Aerospace Engineering Commons^™

Experimental And Computational Bearing Strength Of Fiber Metal Laminate With And Without Film Adhesive, Christopher L. Bellanova Jr.

Theses and Dissertations

This research characterized the performance of a fiber metal laminate composed of carbon fiber and stainless steel without film adhesive and compared it to a similar, previously tested, fiber metal laminate including film adhesive. Removal of the adhesive layers reduced the localized thickness, simplified manufacturing, and allowed for a 20% increase in foil thickness. Quasi-static testing was conducted in double shear, single shear protruding, and single shear countersunk configurations. The results were compared to adhesive hybrid and control samples. To study the affects of bolt tension, samples at low torque in double shear were also tested. Progressive failure samples revealed …

Estimation Of Optimal Flight Trajectory In A Total Power Loss Scenario Using Proximal Policy Optimization, Eidahn Eliash

Theses and Dissertations

Recent research has been conducted in using deep reinforcement learning algorithms to generate closed form optimal control laws for helicopters in power loss scenarios. The control laws could allow for design of various cockpit visual pilot aids if proven successful. Such pilot aids are predicted to reduce pilot workload during execution of an emergency powerless landing, and to overall increase the probability of landing safely in such an event. The proposed topic discusses the use of the PPO algorithm in order to find an optimal control policy for a helicopter in a total power loss emergency landing scenario. The task …

Suitability Of Earth-Moon Triangular Lagrange Point Orbits For Space Situational Awareness, Eric P. Burkhart

Theses and Dissertations

The second space race is looming on the horizon, and the Moon is again at center stage. All major space fairing nations have plans for future Lunar exploration, but this time with plans to stay. NASA’s Artemis program plans to put humans back on the Moon in 2025 and establish a Lunar base on the South pole in the 2030s. Meanwhile, China has landed a rover on the far side of the moon with a communications relay satellite in a halo orbit around the L2 Lagrange point, and partnered with Russia to build a Lunar research station on the Lunar …

Gaseous Fuel Combustion In A Small Turbojet, Katherine A. Ashton

Theses and Dissertations

This project set out to test the suitability of natural gas as an aviation fuel by comparing how a small turbojet performed when run on traditional jet fuel versus methane. A JetCat P400, originally designed for jet fuel, was modified to run on methane. The modifications made did not succeed at getting the engine to run at normal operating speed on methane, but did get the engine to run at normal operating speeds using ethylene and ethane. It was determined a fuel and air mixing problem was hindering the engine performance when run on methane Future studies improving the fuel …

Overall Effectiveness Superposition Theory For A Film Cooled Leading Edge, Bailey W. Hopkins

Theses and Dissertations

Film cooling experimentation traditionally reports on the cooling performance of specialty-crafted cooling holes at various angles and array patterns. This is repeated across a variety of model geometries in an effort to provide as much information to the turbine blade designer. While this extensive database of cooling performance is helpful, its true value is found in the designer’s ability to effectively superpose the results on top of each other. One technique for predicting the performance of multiple coolant sources is film cooling superposition theory. This analytical model was employed classically by characterizing the adiabatic effectiveness across a model’s surface; however, …

Performance Analysis And Recommended Improvements Of A Cubesat Resistojet, Alexander M. Petrocelli

Theses and Dissertations

A small resistojet design was evaluated for its current performance and assessed for design and operational improvements. This resistojet is designed to operate on AFIT CubeSats with the intent of providing 100-200 mN of thrust at a specific impulse between 66-104 seconds. Using previously collected data and studies conducted on the design, analysis was performed to determine the current performance of this first-generation design. This provided a starting point for performance analysis over a variety of operational temperatures and pressures. This process was conducted for various heat exchanger path lengths of both the current design and two adapted path geometries. …

Investigation Of Hypersonic Near-Wake Relaminarization Over A 7 Degree Half-Angle Cone, Jesse L. Roberts

Theses and Dissertations

To investigate the potential for relaminarization in the near-wake of a 7-degree half-angle cone, a series of hypersonic wake experiments were conducted in the Air Force Research Laboratory Mach 6.1 Ludwieg tube. Relaminarization is a spatial phenomenon that occurs when a turbulent flow reverts to a laminar-like state at a downstream location, where turbulent fluctuations negligibly contribute to average flow properties. Although relaminarization has been documented in subsonic and supersonic flows, the current body of knowledge related to the occurrence of, and mechanisms that drive, relaminarization at hypersonic speeds is sparse. Measurements were obtained across a range of freestream unit …

Shock Induced Trailing Edge Separation Effect On F-16 Limit-Cycle Oscillation, Eric D. Stubblefield

Theses and Dissertations

No abstract provided.

