Engineering Commons^™

Mechanical Properties And Microstructure Of Multi-Materials Fabricated Through A Combination Of Lpbf And Ded Additive Manufacturing Techniques, Christopher J. Bettencourt

All Graduate Theses and Dissertations, Fall 2023 to Present

This research explores the use of different metals combined through 3D-printing to enhance the performance of materials, with a focus on making heat exchangers more cost-effective for renewable energy. The goal is to replace a costly high-temperature alloy with a more affordable low-temperature alloy, using metal additive manufacturing for its benefits such as less material waste, faster production, reduced weight, and the ability to print entire assemblies in one go. The study delves into a unique combination of two 3D-printing techniques, Directed Energy Deposition and Laser Powder-Bed Fusion, to create a multi-material composed of stainless steel 316L and a nickel-based …

Estimated Aerodynamic Forces And Moments And Optimal Orientation Of The V-Bat Airframe During Vertical Landing In Gusty Conditions, Parker C. Carter

All Graduate Theses and Dissertations, Fall 2023 to Present

Ship based Unmanned Air Systems (UAS) are an important tool used by the United States Navy for situational awareness and short-range operations. Naval UAS are used to provide real-time intelligence, surveillance, reconnaissance, and target-acquisition while being low cost, mission flexible, and safe. Unfortunately UAS suffer disadvantages with respect to adverse environmental conditions caused by the air being displaced by the ship. The accumulation of one or more adverse conditions is known as airwake. To counteract the effects of airwake, the objectives of this work are to first evaluate the effect of forces and moments during the vertical landing phase of …

Development, Implementation, And Optimization Of A Modern, Subsonic/Supersonic Panel Method, Cory D. Goates

All Graduate Theses and Dissertations, Fall 2023 to Present

In the early stages of aircraft design, engineers consider many different design concepts, examining the trade-offs between different component arrangements and sizes, thrust and power requirements, etc. Because so many different designs are considered, it is best in the early stages of design to use simulation tools that are fast; accuracy is secondary. A common simulation tool for early design and analysis is the panel method. Panel methods were first developed in the 1950s and 1960s with the advent of modern computers. Despite being reasonably accurate and very fast, their development was abandoned in the late 1980s in favor of …

Quantifying The Effect Of Stable Stratification On Low-Reynolds Number Flow Past A Horizontal Cylinder, Holland Kartchner

All Graduate Theses and Dissertations, Fall 2023 to Present

In this research, we study the behavior of flow around a cylinder in the presence of stable stratification, which refers to variations in density throughout the fluid. This phenomenon is observed in natural and industrial settings. We use computer simulations to analyze how stratification affects the flow patterns created by the cylinder. Specifically, we investigate situations where the stratification is perpendicular to the flow direction, and the wake exhibits two-dimensional characteristics. We use spectral-element method based computational fluids dynamics to simulate the phenomena. During the simulations, we vary two important parameters: the Densimetric Froude Number (Fr) and the …

Cislunar Navigation Techniques And Navigation Performance Optimization, Quinn P. Moon

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Nova-C is a lunar lander developed by the private company Intuitive Machines to deliver commercial payloads to the Moon. The IM-1 mission set for 2023 will launch and land the Nova-C near the Moon's south pole. In this research, various navigation techniques are explored to determine the lander's position and velocity during key segments. This process is studied for key mission events including trajectory correction maneuvers (TCMs), lunar orbit insertion (LOI), and descent orbit insertion (DOI). Each mission segment, referred to as an Orbit Determination Segment (OD), is analyzed with three different navigation techniques: Monte Carlo Analysis, Linear Covariance Analysis, …

Convexity Applications In Single And Multi-Agent Control, Olli Nikodeemus Jansson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The focus of this dissertation is in the application of convexity for control problems; specifically, single-agent problems with linear or nonlinear dynamics and multi-agent problems with linear dynamics. A mixture of convex and non-convex constraints for optimal control problems is also considered. The main contributions of this dissertation include: 1) a convexification of single-agent problems with linear dynamics and annular control constraint, 2) a technique for controlling bounded nonlinear single-agent systems, and 3) a technique for solving multi-agent pursuit-evasion games with linear dynamics and convex control and state constraints. The first result shows that for annularly constrained linear systems, controllability …

The Influence Of Surface Roughness Frequency On Rotating Sphere Aerodynamics, Jack C. Elliott

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Solving the problems of increasing highway fuel efficiency, throwing a better curve ball, and preventing an aircraft from stalling all have a common thread: controlling flow separation. Defined by the fast moving flow around an object detaching from the object, flow separation has implications for a broad number of engineering fields. Research regarding flow separation control has led to the understanding that the easiest method for delaying flow separation for a given shape is to vary how turbulent the flow around the object is. Varying this turbulence around an object may be achieved through various methods including changing the …

