Engineering Commons^™

Towards Modeling Of Induction Welding Of Thermoplastic Laminates With A Mixed Finite Element Boundary Element Approach, Florentius Johannes Van Zanten

Theses and Dissertations

There is an increased interest in induction welding of carbon fiber reinforced thermoplastic composite laminates within the aerospace industry. Currently, optimal manufacturing process parameters (e.g., current, power, and frequency settings, coil movement speed, etc.) are determined through an experimental trial-and-error approach. To reduce the need for an experimental approach that can determine the manufacturing process parameters, which would be expensive in both time and money, accurate and computationally efficient numerical tools are desired. This research is focused on improving the existing numerical tool, WelDone, in regard to its speed and accuracy.

WelDone utilizes a hybrid element formulation that combines traditional …

Uncrewed Aircraft Systems For Autonomous Infrastructure Inspection, Michail Kalaitzakis

Theses and Dissertations

Uncrewed Aircraft Systems (UAS) are becoming increasingly popular for infrastructure inspections since they offer increased safety, decreased costs and consistent results, compared to traditional methods. However, there are still many open challenges before fully autonomous, reliable, and repeatable UAS inspections. While a UAS platform has increased mobility and can easily approach hard to reach areas, it has limited range and payload capacity and is susceptible to environmental disturbances. Therefore, current operations are limited to Visual Line of Sight (VLOS) manual inspections that usually result in just a qualitative (visual) assessment of the structure.

The objective of this work is to …

Experimental Investigations Of Yarn Pull-Out Behavior In Kevlar®: Influence Of Applied Metallic Coatings And Effect Of Dynamic Loading, Julie Ann Roark

Theses and Dissertations

Flexible woven Kevlar® textile fabrics are widely used in protective armor applications. Yarn pull-out, comprised of yarn uncrimping (i.e., straightening) and yarn translation, is a major energy absorption mechanism during ballistic impact onto these fabrics, especially for impact velocities below the ballistic limit. Yarn pull-out is influenced by various parameters including inter-yarn friction, pull-out distance, pull-out velocity, transverse pre-tension, fiber diameter, fabric architecture, fabric waviness, fabric count and yarn modulus.

The first part of this thesis investigates yarn pull-out behavior of commercially available Kevlar® KM2+ individual yarns coated with metallic layers (copper, aluminum, aluminum nitride, silver) via a directed vapor …

High-Throughput Computation Of Interfacial Thermal Management Of Wide-Bandgap Semiconductors, Hao-Wen Chen

Theses and Dissertations

As semiconductor electronics, in particular high electron mobility transistors, get hot in operation, people are trying to incorporate different semiconductor materials to solve the problem of heat dissipation to maintain the device efficiency and performance. In this master thesis, two different packages, LAMMPS and almaBTE, that are focusing on micro-scale and atomic scale respectively, are used to simulate the heat transfer process across interfaces in two different scales. In the LAMMPS simulation, the research is exploring how the location of atoms and the thickness of interfacial layers will influence the interfacial thermal conductance. On the other hand, using the almaBTE …

Fabrication Of Asymmetrical Hollow Fiber-Supported Thin Film Membranes, Stack Assembly, And Accelerated Long-Term Stability Test For Oxygen Production From Air, Myongjin Lee

Theses and Dissertations

Air separation is a widely used process for oxygen production. Several separation technologies have been developed for air separation, including cryogenic distillation, swing adsorption, redox process of metal oxides, and electrochemical process. Among these technologies, electrochemical permeation process stands out as a cost-effective and simple process for pure oxygen production from air. The electrochemical permeation process employs a gas-tight membrane to permeate and separate oxygen from air directly, where the membrane conducts both ions and electrons simultaneously. Different membrane designs have been studied to obtain the improved performance for oxygen permeation, typically planar and tubular designs. Among these membrane configurations, …

A Hybrid Experimental-Computational Study: Prediction Of Flow Fields And Full-Field Pressure Distributions On Three-Tab Asphalt Roofing Shingles Subjected To Hurricane Velocity Winds, Troy A. Myers