Mechanical Properties And Performance Of A Novel Nano-Engineered Unitized Composite With Quasi-Isotropic Layup, Brian Matthew Pudlo

Theses and Dissertations

Carbon nanotubes (CNTs) exhibit outstanding mechanical, electrical, and thermal properties, but are a challenge to effectively implement into macroscopic composites for aerospace applications. This research investigates the mechanical properties and performance of a newly developed hybrid NanoStitch composite, alongside a control polymer matrix composite, at room temperature. Both composite material systems investigated in this work have quasi-isotropic layup. Monotonic tension-tofailure, tension-tension fatigue, and creep tests were performed to characterize the performance of the composites under cyclic and sustained loading. Experimental results obtained for the quasi-isotropic NanoStitch composite were compared to those obtained for the quasi-isotropic control composite. The properties and …

Debris Survivability Study For Mega-Constellation Architectures, Joseph C. Canoy

Theses and Dissertations

The analysis for the overall theoretical debris survivabilty of mega-constellation architectures, with an emphasis on space-based ballistic missile defense constellation (SB-BMD), is explored via three extensive different Monte Carlo simulations: preliminary analysis of low Earth Orbit (LEO) mega-constellation survivabilty following a fragmentation event within the constellation, analysis of LEO mega-constellation survivability with a fragmentation event occurring on a satellite performing a maneuver to insert itself within the constellation, and the analysis of LEO mega-constellation survivabilty after a fragmentation event resulting from the destruction of a missile. The LEO mega-constellations represent the SB-BMD constellation. The first two analysis sections will include …

Direct Collocation Methods For Comparison Of Aerothermodynamic Models Effect On Hypersonic Trajectory Optimization By The Process Of Continuation, Noor K. Khan

Theses and Dissertations

An algorithm was created to optimize trajectories of hypersonic glide vehicles with selected cost functions by applying the process of continuation to direct orthogonal collocation methods. The trajectory was optimized to maximize the range of launch position given a fixed terminal location. The hypersonic glide vehicle system dynamics were modeled with three-dimensional, three degree of freedom equations of motion assuming no thrust and a non-rotating Earth with the control as bank angle. Three aerothermodynamic models were compared when input as path constraints to calculate the stagnation point heating rate at the nose as well as integrated for heat load. Use …

Characterizing Jet Interaction Effects On A Cone In Mach 3.9 Flow, Titus J. Lee

Theses and Dissertations

Although jet interaction in the context of attitude control for aircraft and air weapons have been investigated for a variety of conditions and geometries, the knowledge base for their use with hypersonic vehicles is far more limited. The objective of the present investigation is to characterize the jet interaction effects in a Mach 3.9 freestream in the AFIT Small Supersonic Wind Tunnel using schlieren flow visualization and a 6-degree of freedom balance. A 7° aluminum cone was attached to the balance while air was injected through a stainless-steel tube, which was separately supported without any contact with the cone body …

Optimal Gyroid Infill For Space Launch, Jose R. Lopez Cordell

Theses and Dissertations

This research characterizes the optimal gyroid infill design for the 1st frequency response of composite sandwich panels. Structural performance may be improved by designing the gyroid infill within the sandwich panel to have a 1st mode resonance frequency above typical launch vehicle vibrations. Ensuring a component generates a natural frequency response above a designed threshold is mandatory for space launch systems to prevent damage. The gyroid, a Triply Periodic Minimal Surface (TPMS), has the potential to provide close to isotropic stiffness in the principal axes with a minimal amount of material, making it an attractive choice for this application. This …

Detonation Confinement In A Second-Generation Radial Rotating Engine, John T. Ursino

Theses and Dissertations

In recent years, Rotating Detonation Engines (RDEs) have been coupled with turbomachinery to harness the benefits of detonative combustion. A novel type of RDE, referred to as the disk or Radial RDE (RRDE), has been developed in pursuit of length and weight savings compared to a traditional annular flow RDE. This design includes a disk-shaped device within which reactants flow from the outer radius, detonate, and exit the inner radius. In this paper several modifications have been made to a previously tested RRDE to address issues that arose with the original design. The combustion chamber diameter has been increased to …

