Characterization Of Additively Manufactured Ti-6al-4v Yield Behavior And The Influence Of Varied Build Layer Heights,
2024
Air Force Institute of Technology
Characterization Of Additively Manufactured Ti-6al-4v Yield Behavior And The Influence Of Varied Build Layer Heights, Joseph Puglisi
Theses and Dissertations
This study evaluates the yield behavior of additively manufactured Ti-6-4 specimens in combined loading. Specimens were probed for yield across multiple load combinations along a given yield surface, holding pin one mode while applying load increments in the other mode until yield was detected. In combined loading, the yield surfaces across varied print parameters showed statistically significant, but negligible differences. This research sought to characterize the yield behavior across print parameters with the goal of increasing manufacturability. Ultimately, the benefits of the smaller print powder did not outweigh the increased manufacturing time. Furthermore, the comparison of material behavior in subsequent …
Evaluating Butterfly Orbits In The Earth-Moon Corridor For Ssa, Lunar Surface Surveillance, And Cislunar Disposal,
2024
Air Force Institute of Technology
Evaluating Butterfly Orbits In The Earth-Moon Corridor For Ssa, Lunar Surface Surveillance, And Cislunar Disposal, Contessa G. Norris
Theses and Dissertations
The increased space activity in the region of cislunar space has created a high demand to identify, track, and monitor Resident Space Objects (RSOs) and provide cislunar disposal routes for RSOs. This research investigates the practicality of various satellite maneuvers between orbits chosen from the butterfly and dragonfly orbit families. Several simulated trajectories are compared to show the feasibility of performing a maneuver in cislunar and lunar space between the L1 and L2 Lagrange points. Additionally, lunar surface space situational awareness (SSA) capabilities of northern and southern butterfly (BN/BS) orbits were evaluated and compared to provide the most favorable dynamic …
Computational Modeling Of Single Shear Bolted Joints In Hybrid Composite Laminates With And Without Film Adhesive,
2024
Air Force Institute of Technology
Computational Modeling Of Single Shear Bolted Joints In Hybrid Composite Laminates With And Without Film Adhesive, Cameron S. Mcmahan
Theses and Dissertations
This research explores the effectiveness of predicting composite failure subject to quasi-static loading conditions using computational methods. FEA models were created using Abaqus and were employed to predict composite yield and initial failure behavior. Boundary conditions are generated to replicate the loading scenario seen in the experimental tests. Computationally predicted structural response of the composite range in accuracy from a 2% difference compared to experimental values to a maximum of 63%.
Trajectory Optimization Via Direct Collocation Methods Of Boost-Glide Vehicle With Newtonian Aerodynamic Model,
2024
Air Force Institute of Technology
Trajectory Optimization Via Direct Collocation Methods Of Boost-Glide Vehicle With Newtonian Aerodynamic Model, Andrew Bonavita
Theses and Dissertations
In this work, a Newtonian aerodynamic model was developed for an elliptic cone glide geometry at a variety of angles of attack, and a functional relationship between an input angle of attack and the vehicle lift and drag coefficients was developed. This model was used in a direct orthogonal collocation framework to simulate a series of boost-glide trajectories, with objectives of minimum distance to target, minimum time to target, and maximum velocity to target. The optimal control problem was then expanded into a reachability study, considering a wide range of additional scenarios, along with studies on the vehicle range capabilities. …
Rapid Passive Safety Determination Using Backward Reachability For Spacecraft Rendezvous And Proximity Operations,
2024
Air Force Institute of Technology
Rapid Passive Safety Determination Using Backward Reachability For Spacecraft Rendezvous And Proximity Operations, Kealy A. Murphy
Theses and Dissertations
As the prevalence of autonomous space systems rise, there is an urgent demand for robust and precise safety analysis. The future of RPO necessitates coordination of satellites in a dynamic and congested space environment while avoiding collisions. Passive safety in RPO refers to the implementation of strategies that minimize the collision risk in the event of orbital or control deviations. This multifaceted problem includes maintaining KOZ, utilizing predictive modeling to anticipate collision scenarios, and designing spacecraft with robust GNC systems allowing for timely course corrections. The current literature’s focus has been on the separation distance between spacecraft as a primary …
Optimal Trajectory Solutions For Unmanned Pursuer/Evader Offensive Counterair Including Engagement Zone,
