Mechanical Engineering Commons^™

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 …

Image Based Processing For Weld Defect Detection, Shems-Eddine Belhout

Masters Theses

There is a growing need for automation in the welding industry due to a growing shortage in skilled welders. TIG [Tungsten Inert Gas] welding, a method of welding that uses an electrode shielded by gas and is fed externally by a wire, is incredibly advantageous for its precise heat control. TIG welding is considered the standard for nuclear application which requires highly precise welds to be performed. Robotic welding can address this issue, and one major problem that occurs during welding is welding defects. Typical weld defect detection requires a highly knowledgeable welder or destructive and nondestructive evaluation. Destructive evaluation …

Trajectory Planning Of Non-Gravity Aligned (Nga) Segments In Arbitrary Directions For Large Scale Additive Manufacturing Of Metals (Lsamm), James Logan Mcneil

Doctoral Dissertations

Traditionally, slicing and path planning are done along the gravity-aligned direction of a part, causing more complex geometrical shapes to have unsupported overhangs. Wire Arc Additive Manufacturing (WAAM) has typically handled overhangs with a robotic part positioner; but, to extend the current capabilities of LSAMM, a new framework for slicing and building parts out of gravity alignment has been developed. The proposed framework focuses on segmenting more complex geometrical parts into gravity-aligned (GA), non-gravity aligned (NGA), and transition zones to support tool-path generation. GA and NGA segments can be planned with traditional slicing techniques, but the NGA tool-paths must be …

Eastman Guide Rail Project, Camryn J. Hurley, Jace Lyon, Isaiah Wallace, Cole Thomas, Erin Bennett

Chancellor’s Honors Program Projects

No abstract provided.

A Numerical Optimization Study Of A Novel Electrospray Emitter Design, Joshua H. Howell

Masters Theses

The low thrust and high specific impulse of electric propulsion has been brought to the forefront for CubeSat and small spacecraft applications. Electrospray thrusters, which operate via electrostatic principles, have seen much research, development, and application in recent years. The small sizes of the spacecraft that utilize electrospray thrusters has focused development into the miniaturization of this technology to the micro-scale. Miniaturization introduces design challenges that must be addressed, including power supply mass and footprint requirements. This consequence requires investigation into the effects of design choices on the thruster onset voltage, defined as the voltage at which ion emission begins. …

Experimental And Computational Study Of Determining Mass Transport Parameters In Vanadium Redox Flow Batteries, Tugrul Y. Ertugrul

Doctoral Dissertations

Vanadium redox flow batteries are a promising large-scale energy storage technology, but a number of challenges must be overcome for commercial implementation. At the cell level, mass transport contributes significantly to performance losses, limiting VRFB performance. Therefore, understanding mass transport mechanisms in the electrode is a critical step to mitigating such losses and optimizing VRFBs.

In this study, mass transport mechanisms (e.g. convection, diffusion) are investigated in a VRFB test bed using a strip cell architecture, having 1 cm² active area. It is found that diffusion-dominated cells have large current gradients; convection-dominated cells have relatively uniform current distribution from …

Design And Simulation Of A Supervisory Control System For Hybrid Manufacturing, Michael Buckley

Masters Theses

The research teams of Dr. Bill Hamel, Dr. Bradley Jared and Dr. Tony Schmitz were tasked by the Office of Naval Research to create a hybrid manufacturing process for a reduced scale model of a naval ship propeller. The base structure of the propeller is created using Wire Arc Additive Manufacturing (WAAM), which is then scanned to compare created geometry to desired geometry. The propeller is then machined down to match the desired geometry. This process is iterated upon until the final product meets design tolerances. Due to the complex nature and numerous industrial machines used in the process, it …

Effects Of Pillar And Sealing Design On Thermal And Mechanical Performance Of Vacuum Insulated Glazing, Wenyuan Zhu

Masters Theses

Vacuum insulated glazing with a low-emittance coating has a great market potential as an effective transparent insulator. The thermal insulating performance of VIG is determined by its design, including material selection and configuration of different components. Thermal conductance of the vacuum gap, as a transport bottleneck, is one of the primary factors controlling the thermal transport across VIG. In particular, since support pillars and sealings provide the main thermal transport channels across the vacuum gap, increasing the pillar and sealing thermal resistance is a key strategy for effective thermal insulation, while maintaining the vacuum space and mechanical strength of VIG. …