Development Of Novel Turbomachinery Manufacturing Methods, Timothy P. Winkler

Theses and Dissertations

Compact turbine engines are of increasing interest as a means of propulsion for small, lightweight, low cost, unmanned aerial systems. This study looks to leverage advancements in novel manufacturing technology to produce turbomachinery components while simultaneously reducing costs and manufacturing time. To determine the feasibility of drop-in replacements for stock components this study focused on several research areas. This included materials research on both polymer-reinforced and ceramic materials, specimen tensile testing to determine temperature-dependent material properties, finite element analysis of multiple candidate materials, design and fabrication of a spin test rig, and physical spin testing of manufactured components to predict …

Hemodynamic Investigations In Intracranial Aneurysms: A Commentary, Hang Yi, Mark Johnson, Luke Bramlage, Zifeng Yang, Bryan Ludwig

Mechanical and Materials Engineering Faculty Publications

Intracranial aneurysms (IAs) are abnormal bulges in a blood vessel in the brain that have a potential to rupture and even causing a stroke, which can lead to lasting brain damage, long-term disability, or even loss of life. It has been widely acknowledged that hemodynamic factors, e.g., instantaneous wall shear stress, time-averaged wall shear stress, wall shear stress gradient, gradient oscillatory number, oscillatory shear index, pulsatile blood flow waveform (flow rate magnitude and shape, physical flow period), relative residence time/turnover time, blood pressure, and vortex (i.e., size, location, and numbers), have a close relationship with the pathobiology (i.e., initiation, growth, …

Flight Testing Gls Approaches Enabled By Wide Area Corrections In Kerkyra, Greece, Thomas Dautermann, Thomas Ludwig

Journal of Aviation Technology and Engineering

Many airports with a high value to commercial air traffic have spatial or budgetary constraints which prevent the installation of a precision approach system. We previously designed a low-cost precision approach system which combines the advantages of both ground-based and satellite-based augmentation systems by using a converter between them in order to allow GAST-A approach types. We installed, operated, and flight-tested such a system at Kerkyra Airport using an A320 aircraft. During these, we recorded data from a commercial multimode receiver as well as GPS raw data in order to prove the feasibility of the system. Data were analyzed using …

Evaluating System Usability, Workload Suitability, And User Experience Of Game-Based Virtual Reality In Spaceflight Education And Training, Lana Laskey, Joseph R. Keebler

Journal of Aviation/Aerospace Education & Research

Game-based instruction and immersive virtual reality are enhanced pedagogical methods beneficial in training environments involving complex disciplines, ranging from medical applications to construction engineering technology. This study investigated the use of game-based virtual reality (GBVR) when applied to the complex field of spaceflight education and training. As modern society places increasing demand on space-based amenities, the need for proficient satellite operators will also increase, requiring more accessible and advanced training options. Satellite ground control training scenarios, immersed in the GBVR environment, were developed and deployed to university student participants. Multiple validated scales were employed to measure the GBVR system regarding …

Simulation Of Natural Tornado Genesis And Evolution From An Initial Instability Profile, Kakkattukuzhy M. Issac

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A likely mechanism for the little-understood tornado genesis is proposed and its numerical implementation is presented. The Burgers-Rott vortex with its axis in the vertical direction is introduced as an instability mechanism, and the flow field then evolves under the influence of the atmospheric pressure, temperature and density variations with altitude. Buoyancy effects are implemented using the Boussinesq model. Results are presented and discussed for a set of conditions including mesh type and size, different turbulence models, and a few different boundary conditions. Post-processed results of the transient simulations including animations contain a wealth of information to help analyze tornado …

On The Development And Evaluation Of A Framework For Brain-Computer Interface And Vibrotactile Feedback For Human-Robot-Interaction In Virtual Spaces And Robotic Hardware, Sudip Hazra, Shane Whitaker, Panos S. Shiakolas