Theses and Dissertations

A novel hybrid experimental-computational study is performed to predict the flow fields and pressure distributions on the measured shapes of flexible, three-tab asphalt roofing shingles undergoing increasing uplift when exposed to hurricane velocity winds. StereoDIC analysis is performed to measure the transient full-field deformed shapes of full-size three-tab asphalt shingles when subjected to hurricane velocity winds for two hours. Steady state computational fluid dynamics (CFD) simulations of the shingled roof facsimile-plenum region representative of the experiments are successfully performed. The simulations are performed to predict wind loading of the uplifted shingle shapes by utilizing the measured full-field three-dimensional uplifted shapes …

Hybrid Theory-Machine Learning Methods For The Prediction Of Afp Layup Quality, Christopher M. Sacco

Theses and Dissertations

The advanced manufacturing capabilities provided through the automated fiber placement (AFP) system has allowed for faster layup time and more consistent production across a number of different geometries. This contributes to the modern production of large composite structures and the widespread adaptation of composites in industry in general and aerospace in particular. However, the automation introduced in this process increases the difficulty of quality assurance efforts. Industry available tools for predicting layup quality are either limited in scope, or have extremely high computational overhead. With the advent of automated inspection systems, direct capture of semantic inspection data, and therefore complete …

Nondestructive Material Characterization Using A Fully Noncontact Ultrasonic Lamb Wave System For Thin Metals, Nuclear Cladding, And Composite Materials, Elsa Z. Compton

Theses and Dissertations

Effective non-destructive evaluation (NDE) inspection system and methods are highly desired in a broad range of engineering applications including thin metal structure thickness evaluation. Ultrasonic guided waves in thin-walled structures, namely Lamb waves, have gained popularity as a NDE method. By using the ultrasonic waves in conjunction with high spatial resolution multidimensional wavefield measurements, thickness evaluations for thin metals can be achieved. This thesis explores the configuration and application of a fully noncontact ultrasonic Lamb wave NDE system for thickness characterization and evaluation of very thin metal plates. We have tested the actuation and sensing of Lamb waves for thickness …

On The Influence Of Afp-Induced Defects On Mechanical Behavior Of Composite Laminates Under Fatigue Loading, Pierre Chevalier

Theses and Dissertations

The objective of the work presented in this thesis is to propose and validate a numerical solution to quantify the influence of Automated Fiber Placement (AFP) induced defects on the mechanical behavior of conventional composite laminates in fatigue. The work presented here will be divided in six sections. At first, a description of the Automated Fiber Placement process and its associated defects is proposed. In association, two tools developed for a rapid analysis and a progressive damage analysis respectively are discussed and used as an introduction to the work conducted in this thesis. In the second section, an extensive literature …

Characterization Of Nonequilibrium Plasma Discharge In High Water Vapor Concentration, Malik Mohammad Tahiyat

Theses and Dissertations

In recent years, plasma discharge in liquid medium has been a topic of immense interest. Theoretical efforts have been pursued to obtain insight on physicochemical processes being influenced due to trace water vapor either being present as residual or provided at a known concentration. However, studies on discharge at high vapor content are limited. In this study, discharge characteristics of plasma in high water concentration (> 90%) are investigated experimentally for a pressure range of 1 – 15 Torr to maximize vapor loading without condensation. Voltage-current characteristics were obtained over 0- 14 mA of current for each operating pressure; current …

Advancement Of New Solid-Oxide Iron-Air Battery (Soiab) Operated On High-Temperature Oxide-Ion Chemistry, Qiming Tang

Theses and Dissertations

Climate change caused by anthropogenic greenhouse gas (GHG) emissions such as the burning of fossil fuels for power generation and industrial processing is affecting the global climate. To address this critical issue, a transition from fossil energy to renewable energy, especially wind and solar, is necessary. However, to successfully realize this transition, a cost-effective and large-scale stationary electricity storage system is indispensable. In this work, a new type of solid-oxide iron-air battery (SOIAB) operated on high-temperature oxide-ion chemistry is studied for this purpose due to its unique cycling characteristics suitable for large-scale Long Duration Electricity Storage (LDES) applications.