Aerodynamic Implications Of A Bio‐Inspired Rotating Empennage Design For Control Of A Fighter Aircraft, Christian R. Bolander

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This dissertation presents an analysis of the aerodynamics for an aircraft using a novel, bio-inspired control system. The control system is a rotating tail, that is inspired by the way in which birds use their tail to control their flight. An aerodynamic model for a baseline aircraft and a bio-inspired variant are created by referencing well-known relationships for the aerodynamics of flight, which are then used to analyze the available flight envelope at which each aircraft can reach two different equilibrium states. An analysis of the total aerodynamic control authority of each aircraft is also included along with a preliminary …

Multi-Fidelity Predictions For Control Allocation On The Nasa Ikhana Research Aircraft To Minimize Drag, Justice T. Schoenfeld

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Optimal control settings (camber scheduling) can be used by aircraft to minimize drag at various operating conditions during flight. In this work, camber schedules for minimum drag on the NASA Ikhana are obtained over a range of lift coefficients. A modern numerical lifting-line algorithm is used to predict the lift and drag of the aircraft as a function of operating condition and wing section shape (airfoil camber). The SLSQP optimization algorithm is used to solve for the camber schedule that minimizes drag for a given operating condition. The process is repeated, varying the number of control sections to evaluate the …

Linearized Rigid-Body Static And Dynamic Stability Of An Aircraft With A Bio-Inspired Rotating Empennage, Austin J. Kohler

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The United States Air Force (USAF) will likely seek to remove the vertical tail of next-generation fighter aircraft. This work seeks to characterize the static and dynamic stability and handling qualities of a vertical-tailless aircraft concept that would satisfy the USAF’s goal. This concept aircraft, one modified with a Bio-Inspired Rotating Empennage (BIRE), does not have a vertical tail, and is instead capable of rotating the horizontal tail about the fuselage axis for maneuvering. The dynamic characteristics of the BIRE-modified aircraft are compared to a baseline unmodified aircraft, similar to the F16, with a traditional vertical tail. Linearized aerodynamic models …

Developing A Methane Detector For Aerospace Applications, Michael A. Kirk

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Greenhouse gasses in the atmosphere are raising the global temperature and causing adverse side effects. Of these greenhouse gasses, methane is one of the most impactful, second only to carbon dioxide. One of the methods for determining the concentration of methane in the atmosphere is taking images of the earth from space. The purpose of this project is to further a new imaging technology for detecting methane leaks called FINIS (Filter Incidence Narrow-band Infrared Spectrometer), thus improving our capability to detect and locate methane leaks and reduce greenhouse gas emissions. FINIS has been developed in various stages since 2018 and …

Effects Of Imu Sensor Location And Number On The Validity Of Vertical Acceleration Time-Series Data In Countermovement Jumping, Dianne Althouse

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Many devices are available for measuring the height of a CMJ. An inertial measurement unit (IMU) measures linear acceleration, orientation, and angular velocity. As an alternative to using IMU estimates of flight time, CMJ height could be estimated by integrating the IMU time-series signal for vertical acceleration to derive CMJ take-off velocity in order to track whole-body center of mass (WBCoM) movement, yet this approach would require valid IMU acceleration data. Thus, the purpose of this study was to quantify the effects of IMU sensor location and number on the validity of vertical acceleration estimation in CMJ. Thirty young adults …

Speed Of Small Droplets On Repellent Surfaces, Addison J. Litton

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A droplet of fluid can slide or roll down an angled surface if the droplet doesn’t stick to the plate (e.g., droplets on glass). The most common surface to allow for such this motion are hydrophobic surfaces. One example is a freshly waxed car where the rain beads up and rolls off. Another example is if a pan is heated to a high enough temperature then when small amounts of water are added the droplet will skitter around on the surface for a moment before boiling away. This high temperature effect where droplets rest on a vapor layer underneath cause …

Multidisciplinary Reference Solutions For Performance-Optimized Aircraft Wings With Tailored Aerodynamic Load Distributions, Jeffrey D. Taylor

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Morphing wings, or wings that can change shape during flight, have the potential to substantially reduce the amount of fuel consumed by an aircraft over the course of its flight. However, the extent to which these wings can reduce fuel consumption depends on the design of the wing, including its aerodynamic efficiency and its structural layout, and how the aircraft flies, including its flight altitude and speed. Correctly predicting how these design and operational characteristics interact is critical to predicting how wing morphing may affect aircraft fuel consumption. Many computer prediction tools exist that include the effects of these interactions, …

Novel Patterning Techniques To Improve Digital Image Correlation In Challenging Environments, Weston Craig