Mechanical and Aerospace Student Research - Archive

Research in Brain-Computer Interface (BCI) aims to understand human intent with the goal to enhance Human-Robot Interaction (HRI) especially in the field of assistive robotics. The goal of this research is to develop a behavioral sequence based framework to help persons with upper limb disabilities to maintain self-dependence. The framework aims to operate in stages and links multiple functional components to identify human intent and control a robotic arm. The development, operation, and evaluation of the framework and the linked functional components to acquire, process, evaluate, and map BCI signals generated using facial expressions and head movements to predefined actions …

Sensitivity Of Optimal Midcourse Correction Scheduling For Robust Cislunar Trajectory Design, David Geller, David Woffinden, Stefan Bieniawski

Space Dynamics Laboratory Publications

A new approach to optimal trajectory design is the determination of optimal trajectories that are robust to initial trajectory dispersions, navigation errors, maneuver execution errors, and environment modeling errors. This paper investigates the sensitivity of cislunar robust optimal trajectory design to launch date, duration of navigation measurement passes, and navigation measurement frequency. For a given cislunar trajectory from translunar injection (TLI) to lunar orbit insertion (LOI), the optimal locations of midcourse corrections, also known as trajectory correction maneuvers (TCM) are determined by minimizing the final 3-σ ∆v subject to a final 3-σ position dispersion constraint for a …

Urban Air Mobility (Uam) Flight Path: Literature Review And Conceptual Design Of Uam Corridor Virtual Lane System Using “Tracks”, Immanuel Bankole

Student Works

As the Urban Air Mobility (UAM) industry grows and becomes more popular, most of the conversations in the public domain are focused on the (electric Vertical Take-off and Landing) eVTOL aircraft and the physical infrastructure that will support these eVTOL aircraft. However, there is a lack of research on UAM traffic management and flight paths taken by aircraft between locations.

The United States (U.S.) Federal Aviation Administration has proposed the use of corridors to minimize the interaction between UAM operations and traditional air traffic as eVTOL aircraft perform flight activities. The government also acknowledges the need for additional structures (such …

Predicting Industrial Building Energy Consumption With Statistical And Machine-Learning Models Informed By Physical System Parameters, Sean Kapp, Jun-Ki Choi, Taehoon Hong

Mechanical and Aerospace Engineering Faculty Publications

The industrial sector consumes about one-third of global energy, making them a frequent target for energy use reduction. Variation in energy usage is observed with weather conditions, as space conditioning needs to change seasonally, and with production, energy-using equipment is directly tied to production rate. Previous models were based on engineering analyses of equipment and relied on site-specific details. Others consisted of single -variable regressors that did not capture all contributions to energy consumption. New modeling techniques could be applied to rectify these weaknesses. Applying data from 45 different manufacturing plants obtained from industrial energy audits, a supervised machine-learning model …

Synthesizing Ti–Ni Alloy Composite Coating On Ti–6al–4v Surface From Laser Surface Modification, Yitao Chen, Joseph William Newkirk, Frank W. Liou

Materials Science and Engineering Faculty Research & Creative Works

In This Work, a Ni-Alloy Deloro-22 Was Laser-Deposited on a Ti–6Al–4V Bar Substrate with Multiple Sets of Laser Processing Parameters. the Purpose Was to Apply Laser Surface Modification to Synthesize Different Combinations of Ductile TiNi and Hard Ti₂Ni Intermetallic Phases on the Surface of Ti–6Al–4V in Order to Obtain Adjustable Surface Properties. Scanning Electron Microscopy, Energy Dispersion Spectroscopy, and X-Ray Diffraction Were Applied to Reveal the Deposited Surface Microstructure and Phase. the Effect of Processing Parameters on the Resultant Compositions of TiNi and Ti₂Ni Was Discussed. the Hardness of the Deposition Was Evaluated, and Comparisons with …

Glass-Based Biodegradable Pressure Sensor Toward Biomechanical Monitoring With A Controllable Lifetime, Devdatt Chattopadhyay, Jonghyun Park, Chang-Soo Kim

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A New Class of Potentially Implantable Solid-State Sensors is Demonstrated Utilizing Biodegradable Glass as the Main Structural Material. the Device Behavior is Manipulated Via Chemical Decomposition, and Then Physically Disintegrated in a Controlled Manner. It is based on the Capacitive Sensing Mechanism, Comprising an Elastic Insulator between Two Borate-Rich Glass Substrates. This Mesoscale Pressure Sensor is Characterized by a Range of Pressure of Up to 14 MPa in a Phosphate Buffer Solution Environment. the Sensor Exhibits Good Sensitivity and Reversibility Responding to Compressive Pressures and Remains Fully Functional Before a Desired, Sudden Failure Caused by Dissolution. the Operational Lifetime Can …