2024
Air Force Institute of Technology
Optimal Trajectory Solutions For Unmanned Pursuer/Evader Offensive Counterair Including Engagement Zone, Alexander Hansen
Theses and Dissertations
This work considers a two-actor scenario of a faster, unmanned pursuer with an engagement zone (EZ) and a non-maneuvering mobile evader. The pursuer aims to capture an evader with a circular EZ. The EZ is dynamic and shifts as a function of the evader’s velocity vector. As the evader’s strategy changes, the EZ relative to the pursuer adjusts based on relative heading and speed of the two agents. Using nonlinear optimal control techniques, the optimal trajectory and minimum time to engage the evader are determined for various pursuer initial headings and positions through MATLAB simulation. The results build a control …
Influence Of Environmental Barrier Coatings On The Overall Effectiveness Of A Film Cooled Ceramic Matrix Composite Plate,
2024
Air Force Institute of Technology
Influence Of Environmental Barrier Coatings On The Overall Effectiveness Of A Film Cooled Ceramic Matrix Composite Plate, Shane P. Lindsay
Theses and Dissertations
Silicon carbide ceramic matrix composites, a promising new potential upgrade over the conventional metals currently used for jet engine turbine blades, have a propensity to oxidize in a combustion environment. Engine manufacturers often apply environmental barrier coatings to prevent the composites from oxidizing. What is unclear, however, is how environmental barrier coatings effect underlying composite temperatures. This research examined the coatings’ effects by first characterizing the influence of environmental barrier coatings on the underlying temperature of a protected ceramic, then evaluating the significance of lateral conduction for cooling a coated ceramic, and finally comparing cooling results for coated and uncoated …
Positioning, Navigation, And Timing (Pnt) Study For Select Multibody Environments,
2024
Air Force Institute of Technology
Positioning, Navigation, And Timing (Pnt) Study For Select Multibody Environments, Kaitlin R. Roberts
Theses and Dissertations
In the renewed 21st-century race to the Moon, the demand for heightened mission capabilities in the cislunar region, lunar surface, and beyond is imperative. With an escalating number and complexity of lunar missions, persistent positioning, navigation, and timing (PNT) capabilities are becoming paramount. This thesis presents innovative lunar PNT architectures designed to provide continuous coverage of the lunar South Pole, near-continuous coverage of the entire lunar surface, and coverage of the Earth-Moon Corridor. As space faring countries advance from lunar exploration to Mars, similar assets are essential for astronaut exploration in this extraterrestrial environment. Additionally, this thesis introduces and meticulously …
Preliminary Assessment Of Cislunar Disposal Orbits,
2024
Air Force Institute of Technology
Preliminary Assessment Of Cislunar Disposal Orbits, Ryan M. Sargent
Theses and Dissertations
This thesis investigates the disposal of end-of-life spacecraft from key orbits with a focus on minimizing delta-v expenditure and preventing debris propagation. Simulated Lyapunov and halo orbits around the L2 Lagrange point are analyzed for disposal feasibility. Both impulsive and continuous thrust methods are explored to achieve disposal trajectories. Continuous thrust will be modeled after a Hall thruster utilizing electric propulsion. Leveraging the Circular Restricted Three Body Problem framework, low delta-v cost trajectories are computed, with a multi-level correction algorithm optimizing total delta-v via heteroclinic connections. The study assesses various delta-v amounts for Earth-Moon system escape and evaluates the potential …
Origami Application And Attitude Control Investigation Of Space-Based Mirror System,
2024
Air Force Institute of Technology
Origami Application And Attitude Control Investigation Of Space-Based Mirror System, David J. Garcia
Theses and Dissertations
Imaging and inspecting Resident Space Objects (RSO) have gained increasing importance in Space Situational Awareness (SSA) missions. These missions are driven by the necessity to perform satellite repairs, refueling, de-orbiting, and orbital debris reduction. However, the challenging lighting conditions in space often hinder these tasks. To overcome this challenge, a novel concept has been proposed—deploying mirrors from servicer satellites. These mirrors would harness solar energy to illuminate dimly-lit RSOs, enabling imaging, inspection, repair, and refueling operations. In this context, servicer satellites play a pivotal role in controlling the reflected light beam and precisely positioning themselves to illuminate RSOs effectively. Notably, …
A Nonlinear Least Squarees Approach To Orbit Determination In Near-Earth Orbits,
2024
Air Force Institute of Technology