Vibration Behavior In Modulated Tool Path (Mtp) Turning, Ryan William Copenhaver

Doctoral Dissertations

This project studies the process dynamics and surface finish effects of modulated tool path (MTP) turning. In MTP turning, a small amplitude (typically less than 0.5 mm), low frequency oscillation (typically less than 10 Hz) is superimposed on the feed motion by the machine controller to intentionally segment the traditionally long, continuous chips. The basic science to be examined is the vibration behavior of this special case of interrupted cutting, which is not turning because the chip formation is intentionally discontinuous and is not milling because the time-dependent chip geometry is defined by the oscillatory feed motion, not the trochoidal …

Investigating Localized Performance And Mass Transport Phenomena In Polymer Electrolyte Water Electrolyzers, Frida Helena Roenning

Masters Theses

In the face of increasing demand for renewable energy sources to replace fossil fuels, current technologies face the issue of steady energy supply from source to power distribution. As most current renewable energy methods either rely on intermittent natural sources or are geographically bound, they require an energy storage medium. Polymer Electrolyte Water Electrolyzers are a theoretically ideal solution to this demand, but they require some performance improvements in practice to be economically viable. This study analyses the current distribution in such electrolyzers in the aim of gaining insight to improve their performance. The current distribution diagnostic can capture local …

Characterization Of A Digital Holography Diagnostic For In Situ Erosion Measurement Of Plasma-Facing Components In Fusion Devices, Cary Dean Smith

Doctoral Dissertations

Fusion energy devices, particularly tokamaks, face the challenge of interior surface damage occurring over time from the heat flux of the high-energy plasma they generate. The ability to monitor the rate of surface modification is therefore imperative, but to date no proven technique exists for real-time erosion measurement of planar regions of interest on plasma-facing components in fusion devices. In order to fill this diagnostic gap, a digital holography system has been established at ORNL [Oak Ridge National Laboratory] for the purpose of measuring the erosion effects of plasma-material interaction in situ.

The diagnostic has been designed with the …

Final Design Report For The Bioburden Pre-Cleaning Device And Dr. Mark Rasnake At The University Of Tennessee Medical Center, Katherine Elizabeth Stiles, Megan Pitz, Kayla Franklin, Simran Dayal, Austin Bullock

Chancellor’s Honors Program Projects

No abstract provided.

Muse 1: Interactive Water Table, Sarah R. Higginbotham

Chancellor’s Honors Program Projects

No abstract provided.

Sound-Proof, Fire Resistant, Leak-Free And Super-Insulated Hvac Ducts, James Fitzsimmons Ii, Ahmed Alyousef, Kyle Dirksen, Nathan Ware, William Miller

Chancellor’s Honors Program Projects

No abstract provided.

Dynamic Monitoring And Life Prediction Of Internal Strain-Gage Balances, David Leon Yoder

Masters Theses

Wind tunnel test customers continue to push the limits by producing air vehicle designs that produce high aerodynamic loads at the desired test conditions. These loads are a combination of steady aerodynamic, unsteady aerodynamic, and inertial forces. A methodology to monitor the health of a wind tunnel strain-gage balance has been developed. The objective of this methodology is to define the stress limits of the balance and monitor these limits so the balance can be safely tested without failure of the balance. A balance failure could result in costly damage to the wind tunnel model, support system, and the wind …

Tracking Of Human Joints Using Twist And Exponential Map, Xiaodong Yang

Masters Theses

Motion tracking system in the home-based environment exhibits attractive advantages for stroke patients. Current methods suffer from incapability of accurately tracking movements with high degree of freedoms. Besides hardly meeting the predefined position during inertial sensor mounting also affects system's performance.