Selection Of Solidification Pathway In Rapid Solidification Processes, Nima Najafizadeh, Men G. Chu, Yijia Gu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Rapid Solidification Processing of Alloys Enables the Formation of Exotic Nonequilibrium Microstructures. However, the Interrelationship between the Processing Parameters and the Resulting Microstructure is Yet to Be Fully Understood. in Melt Spinning (MS) and Additive Manufacturing (AM) of Rapidly Solidified Alloys, Opposite Microstructure Development Sequences Were Observed. a Fine-To-Coarse Microstructural Transition is Typically Observed in Melt-Spun Ribbons, Whereas Melt Pools in AM Exhibit a Coarse-To-Fine Transition. in This Paper, the Microstructural Evolutions during These Two Processes Are Investigated using Phase-Field Modeling. the Variation of All Key Variables of the Solid-Liquid Interface (Temperature, Composition, and Velocity) throughout the Entire Rapid Solidification …

Heat Transfer In Mini-Channel Heat Exchanger With Smooth And Pin-Fins Surfaces, Mohammed Molham Daadoua

Theses

This research aims to investigate heat transfer of single-phase and two-phase fluids in mini-channel heat exchanger with smooth and pin-fins surfaces. The main goal of the study is to develop a high-performance heat exchanger for thermal management in various processing applications. This research is carried out using computational fluid dynamics (CFD) modeling and experimentations. The proposed method is to use enhanced structured pin-fins surfaces in a mini-channel heat exchanger to improve heat transfer. The pin-fin microchannel heat exchanger is investigated using a CFD method with single-phase fluid (water, air). The experimental investigations are conducted using single-phase and two-phase fluid involving …

Developing Test Methods For Compression After Lightning Strikes, Xiaodong Xu, Scott L. J. Millen, Juhyeong Lee, Gasser Abdelal, Daniel Mitchard, Michael R. Wisnom, Adrian Murphy

Mechanical and Aerospace Engineering Faculty Publications

Research into residual strength after lightning strike is increasing within the literature. However, standard test methods for measuring residual compressive strength after lightning strikes do not exist. For the first time, a systematic experimental study is undertaken to evaluate modifications necessary to standard Compression After Impact (CAI) specimen geometry and test jig design to induce specimen failure at the lightning damage region. Four laboratory generated lightning strike currents with peak amplitudes ranging from 25 to 100 kA have been studied. Test set-up modifications were made considering the scale of the lightning damage and its potential proximity to specimen edges. Specimen …

A Bidirectional Deep Lstm Machine Learning Method For Flight Delay Modelling And Analysis, Desmond B. Bisandu, Irene Moulitsas

National Training Aircraft Symposium (NTAS)

Flight delays can be prevented by providing a reference point from an accurate prediction model because predicting flight delays is a problem with a specific space. Only a few algorithms consider predicted classes' mutual correlation during flight delay classification or prediction modelling tasks. None of these existing methods works for all scenarios. Therefore, the need to investigate the performance of more models in solving the problem of flight delay is vast and rapidly increasing. This paper presents the development and evaluation of LSTM and BiLSTM models by comparing them for a flight delay prediction. The LSTM does the feature extraction …

An Alternate Dimensionless Form Of The Linearized Rigid-Body Aircraft Equations Of Motion With Emphasis On Dynamic Parameters, Douglas F. Hunsaker, Benjamin C. Moulton

Mechanical and Aerospace Engineering Student Publications and Presentations

The equations of motion for an aircraft can be linearized about a reference condition within the assumptions of small disturbances and linear aerodynamics. The resulting system of equations is typically solved to obtain the eigenvalues and eigenvectors that describe the small disturbance motion of the aircraft. Results from such an analysis are often used to predict the rigid-body dynamic modes of the aircraft and associated handling qualities. This process is typically carried out in dimensional form in most text books, or in nondimensional form using dimensionless parameters rooted in aerodynamic theory. Here we apply Buckingham’s Pi theorem to obtain nondimensional …