A Nonlinear Least Squarees Approach To Orbit Determination In Near-Earth Orbits, Ryan M. Vorst
Theses and Dissertations
This work explores relevant scenarios to implement a Frequency on Arrival method using nonlinear least squares to determine a transmitting satellite’s orbit based only on measurements of the received radio frequency. Multiple relevant collection geometries, such as a target in prograde low earth orbit, in retrograde low earth orbit, in sun synchronous orbit, in near-perigee highly elliptical orbit, in near-apogee highly elliptical orbit, and in geosynchronous orbit, are simulated to collect theoretical received frequency data. Once data collection has been simulated, the theoretical apparent frequencies recorded are used in a nonlinear least squares method with differential correction to find a …
3- And 6-Degree-Of-Freedom Investigation Of Aerobraking To Support Cislunar And Planetary Operations,
2024
Air Force Institute of Technology
3- And 6-Degree-Of-Freedom Investigation Of Aerobraking To Support Cislunar And Planetary Operations, Erica C. Higginbotham
Theses and Dissertations
The first aerobraking experiment occurred in 1991 as part of the Hiten spacecraft’s cislunar survey mission, while the first non-Earth aerobraking experiment occurred in 1993 as part of the Magellan spacecraft’s mission to Venus. Although making only two trans-atmospheric passes to reduce its apogee altitude, the success of Hiten’s experiment led to the implementation of aerobraking by Magellan, reducing its orbit from elliptical to nearly circular over a span of 70 Earth days by leveraging aerodynamic drag to reduce its orbital energy via transiting the upper region of Venus’ atmosphere. The Magellan experiment helped prove the viability of aerobraking for …
Exploratory Analysis Of Cislunar Disposal Options For Select L1 And L2 Orbit Families,
2024
Air Force Institute of Technology
Exploratory Analysis Of Cislunar Disposal Options For Select L1 And L2 Orbit Families, Rene Velazquez
Theses and Dissertations
The purpose of this research is to characterize the disposal options available for the planar and out of plane orbit families near the Moon. These options are meant to provide the impending Space Race around the cislunar regime a method to mitigate debris in the future. The disposal options are built upon a Sphere of Influence (SOI) reachability concept from a Circular Restricted Three-Body Problem (CR3BP). The SOI reachability will be based on the maneuver applied on a closed orbit in the velocity direction of the rotating frame. The post-maneuver trajectories will be propagated for 180 days and transformed into …
Statistical Reliability Estimation Of Space Launch Vehicles,
2024
Air Force Institute of Technology
Statistical Reliability Estimation Of Space Launch Vehicles, Brooke N. Wagenblast
Theses and Dissertations
Space launch vehicle reliability is imperative to understand since launch vehicles are crucial in getting payloads into space for a hopefully successful mission. This thesis examines the reliability of commercial, civil, and military space launch vehicles through trend analysis and a variety of statistical methods. Data sets obtained from the Seradata database are analyzed for trends by looking at data subsets including launch date, launch country, final mission orbit, section (commercial, civil or military), launch vehicle family and failed subsystem. First-level Bayesian analysis and mean success rates are performed, primarily split up by launch vehicle family and total launches, and …
Preliminary Architecture Assessment Of Lunar Surface Sensors For Cislunar Ssa,
2024
Air Force Institute of Technology
Preliminary Architecture Assessment Of Lunar Surface Sensors For Cislunar Ssa, Clint J. Spesard
Theses and Dissertations
The exploration of the lunar and cislunar realm is becoming increasingly active as several entities, private and public, foreign and domestic, set their sights beyond traditional Earth-centered space operations. Along with this renewed activity is a growing need for comprehensive Space Situational Awareness (SSA) and Space Traffic Management (STM) in the inherently chaotic cislunar system. This thesis seeks to embolden the study of cislunar SSA by considering the lunar-surface as a platform from which to conduct optical SSA. In this thesis, a lunar-based SSA system is heuristically optimized via a genetic algorithm through three separate implementations. All surface locations considered …
Investigation Of The Effect Of Internal Reynolds Number And Advective Capacity Ratio On Gas Turbine Film Cooling Parameters,
2024
Air Force Institute of Technology
Investigation Of The Effect Of Internal Reynolds Number And Advective Capacity Ratio On Gas Turbine Film Cooling Parameters, John P. Di Lella
Theses and Dissertations