To tackle these challenges, a motion tracking system using twist and exponential map technology is developed in this paper. Firstly, a kinematic model for trunk and upper extremity is designed. Based on this model, twist and exponential map method which updates frames in their initial coordinates instead of transforming coordinates from one frame to another presents high efficiency and …

Jet Flow Validation Of Positron Emission Particle Tracking Utilizing High Speed Video, Seth Thomas Langford

Masters Theses

Positron Emission Particle Tracking (PEPT) generates 4D Lagrangian particle trajectories and is used to evaluate flow in granular media and complex geometries where optical interrogation methods are not possible. A Multi-Particle PEPT (Multi-PEPT) approach was developed by the University of Tennessee Thermal Fluids Group capable of finding and tracking many particles simultaneously to extend the utility of the PEPT method. This thesis compares 4,014 trajectories generated using the Multi-PEPT method with 3,055 trajectories generated from High Speed Video (HSV) data. All trajectories are acquired in an acrylic test section with water flow using resin beads. The flow geometry includes a …

Evaluation Of Fuel Flow Measurement Uncertainty In A Turbine Engine Test Cell, Paul Andrew Wright

Masters Theses

The evaluation of measurement uncertainty is an essential part of measurement and data analysis. Measurement uncertainty is itself a measure of the “goodness” of the measured data and helps the analyst to make decisions based on the data. In the turbine engine testing world, accurate measurement of fuel flow is critical. Specific fuel consumption is a combination of thrust and fuel flow and is used to calculate the allowable payload and range of an aircraft as well as the cruising speed. Naturally, test customers (engine manufacturers, aircraft designers, and operators) are very sensitive to the accuracy of fuel flow measurement. …

Zero Energy Ready Multifamily Dwellings For The Redevelopment Of Downtown Knoxville, Tn, William Twickler, Ben Webb, Georgia White

Chancellor’s Honors Program Projects

No abstract provided.

Toward Direct Biosynthesis Of Drop-In Ready Biofuels In Plants: Rapid Screening And Functional Genomic Characterization Of Plant-Derived Advanced Biofuels And Implications For Coproduction In Lignocellulosic Feedstocks, Blake Lee Joyce

Doctoral Dissertations

Advanced biofuels that are “drop-in” ready, completely fungible with petroleum fuels, and require minimal infrastructure to process a finished fuel could provide transportation fuels in rural or developing areas. Five oils extracted from Pittosporum resiniferum, Copaifera reticulata, and surrogate oils for Cymbopogon flexuosus, C. martinii, and Dictamnus albus in B20 blends were sent for ASTM International biodiesel testing and run in homogenous charge combustion ignition engines to determine combustion properties and emissions. All oils tested lowered cloud point. Oils derived from Copaifera reticulata also lowered indicated specific fuel consumption and had emissions similar to the ultra-low sulfur diesel control. Characterization …

Neutron Imaging Of Lithium Inside A High-Temperature Heat Pipe, Eric Henry Kirchoff

Masters Theses

Neutron imaging of a high-temperature Mo-Li [molybdenum-lithium] heat pipe has been performed to assess Li flow visualization. The high neutron attenuation cross section of Li allows for imaging inside the heat pipe shell structure, which has a lower value of neutron attenuation, making neutron radiography an ideal choice for characterizing Li movement.

The gravity assisted, cylindrical heat pipe was heated to 903^oC [degree] using a wire resistance Mo heater operating under vacuum. This Mo-Li heat pipe is 35 cm long with a square internal geometry 2.2 cm per side, utilizing small corner radii as the wicking structure for …

Water Transport In Polymer Electrolyte Fuel Cells: An Exploration Of Net Water Drag In Real Time, Susan Katherine Reid

Masters Theses

Polymer electrolyte fuel cells (PEFCs) are a promising alternative energy source. One challenge preventing widespread use of this technology is water management. A balance must be reached between providing sufficient water for membrane ionic conductivity while maintaining low enough water content to mitigate the reduction of available reaction sites in the cathode catalyst layer due to liquid water build up. Much exploration of this area of fuel cell research has been conducted, but the details of water transport in an operating fuel cell are not yet fully understood. The motivation of this work was to elucidate mass transport phenomena occurring …

Heat Transfer Analysis Via Rate Based Sensors, Jake Erik Plewa

Masters Theses

This work presents an integrated rate-based sensor and method for resolving the surface heat flux of a fundamental inverse heat conduction problem without numerical regularization or differentiation in a semi-infinite geometry that additionally accounts for thermocouple delay due to its intrinsic time constant. The sensor uses well-designed analog filters to directly regularize raw voltage data to eliminate the need for numerical regularization methods. The sensor can also be used in a series of well-designed voltage-rate interfaces that directly measure the voltages from in-depth thermocouples, which are used in conjunction with the thermocouple calibration curve to provide higher-time derivatives of the …