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A camera-based measurement technique called digital image correlation (DIC) is beneficial to measure displacement and strain in challenging environments (such as post-irradiation evaluation and high temperature environments) due to its non-contacting nature and ability to obtain measurements over multiple length scales. This technique requires a surface pattern which influences the measurement resolution and accuracy of the measurements. This thesis explores two novel patterning techniques to allow the use of DIC in more challenging environments:

The first is to determine if a pattern created from printed text can be used as a pattern in DIC. Native patterns are patterns already present …

Thermodynamic Analysis Of A Novel Cycle For Nuclear Smr And Heat Transfer Performance Validation Of The Related Supercritical Working Fluids, Benjamin M. Pepper

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Currently, all operating nuclear power facilities in the U.S. follow the same general design and process: light-water reactors boil water into steam using bundles of nuclear fuel rods as a heat source, pumping that steam through a turbine which powers a generator to produce clean year-round electricity. Water is an effective coolant, but other facilities around the world have demonstrated the ability to use non-water-based coolants in nuclear reactor designs, which consequently have their own trade-offs. Some positive consequences of using different reactor designs include enhanced safety, better economics, and cheaper clean consumer energy. The work described in this paper …

Calibration Procedure For Dic Strain Measurements During Vibration-Based Fatigue Testing, Benjamin D. Hill

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Vibration-based fatigue testing is fast and effective method for determining failure characteristics of a material. Often, a small electrical device called a strain gage is bonded to a rectangular plate specimen to measure the deformation of the plate during a test. However, these strain gages break before the plate does, so an alternative method would improve the results obtained from the test. As an alternative to strain gages, Digital Image Correlation (DIC) is a non-contacting, camera-based technique that measures the deformation of an object by comparing digital images taken before and after the object is deformed. During a vibration-based fatigue …

Ng-Torque/Tension Testing Of Bolts With Epoxy Primer, Gabrielle Van Brunt

Undergraduate Honors Capstone Projects

This capstone project is in conjunction with Northrop Grumman (NG). The goal of the project is for NG to apply an epoxy in the future to aerospace structures that they produce. This epoxy is meant to prevent corrosion of threaded joints in the structures. Although NG has the epoxy and has no issues procuring it, NG does not know the properties of the epoxy; it cannot be used until the epoxy’s nut factor is experimentally determined. The epoxy nut factor will be used for design and drawing purposes on various projects. To determine the nut factor, the Aggiepoxy team created …

Small Spacecraft Thermal Control Louvers, James Anthony Mullen

Undergraduate Honors Capstone Projects

Small satellites missions are becoming increasingly complex and are requiring more power. These demands lead to temperature fluctuations on the satellite due to spacecraft layout, sunlight and shadow in orbit, and high-powered instrumentation. Products which provide necessary thermal stability for components on the satellite are desirable to small satellite manufacturers.

In September of 2015, Dr. Allison Evans of the NASA Goddard Space Flight Center filed a patent for an innovative louver system configured for small satellite applications. The design was sized for satellites with a 1U form factor and utilized bimetallic springs to lift the louver flaps. The design was …

Release Of Large Water Droplets, Jeffrey N. Fonnesbeck

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Water is familiar to all human beings and water droplets are an integral part of our daily lives. From irrigation sprinklers to waterfalls we can observe the formation of water droplets. For most, the droplets are so common and mundane that no thought is given to how the droplets form. Scientists have spent many decades detailing the processes that lead to droplet formation. Current theories and experiments agree quite well for specific cases such as pendant drop formation and jet breakup, but in regards to large volumes of free falling liquid there is very little experimental work to confirm the …

Improved Digital Image Correlation Techniques At High Speed And High Temperature, Lindsey J. Rowley

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In extreme environments, such as hot-fire rocket testing, gathering strain data can be challenging due to temperature constraints. Traditional methods for measuring material deformation such as strain gages, a small device attached to a test specimen, cannot withstand the extreme temperature and tend to burn off. When these situations occur non-contacting methods such as Digital Image Correlation (DIC) are preferable. DIC is an optical method of measuring strains across the material’s entire surface by using a camera to track the deformation of a speckle pattern applied to the surface of a deforming object. When used at temperatures above approximately 500°C, …

Seam Shifted Wake In The Magnus And Non-Magnus Directions, John W. Garrett

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

An experiment was done to look at the effect baseball seams can have on how a pitched baseball moves in flight. Both non-spinning and spinning baseballs were analyzed in this study. Data was taken and analyzed at 60, 90, and 110 MPH to determine the influence of velocity and altitude on the ability of seams to alter the trajectory of a pitched baseball. Additionally, a ball's spin causes movement in a certain direction that is dependent on the spin axis. A second focus of this study was on the effect of baseball seams changing the movement in the same direction …

Quantifying The Dynamics Of An Idealized Oil-Plume In Stratified Environment Using Direct Numerical Simulations, Jasmin Ahmed