In the …

Fundamental Study Of Multiphase Solid/Molten Carbonate Membranes For Co2 Capture And Conversion, Xin Li

Theses and Dissertations

Due to the burning of fossil fuels and human activities, many greenhouse gases such as carbon dioxide are released into the atmosphere, which causes global warming and has a significant negative impact on the human living environment. Therefore, it is imperative to develop carbon capture technologies that can prevent carbon dioxide emission and reduce carbon dioxide concentration in the air. Further, if the captured carbon dioxide can be converted back to fossil fuels, the emission of carbon dioxide is delayed, and more time is gained to develop new and advanced carbon free and clean energy technologies. Motivated by this thought, …

Purification Of Uranium Tetrafluoride Using Ammonium Bifluoride, Kyle Robert Foster

Theses and Dissertations

Molten salt reactors are being deployed as one of the Generation IV nuclear reactor concepts starting in 2025. While their applications and safety potential are considered extremely advantageous, there is a lack of operating history to draw on, so thorough understanding of proposed molten salt materials’ thermochemical behavior is crucial to their successful implementation.

The most prominent fissile fuel proposed for molten salts is uranium tetrafluoride (UF4) using ²³³U of the thorium fuel cycle. UF₄ is extremely hygroscopic, meaning it will react with moisture and oxygen in its environment, so as-received powders contain significant levels of impurity. In …

Fabrication And Characterization Of Micro/Nanostructured Ceramic Device For Energy Conversion, Yun Gan

Theses and Dissertations

The deteriorating climate is threatening our living habitat and arousing public awareness. To achieve the carbon neutral goal by the middle of 21st century, developing novel technologies to reduce CO₂ emission or promote its capture become urgent. Among them, oxygen permeation membrane (OPM) and solid oxide cell (SOC) are two promising devices for clean energy conversion.

In chapter 1, the background of OPM and SOC are briefly introduced. Fundamental mechanism and application of phase inversion, the key process involved in fabrication of hollow fiber OPM and microtubular SOC are emphatically described. Mixed ionic and electronic conducting (MIEC) perovskites demonstrate …

Searching Extreme Mechanical Properties Using Active Machine Learning And Density Functional Theory, Joshua Ojih

Theses and Dissertations

Materials with extreme mechanical properties leads to future technological advancements. However, discovery of these materials is non-trivial. The use of machine learning (ML) techniques and density functional theory (DFT) calculation for structure properties prediction has helped to the discovery of novel materials over the past decade. ML techniques are highly efficient, but less accurate and density functional theory (DFT) calculation is highly accurate, but less efficient. We proposed a technique to combine ML methods and DFT calculations in discovering new materials with desired properties. This combination improves the search for materials because it combines the efficiency of ML and the …

Leveraging Digital Transformation To Build The Technology Of Tomorrow Using Yesterday’S Equipment, Evan Barnett

Theses and Dissertations

Today’s industry sectors are filled with machines developed years ago. Healthcare, manufacturing, sustainment operations, and many others have equipment that may be reliable, but lacks certain capabilities that the newest technology delivers. The digital environment is becoming a necessity for users who want greater insights into how to improve their processes. A solution to this problem would be to purchase the newest equipment that contains robust measures to generate, collect, and analyze data. However, this solution may not be financially feasible for some and for others may sacrifice machine downtime and reliability. To combat these issues, this research focuses on …

Multi-Fidelity Surrogate And Reduced-Order Model-Based Microfluidic Concentration Gradient Generator Design, Haizhou Yang

Theses and Dissertations

The microfluidic concentration gradient generator (μCGG) is an important device to generate and maintain concentration gradients (CGs) of biomolecules for understanding and controlling biological processes. However, determining the optimal operating parameters of μCGG is still a significant challenge, especially for complex CGs in cascaded networks. To tackle such a challenge, this study presents multi-fidelity surrogate and reduced-order model-based optimization methodologies for accurate and computationally efficient design of μCGGs.

The surrogate-based optimization (SBO) method is first proposed for the design optimization of μCGGs based on an efficient physics-based component model (PBCM). Various combinations of regression and correlation functions in Kriging and …

Implementation Of Stereo Digital Image Correlation For In-Plane Strain Measurements To Quantify The Anisotropic Behavior, Plastic Flow, And Strain Hardening Of Extruded Aluminum Alloy, Farzana Yasmeen

Theses and Dissertations

The efficient use of metals is important in various industries, including aerospace, automotive, and energy systems. In each case, the type and range of combined loading conditions can be quite different. The approaches to stress analysis of such complex engineering components and assemblies often are limited to elastic conditions. For those cases where components are relatively thin, elastic-plastic conditions are present; there is continuing interest in assessing the accuracy of analytic and computational models for combined loading conditions. In such cases, experiments performed with axial and shear loads (e.g., tension-torsion) provide baseline data regarding the relationship between applied stresses and …