Droplet Characterization In The Wake Of Steam Turbine Cascades, Adam Charles Plondke

Masters Theses

In low-pressure steam turbines, water droplet formation on the surfaces of stationary stator blades can lead to erosion on downstream turbine blades and other equipment. One property that affects the size of the droplets that are formed is the adhesive forces between the water and the surface of the stator blade. The adhesive forces hold the droplets to the surface where they may combine, forming increasingly larger droplets. Eventually, the aerodynamic forces will tear the droplets off the surface, carrying them downstream.

To study the effect of stator surface properties on the droplet size distribution, four cascades of stator blades …

Test Size And Volume Effects On Fatigue Behavior Of Bulk Metallic Glasses (Bmgs), Qingming Feng

Masters Theses

As a potential structural material, performance of bulk metallic glasses (BMGs) under cyclic loading is critical in applications. Among the mechanical properties of metallic glasses, the fatigue behavior received less attention and is not well understood. BMGs exhibit significant size effects on the mechanical behavior under monotonic loading, such as compression, tension, and bending. At the same time, different test-volume could lead to a distinct difference in the mechanical behavior of BMGs.

The fatigue behavior of the Zr_52.5Cu_17.9Ni_14.6Al_10.0Ti_5.0 [atomic percent (at. %)] BMG alloy (Vitreloy 105) with different sizes has been …

A Method For Performance Analysis Of A Ramjet Engine In A Free-Jet Test Facility And Analysis Of Performance Uncertainty Contributors, Kevin Raymond Holst

Masters Theses

Ramjet and scramjet engines are being developed to provide a more fuel efficient means of propulsion at high Mach numbers. Part of the development of these engines involves test and evaluation of an engine in ground facilities as well as in flight. Ground facilities, like Arnold Engineering Development Center (AEDC) and those at engine manufacturers like General Electric (GE) and Pratt & Whitney (PW), have decades of experience testing traditional turbine engines and much less experience testing full scale ramjet engines.

Testing a supersonic engine model in a free-jet mode presents a host of challenges not experienced during traditional direct …

Residential Attic Ventilation In A Hot And Humid Climate: Effects Of Increased Ventilation On Thermal Performance And Moisture Control, Stanley Arthur Atherton

Masters Theses

The reality of the effect of natural ventilation in a residential attic cavity has been the topic of many debates and scholarly reports since the 1930’s. The purpose of ventilating an attic cavity is to prevent collection of condensate on the structural surfaces, and to create a thermal buffer between the conditioned space and the ambient air. The current standards are not specific to climate zone, despite the fact that each climate zone may require ventilation for very different reasons.

To address the issue of ventilation effects in a hot and humid climate, a Natural Exposure Testing facility was constructed …

Thermocouple Temperature Measurements For Twin Jet Thermal Mixing, Spero Michael Peters

Masters Theses

Thermocouples are commonly used devices for temperature measurement. This study concerns the implementation of thermocouples to collect thermal mixing data in an environment in which two parallel water jets are mixing. The measurements are taken with the purpose of modeling the jet mixing region so that Computational Fluid Dynamics (CFD) models can be validated against the test data. This thesis covers the design, construction, implementation and evaluation of a thermocouple system for immersion in a water environment to measure the thermal mixing of twin jets.

The measurement system being used is a thermocouple rake whose design and fabrication is covered. …

Effects Of Supercooled Water Ingestion On Engine Performance, Rick Hutchings

Masters Theses

An aircraft will encounter freezing rain, snow, and ice during ground operation and flight. In cold conditions, ice may form on th einlet and internal stators and rotors of the gas turbine engine. When ice accumulates on blades (and/or stators), the aerodynamic characteristics of the blades change due to the altered size, shape, and roughness. This change causes the blade to no longer operate at its design point and decreases compressor performance. Therefore, characterization of the aerodynamic performance is required to define the associated losses due to the effects of supercooled liquid water ingestion. This characterization can be accomplished through …

Solar Decathlon Controls, James Mitchel Routh, Travis Lathrop, Colby Jarrett, Zach Cross

Chancellor’s Honors Program Projects

No abstract provided.