jetting technology. Different Additive Manufacturing technologies energy intensity was reported, …

Graphene And Carbon Nanotube Pla Composite Feedstock Development For Fused Deposition Modeling, Austin Plymill, Robert Minneci, Duncan Alexander Greeley, Jack Gritton

Chancellor’s Honors Program Projects

No abstract provided.