Application Of Digital Transformation In The Water Desalination Industry To Develop Smart Desalination Plants, Ibrahim Yousif

Theses and Dissertations

Fresh water shortage threatens the development and prosperity of many countries including several areas in the United States. Sea and ground water reverse osmosis desalination is rapidly becoming a dominant technology for overcoming water shortage threats by providing cost-effective freshwater production. Digital transformation can be used to help facilitate and advance water treatment technologies by reducing costs and minimizing downtime. Digital transformation is a process that encapsulates digital tools and technologies such as cloud computing, machine learning, artificial intelligence, the internet of things, and virtual/augmented reality. It is a process where objects in the physical world are given virtual replicas …

Mechanical Strength Of Sic Composite Tubing Under Uniaxial And Multiaxial Loading, Colton Corley

Theses and Dissertations

Silicon carbide fiber reinforced silicon carbide matrix composite is one of the candidate materials for accident tolerant nuclear fuel cladding concepts. In a Nuclear power plant, the reactions between the fuel, cladding, and coolant in a potential loss of coolant accident(LOCA) are of utmost importance to ensure safety in the accident tolerance of such plants. It is for this reason that SiC(silicon carbide) composite tubes have been selected as a possible alternative to the older Zirconium based cladding methods currently used in the industry, which were a partial cause of the Fukushima 2011 meltdown. To serve as fuel cladding, a …

Development Of Acoustic Metamaterial Noise Barriers And Simultaneously Harvesting Energy Using Smart Materials, Fariha Mir

Theses and Dissertations

In our surroundings abundant energy, we either feel through component vibration or hear noises from acoustic sources. Harvesting these unused and untapped green energy in the form of ambient vibration, and acoustic sounds is an emerging field of research in recent years. Utilization of the energy within a wide band of the frequency spectrum originated from the vibrational sources alone stands as one of the most promising ways to power small electronic devices, smartphones, local structural health monitoring sensors, home, and workshop appliances. These abundant sources of green energy are available in almost all the engineering industries, workshops, manufacturing facilities, …

Development Of A Rapid Compression And Expansion Machine To Characterize The Ignition Propensity Of Multi-Component Liquid Fuels, Jonathan Joseph Morreale

Theses and Dissertations

Combustion has been the primary source for energy production, whether it be from coal, oil, or natural gas, for a very long time. With increasing population and therefore an increased demand for energy, efficiency is becoming a concern. In order to increase efficiency, engines have been downsized and compression ratios have been increased. In doing so, problems have arisen such as knock and low speed pre-ignition. To better understand these problems, an investigation into how fuels ignite at higher pressures is necessary. Real fuels are comprised of multiple components that exhibit significant variations in their own physical and chemical characteristics. …

Effect Of Crystal Size On The Failure Mechanics Of Polymer Bonded Explosives, Chizoba Onwuka

Theses and Dissertations

Polymer bonded explosives (PBXs), typically constitute 80-95% of energetic crystals and 5-20% of a soft polymer binder, are widely used in extreme loading conditions such as rocket propellants and explosive munitions because of their high performance and low sensitivity. The particle size of crystals has a significant effect on the mechanical properties of most polymer particulate composites.

In the study, the effect of particle size on the deformation behavior of PBX under dynamic loading is investigated. The study involves testing polymer bonded sugar (PBS) samples, a well-known mechanical simulant of PBXs, with four different crystal sizes: coarse, intermediate, fine and …

An Investigation Of The Ignition Propensities Of Fuels Perturbed By Nitrogen Monoxide, Ackmer Robinson Iii

Theses and Dissertations

Quantitative structure property relationship (QSPR) regression models were developed based on the chemical functional group distribution of toluene reference fuels (TRF, mixtures of n-heptane, iso-octane, and toluene) for RON, MON, and DCN. The QSPR regression models were developed using DCN measurements from this study as well as RON/MON data available in literature. The correlations between RON/MON and DCN were analyzed. The ignition propensity of TRFs perturbed by NO addition was also investigated in this study. The interactions between the chemical functional groups and NO were investigated using an ignition quality tester (IQT). It was found that the increase in the …