The desire for more powerful engines drives higher turbine inlet temperatures and a greater need to cool them. Experimentalists attempt to match cooling effectiveness between two conditions by matching several non-dimensional parameters, one of which is the coolant warming factor. The first investigation of this study examines the effect of the internal Reynolds number and the advective capacity ratio on the coolant warming factor by making use of a computational model and four different gases. It indicates the non-negligible and opposing effects of external convection and solid conduction on the coolant warming factor at matched internal Reynolds number and advective …
Evasion Strategies For Space Engagements With Unknown Pursuer Objectives,
2024
Air Force Institute of Technology
Evasion Strategies For Space Engagements With Unknown Pursuer Objectives, Stephanie L. Halsey
Theses and Dissertations
Realistic simulations provide a tool for operators to understand space tactics and also serve to inform decisions on the requirements of current spacecraft technologies. This research uses simulation to gain a better understanding of one-on-one orbital conflicts through orbital differential games and linear quadratic games. The results of this research find that a simple strategy for an evading spacecraft to successfully evade a more-capable pursuing satellite for a variety of potential goals is to thrust perpendicular to the direction of the pursuer. Specific estimation requirements to accurately determine the objective of the pursuer and successfully evade in a realistic scenario …
Random Forests For Detecting Weak Signals And Extracting Physical Information: A Case Study Of Magnetic Navigation,
2024
Autonomy and Navigation Technology Center, Air Force Institute of Technology
Random Forests For Detecting Weak Signals And Extracting Physical Information: A Case Study Of Magnetic Navigation, Mohammadamin Moradi, Zheng-Meng Zhai, Aaron Nielsen, Ying-Cheng Lai, Aaron P. Nielsen
Faculty Publications
It has been recently demonstrated that two machine-learning architectures, reservoir computing and time-delayed feed-forward neural networks, can be exploited for detecting the Earth’s anomaly magnetic field immersed in overwhelming complex signals for magnetic navigation in a GPS-denied environment. The accuracy of the detected anomaly field corresponds to a positioning accuracy in the range of 10–40 m. To increase the accuracy and reduce the uncertainty of weak signal detection as well as to directly obtain the position information, we exploit the machine-learning model of random forests that combines the output of multiple decision trees to give optimal values of the physical …
Steminism: Analyzing Factors That Improve Retention Of Women In Stem,
2024
University of Missouri-St. Louis
Steminism: Analyzing Factors That Improve Retention Of Women In Stem, Kira Carter, Jane Kelley, Jason Vasser-Elong, Rc Patterson
Dissertations
Our co-authored research ‘Steminism: Analyzing Factors That Improve Retention for Women as STEM Majors’ analyzed factors that contributed to the retention of women in science, technology, engineering, and mathematics (STEM) programs at Missouri University of Science & Technology (Missouri S&T). Women make up half of the US population, and while careers in (STEM) are an integral part of the US economy, women are underrepresented in these career fields. The purpose of our dissertation is to address the underrepresentation of women in STEM majors. Our methodology included homogeneous sampling to collect qualitative data. More specifically, we consulted with academic advisors and …
Data And Intelligent Driven Space Science Experimental Research: New Exploration Under Ai4s Paradigm,
2024
Technology and Engineering Center for Space Utilization, Chinese Academy of Sciences, Beijing 100094, China; Key Laboratory of Space Utilization, Chinese Academy of Sciences, Beijing 100094, China; School of Aeronautics and Astronautics, University of Chinese Academy of Sciences, Beijing 100049, China
Data And Intelligent Driven Space Science Experimental Research: New Exploration Under Ai4s Paradigm, Shengyang Li, Kang Liu, Yunfei Liu, Chufan Lai
Bulletin of Chinese Academy of Sciences (Chinese Version)
As artificial intelligence (AI) technology continues to advance, it is revolutionizing various scientific fields, giving rise to a new research paradigm known as AI for Science (AI4S). This study highlights the unique multidisciplinary advantages of AI in space science experiments conducted under microgravity conditions. It provides a comprehensive analysis of AI-driven approaches to multimodal space science experiment data pattern mining, domain knowledge extraction, interdisciplinary knowledge integration, and cognitive intelligence. The study reveals AI’s substantial potential to enhance intelligent scientific research, cognition, and discovery within the realm of space science experiments. The findings suggest that data-driven space science research, as a …