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Deep-water oil spills such as the incident in the northern Gulf of Mexico 2010, produce turbulent oil plumes. Multiphase turbulent plumes under stratification are simulated to understand the dynamics of oil plume in oceanic environment. The evolution of the plume is strongly affected by the level of turbulent mixing during the rise of oil through the stratified water. The relative velocity due to the difference in density between oil and water causes slip of oil in water. The plume has been modeled as a two fluid mixture-model, which allows the use of one continuity and momentum equation for the oil-water …

Collective Motion In Pelotons And Fish Schools: Observation And Modeling, Syed Rafid Rahman

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In recent years there has been a sharp increase in deriving inspiration from nature for engineering applications. However there has been lack of high-resolution data from which insights into collective behavior can be drawn and models can be validated. In this imaging based thesis, data from high-speed, overhead cameras, and GPS tracking are used to collect position and sensory data for large groups of 40 or more members. These data helps us understand how different members (fish, cyclists) of a group interact with each other in collective motion. The focus of this work is to find how individual behavior leads …

The Effect Of Bit Depth On High Temperature Digital Image Correlation Measurements, Steven Robert Jarrett

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Digital Image Correlation (DIC) is a camera-based method of measuring mechanical displacement and strain which is commonly used in high-temperature experiments due to its ability to take contactless measurements. High-temperature DIC is challenging due to light emitted from the sample which can saturate the camera sensor. Blue-DIC and UV-DIC have been developed to minimize this effect, but the maximum sample temperature range of DIC remains a function of the camera and camera settings. Bit depth, also referred to as color depth or number of bits, is an important camera setting which affects the dynamic range of an image, but which …

High-Magnification Digital Image Correlation Techniques For Aged Nuclear Fuel Cladding Testing, Robert Scott Hansen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Nuclear fuel cladding in light water reactors, often made of zirconium alloys, is naturally made more brittle by exposure to the water coolant during normal reactor operation. However, this embrittlement by zirconium hydrides changes the mechanical behavior of the cladding material, affecting how it will deform and what may cause it to fail. Because the cladding already has different properties in different material directions, mechanical testing also needs to be direction specific. In addition, to understand the effects that these microscale hydride features have, measurements of deforming cladding need to be at a microscale. This dissertation describes several high-magnification innovations …

Characteristic Of The Dynamics Of Disorder In Crystalline And Amorphous Materials, Amir Behbahanian

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This work provides the evidence to apply simulation methods that are applicable to systems with structural randomness to simulate crystalline materials at high temperatures. My work not only open the avenue to expand the simulation capability of materials but also provides insight to the physics of vibrations of atoms under different temperature and for different types of materials. I have also evaluated the reliability of Molecular Dynamics simulations at the frequency level and found that theses types of simulations, despite the previous belief, are reliable at low temperatures but up to a measurable frequency. In addition, the result of my …

Sensitivity Study For Uav Gps-Denied Navigation In Uncertain Landmark Fields, Samantha D. Burton

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This document provides two 2D simulation sensitivity analyses regarding a drone’s flight characteristic (state) errors within a GPS-denied region. The research focuses on a development and investigation of utilizing a camera to simultaneously determine a drone’s state while locating landmarks, where there is uncertainty in the landmarks’ exact positions prior to the mission (SLAM). This SLAM method is performed in regions with limited access to GPS. Furthermore, there is development and investigation of controlling the drone in conjunction with SLAM using potential error-reducing control parameters. Objectives are to quantitatively understand the UAV’s sensitivity of position errors to sensor grade and …

Impacts In Fluids: Forces, Scaling Laws And Bouncing Modes In Projectile Impacts On Water Pools And Droplets, Rafsan Rabbi

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Projectile impacts in quiescent water pool are synonymous with intriguing splash phenomena and rich underwater physics. Depending on the material property, geometry and surface conditions of the impacting projectiles coupled with the geometric properties of the water pool (e.g., depth, width etc.), contrasting events like sub-surface cavity formation or bouncing of macro-droplets unfolds over millimetric timescales.

In this dissertation, I present four different studies that look at different aspects of impact events with the help of high-speed imaging techniques and implementation of other sensory data acquisition instruments. Firstly, I look at the force of impact associated with projectile water entry …

Surrogate Optimization Model For An Integrated Regenerative Methanol Transcritical Cycle, Yili Zhang

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In order to reduce the cost ($) per megawatts hour (MWh) of electrical energy generated by a nuclear power cycle with a novel small modular reactor (SMR), a new SMR-based nuclear power cycle with Methanol as working fluid was designed. It was built virtually with the Python & Coolprop software based on all components’ physical properties, and it is therefore called the physics-based model. The physics-based model would require seven user-defined values as input for the seven free design parameters, respectively. The physics-based model outcomes include LCOE (the cost per megawatts hour of electrical energy generated by the …