A Multi Physics Integrated Solution For A High-Pressure Stage Turbine Efficiency And Durability, Sanjay Chopra

Theses and Dissertations

World electricity demand is projected to grow at an annual rate of ~ 2.1% to year 2040₁. EIA projects nearly 50% increase in world energy usage by 2050 led by growth in Asia.[28];[29]. It is predicted that the global electricity demand grows at approximately 1.6 % per year from approximately 2008 and forecasted to approximately 2035, twice the rate of primary energy demand. This raises electricity's usage in total final energy consumption from approximately 19% in 2018 to approximately 24% in 2040. Electricity demand growth is set to be particularly strong in developing economies. .[28];[29];[38] As an enabler, to meet …

Reduced Order Modeling Based On Hybrid Snapshot Simulation, Feng Bai

Theses and Dissertations

Reduced order model (ROM) is an emerging technique for rapid and efficient numerical simulation and computation in science and engineering applications. The ROM consists of two stages: (1) the offline snapshot simulation to produce high-quality snapshot data representative of model trajectories, from which the projection subspace can be extracted and used for ROM construction; and (2) the online simulation to utilize the ROM built in stage 1. The snapshot simulation is traditionally performed with full order model (FOM) and is computationally demanding, which is one of the most critical limiting factors for the development and deployment of ROM in real-world …

Optimizing Heat Pipes With Partially-Hybrid Mesh-Groove Wicking Structures And Its Capillary-Flowing Analysis By Simulation, Guanghan Huang

Theses and Dissertations

Heat pipes are known as efficient two-phase heat transfer devices and widely utilized in thermal management of power plants and electronics. The hybrid mesh-groove wick promises to attain a higher thermal performance of the heat pipe by balancing the permeability and capillarity. However, traditional fully hybrid mesh-groove wick presents considerable condensation thermal resistance due to the condensed quiescent working fluid and thick, saturated wick.

In this study, a novel partially hybrid mesh-groove wick has been proposed to enhance the evaporation of L-shaped copper-ethanol heat pipes. L-shaped heat pipe promotes high-efficient draining of condensed liquid by gravity, while traditional straight-shaped heat …

Effects Of Overmolding Process Parameters On Bondzone Quality, Vivek Varma Penumetsa

Theses and Dissertations

Urban air mobility (UAM) vehicles refer to small sized systems that transport people or cargo by air. In recent years, the interest in UAM vehicles has risen to combat traffic congestion, provide faster delivery times, or provide easier access to remote places. To meet potential future demand, traditional aircraft manufacturers must introduce manufacturing technologies that can cope with high production rates. One manufacturing technology aircraft manufacturers are investigating is overmolding, a manufacturing technology common to the automotive industry. Overmolding combines the manufacturing and assembly cycles into one by injection molding a component on top of a substrate. The quality of …

Simulation-Based And Data-Driven Approaches To Industrial Digital Twinning Towards Autonomous Smart Manufacturing Systems, Kaishu Xia

Theses and Dissertations

A manufacturing paradigm shift from conventional control pyramids to decentralized, service-oriented, and cyber-physical systems (CPSs) is taking place in today’s Industry 4.0 revolution. Generally accepted roles and implementation recipes of cyber systems are expected to be standardized in the future of manufacturing industry. Developing affordable and customizable cyber-physical production system (CPPS) and digital twin implementations infuses new vitality for current Industry 4.0 and Smart Manufacturing initiatives. Specially, Smart Manufacturing systems are currently looking for methods to connect factories to control processes in a more dynamic and open environment by filling the gaps between virtual and physical systems.

The work presented …

An Acoustic Emission And Artificial Intelligence Approach To Structural Health Monitoring For Aerospace Application, Joseph Chandler Garrett

Theses and Dissertations

In the area of aerospace and other applications, structural health monitoring (SHM) has been a significant and growing area of research in recent years. Throughout the operational life of aerospace structures, various damage scenarios may manifest, and it is of great concern to the aerospace community to develop methodologies for detecting and assessing these damage scenarios. In this paper, fundamental research on the use of the acoustic emission (AE) approach to SHM for fatigue crack growth is presented. In general, the AE approach to SHM and non-destructive evaluation (NDE) involves the sensing of ultrasonic Lamb waves propagating through a structure. …